年龄及泌乳阶段对荷斯坦奶牛日粮钙、磷表观消化率的影响

本文对不同阶段荷斯坦育成牛(12月龄、18月龄、24月龄)、泌乳牛(1、2、5、9泌乳月)及围产期牛(围产前期、围产后期)的日粮Ca、P表观消化率进行了比较研究。试验奶牛饲喂生产日粮,各阶段育成牛日粮Ca含量为8.8~9.4g/kg,P含量为3.1~3.2g/kg;各阶段泌乳牛日粮Ca含量为10.2~10.6g/kg,P含量为5.6g/kg;围产期牛各阶段Ca含量为10.6~14.0g/kg,P含量为3.8~5.6g/kg。研究结果表明,24月龄和12月龄育成牛日粮Ca、P表观消化率差异不显著(P0.05),Ca表观消化率均显著高于18月龄(P0.05),P表观消化率极显著高于18月龄(P0.01)。泌乳牛日粮Ca、P表观消化率随泌乳期的延长而降低,1泌乳月、2泌乳月奶牛日粮Ca、P表观消化率显著高于5泌乳月、9泌乳月奶牛(P0.05),1泌乳月与2泌乳月及5泌乳月与9泌乳月之间的日粮Ca、P表观消化率差异均不显著(P0.05)。围产后期奶牛日粮Ca、P表观消化率显著高于围产前期奶牛日粮Ca、P表观消化率(P0.05)。研究结果显示,奶牛日粮Ca、P表观消化率受需要量和供给量的影响,适当控制日粮Ca、P含量可以提高其利用效率。     

不同泌乳阶段对荷斯坦牛干物质采食量和钙磷消化率的影响

试验研究了不同泌乳阶段荷斯坦牛干物质采食量和钙、磷表观消化率的变化趋势。结果表明:泌乳9月、5月奶牛干物质采食量显著高于泌乳1月奶牛(P<0.05);泌乳1月、2月奶牛产奶量显著高于泌乳5月、9月奶牛;泌乳期内不同泌乳阶段对奶牛Ca、P表观消化率影响显著(P<0.05),泌乳1月和2月奶牛Ca、P表观消化率显著高于泌乳5月和9月(P<0.05)。     

热应激对不同品种(系)青年肉牛生产性能、营养物质表观消化率及血液生化指标的影响

本试验旨在研究热应激对不同品种(系)青年肉牛生产性能、营养物质表观消化率及血液生化指标的影响,探究不同品种(系)肉牛的耐热性差异。选取体重[(185.89±14.02)kg]相近、健康的青年西杂牛(西门塔尔牛×宣汉黄牛)、地方黄牛(宣汉黄牛)和犏牛(娟姗牛×麦洼牦牛)各6头为研究对象,试验期间不同品种(系)的青年肉牛饲喂相同饲粮。试验时间为2015年4—9月,预试期7d,正试期180d。结果表明:1)试验牛舍5—8月温湿度指数(THI)高于72,属于热应激期,且显著高于4月(热应激发生前)和9月(热应激发生后)(P0.05);热应激环境导致各试验牛呼吸频率和直肠温度显著升高(P0.05)。试验期间犏牛呼吸频率和直肠温度显著高于西杂牛和地方黄牛(P0.05)。2)热应激期内西杂牛、地方黄牛和犏牛单位体重干物质采食量均有不同程度降低,以6月为最低,均较4月显著降低(P0.05),且降低幅度为犏牛西杂牛地方黄牛。西杂牛、地方黄牛和犏牛的平均日增重(ADG)均在6月最低,分别较4月降低了27.62%(P0.05)、10.81%(P0.05)和46.15%(P0.05);西杂牛的ADG在4—7月显著高于犏牛(P0.05)。西杂牛和犏牛的料重比(F/G)以6月为最高,分别较4月升高了63.01%(P0.05)和89.03%(P0.05);地方黄牛的F/G在9月最高,较4月升高了53.12%(P0.05)。3)热应激期内西杂牛、地方黄牛和犏牛的粗蛋白质(CP)表观消化率均有不同程度降低,且7月均较4月显著降低(P0.05);西杂牛7月的粗脂肪(EE)表观消化率较4月显著降低(P0.05),而热应激对地方黄牛和犏牛的EE表观消化率无显著影响(P0.05);热应激期内犏牛中性洗涤纤维(NDF)(6月)和酸性洗涤纤维(ADF)的表观消化率(5—8月)较热应激发生前显著降低(P0.05);热应激期内西杂牛和犏牛钙(Ca)(西杂牛:6—8月;犏牛:5—8月)和磷(P)的表观消化率(西杂牛:6—7月;犏牛:5—8月)较热应激发生前显著降低(P0.05)。试验期间,不同品种(系)牛的CP表观消化率无显著差异(P0.05),西杂牛和地方黄牛的EE表观消化率显著高于犏牛(P0.05),地方黄牛的ADF表观消化率显著高于西杂牛和犏牛(P0.05),西杂牛和地方黄牛的P表观消化率显著高于犏牛(P0.05)。此外,5—9月地方黄牛的Ca表观消化率显著高于犏牛(P0.05)。4)西杂牛、地方黄牛和犏牛血清中葡萄糖(GLU)浓度均以6月最低,较4月分别降低了16.82%(P0.05)、12.82%(P0.05)和15.90%(P0.05);热应激期间各试验牛血清中非酯化脂肪酸(NEFA)浓度均以7月最低,显著低于4月(P0.05);试验期间西杂牛和地方黄牛血清中尿素氮(UN)浓度随年龄的增大呈先升高后降低变化,而犏牛血清中UN浓度则持续升高;6—9月各试验牛血清肌酐(CRE)浓度均显著高于4、5月(P0.05),且7—9月犏牛血清CRE浓度显著高于地方黄牛(P0.05)。综上所述,热应激导致不同品种(系)青年肉牛生产性能降低、饲粮营养物质消化率降低,地方黄牛的耐热应激能力强于西杂牛和犏牛,犏牛对热应激最敏感。     

盐藻粉、壳聚糖和VA对奶牛日粮中氮、钙与磷表观消化率的影响

试验主要通过研究壳聚糖、盐藻粉、VA对奶牛日粮中N、Ca及P表观消化率的影响,旨在为科学地确定奶牛日粮中壳聚糖、盐藻粉及VA的添加剂量提供理论依据。试验分两部分进行,试验一选用18头荷斯坦奶牛作为试验动物,随机分成壳聚糖组、盐藻粉组和对照组,每组6头,壳聚糖和盐藻粉在奶牛日粮中的添加剂量为15g/(d·头)、9mg/(d·头),对照组不添加。试验二选用24头荷斯坦奶牛作为试验动物,采用2×2随机试验设计分成4个处理组,各组在基础日粮中添加不同水平(110、165IU/kg·BW)及处理(未处理、过瘤胃保护)的VA。2个试验的试验期均为60d,其中预饲期10d,正试期50d。试验结果表明,奶牛日粮中添加壳聚糖可以显著地提高日粮N、P的表观消化率,降低Ca的表观消化率(P<0.05)。盐藻粉可以显著地提高日粮中N的表观消化率(P<0.05)。奶牛日粮中添加高剂量(165IU/kg·BW)的VA及过瘤胃保护的VA对日粮N、P、Ca的表观消化率无显著的影响,但N、P表观消化率有增加的趋势,Ca的表观消化率有降低的趋势。     

复合酵母培养物对奶牛尿中嘌呤衍生物及养分消化率的影响

本试验旨在研究复合酵母培养物(CYC)对奶牛尿中嘌呤衍生物排出量及养分消化率的影响。选取年龄、体重、产奶量、乳成分及泌乳期相近(105.3±12.5)d的荷斯坦奶牛24头,分为4组,对照组和3个试验组每头每天分别添加0、80、100、120 g CYC,随全混合日粮(TMR)饲喂,预试期15 d,正试期30 d。结果表明:试验2组尿中嘌呤衍生物排出量极显著高于对照组(P0.01),试验1组、3组显著高于对照组(P0.05);在DM、Ca和P的表观消化率方面,试验2组显著高于对照组(P0.05),试验1组和3组与对照组差异不显著(P0.05),各试验组间差异不显著(P0.05);在CP表观消化率方面,试验2组、3组显著高于对照组(P0.05),试验1组与对照组无显著差异(P0.05),各试验组间差异不显著(P0.05);添加CYC对NDF和ADF的表观消化率无显著影响(P0.05)。由此可见,在本试验条件下,复合酵母培养物的适宜添加量为每头每天100 g。     

不同比例的羊草纤维素源对五龙鹅消化代谢的影响

选取18月龄的健康五龙鹅24只,随机分为4个组,每组6个重复.各试验组日粮添加的羊草粉含量分别为12.70%、16.70%、21.00%、25.80%,采用全收粪法进行消化代谢试验,检测饲料和粪便中的多种营养成分,确定其消化率.结果表明:在代谢能(ME)和粗蛋白(CP)等摄入量一致的条件下,随着羊草粉添加水平的提高,CF的消化率为13.00%～18.40%,中性洗涤纤维(NDF)14.10%～21.47%,酸性洗涤纤维(ADF)15.40%～22.29%;组间净蛋白利用率(NPU)及氮(N)的沉积量差异不显著(P>0.05),粪中氨态氮(N<,3>-N)浓度显著下降(P<0.05),各种氨基酸表观消化率(AAAD)较高(77.30%～91.78%);P的表观消化率各组间差异不显著(P>0.05),而Ca的表观消化率呈递减趋势(P<0.05);AKP活性与CF、NDF和ADF的消化率呈显著负相关(P<0.05),与Ca、蛋氨酸(Met)、胱氨酸(Cys)消化率呈显著正相关(P<0.05)ACP活性与Ca、P表现消化率呈显著正相关(P<0.05);其它四种酶的活性与CF、NDF、ADF消化率,Ca、P、Met、Cys表观消化率相关不显著.     

不同油料籽实对奶牛瘤胃代谢及养分表现消化率的影响

试验以3头荷斯坦奶牛为研究对象,采用3×3拉丁方设计,探讨日粮中添加不同油料籽实(日粮脂肪含量均为6.5%)对奶牛瘤胃内纤毛虫数量、pH值、NH3-N和菌体蛋白浓度动态变化、干物质采食量及养分表观消化率的影响.3种籽实分别为葵花籽、胡麻籽、菜籽.结果表明:日粮中添加不同的油料籽实对奶牛瘤胃液纤毛虫数量动态变化影响差异不显著(P＞0.05);对瘤胃液pH值动态变化影响差异不显著(P＞0.05),且数值均在瘤胃发酵的正常范围之内;瘤胃液NH3-N浓度动态变化3组之间差异不显著(P＞0.05);对菌体蛋白浓度的影响差异不显著(P＞0.05);对奶牛干物质采食量的影响差异不显著(P＞0.05);对奶牛干物质表观消化率、中性洗涤纤维表观消化率的影响差异不显著(P＞0.05);粗脂肪和粗蛋白的表观消化率均为葵花籽组较高,与其他2组相比差异显著(P＜0.05),葵花籽组粗脂肪和粗蛋白的表观消化率分别为62.56%、64.92%,胡麻籽组和菜籽组的粗脂肪和粗蛋白表观消化率较低,但差异不显著(P＞0.05).     

盐藻粉、壳聚糖和VA对奶牛日粮中氮、钙与磷表观消化率的影响

试验主要通过研究壳聚糖、盐藻粉、VA对奶牛日粮中N、Ca及P表现消化率的影响,旨在为科学地确定奶牛日粮中壳聚糖、盐藻粉及VA的添加剂量提供理论依据.试验分两部分进行,试验一选用18头荷斯坦奶牛作为试验动物,随机分成壳聚糖组、盐藻粉组和对照组,每组6头,壳聚糖和盐藻粉在奶牛日粮中的添加剂量为15 g/(d·头)、9 mg/(d·头),对照组不添加.试验二选用24头荷斯坦奶牛作为试验动物,采用2×2随机试验设计分成4个处理组,各组在基础日粮中添加不同水平(110、165 IU/kg·BW)及处理(未处理、过瘤胃保护)的VA.2个试验的试验期均为60d,其中预饲期10d,正试期50d.试验结果表明,奶牛日粮中添加壳聚糖可以显著地提高日粮N、P的表现消化率,降低Ca的表观消化率(P＜0.05).盐藻粉可以显著地提高日粮中N的表现消化率(P＜0.05).奶牛日粮中添加高剂量( 165 IU/kg·BW)的VA及过瘸胃保护的VA对日粮N、P、Ca的表观消化率无显著的影响,但N、P表现消化率有增加的趋势,Ca的表观消化率有降低的趋势.     

酿酒酵母培养物对泌乳奶牛生产性能、营养物质表观消化率及血清指标的影响北大核心CSCD

本试验旨在研究酿酒酵母培养物对泌乳奶牛生产性能、营养物质表观消化率及血清生化和免疫指标的影响。选取产奶量、胎次和泌乳天数相近的健康荷斯坦泌乳奶牛45头,随机分成3个组,每组15个重复,每个重复1头牛。对照组饲喂基础饲粮组,试验Ⅰ组和试验Ⅱ组分别在基础饲粮中添加精料量1%和2%的酿酒酵母培养物。预试期10 d,正试期60 d。结果表明:1)试验Ⅱ组产奶量极显著高于对照组和试验Ⅰ组(P<0.01);试验Ⅰ组产奶量较对照组提高了0.36 kg/d,但差异不显著(P>0.05)。2)试验Ⅰ组和试验Ⅱ组的干物质采食量较对照组分别提高了0.22和0.46 kg/d,但差异不显著(P>0.05);各组之间乳成分和饲料转化效率差异不显著(P>0.05)。3)试验Ⅰ组和试验Ⅱ组干物质表观消化率显著高于对照组(P<0.05);试验Ⅱ组粗蛋白表观消化率显著高于对照组(P<0.05);各组之间中性洗涤纤维和酸性洗涤纤维表观消化率差异不显著(P>0.05)。4)试验Ⅰ组和试验Ⅱ组丙血清氨酸转移酶活性极显著低于对照组(P<0.01),试验Ⅱ组血清免疫球蛋白G含量极显著高于对照组(P<0.01),各组之间其他各项血清生化和免疫指标差异不显著(P>0.05)。综上所述,饲粮中添加精料量2%的酿酒酵母培养物可显著提高泌乳奶牛生产性能,改善机体免疫能力,从而增加牧场经济效益。     

务川黑牛不同杂交组合的生长性能比较试验

为开发利用务川黑牛,试验选用安格斯牛、利木赞牛、西门塔尔牛对务川黑牛进行杂交改良,测量初生、6月龄、12月龄、18月龄、24月龄杂交一代牛的体尺和体重;屠宰24月龄杂交一代公牛,测量屠宰指标,比较不同杂交组合效果。结果:杂交一代牛的体长、体高、腰高、胸围、管围、体重在初生、6月龄、12月龄、18月龄、24月龄时均显著高于同期的纯种务川黑牛(P<0.05);日增重在0~6月龄比同期纯种务川黑牛高,差异显著(P<0.05);屠宰率和净肉率均比纯种务川黑牛高,差异显著(P<0.05)。结果表明:安格斯牛、利木赞牛、西门塔尔牛对务川黑牛生长性能和产肉性能均有较好的改良效果。     

苜蓿青贮料替代苜蓿青干草对奶牛生产性能及乳品质的影响

试验旨在探讨苜蓿青贮料替代不同比例苜蓿青干草对奶牛生产性能、乳品质、营养物质表观消化率、血液生化指标及经济效益的影响。选取体重、产奶量、胎次相近的健康泌乳中期中高产中国荷斯坦奶牛15头,随机分为3组,每组5个重复,每个重复1头牛。对照组饲喂4.0 kg苜蓿青干草,试验A、B组分别用4.4,8.8 kg苜蓿青贮料代替2.0和4.0 kg等干物质的苜蓿青干草,正试期64 d。结果表明,1)各组间干物质采食量差异不显著(P>0.05),B组产奶量显著低于对照组(P<0.05),A组与对照组、B组间差异不显著(P>0.05); 2)用50%,100%的苜蓿青贮料替代等干物质的苜蓿青干草,其乳蛋白、乳脂率、乳糖均有所改善,但只有B组的乳脂率显著高于对照组(P<0.05),其余指标各组间差异均不显著(P>0.05);3)A、B组与对照组的中性洗涤纤维表观消化率、钙表观消化率无显著性差异(P>0.05),A、B组间粗蛋白和磷表观消化率差异不显著(P>0.05),但是粗蛋白表观消化率均显著低于对照组、磷表观消化率均显著高于对照组(P<0.05);4)苜蓿青贮料替代苜蓿青干草其血清总蛋白、白蛋白、血尿素氮、血糖、二氧化碳结合力等指标没有显著性改变(P>0.05);5)试验A、B组经济效益均有所增加,其中A组的净增收益最高,为0.61元/(头·d)。综上,用4.4 kg苜蓿青贮料代替2.0 kg苜蓿青干草对中高产奶牛是适宜的,能提高其生产性能,改善乳品质,增加收益。     

Nutrient utilization by limit- and ad libitum-fed growing horses

Eighteen Quarter Horse and Paint weanling colts were assigned to two treatments, either limit or ad libitum feeding. Nutrient digestibilities of diets were evaluated between 6 and 12 mo, 12 and 18 mo and 18 and 24 mo of age. From 6 to 12 mo, energy digestibility (64 to 68%) was unaffected by feed intake level. Ad libitum-fed horses had energy digestibilities 9 to 10% greater (P less than .05) than limit-fed horses between 12 and 24 mo of age, but adjustment for DM intake removed these differences. Limit-fed, mature ponies used dietary energy similarly to growing horses from 6 to 18 mo of age, but they used digested dietary energy more efficiently (P less than .05) than young horses at 24 mo of age. Ad libitum-fed horses digested more (P less than .05) dietary protein than limit-fed horses between 12 and 24 mo of age, but adjustment for DM intake removed these differences. True digestibilities of dietary Ca were estimated at 71 to 42% among periods, whereas true digestibilities of dietary P ranged from 52 to 6%. Sufficient P was absorbed by all horses between 6 and 18 of age, but by 24 mo of age horses were in negative P balance despite an apparently adequate P intake. Using regression analyses, daily endogenous fecal Ca and P were predicted to be 36 and 18 mg/kg body weight, respectively.     

饲粮peNDF对奶公牛反刍、消化、生产性能及瘤胃发酵的影响

试验通过研究饲粮不同物理有效中性洗涤纤维（peNDF）含量对育肥奶公牛反刍、消化、生产性能和瘤胃发酵的影响,旨在为奶公牛生产中配制适宜peNDF含量的全混合日粮（TMR）提供依据。选择30头11月龄、体重（345.57±23.53） kg、健康的中国荷斯坦奶公牛（未阉割）,随机分为试验Ⅰ、Ⅱ和Ⅲ组,每组10头,分别饲喂8.00 mm孔径筛上物peNDF （peNDF_8.00）含量为12.40%、13.75%和14.85%的3种饲粮。结果表明：试验Ⅰ组奶公牛的饲粮采食次数显著高于Ⅱ和Ⅲ组（P<0.05）,试验Ⅱ和Ⅲ组反刍时间、每千克干物质和中性洗涤纤维反刍时间显著高于试验Ⅰ组（P<0.05）。3组间干物质采食量（DMI）、peNDF采食量、平均日增重（ADG）、料重比（F/G）及干物质（DM）、粗蛋白质（CP）、中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）、钙（Ca）和磷（P）表观消化率差异均不显著（P>0.05）。试验Ⅲ组瘤胃pH显著高于Ⅰ和Ⅱ组（P<0.05）,而丙酸浓度显著低于其他2组（P<0.05）。试验Ⅱ和Ⅲ组瘤胃乙丙比、乙酸和氨态氮（NH₃-N）浓度显著高于试验Ⅰ组（P<0.05）。在本试验条件下,3种不同peNDF_8.00水平饲粮对育肥奶公牛生产性能和养分表观消化率影响不显著,饲粮peNDF_8.00为13.75%和14.85%时,奶公牛反刍时间、瘤胃乙丙比、乙酸和NH₃-N浓度显著增加,可使奶公牛保持较佳瘤胃发酵性能。     

Renal clearance and fractional excretion of electrolytes over four 6-hour periods in cattle

Four consecutive 6-hour urine sample collections were performed on 7 healthy adult Holstein cows fed a diet of coastal Bermuda hay with ad libitum water consumption. Urine (via indwelling urinary catheter) and venous blood samples were collected at 6, 12, 18, and 24 hours. Total 24-hour urine production for the 7 cows ranged from 4,515 to 7,130 ml/d (mean +/- SD, 5,633 +/- 946 ml/d) or 0.02 to 0.04 ml/kg of body weight/d (mean +/- SD, 0.03 +/- 0.007 ml/kg/d). Renal clearance (C) of creatinine (Cr), sodium (Na), calcium (Ca), and magnesium (Mg) varied significantly (P less than 0.05) among individuals, but did not vary significantly among the four 6-hour collection periods. Clearance of chloride (Cl) and phosphorous (P) did not vary significantly either among individuals or among the four 6-hour periods. Clearance of potassium (K) varied significantly (P less than 0.05) among individuals and among the four-6-hour periods. Creatinine clearance was significantly (P less than 0.01) correlated with C(Cl), C(Ca), C(P), and C(Mg) when all data were considered. Significant (P less than 0.05) correlations were also found between C(Cl) and C(K), C(Ca), C(P), and C(Mg); between C(Ca) and C(P) and C(Mg); and between C(P) and C(Mg). Fractional excretion (FE) of Na, K, Cl, Ca, P, and Mg did not vary significantly among the four 6-hour periods. Fractional excretion of Na, Ca, and Mg (P less than 0.01) and K and P (P less than 0.05) varied significantly within individuals among the 6-hour periods.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of sex on antipyrine metabolism in cattle at different ages

The aim of this study was to determine the effect of sex on the metabolism of antipyrine by measuring the antipyrine plasma clearance as well as excretion of three major metabolites in urine in cattle of different ages. The experiment was carried out on 10 female and 10 male cattle of Black and White breed. The antipyrine test was carried out at 1, 2, 4, 6, 8, 12 and 18 months of age for each animal (single dose of 10 mg/kg antipyrine were given intravenously). The concentrations of antipyrine, 4-hydroxyantipyrine (4-OHA), 3-hydroxymethylantipyrine (HMA) and norantipyrine (NORA) were measured in plasma and urine by high performance liquid chromatography (HPLC). The apparent volume of distribution of antipyrine (aVd) decreased significantly between 1 and 18 months of age, but mean aVd values observed in males and females were not statistically different. The experimental period was characterised by a steady decrease (statistically significant) in antipyrine half-life (t1/2beta). These values did not differ significantly between males and females under 12 months. In 12 and 18 month-old animals the antipyrine half-life in the females was significantly shorter than in the males. The systemic clearance (Cls) of antipyrine increased significantly between 1 and 18 months of age. No significant differences were observed between systemic clearance of antipyrine in males and females under 12 months. In 12 and 18 month-old animals the Cls values were significantly higher in females than in males. Following intravenous administration, recovery of antipyrine and its three main metabolites increased significantly with age. These values did not differ significantly between males and females under 12 month of age. In 12 and 18 month-old females the excretion of 4-OHA and HMA in urine was significantly higher than in males at the same age. The excretion of NORA and unchanged antipyrine in males and females did not differ significantly. The partial clearances of antipyrine metabolites (Cl(m)) increased significantly between 1 and 18 months of age. No significant differences were observed between Cl(m) values in males and females under 12 months of age. In 12 and 18 month-old females the partial clearances of 4-OHA and HMA were significantly higher than in males. The clearance of NORA was significantly higher in 18 month-old females than in males. In conclusion, we report a sex-linked difference in plasma antipyrine clearance and urinary excretion of the main metabolites of antipyrine in cattle over 12 months of age, the females being the more active metabolizers.     

蒙贝利亚牛与荷斯坦牛在北方地区生长发育差异性比较

本研究对11头蒙贝利亚母牛和9头蒙贝利亚公牛的生长发育进行了跟踪测定,并与同期荷斯坦母牛的生长发育、产奶性能进行了对比分析。结果表明,蒙贝利亚母牛与荷斯坦母牛初生重无显著差异;4～18月龄,蒙贝利亚母牛体重均明显高于荷斯坦母牛同期体重,差异极显著（P〈0．01）。蒙贝利亚母牛与荷斯坦母牛日增重变化规律相似,lOB龄平均日增重最大,17月龄平均日增重最小。蒙贝利亚母牛各阶段体高、体长与荷斯坦母牛无显著差异,14月龄体高可达127cm,达到配种体高。蒙贝利亚母牛头胎305d产奶量为7241kg,对照组荷斯坦母牛头胎305d产奶量为9589kg,二者差异极显著（P〈0．01）。蒙贝利亚公牛初生重较大,至24月龄体重接近荷斯坦公牛同期体重。12~24月龄,荷斯坦公牛体高、体斜长、胸围均明显高于蒙贝利亚公牛,差异板显著（P〈0．01）;蒙贝利亚公牛初生重48kg,蒙贝利亚母牛初生重42kg,二者差异显著（P〈0．05）。蒙贝利亚公牛各阶段睾丸周径均显著高于荷斯坦公牛,差异极显著（P〈0．01）。     

Effects of calcium intake and parity on plasma minerals and bone turnover around parturition

Eight pregnant heifers (primiparous cows) and seven pregnant cows in their second, third and forth pregnancies (multiparous cows) were assigned to two groups and fed either a low calcium (Ca) diet (Ca, 0.46%) or a high Ca diet (Ca, 0.86%) ad libitum from 3 weeks before the expected calving date to 3 days after parturition. All cows were examined for a change in dry matter intake (DMI), plasma minerals and bone turnover around parturition. The dietary Ca level did not affect the DMI in both primiparous and multiparous cows. The DMI of primiparous cows was significantly lower than that of multiparous cows (P < 0.05) in both the low and high dietary Ca groups. The dietary Ca level did not affect the concentrations of plasma Ca, phosphorus, magnesium and parathyroid hormone throughout the experimental period. Plasma phosphorus in primiparous cows was significantly higher (P < 0.05) than that of multiparous cows around parturition. Plasma Ca and magnesium tended to be higher (P < 0.10) in primiparous cows. The dietary Ca level did not affect the plasma osteocalcin (OC) level measured as bone formation or the urinary deoxypyridinoline (DPD) excretion measured as bone resorption before parturition in both primiparous and multiparous cows. After parturition, the plasma OC level was lower than it was before parturition in multiparous cows fed a low Ca diet, and in primiparous cows. There were no significant differences in urinary DPD excretion between each group before and after parturition. Both the plasma OC level and urinary DPD excretion of primiparous cows were significantly higher than those of multiparous cows in both the low and high dietary Ca groups.     

喷浆玉米皮对肉兔生长性能、养分表观消化率及肉品质的影响

本试验旨在研究喷浆玉米皮对肉兔生长性能、养分表观消化率及肉品质的影响.试验选取39日龄伊拉幼兔300只,公母各占1/2,根据体重和性别随机分为5组(对照组及Ⅰ、Ⅱ、Ⅲ、Ⅳ组),分别饲喂含不同比例喷浆玉米皮(0、6％、12％、18％和24％)的试验饲粮,每组60个重复,每个重复1只兔.预试期5 d,正试期50 d.结果表...     

胎次和泌乳阶段对奶牛体细胞数和乳损失量的影响

通过奶牛生产性能（dairy herd improvement,DHI）测定体细胞数,探究奶牛的胎次及其不同泌乳阶段对其乳体细胞数（somatic cell count,SCC）和乳损失量的影响。通过对某养殖场泌乳期奶牛DHI的测定进行分析,结果表明：体细胞评分（somatic cell score,SCS）随奶牛胎次的增加而增加,但SCS在不同胎次的不同泌乳阶段表现有所不同。一胎牛SCS随着泌乳期的延长而增加,前期、中期与后期的SCS呈显著性差异（P＜0.05）;二胎牛与三胎牛SCS呈现相同变化规律,泌乳前期的SCS较泌乳中期高,而泌乳后期SCS显著高于前2个泌乳阶段（P＜0.05）。乳损失量随胎次的增加整体呈现增加趋势,且泌乳早期和泌乳后期乳损失量高于泌乳中期。