UBC Theses and Dissertations
The effect of textured and pelleted concentrate on milk component production Gardner, Wendy Christine
Two trials were conducted using Holstein dairy cattle to determine if any difference in milk yield, milk composition and animal food intake occurred when cows were fed either a textured or pelleted concentrate. In the textured concentrate the grain portion was steam flaked with the remainder of the ingredients being pelleted. Both trials used a change-over design where all animals received both diets. In the first trial the animals were classified according to milk production level and were fed textured and pelleted concentrates with alfalfa cubes as the forage source. Cow, period, production level and treatment effects were studied. It was found that animals fed textured concentrate had a significantly (P<0.05) higher milk fat percentage, higher rumen acetate and lower rumen propionate than those fed the pelleted concentrate. In the second trial, textured and pelleted concentrates were fed with a corn:grass silage mixture as the forage. Animals that were fed textured concentrate had a significantly higher silage intake (P<0.05) and concentrate intake (P<0.01) but a significantly lower (P<0.01) milk yield. Milk fat percentage was found to be significantly higher (P<0.01) with the textured feed, although no significant difference was found when fat yield was compared. Milk protein yield was significantly (P<0.01) higher with the pelleted feed while both rumen pH and RBC were lower (P<0.01). Concentrate processing had no significant effect on rumen volatile fatty acid concentration. In the third trial, the degradation characteristics of dry matter (DM) and protein of textured and pelleted concentrates and a corn:grass silage mixture were determined. Concentrates were incubated in nylon bags for up to 72 h and the silage for up to 96 h in the rumen of animals fed an alfalfa and grass hay mixture along with a 16% protein dairy concentrate. The pelleted concentrate had a higher (P<0.01) readily soluble dry matter fraction, readily soluble protein fraction (P<0.01), and effective protein degradability (P<0.05) than the textured concentrate. The results indicate that the feeding of textured concentrate resulted in an increase in milk fat percentage. However, in trial two, feeding textured concentrates did not change milk fat yield while pelleting increased protein yield. The results from trial three indicate that the higher level of heat and moisture involved in steam flaking may act to protect the protein fraction and to decrease the readily degradable dry matter fraction of the concentrate.
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