21 DECEMBER 2016
Achieving good fertility in dairy cattle requires very much a whole team approach bringing together overall management, veterinary input and nutritionist skills, Adam Collantine, Dugdale Nutrition dairy consultant said in Garstang.
“A fertility programme rally runs from heat detection through to two or three weeks after calving. Most dairy farmers are ideally looking for a 365 day calving index or as near as they can get. The cow is pregnant for about 280 days, so to achieve a 365 day index she needs to be back in calf in about 85 days but how practical is that?” he said.
Mr Collantine told the Dugdale Intelligent Feeding Forum meeting that assuming the cows’ uteruses could get in calf, key questions were whether all cows were coming on heat, this was being observed, the cows were being inseminated at the right time and were getting in calf.
Part of the issue here was simply watching cows for signs of heat and ensuring that whoever was doing this knew what to look for. Typically, cows were on heat for 12 hours of which standing heat and head mounting for about half this.
Some 90 per cent of cows on heat would mount each other but only about 40 per cent would stand to be mounted. Some 40 per cent would not show a standing heat. In addition cows did not show heats in temperatures of more than 21oC and duration tended to reduce as milk yields rose. Good, well lit housing was an important aid to observation of heat behaviour.
Records were important and it was worth remembering that pregnancy rates were a more reliable measure than conception rates in assessing group fertility as there was nowhere to hide in the figures used, he said.
Mike Murphy of Oakhill Farm Vets, Preston said: “Dairy cow fertility is a huge topic and we have all got to work together to improve different areas on different farms to get a gradual improvement in fertility. Studies all the way from the 1950s to the present time show cows giving more and more milk but with a lower first service pregnancy rate. Simply more milk means less fertility, but I don’t think things are as simple as that. Going back to the 60s and 70s yields were lower and fertility was better.
“I think that we need to look back at the 70s and what has changed on farms over the last 20-30 years with bigger farms, more cows, less labour on farms, people moving to more confined systems and less grazing herds. Even in really good set ups with good ventilation, good lighting, nice sand beds and cubicles with wide passages there have been problems with fertility.”
Mr Murphy said that there had also been fertility problems following moves to low input-low output non-grass systems in New Zealand as well as in grass only systems in Ireland. In the UK, NMR and Reading University were producing reports from dairy farms across the country with the 2015 figures showing small improvements in both health and fertility.
There were undoubtedly many factors, but these might include rejigging indices so selecting bulls for fertility, longevity and fitness traits as well as milk production. Each farm was different and it was important to identify the root causes of problems on individual farms. Certainly, he believed that routine vet visits about every two weeks would quickly pay for themselves in identifying and dealing with problems at an early stage.
Bringing the nutritionist’s contribution, Bill Hardman, Dugdale Nutrition’s technical manager the key aims of feeding in maintaining fertility were: to consistently achieve optimum body condition pre-calving but not to over feed energy in the dry period and should also aim to minimise clinical and sub-clinical milk fever.
High dry matter intakes in fresh cows helped minimise negative energy balance, think glucose (and starch), and don’t overfeed fat, said Mr Hardman.