Bryant T C, Rivera J D, Galyean M L, Duff G C, Hallford D M, Montgomery T H
West Texas A&M University, Canyon 79016-0001, USA.
J Anim Sci. 1999 Nov;77(11):2893-903. doi: 10.2527/1999.77112893x.
Ruminally protected choline (RPC) was evaluated in two experiments. In Exp. 1, beef steers (n = 160; average initial BW = 350.9 kg) were fed a 90% concentrate diet with either 0, .25, .5, or 1.0% RPC (DM basis) for 112 to 140 d. Feeding .25% RPC increased ADG 11.6% compared with 0% RPC, but responses diminished with increasing RPC level (cubic response, P < .10). Daily DMI was not affected by RPC level, but feed:gain was improved 6.8% with .25% RPC compared with 0% RPC, and responses diminished with increasing RPC level (cubic response, P < .10). Carcass yield grade increased linearly (P < .10) as RPC level increased, but marbling score was lower for all three RPC-containing diets than for the 0% RPC diet (quadratic response, P < .05). In Exp. 2, 20 Suffolk lambs (initial BW = 29.8 kg) were fed an 80% concentrate diet for 56 d with the same RPC levels as in Exp. 1. Serum triglycerides (TG) and cholesterol (CLSTRL) were measured in weekly blood samples, and intensive blood samples were collected on d 28 and 56 to evaluate serum insulin (INS), GH, and NEFA. For the 56-d feeding period, ADG responded quadratically (P < .10) to RPC level, but DMI and feed:gain were not affected. Serum INS and NEFA concentrations increased linearly (P < .05) and serum GH responded cubically (P < .05) to RPC level on d 28, but no differences were noted on d 56. Serum TG concentrations in weekly samples increased linearly (P < .10) with RPC level, but, averaged over all weeks, serum CLSTRL concentrations did not differ (P > .10) among treatments. Quantities of carcass mesenteric (P < .05) and kidney fat (P < .10) increased linearly, but longissimus muscle and liver fat contents did not differ (P > .10) among RPC levels. Supplementing RPC in high-concentrate diets improved performance, but results were not consistent among RPC levels or between cattle and sheep. Potential effects of RPC might be mediated through alterations in fat metabolism and(or) metabolic hormones related to fat metabolism.
在两项试验中对瘤胃保护性胆碱（RPC）进行了评估。在试验1中，给160头肉用公牛（平均初始体重 = 350.9千克）饲喂一种90%精料日粮，其中RPC含量分别为0、0.25%、0.5%或1.0%（干物质基础），为期112至140天。与0% RPC相比，饲喂0.25% RPC使平均日增重提高了11.6%，但随着RPC水平的提高反应减弱（三次方反应，P < 0.10）。日采食量不受RPC水平影响，但与0% RPC相比，0.25% RPC使料重比提高了6.8%，且随着RPC水平的提高反应减弱（三次方反应，P < 0.10）。随着RPC水平的提高，胴体产量等级呈线性增加（P < 0.10），但所有三种含RPC日粮的大理石花纹评分均低于0% RPC日粮（二次方反应，P < 0.05）。在试验2中，20只萨福克羔羊（初始体重 = 29.8千克）饲喂一种80%精料日粮，为期56天，RPC水平与试验1相同。每周采集血样测定血清甘油三酯（TG）和胆固醇（CLSTRL），并在第28天和第56天采集强化血样以评估血清胰岛素（INS）、生长激素（GH）和非酯化脂肪酸（NEFA）。在56天的饲喂期内，平均日增重对RPC水平呈二次方反应（P < 0.10），但采食量和料重比不受影响。在第28天，血清INS和NEFA浓度呈线性增加（P < 0.05），血清GH对RPC水平呈三次方反应（P < 0.05），但在第56天未发现差异。每周血样中的血清TG浓度随RPC水平呈线性增加（P < 0.10），但在所有周的平均值中，各处理间血清CLSTRL浓度无差异（P > 0.10）。胴体肠系膜脂肪量（P < 0.05）和肾脂肪量（P < 0.10）呈线性增加，但不同RPC水平间的背最长肌和肝脏脂肪含量无差异（P > 0.10）。在高精料日粮中添加RPC可提高生产性能，但结果在RPC水平之间或牛和羊之间并不一致。RPC的潜在作用可能是通过脂肪代谢和（或）与脂肪代谢相关的代谢激素的改变来介导的。
