Nutrigenomics in dairy cows
Nutrigenomics is defined as the study of the genome-wide influences of nutrition altering the expression and/or structure of an individual’s genetic makeup. Nutrigenomics can be performed in a reductionist way, with the intent to dissect the nutritional effect on a limited part of the genome (e.g., expression of few genes) or using a systems biology approach, where a holistic view of the nutritional effect on the genome is studied. Nutrigenomics in dairy cows is a relatively new area of research. Among all nutritional factors able to affect cell biology by changing gene expression, dietary energy, fatty acids, and amino acids have the strongest potential. The level of dietary energy has a powerful and broad transcriptomics effect. This was evidenced by data generated in liver and adipose tissue, especially in peripartal dairy cows. Profound nutrigenomics effects of amino acids are emerging, particularly during the process of milk protein synthesis. The most powerful nutrigenomics dietary components are fatty acids, particularly long-chain fatty acids (LCFA). In relation to dairy production, the effect of trans10,cis12-conjugated linoleic acid on depressing milk fat synthesis via effects on few well-studied enzymes was among the first and likely the best-known nutrigenomics example tied to LCFA. The LCFA can affect expression of genes primarily because of their capacity to modulate activity of specific transcriptional factors. Among those the most-sensitive to LCFA and best-studied are the peroxisome proliferator-activated receptors (PPARs). Emerging data support a role of PPARs in ruminant physiology and metabolism, including the regulation of milk fat synthesis. In addition, at least in vitro, there is a strong agonistic effect of LCFA, particularly the saturated fatty acids, in activating PPARs in ruminants. The capacity of LCFA to modulate PPARs (and likely other transcriptional factors such as LXR) offers the possibility to fine-tune the biology of dairy animals, including milk synthesis. The emerging data on PPARs in ruminants allowed proposing a dynamic model where activation of PPARs in several major tissues at distinct physiological stages could improve the adaptation of dairy cows to lactation. We are at the frontier of the nutrigenomics era in ruminants and initial data strongly indicate that this scientific branch can play a critical role in future strategies to feed dairy cattle. Outputs from nutrigenomics research can help improve efficiency of high-producing dairy cows and modifying milk quality for an ever growing number of consumers demanding “healthy” food.
Keywords: Nutrigenomics; Dairy Cow; Transcription Factors