Influence of Soybean Meal and Sorghum Grain Supplementation on Intake, Digesta Kinetics, Ruminal Fermentation, Site and Extent of Digestion and Microbial Protein Synthesis in Beef Steers Grazing Blue Grama Rangeland

Abstract

Six beef steers (British x Brahman) cannulated at the rumen, duodenum and ileum (avg wt 334 kg) and three mature steers (British x British) cannulated at the esophagus were used in a replicated 3 x 3 latin square design and fed no supplement (C), .5 kg soybean meal (SBM) or .5 kg steam-flaked sorghum grain (SFS).head-1.d-1 (DM basis) while grazing blue grama rangeland. Periods of the latin square included a minimum of 14 d for adaptation and 11 d for esophageal masticate collection and digesta sampling. In September, October and November, respectively, forage collected by esophageally cannulated steers averaged 74.5, 88.8 and 71.0% grasses; 2.06, 1.53 and 1.77% N and 68.3, (P greater than .10) by treatment, but total N intake was greater (P less than .05) for SBM vs C and SFS treatments. No differences (P greater than .10) were detected among treatments in OM, NDF, ADF and N digestibilities in the rumen, small intestine or hindgut, but total tract OM digestibility was greater (P less than .10) for SBM and SFS than for C, and total tract N digestibility was greater (P less than .10) for SBM than for C or SFS. Duodenal ammonia N flow was greater (P less than .05) when SBM was fed that when SFS and C were fed, but microbial N and non-ammonia, non-microbial N flows and microbial efficiency were not altered by treatment. Likewise, ileal N flow was not affected (P greater than .10) by treatment. Particulate passage rate, gastrointestinal mean retention time, forage in vitro OM disappearance and in situ rate of forage NDF digestion also were not affected (P greater than .10) by treatments. Ruminal fluid volume was greater (P less than .05) for SFS vs SBM and C treatments, but no differences were noted in fluid dilution rate. Ruminal fluid ammonia concentration was greater (P less than .05) when SBM was fed than when SFS and C were fed (13.5, 9.9 and 8.7 mg/dl, respectively), whereas pH and total VFA concentrations were not different (P greater than .10). Proportion of acetate in ruminal fluid was less (P less than .10) for SBM and SFS than for C. Small amounts of supplemental SBM and SFS had little effect on forage intake, ruminal fermentation and site of digestion but both increased total tract OM digestion in steers grazing blue grama rangeland.

Suplementação de novilhos mestiços durante a época das águas: parâmetros ingestivos e digestivos

“…Alguns autores têm encontrado efeitos benéficos da suplementação sobre a taxa de passagem (McCOLLUM e GALYEAN, 1985;HANNAH et al, 1991), embora efeitos nulos com o uso de suplementos, sobre este parâmetro, sejam freqüentemente relatados (JUDKINS et al, 1987;KRYSL et al, 1989).…”

“…A possibilidade de seleção de componentes da pastagem de alta digestibilidade, proporcionada pela elevada disponibilidade de massa forrageira (Tabela 3) parece ter influenciado, de forma semelhante, a utilização de nutrientes, possivelmente constituindo entrave ao aparecimento de efeito aditivo na digestibilidade pela inclusão de alimentos de alta digestão à dieta, via suplementação, comumente observado com volumosos de menor qualidade (McCOLLUN e GAYLEAN, 1985;KRYSL et al, 1989;e LINTZENICH et al, 1995).…”

“…O perfil encontrado é condizente com os resultados de KRYSL et al (1989), DelCURTO et al (1991) e LINTZENICH et al (1995. Segundo afirmação de CATON e DHUYVETTER (1997), as fontes energéticas fibrosas tendem a apresentar resultados similares aos grãos, como os encontrados neste trabalho.…”

Effect of nitrogen fertiliser rate and protein supplementation on the herbage intake and the nitrogen balance of grazing dairy cows

“…Under these conditions, a slight increase in herbage intake was reported when cows were supplemented with 2 kg of a concentrate rich in proteins [9]. Similarly, supplements rich in protein increase the herbage intake of beef steers on tropical pastures [23].…”

Suplementação energética de bovinos mantidos em pastagens tropicais com diferentes estratégias de manejo e seus efeitos sobre o consumo de forragem, comportamento ingestivo e parâmetros metabólicos

“…Além disso, dependendo da quantidade de suplemento ingerida pelos animais e do efeito substitutivo sobre a ingestão de massa seca da forragem, o uso desse suplemento pode elevar a ingestão total de massa seca e/ou sua digestibilidade (KRYSL et al, 1989;PORDOMINGO et al, 1991;RUAS et al, 2000;VANZANT et al, 1990), bem como alterar as quantidades e a relação entre os produtos da fermentação ruminal (HESS et al, 1996;VANZANT et al, 1990). Com isso, há aumento na ingestão de energia metabolizável pelos animais suplementados, resultando em economia de aminoácidos glucogênicos, o que aumentaria a eficiência de deposição proteica em animais em crescimento (POPPI; McLENNAN, 1995).…”