Date of Award
Master of Science
M. J. Montgomery
K. M. Barth, B. R. Bell
A feeding trial was conducted to determine the effects upon milk production and milk composition of cows fed either a high degradable protein source or a low degradable protein source. Initially 18 cows were used in a switchback design with three experimental periods. Due to illness and a desire to keep sub class numbers equal, four were dropped. The high degradable protein source consisted of barley, ear corn, shelled corn, soybean meal, salt, and trace minerals ground and ensiled at a 70% dry matter level. The low degradable protein source consisted of brewers dried grains, distillers dried grains, shelled corn, soybean meal (heated to 135°C for eight hours), salt, and trace minerals ground and bagged dry. Each cow received 7 lbs. alfalfa hay, and silage in a 3:2 as fed ratio with concentrate fed free choice to permit 10% refusal. Each experiment period lasted 28 days with the first seven days of each period being an adjustment period. Weekly composition AM and PM milk samples were taken and analyzed for total solids and crude protein. Milkfat data were obtained via the Dairy Herd Improvement Association. Feed samples were taken every 10 days and analyzed for crude protein, crude fiber, acid detergent fiber, ash, dry matter, and ether extract. Protein solubility was determined on the first and last feed samples obtained. Body weights were taken weekly and milk weights were recorded daily. Milk yield and composition between the experimental groups did not differ significantly. Dry matter intake and crude protein intake did differ significantly between groups but was a created difference due to the difference in dry matter between the two diets. Body weights did not differ significantly between the two diets.
Miller, Jeffry Shannon, "Effect of degradability of protein on milk production and composition of early lactation cows. " Master's Thesis, University of Tennessee, 1983.