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15th December, 2017

Stress and Disease Management in your Dairy Herd

The Annual National Ploughing event heralds not alone the largest outdoor event in Europe but a time of change in seasons with shorter days and reduced grass growth rates.
Dairy farmers have accepted the fact that reduced milk prices will be a feature of the business for the foreseeable future. The current price of milk has dampened any thought of future expansion. Many farmers have accepted that any expansion completed to date has placed an extra stress on both employers and livestock.
There is a reality that as herd size increases in grass based milk production systems, cows have to walk further to graze grass. This expansion has been associated with an unusual incidence of road underpasses and farm roadways to access grass.
Zero grazing has been introduced on some farms to reduce the amount of walking required and where farm fragmentation is a limiting factor. One client informed me that milk production dropped by 3 litres per day in peak season when cows had to walk in excess of a mile to graze grass. Farmers are now actively looking at their business models with consideration for both the financial costs of expansion and also the ability to recruit skilled labour passionate about the management of their dairy herd.
Any form of stress will reduce the ability of the immune system to cope with disease. Farm roadways become an issue in terms of lameness as inclement weather increases the risk of foot injuries. Montellaro inter digital dermatitis and consequent loss in BCS are all too frequent on many dairy farms.
Farm visits at this time of year are primarily associated with the need to get a full picture of reproductive performance. Accurate ageing of pregnancies, cows carrying twins, and the fertility status of empty cows are of primary concern.
As super levy no longer pertains, farmers plan to milk later into the season with some farmers considering milking late calvers through the Christmas period. Accurate ageing of pregnancies will be essential if one plans to focus on eight week dry cows periods. It is also essential to focus on the BCS of the cows. Low cost systems lend themselves to an increased risk of cows losing BCS at this time of year. This will have an adverse effect on next year’s breeding season.
Scanning cows at this time of year presents more cases where cows have either aborted or undergone late embryo/foetal death with mummification of the foetus in winter. The physical nature of these events set off alarm bells with farmers as they want to know the causative factors. Early embryo deaths resulting in 6 and 9 week returns to heat can also be associated with the same stressors, but do not gain the same attention.
Neospora, salmonella, IBR, BVD Johannes and Leptospirosis are the primary sources disease related causes of abortion/late foetal death. Our database encompassing the smartscan experience has also identified that multiple pregnancies are a significant cause of later foetal death and abortion. It is worth noting that approximately 3 of every 5 sets of twins in early pregnancy will not survive to full term.
Of the disease related causes of foetal death Neospora is the most frustrating as biosecurity and lack of a vaccine are binding factors in disease management. In a recent case study involving 178 cows we identified 35 cows with either mummified pregnancies or recently aborted. This was also associated with poor reproductive performance as only 112 cows were scanned pregnant based on a 14 week breeding period.
Neospora is the primary cause of abortion in the UK. It is a disease warranting increased attention as the offspring from Neospora positive cows can become carriers. Dogs and foxes are the intermediate hosts. Preventing access to afterbirths is the weak link in disease management. As dogs and foxes move from farm to farm it is in the interest of the industry that all farmers are vigilant in management of afterbirths.
Cows will be housed by night over the next few weeks. Prevent dogs and foxes gaining access to feeding areas. We have cases where Neospora contaminated dog faeces was removed from the face of a silage pit, mixed in a diet wagon with a consequent abortion storm in a group of dry cows.
In conclusion, stress management biosecurity and vaccination programmes where warranted will reduce the risk of foetal death/abortion on your dairy herd.
Dr Dan Ryan is a bovine reproductive physiologist and can be contacted at www.cowsDNA.com
Article written by Dr. Dan Ryan for the Farming Independent 8th of October 2015