Leonel Leal, Ruminant Researcher at Trouw Nutrition R & D, spoke on the second day of the international symposium that marked the official opening of Trouw Nutrition's new Calf & Beef Research Facility in April. The primary focus of his talk was to explain the idea of metabolic programming and how for ruminants, this process continues for the first two months of life. He also offered biological evidence that shows that elevating the plane of nutrition for neonatal calves has positive effects on weight, organ and tissue development. And he conveyed that further innovation in the field is coming soon, as Trouw Nutrition is currently studying such effects in a series of ongoing research trials.
Metabolic programming explained
Mr Leal began his presentation by explaining that the idea behind metabolic programming is that certain stimuli or early life events can have an impact on later physiological outcomes. It's a dynamic process and the effects are dependent upon a specific, critical window of opportunity. While such effects can be seen in many different species, in bovines the critical time period is the first few months of life, before weaning. During that timeframe, according to Leal, if calves are fed an elevated plane of nutrition, the metabolism can be programmed to impact lifetime production in a positive way. So, for example, as many studies have shown, we can see increased future milk production and reduced age at first calving in dairy cows as well as increased slaughter weight, carcass weight and feed efficiency in beef cattle.
The question for Leal and his colleagues, however, is how does this happen?
What evidence do we have that increasing the plane of nutrition leads to these kinds of positive changes?
In discussing the future impact of raising the nutritional inputs with bovines, Mr Leal pointed to ground breaking work by Fernando Soberon and Mike Van Amburgh in which they examined the organ development of young heifers after they were fed different planes of nutrition for the first 54 days of life.
source: Soberon and Van Amburgh, 2011
One group was restricted to 0.6 kg per day of milk replacer, while the other was fed an elevated plane of nutrition at 1.3 kg of milk replacer per day, which, Mr Leal points out, is actually closer to their natural level of appetite. At the end of the 54 days, there was a 33% difference in bodyweight. Additionally, the sizes of the livers and the mammary glands, even when adjusted for percentage of body weight, were also significantly larger in the calves fed a higher level of nutrition.
The weights of the kidneys of the LifeStart (or enhanced fed) calves as fresh weight were also significantly higher than the control calves.
And, when corrected as a percentage of body weight there was still a trend (0.05<P<0.1).
Mr Leal and his colleagues then had an opportunity to use samples from Soberon and VanAmburgh's study to look deeper into the tissues of the animals to figure out what had happened, and run gene expression profiles. Ultimately, they found differences between the two groups in organ development, tissue differentiation, energy metabolism, immune response and general metabolism, all simply as a result of how calves are fed in the first two months of life.
The need for ongoing study
Mr Leal went on to explain that as the Soberon and Van Amburgh study was limited by the fact that the animals were slaughtered at 54 days, it was important to follow such animals later in life to see if these kinds of metabolic differences would persist. So, Trouw Nutrition, through its LifeStart program, has embarked on a lifetime productivity study.
While the study is still under way, Leal reported that positive results have already emerged.
The calves that were fed an elevated plane of nutrition were already over 13 kg heavier than the restricted calves at 49 days of age.
And, while the two groups were very similar in terms of metabolites at day 2, at day 49 they were very different, metabolically speaking, leading to the conclusion that there was a strong dietary effect on the animals' metabolisms.
Ultimately, says Leal, when the natural state of calves is to take in 2 litres of milk, 6 to 7 times per day, it makes sense that restricting their feeding would have quite a big, negative impact on metabolism and production. Likewise, restoring their intakes to be closer to their natural state should also have a big impact, only in a positive way. And that is what Leal and his colleagues intend to find out. Stay tuned...