The importance of condition scoring

摘要

Body condition score has a major impact on the productivity and probability of dairy herds. Discussion group facilitator and consultant Mary Kinston BSc Agriculture PhD provides a guide to achieving key targets. Dairy cows that calve in the right bodycondition, that lose no more than 0.5 of a body condition score (BCS) after calving, and are gaining weight, will maximise dry matter intake, milk production, reproduction function, cow health and welfare. Therefore, BCS has a huge bearing on a dairy herd's ability to be productive and profitable. Research has also indicated that the condition of a cow in early lactation will also influence the sex of future calves and the productive and reproductive capacity of heifers yet to be born. Yet while the importance of having cows hitting BCS targets has been well known for decades, its assessment and, subsequently, its management, is one of the most under-utilised techniques applied on the dairy farm. Irrespective of the farming system or cow genetics, milk production is optimised when a mature cow calves at a BCS between 3 and 4. For example, a study by McNamara et al in 2001 showed that cows that calved below a BCS of 2.75 produced, on average, four litres per day less during the first eight weeks of lactation, compared to cows that calved at a BCS of 3. Other studies have also shown negative effects on the anoestrus period, being 8-10 days longer, and the pregnancy rate to first service being 7% less. Another consequence of these negative effects on reproductive performance is the reduction in milk production in the following year due to a prolonged calving interval. The milk-production double-whammy! However, production benefits do decline with increasing body condition and increase the risk of metabolic health disorders at calving when the BCS increases beyond 3.25 in a mature cow, and 3.5 in first and second calvers. So,for a production system to run smoothly, BCS does need to be managed, rather than become a result of either good or bad silage, high or low milk price, and the old constraints that milk quota posed.