After weaning, calves may experience reduced growth. However this does not need to be the case, say researchers from Trouw Nutrition. The combination of feeding high levels of milk, weaning at a later age and doing it smarter, not only helps to prevent a weaning dip, but also results in a healthier calf at a later stage. And that has a positive impact on her lifetime production.
'Why do we feed our calves twice a day, and why so little?' This is the question that Leonel Leal, who together with Harma Berends, is involved in the LifeStart research programme into calf rearing at Trouw Nutrition, always asks scientists, students and cattle farmers. The answer is simple: because we traditionally milk twice a day and it is easier for the cattle farmer to supply the calves with the 'surplus' milk.
Leal explains that, 'Fortunately these days we are looking more closely at what a calf needs and what we can learn from the cow in terms of proper calf rearing.' And what is the most important lesson according to Leal? 'Definitely supply plenty of milk to the calf, especially in the first eight weeks of life. If you provide a calf with unrestricted access to milk in its first eight weeks, then it will drink up to sixteen litres of milk a day, divided over small portions. The two litres twice a day that many dairy farmers are used to is far too little for the growth and development of the calf.'
Crucial development in first two months
Leal's colleague Harma Berends underlined that a low milk-supply schedule affects not only the development in the first eight weeks of life, but also hinders the subsequent development into a dairy cow. 'There is an important relationship between youth growth, the calving age and results in the first two lactations of a dairy cow', she said concerning the importance of an effective feeding and weaning strategy for calves. 'It is precisely during the first eight weeks of its life that the animal's crucial development of organs and udder tissue takes place', explained Berends.
In relation to the optimum amount of milk and the best weaning strategy, Trouw Nutrition carried out research over three locations: a research facility in the Netherlands and a research and field-studies institute in Canada. 'The aim of the research was how we could reduce stress around weaning, at which age a calf would have the lowest decrease in development, and which strategy - gradual or abrupt - would work best', explained Leal.
The most important lesson from these studies is that young stock benefit from a high plane of nutrition, late weaning and unlimited dry feed during the weaning phase. 'In the past, we wanted calves to double their weight after two months, usually some eighty kilos,' said Eile van der Gaast, Product Manager - Young Animal Feeds at Trouw Nutrition. 'But a calf really has a good start when weaned at nine weeks with a weight of 90 to 95 kilos. This is essential for insemination to take place at 13 months, for calving at around 22 months and for greater milk yields. And this can only be achieved with a high plane of nutrition.'
High feeding plan for more energy
The young stock in the study were subject to either a high plane of nutrition, with four litres of milk replacer per meal, or a low plane of nutrition, with two litres replacer with each meal, which is the norm at many European dairy farms. Leal explained that a reduction in the feed – in the first four to six weeks this mainly involves a reduced milk supply – means that a calf uses almost all its energy from the feed to maintain life rather than for growth, organ development and supporting the immune system.
'The traditional idea behind this reduction is that calves that drink less milk switch to dry feed earlier and eat more. But that's just not true', he said. 'A calf will always start eating dry feed within two weeks, even when it has consumed milk, even in large amounts, in the same period.' Although the amount of starter intake in the late weaned group of calves is lower than the group that was weaned earlier, that equalises once both groups reach the age of 12 weeks (Figure 2).
Once the calf starts to eat solid feeds, the rumen and the related fermentation processes start to develop. 'The transition to different rations must take place as gradually as possible', said Berends. 'The change from digesting milk to fermentation of roughage and concentrates in the rumen is a major step. Rumen development needs time and a gradual approach. If rations are changed too quickly, the animal suffers stress, intestinal damage and the so-called weaning dip in growth', she added. 'That can be prevented by starting weaning later and gradually reducing the amount of milk supplied.'
A similar study into calves weaned at six or eight weeks shows that weaning at eight weeks results in a much smaller dip in the so-called available metabolizable energy – energy that is converted into growth – than weaning at six weeks. To ensure the transition from milk to dry feed runs as smoothly as possible, unlimited roughage and concentrate must always be available in addition to a high plane of nutrition / high milk supply. 'This increases both the growth and the total dry matter intake', Berends stated. Chopped straw is preferable due to its consistent quality and low sensitivity to spoilage. Ground roughage or roughage supplied as pellets are less suitable, as the physical structure of the roughage is important for the ruminant activity and development of the rumen.'
Working with protocols
Finally, the researchers give some advice. 'LifeStart research suggests that calves fed according to the protocols in our research programme have fewer health problems and a very low mortality rate', said Berends. That is an indication that standardised rearing – with sufficient and high quality colostrum, a gradual reduction in milk, sufficient roughage and concentrates and fresh drinking water – almost always contributes to a better development of young stock. She adds: 'It is valuable for every dairy farmer to manage calf rearing using protocols.'