Performance and milk composition of nubian goats as affected by increasing level of Nannochloropsis oculata microalgae

Abstract

Fat supplementation affects the lactational performance of goats and dramatically changes milk nutritive value. In the present experiment, two levels of Nannochloropsis oculata microalgae, a natural source of rumen-protected eicosapentaenoic acid (EPA), were studied in the diet of Nubian goats. Using quintuplicated 3 × 3 Latin square design, fifteen lactating goats, (14 ± 2 months old and 33.0 ± 1.3 kg) after kidding, were randomly assigned into three treatments in an 84-d assay. Goats were offered a basal diet comprising berseem clover, wheat straw and concentrates in 3:2:5, respectively, (control treatment-no supplementation). The other two treatments were supplemented with N. oculata microalgae at 5 g (NOM5 treatment) or 10 g (NOM10 treatment)/doe/d. Without affecting intake, treatments improved (p < 0.01) nutrient digestibility. Supplementations had no effect on ruminal pH and ammonia-nitrogen, however, NOM5 and NOM10 linearly improved (p < 0.05) total volatile fatty acids and propionic acids. N. oculata supplementation linearly increased (p < 0.01) milk yield and lactose content. Supplementation reduced atherogenic index (p = 0.004) and enhanced the concentrations of unsaturated fatty acids and C20:5n3 (EPA). Conclusively, feeding Nubian goats on diet supplemented with N. oculata at 5 and 10 g improved milk production and the nutritive value. No improvements in the performance were observed when N. oculata dose was increased from 5 g to 10 g/doe; thus, 5 g dose is recommended for use.