直接法和回归法测定玉米青贮对肉牛有效能值的研究

旨在应用直接法和回归法测定肉牛玉米青贮的消化能、代谢能和净能值,并探讨精料回归法用于估测肉牛单一粗饲料原料能值的可行性。试验选取12头体况良好、体重相近[(259±14.08)kg]的生长期公牛,随机分为3组,每组4头牛。分两期试验进行,试验一按试验牛自由采食量的95%、80%和60%3个水平饲喂全玉米青贮日粮;试验二在固定玉米青贮投喂量的基础上,各组分别按青贮饲喂量的15%、25%和50%(干物质基础)添加精料补充料。试验每期14d,其中前10d为预饲期,后4d为正试期。正试期消化代谢和呼吸代谢试验同期进行,测定玉米青贮对肉牛能量代谢规律。结果表明:1)肉牛对全玉米青贮日粮的各种营养物质消化率和能量消化率及代谢率随饲喂水平的提高总体逐渐降低;肉牛能量采食量(总能、消化能、代谢能和净能)随饲喂水平的提高逐渐升高,组间差异显著(P0.05)。2)玉米青贮对肉牛的消化能、代谢能和净能值随着饲喂水平的提高呈下降趋势,各有效能值变化范围分别为10.58~11.48 MJ/kg,8.33~9.44 MJ/kg和5.20~6.21 MJ/kg。3)添加精料补充料显著提高了肉牛对日粮的干物质采食量和粗蛋白消化率(P0.05),而洗涤纤维消化率精料添加比例组间差异不明显(P0.05);随着精料添加比例的增加,肉牛对日粮的能量采食量(总能、消化能、代谢能和净能)和能量消化率及代谢率逐渐上升,消化能代谢率各组之间无显著差异(P0.05)。4)根据试验日粮有效能值与精料添加量之间的关系建立线性回归方程后,外推估测得玉米青贮的消化能、代谢能和净能值分别为10.53 MJ/kg、8.29 MJ/kg和5.35MJ/kg,与95%饲喂水平组直接测定结果(10.58 MJ/kg、8.33 MJ/kg和5.20 MJ/kg)差异不显著(P0.05)。综上所述,回归法测定玉米青贮对肉牛的有效能值与直接法测定结果差异不明显,精料回归法可以用于估测肉牛单一粗饲料的有效能值。     

日粮中不同粗饲料组合对南方肉牛生长性能及血清生化指标的影响

[目的]旨在探讨不同粗饲料组合对肉牛生长性能、干物质消化率及血清生化指标的影响,从而为肉牛育肥过程中合理使用粗饲料提供依据。[方法]试验采用完全随机化设计,将28头平均1.5岁、体重相近(319.86±37.46)kg的健康利木赞×安格斯×西门塔尔三杂公牛随机分为4组,每组7头。对照组粗料饲喂全株青贮(100%),试验I组粗料饲喂青贮玉米(40%)和黄贮玉米(60%),试验II组粗料饲喂青贮玉米(40%)和象草(60%),试验Ⅲ组粗料饲喂黄贮玉米(40%)和象草(60%),精料均为5kg/头·天,试验期每周按头测定一次精料和粗料采食量,全部试验牛栓系饲养并自由饮水。试验期70天,预饲期5天,正试期65天,试验前后空腹称重,记录初重和末重并计算日增重、料重比和经济效益等指标;试验结束前四天,用全收粪法测定干物质消化率;最后一天空腹采集血样测定血清指标。[结果]试验I组的平均日增重最高,为1.198kg/d,试验Ⅲ组最低,为1.106kg/d,但各组之间差异不显著(P0.05);干物质采食量以试验I组最高,显著高于对照组(P0.05),但与其它两组差异不显著;粗料采食量各组间无差异,但精料采食量以对照组为最低,试验Ⅲ组最高(P0.01);对照组干物质消化率显著高于其它三个试验组(P0.05),以试验Ⅲ组为最低。料重比以试验Ⅲ组最高,对照组最低,但各组之间差异不显著(P0.05);经济效益以试验I组最高,但各组差异不显著(P0.05)。血液生化指标除血清中尿素氮水平试验I组显著低于对照组外(P0.05),其它各血液指标均差异不显著(P0.05)。[结论]全株青贮玉米作为育肥期肉牛的优质粗饲料,本研究表明其与黄贮玉米组合后相比单独饲喂全株青贮或低质的黄贮玉米与象草组合,提高了肉牛采食量、日增重、饲料转化效率及经济效益,发挥了粗饲料间的组合效应并对精料和粗料的组合效应有促进作用,对南方低质粗饲料的合理利用具有指导意义。     

差额法和粪氮指数法对估测放牧绵羊采食量的影响研究

为评价放牧绵羊采食量,采用控制放牧试验,设置5个放牧处理,比较了差额法和粪氮指数法测定放牧绵羊采食量的结果。结果表明:绵羊采食量随放牧强度的增大而减小,春季休牧能显著提高绵羊的采食量(P <0.05)。其中用差额法测定的最高采食量为34.8 g·d^-1·kg^-1,粪氮指数法测得的最高采食量为46.4 g·d^-1kg^-1。2种测定方法测定结果具有相同的趋势,粪氮指数法的测定结果显著高于差额法(P <0.05)。差额法测定的采食量和粪氮指数法测定的采食量间成指数相关,方程为y=1.1577e^0.0628x(R²=0.677)。     

不同精粗比饲粮中添加凝结芽孢杆菌对绵羊羔羊生长性能和消化代谢的影响

本试验旨在研究不同精粗比条件下饲粮添加凝结芽孢杆菌(BC)对绵羊羔羊生长性能和消化代谢的影响。试验采用2×2因子完全随机设计,2个因素分别为精粗比[40∶60(低精料)、70∶30(高精料)]和BC[不添加和添加1.0×1010CFU/kg BC]。选取48只4月龄的杜泊×小尾寒羊F1代公羔,按体重随机分为4个组,分别饲喂低精料饲粮(LD组)、添加BC低精料饲粮(LD+BC组)、高精料饲粮(HD组)、添加BC高精料饲粮(HD+BC组),每组12只。生长性能试验共计70 d,其中预试期10 d,正试期60 d;消化代谢试验共计7 d,其中适应期4 d,取样期3 d。结果显示：1)24只饲喂高精料饲粮羔羊的末重(FBW)和平均日增重(ADG)显著或极显著高于24只饲喂低精料饲粮羔羊(P<0.05或P<0.01),并且料重比(F/G)极显著低于24只饲喂低精料饲粮羔羊(P<0.01);24只饲喂添加BC饲粮羔羊的ADG显著高于24只饲喂不添加BC饲粮羔羊(P<0.05)。2)24只饲喂高精料饲粮羔羊对干物质(DM)、有机物(OM)、中性洗涤纤维(NDF)的表观消化率极...     

断奶期内不同饲粮对羔羊生长、营养物质表观消化率和瘤胃发酵参数的影响

本试验旨在研究断奶期内不同饲粮对羔羊生长、营养物质表观消化率和瘤胃发酵参数的影响。选取48只健康、体重相近的45日龄湖羊羔羊（公母各占1/2）,所有羔羊在45～59日龄随母哺乳,并补饲羔羊精料补充料,在52日龄时,将公母羔羊分别按体重（15.58±2.45） kg随机分为3组,然后公母进行随机配对,每组共16个重复,公羔8只,母羔8只。在60～75日龄,试验1组随母哺乳+补饲羔羊精料补充料,试验2组在60日龄断奶,并饲喂全混合日粮（TMR）,试验3组在60日龄断奶,并饲喂50%TMR+50%羔羊精料补充料。羔羊59日龄记为试验第0天。试验期23 d。所有羔羊在试验第-7(52日龄)、0、7、15天于晨饲前称重,并记录每天采食量;在试验第0、3、9和15天于晨饲前采集瘤胃液,测定瘤胃发酵参数。羔羊在试验第-7、3、9、15天进行消化代谢试验,测定营养物质表观消化率。结果表明：1）在试验第0～7天,试验1组羔羊平均日增重（ADG）比试验2组显著提高了87.93%(P<0.05);试验3组羔羊干物质采食量（DMI）比试验1组显著提高了17.03%(P<0.05);试验1、3组粗蛋...     

精料比例对皖南牛粗饲料采食量和日粮养分表观消化率的影响

本试验研究精料比例对皖南牛粗饲料采食量和营养物质表观消化率的影响。30头去势的体重相近的18月龄皖南牛,随机分成5组,各组根据体重的1.9%、1.6%、1.3%、1.0%和0.7%补充精料,通过饲养试验和消化试验测定粗饲料采食量和日粮养分表观消化率。结果表明:皖南牛的粗饲料采食量随着精料饲喂量的减少而增加,总的干物质采食量(DMI)随着精料饲喂量的减少而降低;日粮的干物质(DM)、有机物(OM)、粗蛋白(CP)、粗脂肪(EE)和总能(GE)的表观消化率随着精料饲喂量的减少而降低;日粮中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的表观消化率随着精料的减少先升后降,精料饲喂量占体重1.0%的组的NDF和ADF表观消化率最高,分别为60.48%和57.07%。     

饲喂苎麻嫩茎叶青贮料对山羊育肥效果及肌肉品质的影响

为研究苎麻嫩茎叶青贮饲料对波尔山羊羊肉品质以及育肥效果的影响,试验选取波尔山羊公羊50只,随机分为2组,每组25只,进行饲喂试验。在同等精料水平下,试验组和对照组分别以苎麻嫩茎叶青贮和苜蓿干草为粗料,并与精料混合成全混合日粮,干物质粗精比为4555。每日观察试验羊健康状况,并在饲喂结束后统计采食量、日增重,检测肌肉中氨基酸、脂肪酸成分与含量。结果表明:苎麻嫩茎叶青贮料添加到全混合日粮中,波尔山羊能正常采食,适口性较好。相对于苜蓿干草,饲喂苎麻嫩茎叶青贮对波尔山羊增重效果明显,并且能降低硬脂酸和增加鲜味氨基酸含量,有助于提升羊肉品质。     

日粮精粗比对延边黄牛养分表观消化率和尿嘌呤衍生物排出量的影响

试验旨在采用日粮调控来探究不同精粗比的日粮对育肥前期的延边黄牛养分表观消化率及尿嘌呤衍生物排出量的影响。选择4头年龄及体质量相近(300±15)kg的延边黄牛,采用4×4拉丁方设计,分别饲喂精粗比为30∶70、40∶60、60∶40和70∶30的育肥前期基础日粮。试验分为4个阶段,每阶段20 d,预试期15 d,正试期5 d收集样品。结果表明:干物质、有机物和粗蛋白采食量随着日粮精料水平的提高而线性增加(P0.01),而中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)采食量随日粮精料水平的提高而线性降低(P0.01);随着精粗比的提高,干物质表观消化率显著升高(P0.05),粗蛋白表观消化率显著降低(P0.05)。有机物及酸性洗涤纤维表观消化率随着日粮精料水平的提高差异不显著(P0.05);总嘌呤衍生物排出量和尿囊素随着精粗比的提高呈升高的趋势(P0.05或P0.01)。由此可知,提高日粮精料比例能增加试验牛干物质、有机物和粗蛋白采食量,中性洗涤纤维和酸性洗涤纤维采食量则相应减少;并且有效的提高干物质表观消化率和瘤胃可利用氮含量。     

精料补充料在家兔日粮中的应用研究

选择35日龄左右、健康无病的齐卡大型白兔120只,随机分为4组,分别饲喂全价饲料和3种不同营养水平的精料补充料,观察其采食量、日增重和成活率。结果表明:饲喂青草加精料补充料较饲喂全价饲料成本低。而精料补充料以消化能12.76MJ/kg、粗蛋白19.28%、粗纤维6.21%的营养水平饲喂效果最佳。     

不同精粗料比饲料饲喂羔羊育肥试验

试验利用饲料的不同精粗比分组,对农区集约化羊场的2月龄断奶杂交羔羊进行育肥,观察其对育肥羔羊的日增重、饲料报酬、经济效益及屠宰率和肉品质的影响,探讨合适的精、粗料比例,为农区集约化肥羔生产提供参考。1材料与方法1.1试验材料选择新疆兵团农七师129团集约化羊场的2月龄断奶、体重相近、健康无病的Romilly Hilly肉用细毛羊与中国美利奴羊杂交公羔72只,随机分成4组,每组18只。1.2育肥饲粮配比1,2,3,4组精料比例分别为100%、70%、50%、30%,饲料成分的含量以风干物质计算。精料为玉米、豆粕;粗料为苜蓿、青贮、西红柿酱渣;另外添加食盐…     

不同类型藏羊消化率与采食量的比较研究

采食量是放牧家畜生产性能的重要影响因素,在草地生态系统中起重要作用。夏季在甘南夏河分别选取不同生理类群(羔羊、1岁母羊、2岁母羊、3岁母羊、4岁母羊、羯羊和种公羊)的欧拉型、甘加型和乔科型藏羊各4只进行试验。采用二氧化钛指示剂法与粪氮指数法分别测定藏羊排粪量和牧草有机物质消化率,从而计算放牧采食量,并对特征间的相关性进行研究。结果表明:欧拉型、乔科型和甘加型藏羊的平均放牧采食量分别为1031.93、834.59和956.15 g·d^-1,乔科型藏羊放牧采食量显著(P<0.05)小于欧拉型和甘加型藏羊。3个类型藏羊的每kg代谢体重采食量和干物质采食量占体重比差异均不显著(P>0.05)。欧拉型、乔科型和甘加型藏羊对夏河天然草地牧草的平均有机物质消化率分别为50.79%、47.22%和55.58%。欧拉型、乔科型和甘加型藏羊的平均排粪量分别为561.26、484.06和466.74 g·d^-1,其中欧拉型藏羊的排粪量显著高于其他两个类型。试验在高寒地区天然草地研究不同类型藏羊的排粪量、有机物质消化率和放牧采食量,旨在为该地区放牧藏羊的科学饲养与管理提供理论依据。     

日粮类型对奶牛粪尿特性及氮排放的影响

通过研究不同类型日粮对泌乳奶牛粪尿及氮排放的影响,达到减少和控制氮排放的目的,本试验选用12头体重514 kg、年龄3～5岁的中国荷斯坦奶牛为试验动物,分为3组,分别饲喂粗料为干秸秆玉米,精粗比40∶60的A日粮、粗料为玉米青贮,精粗比分别是40∶60和60∶40的B和C日粮进行了对其粪尿特性及氮排放的试验研究。结果表明,日粮类型对奶牛粪便及尿液产生量均有一定的影响。粪便产生量结果为秸秆型A日粮>青贮型低精比B日粮>青贮型高精比C日粮。3种日粮的尿液产生量为C日粮>B日粮>A日粮。同时,日粮类型对奶牛氮平衡具有显著的影响,秸秆型日粮的乳氮、尿氮含量和氮的消化率极显著低于青贮型日粮低(P<0.01),粗料均为青贮玉米条件下,随日粮精料水平的提高,氮消化率和尿氮极显著增加(P<0.01),粪氮和乳氮增加不显著(P>0.05)。结果提示,秸秆型日粮的摄入氮主要是从粪中排出,粗料为青贮玉米时,随日粮精料水平的提高粪氮比例减少,而尿氮比例增加,粪氮和尿氮占总粪尿氮的比例基本一致。     

The effects of concentrate added to pineapple (<Emphasis Type="Italic">Ananas Comosus linn. Mer.</Emphasis>) waste silage in differing ratios to form complete diets,on digestion,excretion of urinary purine derivatives and blood metabolites in growing,male, Thai swamp buffaloes

Four, male, growing Thai swamp buffaloes (197 ± 5.3 kg and all 1 year old) were used to evaluate the effects of concentrate added to pineapple waste silage in differing ratios, to form a complete diet, studying in vivo digestion, the rate of passage, microbial protein synthesis and blood metabolites. Animals were fed ad libitum with 4 diets, using four combinations of pineapple waste silage (P) and concentrate (C), in the proportions (on a dry matter basis) of 0.8:0.2 (P80:C20), 0.6:0.4 (P60:C40), 0.4:0.6 (P40:C60) and 0.2:0.8 (P20:C80). The results showed that the intakes of dry matter (DM), organic matter (OM), nitrogen (N), the N-balance, urinary purine derivatives (PD) excretion, the ratios of allantoin to creatinine (CR), PD to CR, the plasma urea-N (PUN) and insulin increased in the animals, but the intake of neutral detergent fiber (NDF), the coefficient of whole tract, apparent digestibility of NDF, the transit time (TT) and the mean retention time (TMRT) decreased, when the proportion of concentrate in the diet increased. This study indicated that the proportion of P40:C60 in the diet produced the best efficiency of urinary PD excretion (mmol) per digestible OM intake (kg DOMI).     

Effects of feeding early‐harvested orchardgrass–perennial ryegrass mixed silage instead of heading stage harvested timothy silage on digestion and milk production in dairy cows

We evaluated the effects of replacement of heading stage harvested timothy silage with early‐harvested orchardgrass–perennial ryegrass mixed (OP) silage while maintaining or reducing concentrate input on dry matter intake (DMI), milk production, nutrient digestibility, and N balance in dairy cows. Nine multiparous Holstein cows were used in a replicated 3 × 3 Latin square design with three dietary treatments: TYL, a diet containing timothy silage where forage‐to‐concentrate ratio (FC) was 50:50; OPL, a diet containing OP silage where FC ratio was 50:50; and OPH, a diet containing OP silage where FC ratio was 60:40. We observed that an equal replacement of timothy with OP silage increased DMI, milk yield, milk protein production, and nutrient digestibility but decreased milk fat content (TYL versus OPL). We observed that replacing timothy with OP silage while reducing concentrate input increased milk fat and protein yield, nutrient digestibility, and feed efficiency and reduced urinary N loss with no effect on DMI or milk fat content (TYL versus OPH). These results show that replacing timothy with OP silage can be a good approach to improve milk production, feed efficiency, and N utilization and reduce concentrate input. However, milk fat depression should be considered when an equal substitution is performed.     

Effects of Rosmarinus officinalis L. essential oils supplementation on digestion,colostrum production of dairy ewes and lamb mortality and growth

The aim of this study was to evaluate the effect of rosemary essential oils (REO) and the forage nature on ewes' performances, immune response and lambs' growth and mortality. Forty‐eight dairy ewes (Sicilo‐Sarde) were fed oat‐hay or oat‐silage supplemented with 400 g of concentrate during pregnancy and 600 g during postpartum. The experimental concentrate contained the same mixture as the control (barley, soybean meal and mineral vitamin supplement) more 0.6 g/kg of REO. Two groups were obtained with each forage (Hay groups: H‐C and H‐REO; Silage groups: S‐C and S‐REO). REO increased the dry matter (DM) intake, the nitrogen intake and retention being higher with the silage groups (P < 0.05). REO increased solid non‐fat (P = 0.004) and fat contents of colostrum which was higher with hay (P = 0.002). REO decreased lamb mortality (P < 0.05) which averaged 21% for control groups and 6% for H‐REO, while no mortality was recorded with S‐REO. REO dietary supply improved forage intake and tended to ameliorate colostrum production; it could be a natural additive to improve ewes' performances.     

粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响

本试验旨在研究粗饲料组合对奶牛饲粮养分消化率、能量和氮的利用的影响。试验采用单因素随机区组设计,将 １６头体重、年龄、胎次相近的,处于干奶期的健康荷斯坦奶牛分为 ４组,每组 ４头。以常用的粗饲料设计 Ａ（玉米青贮 ＋玉米秸秆）、Ｂ（玉米青贮 ＋羊草）、Ｃ（玉米青贮 ＋玉米秸秆 ＋羊草）、Ｄ（玉米青贮 ＋苜蓿草 ＋羊草）４种粗饲料组合的饲粮。结果表明：饲粮Ｄ干物质、有机物和中性洗涤纤维的消化率最高,显著高于其他各饲粮（Ｐ＜０．０５）,其次为饲粮Ｂ和饲粮 Ｃ,饲粮 Ａ最低,显著低于其他各饲粮（Ｐ＜０．０５）,各饲粮的酸性洗涤纤维消化率差异不显著（Ｐ＞０．０５）。粗饲料组合显著影响饲粮摄入总能、能量消化率和能量代谢率（Ｐ＜０．０５）,饲粮 Ｄ甲烷能占摄入总能比显著低于其他 ３种饲粮（Ｐ＜０．０５）。各饲粮的粪氮、尿氮占摄入总氮比差异不显著（Ｐ＞０．０５）,饲粮 Ｄ的氮消化率显著高于饲粮 Ｂ与饲粮 Ｃ（Ｐ＜０．０５）,且饲粮 Ｂ显著高于饲粮 Ａ（Ｐ＜０．０５）;饲粮 Ｂ、饲粮 Ｄ的氮利用率显著高于饲粮 Ａ（Ｐ＜０．０５）。由此可见,玉米青贮 ＋苜蓿草 ＋羊草型饲粮的养分消化率、能量和氮的利用均优于其他各饲粮,羊草与玉米秸秆之间存在正组合效应,两者搭配使用可提高玉米秸秆的消化率,优化能量和氮的利用。     

添加乳酸菌和纤维素酶对茭白叶青贮品质的影响

为研究添加乳酸菌和纤维素酶对茭白(Zizania caclucifora)叶青贮品质的影响,试验设对照组(CK)、乳酸菌组(LAB, 乳酸菌1×10⁵ CFU·g^-1鲜草)、纤维素酶组(CEL, 纤维素酶1 g·kg^-1鲜草)和混合组(MIX, 乳酸菌1×10⁵ CFU·g^-1鲜草+纤维素酶1 g·kg^-1鲜草).桶装青贮,30 d后检测发酵品质.结果表明:添加乳酸菌和纤维素酶,可显著提高粗蛋白(CP),降低中性洗涤纤维(NDF)、酸性洗涤纤维含量(ADF);试验组pH、氨氮/总氮(NH₃-N/TN)值显著降低,乳酸含量、乳酸/乙酸值显著提高;试验组产气量、有机物消化率、氨氮和有机酸含量相比对照组显著提高.推荐使用乳酸菌(1×10⁵ CFU·g^-1鲜草)和纤维素酶(1 g·kg^-1鲜草)混合青贮茭白叶.     

The effects of protein sources supplemented with urea-treated potato pulp (PP) silage and feeding levels of the PP silage-based concentrate on feed intake, digestibility and ruminal fermentation in beef steers

Six Japanese Black (Wagyu) steers (average initial weight 467 ± 45 kg) fitted with a ruminal cannula were used in a split‐plot design experiment comprising a 3 × 3 Latin square design (whole‐plot) and a randomized block design (subplot). The whole‐plot treatments were three different feeding levels of urea‐treated potato pulp (PP) silage‐based concentrate: 1.00%, 1.75% and 2.50% of body weight (BW) (on a dry matter (DM) basis). The subplot treatments consisted of the concentrate formulated to contain either soybean meal (SBM) as a rapidly rumen‐degraded protein source or corn gluten meal (CGM) as a slowly degraded protein source. Dry matter intake tended to be lower (P = 0.071) for CGM (8.9 kg/day) than for SBM (9.4 kg/day). Protein sources had no significant effect on digestibility and in situ degradation. Ruminal ammonia nitrogen (NH₃‐N) was lower (P = 0.033) for CGM (7.5 mg/dL) than for SBM (9.5 mg/dL). Protein sources did not affect ruminal pH and the total volatile fatty acids (VFA) concentrations. The molar proportions of ruminal acetate and valerate were higher (P = 0.032) for CGM than for SBM. The maximum daily intake of the PP silage‐based concentrate expressed as a percentage of BW was approximately 1.4% of BW. Dry matter intake was higher (P = 0.046) for steers fed at 1.0% of BW of the PP silage‐based concentrate than for steers fed at 1.75% or 2.5% of BW of the concentrate. The feeding levels of the PP silage‐based concentrate had no effect on DM and nutrients digestibility, except for crude protein (CP) digestibility. CP digestibility tended to be lower (P = 0.071) for steers fed at 1.75% of BW of the PP silage‐based concentrate than for steers fed at 1.0% or 2.5% of BW of the concentrate. The feeding levels of the PP silage‐based concentrate also did not affect the in situ degradation parameter of hay and PP silage. The feeding levels of the PP silage‐based concentrate did not affect ruminal pH, NH₃‐N and total VFA concentrations. The molar proportion of acetate was highest for steers fed at 1.0% of BW of the concentrate. In conclusion, in the urea‐treated PP silage‐based concentrate, CGM seems to be more effective than SBM for stabilizing the ruminal NH₃‐N concentration and to be advantageous for fiber digestion in the rumen. The feeding levels of the PP silage‐based concentrate did not change the amount of VFA production in the rumen and the DM digestibility.     

牦牛与黑白花牛的氮平衡比较研究

接近初情期的牦牛和黑白花公牛各3头，于代谢厩中进行精料型（精粗比为4：1）和粗料型（精粗比为1：4）日粮条件下的氮平均对比试验。结果表明，不论牦牛还是黑白花牛，干物质采食量（DMI）、粪氮（FN）、尿氮（UN）和干物质消化率（DMD）均随精料含量上升而升高（P＜0．01），而进食氮（NI）的利用效率则随NI的升高而下降（P＜0．01）。在粗料型的日粮条件下，牦牛对NI的利用效率（58．2％）高于（P＜0．05）黑白花牛（49．0％），二者的DMD（45％）无差异；而在精料型的日粮条件下，NI的利用效率（22％）和DMD（64％）均不随牛种而变化（P＞0．05）。从这些结果得出结论：牦牛与黑白花牛消化道的吸收效率是一样的，在精料型日粮条件下，牦牛机体组织存留氮的能力低于黑白花牛；在粗料型日粮条件下，牦牛比黑白花牛更能有效地利用蛋白资源。