Forty-eight multiparous cows were blocked by calving date and milk production and assigned randomly to a TMR formulated to contain 68 or 55% of dietary CP as ruminally degradable CP. Diets contained corn silage, alfalfa haylage, and ground corn. Supplemental CP was soybean meal for the control diet or a combination of soybean meal, expeller-processed soybean meal, and fish meal for the low degradable protein diet. Two 10-wk phases began on d 31 ± 3 (phase 1) and 110 ± 7 postpartum [phase 2, all cows received subcutaneous implantations of pelleted (400 mg) bST (sometribove) every 14 d]. Dietary energy, CP, ruminally degradable CP, NDF, and ADF were similar between dietary treatments. Production of FCM increased in response to bST but was not affected by dietary treatment. Cows fed the expeller-processed soybean meal and fish meal TMR produced milk that contained less milk fat in phase 1 and less milk protein content in both phases. The DMI, BW, and body condition scores were not affected by diet. Hematocrit, plasma urea N, albumin, total protein, creatinine, glucose, and serum insulin were similar between dietary treatments. Replacing soybean meal with expeller processed soybean meal and fish meal did not affect ruminal degradation of protein or milk production but decreased milk fat and protein contents.
Bibliographical noteFunding Information:
Received November 14. 1991. Accepted April 20. 1992. lPublished as Contribution Number 19.528 of the Scientific Journal Series of the Minnesota Agricultural Experiment Station on research conducted under Project Number 16-045. Supported in part by Minnesota Agricultural Experiment Station and Monsanto Co. 2Present address: The Pennsylvania Stale University. Department of Dairy and Animal Science. University Park 16802. 3Send reprint requests to B. A. Crooker. 130 Haecker Hall. Department of Animal Science. University of Minnesota, 1364 Eckles Avenue. St. Paul 55108.
- expeller soybean meal
- expeller-processed soybean meal
- fish meal
- fish meal
- soybean meal