Heifer Rearing
Introduction
Dairy heifer replacement breeding is an important area in any dairy farm enterprise. However, it is often neglected by the farmers because of more pressing issues that occur when managing the farm. Hence, the dairy heifers do not grow at the required rate to hit expected targets at bulling and calving, causing them to lead an unproductive life. There will be a hidden cost to this affect across the productive life of the animal.
With some effort, by producing a heifer producing plan and monitoring the growth performance of the heifer calves against set targets and taking corrective measures, this will help improve the profitability of the farm.
Heifers are the future of dairy herd and they deserve to have a specialist rearing programme that incorporates the latest research and tools. This will undoubtedly repay the investment through higher milk production and a longer productive life.
Heifer Rearing
Traditionally, calf rearing systems involve feeding once or twice a day with low levels of Calf Milk Replacer (CMR), particularly in the first 3-4 weeks. This will result in low cost/kg liveweight gain (LWG) to weaning and also leads to lower LWG in the first few months. Hence, it may not be the most cost effective solution overall.
Dairy cows today are producing yields over 16% higher compared to 10 years ago. However, little attention has been paid on how to improve heifer rearing practices and successfully rear them in a manner which equips them to perform to their full potential. In order to improve the profitability over the lifetime of the dairy cow, today's heifer calf must be managed carefully since birth. By setting a goal of having high growth rates (>750g/day) up to weaning, versus lowest cost/kg LWG can pay significant dividends later on.
14.5% of heifers fail to reach their first lactation.
33% of heifers fail to reach their second lactation.
Poor fertility or poor 1st lactation milk yield are
the most common reasons for culling post-calving.
100% of heifers which calved down at 22-23 months
succeeded in reaching their second lactation and
spent 48% of their lives producing milk.
Heifers which calved down at 32-36 months spent
only 18% of their lives in milk.
(Wathes, Nottingham, 2009)
There is still a lot of room for improvements as a recent survey showed that 65-75% of heifers failed to calve down by 25 months of age. Another study reported that approximately 25% of heifer calves were growing at sub-optimal levels of <600g/day during their first 6 months. This was directly linked to the increased age at first calving as well as the reduced reproduction performance during the first lactation. On the other hand, improved early growth (600-800g/day) has a direct correlation of reduced mortality and lower age at first calving. There is also research that shows improved growth rates in the pre weaned calf is related to increased first lactation milk yield. Therefore, in order to achieve improved LWG, it is very important to regularly review the rearing system and also to measure the growth of heifer calves. This would enable the feed programmes to be modified to achieve target gains and hence, leading to long term benefits for the herd thus increasing profitability for the farm owners.
Equally important is to review the quality of feeds during early stage. It has been shown that increasing the milk replacer protein levels to 26% whilst limiting the oil % will enable higher growth rates with greater frame growth, but at the same time with less body fat and more lean tissue growth. The result of "fit but not fat" heifer is much desired as there is a direct link between higher body weight at calving and increased first lactation milk yield. However, with a "fat but unfit" heifer, it is more likely that the heifer will suffer from poor appetite post calving which would lead to an energy deficit and subsequent fertility problems.