【作者】 王吉峰；

【导师】 王加启；

【作者基本信息】 中国农业科学院 ， 动物营养与饲料科学， 2004， 博士

【摘要】 本研究用4头安装永久瘤胃瘘管和十二指肠瘘管的泌乳奶牛（体重为483±21kg，泌乳日龄为175±6天）通过4×4拉丁方试验设计，研究在不同精粗比日粮条件下苜蓿、羊草、玉米青贮及精料在奶牛瘤胃内动态降解率及其降解参数、纤维酶活性、瘤胃发酵模式及奶牛生产性能，同时研究日粮对泌乳奶牛DM、OM、NDF及ADF消化率、物理有效中性洗涤纤维（peNDF）及乳脂肪酸成分的影响。4种不同日粮分别为30：70CW（粗料仅由羊草组成）、30：70CCA（粗料为玉米青贮+苜蓿+羊草）、50：50CCA、65：35CCA，共设4期试验，每期23天。通过尼龙袋法（in situ）研究表明，瘤胃降解参数a、b、c值在不同日粮组均无显著差异（P＞0.10）：有效降解率以精料最高，羊草最低（P＜0.01）；在30：70CW日粮条件下，苜蓿12h降解率（P＜0.05）、玉米青贮12h降解率（（P＜0.10）均低于其它日粮组，而羊草在高精料65：35CCA日粮组6-24h时显著低于其它日粮组（P＜0.05）；且瘤胃内pH值显著低于其它组（P＜0.01），在晨饲后4-6h低于6.1，瘤胃纤维分解酶活性有下降趋势（P＜0.10）。65：35CCA及50：50CCA日粮组瘤胃内氨氮浓度显著高于30：70日粮组（P＜0.01），瘤胃内乙酸浓度随精料比例的提高而降低（P=0.10），丙酸浓度、丁酸浓度及乙酸／丙酸比例差异极显著（P＜0.01）：30：70CCA日粮组乳脂率极显著高于30：70CW（P＜0.01）。65：35CCA组产奶量、乳蛋白率及非乳脂固形物含量均极显著高于其它组（P＜0.01）。30：70CCA组DM与OM进食量极显著低于其它日粮组（P＜0.01），30：70CCA组能量进食量显著低于其它日粮组，30：70CW组DM、OM在瘤胃消化率（P＜0.05）及全肠道消化率均（P＜0.01）显著低于其它日粮组：NDF、ADF瘤胃及全肠道消化率均无显著差异（P＜0.05）。30：70CCA日粮组采食时间及咀嚼时间显著高于其它日粮组（P＜0.01）；65：35CCA组采食时间、反刍时间及咀嚼时间显著低于其它日粮组（P＜0.01）。peNDF日采食量范围为3.02-6.27kg（以DM计）），peNDF占日粮干物质的17.71％-37.32％。 不同日粮精粗比对各种脂肪酸进食量有显著影响（P＜0.01），30：70CCA日粮组的油酸(C_18：1)瘤胃氢化率最低（P＜0.01）：顺式油酸(cis-C_18：1)在30：70CW及30：70CCA日粮条件下显著低于50：50CCA组和65：35CCA组（P＜0.01）。亚油酸(C_18：2)、亚麻酸(C_18：3)及不饱和十八碳脂肪酸总和(Total C₁₈UFA)的氢化率在各种日粮条件下均无显著差异（P＞0.05）。65：35CCA日粮组乳中豆蔻油酸C_14：1的含量显著高于其它处理组（P＜0.05），棕榈酸的含量C_16：0极显著低于其它日粮组（P＜0.01），65：35CCA日粮组反式油酸trans-C_18：1的含量高于其它处理组（P＜0.10）。饱和脂肪酸（SFA）、不饱和脂肪酸（UFA）、单不饱和脂肪酸（MUFA）及多不饱和脂肪酸（PUFA）进食量、十二指肠、乳中及粪中脂肪酸百分比存在显著差异。更多还原

【Abstract】 The effects of different forage to concentrate ratio on rumen fermentation, digestion and milk production were investigated. Four ruminally and duodenally cannulated primiparous Holstein cows in mid lactation (BW: 483 21kg, DIM: 175 6d) were used in 4x4 Latin square design with 23-d each period. Diets were 30:70CW(forage was composed of Chinese wildrye,CW), 30:70CCA (forage was composed of corn silage, Chinese wildrye and alfalfa, CCA ) , 50:50CCA and 65:35CCA, respectively. Treatments had no effect (P>0.10) on degradability coefficients of feed. Efficient degradability rate of concentrate was the highest, Chinese wildrye was lowest (P<0.01). Degradability of alfalfa at 12h(P<0.05) and corn silage at 12h(P<0.10) were the lower in Diets with 30:70CW, degradability of Chinese wildrye at 4-24h was lower in 65-.35CCA diet (P<0.10) .Rumen pH value in 4-6h was lower than 6.1 and cellulose enzyme activity trended to decrease in 30:70CCA. Rumen pH value and ammonia nitrogen concentration (P<0.05) increased with decreasing forage level. Acetate concentration tended to be higher in 30:70CW (P=0.10), acetate to propionate ratio and butyrate in rumen were significantly different (P<0.01). Milk fat percentage, milk yield, milk protein percentage, and solid non-fat (SNF) were significant difference (P<0.01). DM, OM and energy intakes were lower in 30:70CCA (P<0.05) than the other treatments, Energy intake for cows fed 30:70CW was lower than for the other diets (P<0.01). Ruminal and total tract digestibility of DM, OM and Energy was lower for cows fed 30:70CW diets than the other diets (PO.05). No differences were detected (P>0.10) in digestibility of NDF and ADF. Eating time and chewing time in 30:70CCA were longer than other diets (P<0.01); 65:35CCA had decreased eating time, ruminanting, chewing time (P<0.01) and Chewing time unit DM/NDF per day (P<0.05). Range of peNDF intake was 17.71% to 37.32% of DM.Fatty acid intakes were significantly different in the treatments (P<0.01). Flow of trans-C18:1 to the duodenum was higher 65:35CCA (P<0.10) than other diets. Biohydrogenation rate of C18:1 in rumen reduced dramatically in cows fed 30:70 CCA diets (P<0.01). The Cows fed 30:70(CW and CCA) diets had lower extent of biohydrogenation cis-C18:1 compared with 50:50CCA and 65:35CCA (PO.01). Biohydrogenation rate C18:2, C18: 3 and total unsaturated C18 FA was not affected by treatment (P>0.05). Biohydrogenation rate of cis-C18:1 was lower compared with C18:2, C18:3. The concentration of C14:1(P<0.05), trans-C18:1 (P<0.10) FA in milk was higher for cows fed 65:35CCA diet. C,6:0 concentration was lower for cows fed 65:35CCA than the other diets. Percentage of saturated fatty acids and unsaturated (mono/poly unsaturated) fatty acids were different among feed, duodenal digesta, feces and milk.更多还原