环境因素对散养奶牛的繁殖行为和繁殖性能的影响

1991～1994年在洛阳市奶牛场连续观察散养与栓系饲养体制下奶牛的发情表现、发情地点及每日的发情时间分布,统计每月的受胎率和奶牛的产后首次配种时间.结果表明在散放饲养条件下,奶牛发情明显,发情行为期长;夏、冬季的受胎率低于春、秋季,明显地受温度的影响和五项气象因素的综合作用;五项气象因素对产后首次配种时间的综合影响显著.     

定时输精程序（Ovsynch／TAI）在奶牛繁殖上的应用效果

应用生源结合诱情素的定时输精程序。对不发情、卵巢静止的奶牛以及产后60～75天发情正常的奶牛进行试验，结果表明：不发情奶牛应用定时输精程序处理后，情期受胎率为74％，而正常配种的情期受胎率为49．8％．提高24．2个百分点；对卵巢静止的奶牛应用定时输精程序处理后有效率为97．2％，情期受胎率为64％：对产后60-75天发情正常的奶牛应用定时输精程序处理后情期受胎率为68．6％，按正常方式配种的奶牛情期受胎率为45．6％，情期受胎率提高23个百分点。结论：定时输精程序在奶牛繁殖上的应用具有明显效果．适合国内饲养条件下任何奶牛场使用。     

奶牛的妊娠与流产

1影响受胎率的因素 影响奶牛受胎率的因素很多,包括精液品质、母牛生殖道健康状况、奶牛饲料及营养状况、饲养管理情况、配种季节、气候环境因素和配种员的技术水平等。在此主要分析影响奶牛受胎率的发情、配种因素。     

影响奶牛产后情期受胎率因素的调查

对查哈阳农场太阳湖分场场区繁育点1997年配种年度奶牛产后配种记录的整理,调查和分析了568头奶牛产后配种记录,情期受胎率为51．7％。1奶牛产后第1次配种时间与情期受胎率568头奶牛产后第1次配种时间平均为85．7天,情期受胎率为51．7％。详见表1。表1奶牛产后第三次配种时间与情期受胎率从表1看出,产后第1次配种时间除少于50天者,情期受胎率无显著差异。产后50天以内情期受胎率较低,产后70～89天情期受胎率较高,这时期是奶牛产后第1次配种的理想时间。对产后3个月以上不发情奶牛应进行检查,对症治疗,加强饲养管理,使奶牛产后尽快…     

奶牛繁殖的几个问题

繁殖技术在奶牛饲养管理中起着举足轻重的作用。本文想谈谈国外关于奶牛发情鉴定、受胎率、配种时间、产后发情及配种时间、人工授精部位等几个繁殖问题供参考。 (一)发情鉴定通常是借助外部观察或伴以试情来确定牛是否发情,这虽是一个最基本的方法,但对牛多而配种     

奶牛产后常见繁殖疾病防控

随着奶牛行业发展,牧场走规模化、集约化道路,追求高产量同时,都关注奶牛产后是否能尽快配种并受孕,从而缩短产犊间隔,减少饲养成本。新产牛护理中子宫保健是指奶牛产后子宫恢复到未孕时形态和功能的生理过程。产后子宫保健的过程和子宫恢复的状态决定奶牛产后第1次发情的受胎率,即首配受胎率。奶牛产后如果子宫复旧不全,会多发繁殖疾病,严重影响奶牛首配受胎率。由于产后发情配种未怀孕则导致受孕时间推迟,产犊间隔增加,意味着空怀饲养天数增加和牧场经济效益降低,所以牧场应时刻关注奶牛产后子宫护理工作及常见繁殖疾病的防控。     

宝鸡地区荷斯坦奶牛发情、排卵及授精效果的比较观测

对宝鸡地区荷斯坦奶牛发情周期排卵时间、授精效果进行了调查，并对其影响因素作了分析研究。研究结果：不同产犊季节对产后第一次发情时间有显著影响，青年牛与成年牛发情后排卵时间有显著差异。产后第一、二次与三次以上发情输精受胎率有显著差异；产后母牛用药物处理和不处理，授精效果差异显著。表明，在奶牛产后子宫正常情况下，在第一、二情期授精效果最好；发情周期在19－23d受胎率提高；排卵8h内输精、受胎率最高。     

谈荷斯坦奶牛的排卵规律

受胎率的高低与育种员能否掌握适时配种密切相关，而适时配种又取决于育种员对奶牛排卵规律的掌握。奶牛的排卵速度受季节、温度、年龄、卵泡大小、子宫状况、发情症状、饲养方式等因素影响。准确地把握排卵规律是提高情期受胎率的重要措施。     

谈荷斯坦奶牛的排卵规律

受胎率的高低与育种员能否掌握最佳配种时机密切相关，而适时配种又取决于育种员对奶牛排卵规律的掌握。奶牛的排卵速度受季节、温度、年龄、卵泡大小、子宫状况、发情症状、饲养方式等因素影响。准确地把握排卵规律是提高情期受胎率的重要措施。     

采取产后子宫药物净化程序对提高奶牛受胎率的效果

子宫内膜炎和子宫积脓，是奶牛产后易患的两种生殖系统疾病。其诱发原因，一是产后奶牛发情进行人工授精时，输精器械消毒不严；二是奶牛难产或胎衣不下，需进行人工助产或人工剥离胎衣时，因处理操作不当，而继发产后子宫细菌感染。为此，如不及时进行治疗，将会严重影响产后奶牛三率：即情期受配率、受胎率和产后犊牛的成活率，致使饲养奶牛的经济效益降低。为了防止产后奶牛生殖道系统各种炎症疾患，提高奶牛的三率，笔者近年来，在奶牛配种工作实践中，经过反复试验，终于摸索出了一套卓有成效的药物净化子宫治疗程序，对提高奶牛受胎率…     

Characterization of Influence of Manure Handling System and Feeding on the Level of Ammonia Release Using a Simple Method in Cow Houses

The effects of manure handling system and feeding of dairy cows were studied using a simple method to analyse the level of ammonia release in cow stables. Two ratios based on the balances of ammonia and sensible heat, and ammonia and carbon dioxide, respectively, in animal houses were determined and considered to give characteristic levels of the release of ammonia in relation to the animal density independently of the ventilation rate. This required measurements of ammonia, carbon dioxide and temperature with hand-held instruments in the buildings and in outside air. In total, 34 dairy herds were investigated in the south of Sweden. The results clearly demonstrated higher release of ammonia from free stall barn with liquid manure than from conventional tie stall barn with solid manure. There was a clear effect of the content of crude protein, gram per kg dry matter, in the total feed ration on ammonia release in tie stall barn with liquid manure.     

Reproduction in three genetic lines of dairy cattle housed a total confinement system.

Dairy cattle of three genetic lines maintained year round in total confinement (either in loose housing or tie stall barn) were monitored for estrous cycle activity and reproductive performance. Only 54% of the 492 cows calving over a 12 month interval were observed in estrus at least once between parturition and day 55 postpartum. There was a significant genetic line by barn interaction in the detection of estrus mainly because more cows of the Ayrshire line were observed in estrus in the tie stall barn (75%) compared to cows of the same line in the loose housing barn (48%). Month of calving had no effect on the subsequent detection of estrus. Conceptions to either first, second, third or fourth and greater services were 43, 44, 43 and 37%, respectively. Cows housed in the loose housing barn had significantly more days open than cows in the tie stall barn. Season of calving had no effect on the subsequent reproductive performance. Failure to detect estrus was the major problem for not obtaining a 12 month calving interval.     

半胱胺盐酸盐对泌乳中期热应激奶牛生产性能的影响

本试验旨在研究散栏式饲养方式下,饲喂半胱胺盐酸盐对泌乳中期热应激奶牛生产性能的影响。选择48头健康荷斯坦奶牛[体重(562.25±37.85)kg,泌乳天数(123.64±10.67)d,胎次(1.23±0.42)胎,日产奶量(26.58±1.58)kg],根据体重、泌乳天数、产奶量相同或相近的原则,随机分成4组(每组12头),对照组饲喂基础饲粮,试验组分别在基础饲粮中添加半胱胺盐酸盐3、15、30 g/kg。预试期12 d,正试期30 d。结果显示:随半胱胺盐酸盐添加剂量的增加,奶牛呼吸频率和直肠温度呈显著的线性降低(P0.05);干物质采食量、乳脂较正乳产量、能量校正乳产量、乳脂率、乳蛋白率均呈先升高后降低的显著的二次曲线变化(P0.05),并且以添加3 g/kg组的效果较好;正试期末,3、15 g/kg组血清甲状腺素浓度显著低于对照组(P0.05),15 g/kg组血清皮质醇浓度显著高于对照组(P0.05)。结果提示,半胱胺盐酸盐能有效缓解散栏饲养的泌乳中期奶牛热应激,提高产奶量和乳品质,本试验条件下,饲粮中添加3 g/kg半胱胺盐酸盐较为适宜。     

Practical aspects of the fertility of dairy cattle

To establish sustainability in the dairy industry, it is important that cows become pregnant at a biologically optimal time and at an economically profitable interval after calving. In this review, the results obtained from Holstein cattle in an experimental herd for dairy research are summarized. First, the effect of age at first calving of heifers on productive and reproductive performance was examined. A reduction in calving age from 25.1 to 21.5 months with the same growth rate during the first 12 months after birth had no negative effects on the heifers' performance. Second, the postpartum follicular dynamics of lactating cows were traced in relation to their fertility, and the emergence and fate of cystic ovarian follicles were examined. The premature initiation of ovarian activity does not always improve the fertility of cows as indicated by the number of days open. Third, the occurrences of anestrous ovulation during the early postpartum period were analyzed with reference to the frequency of reversion to anestrus. The premature onset of estrous activity also did not improve fertility, and relapse back into anestrus after the onset of the estrous cycle often occurred during the breeding period. Fourth, some indices for the occurrence of postpartum reproductive events were evaluated as an indicator of the reproductive performance of lactating cows. The milk yield and percentage of body weight loss could be indicators for reproductive events. Finally, the potency of a pedometry system for the detection of typical and atypical estrous behaviors of heifers and lactating cows was evaluated in terms of efficiency and accuracy. The location of the pedometers and housing conditions for the animals affected the estrus detection of the system. These results represent the reproductive potential of modern high-yielding dairy cattle and provide a baseline to evaluate their reproduction.     

Seasonal variation of the lying and standing behavior indexes of dairy cattle at different daily time periods in free‐stall housing

The lying and standing behavior of dairy cattle reveal whether dairy cattle housing is appropriate to cow comfort. Lying and standing behavior indexes, such as cow comfort index (CCI), cow stress index (CSI) and stall usage index (SUI) are often used as an indication of animal welfare. This study was performed to determine the seasonal and hourly variation of cow behavioral indexes at different daily time periods (DTP) and evaluate appropriate DTP better representing daily behavioral activity of dairy cattle in free‐stall housing (FHS) in Konya, Turkey. Animal behaviors were videotaped for a total of 24 days (576 h) over four seasons in a FHS at a commercial dairy farm from November 2007 to March 2009 using continuous video data (24 h per day). The behaviors of cows in the barn were evaluated using 60‐min scan sampling. All phenotypes were evaluated on an hourly basis during the experimental period. The results show how these indexes can be accurately evaluated by analyzing video recordings taken on DTP between 08.00–15.00 and 19.00–24.00 hours for autumn and summer and 10.00–12.00 and 20.00–22.00 hours for spring, instead of continuous observation (r > 0.93, P < 0.01). Consequently, the evaluated method provides saving time and labor to accurately analyze cow behavior instead of observations over a long time.     

Physiological mechanisms controlling anestrus and infertility in postpartum beef cattle

Postpartum infertility is caused by four factors: general infertility, lack of uterine involution, short estrous cycles and anestrus. The general infertility component is common to any estrous cycle and reduces potential fertility by 20 to 30%. Incomplete uterine involution prevents fertilization during the first 20 d after calving but is not related to anestrus. Short estrous cycles prevent fertility during the first 40 d after calving by causing the cow to return to estrus before pregnancy recognition occurs. Anestrus is the major component of postpartum infertility and is affected by several minor factors: season, breed, parity, dystocia, presence of a bull, uterine palpation and carryover effects from the previous pregnancy as well as two major factors: suckling and nutrition. These major factors have direct effects on anestrus but also interact with one or more other factors to control postpartum anestrus. Physiological mechanisms associated with anestrus involve blockage of the GnRH "pulse generator" in the hypothalamus, but other pathways also must be involved because bypassing the pulse generator is not an effective treatment for all cows. The primary cause of anestrus probably is different for different stages of anestrus. The mediating mechanisms for anestrus are not involved with prolactin, oxytocin, the adrenal or direct neural input from the mammary gland but are at least partially involved with blood glucose and the endogenous opioid peptide system. Management options to decrease the impact of anestrus and infertility include: 1) restrict breeding season to less than or equal to 45 d; 2) manage nutrition so body condition score is 5 to 7 before calving; 3) minimize effects of dystocia and stimulate estrous activity with a sterile bull and estrous synchronization; and 4) judicious use of complete, partial or short-term weaning.     

定时输精对奶牛第一情期受胎率的效果分析

[目的]探讨不同月份和精液类型对利用定时输精程序处理奶牛后第一情期受胎率的影响.[方法]选择93头产后60 d以上不发情和产后配1～3次仍未受胎的奶牛,不检查卵巢直接利用激素生源2+1进行同期发情处理.1～3月份处理41头奶牛,6～8月份处理52头;其中,利用性控精液配种58头,常规精液配种35头.[结果]表明:经定时...     

Reliability of estrous detection in Holstein heifers using a radiotelemetric pedometer located on the neck or legs under different rearing conditions

To evaluate the efficiency and accuracy of estrous detection using a new pedometry system that can measure the hourly activity of cattle, pedometers were attached to the neck and the hind legs of 15 Holstein heifers. Heifers were reared in pasture for grazing, an open paddock, or in a tie-stall barn (an additional pedometer was attached to a front leg of each of these heifers). The most recent 24 h-total number of steps was compared for each 1 h-interval with the mean value of the preceding days during the reference period (RP). The neck pedometer detected all 10 instances of estrous activity (100%) for the grazing heifers at 1.3 times the thresholds value for a 5-day RP but with only 32% accuracy. The hind leg pedometer, however, obtained 100% efficiency and 83% accuracy at 1.4 times the threshold value for a 7-day RP. The efficiencies and accuracies in detecting 12 instances of estrous activity under the paddock condition were 92 and 65% (neck, 1.3-fold, 7-day RP) and 92 and 100% (hind leg, 1.6- or 1.7-fold, 7-day RP), respectively. Under the tie stall condition, the neck pedometers detected 92% of 23 instances of estrous activity with 34% accuracy (1.2-fold, 3-day RP), and the efficiencies and accuracies of the leg pedometers were 78 and 78% (hind leg, 1.4-fold, 4- or 6-day RP) and 87 and 83% (front leg, 1.4-fold, 7-day RP), respectively. Prediction of ovulation time was more precisely with the leg pedometers than with those under the tie stall conditions. Our preliminary results indicate that this new pedometer system has practical value for estrous detection in heifers under different rearing conditions, which affect the criteria required for detection. Furthermore, they also indicate that a leg pedometer can reliably detect estrus and that a neck pedometer may only be capable of detecting estrus under paddock rearing conditions.     

北方寒区散栏育肥牛舍配套工艺及环境评价

[目的]为了发挥肉牛在北方冬季环境条件下其最佳生产潜力。[方法]设计了散栏保温牛舍和开放式散栏牛舍2种类型畜舍形式,分别在牛舍中心距离地面0.5m和1.5m处进行温度、湿度测定。[结果]舍内平均湿度为100%,最低温度为-0.6℃,育肥牛平均日增重达到0.83kg/头。[结论]散栏式牛舍冬季湿度大、温度低,牛只采食自由性较大,可改为采用颈杠式,固定床位,设有分隔栏方式,减少温湿度蒸发,同时可避免争食现象。     

Relationships Between the Appearances and Changes of Estrous Signs and the Estradiol-17β Peak,Luteinizing Hormone Surge and Ovulation During the Periovulatory Period in Lactating Dairy Cows Kept in Tie-stalls

Lactating Holstein-Friesian cows kept in tie-stall barn were used as subjects in this study. Rectal examination, ultrasonography and blood sampling were conducted every other day and then daily after the day on which diameter of the corpus luteum decreased. After the luteal diameter decreased for 2 consecutive days, rectal and ultrasound examinations, blood sampling, and observation of estrous signs were conducted at 6-h intervals. Most of the estrous signs became obvious with the increase in estradiol-17β (E₂) and became most remarkable 24 to 30 hours before ovulation, at which point the E₂ peak and luteinizing hormone (LH) surge were achieved, and then weakened which progression to ovulation. The correlation between the intensity of four estrous signs (hyperemia and swelling of the intravaginal part of the uterus, opening of the external uterine orifice and viscosity of the cervical mucus) and the plasma E₂ concentration was higher than that of three estrous signs (swelling of the vulva, contraction of the uterus, diameter of uterine horn) and the plasma E₂ concentration. The relaxation of the intravaginal part of the uterus showed a unique change compared with the other estrous signs, and it became most obvious 6, 12 and 18 h before ovulation; this obviously relaxed period was consistent with the generally accepted theoretical optimal time for artificial insemination (AI), i.e., 6 to 24 h after initiation of estrus. These results suggest that observation of estrous signs by vaginoscopic examination gave useful information for detection of the optimal timing of AI in the periovulatory period in lactating dairy cows kept in a tie-stall barn.