Narasin inclusion for feedlot lambs fed a diet containing high amounts of ground flint corn

Abstract

Narasin is an antibacterial agent that may change rumen fermentation. Two experiments were proposed to evaluate the efficiency of narasin inclusion for lambs fed a diet containing high amounts of ground flint corn. Thirty rumen-cannulated wethers were used to evaluate nutrient digestibility, nitrogen balance, and rumen metabolism (Exp. 1); and forty-five lambs were used to evaluate performance (Exp. 2) of animals fed with narasin for high flint corn diets. The experimental diets were: control or basal diet without additives (C); 25 mg of monensin kg-1 of dry matter (DM) (M); and inclusion of 5 (N5), 10 (N10), and 15 (N15) mg of narasin kg-1 of DM. The statistical analyses were performed using the MIXED procedure of SAS. Monensin increased DM digestibility compared to C (p = 0.01) and increasing doses of narasin linearly increased DM digestibility (p < 0.01). There was a quadratic effect (p = 0.10) for molar proportion of acetate peaking at N15. Monensin inclusion increased (p = 0.07) propionate compared to C; however, it did not differ from narasin. The increasing levels of narasin linearly decreased the total volatile fatty acids concentration in the rumen (p = 0.02). Monensin and C showed a similar performance. The increasing levels of narasin linearly increased (p ≤ 0.04) average daily gain and feed efficiency. Monensin and narasin changed rumen fermentation and improved overall nutrient digestibility. However, lambs that received narasin showed improved performance when compared with animals that received M.

Residual effect of narasin on feed intake and rumen fermentation characteristics in Nellore steers fed forage-based diet

“…Although narasin has similar results to monensin in handling ruminal fermentation parameters and nutrient digestibility ( Polizel et al, 2021 ), data in the literature show that narasin does not impact DMI in high-concentrate ( Polizel et al, 2021 ) or forage-based diets ( Limede et al, 2021 ; Polizel et al, 2020 ). These results suggest that narasin might be a favorable nutritional tool in multiple supplements, as DMI has a high-positive correlation with animal performance.…”

“…The inclusion of ionophores into beef cattle diets alters SCFA dynamics by changing ruminal bacterial communities, resulting in more efficient fermentation pathways ( Prange et al, 1978 ), increasing energy recovery from hexoses ( Raun, 1990 ), and metabolizable energy availability ( Tedeschi et al, 2003 ). The inclusion of narasin into the diet reduced the molar concentration of acetate in concentrate- ( Polizel et al, 2021 ) or forage-based diets ( Limede et al, 2021 ; Polizel et al, 2020 ). Bell et al (2017) observed that acetate concentration remained lower after monensin withdrawal than in control diets until day 7.…”

Narasin improves ewe milk yield efficiency and may affect performance of lambs

“…The use of ionophores in ruminant diets is usually associated to a reduction in DM consumption, especially when monensin is used (Duffield et al, 2012;Polizel et al, 2021b). On the other hand, recent studies evaluating the use of narasin in ruminant diets indicate that this ionophore does not reduce DMI when added to diets with high levels of roughage (Pasqualino et al, 2020; or concentrate (Polizel et al, 2021a). Moreover, Assis et al (2020) related that when supplied at a dose of 13 mg kg -1 of DM, narasin increased DMI of lactating ewes.…”

“…Narasin is an ionophore approved by the Brazilian Ministry of Agriculture, Livestock, and Supply in 2015 (MAPA, 2020) for use as feed additive for ruminants. Since its approval, several studies have been conducted and demonstrated the positive effects of narasin on ruminal fermentation (Pasqualino et al, 2020;Polizel et al, 2020) and animal performance (Gobato et al, 2020;Polizel et al, 2021a). To our knowledge, the only studies that evaluated the use of narasin in lactating ewes demonstrated its potential to increase milk yield and efficiency when ewes were fed diets with ground corn as main energy source (Assis et al, 2020) or a mix of ground corn and citrus pulp (Sardinha et al, 2020).…”

Dietas sem forragem à base de grãos de milho inteiros ou moídos na terminação de cordeiros

“…A maior absorção de N pelos animais que receberam a dieta CONT foi devido sua maior disponibilidade, já que a ingestão de PB (Tabela 3) pelos animais das dietas sem forragem foi abaixo do ideal (NRC, 2007). Os resultados encontrados para os animais que receberam a dieta CONT no presente experimento foi similar ao reportado por outros autores utilizando dietas com alto teor de concentrado (ECKERMANN, 2020;CARLIS, 2021;POLIZEL et al, 2021aPOLIZEL et al, , 2021b.…”