Frequency of narasin intake affects ruminal metabolism and growth of lambs

Oliveira, Gabriela B; Polizel, Daniel Montanher; Bertoloni, Analisa Vasques; Ferraz, Marcos Vinícius de Castro; Miszura, Alexandre Arantes; Barroso, Juliana Machado; Martins, André S; Pasqualino, Letícia; Biava, Janaína Socolovski; Ferreira, Evandro Maia; Pires, Alexandre Vaz

doi:10.1071/an20418

Cited by 1 publication

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“…There is no consensus in the literature on the effects of narasin on ruminal SCFA concentration. In diets with high forage content, the inclusion of ionophore increased the total SCFA concentration ( Oliveira et al, 2022 ; Polizel et al, 2020 ), while in diets with high concentrates, the total SCFA concentration decreases ( Polizel et al, 2021 ). In agreement with the results reported by Pasqualino et al (2020) , the present study demonstrated that there is no residual effect of narasin on the SCFA concentration in the rumen fluid after the removal of the ionophore.…”

Section: Discussionmentioning

confidence: 99%

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

Soares

Marques

Pires

et al. 2023

Translational Animal Science

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This study aimed to evaluate the residual effect of narasin on intake and ruminal fermentation parameters in Nellore cattle fed a forage-based diet. Thirty rumen-cannulated Nellore steers [initial body weight (BW) = 281 ± 21 kg] were allocated to individual pens in a randomized complete block design, with 10 blocks and 3 treatments, defined according to the fasting BW at the beginning of the experiment. The animals were fed a forage-based diet containing 99% Tifton-85 haylage and 1% concentrate. Within blocks, animals were randomly assigned to 1 of 3 treatments: 1) forage-based diet without addition of narasin (CON; n = 10), 2) CON diet plus 13 mg of narasin/kg DM (N13; n = 10), or 3) CON diet plus 20 mg of narasin/kg DM (N20; n =10). The experiment lasted 156 days and was divided into 2 periods. The first period lasted 140 days and consisted of the daily supply of narasin. In the second period (last 16 days) the animals were not supplemented with narasin when the residual effect of the additive was evaluated. The treatments were evaluated by linear and quadratic orthogonal contrasts. The results were reported as least square means and the effect was considered significant when P ≤ 0.05. No treatment × day interaction was identified for dry matter intake (DMI; P = 0.27). There was a treatment × day (P ≤ 0.03) interaction after narasin removal for the molar proportion of acetate, propionate, ac:prop ratio and ammonia nitrogen. The inclusion of narasin decreased linearly (P < 0.01) the molar proportion of acetate (P < 0.01), and this effect persisted until day 5 after narasin withdrawal (P < 0.01). Narasin inclusion linearly increased the molar proportion of propionate (P < 0.04), and linearly decreased (P < 0.01) ac:prop ratio up to 5 days after removing narasin from the diets. No treatment effects were observed (P > 0.45) on days 8 and 16 after the withdrawal. Narasin linearly decreased ammonia nitrogen up to 1 day after withdrawal (P < 0.01). In conclusion, the use of narasin for a prolonged period (140 d) resulted in a residual effect on rumen fermentation parameters after the removal of the additive from the diets.

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