Description

This webinar considers the importance of calf growth rates, focussing on pre-weaned dairy heifers. Future performance of animals in the herd is optimal with a first calving age of about 24 months but very few UK farms currently achieve this. For a Holstein-Friesian type animal to calve successfully at 2 years, this requires an average growth rate of around 0.8 kg/d from birth. The milk feeding period is critical as heifers which grow poorly at this stage are likely to have delayed puberty, later calving and a shorter survival time in the milking herd. Key factors affecting calf growth rates include feeding policy, health, the environment and stress. With respect to feeding, the quality and quantity of the milk provided and the feeding method and frequency are all important. Most UK heifers do not achieve pre-weaning growth rates of >0.7 kg/d because they receive too little milk. Environmental temperature is an important consideration as nutrient requirements increase when calves are kept below their thermoneutral zone, which is <20oC in the first three weeks of life. Growth rates are also reduced when calves are in poor health. Diarrhoea and respiratory disease are most prevalent. Scours is best prevented by excellent hygiene in both housing and feeding equipment. Respiratory disease can be reduced by achieving good passive transfer, keeping calves in stable groups and feeding more milk. Farmers should be encouraged to be proactive in measuring growth rates so that any issues can be identified early and preventive measures taken. Weigh bands are the simplest method in pre-weaned calves with scales used for older animals. Although feeding more milk may appear expensive at the time, the pre-weaned period is quite short and only accounts for about 11% of the total costs of rearing a heifer to the point of calving. The cost of feeding sufficient milk to achieve growth rates >0.7 kg/d at this early stage should be recouped later as health and survival rates should improve and the length of the rearing phase overall can be reduced.