As for most farmers spring is our busiest time of year, especially for calvings, so I thought this month I would discuss the pre breeding checks we can offer in order to make sure you retain the most fertile heifers for your breeding herd. Pelvic measuring in heifers is a technique we can use to improve calving ease. It can also be a useful tool when deciding which heifers you want to use as replacements in a dairy or beef herd.
Dystocia or difficult calving is estimated to occur in about 10-15% of first-calf heifers and in 3-5% of mature cattle. The most common cause of dystocia is fetal-maternal disproportion or in simple terms the calf being too big for the size of the heifer. The financial implications of dystocia total much more than just veterinary costs - the hidden costs add up too. A harder calving means a longer recovery and may mean it is harder to get her back in calf, reducing productivity and profitability. Difficult calvings have an increased risk of metritis/ prolapse and therefore calf survival is also reduced. So, anything we can do to make calving easier is vitally important.
The most common cause of an oversized calf is bull selection. Choosing a bull with good direct calving ease on EBV or £PLI figures is the first step you can take to reduce calving difficulty in heifers.
There are several other factors that also contribute. Body condition of the heifer at the time of breeding and calving is very important. Fat heifers or very thin heifers will have a much higher risk of calving difficulty, so it is important to have appropriate nutrition throughout pregnancy to ensure growth of the heifer to a mature adult frame without her becoming fat.
Pelvic size in heifers also contributes to calving ease and has been a popular topic recently, we are increasingly asked to carry out pre-breeding checks and pelvic scores on farm.