牛的诱导发情与自然发情人工授精配种效果比较

从两年的人工授精配种记录中,分别随机抽取用三合激素,氯前列烯醇处理及自然发情配种的母牛80头追踪调查其产犊情况。结果是：三合激素处理组产犊率6．25％（5/80）;氯前列烯醇组产犊率36．25％（29／80）;自然发情组产犊率40％（32／80）,经统计分析,三合激素组明显低于氯前列烯醇和自然发情组,而氯前列烯醇组与自然发情组差异不显著（P＞0．05）。表明在牛人工授精中,采用同期发配种技术时,选用氯前列烯醇可以获得与自然发情相同的效果。     

氯前列烯醇诱导奶牛同期发情的研究

应用氯前列烯醇对３００头荷斯坦奶牛进行诱导同期发情的试验。结果表明,肌注１次氯旬烯醇０．４ｍｇ或肌注１次氯前裂烯醇０．４ｍｇ,隔１１ｄ再肌注０．４ｍｇ,其供试牛的同期发情率均以空怀牛效果最佳,育成牛次之,带犊牛最差。且处理２次的供试牛,其同期发情率均高于处理１次的供试牛,用氯前列烯醇处理２次或１次的供试牛,其受胎率均以育成牛效果最佳,空怀牛次之带和犊牛最差,且处理２次的供试牛,其受胎率均高于处理１     

肉牛产后早期PG二步法同期发情效果分析

在同一牧场随机选取产后48－80d的哺乳母牛，肌肉注射氯前列烯醇0.6mg／头，发情天计为0d，第7d对黄体合格的牛进行胚胎移植。第11d对黄体不合格的牛及未发情的牛进行第二次肌肉注射氯前列烯醇0.6mg／头，20d以后对黄体合格的发情牛再次进行胚胎移植。结果产后48-60d的牛发情率、可移植率分别比61－70d、71－80d的牛低，（P＜0.025），可移植率差异不显著（P＞0.025）；PG第一次处理发情率、可移植率分别比第二次处理高。有黄体的牛发情率、可移植率分别比无黄体的牛高，差异不显著（P＞0.025）。     

牛的诱导发情与自然爱情人工授精配种效果比较

从两年的人工授精配种记录中,分别随机抽取用三合激素,氯前列烯醇处理及自然发情配种的母牛８０头追踪调查其产情况。结果是：三合激素处理组产率６．２５％（５／８０）;氯前列烯醇组产率３６．２５％（２９／８０）,经统计分析,三合激素组明显低于氯前列烯醇和自然发情组,而氯前列烯醇组与自然发情组差异不显著（Ｐ〉０．０５）。表明在牛人工授精中,采用同期发配种技术时,选用氯前列烯醇可以获得与自然发情相同的效果。     

产后繁殖保健和同期处理方案对奶牛场主要繁殖指标和经济效益的影响分析

本研究是为了分析规模化奶牛场应用产后繁殖保健和同期方案后对繁殖指标的影响,以便发现问题采取措施提高奶牛场的经济效益。收集了南疆阿克苏地区第一师所属5团三个规模化奶牛场1.7万余头次奶牛繁殖数据,包括牛号、圈舍号、发情配种记录、孕检记录、流产记录、治疗记录等,对这些相关数据进行整理,并用SPSS软件对产犊间隔、不同配种次数怀孕牛头数、产犊到首次配种间隔时间、空怀140d以上难孕牛的分布情况、产后45d以内发情率等进行分析,比较不同年度间和不同牛场之间的差异。分析结果表明,应用产后繁殖保健和同期处理方案后的2017年比2016年多产1 287头犊牛,产犊间隔有了明显的缩短,45～100d的发情配种率提高,为奶牛场创造了可观的经济效益。该方案在南疆取得非常好的效果,值得推广应用。     

诱导产后乏情母牛发情配种试验

利用国产药物三合激素、促排三号、氯前列烯醇等外源激素对本地母牛进行产后诱导发情处理 ,并根据处理后发情情况进行人工授精。表明用促排三号结合使用氯前列烯醇的效果 (ovsynch法 )显著好于使用三合激素。结果提示用 ovsynch法比较适用于对母牛产后乏情进行诱导发情配种处理     

诱导产后乏情母牛发情配种试验

利用国产药物三合激素、促排三号、氯前列烯醇等外源激素对本地母牛进行产后诱导发情处理，并根据处理后发情情况进行人工授精。表明用促排三号结合使用氯前列烯醇的效果（ovsynch法）显著好于使用三合激素。结果提示用ovsynch法比较适用于对母牛产后乏情进行诱导发情配种处理。     

氯前列烯醇诱导奶牛同期发情试验

应用氯前列烯醇对3组84头荷斯坦奶牛进行诱导同期发情,结果表明:用氯前列烯醇诱导奶牛同期发情是成功的;用氯前列烯醇处理2次的奶牛,比用氯前列烯醇处理1次的奶牛,其同期发情率、受胎率明显提高;同时,氯前列烯醇对奶牛持久黄体也有很好的治疗作用。     

激素处理产后母牛对产犊间隔及卵巢状态的影响研究

为了确定促黄体素释放激素A2(LRH-A2)和氯前列烯醇对缩短奶牛产犊间隔的影响,选择产后适宜的激素处理时间,选用51头年产奶量在5 000 kg~6 000 kg的经产荷斯坦奶牛,根据产后的时间分为对照组、试验Ⅰ组(产后2周)、试验Ⅱ组(产后20 d~40 d)、试验Ⅲ组(产后40 d~60 d),分别用LRH-A2、氯前列烯醇或LRH-A2 氯前列烯醇进行处理。并在每组随机选择3头,用B超观测处理前后奶牛的卵巢状态变化。结果表明,奶牛产后2周用LRH-A2处理,有利于缩短产犊间隔。     

应用氯前列烯醇诱发奶牛同期发情试验

对８０头成年黑白花奶牛应用氯前列烯醇处理诱发同期发情。结果；处理后１－６ｄ内出现发情的有７６头，发情率为９５％，未出现发情的母牛于处理后的第１１ｄ重复处理１次，３ｄ内均出现发情；经人工授精后，母牛的情期受胎率为９７．５％，总受胎率为１００％；２０头对照牛同期发情率为２５％，情期受胎率为８０％，总受胎率为９０％。     

泌乳早期乳中尿素氮含量对奶牛繁殖性能的影响

为探索奶牛泌乳早期乳中尿素氮含量对产后繁殖性能的影响,本研究选取海丰奶牛场的头胎荷斯坦牛1932头,于产犊后30d内采集乳样,测定乳中尿素氮含量,并收集试验牛只产后繁殖资料,用多因素方差分析法分析乳中尿素氮对产后繁殖性能的影响。结果表明,试验牛只产犊后1个月内乳中尿素氮含量为9．22±2．78mg／dL;乳中尿素氮含量对个体情期受胎率有显著影响（P〈0．05）,而对产后首次配种天数有极显著影响（P〈0．01）,乳中尿素氮含量大于15mg／dL的奶牛产后第一次配种天数显著高于低于此数值的奶牛,且个体情期受胎率显著低于此数值低的奶牛。同时乳中尿素氮含量与个体情期受胎率呈极显著负相关（P〈0．01）。据此认为,作为反映能氮平衡的关键指标,泌乳早期乳中尿素氮含量可作为预测奶牛产后繁殖性能的指标加以利用。     

Interrelationships between postpartum events, hormonal therapy, reproductive abnormalities and reproductive performance in dairy cows: a path analysis.

Path analysis was used to determine the interrelationships between postpartum administration of gonadotrophin releasing hormone and cloprostenol and the occurrence of reproductive disease and reproductive performance in dairy cows. The data analysed were those collected on 226 Holstein-Friesian cows calving in a commercial dairy herd during a 17 month period (May 1, 1981 to October 1, 1982). Cows administered gonadotrophin releasing hormone at day 15 postpartum experienced an improved rate of uterine involution as determined by rectal palpation nine days later. Although this improved rate of uterine involution reduced the risk of pyometritis, it actually directly delayed conception. Also, gonadotrophin releasing hormone therapy directly resulted in an increased incidence of pyometritis which in turn resulted in an increase incidence of cystic ovarian disease and anestrus. The occurrence of these abnormalities resulted in increased intervals from calving to first observed estrus, first service and conception. In addition to this effect, the administration of gonadotrophin releasing hormone was also associated with increased plasma progesterone concentrations at days 24 and 28 postpartum which delayed conception. Cloprostenol therapy at day 24 postpartum resulted in a decreased plasma progesterone concentration at day 28 postpartum which was directly and indirectly associated with a decrease in the calving to conception interval. The indirect effects were mediated by a reduction in days to first estrus. Cloprostenol therapy also directly resulted in a decreased calving to first observed estrus interval for reasons not attributable to the level of progesterone at day 28.     

Lack of effects of an equine chorionic gonadotropin (eCG) administration between days 9 and 15 postpartum on reproductive performance in a Holstein dairy herd

Recently, it has been demonstrated that administration of equine chorionic gonadotropin (eCG) in the postpartum period in dairy cows can enhance follicle growth, reduce the interval from calving to first ovulation and increase plasma estradiol concentrations, and, thus, could enhance reproductive performance in a dairy herd when administered on day 6 postpartum. The aim of this study was to investigate the effects of a single dose of eCG between days 9 and 15 postpartum on parameters of reproductive performance in dairy cows. German Holstein cows (n = 1937; primiparous cows: n = 748; pluriparous cows: n = 1189) in a commercial dairy farm were randomly assigned to three experimental groups. Animals within the group eCG received a single dose of 600 IU eCG intramuscularly (i.m.) between days 9 and 15 postpartum followed by an i.m. administration of 500 μg cloprostenol after 14 days. Those of treatment group PG received cloprostenol only between days 23 and 29 postpartum. Cows of the control group remained untreated. Starting on day 49 postpartum, cows were subjected to a Presynch‐Ovsynch protocol and inseminated artificially. The impact of application time (days postpartum) of eCG on the intervals calving to first service and calving to conception was statistically not significant. Outcomes of reproductive performance (i.e. first service conception rate, proportion of pregnant cows until 100 and 150 days in milk [DIM], number of inseminations until 150 DIM, calving to first service interval and calving to conception interval) did not differ significantly between treatment group eCG and group PG compared to control group. Regarding postpartum eCG administration, significant interactions between treatment and parity, season, milk yield, and early puerperal disorders, respectively, could not be shown. In conclusion, an eCG treatment of dairy cows between days 9 and 15 postpartum to increase reproductive performance cannot be recommended under the given circumstances.     

Relationships between body weight and milk yield during the early postpartum period and bull and technician and the reproductive performance of high producing dairy cows

The aim of this study was to evaluate the effect of body weight (BW) change during the early postpartum period and BW on day 50 post partum on the subsequent expression of estrus and fertility at first insemination before day 90 post partum. The data were derived from 1036 postpartum cows reaching 90 days in milk. The following data were recorded for each animal: lactation number, daily milk production at day 50 post partum, calving date, days in milk at estrus and at AI, insemination date, insemination number, inseminating bull, AI technician and body weight at calving, at day 50 post partum and at AI. Of the 1036 cows registered, 817 (78.9%) showed first estrus before day 90 post partum and were inseminated. Using logistic regression procedures and based on the odds ratio a one unit (kg) increase in the daily milk production at day 50 post partum and a one unit (kg) decrease in the BW between calving and day 50 post partum were related to a 1.03-fold increase and a 0.97-fold decrease in the estrus expression rate before day 90 post partum, respectively. Of the 817 cows inseminated before day 90 post partum, 437 became pregnant (53.5%). A one unit increase in the BW at day 50 post partum produced a 1.003-fold increase in the early fertility rate. Pregnancy rate before day 90 was also influenced by the season at calving, bull providing semen and technician. In conclusion, the register of BW during the postpartum period may be a useful tool for evaluating the nutritional status and its relationship with the subsequent reproductive efficiency in dairy cows.     

Influence of body condition at calving and postpartum nutrition on endocrine function and reproductive performance of primiparous beef cows

The influences of body condition score (BCS) at calving and postpartum nutrition on endocrine and ovarian functions, and reproductive performance, were determined by randomly allocating thin (mean BCS = 4.4 +/- 0.1) or moderate condition (mean BCS = 5.1 +/- 0.1) Angus x Hereford primiparous cows to receive one of two nutritional treatments after calving. Cows were fed to gain either 0.45 kg/d (M, n = 17) or 0.90 kg/d (H, n = 17) for the first 71 +/- 3 d postpartum. All cows were then fed the M diet until 21 d after the first estrus. A replication (yr 2; M, n = 25; H, n = 23) was also used to evaluate reproductive characteristics. Concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were quantified in plasma samples collected weekly during treatment and during 7 wk before the first estrus. Estrous behavior was detected by radiotelemetry, and luteal activity was determined based on concentrations of progesterone in plasma. All cows were bred by AI between 14 and 20 h after onset of estrus, and pregnancy was assessed at 35 to 55 d after AI by ultrasonography. Cows that calved with a BCS of 4 or 5 had similar endocrine function and reproductive performance at the first estrus. During treatment, H cows gained BW and increased BCS (P < 0.01), and had greater (P < 0.05) concentrations of IGF-I, leptin, insulin, glucose, and thyroxine in plasma than M cows. However, during the 7 wk before the first estrus, plasma concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were not affected by time. Cows previously on the H treatment had a shorter (P < 0.01) interval to first postpartum estrus and ovulation, and a larger dominant follicle (P < 0.01) at first estrus, than M cows, but duration of estrus and the number of mounts received were not influenced by nutrient intake. Pregnancy rate at the first estrus was greater (P < 0.03) for H (76%, n = 38) than for M (58%, n = 33) cows. Increased nutrient intake after calving stimulated secretion of anabolic hormones, promoted fat deposition, shortened the postpartum interval to estrus, and increased pregnancy rate at the first estrus. Concentrations of IGF-I and leptin in plasma were constant during 7 wk before the first estrus, indicating that acute changes in these hormones are not associated with the resumption of ovarian function in primiparous beef cows.     

Effects of supplemental protein type on productivity of primiparous beef cows

Effects of supplemental degradable (DIP) and undegradable (UIP) intake protein on forage intake, BW change, body condition score (BCS), postpartum interval to first estrus, conception rate, milk production and composition, serum metabolites and metabolic hormones, and calf gain were determined using 36 primiparous Gelbvieh x Angus rotationally crossed beef cows. On d 3 postpartum, cows (average initial BW = 495 +/- 10 kg and BCS = 5.5 +/- 0.1) were randomly assigned to one of three dietary supplements (12 cows/treatment). Date of parturition was evenly distributed across treatment (average span of calving date among treatments = 2.4 +/- 2.5 d). Individually fed (d 3 through 120 postpartum) dietary supplements were 0.82 kg of corn and 0.23 kg of soybean meal per day (DIP), the DIP + 0.12 kg of blood meal and 0.13 kg of corn gluten meal per day (DIP + UIP), and 0.82 kg of corn, 0.07 kg of blood meal, and 0.08 kg of corn gluten meal per day in an isonitrogenous replacement of soybean meal (UIP IsoN). Cows had ad libitum access to native grass hay (8.5% CP) and trace-mineralized salt. Total OM intake was greater (P = 0.06) for DIP + UIP than UIP IsoN cows. At 30 d postpartum, DIP + UIP cows produced more milk than UIP IsoN, with DIP being intermediate; however, at 60 d postpartum, DIP + UIP and DIP cows were not different, but both had greater milk production than UIP IsoN (treatment x day interaction; P = 0.08). A treatment x day interaction (P = 0.06) for BCS resulted from DIP + UIP cows having the greatest BCS at 60, 90, and 120 d d postpartum and DIP having greater BCS than UIP IsoN cows only on d 60 postpartum. Serum insulin concentrations were highest (treatment x day interaction; P = 0.09) for DIP + UIP cows at 30 d postpartum but did not differ among treatment thereafter. Serum insulin-like growth factor-binding protein (IGFBP)-2 (34 kDa) and -3 (40 and 44 kDa) were greatest (P < 0.0003) for DIP cows. Serum urea-N concentrations were greater (P < 0.01) in DIP + UIP cows than in either DIP or UIP IsoN cows. However, postpartum interval to first estrus, conception rate, and calf weaning weights were unaffected (P = 0.35, 0.42, and 0.64, respectively) by treatment. Although UIP in addition to or in replacement of DIP affected milk production and blood metabolites, the productivity of these primiparous beef cows was not altered. Thus, the type of supplemental protein does not seem to influence productivity of primiparous beef cows in production systems with conditions similar to our experimental conditions.     

Relationship between the first ovulation within three weeks postpartum and subsequent ovarian cycles and fertility in high producing dairy cows

The aim of this study was to investigate the relationship between the first ovulation within 3 weeks postpartum and subsequent ovarian cycles and fertility in high producing dairy cattle in Hokkaido, Japan. In Experiment 1, 110 cows (44 primiparous and 66 multiparous) were used to determine the effects of the first ovulation within 3 weeks postpartum on subsequent ovarian cycles. Milk samples were collected twice weekly from 7 to 100 days postpartum. The first ovulation was identified by an increase in milk progesterone (P4) to more than 1 ng/ml within 3 weeks postpartum. The numbers of cows showing ovulation and anovulation within 3 weeks postpartum were 31 (70.5%) and 13 (29.5%) in the primiparous cows and 35 (53.0%) and 31 (47.0%) in the multiparous cows, respectively. The patterns of ovarian resumption after calving were classified into two types (normal ovarian cycles and abnormal ovarian cycles) on the basis of milk P4 concentrations. Initiation of normal ovarian function in cows ovulated within 3 weeks postpartum occurred earlier than in anovulated cows regardless of the number of calvings (primiparous, 27.8 days vs. 44.4 days; multiparous, 30.6 days vs. 55.7 days; P<0.01). Out of the multiparous cows that ovulated within 3 weeks postpartum, initiation of normal ovarian function followed by a normal luteal phase was earlier than when it was followed by an abnormal luteal phase (25.5 days vs. 40.4 days; P<0.05). Milk P4 concentrations after the first ovulation were lower than those after the second ovulation in both the primiparous and multiparous cows (P<0.05). In Experiment 2, 22 multiparous cows were used to determine the effects of the first ovulation within 3 weeks postpartum on subsequent fertility. Blood samples were collected once a week from 0 to 3 weeks postpartum. The interval from parturition to first service in ovulated cows was shorter than in anovulated cows (68.4 days vs. 94.8 days; P<0.05). The conception rate by 100 days after calving tended to be higher in ovulated cows than in anovulated cows (50.0% vs. 16.7%, P=0.09). In conclusion, our data strongly suggests that ovulation within 3 weeks postpartum is a crucial phenomenon for subsequent resumption of ovarian function and conception, and thus it can be used as an index of subsequent reproductive performance.     

产犊季节对荷斯坦牛第一胎泌乳性能的影响

[目的]为了研究不同产犊季节对荷斯坦奶牛第一胎泌乳性能的影响,以便为长江中下游地区荷斯坦奶牛合理安排配种时间提供科学依据。[方法]利用海丰奶牛场有限公司2009年引进2480头澳系进口荷斯坦牛产犊季节及其第一胎泌乳性能的数据,分析不同产犊季节对第一胎泌乳天数、全泌乳期实际产奶量、305d校正奶量、305d脂肪产量和305d蛋白产量的影响。[结果]表明:不同产犊季节对第一胎泌乳天数和全泌乳期产奶量影响极显著(P0.01),显著影响305天脂肪产量(0.01P0.05),春季产犊的奶牛泌乳天数最长(358±10d),而冬季产犊的奶牛泌乳天数最短(299±18d),春季与夏季产犊奶牛的全泌乳期产奶量显著高于秋季、冬季产犊奶牛(P0.05),夏季产犊奶牛305d脂肪产量最高。[结论]综合各产犊季节样本量及相应泌乳性能,认为该场澳系进口荷斯坦牛最适宜产犊季节为夏末秋初,此时泌乳性能最好。该结果对同类地区引进澳系进口荷斯坦牛繁殖与生产管理有借鉴作用。     

Reproductive performance in dairy cows following postpartum treatment with gonadotrophin releasing hormone and/or prostaglandin: a field trial.

Three hundred and five Holstein Friesian cows were given either 250 micrograms gonadotrophin releasing hormone (GnRH) or saline on day 15 postpartum followed by 500 micrograms cloprostenol or saline on day 24 postpartum. Four treatment groups were formed using random allocation: Group I -- placebo (Day 15)/placebo (Day 24), Group II -- GnRH (Day 15)/placebo (Day 24), Group III -- placebo (Day 15)/cloprostenol (Day 24), Group IV -- GnRH (Day 15)/cloprostenol (Day 24). Double blind techniques were used during the follow-up period. Rectal palpation, to assess uterine involution and ovarian activity was performed just prior to each treatment and again at 28 days postpartum. In addition blood samples were collected at 15, 24 and 28 days postpartum for measurement of plasma progesterone. There were no significant differences among treatment groups with respect to services per conception, number of heats detected before first service and culling for infertility. Cows treated only with GnRH had an increased calving to first estrus and calving to first breeding interval, and tended to have an increased calving to conception interval. Treatment with cloprostenol significantly decreased calving to conception and calving to first observed estrus intervals. Treatment with GnRH on day 15 postpartum resulted in a significant increase in the subsequent incidence of pyometra and prebreeding anestrus. On the other hand, cloprostenol treatment on day 24 postpartum resulted in a decreased incidence of pyometra, regardless of GnRH treatment and a decreased incidence of prebreeding anestrus in GnRH treated cows compared to cows receiving only GnRH at day 15 postpartum.(ABSTRACT TRUNCATED AT 250 WORDS)     

产犊季节和胎次对测定奶牛日泌乳性能的影响

[目的]通过研究产犊季节、胎次对奶牛测定日泌乳性能的影响,以期为指导日粮配方调整、增加牛奶产量和提升原料奶质量提供科学依据。[方法]采集江苏某奶牛场2012年度408头奶牛共3012条生产性能测定记录,用线性模型分析产犊季节和胎次对测定日产奶量、乳脂率、乳蛋白率、脂蛋比、305d产奶量及体细胞评分的影响进行分析。[结果]表明：不同产犊季节对测定日产奶量和305d产奶量的影响极显著（P〈0．01）,对乳脂率、乳蛋白率、脂蛋比无显著影响;不同胎次除对乳脂率影响显著外（P〈0．05）,对其它奶牛泌乳性能及体细胞评分均影响极显著（P〈0．01）。[结论]夏、秋两季产犊奶牛的305d产奶量高;2～3胎产犊奶牛的泌乳性能较佳,随着胎次的增加,特别是5胎及以后,泌乳性能的各项指标都有不同程度的降低。