Post-ruminal branched-chain amino acid supplementation and intravenous lipopolysaccharide infusion alter blood metabolites, rumen fermentation, and nitrogen balance of beef steers1. (27th April 2018)

• Record Type: Journal Article
• Authors: Löest, Clint A; Gilliam, Garrett G; Waggoner, Justin W; Turner, Jason L
• Is Part Of: Journal of animal science. Volume 96:Number 7(2018)
• Page Start: 2886
• Page End: 2906
• Publication Date: 2018-04-27
• Subjects: branched-chain amino acids -- endotoxin -- steers; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/sky168
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: Steers exposed to an endotoxin may require additional branched-chain AA (BCAA ) to support an increase in synthesis of immune proteins. This study evaluated effects of bacterial lipopolysaccharide (LPS ) and BCAA supplementation on blood metabolites and N balance of 20 ruminally-cannulated steers (177 ± 4.2 kg BW). The experiment was a randomized block design, with 14-d adaptation to metabolism stalls and diet (DM fed = 1.5% BW) and 6-d collection. Treatments were a 2 × 2 factorial of LPS (0 vs. 1.0 to 1.5 μg/kg BW; −LPS vs. +LPS ) and BCAA (0 vs. 35 g/d; −BCAA vs. +BCAA ). The LPS in 100 mL sterile saline was infused (1 mL/min via i.v. catheter) on day 15. The BCAA in an essential AA solution were abomasally infused (900 mL/d) three times daily in equal portions beginning on day 7. Blood, rumen fluid, and rectal temperature were collected on day 15 at h 0, 2, 4, 8, 12, and 24 after LPS infusion. Feces and urine were collected from day 16 to 20. Rectal temperatures were greater for +LPS vs. –LPS steers at 4 h and lower at 8 h after LPS infusion (LPS × h, P < 0.01). Serum cortisol and plasma urea N were greater for +LPS than − LPS steers at 2 (cortisol only), 4, 8, 12, and 24 h after LPS infusion (LPS × h, P < 0.01). Serum cortisol was greater for +BCAA than − BCAA steers at 12 h after LPS infusion (BCAA × h, P < 0.05). Serum glucose was greater for +LPS than − LPS steers at 2 h after LPS infusion (LPS × h, P < 0.01). Plasma Ile, Leu, and Val were lower, and plasma His was greater in +LPS than − LPS steers (LPS, P < 0.05). Plasma Lys, Met, Thr, and Trp of +LPS steers were lower than − LPS steers at 4 (Thr only), 8 (Lys and Trp only), 12, and 24 h after infusion (LPS × h, P < 0.05). Plasma Ile, Leu, and Val were greater (BCAA, P < 0.01), and Met, His, Phe, Thr, and Trp were lower for +BCAA than − BCAA steers at 0 and 24 h after LPS infusion (BCAA × h, P ≤ 0.05). Steers receiving +LPS had lower rumen pH at 8 h, greater total VFA at 8 h, and lower rumen NH3 at 24 h after LPS infusion compared with − LPS steers (LPS × h, P ≤ 0.04). Total tract passage rates, DM, OM, NDF, ADF, and N intake, fecal N, digested N, and retained N were lower ( P < 0.05) for +LPS than − LPS steers. Total N supply (dietary plus infused) and fecal N were greater ( P < 0.05) for +BCAA vs. − BCAA steers. The absence of LPS × BCAA interactions ( P ≥ 0.20) for N balance indicated that post-ruminal supplementation of BCAA did not alleviate the negative effects of endotoxin on N utilization by growing steers.