Muscular fat or marbling is an important sensory quality of pork that influences consumer preference and premiums for pork. As a result, improving the quality of pork marbling is of great importance to pig nutritionists, breeders and geneticists for both health and economic reasons.
Many factors, such as the genetic makeup of the pig, sex, age, dietary micronutrients and environmental conditions, influence lipid metabolism and phenotypic response in pigs. In addition, recent studies have found that lipid and marble metabolism is regulated by several genes that are directly or indirectly involved in fatty acid metabolism and cell proliferation and differentiation. Nutritional genetics and nutritional genetics are two different scientific fields that provide a general approach to understanding the complex mechanisms of interaction between genetic nutrients and the environment over the entire genome.
Nutritional genetics vs. nutritional genetics
Nutritional genetics and nutrigenomics are two distinct terms that are often confused; Therefore, it is necessary to clearly distinguish between them. The term “nutrient” (or nutrient) refers to chemical compounds in the diet that are required for cellular functions. Genetics is the study of individual genes, while genomics is the study of the entire genome that represents the totality of an organism’s genes and their interactions and how they are affected by the environment.
Nutritional genetics studies the influence of individual genetic-level differences in response to a particular dietary pattern, functional food, or supplement on a specific health outcome; While nutritional genetics assesses the effect of nutrient intake on gene expression and subsequent related molecular and biological events.
Effect of genetic makeup on response to nutrient intake
Most of the genes related to fat metabolism indirectly affect the muscle fat content of pork. However, their effects have shown variability with regard to muscle location and mechanisms of fat synthesis. Intramuscular fat content and meat quality traits differ between pig breeds due to different expressions of genes and enzymes involved in fatty acid synthesis and fat metabolism. Various studies have reported that the following genes are related to lipid metabolism and intramuscular fat content in pig breeds.
especially PPARα and PPARγ that is associated with metabolic pathways related to lipid metabolism. higher concentrations of PPARα is mainly found in organs such as the liver, while PPARγ It is more concentrated in adipose tissue.
In the first class A-FABP And the H-FABP which are involved in lipid metabolism and transport intracellular fatty acids from the cell membrane to the sites of fatty acid oxidation.
SCD It is a functional gene associated with the fatty acid synthesis of pigs and serves as an important regulator of the genetic machinery of lipid deposition and fatty acid synthesis.
Porcine leptin is involved in feed intake and energy homeostasis and influences the rate of intramuscular fat accumulation.
Akaka And the fascinate genes
Both of these genes regulate fatty acid synthesis and their expression level varies between strains of pigs.
MSTN or GDF8 gene
This gene is responsible for the double muscle in domestic Belgian pig breeds.
This gene has a critical role in the gene transcription machinery and the regulation of muscle fat deposition.
Effect of dietary nutrient supply on gene expression
Protein, amino acids, fats and micro/macro supplements are applied during the different growth and development stages of pigs. Dietary protein levels have a regulatory mechanism of gene expression related to lipid metabolism. A higher dietary protein supply of 18% significantly reduced mRNA expression, enzyme activity, and expression levels of adipose and marbling genes in pigs.
Changing dietary lysine level can have a significant effect on dietary genes in pigs
In addition, amino acids such as methionine, lysine, histidine, isoleucine, leucine, phenylalanine, threonine, tryptophan, and valine are essential in many metabolic pathways and gene expression. Changing the dietary lysine level can have a significant effect on dietary genes in pigs. Decreased amount of lysine in the diet of heavy finishing pigs promotes better muscle fat deposition and marbling formation. Studies have shown that supplementing with 0.78% lysine results in higher muscle content in raising pigs.
Micronutrients influence the expression pattern of many genes and modulate gene signaling pathways and their regulatory elements during growth and development. In addition, dietary fatty acids have a bio-regulatory effect on DNA receptors and enzymes during DNA transcription and translation.
The scientific fields of nutritional genetics and nutritional genetics are effective and accurate in describing the changes in gene sequences that predispose individual pig breeds to respond in a particular way in terms of health, performance, and meat quality. Based on the principles of alimentary genetics and alimentary genetics, the complex mechanisms of interaction between genetic nutrients and environmental influence on the entire genome can be explained. This makes it possible to measure dietary effects with the aim of tuning gene expressions and regulating genomic responses in pigs, to improve growth performance, rebound fat thickness, muscle deposition, disease resistance and meat quality characteristics. However, given the wide diversity of pig genes, environment, and the quality and quantity of nutrients in any diet, determining the individual effect of all nutrients on genetic responses remains challenging. This means that more research is needed to be able to incorporate the scientific principles of nutritional genetics and nutritional genetics as a tool in pig nutrition and feeding.