Escape protein for beef cows: II. Source and level in ammoniated wheat straw-corn silage diets.
Two experiments, using Angus x Hereford spring-calving beef cows in mid- or late lactation nursing Simmental-sired calves, were conducted to evaluate the relative value of a corn gluten meal-blood meal mixture (CGM-BM; 50% of supplemental protein from each source). In Exp. 1 (78 d), cows in late lactation were assigned to one of three treatments: control at 8.2% CP (C), soybean meal at 10.4% CP (SBM), or CGM-BM at 10.3% CP. Diets were calculated to be isocaloric at 55% TDN. In Exp. 2 (65 d), cows in mid-lactation were assigned to four treatments: urea, SBM, low CGM-BM (LM), and high CGM-BM (HM). Diets in Exp. 2 were isonitrogenous (9.5% CP) and isocaloric (55% TDN). Diets in both experiments were based on ammoniated wheat straw and corn silage. Weight gains of cows and cow-calf pairs were greater (P less than .06) when protein was supplemented in Exp. 1. Gains were lower for cows fed urea (P less than .03) in Exp. 2 but were similar when cows were supplemented with SBM vs either the low or the high level of CGM-BM. Performance of calves did not differ among dietary treatments.
De Gracia
M
M
University of Nebraska, Lincoln 68583-0908.
Ward
J K
JK
D000821:Animal Feed; D000818:Animals; D002417:Cattle / Q000254:growth & development* / Q000502:physiology; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D007774:Lactation / Q000502:physiology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D012820:Silage; D013025:Glycine max; D014908:Triticum; D014508:Urea / Q000008:administration & dosage; D015430:Weight Gain; D003313:Zea mays
D004044:Dietary Proteins; D014508:Urea