饲粮中性洗涤纤维水平对塔里木马鹿瘤胃发酵参数、血清生化指标、食糜外流速度及采食反刍规律的影响

本试验旨在探究饲粮中性洗涤纤维（NDF）水平对塔里木马鹿瘤胃发酵参数、血清生化指标、食糜外流速度和采食反刍规律的影响。选择体况接近、年龄相同的雌性塔里木马鹿5头，采用5×5拉丁方试验设计，分别饲喂NDF水平为47%、42%、37%、32%和27%的试验饲粮。每个试验期21 d，其中预试期15 d，正试期6 d。结果表明：1)27%NDF水平组瘤胃pH显著低于37%、42%和47%NDF水平组（P<0.05）,27%NDF水平组瘤胃氨态氮含量显著高于37%、42%和47%NDF水平组（P<0.05）,27%NDF水平组瘤胃乙酸含量极显著低于42%和47%NDF水平组（P<0.01）,47%NDF水平组瘤胃丙酸和总挥发性脂肪酸含量显著或极显著低于其他各组（P<0.05或P<0.01）。2)27%和32%NDF水平组血清尿素氮（UN）和葡萄糖（GLU）含量显著高于42%和47%NDF水平组（P<0.05）。3）随着饲粮NDF水平的降低，食糜外流速度降低，但各组之间差异不显著（P>0.05）。4) 42%和47%NDF水平组反刍时间、反刍周期食团数显著...     

日粮添加过瘤胃氨基酸对高产奶牛生产性能、乳成分和经济效益的影响

试验旨在研究日粮添加过瘤胃蛋氨酸和过瘤胃赖氨酸对高产奶牛生产性能、乳成分及经济效益的影响。按照胎次、产奶日期、日产奶量一致的原则,选择处于泌乳高峰期的健康中国荷斯坦奶牛96头,随机分为对照组和试验组,每组48头牛,每头牛1个重复。对照组饲喂基础日粮,试验组饲喂基础日粮+过瘤胃氨基酸[过瘤胃蛋氨酸添加量20 g/(头·d);过瘤胃赖氨酸添加量27 g/(头·d)]。预试期7 d,正试期30 d。结果表明:①日粮添加过瘤胃蛋氨酸和过瘤胃赖氨酸极显著提高奶牛日产奶量3.63%(P0.01),极显著提高饲料转化率4.49%(P0.01)。②日粮添加过瘤胃蛋氨酸和过瘤胃赖氨酸极显著降低尿素氮含量26.92%(P0.01),对乳脂率、乳蛋白率、体细胞数无显著影响(P0.05)。③与对照组相比,试验组奶牛经济效益增加2.30元/(头·d)。在本试验条件下,日粮添加过瘤胃蛋氨酸和过瘤胃赖氨酸能够提高高产奶牛产奶量,提高饲料转化率,提高经济效益。     

前花青素对断奶仔猪生长性能和血清抗氧化、免疫及生化指标的影响

本试验旨在研究饲粮中添加前花青素对断奶仔猪生长性能和血清抗氧化、免疫及生化指标的影响。选取平均23日龄的断奶仔猪120头,随机分成4组(对照组及试验Ⅰ、Ⅱ和Ⅲ组),每组3个重复,每个重复10头。对照组饲喂基础饲粮,试验组分别在基础饲粮中添加50、100和150 mg/kg前花青素。试验预试期7 d,正试期30 d。结果表明:1)与对照组相比,试验Ⅰ、Ⅱ组仔猪平均日增重显著或极显著提高(P0.05或P0.01);各试验组仔猪腹泻率均极显著降低(P0.01),且试验Ⅱ组腹泻率最低。2)与对照组相比,各试验组血清总抗氧化能力显著提高(P0.05),其中试验Ⅱ组显著高于试验Ⅰ、Ⅲ组(P0.05);各试验组血清丙二醛含量显著降低、超氧化物歧化酶活性显著提高(P0.05),且3组间差异不显著(P0.05)。3)与对照组相比,试验Ⅱ组血清免疫球蛋白G和补体3含量显著提高(P0.05);各试验组血清补体4含量显著提高(P0.05),且3个试验组间差异不显著(P0.05)。4)与对照组相比,各试验组血清甘油三酯和尿素氮含量显著或极显著降低(P0.05或P0.01),试验Ⅱ组血清白蛋白含量极显著提高(P0.01),其他血清生化指标各组间差异不显著(P0.05)。结果提示:在断奶仔猪饲粮中添加前花青素可提高仔猪的日增重,降低腹泻率,改善血清抗氧化能力并提高免疫力,添加量以100 mg/kg为宜。     

饲粮核黄素添加水平对生长獭兔生长性能、毛皮质量、血液指标及抗氧化功能的影响

本试验旨在研究饲粮核黄素添加水平对3~5月龄生长獭兔生长性能、毛皮质量、血液指标及抗氧化功能的影响。选取体重相近、健康状况良好的3月龄獭兔160只,随机分成4组,每组40个重复,每个重复1只。对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮中添加3、6和12 mg/kg核黄素的试验饲粮。预试期7 d,正试期53 d。结果表明:饲粮核黄素添加水平对生长獭兔料重比、平均日增重、平均日采食量均无显著影响(P0.05),对毛皮厚度、被毛长度无显著影响(P0.05),但是对毛皮面积、毛皮重量有显著或极显著影响(P0.05或P0.01)。饲粮核黄素添加水平对血清胆固醇含量有显著影响(P0.05),而对血清总蛋白、白蛋白、甘油三酯、尿素氮、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇含量均无显著影响(P0.05)。6 mg/kg添加组血清和肝脏谷胱甘肽过氧化物酶活性极显著高于对照组(P0.01)。饲粮核黄素添加水平对血清和肝脏总超氧化物歧化酶活性、丙二醛含量以及肝脏总抗氧化能力无显著影响(P0.05)。结果表明,生长獭兔的饲粮核黄素添加水平为6 mg/kg(饲粮核黄素实测含量为8.35 mg/kg)时能显著提高毛皮品质和机体抗氧化能力。     

不同粗饲料来源饲粮对湖羊生长性能、瘤胃发酵及血清生化指标的影响

本试验在相同能量和蛋白质水平下,研究了不同粗饲料来源的饲粮对湖羊生长性能、瘤胃发酵功能及血清生化指标的影响。选用体况良好、体重相近的湖羊18只,随机分为3组,每组6只。在相同能量和蛋白质水平饲粮条件下,分别饲喂以花生藤(PV组)、豆秸(BS组)和甘蔗渣(SM组)作为单一粗饲料配制3种不同粗饲料来源的饲粮。试验期60 d,其中预试期15 d,正试期45 d。结果显示:1)PV组平均日增重显著高于BS组和SM组(P0.05)。2)SM组湖羊瘤胃液乙酸、丁酸、总挥发性脂肪酸含量及乙酸/丙酸显著或极显著低于其他2组(P0.05或P0.01);丙酸含量在9 h显著或极显著高于其他2组(P0.05或P0.01),但在24 h组间差异不显著(P0.05)。3)SM组的血清中尿素氮含量显著高于PV组(P0.05),肌酐含量显著高于BS组(P0.05)。结果提示,在相同能量和蛋白质水平饲粮条件下,相比于豆秸和甘蔗渣,以花生藤为粗饲料来源的饲粮能够改善湖羊生长发育及瘤胃发酵功能,提高氮的利用率,从而减少精饲料的补充量。     

不同铜源及铜水平对育成期蓝狐生长性能、营养物质消化率及血清指标的影响

本试验旨在研究饲粮中不同铜源及铜水平对育成期蓝狐生长性能、营养物质消化率及血清指标的影响。试验选择55日龄健康蓝狐100只,随机分成5个组,每组20个重复,每个重复1只蓝狐。5组蓝狐分别饲喂在基础饲粮中添加0、50、100 mg/kg(以铜计)的五水硫酸铜(CuSO_4·5H_2O)或蛋氨酸铜(Met-Cu)的试验饲粮,2种铜源共用0添加组为对照组。预试期为7 d,正试期为60 d。结果表明:1)饲粮铜水平对育成期蓝狐平均日增重有极显著影响(P0.01),对育成期蓝狐料重比有显著影响(P0.05)。饲粮铜源对育成期蓝狐平均日采食量、平均日增重和料重比均无显著影响(P0.05)。2)饲粮铜水平对育成期蓝狐粗蛋白质消化率和粪铜含量有极显著影响(P0.01),对干物质消化率、粗脂肪消化率有显著影响(P0.05)。饲粮铜源对育成期蓝狐粪铜含量有显著影响(P0.05),蛋氨酸铜组的粪铜含量显著低于硫酸铜组(P0.05);饲粮铜源对育成期蓝狐干物质消化率、粗脂肪消化率、粗蛋白质消化率和氮沉积均无显著影响(P0.05)。3)饲粮铜源及铜水平对育成期蓝狐血清尿素氮含量有极显著影响(P0.01),50、100 mg/kg铜添加组的血清尿素氮含量极显著高于对照组(P0.01),蛋氨酸铜组的血清尿素氮含量极显著高于硫酸铜组(P0.01)。饲粮铜源及铜水平对育成期蓝狐血清总蛋白、白蛋白、球蛋白、铜、铁含量及天冬氨酸转氨酶、丙氨酸转氨酶活性均无显著影响(P0.05)。由此可见,育成期蓝狐的饲粮中添加蛋氨酸铜可以获得与硫酸铜相似的促生长效果,此外,蛋氨酸铜的利用率更高,环境排放低,是蓝狐饲粮更高效、更环保的有机铜源。     

牛至油对断奶仔猪生长性能、血清激素指标及小肠组织胰岛素样生长因子-Ⅰ含量的影响

本试验旨在研究饲粮中添加牛至油对断奶仔猪生长性能、血清激素指标及小肠组织胰岛素样生长因子-Ⅰ(IGF-Ⅰ)含量的影响。选取体重相近的25日龄断奶"大白×长白"二元杂交仔猪120头,随机分为4组,每组3个重复,每个重复10头猪。对照组饲喂基础饲粮,3个试验组分别在基础饲粮中添加300、500、800 mg/kg牛至油。预试期为5 d,正试期为30 d。结果表明,与对照组相比,3个试验组断奶仔猪第1~30天的平均日采食量均极显著提高(P0.01),平均日增重显著或极显著提高(P0.05或P0.01),腹泻率极显著降低(P0.01);3个试验组断奶仔猪第15天的血清IGF-Ⅰ含量显著提高(P0.05),第30天的血清IGF-Ⅰ含量极显著提高(P0.01);3个试验组断奶仔猪十二指肠和回肠IGF-Ⅰ含量极显著提高(P0.01)。由此可见,饲粮中添加牛至油可以提高断奶仔猪血清和小肠组织IGF-Ⅰ含量,促进断奶仔猪生长。     

Low Protein Diet Supplemented with Urea Affects Digestion and Metabolism of Meat Rabbits

本试验旨在研究低蛋白质饲粮中添加尿素对肉兔消化代谢的影响.采用单因子随机区组试验设计,选择90只50日龄体重相近的健康新西兰兔,随机分为3组,1个对照组和2个试验组,每组15个重复,每个重复2只.对照组饲喂粗蛋白质含量为11.11％的基础饲粮,2个试验组分别饲喂在基础饲粮中以糊化淀粉缓释尿素的方式添加1％、2％和3％尿素的试验饲粮.预试期为10 d,正试期为30 d.正试期的第13～18天收集试验兔排出的全部粪便和尿液.结果表明:与对照组相比,1％尿素组试验兔的有机物表观消化率、总能表观消化率及利用率、沉积氮、氮利用率和消化氮利用率显著或极显著升高(P＜0.05或P＜0.01),而2％尿素组试验兔的消化能、代谢能、沉积氮、氮利用率和消化氮利用率显著或极显著降低(P＜0.05或P＜0.01).对照组试验兔盲肠内容物脲酶活性和微生物蛋白浓度显著或极显著低于其余2组(P＜0.05或P＜0.01),而2％尿素组试验兔盲肠内容物氨氮和尿素氮浓度显著或极显著高于其余2组(P＜0.05或P＜0.01).由此得出,低蛋白质饲粮中添加1％尿素可改善肉兔有机物、总能和氮的利用效率,提高盲肠内容物脲酶活性和微生物蛋白浓度;添加2％尿素则会降低肉兔氮的利用效率,提高盲肠内容物脲酶活性及微生物蛋白、氨氮和尿素氮浓度.     

饲粮中添加芦丁对湖羊生长性能、血清生化指标和激素水平及瘤胃发酵的影响

为研究饲粮中添加芦丁对湖羊生长性能、血清生化指标和激素水平及瘤胃发酵的影响,将36只健康且体重相近的湖羊随机分为3组,每组12只(公母各占1/2)。在3组湖羊所喂基础饲粮中分别添加0(试验Ⅰ组,作为对照组)、50(试验Ⅱ组)和100 mg/kg BW(试验Ⅲ组)的芦丁。试验期为70 d,其中预试期14 d,正试期56 d。结果显示:1)正试期第1～14天,试验Ⅰ组湖羊平均日增重显著低于其他2组(P0.05),而料重比则相反。2)正试期第14天,试验Ⅰ组湖羊血清葡萄糖含量显著高于试验Ⅱ组(P0.05),试验Ⅲ组湖羊血清高密度脂蛋白含量显著高于试验Ⅱ组(P0.05)。正试期第35天,试验Ⅲ组湖羊血清总蛋白含量显著低于其他2组(P0.05),而血清甘油三酯含量则相反。正试期第56天,试验Ⅲ组湖羊血清甘油三酯含量极显著高于其他2组(P0.01)。3)正试期第14天,试验Ⅱ组湖羊血清甲状腺素、三碘甲状腺原氨酸、瘦素、胰岛素以及皮质醇水平显著高于试验Ⅰ组(P0.05)。正试期第35天,试验Ⅲ组湖羊血清三碘甲状腺原氨酸、瘦素、胰岛素和生长激素水平显著高于试验Ⅰ组(P0.05)。正试期第56天,试验Ⅱ组湖羊血清雌二醇水平显著高于其他2组(P0.05);试验Ⅲ组湖羊血清甲状腺素、三碘甲状腺原氨酸以及生长激素水平显著高于试验Ⅰ组(P0.05)。4)试验Ⅱ组湖羊瘤胃液乙酸、丙酸、异戊酸、戊酸和总挥发性脂肪酸浓度显著高于试验Ⅲ组(P0.05)。试验Ⅰ组瘤胃液乙栖瘤胃普雷沃菌、溶纤维丁酸弧菌和嗜淀粉瘤胃杆菌基因相对表达量显著或极显著高于其他2组(P0.05或P0.01);试验Ⅱ组瘤胃液白色瘤胃球菌基因相对表达量显著或极显著高于其他2组(P0.05或P0.01)。综上所述,芦丁能够调控激素分泌和瘤胃发酵,进而改善湖羊的生长性能。在本试验条件下,湖羊饲粮中添加50 mg/kg BW芦丁时效果较好。     

玉米赤霉烯酮对小鼠血清生化指标及肝脏、肾脏组织结构的影响

将80只4周龄体质量18～22 g昆明雌性小鼠随机分为4组。对照组饲喂基础日粮,试验1、2、3组在基础日粮中分别添加50,100,150 mg/kg ZEA,预试期7 d,试验期20 d。结果显示,饲粮中添加100～150 mg/kg ZEA后,发情前期和发情期血清中BUN和LDL含量极显著升高(P0.01),TP、HDL、TC、TG的含量变化没有明显的规律;发情前期和发情期血清中MDA含量极显著升高(P0.01), T-AOC、T-SOD、GSH-Px活性极显著降低(P0.01);肾小球和肾小管萎缩。结果表明,饲粮中添加100～150 mg/kg ZEA后,极显著的降低了小鼠抗氧化能力,肾实质损伤显著。     

棉桃壳和氨化棉桃壳对绵羊的营养价值评定

选用4只体重28 kg左右,安装永久瘤胃瘘管甘肃高山细毛羯羊,采用4×4拉丁方试验设计,通过体内消化代谢试验对棉桃壳和氨化棉桃壳进行营养价值评定。结果表明,绵羊对棉桃壳和氨化棉桃壳消化能、干物质消化率、氮消化率、有机物质消化率、中性洗涤纤维消化率、酸性洗涤纤维消化率、钙消化率、磷消化率和氮存留率分别为11.42 和10.90 MJ/kg,68.41%和66.30%,60.30%和60.68%,70.25%和67.57%,57.44%和54.55%,54.78%和52.21%,27.66%和24.88%,34.56%和27.57%及49.48%和50.34%。氨化棉桃壳和棉桃壳的消化率无显著性差异(P>0.05);饲粮中添加棉桃壳和氨化棉桃壳对绵羊瘤胃液中乙酸、丙酸、丁酸和其他酸摩尔比及乙/丙和氨态氮与蛋白氮浓度均产生了显著的影响(P<0.05),对瘤胃液pH及TVFA、总氮和尿素氮浓度无显著影响(P>0.05)。试验表明棉桃壳和氨化棉桃壳养分表观消化率无显著差异,利用尿素进行氨化处理时绵羊瘤胃内释放氨的速度较快,瘤胃微生物合成强度较低。     

Haematology, blood biochemistry and tissue histopathology of lambs maintained on diets containing an insect controlling protein (Cry1Ac) in Bt-cottonseed

This experiment assessed the effect of feeding genetically modified cottonseed (Bt) containing an insect controlling protein (Cry1Ac) on haematology, blood biochemistry and histopathology of lambs. Haemato-biochemicals were estimated at periodic intervals, and histopathology at termination of experiment. Thirty three weaner lambs were fed a composite feed mixture (CFM) ad libitum individually, in three groups for 123 days. The isonitrogenous CFM had roughage (Perl Millet Stover) and concentrate ratio of 350:650. Diet fed to control lambs contained groundnut oil meal as protein source while other two groups received diet containing either whole cottonseed (N-Bt) or Bt-cottonseed (Bt-CS). Daily feed intake and average daily gain were similar among lambs of three groups. Lambs fed N-Bt diet had higher (p < 0.05) serum protein and globulin compared to control and Bt diets, while albumin content was higher (p = 0.018) in Bt diet fed lambs. Serum urea and creatinin content, alkaline phosphatase (ALP) and serum glutamate pyruvic transaminase (SGPT) activities were not different among lamb groups, while urea and creatinin content and ALP activities increased linearly (p < 0.001) with increased feeding period. Blood haemoglobin (Hb), haematocrit (Hc), white blood cells (WBC), mean corpuscular volume (MCV) and mean corpuscular haemoglobin concentration (MCHC) ranged from 11.1% to 11.2%, 31.8% to 32.8%, 7.0 to 8.3 (× 10(3) /μl), 19.1 to 22.5 fl and 33.2% to 35.5%, respectively, were similar among lamb groups. Erythrocyte sedimentation rate (ESR) (p = 0.008) and red blood cell counts (p = 0.006) were higher in Bt diet fed lambs. Control and N-Bt diet fed lambs had mild fatty infiltration in liver and/or micro-calculi in renal cortex, and such lesions were not seen in Bt diet fed lambs. Growth, haemato-biochemical and histopathology did not change by Bt-CS feeding in growing lamb. However, before recommending the use of Bt-CS in routine feed formulations prolonged feeding experiments of Bt-cotton seed require.     

几种棉粕饲料的质量评定

试验旨在研究棉粕感官鉴定结果同其营养成分化学检验结果的相关性,为生产中感官检测提供理论依据。采集市面上不同产地及不同厂家的6种棉粕,测定其所含粗蛋白、游离棉酚、NDF、ADF、ADL的量。结果表明,6种棉粕所含游离棉酚量都在国标允许范围内,并且棉粕的色泽与游离棉酚含量有一定的相关性。试验数据表明,黄色棉粕较发红的棉粕游离棉酚含量高。棉壳含量是影响棉粕粗蛋白高低的主要因素,两者呈明显的负相关。棉壳和棉絮含量与纤维呈正相关,棉壳和棉絮含量过高则会影响到棉粕的品质。     

Effects of supplement feeding order on lactation, diurnal variation of ruminal ammonia and urea in the blood and milk of dairy cows

The present study examined the effects of feeding order of grain and protein supplements on ruminal nitrogen (N) loss through the diurnal variation of ruminal ammonia N and urea N in the blood and milk of dairy cows. Three ruminally fistulated cows were used in a 3 × 3 Latin square arrangement of treatments; that is, grain supplement fed at the first feed and then the protein supplement at the second (GS‐1st), protein supplement fed first and then the grain supplement (PS‐1st), and the grain and protein supplements mixed and divided into equal portions fed at each supplement feeding time (GP‐mix). No differences in the lactation parameters were observed among the treatments. In GS‐1st treatment, the increase in the concentration of ruminal ammonia N was inhibited after feeding, and the concentration was lower (P < 0.05) than with the other treatments 1–2 h after basal feeding. The concentrations of urea N in the blood and milk with the GS‐1st treatment were the lowest of all treatments throughout the sampling times, and were lower (P < 0.05) than with the GP‐mix treatment except for blood levels 1 h after basal feeding. The results suggest that grain feeding before protein feeding can reduce ruminal N loss.     

Intake and ingestive behavior of lambs fed diets containing ammoniated buffel grass hay

This study aimed to evaluate the effect of diets with ammoniated buffel grass hay on the ingestive behavior of feedlot lambs. Thirty-two sheep of no defined breed with an average body weight of 17.7?±?1.8 kg were used. A completely randomized design with four treatments (0, 18, 36, and 54 g/kg dry matter (DM) basis) and eight repetitions was used. Ingestive behavior, rumination, and idle time were similar (P?>?0.05) among the diets containing ammoniated buffel grass hay, with mean values of 294.5, 554.44, and 594.25 min per day, respectively. Regarding the chews, all of the variables resulted in similar behavior (P?>?0.05). The quadratic effect (P?<?0.05) observed for daily intake can be explained based on the amount of DM and neutral detergent fiber (NDF) per meal per rumination. There was no effect of urea levels from the ammoniation (P?>?0.05) on the efficiency of DM and NDF consumption. However, the rumination efficiency of DM and NDF showed a quadratic effect (P?<?0.05). Thus, the use of ammoniated buffel grass hay with urea in lamb diet affects the ingestive behavior by increasing the rumination efficiency, increased intake, and feed utilization.     

Source and level of energy supplementation for yearling cattle fed ammoniated hay

Brahman x British crossbred steers were used in growth and digestion trials to evaluate the response of source (corn, sugar cane molasses, or soybean hulls) and feeding rate (0, 1.4, or 2.8 kg DM per steer daily in the growth trials; 0, 15, or 30% of the ration DM in the digestion trial) of energy supplementation in cattle fed ammoniated (4% of forage DM) stargrass (Cynodon nlemfuensis Vanderyst var. nlemfuensis) hay. Cattle on all treatments were fed 0.5 kg cottonseed meal daily. In the growth trials, steers grazed dormant bahiagrass (Paspalum notatum) pasture. Increasing the levels of supplementation decreased hay intake but increased total dietary intake for all diets (P < 0.07). Daily gain and feed efficiency of steers were improved (P < 0.03) with supplementation. Steers supplemented with corn or soybean hulls at 2.8 kg DM/d had a higher ADG (0.92 kg) and gain/feed (0.103) than steers supplemented with molasses (0.78 kg, 0.08, respectively) at the same level. Seven crossbred steers (200 kg) were used in a five-period digestion trial to evaluate apparent OM, NDF, ADF, and hemicellulose digestibility. Apparent OM digestibility of all diets increased linearly (P = 0.02) as the level of supplementation increased. Apparent NDF and ADF digestibility decreased (P < 0.03) as the level of supplementation with corn or molasses increased, whereas increasing the level of soybean hulls in the diet increased (P < 0.06) apparent NDF and ADF digestibility. Four ruminally fistulated crossbred steers (472 kg) were used in a 4 x 4 latin square design to investigate ruminal characteristics with energy supplementation at 30% of ration DM. Ruminal pH in steers supplemented with soybean hulls or corn declined after feeding. Ruminal pH decreased more rapidly with corn supplementation and remained below 6.2 for a longer period of time than with the other diets. Ruminal pH did not change within 24 h after feeding for steers fed the control or molasses diets. No change in total VFA concentration was observed in steers fed molasses or corn. Total ruminal VFA concentration in steers supplemented with soybean hulls increased initially after feeding and then declined within 24 h after feeding. Soybean hulls produced fewer negative associative effects than corn when fed with ammoniated stargrass hay at 2.8 kg DM/d. The reduced gain/feed of steers supplemented with molasses compared to soybean hulls or corn indicates that molasses was not utilized as efficiently as the other energy sources.     

Comparison of silage and hay of dwarf Napier grass (<Emphasis Type="Italic">Pennisetum purpureum</Emphasis>) fed to Thai native beef bulls

Both quantity and quality of forages are important in dry season feeding. Eight Thai native beef bulls were arranged in a Completely randomized design to evaluate dwarf Napier namely Sweet grass (Pennisetum purpureum cv. Mahasarakham) preserved as silage or hay on feed intake, digestibility, and rumen fermentation. The animals were fed with forage ad libitum supplemented with concentrate mixture at 1.0% of BW for 21 days; data were collected during the last 7 days. The results showed that there were differences (P?<?0.05) between treatments in dry matter (DM) intake, DM digestibility, and ruminal pH, in which hay feeding gave enhanced feed intake and more favorable ruminal pH. Nevertheless, mean ruminal ammonia nitrogen, total volatile fatty acids (TVFAs), proportion of VFAs, bacterial and protozoal population, and blood urea nitrogen were similar (P?>?0.05) in animals fed silage and hay. Sweet grass is better preserved as hay rather than silage.     

Effects of laidlomycin propionate and monensin on the in vitro mixed ruminal microorganism fermentation.

The objective of this study was to compare the effects of laidlomycin propionate and monensin on the in vitro fermentation of ground corn, Trypticase, or alfalfa hay by mixed ruminal microorganisms. Ruminal fluid was collected from two steers fed 9.27 kg DM of a high-concentrate (62.2% ground corn and 17.4% cottonseed hulls) diet per day and composited. In the first study, no ionophore was included in the diet; the diet in the second study contained 11.1 g of laidlomycin propionate per ton of feed. The animals were allowed an adjustment period of 14 d for each dietary treatment before samples were collected. When ruminal fluid from unadapted animals was used, both monensin and laidlomycin propionate decreased (P<.05) CH4 concentration and the acetate:propionate ratio with ground corn and alfalfa hay. Monensin reduced (P<.05) in vitro dry matter disappearance of alfalfa and increased (P<.05) final pH in the ground corn and alfalfa hay fermentations. Both laidlomycin propionate and monensin decreased (P<.05) concentrations of acetate, propionate, isobutyrate, isovalerate, CH4, and NH3 in Trypticase fermentations. When ruminal fluid from adapted animals was used, both ionophores still reduced the concentrations of most fermentation products. However, there was generally less inhibition compared with fermentations inoculated with unadapted mixed ruminal microorganisms. In the presence of 5 mM maltose, mixed ruminal bacteria produced high concentrations (10 to 11 mM) of lactate, and addition of both ionophores to these fermentations was effective in reducing (P<.05) lactate production. In conclusion, laidlomycin propionate alters the mixed ruminal microorganism fermentation in a manner similar to monensin, but, at the concentrations used in this study, monensin seemed to be a more potent inhibitor.     

Influence of dietary urea level on digestive function and growth performance of cattle fed steam-flaked barley-based finishing diets

Four Holstein steers (282 kg) with cannulas in the rumen and proximal duodenum were used in a 4 x 4 Latin square experiment to evaluate the influence of dietary urea level (0, 0.4, 0.8, and 1.2%, DM basis) in a steam-flaked barley-based finishing diet on digestive function. There were no treatment effects (P > 0.20) on ruminal digestion of OM and ADF. Increasing dietary urea level increased (linear, P < 0.01) ruminal starch digestion. Ruminal degradability of protein in the basal diet (no supplemental urea) was 60%. Increasing dietary urea level did not increase (P > 0.20) ruminal microbial protein synthesis or nonammonia N flow to the small intestine. There were no treatment effects (P > 0.20) on total-tract ADF digestion. Total tract digestion of OM (quadratic, P < 0.01) and starch (linear, P < 0.05) increased slightly with increasing urea level. Urea supplementation increased (linear, P < 0.01) ruminal pH 1 h after feeding; however, by 3 h after feeding, ruminal pH was lower (cubic, P < 0.05) with urea-supplemented diets. Urea supplementation did not affect (P > 0.20) ruminal molar proportions of acetate and propionate. One hundred twenty crossbred steers (252 kg; approximately 25% Brahman breeding) were used in an 84-d feeding trial (five pens per treatment) to evaluate treatment effects on growth performance. Daily weight gain increased (linear, P = 0.01) with increasing urea level, tending to be maximal (1.53 kg/d; quadratic, P = 0.13) at the 0.8% level of urea supplementation. Improvements in ADG were due to treatment effects (linear, P < 0.01) on DMI. Urea supplementation did not affect (P > 0.20) the NE value of the diet for maintenance and gain. Observed dietary NE values, based on growth performance, were in close agreement with expected based on tabular values for individual feed ingredients, averaging 100.4%. We conclude that with steam-flaked barely-based finishing diets, ruminal and total-tract digestion of OM and ruminal microbial protein synthesis may not be increased by urea supplementation. In contrast, ADG was optimized by dietary inclusion of 0.8% urea. Urea supplementation may not enhance the net energy value of steam-flaked barely-based finishing diets when degradable intake protein is greater than 85% of microbial protein synthesis.     

6种饲料原料瘤胃降解特性和瘤胃非降解蛋白质的小肠消化率

本试验旨在研究新疆地区玉米青贮、棉籽壳、苜蓿草粉、苜蓿干草、葡萄籽粕、蕃茄酱渣6种奶牛饲料原料的瘤胃降解特性和瘤胃非降解蛋白质(RUP)的小肠消化率(Idg)。选用3头装有永久性瘤胃瘘管的泌乳荷斯坦奶牛,采用尼龙袋法和改进三步体外法测定饲料原料的干物质(DM)、粗蛋白质(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解特性以及RUP的Idg和小肠可消化粗蛋白质(IDCP)含量。结果表明:1)苜蓿草粉和玉米青贮的DM有效降解率最高,显著高于次之的苜蓿干草、番茄酱渣(P0.05),葡萄籽粕、棉籽壳最低,显著低于其他原料(P0.05);CP有效降解率为番茄酱渣苜蓿草粉玉米青贮苜蓿干草棉籽壳葡萄籽粕,各原料间差异显著(P0.05);NDF有效降解率为玉米青贮苜蓿草粉棉籽壳苜蓿干草番茄酱渣葡萄籽粕,各组饲料原料间差异显著(P0.05);ADF有效降解率为玉米青贮棉籽壳苜蓿干草番茄酱渣苜蓿草粉葡萄籽粕,各组饲料原料间差异显著(P0.05)。2)苜蓿草粉RUP的Idg和IDCP含量最高,Idg显著高于依次降低的苜蓿干草、玉米青贮、番茄酱渣、葡萄籽粕、棉籽壳(P0.05),IDCP含量与苜蓿干草差异不显著(P0.05),显著高于依次降低的玉米青贮、番茄酱渣、葡萄籽粕、棉籽壳(P0.05)。综上所述,不同饲料原料具有不同的瘤胃降解特性,进入小肠IDCP的含量也不同。玉米青贮的DM、NDF和ADF在瘤胃的有效降解率较高,苜蓿草粉RUP的Idg较高,苜蓿草粉和苜蓿干草的IDCP含量较高。