Cooke R F, Arthington J D, Staples C R, Thatcher W W, Lamb G C
University of Florida, Institute of Food and Agricultural Sciences, Range Cattle Research and Education Center, Ona 33865, USA.
J Anim Sci. 2007 Oct;85(10):2564-74. doi: 10.2527/jas.2006-684. Epub 2007 May 25.
Two experiments were conducted to compare the performance and physiological responses of forage-fed beef females supplemented with either a molasses-based (ML) or a citrus pulp-based (CT) supplement. In Exp. 1, BW gain, reproductive performance, and concentrations of blood urea N (BUN), plasma glucose, insulin, IGF-I, and progesterone (P4) were assessed in 60 Brahman x Angus heifers supplemented 3 times weekly with either ML or CT. Supplement intakes were formulated to be isocaloric and isonitrogenous. Reproductive performance was not affected by treatments, but mean BW gain was greater (P < 0.01) for heifers fed CT than for those fed ML (0.40 vs. 0.30 kg/d). Mean plasma concentrations of glucose, insulin, and IGF-I were greater (P < 0.05) for heifers fed CT, whereas BUN was greater (P < 0.05) for heifers fed ML. Mean plasma P4 concentration did not differ between treatments, but both groups had lower plasma P4 concentrations during days that supplements were offered (P < 0.01). In Exp. 2, forage DMI and concentrations of BUN, plasma glucose, insulin, IGF-I, and P4 were assessed in 24 Brahman x British mature cows supplemented with the same treatments described in Exp. 1. Overall forage DMI did not differ between treatments, but a day effect and a treatment x day interaction were detected (P < 0.05). Both groups consumed less forage during the days on which the supplements were offered (P < 0.01), and forage DMI for cows fed CT was less (P < 0.05) than for cows fed ML during those days. No differences were detected in any blood or plasma measurement. In addition, no differences in concentrations of P4 were detected between CT- and ML-fed cows. We concluded that CT-supplemented heifers had greater BW gain compared with ML-supplemented heifers, but no differences in reproductive performance were observed. We also observed that CT-supplemented cows had a greater variability in forage DMI compared with ML-supplemented cows.
进行了两项试验，以比较补饲基于糖蜜（ML）或柑橘渣（CT）的补充料的采食牧草的育肥牛的性能和生理反应。在试验1中，对60头婆罗门×安格斯小母牛进行评估，这些小母牛每周补饲3次ML或CT，评估其体重增加、繁殖性能以及血尿素氮（BUN）、血浆葡萄糖、胰岛素、胰岛素样生长因子-I（IGF-I）和孕酮（P4）的浓度。补充料的摄入量按等热量和等氮量配制。处理对繁殖性能没有影响，但补饲CT的小母牛平均体重增加大于（P<0.01）补饲ML的小母牛（0.40对0.30千克/天）。补饲CT的小母牛血浆葡萄糖、胰岛素和IGF-I的平均浓度更高（P<0.05），而补饲ML的小母牛BUN更高（P<0.05）。处理间血浆P4平均浓度没有差异，但在提供补充料的日子里，两组的血浆P4浓度均较低（P<0.01）。在试验2中，对24头婆罗门×英国成年母牛进行评估，这些母牛补饲试验1中所述的相同处理，评估其牧草干物质采食量（DMI）以及BUN、血浆葡萄糖、胰岛素、IGF-I和P4的浓度。处理间总体牧草DMI没有差异，但检测到日效应和处理×日交互作用（P<0.05）。在提供补充料的日子里，两组的牧草采食量均较少（P<0.01），且在那些日子里，补饲CT的母牛的牧草DMI低于（P<0.05）补饲ML的母牛。在任何血液或血浆指标中均未检测到差异。此外，补饲CT和ML的母牛之间未检测到P4浓度的差异。我们得出结论，与补饲ML的小母牛相比，补饲CT的小母牛体重增加更大，但未观察到繁殖性能的差异。我们还观察到，与补饲ML的母牛相比，补饲CT的母牛的牧草DMI变异性更大。
