Forage preservation (grazing vs. hay) fed to ewes affects the fatty acid profile of milk and CPT1B gene expression in the sheep mammary gland

In this study, the forage type affected the C18:2 cis-9 trans-11 (CLA) and long-chain saturated fatty acid (LCFA) content, with higher percentages during grazing than during hay feeding. This may suggest that these FAs act as regulatory factors for the transcriptional control of the carnitine palmitoyltransferase 1B (CPT1B) gene, which was more highly expressed in the grazing group (GRE). The most highly expressed gene in the mammary gland at the fifth week of lactation is CAAT/ enhancer- binding protein beta (CEBPB), possibly due to its role in milk fat synthesis in the mammary gland. More stable housekeeping genes in the ovine mammary gland that would be appropriate for use in gene expression studies were ribosomal protein L19 (RPL19) and glyceraldehyde- 3- phosphate dehydrogenase (GAPDH).Small changes in diet, such as the forage preservation (grazing vs. hay), can affect the milk fatty acid profile and the expression of the CPT1B gene, which is associated with the oxidation of fatty acids. When compared to hay fed indoors, grazing fresh low mountain pastures stimulates the milk content of CLA and LCFA via mammary uptake. In this sense, LCFA in milk may be acting as a regulatory factor for transcriptional control of the CPT1B gene, which was more highly expressed in the grazing group.Sheep milk fat is rich in medium-chain triglycerides (MCT), which are composed of fatty acids with a carbon chain of 6–10 carbon atoms. MCTs are of special therapeutic interest because of their specific metabolism and their consequent application in certain types of metabolic illnesses [1]. By contrast, medium-chain saturated fatty acids, mainly C12:0 and C14:0, are considered to have a negative effect on human health when consumed in excess [2]. Other fatty acids (FAs), such as oleic (C18:1 n-9), linolenic (C18:3 n-3), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and conjugated linoleic acid (CLA, C18:2 cis-9 trans-11), have positive effects on human health [3,4]. Milk fat