Associate professor Márcio Ladeira
Universidade Federal de Lavras
Márcio Ladeira graduated with a Master’s in Animal Science from the Federal University of Viçosa and a PhD in Animal Science from the Federal University of Minas Gerais, both in Brazil. He also completed a sabbatical study on fetal programming at Purdue University, Indiana, USA. His career experience in Animal Science included focuses on the following key subjects: beef cattle nutrition, feedlot, carcass and meat quality, nutrigenomics and lipids.
In addition to his role as an associate professor at the Federal University of Lavras where he coordinates the Animal Science Graduate Programme, Ladeira is an animal science researcher for Brazil’s National Institute of Science and Technology. He is currently conducting research into fetal programming in Brazilian Nellore cows, how feedlot diets can change the expression of genes involved in lipogenesis, and post ruminal starch digestion.
Fetal programming in beef cattle
Professor Márcio Ladeira of the Federal University of Lavras, Brazil, was the first speaker on the second day of the international symposium that marked the opening of Trouw Nutrition's new Calf & Beef Research Facility in April, 2016.
His talk focused on fetal programming in beef cattle and included a valuable explanation of what fetal programming is and what is already know about it, as well as a thorough discussion of recent experimental results in Brazil. He gave particular emphasis to the role fetal programming can have in tropical countries, where the often dry winter climate makes it difficult for cows to get the required nutrition while gestating.
What is fetal programming?
Professor Ladeira began his talk by explaining that fetal programming is the understanding that the nutrition level of mothers (as well as environmental conditions and diet composition) while they are pregnant facilitates changes in the tissue formation of fetuses during gestation. These changes have long-term effects on the way certain genes are expressed after the birth of the offspring. While he noted that the science behind fetal programming began and flourished with human studies, a variety of scientific experiments have shown that the basics can also be understood in terms of bovine production systems. As Professor Ladeira's own research takes place in a tropical climate where the dry winter months prove difficult for pregnant heifers and cows to have adequate nutritional inputs, his emphasis is on potential undernourishment of pregnant heifers, and the problems that could lead to in measurable long-term performance goals of their offspring.
What do we already know about fetal programming in beef cattle?
After a thorough explanation of mesenchymal cells and how they get converted into muscle fibres, adipocytes or fibroblasts with the utilization of protein and transcription factors including MRFs and WNT, Professor Ladeira put forth the very important notion that all bovine muscle fibre cells are formed during gestation and that it is not possible to produce more muscle fibre after birth. Therefore, according to research he described by Dr Ming Du which covered tissue formation by trimester in gestation, depending on how you feed your cows, you can indeed change the tissue formation of the fetus and, ultimately, of the potential production of the calf.
Professor Ladeira pointed to several other examples of research that emphasized this basic point, including a mid-gestation sheep study (Quigley et al., 2005) which showed muscle fibres were compromised in fetuses of ewes with low feed intake, and a study of the 8 month-old offspring of nutrient restricted sheep (Zhu et al., 2006) showing that nutrient restriction negatively affects skeletal muscle development with long-term consequences. He also discussed several bovine experiments, including work from Underwood et al. (2010) and Greenwood et al. (2010) showing weaning weight and average daily gain results to be much lower in calves whose dams were restricted during gestation.
The need for fetal programming in beef cattle in Brazil
Switching his focus, Professor Ladeira reiterated why studying fetal programming is so important in Brazil: During the dry, winter months, there is low forage availability and what is available is of poor quality. Because of this, cows have poor nutrition during mid-gestation and, therefore, their offspring aren't performing as well as they could.
To underscore this, he shared his insights on a ground breaking Brazilian study by Gionbelli et al. (2015) in which 44 pregnant cows were separated into two nutritional groups (low fed vs. high fed). Researchers slaughtered the fetuses between 140 days and 270 days of gestation. The timing of slaughter gave the researchers deeper insights into the different phases of myogenesis and adipogenesis. What they found was while the nutritional plan of the mothers did not change the fetal size, it did change the way muscle tissue developed. Interestingly, they found that in the 140 day fetuses whose dams had higher nutritional inputs during gestation, β-Catenin was more expressed.
This, in combination with transcription factor WNT means more myogenesis which results in more muscle tissue. Additionally, higher nutritional inputs were found to influence the expression of the adipogenesis gene. Thus, Gionbelli et al. found that both myogenesis and adipogenesis were compromised when cows had lower nutrition during pregnancy.
Professor Ladeira continued his presentation by focusing on current and ongoing research at the Federal University of Lavras which focuses on 92 pregnant cows and the male fetuses they carried during the dry season that have since been born. While pregnant, the cows were separated into two groups and were given either supplemented nutrition (pasture plus 1 kg per day of 40% crude protein) or a control nutritional input of pasture feeding plus mineral salt. The supplemented cows had greater body weight gain than the control group, and the calves of the supplemented cows weighed almost 2kg more at birth than the calves of the control group.
However, 120 days after birth no significant difference in weight was observed. Professor Ladeira noted that they did not see any real differences between groups in the calves they slaughtered at birth, but he posited that perhaps they will see differences in the remaining calves' eventual performance.
While Professor Ladeira does feel that more needs to be invested in and studied on the subject, he believes that fetal programming will most likely continue to be an important tool in beef cattle production systems, especially in extensive, tropical systems like Brazil, where it's difficult to ensure that gestating cows get the required nutrition.