湿热应激对藏绵羊和山羊生长性能、抗氧化能力以及免疫功能的影响

本试验旨在研究藏绵羊和山羊在相同营养及湿热应激条件下血清激素、抗氧化和免疫指标的变化规律,考察湿热应激对藏绵羊和山羊生长性能、抗氧化能力以及免疫功能影响的差异。选取年龄和体重[(45.83±3.54)kg]相近的藏绵羊与山羊(波尔山羊×本地黄羊)各6只,试验共进行135 d,其中预试期15 d,正试期120 d。每日测定温湿度指数(THI),每月测定藏绵羊和山羊的血清相关指标。结果表明:1)5—7月份,羊舍THI随月份的增加显著升高(P0.05),6—8月份羊舍THI均大于72,因此将6—8月份定为湿热应激期。2)7、8月份藏绵羊和山羊直肠温度和呼吸频率均显著高于5月份(P0.05),且湿热应激期内藏绵羊直肠温度和呼吸频率均显著高于山羊(P0.05)。3)正试期内,湿热应激使得藏绵羊和山羊的干物质采食量最大降幅分别为10.70%和10.44%,平均日增重(ADG)最大降幅分别为50.00%和47.82%。4)羊舍THI由71.17(5月份)升高到76.82(7月份),藏绵羊和山羊血清皮质醇和胰岛素浓度显著升高(P0.05),血清葡萄糖和三碘甲状腺原氨酸浓度显著降低(P0.05)。湿热应激下,藏绵羊血清中生长激素和甲状腺素浓度的最大降幅均大于山羊。5)除藏绵羊7月份和山羊8月份血清总抗氧化能力,藏绵羊和山羊7、8月份的血清超氧化物歧化酶、谷胱甘肽过氧化物酶活性和总抗氧化能力均显著低于5月份(P0.05)外,血清丙二醛浓度均显著高于5月份(P0.05)。湿热应激下,山羊血清超氧化物歧化酶活性、总抗氧化能力和丙二醛浓度变化幅度均大于藏绵羊。6)与5月份相比,藏绵羊和山羊8月份的血清免疫球蛋白A、免疫球蛋白M、免疫球蛋白G和白细胞介素-2浓度显著降低(P0.05),而血清肿瘤坏死因子-α浓度则显著升高(P0.05)。湿热应激下,藏绵羊血清免疫球蛋白、白细胞介素-2和肿瘤坏死因子-α浓度的变化幅度均大于山羊。综上所述,湿热应激状态下藏绵羊和山羊的呼吸频率和直肠温度升高,抗氧化能力和免疫功能降低,从而导致生长性能降低。藏绵羊生长性能和免疫功能受湿热应激影响较大,而山羊抗氧化能力受湿热应激影响较大。     

口饲胰岛素对新生仔猪血浆胰岛素水平及糖代谢的影响

分别给新生正常和子宫内发育迟缓(IUGR)仔猪口饲胰岛素,研究仔猪血浆中胰 岛素水平的变化,以及外源性胰岛素对新生仔猪体内糖代谢的影响。结果证实:人工饲喂3 d 后,血浆中胰岛素浓度极显著提高(P<0．01);肝糖原含量极显著降低(P<0．01);血浆中胰岛 素水平,正常仔猪Ⅰ组显著高于M组(P<0．05);LDH活性,M组和Ⅰ组显著高于N组(P< 0．05),Ⅰ组低于M组(P>0．05);MDH活性和血浆中葡萄糖浓度没有显著变化(P>0．05)。上 述结果证明:仔猪出生0-3 d,糖代谢发生剧烈变化,口饲胰岛素使正常仔猪血浆中胰岛素水 平显著提高,但对仔猪糖代谢影响不显著。     

高能量日粮促进山羊瘤胃上皮细胞增殖的机理研究

为探讨高能量日粮促进山羊瘤胃上皮细胞增殖,促进瘤胃上皮生长的机理,选取18只青年波杂山羊,随机分成高能量组(HL组)和低能量组(LL组),连续饲喂持续42 d。结果显示,与LL组相比,HL组山羊血清胰岛素样生长因子-1(IGF-1)浓度在试验第14天和第35天显著升高;HL组山羊瘤胃上皮p ERK/ERK比率显著高于LL组,表明高能量日粮提高山羊血清IGF-1浓度,并激活其受体后Ras/Raf/MEK/ERK信号转导途径,促进瘤胃上皮细胞增殖。     

不同能量和蛋白质水平饲粮交替饲喂对妊娠母猪繁殖性能、血浆激素含量及抗氧化指标的影响

本试验旨在探究不同能量和蛋白质水平饲粮交替饲喂对妊娠母猪繁殖性能、血浆激素含量及抗氧化指标的影响。试验分为2个阶段,配制6种试验饲粮,妊娠前期试验饲粮:低能量低蛋白质水平饲粮(12.54 MJ/kg、15.55%)、中能量中蛋白质水平饲粮(13.27 MJ/kg、16.47%)、高能量高蛋白质水平饲粮(13.44 MJ/kg、17.86%);妊娠后期试验饲粮:低能量低蛋白质水平饲粮(12.73 MJ/kg、15.96%)、中能量中蛋白质水平饲粮(13.27 MJ/kg、16.47%)、高能量高蛋白质水平饲粮(13.84 MJ/kg、18.13%)。选取2胎、体重相近的加系大白母猪48头,随机分为对照组(早上饲喂中能量中蛋白质水平饲粮,下午饲喂中能量中蛋白质水平饲粮)、试验Ⅰ组(早上饲喂低能量低蛋白质水平饲粮,下午饲喂高能量高蛋白质水平饲粮)、试验Ⅱ组(早上饲喂高能量高蛋白质水平饲粮,下午饲喂低能量低蛋白质水平饲粮),每组16个重复,每个重复1头母猪。每天饲喂2次。妊娠前期中能量中蛋白质水平饲粮每次饲喂1.125 kg,低能量低蛋白质水平饲粮每次饲喂1.150 kg,高能量高蛋白质水平饲粮每次饲喂1.140 kg;妊娠后期中能量中蛋白质水平饲粮每次饲喂1.805 kg,低能量低蛋白质水平饲粮每次饲喂1.800 kg,高能量高蛋白质水平饲粮每次饲喂1.800 kg。试验期114 d。结果表明:1)与对照组相比,试验Ⅰ组妊娠36~90 d的平均日增重(ADG)显著增加(P<0.05);试验Ⅰ组总产仔数高于对照组(P>0.05);试验Ⅰ组活仔数高于对照组(P>0.05)。2)与对照组相比,试验Ⅰ组妊娠35 d的血浆过氧化氢酶(CAT)活性显著升高(P<0.05),试验Ⅰ组妊娠80 d的血浆CAT活性极显著升高(P<0.01),且试验Ⅰ组较试验Ⅱ组显著升高(P<0.05);与对照组相比,试验Ⅱ组妊娠80 d的血浆丙二醛(MDA)含量极显著降低(P<0.01),试验Ⅰ组妊娠35 d的血浆MDA含量显著高于试验Ⅱ组(P<0.05)。3)与对照组相比,试验Ⅰ组妊娠80 d的血浆瘦素(LEP)含量显著升高(P<0.05);试验组妊娠105 d的血浆胰岛素样生长因子-Ⅰ(IGF-Ⅰ)含量极显著低于对照组(P<0.01)。综上所述,与早、晚饲喂相同营养水平饲粮相比,早、晚交替饲喂不同能量和蛋白质水平饲粮可提高妊娠母猪的繁殖性能,影响血浆中激素含量和抗氧化指标。     

添加硫酸盐对生长期山羊的生产性能,酸碱平衡和养分消化率的影响

去势公山羊羔(20只阿尔脾斯山羊和12只安哥拉山羊)饲喂含2.28％N和添加0.11(基础)、0.20、0.28和0.38％硫(CaSO_4)的等氮和等能日粮。在8周生长试验期,添加硫酸盐的山羊ADG呈曲线性提高(P<0.05),DMI趋向于曲线性提高(P<0.07),峰值为0.20％S日粮组。应用DMI作为共变异分析,添加S呈曲线性提高ADG,呈直线性提高S摄入量、粪S排出量和S潴留,添加硫酸盐接近曲线性提高血液L—乳酸盐浓度,但添加硫酸盐对血液硫酸盐、血液胱氨酸、瘤胃氨氮浓度和分离细菌的嘌呤N含量无显著影响。添加硫酸盐呈曲线性提高间歇N潴留,尿酸的尿液排出量随S添加而呈曲线性增加(P<0.01)。通过回归分析最佳日粮S含量为:最大ADG为0.22％S(N:S=10.4:1);最大DMI为0.24％S(N:S=9.5:1);最大N潴留为0.23％(N:S=9.9:1);最大吸收N维持为0.22％S(N:S=10.4:1)。这些结果证实了山羊为满足生长的S需要量(N:S=10:1)。     

不同能量水平日粮对肉仔鸡生长及屠宰性能指标的影响研究

选择3周龄健康、无病、体重无显著差异的肉仔鸡96只,随机分为3组,每组设4 个重复,每个重复8只。分别饲喂蛋白质水平(19．5％)相同而能量水平不同(3．0 Mcal／kg、 3．08 Mcal／kg、3．16Mcal／kg)的3种饲粮。试验结果表明:前两周饲料转化(采食／增重)均以 中能量组(3．08 Mcal／kg)最好,为1．4416±0．1199,但三种不同能量水平对肉仔鸡平均日增 重、平均日耗料、饲料转化率均差异不显著(P>0．05);后两周饲料转化仍以中能量组最好,为 1．6362±0．1346,且显著优于高能量组(P<0．05),而与低能组和中能组之间差异不显著,各 能量处理组蛋白质、粗纤维、钙的代谢率均差异不显著(P>0．05),而磷的代谢率却存在显著 差异(P<0．05),其中,以中等能量组的磷代谢率最高,平均为90．73％;3种能量水平下肉仔鸡 半净膛率、全净膛率均差异不显著(P>0．05),表明能量水平并不影响肉仔鸡屠宰性能。     

饲粮能量水平和养殖环境温湿指数对育肥肉牛生长性能、营养物质表观消化率和血清生化指标的影响

本试验旨在研究饲粮能量水平和养殖环境温湿指数(THI)对育肥肉牛生长性能、营养物质表观消化率和血清生化指标的影响。试验采用3×2双因素设计,选用30头初始体重为(345.4±28.8) kg的中国西门塔尔牛(草原类型群)公牛,随机分为6组,每组5头,在2种养殖环境[室外围栏(THI=31)和日光棚(THI=45)]中分别饲喂低、中、高3种能量水平(综合净能水平分别为6.46、6.96和7.41 MJ/kg)的全混合日粮(TMR)。预试期7 d,正试期63 d。结果表明:在THI=31时,随饲粮能量水平的升高,育肥肉牛的干物质采食量(DMI)逐渐降低,且低能量水平组显著高于高能量水平组(P0.05)。育肥肉牛的平均日增重(ADG)在2种养殖环境THI中均随着饲粮能量水平的升高而增加,而料重比(F/G)则均随着饲粮能量水平的升高而降低,以THI=31时低能量水平组最高,且显著高于其他各组(P0.05)。饲粮能量水平和养殖环境THI的交互作用对DMI、ADG和F/G均有显著影响(P0.05)。THI=31时各能量水平组干物质表观消化率显著低于THI=45时各能量水平组(P0.05)。THI=45时各能量水平组中性洗涤纤维(NDF)表观消化率显著高于THI=31时低能量水平组(P0.05)。THI=45时各能量水平组和THI=31时高能量水平组酸性洗涤纤维(ADF)表观消化率显著高于THI=31时低能量水平组(P0.05)。饲粮能量水平、养殖环境THI及两者的交互作用均显著影响NDF和ADF表观消化率(P0.05)。THI=31时各能量水平组血清葡萄糖含量显著高于THI=45时各能量水平组(P0.05),而总蛋白含量反之。THI=31时低、中能量水平组血清尿素氮含量显著高于THI=45时各能量水平组(P0.05),且其在THI=31和THI=45时均随饲粮能量水平的升高而降低。饲粮能量水平和养殖环境THI的交互作用对除葡萄糖含量外的其他血清生化指标未产生显著影响(P0.05)。综上,当饲粮综合净能水平为6.96 MJ/kg、粗饲料与精饲料配比为45∶55时,在寒冷地区冬季采用日光棚养殖可提高饲粮的营养物质表观消化率,改善育肥肉牛的生长性能。     

能量蛋白水平对冬季舍饲燕山绒山羊公羔生长性能的影响

试验旨在研究不同能量蛋白水平的日粮对冬季舍饲绒山羊公羔生长性能的影响。选择体况良好、体重为(16.17±1.90)kg的4月龄燕山绒山羊断奶公羔90只,按3×3(能量×蛋白)完全随机设计分为9组(n=10),采用3个可消化蛋白(DCP)水平(8.5%、9.5%和10.5%)和3个代谢能(ME)水平(9.5、10.5 MJ/kg和11.5 MJ/kg),设计9种日粮饲喂羔羊。结果表明:(1)羔羊干物质采食量(DMI)和料重比(F/G)随日粮能量水平的提高显著降低(P0.05);蛋白水平显著影响了羔羊DMI(P0.05),对F/G无影响(P0.05)。(2)高能高蛋组(Ⅸ组)日增重(ADG)最高(139 g/d),高能低蛋组(Ⅶ)ADG最低(99 g/d),其他各组间ADG差异不显著(P0.05)。综上所述,中能高蛋组(Ⅵ组)饲料报酬最高,燕山绒山羊公羔日粮的适宜ME和DCP水平分别为10.5 MJ/kg和10.5 g/kg。(3)根据DMI、BW和NDF数据构建燕山绒山羊公羔DMI经验模型为DMI=-0.346+0.086BW~(0.75)+0.831NDF。     

不同能量水平日粮对绵羊脂肪酸合成酶(FAS)基因表达的影响

选择年龄、体重相近的小尾寒羊母羊24只,随机分为3组,分别饲喂不同能量水平的日粮(标准能量、低能量和高能量).采用半定量RT-PCR方法,通过优化反应条件和体系,检测不同能量水平日粮对绵羊尾部脂肪组织中脂肪酸合成酶(FAS)基因表达的影响.结果表明:FAS基因在小尾寒羊尾部脂肪组织中的相对表达量在高能量组中最高,高能量组FAS基因表达量显著高于标准能量组(P<0.05),标准能量组FAS基因表达量显著高于低能量组(P<0.05).FAS基因在小尾寒羊尾部脂肪组织中的表达水平随日粮中能量水平的增加而呈升高的趋势.脂肪酸合成酶基因在小尾寒羊不同脂肪组织的表达量不同,腹部皮下脂肪中FAS基因表达量显著高于尾部和肠系膜脂肪组织(P<0.05).     

云上黑山羊生长育肥公羊能量需要量研究

本试验旨在研究云上黑山羊生长育肥公羊能量需要量。选择体况良好、体重相近(约为30 kg)的云上黑山羊生长育肥公羊50只，随机分为5组，每组10只羊。各组分别饲喂代谢能(ME)水平为8.01(1组)、8.70(2组)、9.39(3组)、10.07(4组)、10.75 MJ/kg(5组)的试验饲粮。预试期15 d，正试期30 d。结果表明：1) 3组的平均日增重(ADG)显著高于其他各组(P<0.05),3组的干物质采食量(DMI)显著高于1、2、5组(P<0.05),3组的料重比(F/G)显著低于其他各组(P<0.05)。2)3组的粗蛋白质表观消化率显著高于其他各组(P<0.05),1组的磷表观消化率显著低于其他各组(P<0.05),2、3组的粗灰分表观消化率显著高于1组(P<0.05),5组的中性洗涤纤维和酸性洗涤纤维表观消化率显著高于1组(P<0.05)。3)3、4、5组的总能摄入量、甲烷能、消化能和ME显著高于1、2组(P<0.05),5组的总能表观消化率显著高于1组(P<0.05)。4)对云上黑山羊生长育肥公羊的ADG、ME和...     

Residual feed intake of purebred Angus steers: effects on meat quality and palatability

Relationships between residual feed intake (RFI) and other performance variables were determined using 54 purebred Angus steers. Individual feed intake and BW gain were recorded during a 70-d post-weaning period to calculate RFI. After the 70-d post-weaning test, steers were fed a finishing ration to a similar fat thickness (FT), transported to a commercial facility, and slaughtered. A subsample of carcasses (n = 32) was selected to examine the relationships among RFI, meat quality, and palatability. Steers were categorized into high (> 0.5 SD above the mean; n = 16), medium (mid; +/- 0.5 SD from the mean; n = 21), and low (< 0.5 SD below the mean; n = 17) RFI groups. No differences were detected in ADG, initial BW, and d 71 BW among the high, mid, and low RFI steers. Steers from the high RFI group had a greater DMI (P = 0.004) and feed conversion ratio (FCR; DMI:ADG; P = 0.002) compared with the low RFI steers. Residual feed intake was positively correlated with DMI (r = 0.54; P = 0.003) and FCR (r = 0.42; P = 0.002), but not with initial BW, d 71 BW, d 71 ultrasound FT, initial ultrasound LM area, d 71 ultrasound LM area, or ADG. The FCR was positively correlated with initial BW (r = 0.46; P = 0.0005), d 71 BW (r = 0.34; P = 0.01), and DMI (r = 0.40; P = 0.003) and was negatively correlated with ADG (r = -0.65; P = 0.001). There were no differences among RFI groups for HCW, LM area, FT, KPH, USDA yield grade, marbling score, or quality grade. Reflectance color b* scores of steaks from high RFI steers were greater (P = 0.02) than those from low RFI steers. There was no difference between high and low RFI groups for LM calpastatin activity. Warner-Bratzler shear force and sensory panel tenderness and flavor scores of steaks were similar across RFI groups. Steaks from high RFI steers had lower (P = 0.04) off-flavor scores than those from low RFI steers. Cook loss percentages were greater (P = 0.005) for steaks from low RFI steers than for those from mid RFI steers. These data support current views that RFI is independent of ADG, but is correlated with DMI and FCR. Importantly, the data also support the hypothesis that there is no relationship between RFI and beef quality in purebred Angus steers.     

色氨酸对5～10周龄扬州鹅生长性能和屠宰性能的影响

选用270只21日龄的扬州公鹅,随机分成6组,每组3个重复,每个重复15只鹅。采用2×3二因子试验设计,采用两种饲喂方式(自由采食和90%限制饲喂,限制饲喂组鹅饲料供给量为前一天自由采食组饲料消耗量的90%)和低、中、高3个色氨酸(Trp)水平(含量分别为0.14%,0.22%和0.30%),分别对3个不同生长阶段的生长性能和屠宰性能指标进行测定。结果表明,在28～42日龄,与低、高Trp组相比,中Trp组扬州鹅平均日采食量和平均日增重显著提高(P<0.05),饲喂方式和Trp水平对扬州鹅平均日采食量、平均日增重和饲料转化率有交互作用(P<0.05);在42～56日龄,自由采食组扬州鹅平均日采食量和饲料转化率极显著高于限制饲喂组(P<0.01),平均日增重显著高于限制饲喂组(P<0.05)。与低、高Trp组相比,中Trp组扬州鹅平均日采食量显著提高(P<0.05),Trp水平对平均日增重和饲料转化率无显著影响(P>0.05),饲喂方式和Trp水平对扬州鹅平均日采食量有交互作用(P<0.05);在56～70日龄,Trp水平对扬州鹅平均日采食量、平均日增重和饲料转化率均无显著影响(P>0.05)。饲喂方式和Trp水平对扬州鹅平均日增重和饲料转化率有交互作用(P<0.05);在28～70日龄,自由采食组扬州鹅平均日采食量和平均日增重极显著高于限制饲喂组(P<0.01)。与低、高Trp组相比,中Trp组扬州鹅平均日采食量和平均日增重显著提高(P<0.05),而Trp水平对饲料转化率无显著影响(P>0.05),饲喂方式和Trp水平对扬州鹅平均日采食量和平均日增重有交互作用(P<0.05)。自由采食组扬州鹅全净膛率、胸肌率和腹脂率显著高于限制饲喂组(P<0.01),随着Trp水平的增加,扬州鹅胸肌率显著增加(P<0.01),而Trp水平对其他屠宰性能指标无显著影响(P>0.05),饲喂方式和Trp水平对扬州鹅腹脂率有交互作用(P<0.01)。由此可知,饲粮中Trp水平过低或过高均会对扬州鹅生长性能产生不利影响,并且这种不利的影响具有阶段性,因此日粮添加适当水平的Trp能够一定程度改善扬州鹅生长性能。     

Relationship between the activity of mitochondrial respiratory chain complexes and feed efficiency in fat-tailed Ghezel lambs

This study was conducted to investigate relationships between mitochondrial respiratory chain complex activities, feed efficiency, and carcass traits in sheep. A group of Ghezel male lambs sired by a single ram were randomly allotted to individual pens. The lambs were fed ad libitum with a fattening diet containing 30% roughage (corn silage and alfalfa hay) and 70% concentrate for 70 d to individually phenotype each lamb for feed conversion ratio (FCR), adjusted FCR (aFCR), and residual feed intake (RFI). The lambs were then humanely killed and the liver, abdominal fat, pelvic fat, cardiac fat, warm carcass weight, and cold carcass weight, as well as the cross-sectional area of the LM and the fat depth over the 12th rib, were determined. A portion of LM was obtained to determine mitochondrial protein and respiratory chain complex activities (complexes I to V). Statistical analysis was carried out based on lambs exhibiting high and low RFI (n = 8), FCR (n = 8), or aFCR (n = 8) phenotypes. The lambs exhibiting the high-RFI phenotype consumed 110 g more feed daily (P < 0.05) than did the phenotype exhibiting low RFI, with no difference in ADG. Conversely, there was no difference in feed intake between the low- or high-FCR groups, but sheep exhibiting the low-FCR phenotype gained 70 g more (P < 0.05) per day compared with those exhibiting the high-FCR phenotype. It was determined that all 5 respiratory chain complex activities were greater (P < 0.05) in sheep exhibiting the low-RFI phenotype compared with those exhibiting the high-RFI phenotype, with significant (P < 0.001) negative correlation coefficients between RFI and respiratory chain complex activity. When efficiency was assessed using FCR, only activities of respiratory chain complexes III, IV, and V were less (P < 0.05) in the low-FCR phenotype compared with the high-FCR phenotype, and there were no differences (P > 0.1) in respiratory chain complex activities between groups when FCR was adjusted for metabolic BW (aFCR). There were no differences (P > 0.1) in carcass traits among any of the feed efficiency phenotypes. The results suggest that the inclusion of respiratory chain complex activities in breeding programs may be helpful in selecting for sheep exhibiting the low-RFI phenotype.     

Effects of supplement type on performance, reproductive, and physiological responses of Brahman-crossbred females

Two experiments were conducted to compare the performance and physiological responses of forage-fed beef females supplemented with either a molasses-based (ML) or a citrus pulp-based (CT) supplement. In Exp. 1, BW gain, reproductive performance, and concentrations of blood urea N (BUN), plasma glucose, insulin, IGF-I, and progesterone (P4) were assessed in 60 Brahman x Angus heifers supplemented 3 times weekly with either ML or CT. Supplement intakes were formulated to be isocaloric and isonitrogenous. Reproductive performance was not affected by treatments, but mean BW gain was greater (P < 0.01) for heifers fed CT than for those fed ML (0.40 vs. 0.30 kg/d). Mean plasma concentrations of glucose, insulin, and IGF-I were greater (P < 0.05) for heifers fed CT, whereas BUN was greater (P < 0.05) for heifers fed ML. Mean plasma P4 concentration did not differ between treatments, but both groups had lower plasma P4 concentrations during days that supplements were offered (P < 0.01). In Exp. 2, forage DMI and concentrations of BUN, plasma glucose, insulin, IGF-I, and P4 were assessed in 24 Brahman x British mature cows supplemented with the same treatments described in Exp. 1. Overall forage DMI did not differ between treatments, but a day effect and a treatment x day interaction were detected (P < 0.05). Both groups consumed less forage during the days on which the supplements were offered (P < 0.01), and forage DMI for cows fed CT was less (P < 0.05) than for cows fed ML during those days. No differences were detected in any blood or plasma measurement. In addition, no differences in concentrations of P4 were detected between CT- and ML-fed cows. We concluded that CT-supplemented heifers had greater BW gain compared with ML-supplemented heifers, but no differences in reproductive performance were observed. We also observed that CT-supplemented cows had a greater variability in forage DMI compared with ML-supplemented cows.     

Relationship between feeding behavior and performance of feedlot steers fed barley-based diets

The relationship between feeding behavior and performance of 274 feedlot cattle was evaluated using Charolais cross steers from 2 consecutive years averaging 293 ± 41 kg for yr 1 (n = 115) and 349 ± 41 for yr 2 (n = 159). Steers were blocked by BW and assigned to 3 (yr 1) or 4 (yr 2) feedlot pens equipped with a radio frequency identification system (GrowSafe Systems). Each pen contained 5 feeding stalls that allowed individual animal access to a feed tub suspended on load cells. The system recorded animal identification, duration, and frequency of feedings as well as the amount of feed consumed during each visit. Daily variation in DMI (DVI), calculated as the absolute difference in DMI from one day to the next, as well as eating rate were determined for each steer. Barley-based diets were delivered to meet steer ad libitum intake over the 213- and 181-d feeding periods for yr 1 and 2 of the study, respectively. The backgrounding periods included the first 85 and 56 d of yr 1 and 2, respectively, in which steers were fed a 14 to 30% concentrate diet, whereas the finishing periods included the last 116 and 101 d of feeding in yr 1 and 2, respectively, with the diet consisting of 77.9% concentrate. Steers were weighed individually every 14 d. To relate feeding behavior to performance, steers were grouped by ADG and G:F and categorized as high, average, or low (based on 1 SD greater than and less than the mean). In the backgrounding and finishing periods of both years of the study, steers classified as having high ADG exhibited greater (P < 0.001) DVI than steers classified as having average or low ADG. Total daily DMI was also greater (P < 0.001) for steers in the high ADG group than those in the low ADG group. Overall, those steers with the greatest G:F also tended (P = 0.15) to have greater DVI than average or low G:F steers. Compared with average or low G:F steers, DMI by high G:F steers in both years of the study was less during backgrounding, finishing, and overall (P = 0.02). Bunk visits and bunk attendance duration were less frequent and shorter (P ≤ 0.01) overall for high compared with low G:F steers. In this study, steers with more variable eating patterns exhibited greater ADG and tended to have greater G:F, a finding that is contrary to industry perception.     

Effects of supplementation on voluntary dry matter intake, growth and nutrient digestibility of the Fiji Fantastic sheep on a basal diet of Guinea grass (Panicum maximum)

Eighteen growing Fiji Fantastic (FF) sheep (nine ram lambs and nine ewe lambs), 5–6 months old, pre-experimental average body weight of 25.6 ± 0.82 kg were randomly divided into three groups of six and allotted to the treatments designated as A: Guinea grass (Panicum maximum); B: Guinea grass + concentrate mixture; and C: Guinea grass + crushed wheat grain in a completely randomized design experiment that lasted for 92 days. Total DM intake of sheep on forage + concentrate mixture were significantly higher (P < 0.001) than those on forage + crushed wheat grain and forage alone. Average daily gains (ADG) were 30, 75 and 42 g/day for forage, forage + concentrate mixture and forage + crushed wheat grain, respectively. ADG was significantly (P < 0.001) higher in sheep on forage + concentrate mixture. Daily protein intakes and BUN concentration were 3.59, 10.39 and 5.60 g/kg^0.75/day; and 6.0, 9.7 and 6.0 mmol/l for sheep on forage alone, forage + concentrate mixture and forage + crushed wheat grain, respectively. BUN and glucose concentrations at the post-experimental period were significantly (P < 0.001) higher in sheep on forage + concentrate mixture. DM, organic matter (OM), crude protein (CP), acid detergent lignin (ADL), hemicellulose and energy digestibility were significantly (P < 0.001) higher in sheep on the concentrate mixture while neutral detergent fibre (NDF) digestibility was significantly (P < 0.001) higher in sheep fed crushed wheat grain. Sheep on the concentrate mixture were also significantly (P < 0.002) higher in metabolizable energy intake (MEI). Sheep on concentrate mixture had higher organic matter (OM) and crude protein (CP) digestibility, high DMI and ADG. In conclusion this experiment has provided some relevant lacking information on the average DMI and ADG of the FF sheep and a concentrate mixture of 16.5% CP plus 19.0 MJ GE/kg BW seems ideal to meet the protein and energy requirements of the FF sheep for growth in the tropical environment of Fiji. Finally data obtained also demonstrated the influence of supplementary concentrate feeding on DMI and ADG of the FF sheep.     

EM发酵玉米秸秆饲喂陕北白绒山羊效果研究

为研究EM发酵玉米秸秆饲喂陕北白绒山羊效果,试验选择16只健康状况良好的1周岁空怀期陕北白绒山羊,将其随机分成A、B两组,每组8个重复,每个重复1只。试验基础日粮为苜蓿干草200g＋精料补充料200g。A组饲喂基础日粮＋常规玉米秸秆;B组饲喂基础日粮＋EM发酵玉米秸秆,试验中A、B两组自由采食秸秆。试验共40d,其中预饲期18d10结果显示：（1）B组平均干物质采食量显著高于A组（P〈0.05）,其中玉米秸秆采食量较A组高22.53%（P〈0.05）;（2）B组DMD、GED和CPD分别较A组高3.65%（P〈0.05）、4.18%（P〈0.05）和8.02%（P〈0.01）;（3）B组平均日增重和饲料转化效率分别为45.45g和74.19g/kg,极显著高于A组的22.27g和39.32g/kg（P〈0.01）。综上所述,EM发酵的玉米秸秆可以达到开发秸秆粗饲料、减少资源浪费、减少公害、降低生产成本的目的。     

Different measures of energetic efficiency and their phenotypic relationships with growth, feed intake, and ultrasound and carcass merit in hybrid cattle

Residual feed intake (RFI) has been proposed as an index for determining beef cattle energetic efficiency. Although the relationship of RFI with feed conversion ratio (FCR) is well established, little is known about how RFI compares to other measures of efficiency. This study examined the phenotypic relationships among different measures of energetic efficiency with growth, feed intake, and ultrasound and carcass merit of hybrid cattle (n = 150). Dry matter intake, ME intake (MEI), ADG, metabolic weight (MWT), and FCR during the test averaged 10.29 kg/d (SD = 1.62), 1,185.45 kJ/(kg0.75 x d) (SD = 114.69), 1.42 kg/d (SD = 0.25), 86.67 kg0.75 (SD = 10.21), and 7.27 kg of DM/kg of gain (SD = 1.00), respectively. Residual feed intake averaged 0.00 kg/d and ranged from -2.25 kg/d (most efficient) to 2.61 kg/d (least efficient). Dry matter intake (r = 0.75), MEI (r = 0.83), and FCR (r = 0.62) were correlated with RFI (P < 0.001) and were higher for animals with high (>0.5 SD) RFI vs. those with medium (+/-0.5 SD) or low (<0.5 SD) RFI (P < 0.001). Partial efficiency of growth (PEG; energetic efficiency for ADG) was correlated with RFI (r = -0.89, P < 0.001) and was lower (P < 0.001) for high- vs. medium- or low-RFI animals. However, RFI was not related to ADG (r = -0.03), MWT (r = -0.02), relative growth rate (RGR; growth relative to instantaneous body size; r = -0.04), or Kleiber ratio (KR; ADG per unit of MWT; r = -0.004). Also, DMI was correlated (P < 0.01) with ADG (r = 0.66), MWT (r = 0.49), FCR (r = 0.49), PEG (r = -0.52), RGR (r = 0.18), and KR (r = 0.36). Additionally, FCR was correlated (P < 0.001) with ADG (r = -0.63), PEG (r = -0.83), RGR (r = -0.75), and KR (r = -0.73), but not with MWT (r = 0.07). Correlations of measures of efficiency with ultrasound or carcass traits generally were not different from zero except for correlations of RFI, FCR, and PEG, respectively, with backfat gain (r = 0.30, 0.20, and -0.30), ultrasound backfat (r = 0.19, 0.21, and -0.25), grade fat (r = 0.25, 0.19, and -0.27), lean meat yield (r = -0.22, -0.18, and 0.24), and yield grade (r = 0.28, 0.24, and -0.25). These phenotypic relationships indicate that, compared with other measures of energetic efficiency, RFI should have a greater potential to improve overall production efficiency and PEG above maintenance, and lead to minimal correlated changes in carcass merit without altering the growth and body size of different animals.     

Growth and slaughter traits of Boer x Spanish, Boer x Angora, and Spanish goats consuming a concentrate-based diet.

The number of Boer crossbred meat goats has been increasing rapidly, although how their growth and slaughter traits compare with those of Spanish goats and influences of maternal genotype have not been thoroughly evaluated. This information would be useful to achieve optimal meat goat production systems and yield of goat products desired by consumers. Therefore, postweaning growth (9 to 24 wk of age) and slaughter traits (212 +/- 5.0 d of age) of Boer x Spanish, Spanish, and Boer x Angora wethers (n = 16, 18, and 18 for growth measures, respectively, and n = 6 per genotype for slaughter traits) consuming a concentrate-based diet were compared. Over the 16-wk performance period, ADG, DMI, and ADG:DMI were greater (P < 0.05) for Boer crossbreds than for Spanish goats (ADG: 154, 117, and 161 g; DMI: 646, 522, and 683 g/d; ADG:DMI: 263, 235, and 261 g/kg for Boer x Spanish, Spanish, and Boer x Angora, respectively). Dressing percentage (46.3, 47.3, and 47.0% of BW; SE = 1.21) and quality grade score (11.17, 9.67, and 11.17 for Boer x Spanish, Spanish, and Boer x Angora, respectively; SE = 0.66 [12 = Choice+; 11 = Choice; 10 = Choice-; 9 = Good+]) were similar among genotypes. Weights of some noncarcass components were greater for Boer crossbreds than for Spanish goats, but relative to empty BW, noncarcass component weights were similar among genotypes. Concentrations of moisture, ash, fat, and protein in carcass and noncarcass components did not differ among genotypes. Contributions to the carcass of different primal cuts were similar among genotypes, and there were few differences in concentrations of separated lean, bone, and fat in primal cuts. In conclusion, when consuming a concentrate-based diet, early postweaning growth rate was similar between Boer x Spanish and Boer x Angora wethers and greater for Boer crossbreds than for Spanish wethers. Slaughter traits were primarily related to differences in final BW.     

不同添加形式的亚麻油对肉羊生长性能、屠宰性能及血清生化指标的影响

本试验旨在研究日粮中添加不同形式的亚麻油对肉羊生长性能、屠宰性能及血液脂代谢相关生化指标的影响。选取体重相近的健康杜泊羊（♂）×小尾寒羊（♀）杂交F2代公羔24只，采用单因子完全随机试验设计，随机分为4组，每组6只。CON组为对照组，饲喂基础日粮；LO、L、LOM组为试验组，分别添加含油量4%的亚麻油、亚麻籽炒粒、亚麻油微胶囊脂末。试验期50 d。结果显示：①日粮添加亚麻籽、亚麻油微胶囊脂末能够提高羔羊的生长性能和屠宰性能，L、LOM组平均日增重（ADG）均显著高于LO组（P < 0.05）；②LOM组背膘厚显著高于CON组及L组（P < 0.05），但各组间其他屠宰性能指标差异均不显著（P > 0.05）；③不同形式的亚麻油均能够显著提高血清中总胆固醇（TC）、低密度脂蛋白胆固醇（LDL-C）、高密度脂蛋白胆固醇（HDL-C）含量（P < 0.05），显著降低LO及L组（INS）浓度（P < 0.05），血清中葡萄糖（GLU）、甘油三酯（TG）及瘦素（LEP）含量虽有上升趋势，但各组间差异不显著（P > 0.05）；④不同形式的亚麻油对瘤胃pH影响不显著（P > 0.05），但LOM组可显著提高瘤胃氨态氮（NH₃-N）浓度和微生物蛋白（MCP）含量（P < 0.05）。综上所述，亚麻油不同添加形式对血液脂代谢没有产生不良影响，可提高血清TC、LDL-C及HDL-C含量，降低INS的浓度；直接添加亚麻油将对肉羊生长有一定的负面影响，可降低ADG及MCP浓度；添加亚麻籽炒粒和亚麻油微胶囊脂末均可提高肉羊生产性能和瘤胃发酵功能，但添加微胶囊脂末效果更好。