替代法估测肉牛对稻草和麦秸的有效能值

为分析替代法估测肉牛对稻草和麦秸的有效能值及适宜的替代比例,本研究选取12头体重相近(266±13.41)kg的11~12月龄皖东牛公牛,随机分为3组,每组4头牛,分3期进行饲喂试验。第1期:所有供试牛饲喂由带穗玉米青贮组成的基础饲粮,测定基础饲粮的有效能值;第2期和第3期:各组供试牛分别饲喂由稻草或麦秸按不同比例(10%、30%和60%)替代基础饲粮组成的试验饲粮。每期试验14 d,其中前10 d为预饲期,后4 d为正试期。正试期消化代谢和呼吸代谢试验同时进行,测定肉牛对各试验饲粮的能量代谢情况。结果表明,1)与基础饲粮相比,稻草或麦秸替代降低了肉牛对试验饲粮干物质(DM)、粗蛋白(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的表观消化率,且以上指标随替代比例的增加呈逐渐下降趋势。2)基础饲粮组和各替代组之间总能(GE)采食量无明显差异(P0.05),而消化能(DE)、代谢能(ME)和净能(NE)采食量随稻草或麦秸替代比例的增加而显著降低(P0.05),总能消化率、总能代谢率和消化能代谢率与稻草或麦秸替代比例呈负相关关系。3)根据不同试验饲粮的有效能值与稻草或麦秸替代比例之间的回归方程,估算得出稻草的DE、ME和NE分别为8.51、5.79和3.64 MJ·kg-1,麦秸的对应值分别为7.89、5.08和3.13 MJ·kg-1;10%、30%和60%3个替代比例中,30%替代比例所计算得稻草或麦秸有效能值的变异度最小(P0.05)。综上可知,替代比例会影响稻草和麦秸有效能值的测定结果,本研究中稻草或麦秸替代比例为30%时优于10%和60%。在估测单一粗饲料原料有效能值时,回归法和替代法结合能提高测定结果的准确度,也有助于筛选替代法最佳的替代比例。     

育肥后期锦江牛能量代谢规律及需要量的研究

本试验旨在研究育肥后期锦江去势公牛的能量代谢规律及需要量。在育肥前期不同能量水平饲喂的基础上(育肥前期5种肉牛日粮综合净能(NE_mf)依次为6.02、6.38、6.74、7.10、7.46 MJ/kg,每组10头牛,育肥116 d)继续育肥,育肥前期试验结束后,保持分组不变,挑选35头体型接近、体重(355.94±35.11) kg锦江牛继续育肥。按照中国《肉牛饲养标准》(NY/T 815-2004)中350 kg肉牛日增重1.2 kg/d所需净能的100%(A组)、106%(B组)、112%(C组)、118%(D组)、124%(E组)配制5种不同能量水平的试验日粮,5种日粮的NE_mf依次为6.21、6.58、6.95、7.33、7.70 MJ/kg。采用饲养试验和消化代谢试验测定育肥后期锦江去势公牛生长性能及能量代谢指标,并建立消化能和代谢能能量需要模型。预试期10 d,正试期128 d。结果表明:①D、E组育肥后期锦江去势公牛的总能采食量较其他组显著降低(P<0.05)。②B组肥后期锦江去势公牛能量利用效率最高,总能消化率、总能代谢率分别为90.59%和83.36%。③育肥后期锦江去势公牛日增重与消化能采食量和代谢能采食量存在高度线性正相关(R^2=0.997、R^2=0.993),其消化能、代谢能需要量的回归方程分别为:DE_m=0.770W^0.75+40.088×ADG;ME_m=0.645W^0.75+38.603×ADG(其中DE为消化能总需要量(MJ/d);ME为代谢能总需要量(MJ/d);W^0.75为单位代谢体重(kg);ADG为平均日增重(kg/d))。综上所述,育肥后期锦江牛的维持消化能总需要量(DE_m)和代谢能总需要量(ME_m)分别为0.770、0.645 MJ/(kg W^0.75·d),每千克增重的消化能和代谢能需要量分别为40.088、38.603 MJ。     

育肥后期锦江牛能量代谢规律及需要量的研究

本试验旨在研究育肥后期锦江去势公牛的能量代谢规律及需要量。在育肥前期不同能量水平饲喂的基础上(育肥前期5种肉牛日粮综合净能(NE_(mf))依次为6.02、6.38、6.74、7.10、7.46 MJ/kg,每组10头牛,育肥116 d)继续育肥,育肥前期试验结束后,保持分组不变,挑选35头体型接近、体重(355.94±35.11) kg锦江牛继续育肥。按照中国《肉牛饲养标准》(NY/T 815-2004)中350 kg肉牛日增重1.2 kg/d所需净能的100%(A组)、106%(B组)、112%(C组)、118%(D组)、124%(E组)配制5种不同能量水平的试验日粮,5种日粮的NE_(mf)依次为6.21、6.58、6.95、7.33、7.70 MJ/kg。采用饲养试验和消化代谢试验测定育肥后期锦江去势公牛生长性能及能量代谢指标,并建立消化能和代谢能能量需要模型。预试期10 d,正试期128 d。结果表明:①D、E组育肥后期锦江去势公牛的总能采食量较其他组显著降低(P0.05)。②B组肥后期锦江去势公牛能量利用效率最高,总能消化率、总能代谢率分别为90.59%和83.36%。③育肥后期锦江去势公牛日增重与消化能采食量和代谢能采食量存在高度线性正相关(R~2=0.997、R~2=0.993),其消化能、代谢能需要量的回归方程分别为:DE_m=0.770W~(0.75)+40.088×ADG;ME_m=0.645W~(0.75)+38.603×ADG(其中DE为消化能总需要量(MJ/d);ME为代谢能总需要量(MJ/d);W~(0.75)为单位代谢体重(kg);ADG为平均日增重(kg/d))。综上所述,育肥后期锦江牛的维持消化能总需要量(DE_m)和代谢能总需要量(ME_m)分别为0.770、0.645 MJ/(kg W~(0.75)·d),每千克增重的消化能和代谢能需要量分别为40.088、38.603 MJ。     

青贮水葫芦对饲喂稻草和棉籽饼肉牛养分摄入量和消化率的影响

试验旨在评估日粮添加不同水平青贮水葫芦对饲喂水稻秸秆和棉饼的肉牛养分摄入量及消化率的影响。将平均体重为135 kg的17月龄杂交肉牛作为试验动物,采用4×4的拉丁方设计,青贮水葫芦添加水平为0%、15%、30%和45%。在4个连续28d的试验期中,连续测定自由采食量和消化率。青贮水葫芦、水稻结秸秆和棉饼中粗蛋白质水平分别为174、53和370 g/kg。水稻秸秆中性洗涤纤维含量最高,达到666 g/kg,其次是青贮水葫芦和棉饼,分别是503 g/kg和418 g/kg。随着日粮青贮水葫芦添加水平的升高,水稻秸秆摄入量从3049 g/d降至1014 g/d(P 0.05),与对照组相比,15%～45%青贮水葫芦组蛋白质摄入量分别提高16%、25%和33%(P 0.05)。随着青贮水葫芦水平的升高,中性洗涤纤维消化由581 g/kg降至546 g/kg(P 0.05),酸性洗涤纤维由364 g/kg降至340 g/kg(P 0.05)。45%青贮水葫芦组消化能和代谢能估计值较对照组显著高32%(P 0.05),随着青贮水葫芦添加水平的增加而增加,其中45%青贮水葫芦组有机物消化率最高达72.2%,而对照组表现最低,为47.4%。对照组相比,随着青贮水葫芦添加水平的升高,粗蛋白质消化率分别提高21%、31%和40%(P 0.05)。结论 :肉牛饲喂青贮水葫芦会降低水稻秸秆的摄入量,日粮添加青贮水葫芦提高了粗蛋白质摄入量。有机物、粗蛋白质、中性洗涤纤维和酸性洗涤纤维消化率随青贮水葫芦添加水平的升高而升高。     

饲草藜麦对肉牛生长性能和营养物质消化率的影响

文章旨在研究育肥肉牛饲粮中添加藜麦茎秆对肉牛生长性能和营养物质消化率的影响。试验选择30头健康的西门塔尔杂种公牛,按照体重进行区组设计,随机分为3组,每组10头牛。对照组肉牛饲喂不含藜麦茎秆的饲粮,试验组Ⅰ肉牛饲喂含15%藜麦茎秆的饲粮,试验组Ⅱ肉牛饲喂含30%藜麦茎秆的饲粮。预试期为2周,正试期为12周。试验期间,每天记录肉牛采食量,分别于试验开始和结束测定肉牛空腹体重。正试期第12周进行消化试验,测定营养物质消化率。试验结果表明,饲草藜麦对育肥肉牛干物质采食量和生长性能的影响与添加量有关。育肥肉牛饲粮中添加15%的藜麦茎秆,对肉牛的干物质采食量和生长性能无显著影响(P0.05),而添加30%的藜麦茎秆显著降低了肉牛干物质采食量和生长性能(P0.05)。饲草藜麦对育肥肉牛日粮营养物质消化率受添加量影响。育肥肉牛饲粮中添加15%的藜麦茎秆不影响肉牛干物质采食量和生长性能(P0.05),添加30%的藜麦茎秆显著降低了有机物和粗蛋白质的消化率(P0.05),对中性洗涤纤维和酸性洗涤纤维消化率无显著影响(P0.05)。因此,饲草藜麦可作为育肥肉牛的粗饲料来源替代部分全株玉米青贮,本试验中以15%添加量为宜。     

生长期西藏白绒山羊能量和蛋白质需要量研究

为了确定生长期西藏白绒山羊的能量、蛋白质需要量,本研究以24只体重相近、健康状况良好的3月龄西藏绒山羊母羊为研究对象,按消化能和粗蛋白两因子2×3水平的试验设计随机分为6组,进行为期90d的饲养试验和14d的消化代谢试验。结果表明:(1)日粮能量水平可显著增加试验羊的日增重(P0.05);日粮蛋白水平对末期体重、日增重和干物质采食量均有极显著影响(P0.01);日粮能量和蛋白水平对日增重和干物质采食量有显著的互作效应(P0.05)。(2)日粮蛋白水平可极显著地影响氮代谢(P0.01);日粮能量和蛋白水平仅对粪氮有显著的互作效应。(3)日粮能量水平对食入总能、甲烷能、总能消化率和总能代谢率有显著影响(P0.05);日粮蛋白水平对甲烷能、总能消化率和总能代谢率有显著影响(P0.05);日粮能量和蛋白水平对食入总能、甲烷能、总能消化率、总能代谢率和消化能代谢率有显著的互作效应(P0.05)。因此,生长期西藏白绒山羊日粮适宜的消化能和代谢能水平分别为11.09～12.03MJ/kg和9.42～10.13MJ/kg,适宜的粗蛋白和可消化粗蛋白水平分别为10.35%～11.29%和5.74%～6.47%。     

不同脂肪源对泌乳奶牛日粮消化能值的影响

本试验旨在研究供给含不同脂肪酸组成(长链和饱和度)和化学组成(游离脂肪酸、脂肪酸钙盐和甘油三酯)的脂肪源对泌乳奶牛日粮消化能浓度和消化能采食量的影响。对照组日粮中添加2.9%的长链脂肪酸,3个处理组日粮中分别添加3%含饱和(C18∶0)游离脂肪酸(SFA)、脂肪酸钙盐(CaFA)和富含C16∶0的甘油三酯(TAG)的脂肪,主要用于替代日粮淀粉。研究结果表明,CaFA处理组泌乳奶牛干物质采食量(22.8kg/d)低于对照组(23.6kg/d)和TAG处理组(23.8kg/d),但与SFA处理组相当(23.2kg/d)。与对照组相比,处理组日粮由于提高了泌乳奶牛乳脂率,乳脂校正乳产量高于对照组,但在脂肪处理各组间,生鲜乳产量和乳成分没有区别。4组日粮的干物质消化率、能量消化率、碳水化合物组分消化率及蛋白消化率没有影响。CaFA处理组日粮长链脂肪酸消化率最高(76.3%),对照组和SFA日粮处理组居中(70.3%),TAG日粮处理组最低(63.3%)。与对照组日粮相比,脂肪处理组日粮含更高的消化能(12.31MJ与11.89MJ),消化能采食量高于对照组,但脂肪处理各组间消化能采食量没有区别,这可能是由于供给脂肪的包被率较低或试验处理组之间干物质采食量和它营养成分消化率区别较小,导致各试验处理不同脂肪酸差异较大的消化率并没有在消化能采食量这个指标上表现出来。     

套算法用于估测肉用羊单一谷物饲料代谢能值及养分消化率的探索

本试验旨在研究使用套算法估测肉用羊单一谷物饲料能值的可行性及适宜的替代比例。试验选取54只体重为(48.3±1.3)kg的杜寒杂交F1代去势公羊,采用完全随机区组设计,平均分为9组,分别饲喂1种基础饲粮和8种不同小麦替代比例的试验饲粮,进行消化代谢和气体代谢试验测定消化能和代谢能,结合套算法计算小麦的消化能和代谢能及养分消化率,以确定其适宜的替代比例。结果表明:1)随着替换比例的增加,饲料中的各种养分的消化率逐渐升高,饲料中粪能逐渐降低,尿能、消化能和代谢能逐渐升高。2)根据套算法计算公式计算出小麦的总能、干物质、有机物、粗蛋白质的消化率在任何替换水平差异均不显著(P0.05)。3)当小麦替换饲粮比例为28.37%~45.95%时,套算法所得的小麦消化能(14.55 MJ·kg~(-1))与NRC的推荐值(14.52 MJ·kg~(-1))基本一致;套算法所得小麦的代谢能(11.86 MJ·kg~(-1))与通过经验公式(消化能×0.82)的计算值(11.91 MJ·kg~(-1))接近。综上所述,套算法可以用于估测肉用羊单一谷物饲料代谢能值及养分消化率,且替换比例以28.37%~45.95%为宜,本试验中小麦替代饲粮的最佳比例为28.37%。     

能量水平对生长猪生产性能、养分消化率和血清生化指标的影响

选择体重(20.40±2.57)kg的健康渝荣1号配套系商品猪60头,随机分为5组,分别饲喂消化能浓度为13.19、14.10、14.35、14.69 MJ/kg和14.90 MJ/kg的饲粮,测定其生产性能和血清生化指标;同时进行消化试验,测定饲粮的养分消化率。结果表明:采食量和饲料增重比随消化能水平上升而下降,14.90 MJ/kg组采食量极显著低于13.19 MJ/kg组(P<0.01),14.69 MJ/kg组和14.90 MJ/kg组饲料增重比显著低于13.19 MJ/kg组(P<0.05);14.69 MJ/kg组日增重最高(P>0.05)。14.90 MJ/kg组血清总胆固醇浓度显著高于13.19 MJ/kg组和14.10 MJ/kg组(P<0.05)。各常规养分消化率随消化能水平提高而上升。由此可见,提高生长猪饲粮能量水平,能够提高营养物质的消化率、降低采食量和饲料增重比;在本试验条件下,消化能水平为14.69 MJ/kg时日增重最佳。     

生物秸秆对肉鸡表观代谢能的影响及替代玉米适宜比例的研究

本试验旨在研究肉鸡对生物秸秆的表观代谢能及其替代玉米的适宜比例.生物秸秆代谢能的测定试验选择24只42日龄健康的爱拔益加(AA)肉鸡,随机分为3个处理,每个处理8只鸡.处理1饲喂含8％生物秸秆的基础饲粮,处理2饲喂以30％的生物秸秆代替基础饲粮中能量饲料和蛋白质饲料的饲粮,处理3采用强饲法进行测定.生物秸秆代替玉米的试验选择150只42日龄健康的AA肉鸡,随机分为5个处理,每个处理5个重复,每个重复6只鸡.对照组饲喂基础饲粮,试验组分别在基础饲粮中用4％、8％、12％生物秸秆代替玉米(代谢能按照差量法计算结果12.46 MJ/kg计)及8％生物秸秆代替玉米(代谢能按照强饲法计算结果5.30 MJ/kg计,添加豆油,使其代谢能水平与对照组相同).结果表明:1)基础饲粮的代谢能为12.63 MJ/kg,采用差量法推算出肉鸡对生物秸秆的表观代谢能为12.46 MJ/kg,而采用套算法和强饲法测定生物秸秆的表观代谢能分别为4.38和5.30 MJ/kg.2)与对照组相比,4％和8％的生物秸秆代替玉米组中性洗涤纤维和酸性洗涤纤维的代谢率显著升高(P＜0.05),而12％的生物秸秆代替玉米组表观能量的代谢率显著降低(P＜0.05).由此得出,套算法和强饲法低估了生物秸秆的表观代谢能,而差量法更能准确反映生物秸秆的表观代谢能;在肉鸡饲粮中生物秸秆可以替代4％ ～8％的玉米.     

Energy and protein requirements for growth and maintenance of F1 Nellore x Red Angus bulls, steers, and heifers

A comparative slaughter trial was conducted with 36 F1 Nellore x Red Angus calves (12 steers, 12 bulls, and 12 heifers), averaging 274 kg of BW, to assess the net requirements of protein and energy for growth and maintenance. Three cattle from each group (i.e., steers, bulls, and heifers) were slaughtered at the beginning of the trial to determine the initial body composition. The remaining calves were randomly assigned to 1 of 3 treatments: maintenance (diet containing 70% of DM as corn silage fed at 1.2% of BW daily) or concentrate at 0.75 or 1.5% of BW daily with corn silage available for ad libitum consumption. The diets were isonitrogenous (2% N, DM basis). The experimental design provided ranges in ME intake, BW, and ADG for the development of regression equations to predict the maintenance requirements for NE and net protein (MRNE and MRNP, respectively) and the growth requirement for NE and net protein (GRNE and GRNP, respectively). After 84 d of growth, the cattle were slaughtered. The cleaned gastrointestinal tracts, organs, carcasses, heads, hides, tails, feet, blood, and tissues were weighed to measure empty BW (EBW). These parts were ground separately and subsampled for chemical analyses. For each animal within a period, DMI was measured daily and samples of feces were collected to determine diet digestibility. There were no differences in MRNE (P = 0.06) among groups. The combined data indicated a MRNE of 71.2 kcal x kg(-0.75) of EBW x d(-1), with a partial efficiency of use of ME to NE(m) of 0.71. The partial efficiency of use of ME to NE for growth was 0.54 for bulls, 0.47 for steers, and 0.54 for heifers. The GRNE for steers and heifers were similar (P = 0.15) but were 18.7% greater (P = 0.03) for steers and heifers than for bulls. The MRNP did not differ among groups and averaged 2.53 g of CP x kg(-0.75) of EBW x d(-1). Likewise, GRNP was not different among groups. The percentage of retained energy deposited as protein (RE(p)) increased as the content of retained energy in the gain (RE(c), Mcal/kg of empty body gain) decreased. The RE(p) equation of the pooled data was 46.5 x e(-0.2463 x RE(c)). We conclude that the energy requirement of crossbred Bos indicus x Bos taurus for maintenance might be less than that of purebred Bos taurus and that RE(p) is nonlinearly, negatively correlated with RE(c). The GRNE was less for bulls than for steers and heifers. However, we found no differences in MRNE, MRNP, and GRNP for bulls, steers, and heifers of Nellore x Red Angus crossbreds.     

The development of a metabolizable energy system for horses

The development of a metabolizable energy (ME) system for horses is described. Predictive equations for gross energy and digestible energy (DE) are revisited. The relationship between feed protein content and renal energy losses and the relationship between feed fibre content and methane energy losses were analysed in a literature review to develop predictive equations for ME. In horses, renal energy losses are much higher than losses by methane energy. Renal energy losses were correlated more strictly to protein intake than to digestible protein intake. The reason probably is that per gram of digestible crude protein energy losses are higher for roughage than for concentrates presumably because phenolic acids of forage cell walls contribute to higher urinary energy losses. However, digestibility of protein is lower in forages than in concentrates. The net result is a rather constant urinary energy loss of 0.008 MJ/g of crude protein in the feed. Methane losses in horses are smaller than in ruminants, presumably because of reductive acidogenesis in hind gut fermentation. Methane energy losses in equines are closely related to crude fibre intake. The mean methane energy losses amount to 0.002 MJ ME/g of crude fibre which can be used to correct for methane losses. Both corrections can be made for any predictive equation for DE. Metabolizable energy is then calculated as follows: ME MJ/kg = DE MJ/kg – 0.008 MJ/g crude protein – 0.002 MJ/g crude fibre. The equation of Zeyner and Kienzle (2002) to predict DE was adapted as mentioned above to predict ME: ME (MJ/kg dry matter) = ?3.54 + 0.0129 crude protein+0.0420 crude fat?0.0019 crude fibre+0.0185 N‐free extract (crude nutrients in g/kg dry matter).     

全株玉米青贮饲养肉牛最佳日粮组合模式研究

对肉牛常用饲料进行营养价值评定,并选择36头6～24月龄西杂肉牛分4组分别采食不同组合日粮,试验期63～68 d.结果表明,不同饲料之间蛋白含量、有效降解率和有效能含量存在较大的差异.肉牛代谢体重干物质采食量与日粮粗蛋白含量之间存在极显著正相关关系,日增重随代谢体重采食量的增加呈直线增加,经济效益随肉牛日增重的增加而增加.以青贮 秸秆 0.5 kg肉牛浓缩料、青贮 秸秆 2 kg肉牛精料补充料、青贮 牧草 0.5 kg肉牛浓缩料、青贮 牧草 2 kg肉牛精料补充料日粮组合分别饲养西杂肉牛,日增重(ADG)分别为0.66 kg、0.90 kg、0.92 kg、1.08 kg;体况评分(BCS)分别增加0.33分、0.42分、0.56分、0.69分;日盈利分别为3.44元、4.22元、4.70元、4.41元.说明,以全株玉米青贮 优质牧草粗饲料组合饲养肉牛,再补饲含高蛋白和能促进肉牛生长及提高纤维饲料消化率的瘤胃微生物所必须矿物质的肉牛浓缩料或肉牛精料补充料,可使肉牛达到较好的增重,并获得较高的收益.     

回归分析法评价4种麦类饲料原料的肉鸡有效能值

本试验旨在评价大麦、黑小麦、小麦和黑麦4种麦类饲料原料在肉鸡上的有效能值,以期优化现有配方数据库,逐步实现饲粮营养的精准供给。采用回归分析法,试验分2批进行,试验1评价大麦和黑小麦的肉鸡回肠消化能(IDE)、代谢能(ME)、氮校正代谢能(MEn),试验2评价小麦和黑麦的肉鸡IDE、ME、MEn。每个批次试验均选用320只1日龄雄性罗斯708肉鸡为试验动物,将其随机分为5个组,每组设8个重复,每个重复8只鸡。1~20日龄为预试期,饲喂基础饲粮;21~28日龄为试验期,分别饲喂基础饲粮和试验饲粮。试验1的5个组21~28日龄所喂饲粮如下:基础饲粮、含250 g/kg大麦的饲粮、含500 g/kg大麦的饲粮、含250 g/kg黑小麦的饲粮、含500 g/kg黑小麦的饲粮。试验2的5个组21~28日龄所喂饲粮如下:基础饲粮、含250 g/kg小麦的饲粮、含500 g/kg小麦的饲粮、含250 g/kg黑麦的饲粮、含500 g/kg黑麦的饲粮。结果表明:在饲粮中添加大麦、黑小麦、小麦和黑麦对肉鸡生长性能均无显著影响(P>0.05)。大麦替代量与干物质、能量的回肠消化率以及干物质、氮、能量的全肠道代谢率,以及IDE、ME、MEn存在极显著的线性降低关系(P<0.01);黑小麦替代量与氮全肠道代谢率、IDE、ME、MEn存在极显著的线性降低关系(P<0.01),且与干物质、能量回肠消化率、IDE存在显著或极显著的二次曲线关系(P<0.05或P<0.01);小麦替代量与干物质、氮、能量、氮校正能量的全肠道代谢率显著或极显著的线性降低关系(P<0.05或P<0.01),且与干物质、能量的回肠消化率和IDE存在显著或极显著的二次曲线关系(P<0.05或P<0.01);黑麦替代量与干物质、能量的回肠消化率以及干物质、氮的全肠道代谢率存在显著或极显著线性降低关系(P<0.05或P<0.01);且与干物质、能量的回肠消化率和干物质、氮、能量、氮校正代谢能的全肠道代谢率以及IDE、ME、MEn存在显著或极显著的二次曲线关系(P<0.05或P<0.01)。通过回归分析得出大麦的肉鸡IDE、ME和MEn分别为9.31、10.50、10.29 MJ/kg,黑小麦分别为10.99、11.80、11.43 MJ/kg,小麦分别为10.59、11.81、11.28 MJ/kg,黑麦分别为11.97、12.56、11.83 MJ/kg。     

Energy metabolism in lactating beef heifers

To obtain measurements of energy balance in lactating beef cows, respiration calorimetry and digestion trials were conducted using seven lactating (613 kg BW) and three nonlactating (598 kg BW) Hereford x Angus heifers fed a pelleted 75% alfalfa:25% concentrate diet. Five measurements of energy balance were obtained at 6- to 7-wk intervals beginning 6 to 10 wk postpartum in lactating heifers and at 6-wk intervals in nonlactating heifers. Milk yield was measured using a combination of weigh-suckle-weigh and machine milking to adapt heifers to milking by machine without the use of oxytocin. Heifers were milked only by machine during measurements of energy balance. Weekly milk yield averages ranged from 8.2 kg/d at wk 5 postpartum to 3.2 kg/d at wk 32 postpartum. When scaled to BW(.75), the regression of NE1 on ME intake and the regression of ME intake on NE1 were remarkably similar to previously published regressions for measurements obtained from lactating Holstein-Friesian cows. The average daily maintenance energy requirement from these regressions was 503 kJ ME/kg BW(.75), a value similar to the average value reported previously for lactating Holstein-Friesian cows (488 kJ/kg (BW.75)). This is in contrast to numerous published comparisons of the maintenance requirements of cattle breed types in the nonlactating state and current NRC standards for estimating maintenance energy requirements of beef and dairy cattle. The results of the present study suggest that when expressed on the basis of BW(.75) the efficiency of utilization of incremental ME above maintenance for milk and tissue energy (i.e., NE1) is similar among lactating Hereford x Angus heifers and lactating Holstein-Friesian cows. The breeds differ in terms of their propensity for milk yield and the resulting partition of ME between milk synthesis and tissue energy retention.     

全株玉米青贮饲料饲喂肉牛增重效果试验

试验选择10月龄左右,体重相近的西门塔尔公牛20头,随机分两组,每组10头,在精料补充水平相同的情况下,饲喂全株玉米青贮饲料和黄贮玉米青贮饲料进行对比分析,为全株玉米青贮饲料饲喂肉牛提供理论数据,并在今后同地区或相似地区的肉牛规模养殖场进行广泛推广。     

半细毛羊5种玉米的可消化粗蛋白质和有效能的测定及其预测

本试验旨在采用概略养分分析法测定5种玉米的营养成分含量以及通过消化代谢试验实测玉米的可消化粗蛋白质含量和有效能值,并利用先采集的4种玉米(奥美特、杰尼336、巨丰66、京科665)数据拟合可消化粗蛋白质、消化能和代谢能分别与营养成分之间的回归方程,然后利用第5种玉米(禾育九)可消化粗蛋白质和有效能数据来对回归方程进行验证和修正。选取16只体重为(56.44±5.11)kg的云南半细毛羊,采用完全随机设计,平均分为4组,每组4只。试验共分2期进行,共6种日粮,分别是基础日粮和5种试验日粮,第1期饲喂4种日粮,第2期饲喂2种日粮。结果表明:京科665的可消化粗蛋白质(DCP)、消化能(DE)和代谢能(ME)含量最高,杰尼336的DCP、DE和ME含量最低;玉米的DE和ME分别与EE呈极显著负相关关系(P<0.01),相关系数分别为-0.985和-0.994;试验所得的预测方程为DCP(g/kg)=258.961-52.624EE(粗脂肪)、DE(MJ/kg)=40.506-6.876EE、DE(MJ/kg)=34.677-6.398EE+0.492CP(粗蛋白质)、DE(MJ/kg)=-115.182-6.572EE+0.473CP+1.525OM(有机物)、ME(MJ/kg)=-1.028+0.945DE、ME(MJ/kg)=2.950+0.916DE-1.060CF(粗纤维)和ME(MJ/kg)=37.586-6.586EE。综合DCP含量和有效能值,京科665的品质最佳,其次是巨丰66、奥美特和禾育九,杰尼336品质最差;以半细毛羊为试验对象得出,可以利用玉米的营养成分预测其DCP含量以及有效能值。     

Effect of high-oil corn on growth performance, diet digestibility, and energy content of finishing diets fed to beef cattle

Sixty crossbred beef steers (initial BW = 412 kg) were used in a 83-d finishing study to determine the effect of feeding dry rolled high-oil corn on performance and total-tract digestibility of finishing diets. Steers were allotted by weight to the following dietary treatments: 1) control corn (C; 82% normal corn, 12% triticale silage), 2) high-oil corn (HO; 82% high-oil corn, 12% silage), and 3) high-oil corn formulated to be isocaloric to C (ISO; 74% high-oil corn, 20% silage). Total lipid content was 4.9% (DM basis) for normal corn and 7.0% for high-oil corn. Steers were individually fed using electronic gates. Quantity of feed offered and refused was recorded daily. Fecal samples were collected on d 63 to 66 of the trial to determine digestibility. Chromic oxide was fed as an indigestible marker for 7 d before fecal collection began. Planned contrasts of HO vs C and ISO vs C were used to assess treatment differences. Dry matter intake was greater for steers fed C vs HO (P < 0.01) or C vs ISO (P < 0.01), but daily gain and feed efficiency were not affected (P > 0.05) by treatments. Digestibility of DM, OM, starch, and GE was greater (P < 0.05) for the HO diet than the C diet, but lipid digestibility did not differ among treatments (P > 0.05). The combined effect of greater GE content and digestibility resulted in greater (P < 0.01) DE content for the HO than for the C diet. Calculated DE of the corn was 8.3% greater (3.74 Mcal/kg; P < 0.01) for the HO diet and 6.5% greater (3.67 Mcal/kg; P < 0.01) for the ISO diet than the corn in the C diet (3.25 Mcal/kg). Dry matter and GE digestibility did not differ (P > 0.05) between the C and ISO diets. Steers consuming ISO had greater (P < 0.05) starch digestibility than steers fed the C diet. Although HO had higher DE, DE intake was similar (P > 0.05) for HO and C due to lower DMI for HO. These results indicate that available energy is greater from high-oil corn than from typical corn, but depressed voluntary feed intake prevented performance improvements and resulted in equal energy intakes between high-oil corn and typical corn diets.     

育成期崂山奶山羊能量需要量

本试验旨在研究饲粮能量水平对育成期崂山奶山羊能量利用率的影响。选择体重为(18.43±0.76)kg的崂山奶山羊育成母羊30只,采用单因素随机分组设计分成3组,每组10个重复,每重复1只羊。分别饲喂粗蛋白质、钙及磷水平基本一致,消化能水平分别为10.40、11.47及12.51 MJ/kg的3种全混合日粮。预试期10 d,正试期90 d。结果表明:1)试验后期3组试羊随着饲粮能量水平的提高,总能消化率依次提高,12.51 MJ/kg组试羊的总能消化率、总能代谢率及消化能代谢率显著高于10.40 MJ/kg组(P0.05);3组试羊的总能、粪能及尿能间呈显著差异(P0.05),10.40 MJ/kg组11.47 MJ/kg组12.51 MJ/kg组;10.40 MJ/kg组试羊的甲烷能显著低于11.47及12.51 MJ/kg组(P0.05)。2)10.40 MJ/kg组试羊末重及平均日增重显著低于11.47及12.51 MJ/kg组(P0.05),但11.47 MJ/kg组与12.51 MJ/kg组间无显著差异(P0.05)。3)育成期崂山奶山羊消化能和代谢能需要量与代谢体重和平均日增重关系的回归公式:DE=0.675W~(0.75)+0.110ADG(P=0.006,R~2=0.982);ME=0.526W~(0.75)+0.076ADG(P=0.027,R~2=0.873)[式中DE为消化能(M J/d),ME为代谢能(M J/d),W~(0.75)为代谢体重(kg),ADG为平均日增重(g)]。综合得出,育成期崂山奶山羊母羊饲粮中消化能以11.47~12.51 MJ/kg(干物质基础)较为适宜。