Browsing by Subject "Proteins in animal nutrition -- Research"
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Item Foraging behavior and nutrition of grazing steers as influenced by protein supplementation(Texas Tech University, 1988-05) Maiga, Mouslim AStudies were conducted through the growing seasons (April to July) of 1985 and 1986 on tobosagrass (Hilaria mutica [Buckl.] Benth.) rangeland in West Texas. The objective was to evaluate the effects of feeding various levels of cottonseed meal supplement (0.00, 0.34, and 0.68 kg/(hd/d) on the foraging behavior, voluntary intake, dietary selectivity and digestive kinetics in grazing steers. Steers grazed under a 6- paddock short duration grazing system. Length of stay in a paddock was four to seven days. Behavioral observations were made on sixty to seventy steers while grazing in a predetermined paddock. The length of time steers spent at a feeding station, number of bites at a feeding station, number of steps between stations, and total daily grazing time were measured. Indices of foraging efficiency (bite to step ratio, biting rate, feeding time to step ratio, proportion of time spent feeding) were calculated. Particulate passage rate, liquid dilution rate, rumen fermentation, intake and botanical and chemical composition of diets were determined using rumen cannulated and esophageal fistulated steers. Foraging behavior was sensitive to level of supplementation depending upon the grazing cycle and length of stay in a paddock. Supplementation improved foraging efficiency (bite to step ratio, proportion of time spent feeding, feeding time to step ratio) and total daily grazing time as forage availability declined over days within a grazing cycle. Grazing time increased (P < .05) with length of stay in a paddock. Forage intake was not affected (P > .05) by protein supplementation although there was a tendency toward higher intake as level of supplementation increased. Particulate passage rate increased linearly (P < .05) with level of supplementation, while undigested dry matter fill decreased linearly (P < .05) with increasing level of supplementation. Protein supplementation increased (P < .01) liquid dilution rate and turnover rate and decreased (P < .05) turnover time. Total concentrations of volatile fatty acids increased (P < .05) with level of supplementation. However, supplementation did not change (P > .10) molar proportions of acetate, propionate, butyrate and branched chain volatile fatty acids. Rumen ammonia N concentrations were not different (P > .10) between levels of supplementation. Differences due to grazing cycle were noted for forage intake and all the parameters of digestive kinetics. These differences reflected changes in diet botanical composition estimates. Grazing cycle and length of stay in a paddock affected (P < .05) types of forage, plant parts and quality of diets consumed. Supplementation did not alter (P > .10) botanical and chemical composition of diets.