Monensin Effects on Digestibility, Methanogenesis and Heat Increment of a Cracked Corn-Silage Diet Fed to Steers

Abstract

Six 300-kg steers were each fed a 70% cracked corn plus corn silage diet at two levels of intake above maintenance with and without 3 mg monensin/kg.75 body weight (W.75). A changeover design was used. Dietary energy and nitrogen were partitioned by duplicate, 22-h indirect respiration calorimetry measurements of heat and methane production on each animal concurrent with 7-d total feces and urine collection trials. Feed and feces were analyzed for energy, N, starch and neutral detergent fiber (NDF). The partial efficiency and(or) heat increment of metabolizable energy (ME) used for gain and maintenance was partitioned by regression of energy storage vs intake. At equalized gross energy intakes (adjustments made by covariance), monensin improved (P less than .01) the apparent digestibilities of energy, from 71.8 to 74.8%; NDF, from 50.5 to 57.5%, and crude protein, from 61.6 to 65.8%. Methane production averaged 5.7% of the control gross energy (GE), but was reduced by 26% (P less than .01) by monensin additions. Metabolizable energy was increased (P less than .01) from 63.3 to 66.8% of gross energy intake by monensin, resulting in an increase (P less than .01) in retained energy (64.7 to 72.3 kcal/W.75). Heat production was increased (P less than .05) by monensin, but only in proportion to the increased ME. Daily energy retentions adjusted to equal ME intake were similar with or without monensin (69.9 vs 67.1 kcal/W.75). No significant effects of monensin on the heat increment of ME use for maintenance or gain were observed. Both NEm and NEg were improved by approximately 7% by monensin; however, the relative effect on NEm vs NEg depends on method of calculation. At equalized GE intakes, approximately one-third of the improved energy utilization was explained by the reduced methanogenesis caused by monensin and two-thirds by reduced fecal losses.

Effects of exogenous fibrolytic enzymes, α-bromoethanesulfonate and monensin on fermentation in a rumen simulation (RUSITEC) system

“…However, the effect of monensin on digestion has been inconsistent in the past. In various in vitro and in vivo studies, monensin has been reported to depress (Poos et al 1979;Mir 1989), to affect minimally (Dinius et al 1976;Lemenager et al 1978;Ricke et al 1984;Faulkner et al 1985) or not at all (Kone and Galyean 1990;Duff et al 1995), and even to increase (Wedegaertner and Johnson 1983) fiber digestibility. Factors such as daily dosage of monensin, ratio of forage to concentrate consumed and differences in ruminal dilution rates or retention times of digesta (Lemenager et al 1978) may also account for this variability.…”

Desempenho de novilhas Holandesas confinadas com dietas com diferentes níveis de monensina sódica

“…Nesses ensaios, independentemente do regime alimentar, a eficiência alimentar também melhorou. Outras influências da monensina em animais em confinamento são: redução na relação acetato:propionato (Raun, 1992), aumento da concentração de ácido propiônico, diminuição da produção de metano e amônia (Badawy et al, 1996), melhora na digestibilidade dos alimentos (Wedegaertner & Johnson, 1983) e controle de coccidiose (Paisley & Horn, 1996). Aparentemente, em todos os experimentos, o aumento da energia disponível, favorecido principalmente pela elevação do ácido propiônico, e a redução da produção dos gases metano e carbônico, diminuíram o consumo (melhorando a digestibilidade) nos animais, em decorrência de uma regulação do balanço Médias seguidas de letras iguais, na linha, não diferem (P>0,05) entre si pelo teste Tukey.…”

Monensin and protein supplements on methane production

“…The toxicity of the ionophores to determined microorganisms can reduce the energetic loss of the diet through enteric methane production. Wedegaertner & Johnson (1983) observed that the effect of monensin in the reduction of the methane production and the loss of energy in the faeces and urine increased the retention of energy in bovines by 19%. Moreover, the methane expelled by the ruminants is presently the focus of criticism, since it presents a greenhouse effect 21 times greater than CO 2 (UNFCC, 2005), a lifespan of 14 years in the atmosphere (IPCC, 1995) and an annual emission estimate, of the Brazilian herd alone, of 9.38 Tg of CH 4 /year (MCT, 2006).…”