【作者】 石风华；

【导师】 孟庆翔；

【作者基本信息】 中国农业大学 ， 动物营养与饲料科学， 2014， 博士

【摘要】 本论文通过活体外产气量试验,尼龙袋试验,饲养试验,消化试验和屠宰试验,系统地研究了非常规饲料(NCF)部分或全部替代玉米对肉牛瘤胃发酵特性、瘤胃降解率、生产性能、养分消化率和胴体品质的影响。试验1：采用化学分析法测定了啤酒糟、豆腐渣、落地枣、糖蜜、大豆皮等NCF的营养成分,利用NRC和INRA模型计算了NCF的能量价值。结果表明,啤酒糟和豆腐渣的CP、NDF、ADF含量高于玉米,但是淀粉含量低于玉米；落地枣的CP含量虽然低于玉米,但是其NDF、ADF和糖分却相对较高；与落地枣相似,糖蜜也含有较高的可溶性糖含量和更高的CP含量,但其NDF和ADF含量很低；大豆皮的CP含量与玉米类似,但其ADF和NDF含量较高。另外,这些非常规饲料的能量含量如TDN、DE、ME、NEm, NEg等均低于玉米。小结：啤酒糟、豆腐渣、糖蜜、落地枣和大豆皮等具有较高的营养价值,可以作为玉米等粮食类饲料的替代物饲喂反刍动物。试验2：目的是用体外产气量技术评价以非常规饲料为基础的肉牛日粮营养价值。日粮包括传统日粮组(TD,45.0%玉米),部分替代日粮组(PRD,15.0%玉米,67%NCF)和全部替代组(TRD,0%玉米,100%NCF)。结果表明,与传统日粮(TD)组相比,用NCF以30%比例替代玉米(PRD)组和用NCF全部替代玉米的(TRD)组淀粉含量较低,但糖、NDF和ADF含量较高。TRD组96h累积产气量(P=0.002),理论最大产气量(P=0.001)和产气速率(P<0.001)显著低于TD组和PRD组。三个日粮组的气体成分中,氢气含量差异不显著。PRD日粮组甲烷和二氧化碳含量显著低于(P<0.01)其他两组,但另外两组之间差异不显著(P>0.05)。三个日粮组pH值、氨态氮和总挥发性脂肪酸含量均无显著差异(P>0.05)。三个日粮组乙酸,丁酸和戊酸含量差异显著(P<0.01),其中TD组乙酸和戊酸含量最低,丁酸含量最高,而TRD组的乙酸和戊酸含量最高,丁酸含量最低,PRD组居中。TD组乙酸和丙酸比显著低于(P<0.01)PRD和TRD组,而PRD和TRD组之间差异不显著(P>0.05)。TRD组的有机物消化率显著低于其他两组(P<0.01)。小结：用部分NCF替代玉米(PRD组)对日粮的营养价值(化学组成,产气参数和有机物消化率等)没有显著影响,但是用NCF全部替代玉米则降低日粮的营养价值。试验3：目的是用尼龙袋法评价以NCF为基础的肉牛日粮在瘤胃的降解率及降解参数。试验结果表明,TD组干物质快速降解成分(a)显著低于(P<0.05),而慢速降解部分(b)则显著高于(P<0.05)其他两组,但其他两组之间差异不显著(P>0.05)。PRD组和TRD组干物质有效降解率显著高于TD组。TD组蛋白质快速降解成分(a)显著高于PRD组和TRD组,慢速降解成分(b)显著低于PRD组和TRD组。TD组蛋白质降解速率(c)和有效降解率均显著低于其他两组(P<0.05)。三个日粮组NDF快速降解成分(a)无显著差异(P<0.05),但PRD组的NDF慢速降解成分(b)显著低于TD组和TRD组。三个日粮组的降解速率(c)和有效降解率均无显著差异(P>0.05)。小结：非常规饲料替代玉米提高了日粮的干物质及蛋白质的有效降解率,但没有改变NDF的有效降解率。试验4：目的是研究以NCF替代玉米对肉牛生长性能、血液参数和经济指标的影响。选用45头利木赞和鲁西杂交牛进行91d饲养试验,饲粮处理同试验2。结果表明,PRD和TRD组的末期体重与TD均无显著差异(P>0.05)。TD、PRD和TRD组ADG和DMI分别为1.72和8.66kg/d,1.60和9.10kg/d,及1.40和9.11kg/d。TRD组的日增重显著低于TD组(P<0.01),而PRD组与TD组无显著差异(P>0.05)。PRD组与TRD组的绝对采食量(kg)显著(P<0.01)高于对照组,但三个日粮组的相对采食量(占体重%)无显著差异(P>0.05)。TRD组饲料转化效率(G/F)与PRD组无显著差异(P>0.05),但显著低于TD组(P<0.01),即全部替代组的饲料转化效率最低。PRD组饲料转化效率(G/F)与TD组无显著差异(P>0.05),但有降低趋势。PRD和TRD组的血液尿素氮(BUN)和尿素的含量虽显著高于(P<0.01)对照组,但均处于正常水平,其他指标与对照组均无显著差异(P>0.05)。TD、PRD和TRD组每头牛每天饲料成本分别为9.70元、6.38元和4.69元,每千克增重的饲料成本分别为5.79元、4.10元和3.52元,且PRD和TRD组显著低于(P<0.01)TD组。投入产出分析结果表明,TRD组显著高于(P<0.01)TD组,而PRD组则显著高于(P<0.01)TRD组。小结：虽然传统日粮组牛增重速度最快,但是部分替代组和全部替代组的经济效益更好。在我国,用部分非常规饲料替代粮食饲喂肉牛可能具有较大的经济竞争力。试验5：用全收粪法研究NCF替代玉米对肉牛养分消化率和粪便颗粒分布的影响。试验结果表明,各日粮组之间的干物质采食量差异不显著(P>0.05),但TD组粪便干物质排出量显著低于(P<0.01)PRD组和TRD组。用NCF替代玉米显著降低了(P<0.018)有机物(OM)消化率,但对DM、CP、NDF和ADF消化率没有显著影响(P>0.5)。用NCF部分或全部替代玉米后,肉牛粪便中大颗粒度比例提高,尤其是TRD和PRD组6mm-4mm和4mm-2mm间颗粒度比例显著高于TD组(P<0.01)。小结：用非常规饲料替代肉牛饲粮中玉米后降低了日粮有机物消化率,但对蛋白和纤维组分消化率未见显著影响。试验6：旨在研究用非常规饲料替代玉米饲喂肉牛对其屠宰性能、胴体指标和牛肉品质的影响。饲养试验结束后从每处理组随机挑选8头牛屠宰,测定其屠宰性能、胴体指标和牛肉品质。结果表明,三个日粮处理组间屠宰率、净肉率、眼肌面积、背膘厚、大理石纹、肉pH值、剪切力、蒸煮损失、滴水损失、肉色,牛肉水分、蛋白、脂肪、灰分等各项指标均无显著差异(P>0.05)。小结：用非常规饲料部分或全部替代玉米饲喂肉牛,对其屠宰性能、胴体指标和牛肉品质未见不良影响。更多还原

【Abstract】 The present study was conducted to investigate the effect of paitial or total replacement of maize grains with non-conventional feedstuffs (NCF) on rumen fermentation characteristics, rumen degradation rate, growth performance, nutrient digestion and carcass quality of beef cattle using in vitro gas production, in situ nylon bag technique, total collection digestion trial, and feeding-slaughtering trial.Expt.1. This study was conducted using chemical analysis and model predictions based on NRC and INRA models to compare the chemical compositins and energetic values of some NCF sources including brewer’s grains, tofu residue, Chinese jujube, and molasses. The results showed that contents of CP, NDF, ADF of brewer’s grains and tofu residue were higher than those of maize grains, but the content of starch was lower than that of maize grains. Although the CP content of Chinese jujube was lower than maize grains, their NDF, ADF and sugar were relatively high. Similar to Chines jujube, molasses contained higher sugar and slightly higher CP contents, but had lower NDF and ADF content than jujube. Soybean hulls had the content of CP similar to maize grains, but haigher contents of ADF and NDF than maize grains. In addition, the energetic contents of these NCF such as TDN, DE, ME, NEm, NEg were lower than maize grains. In summary, brewer’s grains, tofu residue, molasses, soybean hulls and Chines jujube due to their high nutritional values, would be used as alternative feeds for substitution of maize grains to feed ruminant animals.Expt.2. This study was conducted to evaluate the nutritive value of NCF-based diets in cattle using in vitro gas production (GP) technique. Three dietary treatments used as substrates were typical diet (TD;45.0%maize), partial replacement diet (PRD;15%maize,67%NCF) and total replacement diet (TRD;0%maize,100%NCF), respectively. The results showed that compared with TD, PRD and TRD had much lower starch content, but higher sugar, ADF and NDF contents. TRD showed a lower96h accumulative GP (P=0.002), potential GP (P=0.001) and GP rate (P<0.001) than TD and PRD, while the PRD was not significantly different from TD (P>0.05). H2percentage was not different among the three treatment diets. The contents of CH4and CO2for PRD were significantly lower than TD and TRD. There were no significant differences in pH among the three diets. Ammonia-N (mg/100ml) and total VFA (mmol/L) did not differ among the three diets. There were lowest acetate and valerate and highest butyrate for TD and there were highest acetate and valerate and lowest butyrate for TRD. Acetate to propionate ratios were significantly lower (p<0.01) for TD than PRD and TRD, whereas PRD and TRD were not significantly different (p>0.05). The digestibilities of organic matter (OMD) were significantly higher (P<0.01) for TD and PRD than TRD, while there were no difference (P>0.05) between TD and PRD. In conclusion, the nutritive values expressed with chemical compositions, gas production characteristics and organic matter digestibility were similar for partial replacement diets to typical diets, while totally replacement diet had lower nutritive values.Expt.3. This study was conducted to evaluate the degradation rate and degradation parameters of three NCF-based diets using the nylon bag method. Dietary treatments are the same as Expt.2. The results showed that the rapid degradation fraction (a) of dry matter of TD was significantly lower (P <0.05), while the slow degradation fraction (b) was significantly higher than (P<0.05) the other two diets. The effective degradation (ED) of DM of PRD and TRD was significantly higher than TD. The value "a" of CP was significantly higher (P<0.05) for TD than PRD and TRD, but the value "b" of CP was significantly lower (P<0.05) for TD than PRD and TRD. The value "c" and ED of CP was significantly lower for TD than the other two diets (P<0.05). The value a, c and ED of NDF were not significantly different (P>0.05) among three diets, but the b fraction of NDF was significantly lower for PRD than TD and TRD. hi conclusion, partial or total replacement of maize grains with NCF would improve the ruminal degradation of DM and CP, but not affect the degradation of NDF.Expt.4. This study was conducted using direct collection feces method to investigate the effects of partial or total replacement of maize grains with NCF on growth performance, blood metabolites, and ecnomics in Limousin crossbred feedlot cattle. Forty-five Limsin x Luxi crossbred bulls were used in a9Id-feeding trail. Dietary treatments were the same as Expt.2. The results showed that final body weights were not significantly different between groups (P>0.05). ADG and DMI were1.72and8.66,1.60and9.10, and1.40and9.11kg/d for TD, PRD and TRD, respectively. PRD and TRD exhibited lower ADG (P<0.01) and higher DMI (P<0.01) than TD. DMI (%of body weight) was not significantly different between groups (P>0.5). Feed efficiency (G/F) of PRD and TRD were lower than TD (P<0.01). Blood urea nitrogen (mg/dl) in PRD and TRD was higher than TD (P<0.01), while other blood parameters did not differ significantly. Feed costs (yuan/head/d) were9.70,6.38and4.69yuan for TD, PRD and TRD, respectively (P<0.01). Feed costs per kg gain (yuan) for PRD (4.10) and TRD (3.52) were significantly lower than TD (5.79; P<0.01). The out/input of TRD were significantly higher than TD, while P RD were significantly higher than TRD. In conclusion, while a traditional diet maximized the growth rate, partial or total replacement of maize grains with NCF proved economically acceptable due to lower costs. Partial replacement may prove economically competitive in China.Expt.5. This study was designed to study the impact of NCF substitution for maize grains on nutrient digestibility and fecal particle distribution of beef cattle. The results showed that dry matter intake of each group was not significant (P>0.05), but fecal DM excretion was significantly lower (P <0.01) for TD than PRD and TRD. The replacement of maize grains with NCF significantly (P<0.018) reduced OM digestibility, but not significantly affect digestibilities of DM, CP, NDF and ADF (P>0.05). After paitial or total replacement of maize grains with NCF, TRD and PRD had significantly higher large particle distributions in the manure than TD (P<0.01), especially the6mm-4mm and4mm-2mm section. In summary, using NCF inst ead of maize grains in the growing cattle diet reduced OM digestility, but did not significantly reduce the digestibilities of other nutrients.Expt.6. This study was conducted to study the effects of partial or total replacement of maize grains with NCF on slaughtering performance, carcass traits and beef quality. After the feeding trial,8cattle were randomly selected from each group to measure the slaughtering performance, carcass traints and beef quality. The results showed that dressing percentage, net meat percentage, bones:muscles, fat thickness, ribeye area, marbling score, yield index, shear force, cooking loss, drip loss, pH value, meat colour, meatm moisture, protein, fat and ash were not significantly different (P>0.05) among the three dietary groups, suggesting that using NCF for replacement of maize grains in the diet would not affect the slaughtering performance, carcass traits and beef quality.更多还原