Phillip L E, Hidalgo V
Macdonald College, McGill University, Ste. Anne de Bellevue, Quebec.
J Anim Sci. 1989 Aug;67(8):2116-22. doi: 10.2527/jas1989.6782116x.
An experiment with growing lambs was designed to test the hypothesis that alterations in blood acid-base status would influence intake of corn silage. Six wethers (29 kg) were fed a diet of corn silage (36% DM, 8% CP) supplemented with 1.25% urea and .2% sulfur. At feeding time, sodium bicarbonate (NaHCO3) and sodium sesquicarbonate (NaSC) were added to the silage at levels of 0, 2% or 4% of diet DM. The treatments were arranged as a 2 x 3 factorial, and the study was conducted as a 6 x 4 incomplete latin square with four 17-d periods. Voluntary intake of OM was not different (P greater than .05) between NaHCO3 (1,008 g/d) and NaSC (1,041 g/d). There was no significant interaction between type of buffer (NaHCO3 or NaSC) and level of buffer on any of the variables measured. The progressive increase in buffer load did not alter feed intake (P greater than .05), although there was a quadratic response (P less than .05) in urine pH and a linear increase (P less than .01) in blood HCO3- 2 h after feeding. There was no evidence that lambs fed corn silage experienced metabolic acid stress. Urinary excretion of ammonia and urea were indicative of changes, although not pronounced, in ammoniuria and ureapoiesis in response to bicarbonate loading. This study implies that corn silage imposes no "acid stress" on lambs and, consequently, that there is no nutritional benefit in adding buffers to corn silage for sheep.
设计了一项关于生长羔羊的实验，以检验血液酸碱状态的改变会影响玉米青贮饲料摄入量这一假设。选用6只阉羊（体重29千克），给它们饲喂添加了1.25%尿素和0.2%硫的玉米青贮饲料（干物质含量36%，粗蛋白含量8%）。在喂食时，将碳酸氢钠（NaHCO₃）和倍半碳酸钠（NaSC）以日粮干物质的0%、2%或4%的水平添加到青贮饲料中。处理方式按2×3析因设计，研究以6×4不完全拉丁方进行，共4个17天的周期。NaHCO₃组（1008克/天）和NaSC组（1041克/天）之间的有机物质自愿摄入量没有差异（P大于0.05）。在所测的任何变量上，缓冲剂类型（NaHCO₃或NaSC）和缓冲剂水平之间均无显著交互作用。缓冲剂负荷的逐渐增加并未改变采食量（P大于0.05），不过喂食后2小时尿液pH呈二次响应（P小于0.05），血液HCO₃⁻呈线性增加（P小于0.01）。没有证据表明饲喂玉米青贮饲料的羔羊经历了代谢性酸应激。氨和尿素的尿排泄量表明，对碳酸氢盐负荷的响应中，氨尿症和尿素生成虽不明显但有变化。本研究表明，玉米青贮饲料不会给羔羊带来“酸应激”，因此，给绵羊的玉米青贮饲料添加缓冲剂没有营养益处。
