【作者】 高翔；

【导师】 王虎成； 冯强；

【作者基本信息】 兰州大学 ， 农业·畜牧（专业学位）， 2023， 硕士

【摘要】 随着草牧业高质量发展,家畜全混合日粮(Total Mixed Rations,TMR)形式多种多样。全混合发酵饲粮(Fermented total mixed rations,FTMR)是将青贮发酵与TMR生产技术相结合而生产的新型饲料,因其具有使用便捷等诸多优点而倍受关注。本研究基于试验区资源禀赋与生产实际,调制以玉米秸秆黄贮为主要粗饲料源的肉羊育肥期青贮型FTMR,并以未发酵的青贮型TMR为对照,开展饲粮营养品质及肉羊饲喂效果系列研究,旨在为肉羊青贮型FTMR的调制及推广应用提供理论与技术支持。将12只生长期小尾寒羊公羔(25.58±3.36 kg)依饲喂饲粮不同分为2组,即青贮型TMR(CON组)与青贮型FTMR(FTMR组)。饲养试验共计105 d,其中过渡期15 d,正试期90 d。研究结果表明:1.相较于CON,FTMR的中性洗涤纤维(Neutral detergent fiber,NDF)与酸性洗涤纤维(Acid detergent fiber,ADF)含量均较低(P<0.001),而粗蛋白(Crude protein,CP)含量(P=0.002)、相对饲用价值(Relative feeding value,RFV)(P<0.001)、总可消化养分(Total digestible nutrients,TDN)(P<0.001)较高。康奈尔净碳水化合物蛋白质体系(Cornell net carbohydrate protein system,CNCPS)评价指标结果显示,非蛋白氮、快速、中速降解蛋白以及结合蛋白组分未受到发酵处理显著影响(P>0.05),而FTMR的中性不溶蛋白含量较低(P=0.004),可溶性蛋白含量较高(P=0.013),增幅达到18.92%;慢速降解蛋白较低(P=0.003);FTMR组乙酸、丙酸以及乳酸含量较高(P<0.001),而丁酸含量较低(P<0.001),p H下降幅度达2.6%(P=0.001)。2.FTMR组试羊干物质采食量较CON组低(P=0.012),而饲料转化效率较高(P=0.010);两组间末体重与日增重均无显著差异(P>0.05);FTMR组CP和ADF消化率较高(P<0.001);瘤胃p H、氨态氮、丙酸及乙丙比两组间无显著差异(P>0.05),但CON组的总挥发性脂肪酸(Total volatile fatty acids,TVFA)浓度(P=0.004)和丁酸(P=0.003)比例高于FTMR组。此外,CON组甲烷与粪氮排出量均高于FTMR组。3.FTMR组试羊的宰前活重(42.72 kg vs.40.91 kg)、胴体重(20.47 kg vs.20.01 kg)、背膘厚(6.33 mm vs.5.84 mm)略高于CON组(P>0.05),而屠宰率(47.89%vs.48.90%)与眼肌面积(13.55 cm~2 vs.17.17 cm~2)则略低于CON组(P>0.05)。FTMR组三级肉比例低于CON组(P=0.009),一级肉比例较CON组高,增幅达13.31%。两组羊肉营养组分中水分、粗蛋白、粗脂肪均无显著差异(P>0.005)。两组间p H、肉色、熟肉率均无显著差异(P>0.005)。CON组中α-亚麻酸(C18:3n3,P=0.033)以及亚油酸(C18:2n6c,P=0.001)含量均显著高于FTMR组,而反式亚油酸(C18:2n6t)含量则在FTMR组较高(P=0.011);CON组肉豆蔻酸(C14:0,P=0.053)以及肉豆蔻烯酸(C14:1n9c,P=0.058)含量则略高于FTMR组。羊肉脂肪酸营养价值指标中,FTMR致动脉粥样硬化指数(0.51 vs.0.52)、血栓形成指数(0.54 vs.0.56)、Δ6+Δ5去饱和酶活性(0.32vs.0.27)以及过氧化性指数(4.51 vs.5.38)均较优于CON组;且在冷藏储存期间CON组羊肉脂质氧化程度强于FTMR;通过对比两组经济效益,FTMR组各项成本均低于CON组,IOFC(Income over feeding cost)增幅达28.81%。综上,相较于未发酵的TMR,发酵可显著降低饲粮中NDF、ADF以及慢速降解白蛋白含量,提高CP以及快速降解蛋白含量,通过营养成分与发酵质量多方面提升饲喂价值,并且显著改善了育肥肉羊饲料转化效率与纤维组分表观养分消化率,在一定程度上具有减缓肉羊脂质氧化程度,提高养殖效益的应用潜力。更多还原

【Abstract】 With the development of high-quality grass grazing,there are various forms of total mixed rations(TMR)for livestock.Fermented total mixed rations(FTMR)is a new type of feed produced by combining silage fermentation with TMR production technology,and has attracted more attention because of its many advantages such as ease of use.In this study,a series of studies on the nutritional quality and feeding effect of FTMR for sheep were conducted in the experimental area based on the resource endowment and production practice,with maize straw silage as the main roughage source and unfermented silage as the control.Twelve thin-tailed Han sheep(25.58±3.36 kg)were divided into 2 groups according to the diets:silage-type TMR(CON)and silage-type FTMR(FTMR).The feeding experiment lasted for 105 days,with a transition period of 15 days and a trial period of 90 days.The results of the study were as follow:1.Compared to CON,FTMR had a lower neutral detergent fiber(NDF)and acid detergent fiber(ADF)content(P<0.001),while the crude protein(CP)content(P=0.002),relative feeding value(RFV,P<0.001)and total digestible nutrients(TDN,P<0.001)were higher than in the unfermented TMR.The results of the Cornell Net Carbohydrate Protein System(CNCPS)evaluation indexes showed that non-protein nitrogen,rapidly and moderately degraded protein and bound protein fractions were unaffected by the fermentation treatment(P>0.05),while the FTMR had a lower neutral insoluble protein content(P=0.004)and a higher soluble protein content(P=0.013)with an increase of 18.92%,and a lower slow degraded protein(P=0.003).The FTMR group had higher proportion of acetate,propionate and lactate(P<0.001)and lower proportion of butyrate(P<0.001),with a 2.6%decrease in p H(P=0.001).2.The dry matter intake(DMI)was lower in the FTMR group compared to the CON group(P=0.012),while feed conversion efficiency was higher(P=0.010).No differences were found in final body weight and daily gain between the two groups(P>0.05).The CP and ADF digestibility were higher in the FTMR group(P<0.001).The ruminal p H,ammonia nitrogen,the proportion of propionate and the ratio of acetate to propionate were similar between the two groups(P>0.05).However,the concentration of total volatile fatty acids(TVFA,P=0.004)and proportion of butyrate(P=0.003)were higher in the CON group than in the FTMR group.In addition,both methane and fecal nitrogen excretion were higher in the CON group than in the FTMR group.3.The FTMR group had a slightly higher live weight before slaughter(42.72 kg vs.40.91 kg),carcass weight(20.47 kg vs.20.01 kg)and backfat thickness(6.33 mm vs.5.84 mm)than the CON group(P>0.05),while the slaughter rate(47.89%vs.48.90%)and eye muscle area(13.55 cm~2 vs.17.17 cm~2)were lower(P>0.05).The proportion of tertiary meat was lower in the FTMR group than in the CON group(P=0.009),while the proportion of primary meat was increased by 13.31%compared to the CON group.There was no difference in moisture,crude protein(CP)and ether extract(EE)in the nutritional fractions of lamb between the two groups(P>0.005).There were no differences in p H,meat color and percentage of cooked meat between the two groups(P>0.005).The contents ofα-linolenic acid(C18:3n3,P=0.033)and linoleic acid(C18:2n6c,P=0.001)were higher in the CON group than in the FTMR group,while the content of trans linoleic acid(C18:2n6t,P=0.011)is higher in the FTMR group.The content of Myristic acid(C14:0,P=0.053)and myristic acid(C14:1n9c,P=0.058)in the CON group was slightly higher than in the FTMR group.In terms of fatty acid nutritional value of lamb,the atherogenic index(0.51 vs.0.52),thrombogenic index(0.54 vs.0.56),Δ6+Δ5 desaturase activity(0.32 vs.0.27)and peroxidability index(4.51 vs.5.38)were better in the FTMR than in the CON.During refrigeration,the degree of lipid oxidation in the CON group was stronger than that in the FTMR group.Comparing the economic benefits of the two groups,the FTMR group had lower costs than the CON group,and the IOFC(Income over feeding cost)increased by28.81%.In summary,compared to unfermented TMR,fermentation significantly reduced the NDF,ADF and slow degrading protein content and increased the CP and fast degrading protein content in the ration,improving the feeding value in terms of nutrient composition and fermentation quality,and significantly improving the feed conversion efficiency and apparent nutrient digestibility of fiber fractions in fattening sheep,with the potential to slow down lipid oxidation in sheep and improve farming efficiency to a certain extent.更多还原