Het belang van een verhoogde levensduur van de koe

Jeffrey RushenJeffrey Rushen, adjunct professor in the Animal Welfare Program at the University of British Columbia, Canada.

Removing the causes of involuntary culling can significantly improve animal welfare and farm profits, and the research that shows how to do this exists. But it has proved to be a challenge to get this knowledge implemented on the farms. Many producers do have a low involuntary culling rate, which means that their housing and management practices are keeping health problems under control. To motivate producers to change, Jeffrey Rushen suggested monitoring the cows, keeping records and benchmarking with other farms. He also underlined the importance of companies like DeLaval to get the information out to the farmers.

A turnover of cows on a dairy farm is to be expected, as farmers remove cows because of low milk production or sell them. However, much of the low longevity of dairy cows results from involuntary culling because of poor health or fertility problems. High rates of involuntary culling on a farm are a sign of poor animal welfare and are very costly to dairy producers. The main causes of involuntary culling are the same in different parts of the world, although proportions might differ: reproduction, udder health and lameness. A reduction of these causes of low longevity leads to improved animal welfare and farm profitability.

Implementation of what science has shown to be best management practices  can result in significant improvements in animal welfare and farm profitability. Many producers already have low rates of involuntary culling, showing that their housing and management practices are keeping these health problems under control.

Lost revenue

A high rate of involuntary culling can have a marked, negative economic impact on the farm. Higher yielding cows tend to be more likely to suffer from problems leading to culling and high rates of involuntary culling may mean that other lower producing cows remain in the herd to maintain replacement rates. Also, the health and welfare problems that lead producers to cull their animals are a very important cause of lost revenue for producers.

Involuntary culling for these health/welfare problems is only the tip of the iceberg because the actual prevalence of the underlying health and welfare problems can be considerably higher than the rate of culling. In Canada 2% of the dairy cows are culled because of lameness, while the actual prevalence is above 20%. The prevalence of hoof lesions is even higher, averaging 46% in cows kept in free stalls. In the USA, an average of 20%-55% of dairy cows are lame at any one time (depending on the region), even though only about 4% of dairy cows are actually culled for lameness. The same pattern can be found for mastitis: in Canada about 4% of all cows are culled on a yearly basis because of mastitis, high SSC or poor udder health, but estimates of mastitis treatment incidence are around 23 cases/100 cow years.

Many studies have been done to estimate lost revenue as a result of diseases such as lameness or mastitis, and most of them conclude that a cost of several hundred dollars per case is not unreasonable. For example, a producer in the north east of the USA with an average prevalence of lameness of 55% may be losing over US$10,000 (7,400 EUR) per hundred cows. Based on a Canadian  estimated cost of lameness of 308 US$/case, Canadian dairy farmers were estimated to be losing over $6,000 (4,400 EUR)/100 cows/year on average, while the farms with the highest lameness prevalence were losing over US$20,000 (14,800 EUR). Therefore it is important for financial reasons that the dairy industry reduces the incidence of the health and welfare problems that lead to a high involuntary culling rate. Although some financial investment must be made to reduce the prevalence of these causes of involuntary culling, the long term financial rewards have been shown to outweigh these costs.

Differences between farms

There is a huge variation in producers’ ability to manage these risk factors and health problems. The average rate of mastitis treatments on Canadian dairy farms is 23 cases/100 cow years, but the rate varies across farms from 1% to 97%! The large variability from farm to farm suggests that certain housing or management methods may be risk factors while some producers have found ways to manage and house their animals so as to have a low incidence of these problems.

Risk factors

Zero-grazing increases the risk of lameness as well as other health and welfare problems such as metritis and hock injuries. It should not be necessary to give all cows access to pasture in order to ensure their well-being; it could simply be that the ideal indoor-housing for lactating cows has not been designed yet, at least not on most farms. Zero-grazing increases the risk of cows going lame and therefore places greater responsibility on the producer to adopt housing and management techniques that allow cows to be kept indoors without going lame.

Any factors that increase the time that cows spend standing, especially on wet concrete floors or reduces the comfort of the lying stalls, appear to increase the risk of lameness. If cubicles are too small or too few, or bedding is insufficient, cows will spend less time lying down. They will stand on mainly hard, concrete, sometimes wet, floors and this can lead to lameness.

Changes for improvement

Many of the changes needed to reduce the causes of involuntary culling do not require major changes to housing. There are simple, well documented solutions that can dramatically improve the welfare, health and longevity of the animals.

Research has found that sand or deep bedding on mattresses reduce hock injuries, slippery concrete floors increase chance of knee injuries and higher feed rails reduce the risk of neck injuries. Sand bedding has been shown to be associated with lower prevalence of lameness, but switching to sand bedding requires significant changes to the buildings, and sand is not always the best option. Simply adding more straw or sawdust bedding can go a long way to reduce hock injuries. On farms with mattresses and no use of bedding, nearly 80% of the cows suffered from hock lesions, whereas on farms with more than 2cms of bedding the prevalence of hock lesions was 31%. Although mattresses are associated with a high prevalence of hock lesions, adding mattresses to concrete based stalls can greatly reduce injuries to the knees. Other injuries can also be reduced by relatively simple changes in housing: increasing the height of the feed rail at the feed bunk to above 140cms from the floor greatly reduces the risk of neck injuries. Significant reductions in cow injury rates can be achieved without major changes to the dairy buildings.

Consumer concerns

These animal welfare issues can lead to publicity problems and concerned consumers. This in turn can lead to a contraction of the market, if people choose not to consume dairy products. There is a real economic risk in this, and if the reasons behind the low longevity problems are reduced it will improve the animal welfare, the farm profitability and lead to long term sustainability for the dairy industry.

Knowledge transfer

A considerable amount of research has identified the main risk factors for the illnesses that lead to involuntary culling, and the negative economic impacts of these problems are well known. Still it remains a challenge to transfer this knowledge to the farmers, and companies like DeLaval has a huge role to play in getting this information out to the producers.

Having clear animal welfare standards that have been developed by the dairy industry itself, combined with greater use of benchmarking to allow producers to compare themselves with their peers, can help overcome these challenges. The producers might not be aware of what is possible, where the strengths and weaknesses of their farms are.  Benchmarking with others encourages producers to make improvements, and it also helps to document changes and progress over time.

An animal welfare assessment done in Canada recently showed that as much as 70-72% of the farmers subsequently said that they had made changes on the farm because of the benchmark and assessment they had participated in. This shows that an advisory tool including assessment and benchmarking can be a promising way to help producers adopt methods to improve the health and profitability of their herd.

Key messages:

  • High rates of involuntary culling on a dairy farm because of illness or reproductive problems occur because of poor cow welfare and reduce the profitability of dairy farms. Removing the main causes of involuntary culling will lead to improved animal welfare and improved farm profits.
  • Although world-wide rates of involuntary culling are high, some producers have a low rate showing that they have adopted housing and management practices that control the prevalence of the underlying health problems.
  • Calf illness and mortality is also a contributor to reduced longevity and poor calf management can have a negative impact on the cow’s later productivity.
  • Research has identified some of the main risk factors in indoor housing that lead to lameness, injury, and illness in dairy cattle but a challenge is getting this information implemented by producers.
  • Having clear, industry-led animal welfare standards, and greater use of benchmarking of farm performance, holds promise as a way of increasing the uptake of knowledge by dairy producers to improve the welfare of their animals and reduce involuntary culling

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