Rumen-protected choline supplementation in periparturient dairy goats : effects on liver and mammary gland

We investigated the effects of supplementing rumen-protected choline on metabolic profile, selected liver constituents, and transcript levels of selected enzymes, transcription factors, and nuclear receptors, involved in mammary lipid metabolism in dairy goats. We studied 8 healthy lactating goats, four received no choline supplementation (CTR group) and 4 received 4 g/day rumen-protected choline chloride (RPC group). The treatment was administered individually starting 4 weeks before expected kidding and continuing for 4 weeks after parturition. In the first month of lactation, milk yield and composition were measured weekly. On days 7, 14, 21 and 27 in milk, blood samples were collected and analysed for glucose, -hydroxybutyrate, non-esterified fatty acids, and cholesterol. On day 28 in milk, samples of liver and mammary gland tissue were obtained. Liver was analyzed for total lipid and DNA content; mammary tissue was analyzed for transcripts of lipoprotein lipase (LPL), fatty acid synthase, sterol regulatory binding proteins 1 and 2, peroxisome proliferator-activated receptor  and liver X receptor α. Milk yield was closely similar in the two groups, but RPC goats had lower (P<0.05) plasma -hydroxybutyrate. The total lipid content of liver was unaffected (P=0.89) but the total lipid/DNA ratio lower (both P<0.05) in RPC than CTR animals. Choline had no effect on the expression of the mammary gland transcripts involved in lipid metabolism. Our plasma and liver data indicate that choline has a positive effect on liver lipid metabolism, whereas it appears to have little effect on transcript levels in mammary gland of various proteins involved in lipid metabolism. Nevertheless, our results were obtained from a limited number of animals, and choline requirement and function in lactating dairy ruminants deserve further investigation.