Focus on basics to halt calving woes
With the start of mating getting ever closer, we should assess the success of last year's mating. As most farmers are around 6-10 weeks into calving, the percentage calved has been a common question at discussion groups.
Many would aim for 75-85pc calved at six weeks for a spring-calving herd and may often achieve this figure year after year, while others would fall short of this. However, it has become evident from many group discussions that there are more farmers dissatisfied with this year's calving rate and, as a result, last year's mating, when compared to their herd's performance in previous years.
When faced with a poor calving rate, it is human nature that we will try to find some fact in last year's mating that we can assign some blame for this failure. Common ones listed by farmers this spring have been minerals, especially phosphorous as cows were noted to be chewing stones, poor body condition score and animal health problems. The possible causes listed are stomach fluke, liver fluke or diseases such as IBR or BVD, inadequate bull power, or even shortage of pasture and tight grazing. Certainly, nutrition, genetics, body condition score, minerals, animal health, heat detection skills, reproductive infections such as BVD and Lepto, AI storage and handling, bull fertility and numbers can all have a detrimental impact.
One theory is the possibility that too much starch in the form of ration was fed during last year's mating because of a slow, cold spring.
The thinking is that this promoted insulin production, with high insulin levels having a detrimental effect on embryo quality. However, the reality is that we are in the business of commercial dairy farming, with limited measurement of all these factors, so we can't assign true blame to any particular issue. So, while I'm not suggesting that you shouldn't assess your performance and identify areas for improvement, it's a complex biological system and that's why it's time to focus on the basics and get them right.
A successful mating this year and compact calving in 2012 really starts with last year's heifer calves. Their rearing will have determined the quality of this year's maiden heifers. To establish and maintain a compact calving spread, it is important that the maiden heifers are mated at the same time, or even 7-10 days before the dairy herd.
Late-calving heifers have a lower chance of conceiving at mating and will either become late-calving cows or will be empty.
Therefore, heifers need to achieve target weights and have weight gain continually assessed throughout the mating period. We are aiming for 60pc of mature body weight at the start of mating. It's also important to make sure that the bulls selected for the heifers, whether natural or AI, have a low calving difficulty. Where natural service is used, monitor bull serving behaviour throughout mating to ensure they are serving correctly.