热应激影响荷斯坦奶牛泌乳机制的研究进展

奶牛在极端热环境下会产生热应激反应,导致奶牛泌乳量降低、乳品质下降。本文从热应激诱导乳腺氧化应激及影响机体激素代谢、抑制乳成分合成角度综述了热应激影响奶牛泌乳的机制,并对补饲添加剂缓解热应激的效果进行总结,以期为进一步探究热应激机理及寻求有效、合理的缓解措施提供理论依据。     

玉米处理方法对泌乳牛产乳性能和养分消化的影响

试验采用4×4拉丁方设计,研究玉米处理方法对荷斯坦中期泌乳牛产乳性能和养分消化的影响。四种处理组分别为对照组、25%煮玉米组、50%煮玉米组和50%泡玉米组。日粮中玉米全部粉碎,平均粒度为1.4mm。玉米处理比例为处理玉米占日粮总玉米的百分比。结果表明,玉米处理方法不影响乳成分含量。25%煮玉米趋于提高原乳及FCM(标准乳)产量(P>0.05)。50%煮玉米提高原乳产量4.4%(P>0.05)和FCM产量6.8%(P<0.05)。50%泡玉米可提高原乳和FCM产量9.3%～9.4%(P<0.01)。玉米处理方法不影响DM、OM、能量、CP和淀粉全消化道表观消化率,以及粪便含水率。25%煮玉米分别降低NDF和ADF消化率18.0%和9.6%(P<0.05),50%煮玉米分别降低NDF和ADF消化率18.4%和20.7%(P<0.05)。50%泡玉米降低NDF和ADF消化率为16.4%(P<0.05)和8.6%(P>0.05)。玉米处理方法不影响午饲前血液中葡萄糖和尿素氮含量。     

热应激对奶牛繁殖性能的影响研究进展

环境温度、湿度和光照周期都会对奶牛的繁殖性能造成影响。夏季奶牛采食量减少可能会影响奶牛的能量平衡,或导致下丘脑-垂体-卵巢轴功能紊乱,进而降低卵母细胞、胚胎和卵泡的质量,导致奶牛繁殖性能降低。本文就夏季热应激对奶牛繁殖性能的影响做一综述。     

科学认识阴离子盐综合防治奶牛产后病

1围产期——牛场利润的关键控制点 围产期是奶牛一生中最为关键的阶段。产犊前后，奶牛经历了营养、生理和代谢等诸多方面的极大应激，导致机体抵抗力下降。此期间饲养管理不善不仅使牛易患代谢性疾病，也易感染传染性疾病（如环境性乳房炎等）。如果采取有效措施预防围产期疾病，整个泌乳期疾病的发病率将会降低90％（Goff，1998），产奶量也将有大幅提高。所以“围产期”是牛群生产力、牛场利润的“关键控制点”。     

不同剂量的小肽制剂对奶牛产奶性能的影响

大量的研究表明,不同来源的饲料中尽管氨基酸组成相同,但利用率存在明显差异。动物对饲料中氨基酸的利用率并不完全受单一限制性氨基酸含量的影响。当动物采食按理想氨基酸平衡配制的纯合日粮或氨基酸平衡的低蛋白质日粮时,并不能达到理想的最佳效果。动物对蛋白质的需要不能完全由游离氨基酸来满足,为了达到最佳生产性能,必须需要一定数量的肽———特别是小肽(由2～3个氨基酸构成)。Armstead等研究指出,肽是瘤胃微生物蛋白质合成的重要底物。研究通过对奶牛的饲养对比试验,探讨小肽制剂对奶牛泌乳性能的影响,为小肽制剂在奶牛生产中的应…     

Growth and Reproductive Performance of Holstein Heifers as Affected by Ruminal Degradation of Supplemental Protein

Reproductive performance of primipa-rous and multiparous dairy cows has been improved by increasing the proportion of undegraded intake protein (UIP) in the diet, especially when fish meal (FM) was supplemented. This positive response has not been documented with dairy heifers, in general, or under grazing conditions, in particular. Therefore, the objective of this study was to determine the effects of increasing the UIP level in the supplement on growth and reproductive performance of Holstein heifers in a 104-d grazing trial. A total of 63 heifers (BW ± SD = 317 ± 14 kg) were allotted at random to nine paddocks (7 heifers each) to allow for three replications (paddocks) per treatment. One heifer was later found as a freemartin and, therefore, was excluded from the study. The pasture [81.8% OM, 11.1% CP, and 61.1% NDF (DM basis)] was composed mainly of tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis) with a minor proportion of other forages [e.g., white clover (Trifolium repens)]. The heifers were group-fed one of three supplements (1.9 kg DM/d per heifer) based on corn and dry molasses; the supplements also contained soybean meal, FM, or both protein sources to allow for 0, 50, or 100% of supplemental CP from FM. The heifers had ad libitum access to water and mineral-vitamin-molasses blocks. They were synchronized for estrus [two injections (5 mg each of prostaglandin F₂) on d 45 and 56], artificially inseminated on d 59, allowed to graze without the supplement on d 80, and tested for pregnancy via rectal palpation on d 104. Over the 80 d of feeding the supplements, there were no differences (P>0.05) among treatments for ADG (0.87, 0.82, and 0.94 kg), gain-to-supplement ratio (0.42, 0.39, and 0.46), or conception rate (28.6, 38.1, and 35.0%). The absence of significant gain or reproductive responses in this study might have been due to the poor quality forage, the limited amount of supplement fed, or both. Low quality forage also can negatively affect reproduction by decreasing efficiency of ruminal N utilization caused by limited energy supply.     

Influence of Postpartum Cloprostenol Treatment in Sows on Subsequent Reproductive Performance under Field Conditions

During the previous decade several studies focused on postpartum treatment with prostaglandin for improvement of reproductive performance in sows. The aim of the study was to investigate the effect of administration of a prostaglandin F_{2 α} (PGF_{2 α} ) analogue in sows within 24–48 h after farrowing on sow and litter performance. In five commercial farms, the sows were randomly assigned to either treatment A (2 ml cloprostenol, Planate^IM) or treatment B (2 ml physiological saline solution, i.m.). Fifteen per cent of all sows were at random selected for progesterone analysis. Litter performance was assessed by measuring pre-weaning mortality and average daily weight gain (ADG). Sow performance was assessed by measuring weaning-to-oestrus interval (WOI), the percentage of sows returning to oestrus and litter size during subsequent farrowing. Administration of a PGF_{2 α} analogue within 24–48 h postpartum had no effect on the rate of progesterone decline measured over 24 h compared with that of the controls. Litter performance and WOI were not affected by treatment. The subsequent litter size in sows of parity seven and more showed a significant difference of 1.98 piglets (p < 0.01) between both groups, to the benefit of the cloprostenol group. In conclusion, administration of a synthetic PGF_{2 α} analogue, cloprostenol, within 24–48 h after farrowing improved litter size at next farrowing in older (≥7 parity) sows.     

热应激对泌乳盛期奶牛的采食量和消化率的影响

[目的]探讨热应激对奶牛采食量和饲料中营养物质消化率的影响。[方法]通过采用单因子水平随机设计。[结果]奶牛热应激时采食量显著下降,在轻微和中度热应激期采食量分别下降3.65%和13.46%;营养物质的消化率也显著下降(P0.05),奶牛在轻度和中度热应激期粗脂肪的消化率分别降低了6.17%、13.03%;钙的消化率分别降低了25.09%、34.97%;磷的消化率分别降低了22.77%、36.27%。[结论]奶牛热应激时采食量显著下降(P0.05);饲料中营养物质消化率粗脂肪、钙、磷的消化率与非热应激期相比,差异显著(P0.05)。     

新疆不同季节荷斯坦干乳牛与泌乳牛甲烷24小时排放及排放量变化的研究

试验于2011年7月～2012年7月在同一栋牛舍内对20头干乳牛和20头泌乳牛分别进行了四季的甲烷排放量测定,在每个季节的季初、季中、季末测定三次,每次测定24h.结果表明:干乳牛春季、夏季、秋季、冬季的CH4排放量分别为228.73g/(头·d)、234.09g/(头·d)、218.35g/(头·d)、178.22g/(头·d).泌乳牛春季、夏季、秋季、冬季的CH4排放量分别为304.49g/(头·d)、314.43g/(头·d)、292.11g/(头·d)、238.07g/(头·d).干乳牛与泌乳牛在夏季CH4排放量最多,在冬季CH4排放量最少.泌乳牛比干乳牛CH4排放量高,平均高出1.3～1.4倍.     

不同能量物质对泌乳奶牛产奶性能的影响

本文探讨了不同能量补充物质对泌乳奶牛生产的影响。,以麸皮作对照,用全棉籽、膨化全脂大豆和脂肪酸钙作为能量补充物质,35d试验结果显示,奶牛产奶量分别提高了6．7％、14．4％和18．2％．．乳脂肪分别提高19．（／9％、11．82％和11．21％、经济效益分别比对照组提高4．20、5．36和8．72．＇L／（头·d）!试验表明,全棉籽、膨化全脂大豆和脂肪酸钙作为能量补充物质,可减轻夏季热应激,提高牛奶产量和牛奶品质,尤以脂肪酸钙效果最佳。     

热应激对猪繁殖性能的影响及防止措施

温度对种猪的繁殖性能具有重要的影响,根据相关文献阐述热应激对种母猪发情、受胎率、胚胎成活率、产仔数以及种公猪繁殖性能的影响,提出了控制热应激对种猪繁殖性能影响的具体措施。     

Factors Affecting Synchronization and Conception Rate after the Ovsynch Protocol in Lactating Holstein Cows

Objectives were to evaluate risk factors affecting ovulatory responses and conception rate to the Ovsynch protocol. Holstein cows, 466, were submitted to the Ovsynch protocol [day 0, GnRH‐1; day 7, prostaglandin (PG) F_2α; day 9, GnRH‐2] and 103 cows were inseminated 12 h after GnRH‐2. Information on parity, days in milk at GnRH‐1, body condition, milk yield, exposure to heat stress, pre‐synchronization with PGF_2α and the use of progesterone insert from GnRH‐1 to PGF_2α was collected. Ovaries were scanned to determine responses to treatments. Overall, 54.7%, 10.6%, 2.2%, 81.1%, 9.0%, 91.5% and 36.9% of the cows ovulated to GnRH‐1, multiple ovulated to GnRH‐1, ovulated before GnRH‐2, ovulated to GnRH‐2, multiple ovulated to GnRH‐2, experienced corpus luteum (CL) regression and conceived, respectively. Ovulation to GnRH‐1 was greater in cows without a CL at GnRH‐1, cows with follicles >19 mm and cows not pre‐synchronized with PGF_2α 14 days before GnRH‐1. Multiple ovulations to GnRH‐1 increased in cows without CL at GnRH‐1 and cows with follicles ≤19 mm at GnRH‐1. Ovulation before GnRH‐2 was greater in cows without CL at PGF_2α. Ovulation to GnRH‐2 increased in cows that received a progesterone insert, cows with a CL at GnRH‐1, cows with follicles not regressing from the PGF_2α to GnRH‐2, cows with larger follicles at GnRH‐2, cows that ovulated to GnRH‐1 and cows not pre‐synchronized. Multiple ovulations after GnRH‐2 increased in cows with no CL at GnRH‐1, multiparous cows and cows that multiple ovulated to GnRH‐1. Conception rate at 42 days after AI increased in cows with body condition score > 2.75 and cows that ovulated to GnRH‐2. Strategies that optimize ovulation to GnRH‐2, such as increased ovulation to GnRH‐1, should improve response to the Ovsynch protocol.     

两种复合预混料对热应激奶牛产奶性能的影响

试验目的是观测两种不同配方的复合预混料在热应激条件下对中国荷斯坦奶牛产奶性能的影响。试验分为两组,每组7头,分别饲喂对照组(普通型预混料)和试验组(含抗热应激预混料)日粮,两种日粮基础配方相同,含预混料不同,平均温湿度指数(THI)为80.18±5.43。经32d的饲养试验表明:1、抗热应激功能型预混料较普通型预混料显著提高产奶量9%(P<0.05);2、两组间平均乳脂率、乳蛋白率、乳糖和非脂乳固体(SNF)无显著差异(P>0.05);3、试验期间平均产奶量与THI呈双曲线负相关关系(对照组Rc2=0.5365;试验组RT2=0.4894)(P>0.05)。     

不同硒源对泌乳中期荷斯坦奶牛生产性能、抗氧化性能及营养物质表观消化率的影响

本试验旨在研究不同硒源对泌乳中期荷斯坦奶牛生产性能、抗氧化性能及营养物质表观消化率的影响。试验选取45头产奶量、胎次、泌乳日龄相近的健康中国荷斯坦奶牛,随机分成3组,每组15头。对照组饲喂不添加硒的基础饲粮,无机硒(SS)组饲喂基础饲粮+0.3 mg/kg亚硒酸钠,有机硒(SO)组饲喂基础饲粮+0.3 mg/kg蛋氨酸硒羟基类似物。试验期91 d,其中预试期7 d,正试期84 d。结果表明:1)饲粮中添加硒对奶牛的干物质采食量、产奶量及乳成分没有显著影响(P0.05)。2)与对照组相比,SO组血清总抗氧化能力和谷胱甘肽过氧化物酶活性显著升高(P0.05),血清丙二醛含量显著降低(P0.05),但SS组以上指标与对照组没有显著差异(P0.05)。3)各组中性洗涤纤维、酸性洗涤纤维和干物质的表观消化率差异不显著(P0.05)。与对照组相比,SO组有机物、粗蛋白质及粗脂肪的表观消化率显著提高(P0.05);SS组有机物和粗蛋白质的表观消化率提高,但差异不显著(P0.05)。综上所述,饲粮添加不同硒源对泌乳中期荷斯坦奶牛的生产性能没有影响,但与对照组相比,硒添加组的抗氧化性能和营养物质的表观消化率提高,而且SO组的效果明显优于SS组。     

溴隐亭与生殖激素配合诱导产后泌乳羊发情的效果试验

为了研究比较不同方法诱导泌乳期新疆细毛羊的发情效果,对泌乳60 d的母羊进行断奶,并用溴隐亭和孕激素制成的复合阴道缓慢释放装置配合促性腺激素进行诱导发情,处理期间测定促卵泡素(FSH)、促黄体素(LH)、促乳素(PRL)、孕激素(P4)和雌激素(E2)的浓度,研究结果表明,将溴隐亭和孕激素做成的溴隐亭炔诺酮复合剂缓慢释放装置,经阴道放置比较2种不同剂量的溴隐亭复合装置使绵羊的发情率分别为100%和56.7%。使用溴隐停和孕激素并配合促性腺激素能有效诱导泌乳期新疆细毛羊发情。     

舍外温湿度对荷斯坦奶牛生产性能及酶活性影响的研究

以荷斯坦奶牛为试验对象,研究不同环境温度、湿度对奶牛生产性能及血液乳清酶活性的影响.研究结果表明随着环境温度的季节性下降和舍内湿度的升高,血清及乳清ALT、AST和ALP活性下降;血清和乳清中CK活性升高;血清LDH活性升高,乳清LDH活性降低;建议舍内温度5.5℃±0.5,相对湿度80%为宜.     

热应激对奶牛繁殖力的影响及应对措施

炎热的夏季会导致奶牛的繁殖力下降,其原因是由于热应激引起动物机体一系列的异常反应所致。本文通过总结近十几年国内外的研究成果,从内分泌、配子产生和胚胎发育等方面论述了热应激对奶牛繁殖力的影响及可能存在的内在机制,并针对这些影响提出了一系列在奶牛生产中用于缓解热应激和提高奶牛繁殖力的措施,包括常用的奶牛物理降温法、日粮调配、耐热性奶牛的培育,以及具有广阔前景的生物技术等。     

舍外温湿度对荷斯坦奶牛生产性能及酶活性影响的研究

以荷斯坦奶牛为试验对象,研究不同环境温度、湿度对奶牛生产性能及血液乳清酶活性的影响。研究结果表明:随着环境温度的季节性下降和舍内湿度的升高,血清及乳清ALT、AST和ALP活性下降;血清和乳清中CK活性升高;血清LDH活性升高,乳清LDH活性降低;建议舍内温度5.5℃±0.5,相对湿度80%为宜。     

热应激对动物生殖机能的影响及其作用机理

温度对动物生殖机能具有重要的影响,本文分别阐述热应激对雌性动物发情、受胎率、胚胎成活率、产仔数以及对雄性动物繁殖性能的影响,并提出了热应激对动物生殖机能影响的可能作用机理。     

不同脂肪源对哺乳母猪繁殖性能及养分消化率的影响

试验旨在研究哺乳母猪日粮中添加不同脂肪源对母猪繁殖性能和饲粮养分消化率的影响。选取第3胎次PIC母猪30头,随机分配到3个处理,即对照组、2%大豆油组和2%脂肪粉组,每个处理10个重复。试验从母猪分娩开始,到仔猪21日龄断奶时结束。结果表明:与对照组相比,脂肪粉组第3周平均日增重(ADG)和第3周窝增重分别提高了26.29%(P<0.05)和23.93%(P>0.05),大豆油组分别提高了19.72%(P>0.05)和17.85%(P>0.05)。且脂肪粉组的提高幅度最大。由此可知,饲粮中添加不同脂肪源可提高饲粮养分消化率,改善哺乳仔猪的生产性能,且脂肪粉优于大豆油。