Effect of feed additive supplementation on rumen bacterial amino acid profile and fermentation dynamics in dairy cows

Four late-lactation Holstein-Friesian cows were utilised in a 4 x 4 Latin square design experiment to evaluate the effect of a calcareous marine algae buffer, Acid Buf 10 (Celtic Sea Minerals), a direct-fed microbial product, AchieveFE (MicroBasics Inc.) and sodium monensin (Rumensin, Elanco Animal Health) on ruminal fermentation patterns, microbial crude protein (MCP) production, and the amino acid (AA) profile of the ruminal bacteria associated with the liquid and solid phases. The basal diet fed was a total mixed ration (TMR) comprised of 400 g/kg high quality Lucerne hay and 600 g/kg concentrates, of which 399 g/ kg of concentrate was ground corn (dry matter (DM) basis). Treatments were: (1) control diet (C), (2) control diet plus 3.75 g/kg DM of Acid Buf 10 (AB10), to achieve an intake of 90 g/cow/day, (3) control diet plus 10 g/day of AchieveFE (DFM) inserted directly into the rumen, and (4) control diet plus 10.84 mg/kg DM of monensin (MON), to achieve an intake of 260 mg/cow/day. The four experimental periods consisted of a 14 day “wash-out” period and an 11 day collection period. Cows were fed their respective TMR ad libitum twice daily at 08:00 and 14:00, with the DFM product being placed directly into the rumen daily prior to the 08:00 feeding. Cows were milked three times daily at 06:00, 12:00 and 19:00.Dissertation (MSc (Agric))--University of Pretoria, 2019.Animal and Wildlife SciencesMSc (Agric)Unrestricte