补饲与犊牛断乳对产后母牦牛发情周期恢复的影响研究

为了提高当年产犊母牦牛的发情率,我们对选定的120头怀孕母牦牛进行补饲,同时在犊牛产后3个月对犊牛进行隔离断奶,补饲试验于2010年3月初开始：100头母牦牛随机分为两组,试验组Ⅰ 50头母牦牛隔离断奶后进行同期发情和定时授精处理;Ⅱ组50头母牦牛隔离断乳.不进行同期发情处理,发情母牛进行人工授精。人工授精冻精液为荷斯坦和野牦牛冻精。配种45d后进行怀孕诊断。Ⅰ组发情39头,发情率为78%（39/50）,怀孕34头妊娠率为68%（34/50）;Ⅱ组发情31头,发情率为62%（31/50）,怀孕27头,妊娠率为54%（27/50）。相同草场放牧50头适配母牦牛作为对照。对照组母牛和犊牛不进行隔离和短期断乳;对照组发情率为12%（6/50）,妊娠率为6.32%（3/50）。试验结果表明,通过对带犊的母牦牛实施隔离断奶,能够明显提高当年产犊母牦牛的发情率和妊娠率。     

犊牛断乳对产后母牦牛发情周期恢复的影响

对150头当年产母牦牛在发情季节进行犊牛断乳,同时对166头隔年产干乳母牦牛进行对照,观察了犊牛断乳后母牦牛发情周期恢复的规律。结果表明断乳组母牦牛发情率为69.33%,发情持续期为15d;隔年产母牦牛发情率为89.94%,发情持续期为62d。     

采用犊牛短期断乳方式提高牦母牛繁殖性能的试验

对90头带犊大通母牦牛进行了犊牛短期断乳试验.试验组母牦牛在产犊后3月龄时,实行为期10d的短期断乳,断乳后母牦牛有81头发情,发情率90%,第二年产犊78头,繁殖率86.67%.对照组为带犊,但不断乳的母牦牛,试验期共发情2头,发情率2.22%,产犊2头,繁殖率2.22%.试验组母牦牛的发情率和繁殖率比对照组分别提高了87.78%和84.45%(P＜0.01)     

断乳后对母牦牛注射氯前列烯醇钠观察其发情效果

断乳后对母牦牛注射氯前列烯醇钠促发情处理,第一次药物处理后,两组母牛发情头数均为0头,第二次药物处理后,试验组母牦牛发情15头,发情率为75%。对照组母牦牛发情8头,发情率为40%。实验组母牦牛比对照组多发情7头,高46.67%,差异性极显著(P<0.01)。     

断乳后母牦牛注射氯前列烯醇钠的发情效果观察

对断乳后母牦牛注射氯前列烯醇钠促发情处理。第1次药物处理后,两组母牛发情头数均为0头,第2次药物处理后,试验组母牦牛发情15头,发情率为75%;对照组发情8头,发情率为40%,差异极显著（P〈0.01）。     

牦牛体况评分与繁殖效率关系的研究

396头适繁母牦牛和226头围产期牦牛按体况评分方法进行体况评分,并在发情季节进行了发情率的跟踪观察;对446头围产期牦牛按体况评分2.0组和2.0以下组在进行不同量补饲对比试验,旨在探讨体况基础上的营养调控繁殖研究。结果表明:发情牦牛的体况评分为4.16±0.44,未发情牦牛的体况评分为3.49±0.45,差异极显著;妊娠母牦牛产前体况评分在2.63,产后体况评分下降到0.34的母牦牛产后发情率达到45.46%,而产前体况低于2.0,产后体况下降0.5以上的母牦牛产后发情周期不能恢复;围产期牦牛体况评分低于2.0,补饲1kg/d,围产期体况高于2.0,补饲0.5kg/d,能使17%～30%的产后母牦牛当年进入发情配种状态。     

不同时间断乳对母牦牛发情影响的观察

对带犊牦牛分别在8月1日、8月27日和10月12日进行断乳,结果Ⅰ组母牛共发情104头,发情率为69.33%,Ⅱ组母牛发情54头,发情率为36.00%,Ⅰ组比Ⅱ组多发情50头,高48.01%,差异性极显著(P<0.01)。Ⅲ组母牛发情4头,发情率4%。Ⅱ组比三组Ⅲ组多发情36头,高90%,差异性极显著(P<0.01)。Ⅰ组母牦牛发情率最高,持续时间长,Ⅱ组母牦牛只有一个发情高峰,持续比较短,Ⅲ组母牦牛发情率低,持续时间也短。     

产后无发情和亚发情母牦牛激素诱导发情试验

选择怀孕母牦牛84头,在生产前后1个月进行补饲,其中40头在产后当年发情季节进行激素诱导发情试验,44头作对照;另选择60头自然生产的产后母牦牛在发情季节进行单纯的激素诱导发情试验,60头作对照.激素诱导发情方法是0 d注射氯前列烯醇0.2 mg,7 d后注射促黄体素释放激素A3 25 μg,连续3 d;在0和7 d进行直肠检查和血样采取,血样进行孕酮测定;测定处理时母牦牛卵巢状态,观察母牦牛发情配种受孕情况.结果显示,通过直肠检查和血浆孕酮测定,发现无发情状态的产后母牦牛占产后牦牛的63.33%和65%,亚发情的产后母牦牛占产后牦牛的36.67%和35%.采用氯前列烯醇和促性腺激素释放激素处理方案进行诱导发情,26.67%的产后母牦牛在处理后出现了发情;对怀孕母牦牛在围产期进行补饲,产后母牦牛在发情季节采用氯前列烯醇和促性腺激素释放激素诱导发情,有45.45%的产后母牦牛恢复了发情,而只补饲不进行激素诱导发情的母牦牛只有20%的母牦牛出现了发情;通过孕酮测定发现2组中激素诱导发情成功的母牦牛中,有68.18%和72%是处于亚发情状态的母牦牛.结果表明,氯前列烯醇和促性腺激素释放激素进行诱导发情的处理方案适合于产后亚发情状态的母牦牛.     

补饲、隔离断乳及同期发情处理对当年产犊母牦牛人工授精受胎效果的研究

通过采用补饲、隔离断奶及同期发情处理方法,考察对母牦牛发情率、人工授精受胎率及产犊率等繁殖性能的影响。研究结果表明,补饲+断乳组初产母牦牛和经产母牦牛与隔离断乳组及对照组初产母牦牛和经产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05);补饲组、隔离断乳组与对照组初产母牦牛和经产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05);断乳+同期发情组初产母牦牛与补饲+断乳+同期发情组初产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05);断乳+同期发情组经产母牦牛与补饲+断乳+同期发情组及补饲+同期发情组经产母牦牛的诱导发情率、受胎率产犊率相比,差异显著(P0.05)。研究表明,采用补饲、隔离断乳及同期发情处理相结合的综合措施,能显著提高当年产犊母牦牛的发情率、人工授精受胎率及产犊率。     

牦牛秋季短期育肥效果观察

秋季对断乳的老龄母牦牛通过放牧+补饲精料的方式进行短期育肥试验,并设母牦牛在犊牛断奶后直接出栏为对照。结果表明,试验组母牦牛通过补饲到出栏时体重体到239.61 kg,较对照组增重53.13 kg,差异极显著(P﹤0.01)。试验组牦牛平均产值为2 260.64元,对照组牦牛平均产值为1 860.44元,试验组牦牛的平均产值比对照组多400.20元,高21.51%,差异极显著(P﹤0.01)。除去饲料费和管理费,试验组总效益是6 1907.20元,对照组为55813.20元,秋季对断乳母牦牛通过短期育肥,30头牛增加效益6 094.00元。     

Effect of day of the estrous cycle at the initiation of a timed artificial insemination protocol on reproductive responses in dairy heifers

Our objectives were to identify stages of the estrous cycle at which initiation of a timed artificial insemination (Ovsynch/TAI) protocol may reduce pregnancy rates and to monitor ovarian follicle dynamics and corpus luteum development after initiation of the Ovsynch/TAI protocol at different stages of the cycle. Cycling Holstein heifers (n = 24) were injected twice with prostaglandin F2alpha to induce estrus and were scanned by ovarian ultrasonography to determine the day of ovulation (d 0). Heifers were assigned to initiate the Ovsynch/TAI protocol at d 2 (n = 5), 5 (n = 5), 10 (n = 4), 15 (n = 5), or 18 (n = 5) of the cycle. The Ovsynch/TAI was initiated with an injection of gonadotropin-releasing hormone agonist followed 7 d later with an injection of prostaglandin F2alpha. At 36 h after injection of prostaglandin F2alpha, heifers were injected with gonadotropin-releasing hormone agonist and inseminated 16 h later. Heifers were scanned daily during the Ovsynch/TAI protocol and every other day after insemination until 16 d later. Blood samples were collected daily starting at the 1st day heifers were scanned and continued until 16 d after insemination. Initiation of the Ovsynch/TAI protocol at d 15 of the estrous cycle caused heifers to ovulate prior to insemination. A shortened return to estrus (< 16 d) was caused by ovulation failure to the second gonadotropin-releasing hormone injection, by incomplete regression of the corpus luteum, and by short life-span of the induced corpus luteum. Day of the cycle in which the Ovsynch/TAI protocol is initiated affects dynamics of follicular development, plasma progesterone profiles, and occurrence of premature ovulation. Size of the pre-ovulatory follicle was associated positively with subsequent progesterone concentrations following insemination.     

哺乳牦牛同期发情/定时授精技术试验研究

本研究旨在对不同繁殖体况的母牦牛在补饲的基础上,分别从营养、隔离断奶、激素选择考察影响母牦牛繁殖率及同期发情处理效果。选用青海省环湖地区480头5～10岁繁殖体况不同的母牦牛,按照试验要求将母牦牛分成不同的试验组别,采用相同的同期发情处理方案,通过不同程度的补饲,补饲组与对照组的排卵率和妊娠率对比差异显著（P〈0.05...     

JSAR Innovative Technology Award. Development of ovulation synchronization and fixed time artificial insemination in dairy cows

Recently, reproductive management has become more difficult as a result of increased herd size. Problems with missing estrous signs and decrease in conception rate by artificial insemination (AI) performed at wrong timing have caused low AI conception rates. In 1995, ovulation synchronization and fixed-time AI (Ovsynch/TAI) was developed in the USA as a new reproductive technology, which was accepted as an useful reproductive management tool in many countries. However, no information on the use of Ovsynch/TAI was available in Japan. It was, therefore, warranted to show the ovulation rate and conception rate after Ovsynch/TAI using gonadotropin releasing hormone analogue (GnRH-A, fertirelin acetate) and prostaglandin F2alpha (PGF2alpha)-THAM, both were commercially available in this country. The conception rate after Ovsynch/TAI has been known to vary among different herds and individuals. Investigation and analysis of factors affecting the conception rate was also warranted to improve the conception rate. A series of experiments were carried out to establish Ovsynch/TAI using domestically produced GnRH-A and PGF2alpha and to study factors affecting conception rate after Ovsynch protocol. Ovsynch using 100 microg GnRH-A and 25 mg PGF2alpha were observed using ultrasonography. As a result, a high synchronization rate of ovulation at 16 to 20 h after the second GnRH injection was confirmed. The conception rate after Ovsynch/TAI was compared in 87 cows with the conception rate after AI at estrus induced by PGF2alpha (139 cows). Conception rate after Ovsynch/TAI was higher than the figure after AI at induced estrus (59.1% vs 20.9%, P<0.05). The dose of GnRH-A was also studied and a practical dose of GnRH-A was found to be 50 microg per cow. To clarify some factors affecting the conception rate after Ovsynch/TAI, 1,558 cows were investigated for the state of their ovaries, days after calving, parity, season, ovarian cyclicity postpartum and nutritional state at the day of Ovsynch. The overall conception rate after Ovsynch/TAI was 51.5%. Fifty-six cows (3.6%) showed estrus at 6 to 7 d after the first injection of GnRH-A. The conception rate after Ovsynch/TAI was low in cows that were 40 to 60 d postpartum, those in their 5th lactation or more, those bred in July to August, and those recovering ovarian cyclicity later than 56 d postpartum. The conception rate after Ovsynch/TAI was high in cows in which body condition score (BCS) was 3.75 at dry period and 3.0 at the day of Ovsynch. In conclusion, Ovsynch/TAI is an effective tool for the reproductive management of dairy cows. A steady and sufficient conception rate after Ovsynch/TAI could be expected by taking the factors affecting the conception rate into the consideration.     

不同卵巢机能状态及胎次对母牦牛同期发情效果的影响

在青海省环湖地区390头3～10岁繁殖体况不同的母牦牛中,研究了不同繁殖卵巢机能状态及胎次,母牦牛同期发情效果的影响。结果表明:初产青年母牦牛与经产母牦牛中隔年犊牛组与当年产犊牛组的排卵率及妊娠率有显著差异(P<0.05),经产母牦牛中无黄体卵泡组与有卵泡组和有黄体组排卵率及妊娠率有显著差异(P<0.05)。研究表明,年龄和胎次及卵巢的机能状态对母牦牛的同期发情处理效果有较大影响。通过生殖激素处理,能够明显改善母牦牛的生殖机能状态,从而提高母牦牛的发情及排卵效果。     

带犊牦牛同期发情与自然发情繁殖效果比较

[目的]为了对比带犊牦牛同期发情与自然发情繁殖效果的差异,作者根据实施的科研项目进行了两组试验,以便为甘南牦牛产业高质量发展提供参考资料。[方法]于繁殖季节在试验组母牦牛阴道内放置“孕激素阴道栓”并肌肉注射“氯前列稀醇”(CIDR+PG)诱发牦牛集中发情。[结果]结果表明,甘南牦牛在当年生产后,通过犊牛统一断奶,改变营养供给,产后3个月试验组和对照组母牦牛自然发情率分别为8%和19.2%。试验组母牦牛应用“放置孕激素阴道栓+肌肉注射氯前列稀醇”方法诱导发情后,总发情率达89.1%。试验组带犊母牦牛激素处理后受胎率为89.1%,对照组母牦牛自然发情率较低,自然交配后受胎率为100%。试验组和对照组母牦牛繁殖率、犊牛成活率分别为86.9%和19.2%、97.6%和100%,试验组犊牛的平均初生重、断奶重、6月龄重分别比对照组高1.51 kg、2.37 kg、3.28 kg,经差异显著性检验,试验组犊牛相关年龄段体重与对照组犊牛对应指标相比,初生体重差异显著(P<0.05),断奶重和6月龄体重差异极显著(P<0.01)。[结论]使用外源性激素诱发带犊母牦牛当年集中发情,母牦牛当年...     

牦牛人工授精生产西杂犏牛试验

2009年8月在青海省贵南县塔秀乡用Ovsynch/TAI模式处理母牦牛18头,按隔年产母牛和当年产母牛分为两组,用西门塔尔细管冻精进行人工授精,翌年5月6日开始生产,共生产犏牛3头,情期受胎率为16.67%,总受胎率为66.67%。     

甘南牦牛一年一产试验

[目的]通过改善母牦牛妊娠期营养条件,提高甘南牦牛的繁殖率.[方法]试验组母牛白天放牧,分早晚两次每天补饲颗粒饲料1 kg/头,产犊后每天挤一次奶.[结果]70％以上牦牛实现了一年一产,犊牛成活率也明显提高.[结论]通过改善母牦牛妊娠期的营养条件,减少挤奶次数,可提高甘南牦牛的繁殖率和犊牛成活率.     

Efficacy of Ovsynch Protocol with Antiprolactin Treatment for Timed Artificial Insemination During Non‐breeding Seasons in Yaks (Poephagus grunniens L.)

An attempt was undertaken to investigate the efficacy of Ovsynch protocol for timed artificial insemination (TAI) with or without Norprolac (antiprolactin) treatment during non‐breeding season (winter months) in yaks (n = 25). During non‐breeding season, plasma prolactin profile has been reported high due to cold and nutritional stress. The Norprolac dose of i.m. administration was standardized for prolactin suppression. Three different doses viz. 2.5, 5.0 and 7.5 mg were attempted and the dose of 7.5 mg Norprolac i.m. per animal was found to be suitable for suppression of prolactin levels up to 30 h. Ovsynch treatment with Norprolac induced more number of oestrous symptoms per animal (4.8 vs 2.1), higher LH peak concentration (24.01 vs 16.16 ng/ml), longer duration of LH surge (6.8 vs 5.2 h) and higher conception rate (70 vs 30%) in Ovsynch plus Norprolac treated animals compared with animals treated with Ovsynch alone. Therefore, this study clearly indicates the opportunity for practical application of the Ovsynch plus Norprolac protocol for TAI in yaks during non‐breeding seasons.