Tissues, Metabolic Pathways and Genes of Key Importance in Lactating Dairy Cattle

Shadi Nayeri,Paul Stothard

doi:10.1007/s40362-016-0040-3

Abstract

Milk and dairy products are valuable sources of food for humans. Increased milk yield and changes in milk composition in dairy cows have been achieved through a variety of means including better nutrition, management and genetic selection. This selection can be performed without consideration of the specific genes and genetic variation involved. However, association analysis using dense SNP genotyping panels provides an approach for identifying genomic regions affecting milk production. Coupling physiological and metabolic information with association analysis results can provide greater insight into the specific genetic variants and molecular mechanisms affecting production traits as well as the potential effects of these variants on fertility in dairy cattle. To this end, this review highlights key tissues, metabolic pathways and genes of importance in lactating dairy cattle, particularly early in lactation. Physiological and metabolic adaptations in three key tissues (adipose, mammary gland and liver) are discussed, followed by the important endocrine adaptations during negative energy balance. Key genes mediating metabolic and endocrine adaptations are also highlighted. Finally, genes that account for variation in production traits are presented in relation to the tissues and processes described. Knowledge of the genes and pathways involved will be important for ongoing efforts aimed at finding other genes and variants that contribute to milk production and fertility traits. Also, a better understanding of the molecular basis of these traits may lead to more accurate genomic predictions.

Highlights

Humans have recognized milk and dairy products as a valuable source of sustenance since as early as 4000 BC [8, 95]
Ongoing genetic selection as well as advances in the understanding of the biology of lactation and biosynthesis of milk such as improved understanding of the interrelations between dietary components, digestive processes in the rumen and the regulation of mammary synthesis of milk fat have led to improve in management and substantial increases in milk production and productivity [8, 53]
The key genes that are involved in regulating energy metabolism in multiple tissues include PPRA, PCK1, PCK, ACACA, FASN, FBP2, FABP3, PPARGC1A, ACSL1, PPARGC1A, AGPAT6, PCCA, LPIN1, ACO, carnitine palmitoyltransferase (CPT)-I, Carnitine palmitoyltransferase II (CPT-II) and ACSL [4, 15, 27, 94, 131, 163]

Summary

Introduction

Humans have recognized milk and dairy products as a valuable source of sustenance since as early as 4000 BC [8, 95]. The key genes that are involved in regulating energy metabolism in multiple tissues include PPRA, PCK1, PCK, ACACA, FASN, FBP2, FABP3, PPARGC1A, ACSL1, PPARGC1A, AGPAT6, PCCA, LPIN1, ACO, CPT-I, CPT-II and ACSL [4, 15, 27, 94, 131, 163] These genes are involved in fatty acid uptake (mainly in the liver and mammary gland), mitochondrial and peroxisomal fatty acid oxidation, ketone body metabolism (ketogenesis) and cholesterol metabolism (in liver) early in lactation in dairy cattle [135] and are discussed in the following tissue-specific sections in more detail. The authors suggest that application of whole-genome sequence data in GWAS analysis along with gene network and pathway information may help to better identify candidate genes and variations affecting multiple production and fertility traits and indicates possible pathways that correlate these traits

Conclusion

Findings

Motivation