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0608 PD: Science-based knowledge for animal welfare

Marina A. G. von Keyserlingk and Daniel M. Weary Published on 14 April 2008

Recent interest in animal welfare stems often from concerns related to intensive farming techniques.

In many modern farms, especially in the industrialized world, dairy cattle are housed indoors, a system perceived by some as “unnatural” as it provides limited space and often a limited ability to engage in some natural behaviors. Although concerns are frequently brought to public attention by clear acts of cruelty, as was the case in the recent horrific video images from the California slaughter plant, concerns also apply to widespread and accepted industry practice, and focus upon whole “systems” of housing and management.

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Issues surrounding animal welfare usually involve three types of concerns: the biological functioning of the animal (such as its health or productivity), how the animal is “feeling” (such as the amount of pain it is suffering) and the ability of the animal to live a “natural” life.

Veterinarians and producers are typically most concerned with the biological functioning of the animal and generally focus on disease, injury, growth rates and reproductive problems. However, many consumers tend to be concerned more with the affective state, or emotions of the animal, and focus upon whether the animals are suffering from unpleasant feelings such as pain, fear or hunger. For others (including many consumers of organic products), a key concern is whether the animal is able to live a relatively natural life. For the dairy industry, this last issue is especially controversial, seeming to imply that we should abandon decades of technical progress. For advocates, a more “natural” way of rearing dairy cattle typically consists of delayed separation between cow and calf, giving cows access to pasture and reducing the use of high-grain diets.

Different people can thus reach opposite conclusions about the relative advantages of different housing systems by favoring different welfare indicators. Clearly the best solutions will be those that address a variety of concerns and are based on solid scientific information about animal welfare. Taking this approach we discuss some of the major welfare concerns faced by the dairy industry that have also been the topic of recent scientific research.

Feeding and housing dairy calves
Changes in both management and housing of dairy calves result in new challenges for producers and their calves that require innovation and new research. One of the major concerns for animal welfare is the high level of mortality and morbidity among young calves. Although one of the most important practices in calf-rearing is the provision of adequate colostrum, more than 30 percent of calf deaths are associated with poor transfer of immunoglobulins to the calf. Thus, even in cases where the science is clear, good practice does not always follow.

Another public concern is individual housing of calves and the associated restriction of social contact and movement. This practice is effectively banned in the European Union for calves over 8 weeks old. In North America, most dairy producers continue to rely on individual housing, but some are now using group housing, in part because the reduced labor needed for calf-rearing, especially when used with automated milk feeding equipment. Likely a more serious welfare issue is the underfeeding of most milk-fed calves. Recent research has shown that calves prefer much higher milk allowances than they are typically provided, and providing this extra milk provides for improved growth, health and more efficient weight gains. An added advantage of allowing higher milk allowances, especially when providing milk via a nipple, is that it reduces the tendency of calves to suck on each other, in turn making calves easier to group house.

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Health of transition cows
The “transition” phase (3 weeks before calving to 3 weeks after calving) is one of the times in dairy production where risks to cow health (and hence welfare) are highest. High milk production likely places extra demands on the cow, leading to an increased risk of disease. Metabolic diseases such as ketosis and clinical hypocalcemia (milk fever) are common during transition, and susceptibility to infectious diseases like metritis also peaks at this time.

The high demand for nutrients at the onset of lactation seems to be a prime factor leading to these diseases. Despite decades of nutritional and epidemiological work, the incidence of disease around the calving period in lactating dairy cattle remains high, showing the need for a better understanding of the management factors leading to illness and developing better tools for identifying which cows are ill or are most likely to become ill after calving.

Lameness and cow comfort
Lameness is a major welfare problem for dairy cows, and it is often the cows with the highest milk production that are most likely to become lame. Lameness results from infectious disease (such as digital dermatitis and foot rot) and hoof lesions (e.g., ulcers, hemorrhages, white-line separation) associated with metabolic challenges and physical injury to the hoof. Nutritional factors such as wet silage or high-grain diets can increase risks, but frequently overlooked management factors (such as the use of concrete floors, zero-grazing and uncomfortable stalls) are normally the main culprits. Recent research has generated much new information on cow comfort, providing the basis for improvements in lying stalls, standing surfaces and feeding areas that are known to reduce the risk of lameness.

Compounding the problem is that producers find it difficult to identify animals at the early stages of lameness, likely because dairy cows remain stoic unless injuries are relatively severe. Part of the difficulty in identifying lame cows may come from the fact that herd sizes are increasing, leaving producers less time to spend watching their animals. This has led to interest in automated means of detecting lameness through changes in how cows distribute the weight among the four limbs, either when standing or walking.

Painful procedures
Causing pain to another is typically considered the most abhorrent of activities. Painful procedures remain part of the everyday business of dairy farming, but new scientific studies are showing ways that this pain can be reduced or avoided. For example, dehorning calves is so widely recognized to be painful that it is considered one of the main models for the scientific study of pain in farm animals. These studies have shown that the use of a local anaesthetic provides some immediate relief. The use of non-steroidal anti-inflammatory drugs, in addition to a local anaesthetic, can control the pain that typically occurs in the hours that follow a burn injury. Animals respond to both the pain of the procedure and to the physical restraint and even calves dehorned using pain-relieving drugs still need to be restrained. The use of a sedative can essentially eliminate calf responses to the administration of the local anaesthetic and the need for physical restraint during dehorning. Caustic paste is an alternative method to hot-iron dehorning. This method is still painful for the calves, but recent research has shown that this pain can be controlled using only a sedative. The take-home message is that pain due to dehorning and other procedures can be managed, often with little effort or expense.

Procedures like dehorning are hard to avoid for most dairymen, but some management procedures may not provide any real benefit for the farm. For example, a series of well-controlled studies, examining thousands of cows on many commercial farms, have found no benefit in cow cleanliness or cow health to tail-docking. Here the science is clear – tail-docking provides no benefit to the farm, but clearly harms the cows.

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In summary, new scientific research is providing a better understanding of the key welfare concerns for dairy cows and calves, as well as how these concerns can be addressed. The best examples provide clear benefits for the animals, but they also improve the lives of dairy producers by reducing costs, improving performance and improving the quality of interactions with the animals they care for.

Marina von Keyserlingk
Associate Professor of Animal Welfare at the University of British Columbia

Marina A. G. von Keyserlingk and Daniel M. Weary for Progressive Dairyman

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