I’ve seen several articles recently which compare dairy cows to high performing athletes. Although they don’t inspire the same awe in the public audience or compete at the Olympics, the lactating cow’s metabolism works at an impressively high rate to convert feed into huge volumes of milk. Unfortunately, this incredible production comes at a cost and our dairy cows do suffer from a variety of common health problems, the most frequent of which I’ve been reading up on.
Lameness in some dairy herds can run incredibly high, affecting up to 50% of cows. As well as causing the cow suffering it also reduces milk yield and fertility, with conception rate lowered by 25% in some cases. These symptoms are expensive for the farmer, just as treatment can be, with MyDairyVet costing a lame cow’s veterinary expenses at £140+ and XLVets giving an average of £323.
A variety of factors including poor nutrition (especially where this causes acidosis), poor housing (poor quality, hard or wet floors and the accompanying reluctance of the cow to lie down) and ineffective foot trimming cause diseases of the foot. These include hoof lesions, sore ulcers, digital dermatitis, white line disease and foul in the foot, which in turn lead to lameness. Prevention is the correction of the above environmental factors, good maintenance of cow housing and tracks, breeding to bulls with good feet and keeping regularly updated records on cows’ locomotion scores. Trimming cows’ feet 1-2 times per lactation is recommended.
This is a bacterial infection of the udder, arising for a variety of reasons including injury or contaminated bedding. Contagious forms also exist and can be spread by dirty milking equipment. CIWF report that up to 70% of dairy cows may experience mastitis in a single year whilst in America the Journal of Dairy Science calls it the most expensive disease of cattle. Again, mastitis costs the farmer money as when infected cows are treated with antibiotics their milk must be discarded. The quality of their milk will also have dropped due to reduced calcium content and increased somatic cell content.
Prevention is similar to preventing lameness, including good nutrition, clean dry bedding and hygienic milking with pre- and post-milking products to clean the teats.
As with mastitis and lameness, poor welfare can cause infertility due to stress, nutritional issues and poor overall condition. Over the last few decades there has also been a trade-off in the genetic traits which breeders have selected for. As milk yield has risen a correlated decline in fertility has been observed. However not all selection on the dairy cow has led to increased health problems: for example, the udder of the modern cow has changes shape relative to cows of fifty years ago making it less prone to injury and mastitis.
The National Animal Disease Information Service (NADIS) suggest that in the UK infertility may be the worst economically-impacting health problem in dairy cows. This can be due to a longer calving interval (costing £2/day for every day it is increased by) and because infertile cows must be culled and replaced. Even cows with good health and a consistently high milk yield end up preferentially culled compared to lower yielding, poorer cows which are in calf; failure to conceive is the largest cause of cow culling in the UK.
There are of course many other issues affecting dairy cow health but here I hope I’ve managed to give a brief overview of some of the most common ones. If I’ve got anything wrong or missed a crucial point please let me know so I can find out more! Thanks for reading.