The associative effects of Chlorella vulgaris microalgae and copper (Cu) supplementation on feed utilisation and lactational performance in goats were evaluated. Thirty-two lactating Boer goats (34.8 ± 1.7 kg body weight) were used to evaluate the supplementation of C. vulgaris microalgae at 10 g/day (AL treatment), 9 mg of Cu/kg diet (CU treatment) or a mixture of both AL and CU treatments (ALCU treatment) on feed intake, nutrient digestibility, ruminal fermentation, blood metabolites and lactation performance of Boer goat milk yield and composition. Treatments did not affect feed intake; however, AL, ALCU and CU treatments increased (p < .001) nutrient digestibility. Treatment effect on ruminal pH, ammonia-N or propionate was marginal, but AL and ALCU treatments increased (p < .01) acetate, acetate/propionate ratio and total volatile fatty acids. Treatments increased (p < .001) serum glucose and Cu concentrations. Additionally, ALCU and AL treatments increased (p < .001) daily milk yield, energy corrected milk production, concentrations of ash, energy content, fat, lactose, solids not fat, total solids and milk (feed) efficiency. Conversely, the CU treatment decreased (p < .001) the concentration of all milk components, without affecting milk (feed) efficiency. Additionally, AL and ALCU treatments decreased (p < .05) the concentrations of saturated fatty acids by 2.4% and 4%, respectively, but increased (p < .05) the concentrations of total unsaturated fatty acids (UFAs) by 5.4% and 9.8%, respectively, mono-UFA by 5.2% and 9.8%, respectively, and conjugated linoleic acid concentrations by 9.3% and 7.4% respectively. In conclusion, supplementation of the diet of lactating Boer goats with C. vulgaris microalgae with or without copper enhanced nutrient digestibility, ruminal fermentation, milk production, milk efficiency and milk nutritive value. Copper supplementation had minimal effects; therefore, its use as a supplement in the presence of C. vulgaris microalgae to the diet of lactating Boer goats is recommended.
Keywords: copper; microalgae; milk yield; mineral feeding; nutrient utilisation.
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