不同精料水平对肉牛饲料利用效率的影响

试验采用尼龙袋法研究肉牛不同精料水平日粮的营养物质转化效率，以求提高肉牛对粗饲料的利用效率，并为选择肉牛日粮适宜的精粗比提供理论依据。     

论反刍动物饲料蛋白质的保护方法

对于维持饲养和低生产水平的奶牛,靠微生物蛋白和饲料未降解蛋白,甚至仅靠微生物蛋白就可满足需要,但对于快速生长犊牛和高产奶牛（尤其是泌乳初期）,微生物蛋白和饲料未降解蛋白就不能满足需要了。由于在能量一定、氮源充足的情况下,微生物产量相对稳定,所以解决此...     

饲料蛋白质的消化、吸收和利用及其影响因素分析

饲料蛋白质首先要在鱼体消化道内被消化酶分解为可以被鱼体吸收的小分子物质如氨基酸、小肽后才能进入鱼体内，这些成分进入体内后将被氧化产生能量，转化为其它物质如脂质碳水化合物，用于体内蛋白质的合成。正确认识饲料蛋白质被水解、吸收和利用的过程除对鱼类营养基础研究有重要价值外，对提高饲料蛋白质的消化利用率、发展无鱼粉配合饲料具有决定性的作用。     

离子载体对杂种肉牛营养物质消化与氮平衡的影响

为了研究莫能霉素、盐霉素和拉沙里菌素3种离子载体对杂种肉牛营养物质消化和氮代谢的影响,以4头30～35月龄、体重380～450kg的西门塔尔×中国黄牛杂交一代公牛为试验动物,采用4×4拉丁方设计,进行消化试验和氮平衡试验。结果表明:莫能霉素、盐霉素和拉沙里菌素显著提高日粮粗纤维的消化率12.96%、16.24%和6.95%(P<0.05)和进食氮的沉积率24.67%、6.38%和23.22%(P<0.05);但对日粮干物质和粗蛋白的消化率、可消化氮的沉积率没有显著影响(P>0.05)。     

氯化锌对饲料蛋白质瘤胃降解的影响

探索用新的蛋白质保护剂氯化锌保护豆粕、棉籽粕、菜籽粕和胡麻粕4种饲料,用尼龙袋法测定4种饲料处理前后蛋白质的瘤胃降解率。结果表明:ZnCl2处理可以降低饲料蛋白质在瘤胃的降解率,能够保护饲料蛋白质,提高过瘤胃蛋白的数量。0.5%ZnCl2处理可降低豆粕、棉籽粕、菜籽粕和胡麻粕蛋白质有效降解率8.2%、3.8%、14.9%和9.8%。从降解动力学分析,ZnCl2处理降低了饲料蛋白质的快速降解部分和降解速度,从而降低了蛋白质的有效降解率。     

肉牛常用饲料和饲料添加剂

肉牛饲料由粗饲料、青绿饲料、青贮饲料、能量饲料、蛋白质饲料、矿物质饲料、维生素和添加剂等部分组成.     

调控进入小肠蛋白质和淀粉水平对肉牛氮代谢及血液生化指标的影响

用4头装有瘤胃和真胃瘘管的成年肉牛 ,采用4×4完全拉丁方试验设计 ,研究了4种处理 :A(1.2M羊草基础日粮 +食入普通豆粕710g+食入淀粉320g)、B(1.2M羊草基础日粮 +食入保护豆粕710g+食入淀粉320g)、C(1.2M羊草基础日粮 +食入普通豆粕710g +真胃灌注淀粉320g)和D(1.2M羊草基础日粮 +食入保护豆粕710g+真胃灌注淀粉320g) ,对可消化氮转化为沉积氮的效率(RN/DN)、氮沉积量(RN)和血液生化指标的影响。结果表明 :(1)RN(g/d)、RN/DN( %)、血糖(G)、胰岛素(INS)和生长激素(GH)浓度随着进入真胃(小肠)非降解养分(蛋白质、淀粉)量的增加而提高。D处理(非降解蛋白200g +真胃灌注淀粉320g)的RN(g/d)比A、B、C处理分别提高63.24%(P<0.01)、56.32 %(P<0.01)和22.62 %(P<0.05)。(2)血清中GH、INS和G含量与RN(g/d)和RN/DN( %)存在线性正相关关系。     

蛋白质数量和降解性对奶牛氮利用率的影响

泌乳早期，奶牛需要大量的粗蛋白(CP)，含氮(N)化合物流入小肠的数量受瘤胃中日粮蛋白质降解和微生物蛋白质合成程度的影响。瘤胃合成的微生物蛋白质数量不足以满足高产牛的氨基酸需要量。因此，提高牛奶生产所需氨基酸供给的常见措施是饲喂瘤胃降解性低的补充蛋白质。本试验目的是，确定日粮中蛋白质数量和降解性对泌乳奶牛养分消化、微生物蛋白质合成和养分流入小肠的影响。     

包被硝酸钙替代豆粕对公羊能量分配和氮利用的影响

文章旨在评估包被硝酸钙替代豆粕对山羊能量分配、底物氧化和微生物氮合成方面的影响。试验采用在3×3拉丁方设计,选用24只初始体重为(21.9±3.19)kg的阉割公山羊开展3个为期48d的试验,试验动物随机分为3组,3种日粮分别是豆粕组(对照组),15%包被硝酸钙组和30%包被硝酸钙组,每个阶段包括21d的适应期,5d的代谢试验,15d的间接测热试验。结果结果显示,随着日粮包被硝酸钙添加水平的升高,血液高铁血红蛋白浓度表现为显著线性升高(P<0.05)。日粮添加15%包被硝酸钙组有机物、中性洗涤纤维、酸性洗涤纤维和总能摄入量最高(P<0.05)。氮摄入量和沉积量随包被硝酸钙添加水平的升高显著线性降低(P<0.05),肠道甲烷产量表现为显著线性降低(P<0.05)。总能、消化能、代谢能摄入量随包被硝酸钙水平的升高表现为显著二次曲线效应(P<0.05)。随着日粮包被硝酸钙水平的升高,非蛋白呼吸熵显著线性降低(P<0.05)。结论:包被硝酸钙降低了山羊禁食产热,替代豆粕后对肠道微生物蛋白的合成无显著影响。在本试验条件下,日粮添加15%包被硝酸钙可以使山羊干物质、消化能和代谢能的摄入量达到最大化。     

Effects of crude protein concentration and degradability on performance, carcass characteristics, and serum urea nitrogen concentrations in finishing beef steers

Two experiments were conducted at two locations to determine the effects of dietary CP concentration and source on performance, carcass characteristics, and serum urea nitrogen (SUN) concentrations of finishing beef steers. British x Continental steers were blocked by BW (357 +/- 28 and 305 +/- 25 kg initial BW; n = 360 and 225; four and five pens per treatment in Exp. 1 and 2, respectively). Steam-flaked corn-based diets were arranged in a 3 x 3 factorial with three CP concentrations (11.5, 13, or 14.5% of DM) and three sources of supplemental CP (N basis): 100% urea; 50:50 blend of urea and cottonseed meal; or 100% cottonseed meal. Steers in both experiments were initially implanted with Ralgro and reimplanted with Revalor-S on d 56. Performance and carcass data were pooled across locations. Crude protein concentration x source interactions were not observed (P = 0.22 to 0.93) for performance and carcass data. Crude protein concentration affected ADG (P = 0.02) and carcass-adjusted (to a common dressing percent within location) ADG quadratically (P = 0.06). Increasing the concentration of supplemental urea linearly increased carcass-adjusted ADG and G:F (P < 0.05) and carcass-adjusted G:F (P < 0.001). Dry matter intake was not affected (P = 0.93) by either CP concentration or source. Hot carcass weight (HCW; P = 0.02), LM area (P = 0.05), and dressing percent (P = 0.03) increased linearly with increasing urea concentration, whereas increasing CP concentration quadratically affected HCW (P = 0.02), with a maximum at 13% CP. Differences in backfat thickness and yield grade were negligible across treatments. Neither marbling score nor percentage of carcasses grading USDA Choice was affected by CP concentration or source. At all times measured, SUN concentrations increased (P < 0.05) with increasing CP concentration, but effects of CP source were small and variable across time. Results indicate that increasing CP concentrations from 11.5 to 13% slightly increased ADG and carcass-adjusted ADG, whereas increasing the proportion of supplemental urea increased carcass-adjusted ADG, G:F, and carcass-adjusted G:F and increased HCW, LM area, and dressing percent. A CP concentration above 13% seemed detrimental to ADG and HCW. Serum urea N increased over time, with CP concentration having a greater effect than CP source.     

单宁酸对绵羊日粮养分消化利用及氮代谢的影响

通过在饲料中添加不同比例的分析纯单宁酸(鞣酸),对绵羊营养物质消化利用及氮代谢参数的影响进行了研究,并探讨分析纯单宁酸在饲粮中的适宜添加量。试验选用4只安装永久性瘤胃瘘管的羯绵羊(2岁,平均体重为35±2.15 kg)作试畜,采用4×4拉丁方设计进行试验,研究了饲粮单宁酸水平(A、B、C、D分别为0、10、15、20 g/kg DM)对绵羊养分消化利用与氮代谢参数的影响,16 d(预试期10 d,正试期6 d)为一个饲粮循环,全期共64 d。结果表明,高浓度单宁酸(20 g/kg DM)影响绵羊的采食量,进而影响绵羊对干物质(DM)、有机物(OM)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)的食入量(P<0.01);但随着单宁酸浓度的增加,绵羊对DM、OM、NDF、ADF、Ca、P的消化率并无显著影响(P>0.05);处理组A、B、C的N食入量与N消化量极显著高于D(P<0.01),N存留率随单宁酸比例的增大而升高,仅C处理组显著高于A(P<0.01);N消化率、pH、总N浓度差异不显著(P>0.05);而瘤胃液NH₃-N浓度和尿素氮(BUN)呈线性下降,A的NH₃-N显著高于D(P<0.05),而其血浆尿素氮(BUN)高于C、D(P<0.01)。可见,单宁酸具有提高蛋白质在绵羊体内消化吸收的功效;饲粮中单宁酸含量小于15 g/kg DM时,能够显著提高氮存留率,对蛋白质保护的效果较好;故单宁酸在饲粮中的添加量不应该超过15 g/kg DM。     

Effects of forage particle size, level of feed intake and supplemental protein degradability on microbial protein synthesis and site of nutrient digestion in steers

A 2(3) factorial arrangement of treatments was used to study main effects and interactions between particle size of prairie hay (chopped vs ground), two levels of feed intake (60 and 90% of ad libitum) and ruminal degradability of protein sources [dry corn gluten feed (DCGF) vs dry distillers grains (DDG)] on ruminal and total tract digestion in eight ruminal- and duodenal-cannulated steers. Steers were fed every 2 h to approach steady-state feeding conditions. Steers fed ground hay diets digested higher (P less than .05) percentages of total digestible organic matter (OM) and neutral detergent fiber (NDF) in the rumen and had lower (P less than .05) nonammonia-nonbacterial N (NANBN) flows to the duodenum than did those fed chopped hay, probably because greater surface area of ground hay allowed more extensive ruminal fermentation. Protein source X intake interactions were noted for ruminal OM and NDF digestion when expressed as percentages of total digestion. At low intakes, steers fed DCGF had higher (P less than .05) percentages of total digestible OM and NDF disappearing in the rumen than did those fed DDG. Steers fed DCGF had lower total N, NANBN and total amino acid (AA) flows at the duodenum than did those fed DDG, indicating that less DCGF protein escaped ruminal degradation. Steers fed DDG had greater (P less than .05) total tract NDF digestion, suggesting that escape protein from DDG may stimulate hindgut fermentation and thereby affect site and extent of nutrient digestion. Regression analysis indicated that extent of ruminal fermentation and efficiency of microbial growth in vivo are associated with ruminal rates of passage within individual animals. When steers were fed at high-intake levels (1.6% of body weight), ruminal dilution rates were not increased (P less than .05) due to forage particle size or level of intake treatments, accounting, in part, for the lack of expected treatment differences in efficiency of bacterial growth and duodenal N flow, and for the low number of interactions between main effects.     

我国大陆唯一的大面积成群落分布的优良水土保持植物--香根草的用途与保护问题

香根草根系深2－3m，已被世界上许多国家列为理想的水土保持植物种，也是受重金属和有机物污染土地复垦的首选物种之一，其香根油还有重要的经济价值。我国大面积存在的天然香根草群落位于广东省湛江地区，现存面积50hm^2左右，建议应尽快把这块仅有的野生香根草草地划为自然保护区，为国内外研究者提供一个天然香根草的研究基础。     

秦川牛遗传资源保护和开发利用工作的思考

农业农村部《“十四五”全国畜牧兽医行业发展规划》指出,要加强畜禽种质资源保护和利用、强化畜禽种质创新、加快良种繁育与推广、加强种畜禽重点疫病净化。实施第三次全国畜禽遗传资源普查,加快抢救性收集保护,确保重要资源不丢失、种质特性不改变、经济性能不降低。结合各地资源条件和养殖基础,明确优势区域主推品种,健全畜禽良种推广体系。本文联系实际,从秦川牛遗传资源保护工作的基本情况入手,分析了当前秦川牛遗传资源保护工作中存在的5个方面的具体困难和实际问题,并针对性地提出了做好秦川牛遗传资源保护与开发利用7条操作性强的路径和举措,对进一步做好我国地方特色畜牧优良品种秦川牛遗传资源保护和开发,促进秦川牛种业更好发展具有理论指导和现实意义。     

Effects of pre-feeding of a corn silage-based supplement on the feed intake, milk production and nitrogen utilization of grazing dairy cows

Four Holstein cows were used to determine the effect of timing of the feeding of a corn silage (CS)‐based supplement on the feed intake, milk production and nitrogen utilization of grazing dairy cows. The cows were fed the supplement 2 h before grazing (pre‐grazing) or immediately after grazing (post‐grazing). Cows were grazed for 5 h per day under a rotational grazing system. There was no difference in the herbage and total feed intake between treatments. The milk protein yield for pre‐grazing tended to be higher than that for post‐grazing, whereas the milk yield did not differ between treatments. The total nitrogen intake for pre‐grazing tended to be higher than that for post‐grazing (P = 0.06). There was no difference in the urinary nitrogen output between treatments, whereas the proportion of urinary nitrogen output : total nitrogen intake for pre‐grazing tended to be lower than that for post‐grazing (P = 0.06). The milk nitrogen output and nitrogen retention for pre‐grazing tended to be higher than that for post‐grazing (milk nitrogen, P = 0.06; nitrogen retention, P = 0.05). Nitrogen utilization of grazing dairy cows was improved by feeding a CS‐based supplement before grazing.     

内蒙古梭梭荒漠草地资源及其保护利用

在简述梭梭荒漠地理分布的基础上,着重阐述了内蒙古梭梭荒漠植物区系特征,植物学特征,生态环境和生物学特性,经济价值,内蒙古梭梭荒漠草地资源在全国和内蒙古天然草地及荒漠草地中的地位、现状、重点保护及合理利用.     

山楂对鲫鱼的生长及饵料利用率的影响

试验旨在研究5种等氮、等能饲料中添加不同水平山楂对鲫鱼生长、饲料利用的影响。试验选用平均初始体重为(8.34±0.21)g的鲫鱼,随机选取分为5个处理组,每组30尾,每组设3个重复。试验采用单因素设计,用添加不同水平山楂(添加量分别为0、1%、3%、5%、7%)的饲料喂养鲫鱼,试验期60d。结果表明:饲料中山楂添加量为3%时,试验鱼的特定生长率最大(1.83%/d)、蛋白效率最高(1.92%)、饵料系数最低(1.76)。与其余各试验组相比差异显著(P<0.05)。用折线回归模型分析山楂的添加量与鲫鱼特定生长率、饵料蛋白效率及饵料系数的变化关系,表明本试验中鲫鱼饲料中山楂的适宜添加量为3%。