Spring is almost upon us and attention is turning to the approaching calving season. Although this is an extremely busy time of year, it is well worth putting a big effort into rearing newborn calves to the best of your ability. After all, the heifer calves born today will be entering the herd as replacements in 2014.
Research has shown that if heifers are reared properly and achieve target weights at designated times during their first two years of life (ie, six months, breeding, pre-calving), they go on to be more productive and stay in the herd for a greater number of lactations. This article aims to try and make this year's calving season as successful as possible.
The benefits of feeding an appropriate amount of colostrum at the correct time are well known -- use the first milk from the cow and feed the calf three litres within the first two hours of life. However, feeding management after this first feed is not addressed as frequently.
Traditionally, dairy calves have been offered around 4-4.5 litres of milk a day, which is about 8-10pc of their bodyweight. This amount of milk will supply just enough energy to meet their maintenance requirements until they start to eat concentrates, therefore weight gains of only 0.2kg/day can be expected. Furthermore, it means that these calves do not have enough energy to fight disease or any other stressful situations that they may encounter.
If this feeding strategy is compared to a suckler calf, large differences are evident. Suckler calves have an ad-lib milk supply and can drink up to 20pc of their bodyweight each day. This can equate to milk intake of up to eight litres for a 40kg calf, resulting in weight gains of about 1kg/day being achievable.
Thus, it is clear that in order to ensure dairy calves are growing well, are strong and healthy and well able to fight any stressor that comes along, they should be fed 13-15pc of their birth weight in whole milk or high quality milk replacer. This level of feeding should support weight gains of 0.5-0.6kg/day.
The table outlines appropriate feeding levels for different breeds.
One question that frequently arises among farmers is in relation to the method of feeding: which is better -- a nipple or bucket?
Feeding calves from a nipple is more natural because it mimics the suckling behaviour they would use if they were kept with their mother. Furthermore, the abomasum (fourth stomach) is the only stomach working in the newborn calf. For milk to enter the abomasum, the oesophageal groove has to close by reflex so that milk does not spill into the rumen. This works best if the calves are suckling from a teat or nipple. Drinking from the nipple also takes longer and helps the calf satisfy their suckling urge.
However, calves can usually be fed successfully from a bucket after they are trained. The feeding method has been shown not to have a major impact on weight gain.
Once-a-day milk feeding is a labour-reducing method of feeding milk to calves. Studies have shown that similar weight gains are achieved when calves are fed milk once a day compared to twice a day.
Once-a-day milk feeding should not be introduced before three weeks of age, as the abomasum of the calf is not yet big enough to handle large volumes of milk. If calves are being fed their milk once a day, they should be thoroughly checked a second time during the day and their concentrate feed offered at this point.
As a general rule, waste milk should not be fed to calves. Waste milk is milk that would not normally be sent to the co-op for processing. Essentially, it is milk from cows that have been treated with antibiotics and whose milk is within the specified withdrawal period. It also includes milk from cows with a high somatic cell count.
Milk from cows that have been treated with antibiotics can contain residues of those antibiotics. If this milk is fed to calves it can:
-Reduce the amount of milk that the calves drink as the milk can taste a little 'off'.
-Lead to the development of bacteria that are resistant to these antibiotics. Therefore, if an outbreak of disease occurs and these antibiotics are used, they may not work effectively.
One strategy to allow use of waste milk for calf feeding is to pasteurise it. Pasteurisation involves exposing the milk to high temperatures for a period of time to reduce the amount of bacterial contamination.
However, this process needs to be completed within a few hours of collection so that the amount of bacteria in the milk does not increase dramatically.
The rumen of a newborn calf is very small and underdeveloped and does not contribute to digestion. To encourage early rumen development, the young calf needs to start eating starter concentrate and have access to fresh, clean, drinking water.
The intake of a calf starter concentrate is the single most important factor in the development of the rumen. For this reason, calves should be offered fresh concentrate from an early age, even though they will only eat small amounts before they are three weeks old. The development of the rumen is important to ensure a smooth transition from milk feeding and minimise reductions in growth rates at weaning.
Calves fed a coarse starter mix eat more concentrate and have higher weight gains than calves fed pelleted starters. The coarseness of the concentrate improves the growth of the muscle layers in the rumen wall. In addition, if the coarseness of the concentrate is greater than 2mm, the calves will require no additional roughage source.
To avoid a check in growth rates at weaning, the recommendation is that calves should be eating at least 1kg of starter concentrate before they are weaned.
Ideally, calves should be weaned at a similar weight to ensure uniform groups that are easier to manage during the summer grazing season. Weaning should be completed gradually by reducing the volume of milk fed over a 7-10 day period.
If calves are being fed twice a day, changing to once-a-day feeding can reduce the milk volume, which will lead to an increase in starter concentrate intake and avoid a post-weaning weight gain check.
Animal Health Ireland's calf health technical working group has run a series of conferences in recent months addressing calf-rearing issues. The content of these conferences and the associated leaflets are available at www.animalhealthireland.ie