Abstract/Summary

The rearing period has a key influence on dairy cows, affecting their future fertility, longevity and lifetime milk production. An age at first calving (AFC) close to 2 years (23-25 months) is optimum for economic performance as it allows sufficient growth while minimising the non-productive period and it also facilitates a seasonal calving pattern (Wathes and others 2014). In order to calve at 24 months, replacement heifers must have reached about 55% to 60% of their mature body weight at first service so that they can conceive by 15 months. For a typical Holstein type heifer this requires an average growth rate of about 750 g/d. Ensuring that calves are born into a clean environment and then receive an adequate colostrum intake are both beneficial first steps towards rearing healthy calves (Patel and others 2014). A volume of 3-4 L colostrum (approximately 10% body weight) containing >50 g immunoglobulin (Ig)G/L and with a low bacterial count should ideally be fed within 2 h of birth and no later than 6 h. Adequate intake cannot be assumed when calves suckle their dam. New born calves have little body fat, so are also highly dependent on the lipids and lactose in colostrum as a source of energy. Other beneficial ingredients in colostrum include minerals, vitamins and antimicrobials. Despite the importance of colostrum, a recent survey of 102 UK dairy farms revealed that only 43% checked that colostrum quality was adequate and took appropriate steps if it was not (Boulton and others 2015). Risk of subsequent mortality and morbidity are increased by having a difficult calving and/or subsequent exposure to unhygienic facilities, cold stress or inadequate feed intake. We found that about 3.4% of heifer calves currently die within their first month, but this rate varied from 0-12% between farms, reflecting differences in management (Brickell and others 2009). Feed accounts for nearly half the costs associated with pre-weaning management. Current UK nutritional practices during this period are extremely variable. Our survey found that reconstituted milk replacer (55%) was most common followed by whole milk (18%). This was usually fed warm by bucket (36%), multi teat feeder (24%) or automatic feeder (20%) The average volume of milk fed to a heifer calf per day was 4.58 ± 1.33 L but with a wide range of 2.1 to 12.6 L (Boulton and others 2015). These lower amounts would be insufficient to maintain a good growth rate particularly in temperatures below thermoneutral where more nutrients are required for maintenance. Previous studies have, however, found that heifers provided with intensified feeding programmes attain puberty, conceive and calve earlier and produce more milk during their first lactation (Wathes and others 2014). Weaning occurred at a mean age of 62 ± 13.3 days (range 42 to 112) and was most commonly based on age (53%) rather than size (19%) or feed intake (17%). This may also lead to later problems as there will be a post weaning growth check if calves are not consuming sufficient solid feed before weaning. In summary, educating dairy producers to invest adequate resources into pre-weaned calf management offers scope for significant improvements in calf health and welfare and should pay long term dividends by providing better replacements into the herd.