Effect of Feeding Green Microalgae and Bacillus subtilis on Growth Performance, Blood Metabolites and Nutrient Digestibility of Beef Bulls in Arid Subtropics

Abstract

Background: Green microalgae and Bacillus subtilis have been known to promote productive and reproductive performances in ruminant species. The present study aimed to improve productive performance, nutrient digestibility and serum metabolites upon supplementation Bacillus subtilis and green microalgae under heat stress conditions. Methods: Eighty crossbreed beef bulls were allocated into four groups of 20 bulls each. The first group served as control, the second group was supplemented with 13 g/head/day of Bacillus subtilis, the third group was supplemented with 30 g/head/day of Dunaliella salina and the fourth group was supplemented with both B. subtilis and D. salina. Daily weight gain and total weight gain were estimated. Blood samples were collected at every four weeks of experimental period and metabolic profiles were measured. Result: Digestibility coefficients were improved in all treated groups compared to control. Body weight gains and feed efficiencies recorded higher value in Bacillus subtilis and microalgae group. The serum total protein were higher in green microalgae compared to other groups during weeks 8 and 12. Moreover, blood urea nitrogen was higher in all treatment groups compared to control at week 12. Microalgae and combination of both microalgae and Bacillus subtilis increased hemoglobin, red and white blood cells.