Cassida K A, Barton B A, Hough R L, Wiedenhoeft M H, Guillard K
Department of Animal, Veterinary, and Aquatic Sciences, University of Maine, Orono 04469.
J Anim Sci. 1994 Jun;72(6):1623-9. doi: 10.2527/1994.7261623x.
Animal performance on brassica diets often does not reflect laboratory estimates of the nutritive value of the herbage. Hay supplementation of brassica pastures should increase diet DM and fiber intake and dilute anti-quality factors. The optimal hay:brassica ratio needed to achieve desirable animal performance, however, has not been established. Effects of changing the hay:brassica ratio on feed and water intake, apparent digestibility of diets, thyroid status, and anemia were examined in five Dorset-cross wether spring lambs (initial BW 32.8 +/- 3.2 kg). The experimental design was a 5 x 5 Latin square with 21-d periods (7 d of adaptation, 6 d of intake measurement, and an 8-d digestion trial with jugular blood drawn on last day). Diets contained chopped grass hay and tyfon (turnip x Chinese cabbage hybrid) at five hay:tyfon ratios (DM basis): 100:0; 75:25; 50:50; 25:75; and 0:100. As the proportion of tyfon in the diet increased, there were linear increases (P < .05) in ad libitum DMI (922 to 1,359 g/d), total water intake (1.75 to 13.06 L/d), digestible DMI (401 to 952 g/d), and apparent digestibility of DM (55.9 to 86.3%), CP (52.9 to 84.5%), and neutral detergent solubles (57.2 to 88.5%). Hay plus tyfon diets exhibited negative associative effects for apparent digestibility of NDF, ADF, and cellulose. Plasma thyroxine and triiodothyronine, packed cell volume, red blood count, and hemoglobin concentration were not affected by diet. Tyfon influenced DMI and apparent digestibility of diets in a manner similar to that of a concentrate.
动物采食芸苔属植物日粮时的表现往往不能反映实验室对牧草营养价值的评估结果。用干草补充芸苔属植物牧场日粮应能增加日粮干物质和纤维摄入量，并稀释抗营养因子。然而，实现理想动物生产性能所需的最佳干草与芸苔属植物比例尚未确定。在5只多塞特杂交去势春羔（初始体重32.8±3.2千克）中，研究了改变干草与芸苔属植物比例对采食量和饮水量、日粮表观消化率、甲状腺状态及贫血的影响。试验设计为5×5拉丁方，每期21天（7天适应期、6天采食量测定期以及最后一天通过颈静脉采血进行8天消化试验）。日粮包含切碎的禾本科干草和泰丰（芜菁×大白菜杂交种），干草与泰丰比例（干物质基础）分别为：100:0；75:25；50:50；25:75；0:100。随着日粮中泰丰比例的增加，随意采食量（922至1359克/天）、总饮水量（1.75至13.06升/天）、可消化采食量（401至952克/天）以及干物质（55.9至86.3%）、粗蛋白（52.9至84.5%）和中性洗涤可溶物（57.2至88.5%）的表观消化率呈线性增加（P<0.05）。干草加泰丰日粮对中性洗涤纤维、酸性洗涤纤维和纤维素表观消化率表现出负协同效应。日粮对血浆甲状腺素和三碘甲状腺原氨酸、红细胞压积、红细胞计数及血红蛋白浓度无影响。泰丰对采食量和日粮表观消化率的影响方式与精料相似。
