Nitrogen Utilization and Digestibility by Growing Steer and Goats of Diets that Contain Monensin and Low Crude Protein

Abstract

Two digestion and metabolism experiments were conducted to determine effects of monensin in low-protein diets. Monensin supplementation (27 mg/kg of diet dry matter) of steers (303 kg) fed 8.7% crude protein increased (P less than .01) apparent N digestibility and N retention and decreased (P less than .01) percentage of N apparently absorbed lost in urine. Apparent digestibilities of dry matter, gross energy and acid detergent lignin were increased (P less than .05). Digestibilities of neutral detergent and acid detergent fibers were not affected by monensin. In growing wether goats (15 kg) fed 8.5% crude protein, monensin (23 mg/kg of diet dry matter) improved (P less than .01) apparent N digestibility and apparent N absorption. However, urinary N excretion also increased (P less than .05), resulting in no difference in N retention. Monensin did not affect digestibilities of dry matter or gross energy. Efficiency of feed conversion and average daily gain were improved with monensin supplementation of growing goats fed a low-protein, high-roughage diet. Monensin resulted in typical shift of acetate-to-propionate ratio in both experiments. Results suggest that improved N utilization may account for some benefits of feeding monensin.

Growth promoters and meat yield

“…Improvement of gain was much more pronounced in grazing cattle. Furthermore, the digestibility of grass was improved by feeding lasalocid, lysocellin, monensin and salinomycin (68,69,38,70,63). This variability in response between finishing and grazing cattle may be explained by two different feed intake mechanisms.…”

Monensina para bezerros ruminantes em crescimento acelerado: 2. Digestibilidade e parâmetros ruminais

“…Foi encontrada regressão linear (P<0,05) para os coeficientes de digestibilidade aparente, bem como para NDT, ED, MSD, PD e FDND, em que os valores se elevaram com o aumento dos níveis de monensina. Os coeficientes de digestibilidade apa- (SCHELLING, 1984;MEDEL et al, 1991) da MS e FDN, em novilhos canulados no rúmen e no duodeno (FAULKNER et al, 1985), da MS e EB em novilhos alimentados com dieta pobre em proteína (BEEDE et al, 1986) e da MS, PB e FB, em dietas altas e baixas em fibras, em novilhos Holandeses (ARAUJO-FEBRES e FERNÁNDEZ, 1991). Houve também aumento na digestibilidade da MS e EB, em novilhos alimentados com dietas concentradas e adaptados com monensina (Beede et al, 1980, citados por SCHELLING, 1984.…”

Integration of pasturing systems for cattle finishing programs

“…Callaway et al (1997) also found that monensin and nicin inhibited starch fermentation in vitro by 30 and 60 %, respectively. Beede et al (1986) designed an experiment to study the effect of monensin on N utilization by growing steers and goats fed diets low in crude protein and measured apparent dry matter, gross energy, fiber digestibilities and growth performance of growing goats.…”

“…Monensin fed cattle have shown better performance and efficiencies. When Goodrich et al (1984) Beede et al (1986) conducted two digestion and metabolism trials to determine effects of monensin in low-protein diets. In the first experiment they fed 303 kg steers with a control diet that contained 8.7 % crude protein and monensin in the amount of 27 mg/kg of diet dry matter.…”