@article{zimmerman_rakes_daniel_hopkins_1992, title={EFFECT OF TOTAL AND RUMEN UNDEGRADABLE PROTEIN ON THE PERFORMANCE OF COWS FED LOW-FIBER DIETS}, volume={75}, ISSN={["0022-0302"]}, DOI={10.3168/jds.S0022-0302(92)77955-7}, abstractNote={Twelve multiparous and 18 primiparous Holstein cows were fed a 17.3% CP, 21.0% ADF diet during wk 2 through 6 postpartum. Cows then were assigned from wk 7 through 14 to one of three low fiber (10.7% ADF) dietary treatments containing either 14.4 or 18.7% CP, the latter with or without a soybean meal enhanced with rumen undegradable protein. Treatments had no effect on milk yield or composition in multiparous cows, although milk fat percentage was not depressed in multiparous cows receiving the low fiber diets. The soybean meal diet enhanced with rumen undegradable protein increased yields of milk, 4% FCM, fat, protein, and DMI compared with the 14.4% CP diet in primiparous cows; it also increased yields of 4% FCM and fat versus the 18.7% CP, untreated diet in primiparous cows. Blood urea N concentrations were greater for high CP diets than for the low CP diet in both parity groups. Rumen acetate: propionate ratios were higher for both high CP diets than for the low CP diet in multiparous cows. Soybean meal enhanced with rumen undegradable protein improved yields of milk and its components in primiparous cows fed low fiber diets, even when high protein diets were fed.}, number={7}, journal={JOURNAL OF DAIRY SCIENCE}, author={ZIMMERMAN, CA and RAKES, AH and DANIEL, TE and HOPKINS, BA}, year={1992}, month={Jul}, pages={1954–1964} }
 @article{zimmerman_rakes_daniel_hopkins_1992, title={INFLUENCE OF DIETARY-PROTEIN AND SUPPLEMENTAL NIACIN ON LACTATIONAL PERFORMANCE OF COWS FED NORMAL AND LOW-FIBER DIETS}, volume={75}, ISSN={["0022-0302"]}, DOI={10.3168/jds.S0022-0302(92)77956-9}, abstractNote={Forty-seven cows (24 primiparous) were assigned to one of four normal (20.5%) ADF diets for wk 2 to 5 postpartum. Dietary treatments in a 2 x 2 factorial design were diets of 13.8 versus 18.8% CP and 0 versus 12 g/d of niacin per cow. During wk 6 to 13 postpartum, cows were fed low (11.8%) ADF diets while maintaining CP and niacin treatments. Low CP diets contained solvent-extracted soybean meal; rumen soybean meal with enhanced undegradable protein was used in high CP diets. High CP diets increased milk protein percentage in multiparous cows and yields of milk, 4% FCM, fat, protein, and SNF in primiparous cows during the normal fiber period. High dietary CP also increased yields of 4% FCM, fat, protein, and SNF in primiparous cows fed normal fiber diets. When switched to low fiber diets, primiparous cows fed high CP diets decreased more in 4% FCM and fat yields than those fed low CP. Primiparous cows fed niacin decreased more in 4% FCM than controls. High dietary CP increased DMI in primiparous cows fed normal fiber diets, but those fed low CP diets increased more in DMI when switched to low fiber diets. Supplemental niacin appeared to interact with dietary CP in multiparous cows, increasing blood glucose and decreasing blood beta-hydroxybutyrate and NEFA concentrations with the high CP, normal fiber diet. Increased dietary CP improved yields of milk and milk components in primiparous cows.}, number={7}, journal={JOURNAL OF DAIRY SCIENCE}, author={ZIMMERMAN, CA and RAKES, AH and DANIEL, TE and HOPKINS, BA}, year={1992}, month={Jul}, pages={1965–1978} }
 @article{zimmerman_rakes_jaquette_hopkins_croom_1991, title={EFFECTS OF PROTEIN LEVEL AND FORAGE SOURCE ON MILK-PRODUCTION AND COMPOSITION IN EARLY LACTATION DAIRY-COWS}, volume={74}, ISSN={["0022-0302"]}, DOI={10.3168/jds.S0022-0302(91)78247-7}, abstractNote={Twenty multiparous and 12 primiparous Holstein cows were assigned at calving to one of three grass hay-based diets containing either 14, 18, or 22% CP or an alfalfa hay-based diet containing 22% CP to examine the effect of protein level and forage source on milk yield and composition. The diets contained 23% ADF during wk 1 to 4 postpartum, which was lowered to 11% for wk 5 to 12 postpartum. Cows fed the 18 and 22% CP grass-based diets produced higher yields of milk, 4% FCM, fat, protein, and SNF than those fed the 14% CP diet during the high fiber period. In addition, cows fed the 22% CP grass-based diet had higher milk fat tests than those fed the 14% CP diet during the high fiber period, due primarily to an increase in short-chain fatty acid synthesis. Milk fat depression was more severe when cows were changed to low fiber diets while fed the 22% CP alfalfa-based diet than when fed the 22% CP grass-based diet. Depression in milk fat content was 15.0, 17.0, 15.6, and 27.0% for 14, 18, and 22% CP grass-based and 22% CP alfalfa-based diets, respectively. Cows receiving the 18 and 22% CP grass-based diets exhibited higher blood NEFA during the high fiber feeding period than those fed the 14% CP diet. After fiber was lowered, changes in rumen acetate:propionate ratios were unaffected by treatment. Lowering fiber level resulted in an increased milk CP percentage regardless of treatment. Grass hay appeared to be more effective than alfalfa hay in preventing depression in milk fat test upon the change to a low fiber diet.}, number={3}, journal={JOURNAL OF DAIRY SCIENCE}, author={ZIMMERMAN, CA and RAKES, AH and JAQUETTE, RD and HOPKINS, BA and CROOM, WJ}, year={1991}, month={Mar}, pages={980–990} }
 @article{zimmerman_rakes_daniel_hopkins_1990, title={Effect of rumen undegradable protein on lactational performance in cows fed low fiber diets}, volume={73}, journal={Journal of Dairy Science}, author={Zimmerman, C. A. and Rakes, A. H. and Daniel, T. E. and Hopkins, B. A.}, year={1990}, pages={169} }
 @article{zimmerman_rakes_jaquette_hopkins_croom_1989, title={Effects of dietary protein level and roughage source on milk fat depression in cows fed low fiber diets}, volume={72}, journal={Journal of Dairy Science}, author={Zimmerman, C. A. and Rakes, A. H. and Jaquette, R. D. and Hopkins, B. A. and Croom, W. J., Jr.}, year={1989}, pages={490} }