Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)


Animal Science

First Advisor

Lawrence D. Muller


In experiment I a series of in vitro buffer and rumen fermentation studies were conducted to evaluate protein solubility at pH 6.8 and pH 2.5 (with pepsin) and ammonia production from whey protein concentrates (WPC, 55% protein) treated with 0, .25, .5, 1.0, and 3% formaldehyde; 1, .5, 1.0, 2.0, 3.0, and 6% tannic acid; and 0, 1, 2, and 3 hr of heat treatment at 104 C. Protein solubility and ammonia production from casein treated with 0, .5, 1.0, and 3% formaldehyde and 0, .5, 1.0, and 3% tannic acid were also studied. All levels of formaldehyde treatment of WPC depressed (P<.01) protein solubility at pH 2.5 was about 33% (P<.01) of the control. All the levels of formaldehyde reduced ammonia production (P<.01) indicating protection of WPC from degradation in the rumen. Protein solubility of WPC at pH 6.8 was depressed by 2.0, 3.0, and 6.0% tannic acid (P<.01) compared to the control, but all the levels of WCP-tannic acid treatment were highly soluble at pH 2.5. Ammonia production from WPC-tannic acid did not differ from the control, although 6% tannic acid reduced (P<.05) ammonia production. All the WPC-heat treatments greatly reduced (P<.01) protein solubility at pH 6.8 and reduced solubility by 50% at pH 2.5. Ammonia production was reduced to about 20% of the control in all the heat treatments. All levels of formaldehyde reduced ammonia production but only 1 and 3% differed (P<.01) from the control. All casein-tannic acid treatments were highly soluble at both pH 6.8 and pH 2.5 and did not differ from the control. Only 3% tannic acid reduced (P<.01) ammonia production from the control. Mice were fed similarly treated WPC or casein in a 17% protein ration to evaluate the extent of protein protection. Mouse growth was comparable to the control when .25 and .5% formaldehyde treated rations were fed, but mouse growth was decreased (P<.01) with the 1% formaldehyde treated ration. Although feed consumption of WPC-tannic acid treatments (except 6% tannic acid) was similar to the control, growth decreased as the levels of tannic acid increased in the ration. All the ice fed heat treated rations consumed similar amount of feed as the control group. Mice fed WPC-heat treatment (1 hr) gained weight about 60% of the control. Mice fed rations heated 2 and 3 hr gained less weight as the heating time increased. In experiment II four lactating Holstein cows were fed isonitrogenous rations of urea-corn silage and a 15% crude protein, pelleted grain ration containing whey protein concentrate (34% protein) either untreated (U_WPC) or treated (T_WPC) with 1% formaldehyde on a protein basis. The trial design was a three period double reversal with 12 days per period during which milk and digestibility parameters were measured the last 4 days of each period. Apparent nitrogen digestibility (%), productive nitrogen retained (milk plus retained, g/day), and dry matter digestibility were 60.0 and 53.9 (P<.05), 89.0 and 103.8, and 67.4 and 63.2 for cows fed U_WPC and T_WPC rations, respectively. Productive nitrogen as a percent of absorbed was greater for cows fed the T_WPC ration, suggesting more efficient utilization of absorbed nitrogen. Milk production (kg/day), fat (%), faty [sic] yield (kg/day), and 4% fat-corrected milk (kg/day) were 27.6 and 29.4, 3.1 and 3.4, .86 and 1.00 (P<.05), and 23.7 and 26.9 for cows fed the U_WPC and T_WPC rations, respectively. Total milk nitrogen (g/day), true protein nitrogen (g/day), and casein nitrogen (g/day) were 135.84 and 140.90, 132.84 and 137.30, and 118.95 and 124.13 for cows fed U_WPC and T_WPC rations, respectively. No differences were found in rumen ammonia or blood urea. Ruman volatile fatty acids were higher in cows fed U_WPC ration at 4 and 6 hr postfeeding. Only milk fatty acid 16:0 was greater (P<.05) in cows fed U_WPC ration than in cows fed T_WPC ration. Differences in total and most essential amino acids between tail and mammary blood were greater for cows fed T_WPC ration.

Library of Congress Subject Headings

Animal nutrition
Proteins -- Research




South Dakota State University