Enhancing milk quality and modulating plasma lipid metabolism of lactating dairy goats: The impact of bile acid supplementation.

An essential function carried out by bile acids (BA) is to aid in lipid absorption, as they emulsify lipids and combine with them to form chylomicrons. While BA have been utilized as lipid emulsifiers in monogastric and aquatic animals, their impact on ruminants remains relatively unexplored. Two experiments were conducted to investigate the effects of BA on the lipid absorption of lactating dairy goats. In the Exp. 1, twelve lactating goats with similar days in milk (42 ± 2 d), body weight (46.2 ± 5.1 kg), and milk yield (1.62 ± 0.33 kg) were administered four BA doses (0, 1, 2, or 4 g/d) to explore the effects of BA supplementation. The results observed a positive correlation between the BA dose and plasma total bile acid concentration (P < 0.001). Notably, when goats received BA, there was a trend of increase in the proportion of preformed fatty acids in milk (P = 0.079). In the Exp. 2, eighteen lactating goats with similar days in milk (100 ± 6 d), body weight (45.0 ± 3.7 kg), and milk yield (1.60 ± 0.31 kg) were divided into two groups (HF and HFB): HF group received no BA, while HFB group received BA (4 g/d). Both the groups were fed diets with fat powder supplementation (1% of dry matter) for 5 weeks. BA supplementation led to a significant increase in milk yield (P = 0.024) and fat concentration (P = 0.045). Meanwhile, there was a significant rise of total bile acid concentration in plasma (P < 0.001), rumen (P < 0.001) and feces (P < 0.001). Additionally, BA supplementation had a significant impact on blood metabolism, up-regulating 241 metabolites and down-regulating 208 metabolites (P < 0.05). BA supplementation also altered the correlations among various plasma lipid components (P < 0.05). In fatty acid (FA) analysis, 26 different FA were detected, out of which 16 showed significant down-regulation upon BA supplementation (P < 0.05). In conclusion, BA supplementation positively influenced lactating dairy goats, particularly when fed diets with fat powder supplementation. BA supplementation enhanced milk yield, improved milk fat concentration, and significantly altered lipid-related blood metabolism. These findings suggest that BA supplementation could be a valuable strategy for enhancing dairy production and lipid metabolism in dairy goats, offering potential benefits for the dairy industry.