Effects of supplementation with narasin, salinomycin, or flavomycin on performance and ruminal fermentation characteristics of Bos indicus Nellore cattle fed with forage-based diets. (16th April 2021)

• Record Type: Journal Article
• Authors: Limede, Arnaldo Cintra; Marques, Rodrigo S; Polizel, Daniel Montanher; Cappellozza, Bruno Ieda; Miszura, Alexandre Arantes; Barroso, José Paulo Roman; Storti Martins, André; Sardinha, Lairana Aline; Baggio, Marcelo; Pires, Alexandre Vaz
• Is Part Of: Journal of animal science. Volume 99:Number 4(2021)
• Publication Date: 2021-04-16
• Subjects: Bos indicus -- digestibility -- feed additives -- forage -- performance -- ruminal parameters; Livestock -- Periodicals; Livestock; Electronic journals; Periodicals; 636.005
• DOI: 10.1093/jas/skab005
• Languages: English
• ISSNs: 0021-8812

Abstract

Abstract: The aim of the present study was to evaluate the inclusion of narasin, salinomycin, or flavomycin for 140 d on ruminal fermentation parameters, apparent nutrient digestibility, and performance of Nellore cattle offered a forage-based diet. In experiment 1, 32 rumen-cannulated Bos indicus Nellore steers [initial body weight (BW ) = 220 ± 12.6 kg] were assigned to individual pens in a randomized complete block design according to their initial shrunk BW. Within block, animals were randomly assigned to 1 of 4 treatments: (1) forage-based diet without feed additives (CON ; n = 8), (2) CON diet plus 13 ppm of narasin (NAR ; n = 8), (3) CON diet plus 20 ppm of salinomycin (SAL ; n = 8), or (4) CON diet plus 3 ppm of flavomycin (FLA ; n = 8). The experimental period lasted 140 d and was divided into 5 periods of 28 d each. The inclusion of feed additives did not impact ( P ≥ 0.17) dry matter intake (DMI ), nutrient intake, and apparent total tract digestibility of nutrients. Nonetheless, steers fed NAR had lower ( P < 0.01) molar proportion of acetate compared with CON, SAL, and FLA steers, whereas ruminal acetate tended to be greater ( P < 0.09) for SAL vs. CON and FLA, but did not differ ( P = 0.68) between CON vs. FLA steers. Ruminal propionate was the highest ( P < 0.01) for steers fed NAR and did not differ ( P > 0.20) between CON, SAL, and FLA. Consequently, NAR steers had the lowest ( P < 0.01) Ac:Pr ratio, whereas Ac:Pr did not differ ( P > 0.18) among CON, SAL, and FLA. Total volatile fatty acids were greater ( P < 0.04) for NAR and CON vs. SAL and FLA, but did not differ ( P > 0.67) among NAR vs. CON and SAL vs. FLA. In experiment 2, 164 Nellore bulls (initial shrunk BW = 299 ± 2.5 kg) were assigned to feedlot pens for 140 d in a randomized complete block design. Within block ( n = 10), animals were randomly assigned to the same treatments used in experiment 1. Average daily gain was greater ( P < 0.01) in NAR vs. CON, SAL, and FLA bulls, and did not differ ( P > 0.12) between CON, SAL, and FLA bulls. Bulls fed NAR had greater ( P < 0.02) DMI (as kg/d or % BW) and final shrunk BW compared with CON, SAL, and FLA bulls, whereas DMI and final shrunk BW did not differ ( P > 0.26) between CON, SAL, and FLA bulls. Feed efficiency, however, was not impacted ( P = 0.51) by any feed additives used herein. Collectively, narasin was the only feed additive that benefited performance and ruminal fermentation of Nellore animals fed a forage-based diet.