Metabolic programming, otherwise known as neonatal imprinting, has been a subject of study in a variety of species for decades. At the heart of this line of inquiry is the question of whether health and growth can be optimized via particular methods of feeding and management during the first stages of an animal's life. Over the last 30 years, specific research into bovines and metabolic programming has been plentiful. If feeding and management techniques in early life do indeed influence neonatal health, growth and eventual production, as ongoing research suggests, the question becomes: What are the parameters necessary to achieve optimal calf health and growth that could, in turn, lead to optimal performance? Dr Cristina Yunta, in the literature review for her 2015 doctoral dissertation for the Universitat Autonoma de Barcelona entitled, "Impact of prenatal and neonatal nutrition on metabolism and future performance in dairy heifers,"1 gives an extensive overview of recent research related to both the short- and long-term effects of high quality colostrum feeding. She also examines how upping the quantity of milk fed pre-weaning relates to this very important question.
The effects of colostrum on health and metabolism
Colostrum is both rich in nutrients and bioactive compounds, such as hormones and growth factors. As maternal immunoglobulins cannot permeate the placenta, the importance of feeding newborn calves an adequate volume of high quality colostrum is widely understood. Dr Yunta found that to reduce the incidence of disease, 10mg of IgG/mL in calf serum 48 hours after birth is the common recommendation.2 Therefore, she posits that feeding four litres of colostrum immediately after birth is best. Additionally, she notes that veterinary costs are reduced when four litres of colostrum are fed instead of two litres.3
Dr Yunta examines not only the effects of IgG content in colostrum on neonatal calf health, but also other bioactive colostral factors and their influence on post-natal development, growth and performance. Bioactive factors such as insulin-like growth factor (IGF-I), IGF-II, growth hormone (GH), insulin, prolactin (PRL) and leptin can influence post-natal intestinal development.4 She found that researchers reported that the non-nutrient factors in colostrum modulate the gastrointestinal tract (GIT) including cell proliferation, digestion, and immune system development and function, as well as functions outside of the GIT.5
Dr Yunta also notes that there is a growing body of evidence that shows that colostrum has significant impact on the glucose status of calves. Colostrum intake, it seems, enhances glucose absorption by increasing intestinal surface6 and improving lactose digestion. And, calves that were fed sufficient volumes of high quality colostrum had greater insulin concentrations after meals than calves that did not receive colostrum,7 providing more evidence of colostrum's effect on intermediary metabolism.
Effects of upping milk quantity fed pre-weaning on growth and performance
Dr Yunta found that calves fed the traditional pre-weaning diet that restricts milk allowances had both low growth rates8 and high mortality rates.9 On the other hand, she points to numerous recent studies which show greater growth rates achieved through upping the level of milk fed and at increased rates.10 Additionally, Dr Yunta points out that while in the past it was thought that increasing the amount of milk fed would increase the risk of scours, that notion has recently been contraindicated in several studies,11 given proper management techniques, coupled with a quality, well-formulated calf milk replacer.
She also examined the body of research that points to the link between higher eventual milk yield and higher plane of early life nutrition. She found that calves that were fed large amounts of whole milk had a greater milk yield during their first lactation than restricted calves.12 Additionally, Dr Yunta points to other studies which show that increased nutrient intake (which leads to higher ADGs) during the crucial first weeks of life leads to greater milk yield during the first lactation.13 She does note that this may be due to increased calving body weight of those fed a higher plane of nutrition pre-weaning, as there is a strong correlation between the two. Indeed, increasing the plane of nutrition pre-weaning brings about higher ADGs, which research has shown, in combination with proper management during and after weaning, leads to sustained higher body weights long after transitioning to solid feed.
Ensuring that the proper amount of high quality colostrum is fed to calves just after birth is essential in order for calves to reap the benefits of both IgG's and other vital colostral factors that positively affect calf health and metabolism. Additionally, raising the plane of pre-weaning nutrition aids in both short- and long-term calf growth and future lactation performance.