The effect of long‐term under‐ and overfeeding on the expression of six major milk proteins' genes in the mammary tissue of goats

Abstract

Milk protein synthesis in the mammary gland involves expression of six major milk proteins' genes whose nutritional regulation remains poorly defined. In this study, the effect of long-term under- and overfeeding on the expression of as1-casein: CSN1S1, as2-casein: CSN1S2, β-casein: CSN2, κ-casein: CSN3, α-lactalbumin: LALBA and β-lactoglobulin: BLG gene in goat mammary tissue (MT) was examined. Twenty-four lactating dairy goat, at 90-98 days in milk, were divided into three homogenous subgroups and fed the same ration, for 60 days, in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant decrease in mRNA of CSN1S2, CSN2, CSN3 and LALBA genes in the MT of underfed goats compared with the overfed and on the CSN1S1 and BLG gene expressions in the MT of underfed goats compared with the respective control and overfed. CSN2 was the most abundant transcript in goat MT relative to the other milk proteins' genes. Significantly positive correlations were observed between the mRNA levels of caseins' and BLG genes with the milk yield. Moreover, a significant correlation was found between the mRNA levels of CSN1S2 with the milk protein, lactose content and lactose yield and also between the LALBA gene expression with the lactose content and lactose yield respectively. In conclusion, the feeding level and consequently the nutrients availability affected the milk lactose content, protein and lactose yield as well as the milk volume by altering the CSN1S1, CSN1S2, CSN2, CSN3, LALBA and BLG gene expression involved in their metabolic pathways.

Polymorphism at the CSN1S1 Locus and Energy Intake Level Affect Milk Traits and Casein Profiles in Rossa Mediterranea Goats

“…Ollier et al [ 29 ], by studying the impact of 48 h food deprivation on goat mammary gene expression, found a downregulation for αs 1 and αs 2 precursors. Tsiplakou et al [ 30 ], who investigated the impact of long-term underfeeding and overfeeding on the expression of six major milk protein genes (αs 1 -casein, αs 2 -casein, β-casein, κ-casein, α-lactalbumin and β-lactoglobulin) in the mammary goat tissue, observed that underfeeding led to a decrease in the expression level of all genes, suggesting that our experimental L diet could negatively impact milk protein synthesis.…”

Effect of hyperthermia on cell viability, amino acid transfer, and milk protein synthesis in bovine mammary epithelial cells

“…As the MAC-T cell line is incapable of secreting milk components, milk protein content could not be detected directly in this study. The CSN2 gene expression is positively associated with milk yield [ 47 ]. Hence, the expression of casein genes may be used to evaluate milk yield as an alternative to the evaluation of casein protein synthesis in MAC-T cells [ 48 ].…”

Gene expression pattern of acetyl-coA carboxylase alpha, fatty acid synthase, and stearoyl-CoA desaturase in pregnant Barki sheep under complete feed deprivation

“…Feeding level and nutrient availability, may affect glucose uptake and utilization in sheep [26] The effect of long term underand over-feeding on the expression of genes related to lipid metabolism [26] and major milk proteins' genes [27] in the mammary tissue of small ruminants have been described. However, little information on the effect of complete feed deprivation on gene expression of genes related to lipid metabolism in pregnant sheep is not available.…”