|
When considering the issue of using nonhuman animals for human food and fiber production, it should be kept in mind that the products made from the animals are not essential for sustaining human life, particularly in so-called developed countries. One can live quite well, perhaps even better, on a completely vegetarian (vegan) diet due to less risk of cancer and other health problems (2, 51, 84, 129, 131). Synthetic materials can substitute adequately for those derived from nonhuman animals. Contrary to popular belief, all essential nutrients are available without an animal-based diet, even the B vitamins (1). In this context, the raising and killing of nonhuman animals is unnecessary.
Its lack of necessity, however, is not the only reason many people are opposed to the use of nonhuman animals for human food and fiber. Opposition also stems from the belief that such use constitutes an abridgment of the rights of the animals involved. This is discussed in more detail in the paper on moral concern in this series.
The conditions under which most nonhuman animals currently are raised for food or fiber fall far short of meeting the animals' needs or interests other than very basic needs such as food, water and, sometimes, shelter (49, 50, 60, 80, 101, 120, 123). In almost all cases, no attention is paid to meeting behavioral or psychological needs. Because of this, the animals merely exist; they do not necessarily experience a state of well-being. I am not referring to obvious abuse and neglect, such as starvation or the withholding of water, which lead to economic loss through poor production or death. I am referring to the quality of life the animals experience and the prevention of the pursuit of their species specific interests (47, 48, 54, 55, 56, 101, 113, 122).
Proponents of current methods, popularly known as 'factory' farming, point out that the system cannot be as bad as its opponents say it is, otherwise there would be loss of productivity. Productivity, however, is not a measure of well-being (52, 54, 80, 85). In most situations, the productivity being measured is based on the unit or group of animals rather than the individual animal. For example, in the typical chicken egg-laying operation, egg production is based on the entire flock and there is no direct information on what each individual chicken is doing (96). When total egg production goes below a certain level, the entire flock is eliminated.
There are numerous simple situations which illustrate that productivity is not a measure of well-being. For example, hens kept under reduced lighting produce fewer eggs. It is difficult to imagine that this also would result in a reduction in well-being especially when you consider that reduced lighting naturally occurs during the winter season.
Cross bred cattle produce more meat, however it is unlikely that they enjoy a higher degree of well-being than others. They may actually have reduced well-being as a result of increased metabolic demands.
Finally, consider two bulls, one ranging freely with several cows and the other closely confined so that his semen can be collected for artificial insemination. The latter bull's productivity with respect to reproduction unquestionably is better than the first bull's. It takes little imagination, however, to conclude that the first bull, by virtue of being unconfined, enjoys a better life with respect to the freedom to pursue whatever interests and behaviors are important to bulls.
When evaluating the effects of a particular housing system on animals, the measure of well-being might be whether the system allows the animal to behave in a normal manner (47, 48, 49, 80, 101, 120). Some people believe that selective breeding has created domestic animals who are genetically very different from their wild ancestors so that they no longer have similar behavioral needs. There is no evidence that this is true. Observation of the animals in question indicates that domestication has had relatively little effect on the animals' behavior when given the opportunity to be expressed (75, 80, 98, 115, 124).
The effects of depriving animals of their behavioral needs can sometimes easily be seen. The present housing systems for chickens and pigs, for example, lead to destructive pecking in chickens and tail biting in pigs, among other problems. Unfortunately, rather than address the underlying cause of these so-called vices, the industry's response is to mutilate the animals to control the problems (3, 19, 96). A major portion of the chicken's beak is burned off and pigs' tails are docked. Surprisingly, the American Veterinary Medical Association is in full support of these practices and considers mutilation a sound management practice (15). In my opinion, this approach is unethical. Moreover, this type of management really is mismanagement in that it fosters this type of aberrant behavior. From a purely management perspective, it would be far better to provide an environment which minimizes this (57). Then those animals still retaining and exhibiting those traits could be culled to prevent any genetic or familial based influences (40, 89, 128).
In some cases, however, the effects of 'factory' farming are not easily measured (50) or the parameters used, such as serum cortisol, are not appropriate (70). Lack of socialization with conspecifics, lack of exercise, or prevention of expression of various behavioral traits, for example, have adverse effects on animals (49, 60, 80). Sometimes these effects cannot be measured or the measurements do not give the total picture (21, 28). Although various parameters can be used to determine objective effects on behavior, physiological factors and the like, the final effect on well-being cannot be determined because this is something which only can be assessed by direct conversation with the individual, something unlikely between nonhuman and human animals.
One must, therefore, have empathy to appreciate the degree of inhumanity of a particular situation. You may have to put yourself in the animals' place and ask yourself if the conditions would be acceptable to you, admittedly a most difficult task given that no human being can truly know what it is like to be another human being let alone an individual of another species. By this I do not mean to consider situations in which inappropriate questions are being asked or inappropriate comparisons are being made. Different species have different requirements or behavioral repertoire. It would be illogical, for example, to consider yourself in the place of a fish with respect to whether you would like to spend your entire life submerged in water, even with appropriate breathing equipment. Rather, I ask that you consider situations which have similar effects on us and other animals. Where evidence to the contrary is lacking, the nonhuman animal should be given the benefit of the doubt. Bear in mind that the animals involved in this situation are not machines or mindless automatons. They are sentient creatures who experience life and death in a manner similar to us. Differences relative to this discussion are largely in degree rather than in kind.
There is considerable hypocrisy in our attitude toward the animals human beings use for food and fiber versus those we deem our family companions. Although a cow's capacity to feel pain and suffer appears to be similar to that of a dog's, our treatment of the cow is substantially different. No rational person would permit the castration of their dog without the benefit of anesthesia nor would anti-cruelty statutes permit this. Likewise, it would be considered extreme cruelty if a hot iron was used to brand a non-anesthetized dog. It is not only legal, however, but also standard operating procedure to castrate and brand cattle without using an anesthetic. This dichotomy is biologically, ethically and legally inconsistent.
I believe most people would agree that we need to provide adequate surroundings and social interaction for 'wild' nonhuman animals confined in zoos. There are data to show that more naturalistic environments or feeding practices lead to healthier animals who may better be able to adjust to their incarceration (27). It seems irrational, at best, for people to object to extending what amounts to the same considerations for nonhuman animals used for food and fiber. I find this very perplexing and saddening. What is the difference between these groups of animals which allows for such dichotomy of concern and treatment?
Agribusiness groups are responsible for disseminating incorrect or misleading information concerning the manner in which nonhuman animals are raised for food and fiber. For example, the American Egg Board approves of children's coloring books which depict chickens in idyllic barnyard conditions with roomy and comfortable coops and family units such as a hen and her chicks. The true manner in which the majority of chickens are raised, however, is in no way similar to this misrepresentation.
The National Dairy Council and Milk Industry Foundation approve of coloring books depicting cattle in idyllic pastures, with calves at their sides. Again, the depiction is starkly at odds with the real situation.
Another issue in modern animal agriculture is the prevalence of drug use in feeds, as growth promoting agents and to prevent infection (8, 22, 88, 102). The use of these agents is recommended to "...combat the effects of stress caused by...crowded conditions" (8). Even the veterinary profession as a whole appears to be supportive of the practice of subtherapeutic use of antibiotics (11), even though it goes against all we were taught about using such agents only in the face of an infection. Moreover, there are data indicating this type of use is associated with increased resistance to antibiotics by various bacteria and constitutes a serious health hazard to people (4, 36, 71, 72, 95, 107, 109, 110).
Although I am sure each person will have seen exceptions, the descriptions in the following paragraphs are of standard husbandry practices at this time. The vast majority of calves raised for 'gourmet' veal are kept in individual stalls in subdued or almost no light except at feeding time, many while chained at the neck (12). They get no exercise, normal grooming is impossible and they cannot even turn around or make normal postural adjustments in the stalls as they get larger. They have nowhere to lie except on the slatted flooring of their crates which often is coated with their own excrement. Even if the crates were cleaned many times a day, this would only reduce, not eliminate, the calves' contact with feces and urine. The feces and urine keep the skin constantly wet and provide an environment which is conducive to infection and inflammation. Ammonia from the urine is a powerful skin irritant. Combined with the lack of bedding, which results in pressure sores from skin rubbing the wooden crate, this sets up a potentially serious skin problem which can cause the calf considerable discomfort and pain.
No opportunity for meaningful social contact with their conspecifics is provided calves raised for veal in this manner. Although the calves normally would begin eating roughage soon after birth, they are fed only a diet which makes them anemic (99, 130) and which contains various drugs which can end up in human food. When taken to slaughter, their legs and musculature are so poorly developed that they walk with difficulty and sometimes sustain fractures.
As a result of all these factors, the calves experience continual stress and other problems (49, 50, 59, 60, 91, 99, 103). It is well known that continuous stress can severely compromise the body's immune system making the individual more prone to disease (26, 67).
There is no need to raise calves under conditions which involve privation and deprivation. The meat from animals who are raised in social groups is just as nourishing for those choosing this type of diet. No studies have shown that there is a discernible difference in the taste or texture compared with that from calves raised in extreme confinement, not that these factors could justify inappropriate housing conditions. Although there will be regional differences, in general, the cost of production in social groups is similar to that in extreme confinement (86, 92).
In the pig industry, the general theme also is one of severe confinement (117, 122). Pregnant sows are confined continuously in individual stalls. Their movement sometimes is restricted further by the use of chains or other type of tether (20, 32). No exercise or nesting is possible even though the urge for such behavior is strong (18, 23, 77, 79). The offspring of the sows sometimes are placed into cages, so-called nurseries. These may be stacked as many as three high. Moderate to severe crowding, to get the most production using the least space, is standard.
These conditions lead to aberrant behavior such as bar-biting and other stereotypic behavior (41, 126) Although there is controversy, there are workers in this area who believe that the stereotypic behavior is an indication of stress and an effort to cope with conditions adverse to well-being (31, 41, 42).
Although proponents of intensive confinement systems point out that the systems are economical and result in less death of piglets or disease in the pigs, there are numerous data showing these types of statements are not necessarily true (7, 24, 34). The capabilities of the individual people involved in the husbandry of the pigs may have a lot to do with improved production in the face of a poor animal environment (63, 64, 106). More naturalistic systems have been successful and profitable (7, 13, 34, 113, 125). Systems involving tethering have been shown to have adverse effects not only on sow welfare, but also on productivity (69) and health (32).
There are numerous problems surrounding the raising of cattle. As mentioned, cattle routinely are castrated and branded without the use of an anesthetic. They also are dehorned at various ages and at various stages of horn development without the benefit of anesthesia. Particularly in the western states, dairy cattle are housed so that they frequently are forced to be in mud, and they often are provided no shade or shelter from weather. Cattle raised for beef often spend the first part of their lives under range conditions, often on public lands which are leased to the ranchers for grazing at $1.97 per animal per month, an extraordinarily cheap rate (35). Moreover, the cattle compete intensely with indigenous free-living animals who often are poisoned, trapped or shot to death because they are viewed as predators or pests (104).
These cattle often spend their last few months in feedlots. These enclosures generally are extremely crowded and dirty, and provide no shade or shelter. During this period, the cattle receive female reproductive hormones, feed medicated with antibiotics, and a concentrated grain diet to 'finish' them. As a result, harmful chemicals may end up in the meat eaten by people (22, 105). The feeding methods lead to many, often painful, gastrointestinal problems in the cattle (54).
Drug residues also are a serious problem in cattle used for milk production and who end up being slaughtered for human food (87). Diseases such as mastitis, a condition which can be extremely painful, can be a complication of the push to develop cows with larger and more productive udders. Other problems can be anticipated with the use of genetically engineered compounds designed to increase productivity (37).
Many well-intentioned people believe that the eating of dairy products cannot be a problem for the animals because you do not have to kill the cow in order to obtain milk. The premise is not true. In order for a cow to lactate, she generally must have been pregnant and have given birth to a calf. Because about 50% of the calves are male and are of no use to the dairy industry, they are killed outright, put into veal production or raised as 'feeder' calves to be killed later. Moreover, the dairy cows are not allowed to lead a normal life and die naturally. They generally are killed before half their natural life span has passed. Eating dairy products, therefore, virtually is no different from eating the flesh of cattle.
Transportation of cattle (38, 65), and other 'farm' animals (58, 65, 90, 116, 121, 127), also creates tremendous problems in terms of animal welfare as well as economics. Losses due to injury and death are estimated to be about $1 billion annually. There are essentially no humane standards or laws applicable to the highway transportation of these animals which accounts for 95% of the animals shipped.
Rabbits traditionally have been overlooked as a major source of food and fiber and thus have not been subjected to the type of privation other animals used for food have endured. Now, however, there is a big push to 'factory' farm rabbits in cages. The does will be kept continually pregnant to produce as many offspring as possible. It is my understanding that there is a push to have cages 4 feet by 20 feet which will each hold 160 rabbits. Each rabbit would have about ½ square foot of floor space.
Life for a newly hatched chick begins at the sorting station. Here, unwanted chicks, generally males because they produce no eggs (if egg layers are being hatched), or deformed ones, often are thrown into plastic bags as if they were inanimate objects (78). Those on the bottom are suffocated or crushed to death by those on top. When the bag is full, it is sealed and discarded, containing chicks who still are alive. Drowning also is used by some companies, even though it does not lead to rapid death (78). Some places have machines which crush the chicks to death, however a chick may first suffer a crushed wing, face or leg before finally being killed.
Chicks 'lucky' enough to get past the sorting station alive end up as 'broilers' or egg producers. So-called broilers are kept under extremely crowded conditions. Because the birds are overcrowded, stress levels and mortality are high (93). The overcrowding prevents the birds from establishing a pecking order and prevents subordinate birds the opportunity to escape from dominant birds. This leads to destructive pecking and cannibalism. One means by which the industry has tried to minimize this is by inserting red contact lenses to alter the wavelength of light impinging on the retina in an effort to create a more subdued environment. In the process, the birds suffered considerable damage to their corneas (68). In a group of individuals I examined, I found the damage to be so severe that there was corneal rupture with loss of an eye.
The standard way to deal with aggression caused by the overcrowding, however, is to cut off a major portion of the chickens' beaks while they are chicks. This procedure, known as debeaking or beak trimming, is claimed to be non-painful or only a "mild stress" by industry representatives or supporters (19). The beak, however, is a complex sensory organ which contains an extensive nerve supply including numerous mechanoreceptors, thermoreceptors and nociceptors (62). Partial beak amputation results in loss of weight, reduced growth, delay in sexual maturity, reduction in egg production rates and possibly a reduction in egg size (39, 96). A small percentage of the chicks die directly as a result of the procedure due to its distressful nature. Painful neuromas may occur which result in chronic pain and depression which may last for many weeks to over a year (30, 62), and the mutilated beak may be subject to the phenomenon of phantom pain (62). Moreover, the tongue sometimes is cut at the same time, leading to inability to eat and starvation. The procedure, therefore, is painful and, under the best of conditions, results in birds who have a difficult time feeding and preening compared with normal birds (135). By allowing a more natural housing system with reduced densities of birds, and by genetic selection (40), one could eliminate the need for this type of mutilation.
Chickens, as well as turkeys, are subjected to other types of mutilation such as toe amputation, dubbing, de-snooding and wing clipping, all without anesthesia (19). Research has shown that not only is the initial procedure painful, negative consequences continue for some time (61). The response of birds such as chickens to noxious stimuli is similar to that seen in mammals (134).
Imagine a piece of cardboard with dimensions of about 12 inches by 18 inches. This represents the floor space of an average wire cage used for housing egg-producing hens (96). Four or five hens spend their entire foreshortened lives within the confines of such a cage. In a typical 'battery' operation there are numerous rows of cages, with as many as four tiers. The feces from hens above fall upon those below.
Because of the crowding, not all the hens can eat at the same time and movement by one necessitates a major disturbance to all in a cage. Because the hens cannot exercise, there is a high prevalence of broken bones due to osteoporosis and a syndrome known as cage-layer fatigue (9, 46, 76, 81, 82). Although modification of the diet may have some effect on these conditions, simply allowing exercise usually will eliminate them (108). The constant contact with bare wire results in considerable damage to the chickens' feet, which in itself is painful. The crowding in these cages, as with the 'broilers,' results in destructive pecking, so the birds are 'debeaked.' There is a high mortality rate in the battery cage system. I have been told this may be as much as one per cent per week.
There is little doubt that the situation in battery cages leads to serious animal welfare and well-being problems (25, 29, 44, 45, 46, 75, 94, 114, 119). Yet, these deplorable conditions are the 'standards' under which essentially all eggs in this country are produced.
Chickens normally go through periodic molts during which they replace their feathers. During molt, the chickens do not produce eggs. If they were allowed to molt naturally, it is alleged that this would be problematical for the producer because it would be erratic. Therefore, after about a year of production, the hens are forced to molt. This is done by withholding water for up to three days and food for up to ten days (96, 132). This leads to severe physiologic shock resulting in rapid and simultaneous loss of feathers. It also increases the shedding of the Salmonella enteritidis bacterium (73, 74, 83). Generally, after a second period of laying, the birds are roughly pulled from their cages and taken to slaughter. There are no laws governing how these birds are handled or transported nor how they are slaughtered.b Therefore, they are overcrowded in crates, exposed to adverse weather and finally slaughtered, often while conscious to some degree (66, 133).
The things I have mentioned are obvious or measurable problems associated with the caged hen. There also is the issue of extreme privation. Hens have very strong behavioral traits which essentially are totally prohibited from being expressed under the standard conditions I mentioned. Wing flapping and stretching, flying, scratching, dust bathing, perching, meaningful socialization, preening and the use of a nest for laying are virtually impossible under these conditions. Most of these behaviors are considered important with respect to the well-being of the hens (94, 118).
There have been many observations indicating that the hens, as well as other so-called food animals, would prefer a different system of housing. It has been shown that hens would choose unconfined systems over cages (44, 46, 75). Prior experience was a modifying factor in that hens raised all their lives in cages initially tended to choose cages over loose housing. After a short period, however, even those hens chose unconfined systems over the cages.
My own experience also indicates that hens will seek a system different from cages. I conducted a modest experiment in which I removed about 20 hens from a research lab, with the investigator's permission. These hens had been raised under the conditions I mentioned previously and had never seen perches, soil or other natural things. By the time I had unloaded them onto the land which was to be their new home, every hen was dust-bathing, something none had done before. That evening, every hen was roosting in trees or on perches, again, something none had seen or done before. It is clear that these behavioral traits have not been bred out of chickens and, more importantly, they easily were elicited indicating they remain very strong urges.
Why be concerned about so-called food animals who are being raised simply to be killed? The fact that an animal is being raised just to be killed has no relevance. We all are going to die sometime, too. That is not, however, the basis on which we would like to be treated. The key issue is the quality of life. Moreover, we are talking about a tremendous number of lives when we are dealing with 'food' animals. To put the situation into perspective, consider the types and annual toll of nonhuman animals about whom humane societies have traditionally been concerned: 200,000 harp seals, eight million horses, 7-19 million 'excess' cats and dogs, and 22-60 million animals used in laboratories. By contrast, the number of nonhuman animals killed for food and fiber in the United States alone is in excess of nine billion every year.
Do all these animals end up being eaten, and is the available protein efficiently used? The answer clearly is no. Best estimates indicate that a minimum of one-third to one-half of the protein is not consumed due to carcass damage, spoilage and other problems. That means that up to 4.5 billion animals are needlessly killed after experiencing unnecessary privation under our present husbandry methods. This waste is compounded by the fact that we eat far more protein than is necessary to sustain life. Simply improving the efficiency of utilization of this protein source would result in a major reduction in the number of animals used for food. The economic loss to the producer also is substantial (65).
There are other serious concerns about depending upon an animal-based source of food. It is extremely inefficient in terms of conversion of plant protein to animal protein. The conversion ratio is considerably greater than 1:1, perhaps as high as 20:1 in the worst case (10). Because in this country a majority of the plant material fed to the animals is from arable land, land which could be used to produce human food, it makes little sense to continue this.
There are other problems of resource use or waste involving nonhuman animal agriculture. The production of animal products is extremely wasteful of water, topsoil, land and energy (10, 100). For example, most of the U.S. land used for crops is planted with livestock feed and more than half of all water consumed in the U.S. goes to livestock (10). A pound of steak from steers in feedlots costs 2,500 gallons of water, a gallon of gasoline in energy and 35 pounds of eroded topsoil (10).
I often am challenged with the argument that plants may feel pain and suffer, therefore I am being cruel by eating them. This is nonsensical for several reasons. Plants do not appear to have an anatomy which would subserve pain or suffering. Furthermore, plants often reproduce by the very act of being eaten (for example, seed-bearing fruits and vegetables), or can have parts of them eaten without being killed (fruits, nuts and the like) so it appears to be in their interest to be eaten, something which cannot be said for animals. I acknowledge that it appears axiomatic that some living being must die in order for another to live. Even if plants did suffer, however, those who eat nonhuman animals must necessarily be responsible for the death and suffering of more plants by eating the inefficient protein-converting animal.
If one still wants to eat nonhuman animals, there are numerous, economical methods of raising them for food and fiber which do not require the extreme confinement, deprivation and privation of the present industry standard. The trite argument that we must do it in the present fashion in order to get food at a reasonable price simply is not true. It has been shown that what you gain in labor cost savings from 'factory' farming is offset by the cost of equipment and other factors (43). Practical application of less intense housing systems has shown that these can be just as productive, safe for the animals and financially sound as 'factory' farming (5, 6, 14, 16, 17, 33, 34, 53, 63, 86, 92, 97, 111, 112, 125). In the case of pigs, a pasture system has been shown by workers at the University of Tennessee to be significantly more efficient and financially cheaper than a confinement system (7). There were less post-weaning losses and disease as well as better consistency in sow and pig performance.
Whether you eat nonhuman animals or wear products made from them is a personal choice. Bear in mind, however, that the animals you eat have lives and interests of their own. They suffer pain, frustration and boredom in a manner similar to you. They at least have a right to enjoy a reasonable life before being killed at our hands. Certainly, their life should be as close to a natural existence as is feasible. It is not important that they are going to die anyway. Rather, it is the quality of life they experience which matters. We should not be the only ones to enjoy freedom of movement and freedom of expression. Customs, convenience, economics and sheer utility are not ethically valid reasons for preventing these animals from living a decent life.
|
1. Albert, M.J.; Mathan, V.I., Baker, S.J.: Vitamin B12 synthesis by human small intestinal bacteria. Nature 283: 781-782, 1980 (21 February).
"However, the human small intestine also often harbours a considerable microflora...and this is even more extensive in apparently healthy southern Indian subjects...We now show that at least two groups of organisms in the small bowel, Pseudomonas and Klebsiella sp., may synthesise significant amounts of the vitamin."
2. Anderson, James W.; Johnstone, Bryan M. and Cook-Newell, Margaret E.: Meta-analysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine 333 (5): 276-282, 1995 (3 August).
"We found that the consumption of soy protein rather than animal protein significantly decreased serum concentrations of total cholesterol, [low-density lipoprotein] cholesterol, and triglycerides."
3. Anonymous: Animal agriculture: Myths & facts. Undated.
4. Anonymous: The Effects on Human Health of Subtherapeutic Use of Antimicrobials in Animal Feeds. Washington:National Academy of Sciences, 1980.
5. Anonymous: Wild pigs point the way. AWI Quarterly 31: 7, 1982.
6. Anonymous: Rooting for pigs in Mexico. AWI Quarterly 34: 6-7, 1985a.
7. Anonymous: News item on pig research done at the University of Tennessee. AWI Quarterly 34: 7, 1985b.
8. Anonymous: BMD antibiotic: What's in it for your hogs? Faster growth. Animal Health & Nutrition 40: 16-17, 1985c.
9. Anonymous: Osteomalacia (cage layer fatigue). C.V.D.L.S. Lab Notes 1: 5, 1988a.
10. Anonymous: What it takes to get a steak. Science News 133: 153, 1988b.
11. Anonymous: Feed antibiotic rotation improves performance in hogs, reduces feed costs. Animal Health News and Feature Tips 5: 2, 1989a.
12. Anonymous: Modern veal production: An industry perspective. Booklet by Veal Committee of the Beef Industry Council, National Live Stock and Meat Board, 57 pp., 1989b.
13. Anonymous: The Petersons talk about Pastureland pigs. AWI Quarterly 38: 10-12, 1989/90.
14. Anonymous: Virginia farmer raises free ranging chickens. AWI Quarterly 39: 11, 1990.
15. Anonymous: The veterinarian's role in animal welfare. 16 page pamphlet by American Veterinary Medical Association; 1997 (January).
16. Anonymous: Pigs on dirt. Large Animal Veterinarian 48 (2): 5-7, 1993 (February).
17. Appleby, M.C., Hogarth, G.S., Anderson, Jessie A., Hughes, B.O. and Whittemore, C.T.: Performance of a deep litter system for egg production. British Poultry Science 29: 735-751, 1988.
18. Arey, D.S.; Petchey, A.M. and Fowler, V.R.: The preparturient behaviour of sows in enriched pens and the effect of pre-formed nests. Applied Animal Behaviour Science 31 (1-2): 61-68, 1991 (July).
"Nest building is highly motivated behaviour in sows and the performance of the activities themselves appears to have a significant role in reducing the motivation. Nesting material appears to be a key factor both in the regulation and performance of the behaviour."
19. Baker, F.H., Beck, A.M., Binkerd, E.F., Blosser, T.H., Brown, K.I., Corah, L.R., Curtis, S.E., Fox, M.W., Hahn, G.L., Johnson, D.E., Kearl, W.G., Kinsman, D.M., Lechtenberg, V.L., Marten, G.C., Montgomery, M.J., Ohlendorf, G.W., Preston, R.L., Rice, R.W., Ringer, R.K., Robinson, F.R., Schneider, N.R., Ullrey, D.E., Willham, R.L. and Young, J.: Scientific aspects of the welfare of food animals. Council for Agricultural Science and Technology: 54 pp., 1981.
20. Barnett, J.L., Winfield, C.G., Cronin, G.M., Hemsworth, P.H. and Dewar, A.M.: The effect of individual and group housing on behavioural and physiological responses related to the welfare of pregnant pigs. Applied Animal Behaviour Science 14: 149-161, 1985.
21. Barnett, J.L. and Hemsworth, P.H.: The validity of physiological and behavioural measures of animal welfare. Applied Animal Behaviour Science 25: 177-187, 1990.
22. Bevill, R.F.: Factors influencing the occurrence of drug residues in animal tissues after the use of antimicrobial agents in animal feeds. Journal of the American Veterinary Medical Association 185: 1124-1126, 1984.
23. Blackshaw, J.K.: Prostaglandin F2 induced nest building behavior in the non-pregnant sow, and some welfare considerations. International Journal for the Study of Animal Problems 4: 299-304, 1983.
24. Blackshaw, J.K. and Hagelso, A.M.: Getting-up and lying-down behaviours of loose-housed sows and social contacts between sows and piglets during day 1 and day 8 after parturition. Applied Animal Behaviour Science 25: 61-70, 1990.
25. Blokhuis, H.J.: Feather-pecking in poultry: Its relation with ground-pecking. Applied Animal Behaviour Science 16: 63-67, 1986.
26. Bogden, A.E.: The effects of environmental stress on immunological responses. In Environmental Variables in Animal Experimentation, Magalhaes, H., Lewisburg:Bucknell University Press, pp. 75-95, 1974.
27. Bond, J.C. and Lindburg, D.G.: Carcass feeding of captive cheetahs (Acinonyx jubatus): the effects of a naturalistic feeding program on oral health and psychological well-being. Applied Animal Behaviour Science 26: 373-382, 1990.
28. Bradshaw, R.H.: Letter to the editor: The science of animal welfare and the subjective experience of animals. Applied Animal Behaviour Science 26: 191-193, 1990.
29. Brantas, G.C.: The pre-laying behaviour of laying hens in cages with and without laying nests. In The Laying Hen and Its Environment. Current Topics in Veterinary Medicine and Animal Science, Volume 8, Moss, R., The Hague:Martinus Nijhoff Publishers, pp. 227-237, 1980.
30. Breward, J. and Gentle, M.J.: Neuroma formation and abnormal afferent nerve discharges after partial beak amputation (beak trimming) in poultry. Experientia 41: 1132-1134, 1985.
31. Broom, D.M.: Sow welfare indicators. Veterinary Record 123: 235, 1988.
32. Cariolet, R. and Dantzer, R.: Motor activity of pregnant tethered sows. Annales de Recherches Veterinaires 15: 257-261, 1984.
33. Carnell, Paul: Alternatives to Factory Farming. London:Earth Resources Research Ltd, 1983.
34. Clanton, C.A.: Raising 10,000 hogs on a patch of dirt and a ton of common sense. National Hog Farmer 31: 14-17, 1986.
35. Clifton, M.: No more pork barrel for the meat industry? The Animals' Agenda 11: 38-39, 1991.
36. Cohen, M.L. and Tauxe, R.V.: Drug-resistant Salmonella in the United States: An epidemiologic perspective. Science 234: 964-969, 1986.
37. Cole, J.A. and Hansen, P.J.: Effects of administration of recombinant bovine somatotropin on the responses of lactating and nonlactating cows to heat stress. Journal of the American Veterinary Medical Association 203 (1): 113-117, 1993 (1 July).
"For lactating and nonlactating cows, those treated with BST had higher rectal temperatures and rate of open-mouth panting than cows treated with [the control] solution. Administration of BST can increase the severity of responses of cows to heat stress without changing milk yield."
38. Cole, N.A., Camp, T.H., Rowe, L.D., Stevens, D.G. and Hutcheson, D.P.: Effect of transport on feeder calves. American Journal of Veterinary Research 49: 178-183, 1988.
39. Christmas, R.B.: Research note: The performance of spring- and summer-reared broilers as affected by precision beak trimming at seven days of age. Poultry Science 72 (12): 2358-2360, 1993 (December).
"Performance of spring-reared broilers was comparable regardless of beak trimming procedure, except that [precision beak-trimmed] broilers experienced slightly higher mortality after PBT. ...PBT resulted in significantly reduced final body weights and feed intake."
"The finding of other research that beak trimming of market broilers generally resulted in reduced body weight and feed intake (Andrews, 1977) was also confirmed by the present studies."
40. Craig, J.V. and Lee, H.-Y.: Beak trimming and genetic stock effects on behavior and mortality from cannibalism in white leghorn-type pullets. Applied Animal Behaviour Science 25: 107-123, 1990.
41. Cronin, G.M. and Wiepkema, P.R.: An analysis of stereotyped behaviour in tethered sows. Annales de Recherches Veterinaires 15: 263-270, 1984.
42. Cronin, G.M., Wiepkema, P.R. and van Ree, J.M.: Endorphins implicated in stereotypies of tethered sows. Experientia 42: 198-199, 1986.
43. Curtis, S.E.: Environmental Management in Animal Agriculture. Ames:Iowa State University Press, 1983.
44. Dawkins, M.S.: Animal Suffering: The Science of Animal Welfare. New York:Chapman and Hall, 1980.
45. Dawkins, M.S.: Time budgets in red junglefowl as a baseline for the assessment of welfare in domestic fowl. Applied Animal Behaviour Science 24: 77-80, 1989.
46. Dawkins, M.S. and Nicol, C.: No room for manoeuvre. New Scientist 123: 44-46, 1989.
47. De Koning, R.: An environmental model for sows: Materializing physical and behavioural needs. Annales de Recherches Veterinaires 15: 303-309, 1984.
48. Dellmeier, G.R.: Motivation in relation to the welfare of enclosed livestock. Applied Animal Behaviour Science 22: 129-138, 1989.
49. Dellmeier, G.R., Friend, T.H. and Gbur, E.E.: Comparison of four methods of calf confinement. II. Behavior. Journal of Animal Science 60: 1102-1109, 1985.
50. Dellmeier, G., Friend, T. and Gbur, E.: Effects of changing housing on open-field behavior of calves. Applied Animal Behaviour Science 26: 215-230, 1990.
51. Esselstyn, Caldwell B.: American Association of Endocrine Surgeons. Presidential address: Beyond surgery. Surgery 110 (6): 923-927, 1991 (December).
" Although coronary artery disease remains the leading killer in our society, it is still unknown and will never be heard of by four of the five billion people world wide. It is strictly an illness of Western civilization and those of other cultures who have adopted the affluent Western lifestyle. ... Americans consume 135 pounds of fat per year, one ton for every 15 years, and 4 tons of fats and oils have been consumed by age 60. ... When such a life-threatening disease can be promptly arrested, it is perplexing to note the continued emphasis of mechanical measures to treat the disease.
...it is apparent that cholelithiasis is part of the price of achieving the Western way of life.
Nations that consume greater amounts of dietary fat per person have the highest mortality rates from breast cancer...When persons migrate from a nation of low incidence of breast cancer to a nation of higher frequency, these immigrants will have the same high rate of breast cancer as their new nation by the second and third generation...
...carcinoma of the prostate gland, which closely correlates with the epidemiologic factors of breast cancer in terms of fat consumption...
...association of fat with an increased incidence of carcinoma of the colon. ... Women who consume red meat daily had a 2.5 times risk of colon cancer compared to those who ate red meat less than once a month. No associated increased risk was noted with vegetable fat. ... Possible mechanisms include the observation that diets high in fat increase the excretion of bile acids... which have been noted in persons with higher rates of colon cancer and polyps...Bile acids act as a tumor promoter... ...bile acid modification by intestinal flora is decreased in vegetarians and those who reduce their beef fat intake...
...osteoporosis, a disease of protein excess. ... The women of Bantu who are over 60 years of age do not have osteoporosis. They have a huge calcium drain, having an average of 10 children and nursing each child for 14 months. Their diet includes 440 mg of calcium per day, half of our recommended daily allowance... They are protected because they eat only 50 gm of protein daily. When they move to civilization their protein intake increases and they develop osteoporosis... The Eskimo consumes a diet that is high in protein (250 to 400 gm per day) and a diet high in calcium (2000 mg per day); yet, despite much physical activity, they have one of the highest rates of osteoporosis... Millions of Americans have osteoporosis, accounting for 190,000 hip fractures annually... Fifteen thousand women die each year as a result of hip fractures. Despite such data, osteoporosis is unknown in many countries around the world except in Western civilization, which consumes two to three times more protein than required."
52. Faure, J-M.: Operant determination of the cage and feeder size preferences of the laying hen. Applied Animal Behaviour Science 15: 325-336, 1986.
53. Fölsch, D.W., Dolf, C., Ehrbar, H., Bleuler, T. and Teijgeler, H.: Ethologic and economic examination of aviary housing for commercial laying flocks. International Journal for the Study of Animal Problems 4: 330-335, 1983.
54. Fox, M.W.: Intensive 'factory' farming and the question of animal rights. Animal Regulation Studies 2: 175-190, 1979/1980.
55. Fox, M.W.: Farm Animals: Husbandry, Behavior, and Veterinary Practice. Baltimore:University Park Press, 1984.
56. Fraser, D.: Role of ethology in determining farm animal well-being. S.C.A.W. Newsletter 12: 8-13, 1990.
57. Fraser, David; Phillips, P.A.; Thompson, B.K. and Tennessen, T.: Effect of straw on the behaviour of growing pigs. Applied Animal Behaviour Science 30 (3-4): 307-318, 1991 (May).
"In these studies, where straw was not required to compensate for deficiencies such as low temperatures or hunger, the one major function of straw was to provide a stimulus and outlet for rooting and chewing, with a resulting reduction in such activities directed at pen-mates."
58. Freeman, B.M.: Transportation of poultry. World's Poultry Science Journal 40: 19-30, 1984.
59. Friend, T.H., Dellmeier, G.R. and Gbur, E.E.: Comparison of four methods of calf confinement. I. Physiology. Journal of Animal Science 60: 1095-1101, 1985.
60. Friend, T.H., Dellmeier, G.R. and Gbur, E.E.: Effects of changing housing on physiology of calves. Journal of Dairy Science 70: 1595-1600, 1987.
61. Gentle, M.J. and Hunter, L.H.: Neural consequences of partial toe amputation in chickens. Research in Veterinary Science 45: 374-376, 1988.
62. Gentle, M.J., Waddington, D., Hunter, L.N. and Jones, R.B.: Behavioural evidence for persistent pain following partial beak amputation in chickens. Applied Animal Behaviour Science 27: 149-157, 1990.
63. Gnatzig, B.: Happy hogs grow faster, breed easier. National Hog Farmer 28: 24,26, 1983.
64. Gonyou, H.W., Hemsworth, P.H. and Barnett, J.L.: Effects of frequent interactions with humans on growing pigs. Applied Animal Behaviour Science 16: 269-278, 1986.
65. Grandin, T.: Bruises and carcass damage. International Journal for the Study of Animal Problems 1: 121-137, 1980.
66. Gregory, N.G. and Wotton, S.B.: Effect of electrical stunning on the electroencephalogram in chickens. British Veterinary Journal 143: 175-183, 1987.
67. Gross, W.B. and Siegel, P.B.: Socialization as a factor in resistance to infection, feed efficiency, and response to antigen in chickens. American Journal of Veterinary Research 43: 2010-2012, 1982.
68. Gvaryahu, G.; Snapir, N. and Grossman, E.: Contact lenses for laying hens. Journal of Applied Poultry Research 6: 449-452, 1997.
"...contact lenses appear to be associated with an increase in eye irritations and thus their application is discouraged."
69. Hansen, L.L. and Vestergaard, K.: Tethered versus loose sows: Ethological observations and measures of productivity: II. Production results. Annales de Recherches Veterinaires 15: 185-191, 1984.
70. Herd, R.M.: Serum cortisol and "stress" in cattle. Australian Veterinary Journal 66: 341-342, 1989.
71. Holmberg, S.D., Wells, J.G. and Cohen, M.L.: Animal-to-man transmission of antimicrobial-resistant Salmonella: Investigations of U.S. outbreaks, 1971-1983. Science 225: 833-835, 1984a.
72. Holmberg, S.D., Osterholm, M.T., Senger, K.A. and Cohen, M.L.: Drug-resistant Salmonella from animals fed antimicrobials. New England Journal of Medicine 311: 617-622, 1984b.
73. Holt, Peter S. and Porter, Robert E.: Microbiological and histopathological effects of an induced-molt fasting procedure on a Salmonella enteritidis infection in chickens. Avian Diseases 36 (3): 610-618, 1992 (July-September).
74. Holt, Peter S. and Porter, Robert E.: Effect of induced molting on the recurrence of a previous Salmonella enteritidis infection. Poultry Science 72 (11): 2069-2078, 1993 (November).
75. Hughes, B.O.: The assessment of behavioural needs. In The Laying Hen and Its Environment. Current Topics in Veterinary Medicine and Animal Science, Volume 8, Moss, R. (ed), The Hague:Martinus Nijhoff Publishers, pp. 149-166, 1980.
76. Hughes, B.O. and Appleby, M.C.: Increase in bone strength of spent laying hens housed in modified cages with perches. Veterinary Record 124: 483-484, 1989.
77. Hutson, G.D. and Haskell, M.J.: The behaviour of farrowing sows with free and operant access to an earth floor. Applied Animal Behaviour Science 26: 363-372, 1990.
78. Jaksch, W.: Euthanasia of day-old male chicks in the poultry industry. International Journal for the Study of Animal Problems 2: 203-213, 1981.
79. Jensen, P.: Nest site choice and nest building of free-ranging domestic pigs due to farrow. Applied Animal Behaviour Science 22: 13-21, 1989.
80. Kiley-Worthington, M.: The behavior of confined calves raised for veal: Are these animals distressed? International Journal for the Study of Animal Problems 4: 198-213, 1983.
81. King, D.F.: Effects of cage size on cage layer fatigue. Poultry Science 44: 898-900, 1965.
82. Knowles, T.G. and Broom, D.M.: Limb bone strength and movement in laying hens from different housing systems. Veterinary Record 126: 354-356, 1990.
83. Kogut, M.H.; Genovese, K.J. and Stanker, L.H.: Effect of induced molting on heterophil function in White Leghorn hens. Avian Diseases 43 (3): 538-548, 1999 (July-September).
Feed withdrawal to induce molt alters the number and decreases the efficiency of peripheral blood heterophils. This appears to play a role in the increased susceptibility of molting hens to Salmonella enteritidis infections.
84. Lee, H.P., Gourley, L., Duffy, S.W., Estève, J., Lee, J. and Day, N.E.: Dietary effects on breast-cancer risk in Singapore. Lancet 337: 1197-1200, 1991.
85. Luescher, U.A., Friendship, R.M., Lissemore, K.D. and McKeown, D.B.: Clinical ethology in food animal practice. Applied Animal Behaviour Science 22: 191-214, 1989.
86. MacFadyen, J.T.: A date with Rambling Rose: Excursions into humane husbandry. Harrowsmith: 67-75, 1986.
87. Marteniuk, J.V., Ahl, A.S. and Bartlett, P.C.: Compliance with recommended drug withdrawal requirements for dairy cows sent to market in Michigan. Journal of the American Veterinary Medical Association 193: 404-407, 1988.
88. Mason, J.: America's other drug problem: Down on the factory pharmacy. The Animals' Agenda 10: 47-49, 1990.
89. McBride, G. and Craig, J.V.: Environmental design and its evaluation for intensively housed animals. Applied Animal Behaviour Science 14: 211-224, 1985.
90. Mills, D.S. and Nicol, C.J.: Tonic immobility in spent hens after catching and transport. Veterinary Record 126: 210-212, 1990.
91. Morisse, J.P.; Cotte, J.P.; Huonnic, D. and Martrenchar, A.. Influence of dry feed supplements on different parameters of welfare in veal calves. Animal Welfare 8 (1): 43-52, 1999 (February).
92. Mosner, M.S.: No need to be boxed in: group pens and grain for veal calves. International Journal for the Study of Animal Problems 3: 207-209, 1982.
93. Newberry, R.C. and Hall, J.W.: Use of pen space by broiler chickens: Effects of age and pen size. Applied Animal Behaviour Science 25: 125-136, 1990.
94. Nicol, C.J.: Social influences on the comfort behaviour of laying hens. Applied Animal Behaviour Science 22: 75-81, 1989.
95. Nikolich, M.P.; Hong, G.; Shoemaker, N.B. and Salyers, A.A.: Evidence for natural horizontal transfer of tetQ between bacteria that normally colonize humans and bacteria that normally colonize livestock. Applied and Environmental Microbiology 60 (9): 3255-3260, 1994 (September).
From MEDLINE: We present evidence that natural transfer of a tetracycline resistance gene, tetQ, has occurred between bacterial genera that normally colonize different hosts. A DNA sequence comparative approach was taken to examine the extent of horizontal tetQ dissemination between species of Bacteroides, the predominant genus of the human colonic microflora, and between species of Bacteroides and of the distantly related genus Prevotella, a predominant genus of the microflora of the rumens and intestinal tracts of farm animals. Virtually identical tetQ sequences were found in a number of isolate pairs differing in taxonomy and geographic origin, indicating that extensive natural gene transmission has occurred. Among the exchange events indicated by the evidence was the very recent transfer of an allele of tetQ usually found in Prevotella spp. to a Bacteroides fragilis strain.
96. North, M.O. and Bell, D.D.: Commercial Chicken Production Manual, Fourth Edition. New York:Van Nostrand Reinhold, 1990.
97. Petersen, V., Recén, B. and Vestergaard, K.: Behaviour of sows and piglets during farrowing under free-range conditions. Applied Animal Behaviour Science 26: 169-179, 1990.
98. Price, E.O.: Behavioral aspects of animal domestication. Quarterly Review of Biology 59: 1-32, 1984.
99. Reece, W.O. and Hotchkiss, D.K.: Blood studies and performance among calves reared by different methods. Journal of Dairy Science 70: 1601-1611, 1987.
100. Reid, J.T. and White, O.D.: Energy cost of food production by animals. In New Protein Foods, Vol. 3: Animal Protein Supplies, Part A. Altschul, A.M. and Wilcke, H.L. (eds), Academic Press, Inc., pp. 116-143, 1978.
101. Rollin, B.E.: Animal welfare, animal rights and agriculture. Journal of Animal Science 68: 3456-3461, 1990.
102. Roudaut, B. and Moretain, J.P.: Residues of macrolide antibiotics in eggs following medication of laying hens. British Poultry Science 31: 661-675, 1990.
103. Saeed, A. Mahdi; Bowersock, T.; Runnels, L. and Teclaw, R.F.: The role of pathogenic Escherichia coli in the etiology of veal calf hemorrhagic enteritis. Preventive Veterinary Medicine 17 (1-2): 65-75, 1993 (October).
104. Satchell, M. and Schrof, J.M.: Uncle Sam's war on wildlife. U.S. News & World Report: 36-37, 1990.
105. Schell, Orville: Modern Meat. New York:Random House, 1984.
106. Seabrook, M.F.: The psychological interaction between the stockman and his animals and its influence on performance of pigs and dairy cows. Veterinary Record 115: 84-87, 1984.
107. Shoemaker, N.B.; Wang, G.R. and Salyers, A.A.: Evidence for natural transfer of a tetracycline resistance gene between bacteria from the human colon and bacteria from the bovine rumen. Applied and Environmental Microbiology 58 (4): 1313-1320, 1992 (April).
From MEDLINE: Previously, we demonstrated conjugal transfer of a specially constructed shuttle vector, pRDB5, from the human colonic anaerobe Bacteroides uniformis to the ruminal anaerobe Prevotella (Bacteroides) ruminicola B(1)4. We have now shown that naturally occurring gene transfer elements in Bacteroides species and Prevotella ruminicola can also be transferred between these two genera. A self-transmissible chromosomal element originally found in a clinical isolate of Bacteroides fragilis (Tcr Emr 12256) was transferred from B. uniformis 0061 to P. ruminicola B(1)4 and from P. ruminicola B(1)4 back to B. uniformis or to another human colonic species, Bacteroides thetaiotaomicron. Similarly, a conjugative plasmid (pRRI4) originally found in P. ruminicola 223 was transferred from P. ruminicola B(1)4 to B. uniformis or B. thetaiotaomicron. pRRI4 could be transferred from the colonic Bacteroides species only if the donor strain contained the Tcr Emr 12256 element in its chromosome. These results show that transfer of naturally occurring elements can be demonstrated under laboratory conditions. Evidence that such transfers may actually have occurred in nature came from our finding that the tetracycline resistance (Tcr) gene on the P. ruminicola plasmid pRRI4 hybridized on high-stringency Southern blots with the Tcr gene found on the Bacteroides Tcr elements. The presence of the same gene in such distantly related genera of bacteria is most likely to have occurred as a result of horizontal transfer.
108. Simonsen, H.B.: Ingestive behaviour and wing-flapping in assessing welfare of laying hens. In Indicators Relevant to Farm Animal Welfare, Smidt, D. (ed), Boston:Martinus Nijhoff Publishers, pp. 89-95, 1983.
109. Smith, Kirk E.; Besser, John M.; Hedberg, Craig W.; Leano, Fe T.; Bender, Jeffrey B.; Wicklund, Julie H.; Johnson, Brain P.; Moore, Kristine A.; Osterholm, Michael T.; et al.: Quinolone-resistant Campylobacter jejuni infections in Minnesota, 1992-1998. New England Journal of Medicine 340 (20): 1525-1532, 1999 (20 May).
"...the number of quinolone-resistant infections acquired domestically has also increased, largely because of the acquisition of resistant strains from poultry. The use of fluoroquinolones in poultry, which began in the United States in 1995, has created a reservoir of resistant C. jejuni."
110. Speer, B.S.; Shoemaker, N.B. and Salyers, A.A.: Bacterial resistance to tetracycline: mechanisms, transfer, and clinical significance. Clinical Microbiology Reviews 5 (4): 387-399, 1992 (October).
From MEDLINE: Tetracycline has been a widely used antibiotic because of its low toxicity and broad spectrum of activity. However, its clinical usefulness has been declining because of the appearance of an increasing number of tetracycline-resistant isolates of clinically important bacteria. Two types of resistance mechanisms predominate: tetracycline efflux and ribosomal protection. A third mechanism of resistance, tetracycline modification, has been identified, but its clinical relevance is still unclear. For some tetracycline resistance genes, expression is regulated. In efflux genes found in gram-negative enteric bacteria, regulation is via a repressor that interacts with tetracycline. Gram-positive efflux genes appear to be regulated by an attenuation mechanism. Recently it was reported that at least one of the ribosome protection genes is regulated by attenuation. Tetracycline resistance genes are often found on transmissible elements. Efflux resistance genes are generally found on plasmids, whereas genes involved in ribosome protection have been found on both plasmids and self-transmissible chromosomal elements (conjugative transposons). One class of conjugative transposon, originally found in streptococci, can transfer itself from streptococci to a variety of recipients, including other gram-positive bacteria, gram-negative bacteria, and mycoplasmas. Another class of conjugative transposons has been found in the Bacteroides group. An unusual feature of the Bacteroides elements is that their transfer is enhanced by preexposure to tetracycline. Thus, tetracycline has the double effect of selecting for recipients that acquire a resistance gene and stimulating transfer of the gene.
111. Stevens, C.: A visit to 15,000 contented hens. AWI Quarterly 32: 6-7, 1983.
112. Stevens, C.: Factory Farming: The Experiment that Failed. Washington:The Animal Welfare Institute, 1987.
113. Stolba, A. and Wood-Gush, D.G.M.: The identification of behavioural key features and their incorporation into a housing design for pigs. Annales de Recherches Veterinaires 15: 287-299, 1984.
114. Taylor, Allison A. and Hurnik, J. Frank: The effect of long-term housing in an aviary and battery cages on the physical condition of laying hens: Body weight, feather condition, claw length, foot lesions, and tibia strength. Poultry Science 73 (2): 268-273, 1994 (February).
"Overall, the results suggest that aviary systems can offer some distinct advantages over traditional battery cages with regard to the physical condition of laying hens, given a high level of management."
115. Tennessen, T.: Coping with confinement - Features of the environment that influence animals' ability to adapt. Applied Animal Behaviour Science 22: 139-149, 1989.
116. Thomas, K.W., Kelly, A.P., Beers, P.T. and Brennan, R.G.: Thiamine deficiency in sheep exported live by sea. Australian Veterinary Journal 67: 215-218, 1990.
117. Tubbs, Roderick C.: The growing/finishing swine herd: Nursery management. Veterinary Medicine 90 (3): 304-309, 1995 (March).
"[Nurseries] should allow 2.5 to 3 sq. ft. per pig, with 12 to 20 pigs per pen. ... Nurseries that are expected to produce 55-lb to 65-lb pigs for finishing should be designed to provide 2.8 to 3.2 sq. ft. per pig."
118. van Liere, D.W.: The significance of fowls' bathing in dust. Animal Welfare 1 (3): 187-202, 1992 (July).
"A chronic deprivation of adequate litter leads to an uncontrollable condition of the lipids on the integument and an abnormal development of dustbathing. Such a deprivation therefore reduces animal welfare. Moreover, it is suggested to be costly."
119. Van Liere, D.W., Kooijman, J. and Wiepkema, P.R.: Dustbathing behaviour of laying hens as related to quality of dustbathing material. Applied Animal Behaviour Science 26: 127-141, 1990.
120. van Putten, G.: Welfare in veal calf units. Veterinary Record 111: 437-440, 1982a.
121. van Putten, G.: Handling of slaughter pigs prior to loading and during loading on a lorry. In Transport of Animals Intended for Breeding, Production and Slaughter, Moss R. (ed.), The Hague:Martinus Nijhoff, pp. 15-27, 1982b.
122. van Putten, G.: The pig: A model for discussing animal behaviour and welfare. Applied Animal Behaviour Science 22: 115-128, 1989.
123. van Putten, G. and Elshof, W.Y.: The lying behaviour of veal calves up to 220 kg. In Welfare and Husbandry of Calves: A Seminar in the CEC Programme of Coordination of Research on Animal Welfare. Current Topics in Veterinary Medicine and Animal Science, vol. 19, Signoret, J.P. (ed.), The Hague:Martinus Nijhoff, pp. 83-98, 1982.
124. Van Rooijen, J.: Genetic adaptation and welfare. International Journal for the Study of Animal Problems 4: 191-197, 1983.
125. Vansickle, J.: Outdoor farrowing with all the modern conveniences. National Hog Farmer: 12-15, 1987.
126. Vestergaard, K. and Hansen, L.L.: Tethered versus loose sows: Ethological observations and measures of productivity. I. Ethological observations during pregnancy and farrowing. Annales de Recherches Veterinaires 15: 245-256, 1984.
127. Warriss, P.D.; Kestin, S.C.; Brown, S.N.; Knowles, T.G.; Wilkins, L.J.; Edwards, J.E.; Austin, S.D. and Nicol, C.J.: The depletion of glycogen stores and indices of dehydration in transported broilers. British Veterinary Journal 149 (4): 391-398, 1993 (July/August).
"This suggests that transported birds became dehydrated. Additionally, the depletion of body glycogen stores might be associated with the perception of fatigue."
128. Webster, A.B. and Hurnik, J.F.: Open-field assessment of behavioral phenotype within genetic stocks of the white leghorn chicken. Applied Animal Behaviour Science 27: 115-126, 1990.
129. Weisburger, J.H.: Progress in cancer prevention. Journal of NIH Research 3: 12-14, 1991.
130. Welchman, D. de B., Whelehan, O.P. and Webster, A.J.F.: Haematology of veal calves reared in different husbandry systems and the assessment of iron deficiency. Veterinary Record 123: 505-510, 1988.
131. Willett, W.: The search for the causes of breast and colon cancer. Nature 338: 389-394, 1989.
132. Wolford, J.H.: Induced moulting in laying fowls. World's Poultry Science Journal 40: 66-73, 1984.
133. Woolley, S.C., Borthwick, F.J.W. and Gentle, M.J.: Tissue resistivities and current pathways and their importance in pre-slaughter stunning of chickens. British Poultry Science 27: 301-306, 1986.
134. Woolley, S.C. and Gentle, M.J.: Physiological and behavioural responses in the hen (Gallus domesticus) to nociceptive stimulation. Comparative Biochemistry and Physiology 88A: 27-31, 1987.
135. Workman, L. and Rogers, L.J.: Pecking preferences in young chicks: Effects of nutritive reward and beak-trimming. Applied Animal Behaviour Science 26: 115-126, 1990.
|
