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trans-10,cis-12-Conjugated Linoleic Acid Affects Expression of Lipogenic Genes in Mammary Glands of Lactating Dairy Goats
- Shi, Huaiping, Zhang, Tianying, Li, Cong, Wang, Jianjue, Huang, Jiangtao, Li, Zhongyang
- Journal of agricultural and food chemistry 2017 v.65 no.43 pp. 9460-9467
- Saanen, animal tissues, conjugated linoleic acid, dairy goats, diet, gene expression, genes, lactating females, lactation stage, lipogenesis, mammary glands, medium chain fatty acids, messenger RNA, milk, milk fat, milk fat yield, quantitative polymerase chain reaction, reverse transcriptase polymerase chain reaction
- The molecular mechanisms on milk fat depression (MFD) in response to trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) supplementation in ruminants were elucidated in this research with dairy goats. A total of 30 2-year-old Xinong Saanen dairy goats [40 ± 5 days in milk (DIM)] at peak lactation stage were assigned to a 3 × 3 Latin square design (14 day treatment period, followed with 14 day washout). Three CLA treatments included (a) control, fed the basal diet only without CLA supplementation; (b) orally supplemented with 8 g/day of lipid-encapsulated CLA (low dose, CLA-1); and (c) orally supplemented with 16 g/day of lipid-encapsulated CLA (high dose, CLA-2). Expression levels of fatty acid metabolism genes in the mammary tissues were analyzed by real-time quantitative polymerase chain reaction (RT-qPCR) in three goats on day 1 and the other three goats on day 14 in each group after the discontinuation of CLA treatment in the third experimental period. Dietary supplementation of CLA led to a significant decrease of milk fat compared to the control (p < 0.05). Milk fat concentrations in CLA-1 and CLA-2 groups were 2.74 and 2.42%, respectively, while the milk fat concentration in the control group was 2.99%. Decreases in short- and medium-chain fatty acids (<16 carbons) and increases in unsaturated fatty acids were observed in the CLA-2 group (p < 0.05). The desaturation indexes of C16 and C18 fatty acids were obviously increased (p < 0.01). RT-qPCR results revealed decreases of the mRNA expression levels of SREBF1, PPARG, LPL, CD36, FABP3, ACSL1, FASN, ACACA, DGAT2, TIP47, ADRP, and BTN1A1 genes in mammary glands (p < 0.05) and an increase of the SCD gene because of CLA supplementation (p < 0.05). In conclusion, t10,c12-CLA-induced MFD was possibly the result from the downregulation of genes involved in lipogenesis in goat mammary glands.