HEIFERMAX

Raising replacement heifers is just one of the routine jobs done on a dairy farm. But how many people think about why they are raising those heifers? What is the ultimate goal and does the current path actually get to that goal?

 Heifers are not just raised to use up surplus waste milk or because people like raising calves. The goal is to raise heifers either to be sold as milk producers or to be retained on their home farm as replacements for cull cows. As such, farmers have either a moral or financial interest in ensuring that the heifers can produce as much milk as possible, given the feeding regime of the dairy herd they enter at calving. Therefore, the goal is to raise replacements which have been “programmed” early in life to be able to reach their genetic potential for milk production.

The best possible replacement heifer management outcome in terms of dairy profitability is for all the heifers to reach the farm’s pre-determined mating weight at 12-13 months, so that they calve by 24 months and remain as productive members of the herd for several lactations.

The most accurate measure of a farm’s calf and heifer management success is the percentage of heifers which calve by 24 months, produce well in their first lactation, get back in calf easily and remain as high producing cows for several lactations.

Three or four years ago, I was told by key industry authorities, that the cull rate of replacement heifers prior to their second lactation was 30-40% in Victoria and nearly 50% in Tasmania. Assuming the figures have not changed much in the intervening years, these cull rates would suggest that current rearing practices are not working very well. In other words, the current path is not leading to the goal. In other industries, this high failure rate would not be tolerated. A pig farmer would be horrified if he lost 40% of the gilts he was rearing as replacements; an airline would quickly go out of business if only 60% of its passengers arrived at their destination.

The main consequence of a high cull rate is economic loss.   One of the reasons that heifer management fails to achieve better results is that it is hard to quantify the benefits of improving heifer management. If, today, the dairy herd misses out on 50% of their grain ration, tomorrow, the results of that action show up in the vat. If heifer calves are not grown out well, there is not the same direct, visible result. If a farm always produces low quality heifers, it is very hard to quantify the exact amount of production loss stemming from poor heifer management.

Farmers select semen from specific A.I. sires to improve particular aspects of the herd. Depending on the areas which need improvement, this may mean using semen from a bull which leaves very good udders, particularly good feet and legs or increased milk solids. Whatever bull is chosen, though, production is unlikely to be sacrificed in the pursuit of good conformation. This means that heifers normally have the genetic capability to produce at least as much as their dams and probably more.

While genetics contributes to the amount of milk a heifer goes on to produce in her lifetime, there are other factors which influence her production level. One of these factors is the growth rate of heifers in the first 8 weeks of life, which research has proven has a big impact on lifetime milk production. Attempts to lift production usually focus on nutrition, pasture improvement and grazing management. Few people understand that by improving calf management, they could lift production by 1,000litres/head. Even less understand that improving calf management is more likely to save money than to cost money.

So, what can be done to reduce the high cull rates and therefore lower the cost of heifer raising? Farms which manage to have a heifer calf survival rate of close to 100% are doing a pretty good job.  However, although it may be a major milestone for some dairies, achieving it is still not the ultimate goal in rearing replacement heifers. Even farms which consistently achieve a low mortality rate (<1%) in their heifers should not rest on their laurels. The next step is to make sure that young calves are growing fast enough to reach their milk production potential.

Good growth rates in the first few weeks of life are achieved by :-

·         setting target growth rates for heifers from birth to first calving but particularly in that crucial first 8 weeks of life

·         feeding sufficient milk to achieve the target growth rates

·         monitoring to make sure that target growth rates are being met

·         having protocols in place to ensure  a high standard of care so that disease problems are minimised

·         having protocols in place so that there is consistency in all facets of calf management

·         monitoring to make sure that problems are detected before they cause major health issues.

Good growth rates in this early stage of life are necessary to allow heifers to reach their genetic capability for milk production. Failure to reach these target gains can limit a heifer’s future production by ≈ 1,000ℓ/lactation.

Prime lamb producers, racehorse breeders and pig breeders all ensure ad lib availability of high digestibility, high protein feed to their young stock. They do this because they know that, as a result of the unrestricted access to high quality feed, young stock will have high growth rates, good feed conversion efficiency and strong immune systems, resulting in low morbidity and mortality rates. These benefits translate into lambs & pigs which reach market weights early, with good frame size and ideal fat cover or into foals which have the muscle development and strength of bone to go on to win races.

A calf left to suckle its dam will drink between 6 & 14ℓ of milk per day, in several feeds and, by mimicking their mother’s behaviour, will begin to consume solid food quite early in life. The dam weans the calf gradually, over a period of weeks, as the calf becomes less dependent on her for nutrients, comfort and security.

For half a century, limit feeding dairy heifers has been the recommended practice.  Past research focussed on ways to facilitate early weaning. This was done with the aim of reducing weaning age by increasing starter intake and promoting rumen development, thus reducing the amount of milk fed to calves. There are several disadvantages of feeding limited amounts of milk:-

·         low growth rates compared with calves fed higher levels of milk or those reared by their dam

·         risk of higher calf mortality and morbidity rates

·         calves exhibit abnormal behaviours, suggesting that their welfare is compromised.

For over a decade the scientific community has questioned the logic of the recommendation for limit feeding. Several studies have investigated the effects of increasing the amount of milk fed to young calves; these studies have reported that calves fed more milk:-

·         were healthier

·         had higher weight gains

·         had better feed conversion rates

·         exhibited more natural behaviour.

Certainly feeding more milk reduces the consumption of calf starter and therefore rumen development in the first 2 -3 weeks of life, but is this important when we are talking about raising replacement heifers? We come back to the question of “what is the ultimate goal and does the current path actually get to that goal?” The extra milk or milk replacer may cost a little more in the short term but if it reduces the morbidity and mortality rates in pre-weaned calves and lowers the cull rate prior to the second lactation from, say, 40% to 20%, the small extra expense will be easily recouped.

Feeding heifer calves is no different from feeding lambs, piglets or foals; the economic benefits of doing a good job outweigh the costs. If pre-weaned calves can be raised with minimal health problems to meet target growth rates and if these early benefits can be maintained by using appropriate weaning methods and optimal post-weaning management it will improve their long term growth and productivity, which will flow on to benefit the finances of the farm.