日粮蛋白能量比对3-5月龄后备奶牛乳腺发育及相关激素的影响

试验旨在研究粗蛋白与消化能之比(CP∶DE)对3～5月龄中国荷斯坦犊牛乳腺发育及相关激素的影响。选取30头70日龄断奶后正常过渡的中国荷斯坦犊牛,分为A、B、C3组,每组10头。饲喂CP∶DE(g/MJ)分别为13.5∶1、13.7∶1、14.6∶1的日粮,试验期90d。结果表明:A、B、C3组间平均日增重依次为0.83、0.80、0.81kg/d(P>0.05),试验牛乳头长度变化都随日龄的增加而增加(P>0.05),孕激素随着后备牛日龄的增加而增加,蛋白能量比为14.6∶1处理组后备牛的催乳素和生长激素的浓度显著高于蛋白能量比为13.5∶1和13.7∶1处理组(P<0.05)。3-5月龄后备奶牛生长速度及乳腺发育在日粮蛋白能量比为13.5∶1-14.6∶1范围内没有显著差异。     

不同中性洗涤纤维来源饲粮对荷斯坦公犊牛生长性能、消化代谢和血清生化指标的影响

本试验在饲粮中性洗涤纤维(NDF)水平相同的条件下,研究以苜蓿干草(AH)或大豆皮(SH)为主要NDF来源的全混合日粮对荷斯坦公犊牛生长性能、消化代谢和血清生化指标的影响。选取30头105日龄的荷斯坦公犊牛,按照随机区组设计分成2组,每组15头,分别饲喂AH和SH为主要NDF来源的全混合日粮。预试期15d,正试期60d。结果表明:1)试验全期(120~180日龄),SH饲粮组犊牛的料重比显著低于AH饲粮组(P<0.05);120~135日龄时,SH饲粮组犊牛的平均日增重显著高于AH饲粮组(P<0.05)。2)170日龄时,SH饲粮组犊牛的粪排出量、粪能、尿能和粪氮显著低于AH饲粮组(P<0.05),SH饲粮组犊牛的干物质、有机物、NDF和酸性洗涤纤维的表观消化率显著高于AH饲粮组(P<0.05),SH饲粮组犊牛的总能表观消化率、总能代谢率、消化能代谢率、沉积氮、氮沉积率和氮表观消化率显著高于AH饲粮组(P<0.05)。3)180日龄时,SH饲粮组犊牛的血清β-羟丁酸含量显著低于AH饲粮组(P<0.05)。综上所述,SH是120~180日龄荷斯坦公犊牛较好的NDF来源,能够满足犊牛对营养物质的需要,相比AH饲粮,饲喂SH饲粮能够提高犊牛的营养物质表观消化率及能量和氮的利用率。     

复合益生菌对4～6月龄犊牛生长性能、养分表观消化率和血液生化指标的影响

试验旨在探究不同添加量复合益生菌对4～6月龄荷斯坦犊牛生长性能、养分表观消化率及血液生化指标的影响。选择体重(152.1±1.5)kg、4月龄母犊牛32头,随机分成4组,分别饲喂含0(对照组)、1、2、3g/kg复合益生菌的颗粒化全混合日粮,其中复合益生菌含有地衣芽孢杆菌(活菌数≥2.0×10~9CFU/g)、枯草芽孢杆菌(活菌数≥2.0×10~9CFU/g)和米曲霉(活菌数≥2.0×10~4CFU/g)。每组犊牛每天摄入益生菌总量分别为0、1.8×10~(10)、3.6×10~(10)、5.4×10~(10)CFU/d。预试期7d,正试期56d。结果表明:3g/kg复合菌组犊牛的平均日增重较对照组高244.45 g(P0.05),耗料增重比低于对照组(P0.01);3 g/kg复合菌组粗蛋白质、酸性洗涤纤维表观消化率高于其余3组(P0.05),其他组间消化率无显著差异;3 g/kg复合菌组犊牛血清白蛋白含量高于其他各组(P0.05),其他指标无显著差异。由此分析,4月龄犊牛日粮中复合益生菌的适宜添加量为3 g/kg,可显著提高断奶期犊牛日增重、饲料转化效率,增强免疫力。     

不同蛋白质水平饲粮对3~4月龄中国荷斯坦犊牛生长性能及消化率的影响

试验旨在研究3~4月龄中国荷斯坦犊牛的适宜饲粮蛋白水平。选取24头65日龄犊牛随机分为3组,分别饲喂19%、21%和23%3种蛋白水平饲粮,分析饲粮蛋白水平对犊牛生长性能、血液生化指标和消化率的影响。结果表明:饲喂19%、21%和23%3种蛋白水平饲粮后,试验全组的日增重分别为(1.19±0.16)kg/d、(1.23±0.16)kg/d、(1.24±0.13)kg/d,组间差异不显著;饲粮蛋白水平对犊牛体斜长显著影响(P<0.05)。血清尿素氮,甘油三酯和游离脂肪酸含量随着饲粮水平的增加而显著提高(P<0.01);饲粮蛋白质水平对总蛋白,白蛋白,乳酸脱氢酶,碱性磷酸酶,谷草转氨酶,总胆固醇,高密度脂蛋白胆固醇,低密度脂蛋白胆固醇,葡萄糖等的影响不显著。粗蛋白、干物质粗脂肪和中性洗涤纤维消化率随饲粮蛋白质水平提高而减低。综合试验犊牛日增重、体尺指标、血液指标和营养物质消化率等各方面的因素,在本试验条件下19%蛋白水平的饲粮对于3~4月龄犊牛最为合适。     

日粮能量水平对体质量500 kg荷斯坦阉牛生产性能和血清生化指标的影响

本试验旨在研究日粮综合净能(NEmf)水平对体质量500 kg荷斯坦阉牛增重、养分消化率和血液生化指标的影响。选择健康、体况良好、平均体质量为(501.47±40.09) kg的13月龄荷斯坦阉牛60头,采用完全随机设计,试验分为3组,每组20个重复,每个重复1头牛。试验组为低能量组(LE组,5.89 MJ/kg NEmf)、中能量组(ME组,6.10 MJ/kg NEmf)和高能量组(HE组,6.30 MJ/kg NEmf)。各试验组粗蛋白质(CP)水平相同。预试期10 d,正试期87 d。结果显示,提高日粮能量水平对荷斯坦阉牛的平均日增体质量(ADG)无显著性影响(P0.05),但显著降低料重比(P0.05)和日粮中干物质、脂肪、中性洗涤纤维的表观消化率(P0.01);随着日粮能量水平的增加,荷斯坦阉牛血液的GLU和UN无显著性变化(P0.05),但显著提高了血液中LPL的活性(P0.05),与LE组相比,ME组LDL含量显著提高(P0.01),但与HE组无显著性差异(P0.05);日粮能量水平的增加对瘤胃pH、NH_3-N、VFA无显著性影响(P0.05);提高日粮能量水平增加了养殖收益,ME组最高,较LE组和HE组分别增加6.94%和3.10%。结果表明,在本试验条件下,500～600 kg荷斯坦阉牛日粮CP在11.5%时,适宜能量水平为6.10 MJ/kg。     

不同营养水平代乳料对奶公犊生长性能及血液生化指标的影响

选用40头健康、体质量及出生日期相近的荷斯坦奶公犊,按体质量随机分为4组(每组10头),进行为期120d的生长育肥试验。不同处理组代乳料的营养水平为:Ⅰ组(22.00%CP,16.00 MJ/kg DE),Ⅱ组(20.00%CP,16.00 MJ/kg DE),Ⅲ组(22.00%CP,15.00 MJ/kg DE),Ⅳ组(20.00%CP,15.00 MJ/kg DE)。结果表明,Ⅰ组犊牛的日增重显著高于其他3组,比Ⅱ组、Ⅲ组和Ⅳ组分别提高了11.63%(P0.01),6.67%(P0.01)和5.49%(P0.01)。代乳料的蛋白水平对犊牛试验末体质量和日增重影响显著,蛋白质水平为22.00%的代乳料组试验牛的试验末体质量和日增重比20.00%代乳料组分别提高了3.29%(P0.05)和5.62%(P0.01)。代乳料的消化能(DE)水平显著影响犊牛的干物质采食量(DMI),随DE水平的提高而显著降低,与15 MJ/kg DE水平代乳料组相比,16 MJ/kg DE水平代乳料组犊牛的DMI降低了2.90%(P0.01);代乳料的蛋白水平对奶公犊60d和120d粗蛋白质和粗脂肪的消化率影响显著(P0.05),蛋白质水平为22.00%的代乳料组犊牛60d和120d粗蛋白质的消化率比20.00%代乳料组分别提高了3.49%(P0.05)和4.57%(P0.05),粗脂肪的消化率分别提高了6.67%(P0.05)和3.80%(P0.05);蛋白质水平为22.00%的代乳料组试验牛120d血清中BUN、TP和T3的含量比20.00%代乳料组分别提高了21.61%(P0.05),4.36%(P0.05)和5.79%(P0.05)。综上所述,在本试验条件下,Ⅰ组犊牛的日增重、试验末体质量和营养物质消化率最高,建议0~4月龄奶公犊日粮适宜的DE为16.00 MJ/kg,CP为22.00%。     

营养水平对肉犊牛营养物质消化率和血清指标的影响

研究不同能量、蛋白质水平的代乳品对南方地区哺乳期肉用犊牛营养物质消化和血清指标的影响,进而确立代乳品能量和蛋白质参数,为南方地区肉犊牛的饲料配制提供数据支持。采用2×2因子设计,犊牛代乳品的能量水平为16、14 MJ/kg,粗蛋白水平为25%、22%,共计4种。选取新生犊牛40头,21日龄断母乳并根据日龄和体重一致原则分为4个处理组,每组10头犊牛,分别饲喂上述4种代乳品,于77~85日龄进行消化试验并静脉采集血液。结果显示相同能量水平,犊牛对代乳品中粗脂肪和钙的表观消化率随粗蛋白水平的升高而提高(P0.05);较低粗蛋白水平代乳品,随其能量水平的升高,粗蛋白消化率显著提升(P0.05);低能低蛋白组(DE:14 MJ/kg,CP:22%)营养物质消化率略小于其它各组。饲喂低能量水平代乳品时,随其粗蛋白水平的升高,犊牛血清中尿素氮含量显著降低(P0.05);而饲喂高能量水平代乳品时,随其粗蛋白水平的升高,犊牛血清谷草转氨酶含量显著提高(P0.05);代乳品能量和粗蛋白水平对犊牛其它血清指标均无显著影响(P0.05)。高能量水平(DE:16 MJ/kg)有助于犊牛粗蛋白质消化吸收,高蛋白水平(CP:25%)有助于犊牛对粗脂肪和钙的利用,低能低蛋白水平(DE:14 MJ/kg,CP:22%)日粮不利于犊牛营养物质消化吸收。     

代乳粉中添加白藜芦醇和血根碱对0～2月龄荷斯坦犊牛营养物质消化及瘤胃发酵的影响

本试验旨在研究白藜芦醇(RES)和血根碱(SAG)对0~2月龄荷斯坦犊牛营养物质消化、瘤胃发酵的影响。选用5日龄、体重为(42.22±3.49)kg的54头荷斯坦母犊牛,随机分成3个处理组,每个处理18头。5~11日龄过渡期使用相同代乳粉在犊牛岛进行单独饲喂,此后转移至牛圈进行分栏饲养。对照组犊牛单独饲喂代乳粉(MR);SAG组犊牛在MR中按每千克体重添加0.05 mg SAG;RES组犊牛在MR中按每千克体重添加4 mg RES。试验期为58 d。在犊牛5、56日龄测定体重,28、56日龄采集瘤胃液,57~63日龄时进行消化试验。结果表明:3组犊牛干物质采食量、日增重、饲料转化率无显著差异(P0.05);RES和SAG对犊牛饲粮中干物质、粗蛋白质、有机物、钙、磷、中性洗涤纤维和酸性洗涤纤维表观消化率的影响差异均不显著(P0.05);56日龄,SAG组犊牛瘤胃乙酸浓度显著高于对照组(P0.05),RES组犊牛瘤胃液乙酸/丙酸显著高于对照组(P0.05)。综上所述,代乳粉中添加RES和SAG对0~2月龄犊牛采食量具有一定促进作用,但对日粮养分消化影响不明显,对瘤胃发酵指标没有不良影响。     

不同粗饲料对断奶荷斯坦公犊牛生长发育、消化代谢和血清生化指标的影响

本试验旨在研究不同粗饲料对断奶荷斯坦公犊牛生长发育、消化代谢和血清生化指标的影响。选取54头健康断奶荷斯坦公犊牛[(70±3)日龄、(77.50±5.07) kg],随机分为3个组,每组18头。3组饲粮粗饲料来源分别为花生秧(PV组)、燕麦干草(OH组)以及苜蓿干草+燕麦干草组合(苜蓿干草∶燕麦干草=1∶1,AO组)。预试期7 d,正试期60 d。正试期内每日测定犊牛的采食量,每15 d测量犊牛体重和体尺指标,在正试期第60天各组随机选择6头犊牛颈静脉采集血液用于测定血清生化指标,在饲养试验结束后进行2期消化代谢试验。结果显示:1)PV组和AO组犊牛试验全期的平均日采食量、末重、平均日增重均显著高于OH组(P0.05),料重比以PV组最低。2)在第30天时,PV组和AO组犊牛胸围显著高于OH组(P0.05);在第60天时,PV组犊牛体高和胸围显著高于OH组(P0.05)。3) PV组犊牛的干物质表观消化率和氮的生物学价值显著高于OH组(P0.05);同时,PV组犊牛的有机物和钙的表观消化率、消化能、代谢能、甲烷能、吸收氮和沉积氮也均显著高于OH组(P0.05)。4) PV组犊牛血清中总胆固醇、高密度脂蛋白、低密度脂蛋白、葡萄糖含量显著高于OH组和AO组(P0.05),且其血清尿素氮含量显著低于OH组和AO组(P0.05)。5) PV组的经济效益最高,花生秧的单价最低,使得PV组的粗饲料增重成本较OH组和AO组显著降低(P0.05),增加了利润空间。由此得出,以花生秧为断奶荷斯坦犊牛饲粮粗饲料来源能够满足其对营养物质的需要,并使其具有更高的平均日增重和饲料利用率,还可降低饲料成本,同时对犊牛整体健康无负面影响,因此,花生秧可作为断奶荷斯坦犊牛饲粮的优质粗饲料来源。     

不同月龄生长公牛日粮营养物质消化规律的研究

本试验选用3头6月龄左右断奶中国荷斯坦公牛,在试验全程喂以相对稳定的日粮,从2003年11月1日开始,到2004年6月20日结束,用以测定中国荷斯坦生长公牛在不同生长期对饲粮中各营养成分的代谢情况.试验结果表明：日粮中的DM、OM、NDF、ADF、淀粉和粗蛋白质的表观消化率随着生长犊牛的月龄的增加而增加（P＜0.05）;并且9月龄以后,DM、OM、NDF、ADF和粗蛋白质的表观消化率增长不明显（P＞0.05）,淀粉的表观消化率则在11月龄以后增长不明显（P＞0.05）.氮的净吸收率随着生长犊牛的月龄的增加而下降（P＜0.05）,且在9月龄以后下降不明显（P＞0.05）.     

Feeding different dietary protein to energy ratios to Holstein heifers: effects on growth performance,blood metabolites and rumen fermentation parameters

Eighteen Chinese Holstein heifers average age 230 ± 14 days were allocated to 1 of 3 dietary crude protein (CP) to metabolizable energy (ME) ratios to examine the effects on growth performance, blood metabolites and rumen fermentation parameters with 90‐days experiment. Three different dietary CP:ME ratios were targeted based on the formulation of dietary CP contents of 10.85%, 12.78% and 14.63% on dry matter (DM) basis with similar ME contents (10.42 MJ/kg DM), which were categorized as low, medium and high dietary CP:ME ratios. The actual CP:ME ratios obtained in this study significantly increased from low to high CP:ME ratio groups with a value of 10.59, 11.83 and 13.38 g/MJ respectively. Elevated CP:ME ratios significantly increased CP intake (kg/day) and feed efficiency (FE) which was defined as dry matter intake as a proportion of average daily gain (ADG), whereas little difference was observed in body weight (kg), ADG (kg/day), DM intake (kg/day) and ME intake (MJ/day) among the three different CP:ME ratio groups. Increasing dietary CP to ME ratios significantly increased CP digestibility, whereas digestibility of DM and gross energy remained constant in the current experiment. Blood urea nitrogen and insulin‐like growth factor‐1 linearly increased with increasing dietary CP:ME ratios. There was significantly dietary treatment effect on rumen fermentation parameters including acetate, propionate, butyrate and total volatile fatty acids. Therefore, this study indicated that increasing dietary CP levels with similar energy content contributed to increased protein intake and its digestibility, as well as FE. Holstein heifers between 200 and 341 kg subjected to 13.38 dietary CP:ME ratio showed improved feed efficiency, nutrient digestibility, some blood metabolites and rumen fermentation characteristics for 0.90 kg/day rate of gain.     

不同代乳品及饲喂方式对荷斯坦奶公犊生产犊牛白肉影响的研究

为研究代乳粉(主要含乳类制品)液态饲喂和代乳料(主要含植物类饲料等)干喂对荷斯坦奶公犊生产犊牛白肉的影响,试验选用20头健康无病、体重和出生日期相近的荷斯坦奶公犊,随机分为2组,每组10头,进行了120 d的生长育肥试验。Ⅰ组饲喂市售的代乳粉(粗蛋白质22%,粗脂肪16%);Ⅱ组饲喂配制的代乳料(粗蛋白质22%,消化能16 MJ/kg)。结果表明:①Ⅱ组犊牛0~90 d平均日增重高于Ⅰ组犊牛,91~120 d平均日增重显著低于Ⅰ组犊牛(P< 0.05),但两组犊牛0~120 d平均日增重和试验末重均无显著差异(P> 0.05)。②不同代乳品及饲喂方式对奶公犊营养物质表观消化率均无显著影响(P> 0.05)。③Ⅰ组犊牛的胴体重、屠宰率和眼肌面积均显著高于Ⅱ组犊牛(P< 0.05),分别比Ⅱ组高11.88%、11.04%和8.12%,但两组间的胴体产肉率无显著差异(P> 0.05);两组犊牛背最长肌的pH、剪切力、蒸煮损失和肉色均无显著差异(P> 0.05),但Ⅰ组犊牛的失水率比Ⅱ组犊牛高20.83%(P< 0.01);Ⅰ组犊牛背最长肌中粗脂肪含量极显著高于Ⅱ组犊牛(P< 0.01),但两组犊牛背最长肌中水分、粗蛋白质、粗灰分、钙、磷和铁的含量均无显著差异(P> 0.05)。④Ⅱ组犊牛的饲养成本比Ⅰ组降低45.38%。综上所述,饲喂代乳料的犊牛可获得与饲喂代乳粉犊牛相似的生长性能和肉品质,显著降低饲养成本。     

Effect of crabgrass (Digitaria ciliaris) hay harvest interval on forage quality and performance of growing calves fed mixed diets

Twelve 0.81-ha crabgrass (Digitaria ciliaris [Retz.] Koel.) hay fields were harvested at 21, 35, and 49 d of regrowth (average phonological growth stage of 30, 51, and 56, respectively). Increased harvest interval exhibited a linear decrease (P < 0.01) in CP (14.1, 13.7, and 10.6% of DM, respectively) and increase (P < 0.01) in NDF (65.3, 70.6, and 70.2% of DM, respectively) and ADF (35.7, 38.9, and 42.7% of DM, respectively). Hays were incorporated into 3 diets that contained 20% (DM basis) crabgrass hay, ground corn (33%), and soybean hulls (32%). Diets contained 14.4, 14.4, and 13.6% CP; 1.83, 1.72, and 1.81 Mcal of NE(m)/kg; and 1.21, 1.10, and 1.17 Mcal of NE(g)/kg; respectively. Diets were fed to beef calves in 12 pens at a rate of 2.3% (DM basis) of BW in 1 experiment (n = 120, initial BW 210 +/- 4.4 kg) and ad libitum in another experiment (n = 60, initial BW 207 +/- 4.4 kg). To measure passage rate of the hay and concentrate portions of the diets, 12 heifer calves (BW = 145 +/- 4.5 kg) were individually fed at 2.3% of BW for 14 d and dosed with Dy-labeled soybean hulls and Yb-labeled hay. In situ DM digestibility of the hays and diets were determined using 3 ruminally cannulated steers (BW = 584 +/- 10.4 kg). Harvest interval did not affect (P > or = 0.11) ADG of limit-fed calves during the diet acclimation or growing phases (average 0.32 and 0.80 kg, respectively) or ADG of calves fed ad libitum (average 1.21 kg). Dry matter intake of calves fed ad libitum averaged 7.9 kg/d (3.28% of BW) and was not affected (P > or = 0.22) by harvest interval. Gain:feed was not affected (P > or = 0.20) by harvest interval (0.13 and 0.15 for limit-fed and ad libitum-fed calves, respectively). Increased harvest interval linearly increased (P < 0.01) ruminal retention time of the hay and tended (P = 0.06) to linearly increase ruminal retention time of the concentrate portions of the diet. Harvest interval linearly decreased (P < or = 0.05) the extent of degradability and effective degradability of DM and NDF of hays, but DM disappearance of the total diet did not differ (P > or = 0.35). In the conditions of this study, increasing harvest interval of crabgrass hay from 21 to 49 d had no deleterious impact on animal performance or efficiency of gain when fed to growing calves in a high-concentrate mixture.     

Study on Production of White Veal with Holstein Bull Calves Fed on Different Milk Replacer and Feeding Methods

The objective of this experiment was to study the effects of production of white veal with Holstein bull calves fed on the liquid milk replacer (containing mainly dairy products) feeding and the dry milk replacer (containing mainly plant diet, etc)feeding.20 healthy male calves with similar birth date and body weight were selected, and randomly divided into two groups (10 calves per group), for a period of 120 d white beef production fattening test.GroupⅠfed with milk replacer (commercial, 22% CP, 16% EE), groupⅡ fed with milk replacer (formulated, 22% CP, 16 MJ/kg DE).The results showed as follows:① 0 to 90 d ADG of group Ⅱ were higher than groupⅠ, 91 to 120 d ADG of group Ⅱ were significantly lower than groupⅠ (P< 0.05), but there were no significant differences in 0 to 120 d ADG and 120 d weight between two groups (P> 0.05).② There were no significant differences in the nutrient apparent digestibility of Holstein bull calves with different milk replacer and feeding methods (P> 0.05).③ Carcass weight, dressing percentage and eye muscle area of groupⅠcalves were significantly higher than those of group Ⅱ (P< 0.05), increased by 11.88%, 11.04% and 8.12%, respectively, but there was no significant difference in carcass meat production rate between two groups (P> 0.05).There was no significant differences in pH, shear force, cooking lose and meat color of longissimus between two groups (P> 0.05), but compared with group Ⅱ, the water lose rate of groupⅠincreased by 20.83% (P< 0.01).The content of EE of groupⅠwas significantly higher than group Ⅱ (P< 0.01), but there were no significant differences in the contents of moisture, CP, Ash, Ca, P and Fe of longissimus between two groups (P> 0.05).④Compared with groupⅠ, the feed cost of group Ⅱ was reduced by 45.38%.In summary, the growth performance and meat quality of two groups calves were similar, feeding cost was reduced significantly.     

Nutrient digestibility of extruded canola meal in ileal-cannulated growing pigs and effects of its feeding on diet nutrient digestibility and growth performance in weaned pigs

Canola meal (CM) contains less crude protein (CP) and more fiber and anti-nutritional factors such as glucosinolates than soybean meal (SBM) and consequently has a lower nutrient digestibility. Therefore, processing strategies that may increase the feeding value of CM warrant study. In two experiments, the effects of extrusion of Brassica napus CM on apparent (AID) and standardized ileal digestibility (SID) of amino acids (AA), apparent total tract digestibility (ATTD) of gross energy (GE) in growing pigs, and growth performance and diet digestibility in weaned pigs were assessed. Solvent-extracted CM was extruded using a single-screw extruder at three screw speeds: 250 (CM-250), 350 (CM-350), or 450 (CM-450) rpm. In exp. 1, in a double 4 × 4 Latin square, eight ileal-cannulated barrows (initial body weight [BW], 68.1 kg) were fed corn starch-based diets containing 50% CM or extruded CM. The CM sample contained 43.2% CP, 33.2% total dietary fiber (TDF), and 8.9 µmol of total glucosinolates/g on a dry matter (DM) basis. Extrusion increased (P < 0.05) the AID of CP, reduced (P < 0.05) apparent hindgut fermentation of CP, and decreased (P < 0.05) predicted net energy (NE) value of diets. Extrusion increased diet AID and CM SID of most indispensable AA by 3.1 to 5.3%-units. In exp. 2, 200 weaned pigs (initial BW, 8.3 kg) were fed diets containing 20% SBM, CM, or extruded CM starting 2 wk postweaning for 3 wk. The CM sample contained 42.7% CP, 28.3% TDF, and 5.3 µmol total glucosinolates/g DM. Wheat-based diets provided 2.3 Mcal NE/kg and 5.1 g SID Lys/Mcal NE. Dietary inclusion of extruded CM replacing SBM decreased (P < 0.05) diet ATTD of DM, GE and CP, and DE value. Average daily feed intake, average daily gain (ADG), and gain:feed (G:F) of pigs did not differ between extruded CM and SBM diets and were not affected by extrusion, but increasing extruder screw speed linearly increased (P < 0.05) ADG for day 1 to 7 and G:F for the entire trial. In conclusion, extrusion increased diet AID and CM SID of AA but not DE and predicted NE values of CM. However, increasing extruder speed did not further increase the SID of most of the AA of CM in growing pigs. Dietary inclusion of 20% CM or extruded CM did not affect the growth performance in weaned pigs.     

Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of Angus and Holstein steers

Twelve Angus (237 +/- 13 kg) and twelve Holstein (235 +/- 15 kg) steers were used to determine whether corn silage-based diets with different NDF levels influence DMI to a similar extent in Angus and Holstein steers and as body weight of the steers increase. Steers were randomly assigned to individual slatted-floor pens and used in a crossover design consisting of six 14-d periods. Experimental diets contained corn silage from a normal hybrid (low-fiber; LF) and its male-sterile counterpart (high-fiber; HF) and were alternated each period. The LF and HF diets contained 33.8 and 50.8% NDF, respectively. The HF diet decreased (P < 0.01) overall steer mean DMI 14.0% relative to LF, with mean differences increasing as steers increased in BW (P < 0.01). Feeding the HF diet also reduced ADG by an average of 13.8% relative to the LF diet (P < 0.01). Holstein steers consumed 14.4% more DM and gained 14.3% faster (P < 0.01) than Angus steers. There was a fiber level x breed-type interaction (P = 0.08) for efficiency of gain. Angus steers receiving the HF diet had greater efficiency of gain than Angus steers consuming the LF diet; however, Holstein steers consuming the LF diet had greater efficiency of gain than those receiving the HF diet. The HF treatment reduced total-tract digestibility of DM and GE by 4.6 and 4.5%, respectively (P < 0.01), and decreased DE intake by 20.5% (P < 0.01) but increased apparent totaltract digestibility of NDF and ADF (9.4 and 8.4%, respectively; P < 0.01). Holstein steers had similar digestibility of DM and GE (P > 0.10) but had greater DE intake (P < 0.01) compared to Angus steers. There were fiber level x breed-type interactions for total-tract digestibility of NDF and ADF (P < 0.06). The difference in DM digestibility was negatively associated with the difference in DMI (r2 = 0.23; P < 0.01) for LF minus HF within Angus steers, but not within Holstein steers (P = 0.42). Total-tract digestibility of NDF and ADF was 4.1 and 3.4% lower for the HF diet but was only 1.1 and 0.6% lower for the LF diet when fed to Holstein compared to Angus steers. Results from this trial demonstrate that high-NDF corn silage-based diets reduced intake of both Angus and Holstein steers, and this reduction in DMI continued as steers increased in BW from 235 to 330 kg. Breed differences were also noted for digestible energy intake as influenced by fiber level.     

日粮不同NDF/NFC水平对周岁后荷斯坦奶牛生产性能、营养物质消化率、瘤胃发酵特征和甲烷排放的影响

本试验研究了日粮中不同中性洗涤纤维/非纤维性碳水化合物（NDF/NFC）水平对周岁后荷斯坦奶牛生产性能、营养物质消化率、瘤胃发酵特征及甲烷产量的影响，并在此基础上建立了甲烷排放预测模型，旨在获得我国生产模型下的甲烷排放规律和甲烷转化因子，为提高奶牛能量利用效率、建立国家或区域性温室气体排放清单和探索减排策略提供科学依据和支撑。将45头体况良好，平均为15月龄的荷斯坦后备奶牛随机分为3组，每组15头牛：低日粮NDF/NFC组（NDF/NFC=0.60）、中日粮NDF/NFC组（NDF/NFC=0.75）和高日粮NDF/NFC组（NDF/NFC=0.90），试验期为70 d，包括14 d的预饲期和56 d的正试期。结果表明：1）提高日粮NDF/NFC水平显著降低了奶牛的干物质采食量、有机物采食量、平均日增重、干物质和粗蛋白的表观消化率（P<0.05）；2）提高日粮NDF/NFC水平显著增加了瘤胃内总挥发性脂肪酸产量、乙酸的相对含量和乙酸/丙酸比例（P<0.05），显著降低了丙酸的相对含量（P<0.05）；3）随着日粮NDF/NFC水平的提高，瘤胃甲烷和甲烷能产量、甲烷/代谢体重、甲烷/干物质采食量、甲烷/有机物采食量、甲烷/中性洗涤纤维采食量显著提高（P<0.05）。甲烷转化因子也随着日粮NDF/NFC水平的增加而显著提高（P<0.05）；4）基于体重、采食量、营养物质含量和NDF/NFC分别建立了甲烷预测模型，其中基于干物质采食量和中性洗涤纤维采食量建立的预测模型的决定系数最高（R²=0.77）。因此，提高日粮中NDF/NFC水平可显著降低周岁后荷斯坦奶牛的生产性能、营养物质消化率和瘤胃内丙酸的相对含量，可显著提高瘤胃甲烷产量和甲烷转化因子。     

Effects of dietary nonprotein nitrogen on performance, digestibility, ruminal characteristics, and microbial efficiency in crossbred steers

Two trials were conducted to evaluate the effects of dietary NPN levels on animal performance, diet digestibility, ruminal characteristics, and microbial efficiency. Experiment 1 was conducted with 24 Holstein x Nellore crossbred steers (350 +/- 20 kg of BW) distributed in 6 blocks to evaluate intake and digestibility of nutrients and performance. The diets consisted of 70% corn silage and 30% concentrate (DM basis) and were formulated to contain 12.5% CP (DM basis). Treatments consisted of 0, 15.5, 31, and 46.5% of dietary N as NPN. There were no treatment differences in the daily intakes of DM (P = 0.47), OM (P = 0.60), CP (P = 0.24), nonfiber carbohydrates (NFC; P = 0.74), or TDN (P = 0.63); however, NDF intake decreased linearly as NPN increased (P = 0.02). Additionally, no effects of NPN were observed on apparent total tract digestibility of DM (P = 0.50), OM (P = 0.53), NDF (P = 0.63), or NFC (P = 0.44). The apparent total tract digestibility of CP increased linearly (P = 0.01), but ADG (1.14 kg/d) was not influenced (P = 0.96) as NPN increased. In Exp. 2, 4 ruminally and abomasally cannulated steers (300 +/- 55 kg of BW) were fed the same diet used in Exp. 1 to evaluate the effects of NPN levels on intake and digestibility of nutrients, ruminal characteristics, and microbial efficiency. There were no differences in the daily intakes of DM (P = 0.22), OM (P = 0.17), CP (P = 0.31), NDF (P = 0.29), or TDN (P = 0.49). However, NFC intake increased linearly (P = 0.02), and there was a quadratic effect (P = 0.01) on intake of ether extract as NPN increased. Ruminal digestibility of CP increased linearly (P = 0.01) with the increase of dietary NPN. There were no differences (P >or= 0.28) in microbial protein synthesis and microbial efficiency among the treatments. The results of these trials suggest that dietary NPN levels (up to 46.5% of total N) can be fed to crossbred steers receiving corn silage-based diets without affecting their growth performance or ruminal protein synthesis.     

Evaluation of Feed Mixtures Amended with Processed Food Waste as Feedstuffs for Finishing Lambs

This study was undertaken to evaluate the acceptability, growth performance, and diet digestibility of feed mixtures containing food wastes that were further heat processed for growing-finishing lambs. The first experiment consisted of two feeding trials in which 36 lambs in each trial were fed 1) total mixed rations (TMR) containing extruded feed mixtures that were amended with pulped plate waste (PW) collected from university dining centers or 2) control TMR containing corn, soybean meal, and ground hay in Trial 1 (T1) or soybean hulls in Trial 2 (T2). On a DM basis, the treatment TMR in T1 contained 23.9% PW, and the treatment TMR in T2 contained 24.1% PW. The PW used in this study contained 37.5 ± 9.4% DM, 33.0 ± 8.2% CP, 14.7 ± 5.5% ether extract (EE), and 12.6 ± 5.2% ADF. During T1, lambs fed the control TMR (compared with lambs fed PW) had greater (P<0.05) ADG (299.6 ± 36.3 vs 259.0 ± 54.5 g), less (P<0.05) ADFI (811.1 ± 64.0 vs 2,113.6 ± 748.6 g), and greater (P<0.05) gain:feed (0.37:1 vs 0.24:1 g). During T2, no differences between the control lambs and lambs fed PW were observed in terms of ADG (mean = 231.6 ± 40.9 g), ADFI (mean = 1,766.1 ± 168.0 g), and gain:feed (mean = 0.12:1 g). The second experiment consisted of three digestibility trials (T3, T4, and T5). In T3, 24 wethers were fed an extruded mixture (EF) containing soybean hulls, rolled shelled corn, and 24.5% pulped PW (DM basis). In T4, 28 wethers were fed a dehydrated mixture (DF) containing wheat middlings and ground food waste originating from retail groceries in a 75:25 (DM basis). In T5, 28 wethers were fed an extruded mixture (EFM) containing soybean hulls, rolled corn, and 42.3% pulped PW (DM basis). Apparent DE of EF was determined to be 3.22 ± 1.50 Mcal/kg. Apparent digestibility coefficients of EF were 54.50 ± 2.68% DM, 42.60 ± 4.39% ADF, 60.30 ± 15.68% CP, and 76.23 ± 3.77%EE. Apparent DE of DF was determined to be 3.17 ± 0.24 Mcal/kg. Apparent digestibility coefficients of DF were 64.98 ± 4.76% DM, 74.99 ± 4.91%protein, 15.70 ± 10.84% ADF, and 79.39 ± 5.07 EE. Apparent DE of EFM was determined to be 2.66 ± 0.18 Mcal/kg. The EFM apparent digestibility coefficients were 54.95 ± 4.16% DM, 62.61 ± 7.25% CP, 27.21 ± 7.77% ADF, and 79.78 ± 6.67% EE. This study indicates that amending traditional diets with dehydrated or extruded mixtures containing food waste is a practical processing method for including food wastes in sheep diets. However, acceptability of these diets by individual sheep may vary, and inconsistent growth performance levels and feed efficiencies may occur.     

Influence of fish meal and supplemental fat on performance of finishing steers exposed to moderate or high ambient temperatures.

Ninety-six Hereford x Angus steers (mean initial BW = 295 kg) were used in two growth experiments conducted at moderate and high ambient temperatures (AT), 48 steers per AT. Within each AT, calves were assigned to six dietary treatments consisting of a basal diet (approximately 60% corn and 20% grass hay) supplemented with either 0, 2.5, or 5% fat and with either soybean meal (SBM) or Menhaden fish meal (FM) included at levels such that a ratio of 16.3 kcal of NEm per kilogram of CP was maintained. Blood and ruminal fluid were collected 40 d before slaughter. During the final 28 d of the moderate AT experiment, apparent digestibility of dietary components was measured in four individually fed steers from each dietary treatment. Steer ADG was not affected by fat, and DMI and efficiency of gain were not affected (P > .10) by treatment. Average daily gain was lower for steers fed FM than for those fed SBM at moderate AT but higher at high AT (CP source x AT interaction; P < .05). Ruminal ratio of acetate to propionate declined linearly with increasing fat at moderate AT but was not affected by fat at high AT (fat x AT interaction trend; P = .08). Plasma urea N concentration increased linearly (P < .05) with increasing fat and was higher (P < .05) in steers kept at high than in those kept at moderate AT. Although apparent digestibility was not altered in steers fed FM, DM and NDF (P < .05) and ADF (P = .07) digestibility decreased with increasing fat in steers fed SBM (CP source x fat interaction).(ABSTRACT TRUNCATED AT 250 WORDS)