Dairy: Don't under-estimate the toll stress can take on herd performance
Published 07/10/2015 | 02:30
Dairy farmers have accepted the fact that reduced milk prices will be a feature of the business for the foreseeable future. The current milk price has dampened any thought of future expansion.
Many farmers have accepted that any expansion completed to date has placed an extra stress on both the owner and livestock.
As herd size increases in grass-based milk production systems, cows are walking further to graze grass. This has led to the construction of more 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 three litres per day in peak season when cows had to walk in excess of a mile to graze grass.
Farmers are now actively considering both the financial costs of expansion and also the ability to recruit skilled labour for dairy herd management.
Any sort of stress will reduce immunity against disease. Farm roadways become an issue in terms of lameness as bad weather increases the risk of foot injuries. Montellaro inter-digital dermatitis and consequent loss in body condition score (BCS) are all too frequent on many dairy farms.
Farm visits at this time of year are primarily associated with assessing reproductive performance. Accurate ageing of pregnancies, cows carrying twins, and the fertility status of empty cows are of primary concern.
With the super-levy disincentive gone, some farmers are planning to milk later into the season, including milking late calvers through the Christmas period. Accurate ageing of pregnancies will be essential if you plan to focus on an eight week dry cow 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 of cows that have either aborted or undergone late embryo/foetal death with mummification of the foetus in winter.
Early embryo deaths resulting in six and nine- week returns to heat can also be associated with the same stressors, but do not attract the same attention.
Neospora, salmonella, IBR, BVD, Johnes, and Leptospirosis are the primary 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.
Approximately three out of every five 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 limiting 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 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, farmers need to be vigilant about 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 will reduce the risk of foetal death and abortion in your dairy herd.
Dr Dan Ryan is a bovine reproductive physiologist and can be contacted at cowsDNA.com