The effect of dietary C hlorella vulgaris supplementation on micro‐organism community, enzyme activities and fatty acid profile in the rumen liquid of goats

Microalgae might be considered as an alternative source of fat and/or protein for ruminant's diets. However, changes in populations of ruminal micro‐organisms associated with biohydrogenation process, methane and ammonia production in response to microalgae dietary supplementation have not been well characterized. Thus, 16 cross‐bred goats were divided into two groups. Each goat of both groups was fed individually with alfalfa hay and concentrates separately. The concentrates of the control group had no microalgae while those of the treated group were supplemented with 10 g lyophilized C hlorella vulgaris/ kg concentrate (chlor). On the 30th experimental day, samples of rumen fluid were collected for microbial DNA extraction, fatty acid profile and enzyme activity analyses. The results showed that the chlor diet compared with the control increased significantly the populations of M ethanosphaera stadtmanae , M ethanobrevibacter ruminantium and M ethanogens bacteria and protozoa in the rumen of goats. A significant reduction in the cellulase activity and in the abundance of R uminococcus albus, and a significant increase in the protease activity and in the abundance of C lostridium sticklandii in the rumen liquid of goats fed with the chlor diet, compared with the control, were found. C hlorella vulgaris supplementation promoted the formation of trans C 18:1 , trans‐11 C 18:1 and monounsaturated fatty acids ( MUFA ), while the proportions of C 18:0 and long‐chain fatty acids ( LCFA ) reduced significantly in the rumen liquid of goats. This shift in ruminal biohydrogenation pathway was accompanied by a significant increase in B utyrivibrio fibrisolvens trans C 18:1 ‐producing bacteria. In conclusion, the supplementation of diets with microalgae needs further investigation because it enhances the populations of methane‐producing bacteria and protozoa.