Combinations of starch and digestible fiber in supplements for steers consuming a low-quality bromegrass hay diet

Abstract

Five steers (690 kg) with ruminal and duodenal cannulas were fed 100% bromegrass hay or 60% bromegrass hay:40% concentrate at 90% of their ad libitum DMI. The concentrate consisted of ground corn (GC) and(or) soybean hulls (SBH): 1) 100% SBH; 2) 66% SBH/33% GC; 3) 33% SBH/66% GC; or 4) 100% GC. Increasing level of corn inclusion decreased (linear, P < .01) DM and OM digestion (corrected for microbial DM and OM flow) in the rumen. Neutral detergent fiber digestion decreased in the rumen (quadratic, P = .05) and total tract (linear, P = .06) with increasing level of corn. Ruminal NDF digestion (quadratic, P = .05) and duodenal microbial N flow (quadratic, P < .01) were greatest for 66% SBH/33% GC, whereas total N flow to the duodenum was similar (P > .10) among treatments. Microbial efficiency increased (quadratic, P = .10) as the level of corn inclusion increased. Molar percentage of ruminal acetate decreased (linear, P < .01) with increasing level of corn, whereas molar percentage of butyrate increased (linear, P < .10). Carboxymethylcellulase activity was greatest (quadratic, P = .08) for 66% SBH/33% GC and paralleled NDF digestion in the rumen. Increasing level of corn decreased (linear, P < .07) in situ DM digestibility of SBH after 4, 8, and 12 h of incubation.

Desempenho de novilhos Nelore alimentados com casca de soja ou farelo de gérmen de milho em substituição parcial ao milho moído

“…Quando introduzidos casca de soja e farelo de gérmen de milho em substituição parcial ao milho moído, pode haver influência positiva sobre o ecossistema ruminal (Mendes et al, 2006). Experimentos anteriores comprovaram que a suplementação de bovinos com casca de soja provocou efeito negativo sobre a digestão da fibra menor que a suplementação com milho (Anderson et al, 1988;Grigsby et al, 1993).…”

Effect of rumen degradable energy supplementation on forage utilization and performance of steers grazing stockpiled cool season perennial grass pastures

“…It is also unlikely that rumen pH was negatively affected by the HSLF pellet to the point where forage fibre intake and digestibility would be negatively impacted. Grigsby et al (1993) reported that ruminal pH was only slightly decreased from 6.3 to 6.2 when beef steers fed low-quality grass hay went from 100% soybean hulls to 100% ground corn supplementation. It should also be pointed out that the two pellets were equal in CP and soluble CP content.…”

Desempenho e digestibilidade de novilhos zebuínos confinados recebendo leveduras vivas e monensina

“…Apesar de ser um alimento que é altamente fermentável no rúmen, este não promove uma acidificação tão acentuada do ambiente ruminal quanto o ácido láctico, produto da fermentação do amido, uma vez que o resultado da fermentação de carboidratos estruturais é o ácido acético, sabidamente um ácido fraco. Tal fato é comprovado pelo estudo de Grigsby et al (1993) que verificaram um aumento linear no pH ruminal com o aumento da substituição do milho pela casca de soja no concentrado da dieta de novilhos.…”