Leonel Leal explains the epigenetic effect and the importance of investing in improved nutrition for calves.
To better understand how environmental factors can effect outcomes in nature, there's no better place to look than inside the beehive. All female bee larvae contain the same DNA—in fact they are genetic clones—and yet there is significant differentiation between the queen and worker bees. As they are clones and therefore both groups are exclusively female, (the reproducing males are called drones), this difference is not accounted for by sex. So, how can two clones become different? The answer is found in external or environmental factors.
While two organisms may be genetically identical, the force of external factors on how their genes function (a phenomenon studied further in the science of epigenetics) can be substantial. While all bee larvae are fed royal jelly for the first three days of life, for the queen bees, the key external factor kicks in on day four, when they continue their ingestion of that royal jelly, at a feed rate 10x higher than worker bees, throughout their development! While the queens eat large quantities of royal jelly, the worker bees eat regular, less fortified food, and in much smaller quantities than the queens do. This one critical difference determines lifespan (queens live to be two or three years old compared to worker bees who are lucky to live two or three months) and size (queen bees are twice the size of worker bees). Bees are indeed an amazing example of how environmental conditions can impact outcomes, to a far greater degree than genetic determinants.
So, what does this have to do with calves and calf nutrition? A great deal, according to Leonel Leal, Ruminant Nutrition Researcher at Nutreco. Mr. Leal points out that while the dairy industry has been investing enormous amounts time, money and effort in the possibility of increasing the genetic potential of herds, they have yet to realise the possibilities involved in investing fully in environmental effects, such as improved nutrition. Mr. Leal refers to the fact that the current data and meta-analysis on early calf (pre-weaning) nutrition and its subsequent effect on milk production points out rather clearly that it's environmental (or nutritional) changes that are having the greatest positive impact on production, and not genetic changes.
Mr. Leal underscores the issue by pointing out that while in nature, calves suckle in an unlimited fashion from their dams,a big challenge regarding the way the dairy industry currently feeds calves is the seemingly restrictive nature of artificial feeding systems. He feels that if the industry were able to get closer to the way calves are fed in nature, meaning feeding elevated levels of nutrition with greater meal frequency wherever possible, higher levels of milk production would occur. With this environmental change, calves would be able to produce in the way that they were designed for, instead of the encumbered long-term performance of the past, which was a product of negative and restrictive programming. By increasing the nutritional inputs, Mr. Leal believes that as calves age, they could get closer to reaching their true production potential and perhaps be the new "queens" of the dairy!