Effects of lasalocid, narasin, or virginiamycin supplementation on rumen parameters and performance of beef cattle fed forage-based diet

Abstract

Two experiments were designed to evaluate the impacts of supplementing lasalocid, narasin, or virginiamycin on rumen fermentation parameters, apparent nutrient digestibility, and blood parameters (Exp. 1), as well as feed intake and performance (Exp. 2) of Nellore cattle consuming a forage-based diet. In Exp. 1, thirty-two rumen-fistulated Nellore steers (initial shrunk BW = 355 ± 4.4 kg) were assigned to a randomized complete block design. Within block, animals were randomly assigned to 1 of 4 treatments: 1) forage-based diet without feed additives (CON), 2) CON diet plus 13 mg/kg of DM of narasin (NAR), 3) CON diet plus 20 mg/kg of DM of sodium lasalocid (LAS), or 4) CON diet plus 20 mg/kg of DM of virginiamycin (VRM). No treatment effects were detected (P ≥ 0.32) for intake and apparent digestibility of nutrients. Steers fed NAR had the lowest (P ≤ 0.01) molar proportion of acetate on d 28, 56, and 112 vs. CON, LAS, and VRM steers, whereas acetate did not differ (P ≥ 0.25) between LAS, VRM, and CON steers from d 28 to 84. On d 112, steers fed LAS had a lower (P < 0.02) molar proportion of acetate vs. VRM and CON, whereas it did not differ between CON and VRM (P > 0.33). Steers receiving NAR had a greater (P ≤ 0.04) ruminal propionate vs. CON, LAS, and VRM, whereas LAS steers had greater (P < 0.04) propionate vs. CON and VRM steers on d 28 and 112, and it did not differ (P > 0.22) between CON and VRM. In Exp. 2, one hundred and sixty Nellore bulls were blocked by initial shrunk BW (212 ± 3.1 kg) in a 140-d feedlot trial. Diets contained the same treatments used in Exp.1. Bulls fed NAR had greater (P < 0.02) ADG vs. CON and VRM, and similar (P = 0.17) ADG between NAR and LAS, whereas ADG did not differ (P > 0.28) between LAS, VRM, and CON bulls. A treatment effect was detected (P = 0.03) for DMI, being greater in NAR vs. CON, LAS, and VRM bulls, and similar (P > 0.48) between CON, LAS, and VRM bulls. A tendency was detected (P = 0.09) for feed efficiency, which was greater (P < 0.02) in NAR bulls vs. CON and VRM, and similar (P = 0.36) between NAR and LAS bulls. From d 112 to 140, bulls receiving NAR were heavier (P < 0.03) vs. CON, LAS, and VRM bulls, but no differences were observed (P > 0.51) between CON, LAS, and VRM bulls. Collectively, ruminal fermentation profile and intake were impacted by narasin supplementation, which partially contributed to the enhanced performance of Nellore bulls receiving a forage-based diet.

Farm-Scale Effectiveness of Feed Additives Supplied through a Mineral Mix for Beef Cattle Grazing Tropical Pastures

“…Liver abscesses are more often reported in highconcentrate feedlot diets, which is not the case in the present study. Shifts in ruminal fermentation due to virginiamycin supplementation towards more propionate and less lactate are reported for animals fed high-concentrate diets [43] but not for forage-based diets [8,38,44]. Results regarding rumen parameters from the present study corroborate the latter authors.…”

“…Livestock producers worldwide constantly seek ways to enhance the efficiency and profitability of their production systems [1,2]. Several authors have reported increased efficiency and/or performance of animals fed feed additives, such as ionophores and nonionophore antibiotics, in both high-concentrate [3][4][5][6] and forage-based [7,8] diets. The latter studies, however, were carried out in housed facilities with animals fed in feed troughs.…”

“…Stapf cv. Xaraés; 5 C. dactylon (L.) Pers.,6 Values estimated from Valadares et al[31],7 Crude protein,8…”

Effect of forage quality and narasin inclusion on ruminal fermentation, nutrient intake, and total tract digestibility of Nellore steers

“…Using ionophores also results in better energy retention efficiency, use of nitrogen from the diet, mitigation of methane production, and lower occurrence of metabolic disorders ( McGuffey et al, 2001 ). Narasin is a monovalent ionophore that increases the concentration of ruminal propionate and total SCFA and reduces acetate:propionate ( Ac:Prop) ratio of animals consuming forage-based diets ( Polizel et al, 2020 ; Limede et al, 2021 ; Miszura et al, 2023 ). However, none of our earlier studies demonstrated an improvement in digestibility when narasin was given to animals eating diets based on forage, despite the fact that the forage quality varied between these studies ( Polizel et al, 2020 —average CP = 10.3%; Limede et al, 2021 —average CP = 17.6%; Soares et al, 2021 —CP = 20.8%; Miszura et al, 2023 —average = CP 12%).…”

Effects of increasing levels of lasalocid supplementation on growth performance, serum biochemistry, ruminal fermentation profile, in vitro nutrient digestibility, and gas production of growing goats

“…Lasalocid has been shown to have positive effects on lipid metabolism in cows and sheep, including an increase in high-density lipoprotein (HDL) levels. Higher levels of HDL have been associated with a lower risk of cardiovascular disease, indicating the potential benefits of lasalocid supplementation in improving animal health and productivity ( 16 ). Recent literature reviews have highlighted the potential benefits of LAS supplementation for improving animal performance and welfare.…”