The effect of long term under- and over-feeding on the expression of genes related to lipid metabolism in the mammary tissue of goats

• Negative energy balance down regulates the lipogenic genes expression.
• FAS is the most abundant transcript in goat mammary gland.
• The lactation stage affects the SCD1 expression.
• The expression of ACACA and FASN in goats MT followed the same pattern with the SCFA and MCFA yields in their milk.

Fat synthesis is under the control of a large number of genes whose nutritional regulation is still poorly documented. In this study, we examined the effect of long term under- and over-feeding on the expression of genes (acetyl-CoA carboxylase: ACACA, fatty acid synthetase: FASN, lipoprotein lipase: LPL, stearoyl-Co A desaturase 1: SCD1, peroxisome proliferator activated receptor G2: PPARG2, sterol regulatory element binding protein-1c: SREBP-1c and hormone sensitive lipase HSL) related to FA metabolism in goat mammary tissue (MT). Twenty four lactating goats were divided into three homogenous sub-groups and fed the same ratio in quantities covering 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant reduction on mRNA of ACACA, FASN, LPL, SCD1 and HSL in the MT of underfed goats, compared with the respective overfed. A numerical decrease on the mRNA level of PPARG2 and SREBP-1c in the MT of the underfed goats, compared with the respective controls and the overfed was also observed. In conclusion, the negative, compared to positive, energy balance in goats down regulates the ACACA, FASN, LPL, SCD1 and HSL expressions in their MT which indicates that the decrease in nutrient availability may lead to lower rates of lipid synthesis.