发情监测技术对繁殖母牛发情揭发率、受胎率及分娩率的作用研究

为探讨和分析发情监测技术对繁殖母牛发情揭发率、受胎率及分娩率的作用。选择甘肃省平凉市某大型养殖场的300头母牛作为研究对象,通过穿戴牛项圈监测牛群生理数据来判断发情情况,比较和分析该牛项圈发情监测技术和人工直接观察法对繁殖母牛发情揭发率、受胎率及分娩率的作用差异显著性。结果可知,项圈检测法鉴定的发情经产母牛和育成母牛的发情揭发率、受胎率及分娩率均显著高于人工直接观察法（P>0.05）。与人工直接观察法对比,牛项圈监测法能够显著提高繁殖母牛的发情揭发率、受胎率及分娩率,这为今后优化和改善农牧场饲养管理条件和提高牛群生产性能奠定基础,也为促进我国养殖经济效益发展和乡村振兴提供参考价值。     

母牛发情性行为与内外生殖器官的变化

母牛的发情有外部性行为和内部特征,内部特征以生殖激素、生殖实质器官变化为基础,排卵为本质的生殖生理规律。因此,牛的发情鉴定应以观察外部性行为为主,触摸卵巢为辅来进行综合判定。本文主要介绍在母牛配种中如何严格区分母牛发情与不发情或生殖病,现分四个方面叙述如下。     

母牛的发情鉴定技术

<正>在牛的繁殖工作中,发情鉴定是一个重要的技术环节。通过发情鉴定,可以判断母牛发情是否正常,以便发现问题,及时解决;可以判断母牛的发情阶段,以便确定配种时机,从而达到提高受胎率的目     

肉牛的发情特点及适宜输精时间

<正>1肉牛的发情鉴定1.1发情母牛的行为表现母牛发情时,精神不安,大声哞叫;相互舔舐、摩擦,有将颌部置于另一牛背上做一些亲昵的行为;嗅闻其他母牛的阴户;站立准备爬跨或爬跨其他母牛;接受爬跨并站立不动。在这些表现中,最确实的行为征兆为被爬跨而站立不动,这种行为的牛90%以上可能是发情。接受爬跨并站立不动的发情行为持续时间较短,成年母牛约8小时,处女母牛6~8小时,另有20%左右的母牛发情持续时间少于6小时。     

育成和经产母牛肌肉注射PGF2a同期发情对比试验

[目的] 探讨应用氯前列烯醇诱导母牛同期发情的方法。 [方法] 选择育成母牛和经产母牛,一次性肌肉注射2支(0.2mg/支),通过发情数量、时间、同期率、受配率等情况对比同期发情率的差异。 [结果] 结果表明,在牛体格、生理状况和饲养管理条件大体一致的情况下,育成牛发情比经产牛早3-5h;在发情持续时间上,育成牛比经产牛早结束2-3h,症状显著,而相对持续时间较短,受配率育成牛多于经产牛。 [结论] 用一次PG法处理繁殖母牛可获得较高的同期发情率,育成牛同期发情效果稍优于经产母牛,体况因素也是母牛发情的重要影响因素之一。     

牛的发情鉴定

在牛的繁殖工作中,发情鉴定是一个重要的技术环节.通过发情鉴定,可及时找出发情母牛,准确判断发情阶段,适时配种,提高母牛受胎率和利用率,或及早发现疾病,及时治疗,从而减少或避免损失,以提高饲养经济效益.母牛的发情鉴定,目前多采用外部观察与试情法、阴道检查法、直肠检查法.     

低剂量三合激素对母牛发情效果观察

三合激素可诱发母牛发情,提高授配率,繁殖率和养牛经济效益。随着注射剂量的不同,产生的效果也不尽相同。多数文献记载的注射量为0.005—0.013毫升/公斤体重(每头牛8—5毫升)。我县从1983年开始以0.008毫升/公斤体重剂量给母牛注射,结果不同年龄和不同生理状态的母牛同期发情率都较高,但有相当一部分母牛出现断续发情     

母牛发情率偏低原因及预防措施

今年来通过对牛冷配户走访调查发现,母牛发情率有走低的趋势.母牛不发情是母牛不孕症中最常见的一种.……     

奶牛的发情鉴定技术

正1发情鉴定的意义年产1头牛犊是提高经济效益的基础和保证。不论采用自然交配、人工授精,或胚胎移植,发情鉴定是牧场维持较好繁殖管理的重要组成部分。认真观察、检查,准确记录母牛的发情时间和配种日期对预测下一次发情或产犊日期及掌握整个牛群的发情特征和采取、改进管理都很有价值。及时发现发情牛,减少失配率,并根据发情程度确定输精适期,减少输精次数,节省人力和时间,提高受胎率有重要的     

黄牛发情规律观察

黄牛及其改良牛的配种受胎率是体现肉牛生产力的重要指标。为提高母牛的繁殖率和肉牛业的经济效益,本文对多年来通过外部观察和直肠触诊积累的母牛发情时的行为表现及生理特点进行了初步的汇总分析,结果表明:①爬跨行为是群养牛群发情的主要特征,而鸣叫不安、食欲减退是散养牛发情的主要特征;②母牛发情多在早晨6:00-11:00及下午16:00- 19:00,发情持续期平均为25-26 h;③由发情开始到排卵的持续时间平均为33．98 h;排卵高峰多集中在12:00-14:00和晚上23:00到次日凌晨3:00;④卵泡发育以直径0．8-1．2 cm居多;⑤在发情开始后24 h输精,可望有一个较高的受胎率。     

Incidence of Error in Oestrus Detection Based on Secondary Oestrus Signs in a 24-h Tie-Stalled Dairy Herd with Low Fertility

Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate.     

Role of the sensitivity of detection of oestrus in the submission rate of cows treated to resynchronise oestrus

OBJECTIVE: To determine if failure to detect oestrus in cows treated to resynchronise oestrus leads to fewer cows being inseminated than are truly in oestrus. PROCEDURE: Cows in three herds were enrolled in a controlled breeding program that involved synchronisation of oestrus for a first round of artificial insemination (AI) followed by resynchronisation for a second round of AI. Just before oestrus was expected at the second round of AI, aids for the detection of oestrus were fitted, which included pedometers, radiotelemetric transmitters (HeatWatch), tail-paint and heatmount detectors. Milk samples were collected at the second round of AI (day 33, herds A and B; day 35, herd C of the treatment program) and were used in combination with pregnancy testing to determine the number of cows that were in oestrus (milk progesterone < 2.0 ng/mL) and cows that were not in oestrus (milk progesterone > 2.0 ng/mL or pregnant at second round of AI) at the time samples were collected. RESULTS: The mean sensitivity of detection of oestrus at the resynchronised oestrus was 92.5% and did not differ significantly between herds (P = 0.19). A total of 75% (60/80) of cows that were retrospectively determined to be not pregnant at the time of the second round of AI were classified as having high (> or = 2.0 ng/mL) concentrations of progesterone in milk at that time. Pregnancy testing of cows about 35 days after AI suggested that early pregnancy loss also contributed to a reduction in submission rates at the resynchronised oestrus. CONCLUSION: Failure to submit cows for insemination at a resynchronised oestrus was mainly due to cows not being in oestrus rather than due to a failure to detect oestrus.     

Treatment of Unobserved Oestrus in a Dairy Cattle Herd with Low Oestrous Detection Rate up to 60 days Post-partum

The efficiency of treatments for unobserved oestrus and their effect on the reproductive performance of a dairy cattle herd with low oestrous detection rate till 60 days post‐partum (dpp), attributed to the declivous and slippery concrete floor were investigated. The herdsman requested advice in order to improve the mean days open of the herd, but no investments were allowed because a new unit was about to be built. Due to the low oestrus detection rate of the herd, the breeding policy was to inseminate at the first detected post‐partum oestrus. Cows were examined at 20–30 dpp to assess uterine involution, ovarian activity and prevalence of reproductive disorders and, at 60 dpp if no previous oestrus was detected. Each examination included palpation per rectum, ultrasound scanning and collection of a blood sample for plasma progesterone (P4) measurement. Cows with unobserved oestrus till 60 dpp were allocated either to a treatment group (n=139) or to a control group (n=139). Three treatments were used: (a) injection of PGF_2α (PG) upon detection of a corpus luteum (CL; n = 30), cows not observed in oestrus being re‐injected 11–12 days later. AI was at oestrus; (b) PRID (n=35) or Crestar (n=74) devices kept in situ for 12 and 9 days, respectively, were associated to an injection of PG and of equine chorionic gonadotrophin (eCG) at device removal. Cows were double‐fixed time‐inseminated at 48 and 72 h after device removal. All treated cows were examined at 48–72 h after treatment to confirm oestrus. The percentage of cows detected in oestrus up to 60 dpp remained unchanged through the trial (35 and 47% for years before intervention: 1994–95; 51 and 48% for years of intervention: 1996–97). In contrast, the oestrous detection rate was high both in treated (93%) and control (100%) cows. This possibly resulted from an improvement in the oestrous detection efficiency of the herd's personnel and from examination of cows at 48–72 h after treatment. Treated and control cows had identical conception rate (CR; 36 and 37%, respectively) and reproductive performance. However, the mean days open of the herd in 1996 was significantly improved in comparison with previous years (mean ± SEM: 134 ± 6, 126 ± 5, 110 ± 4 and 114 ± 5 days, for years 1994, 1995, 1996 and 1997, respectively, p < 0.05, ANOVA ). Conception rate to AI up to 40 dpp was significantly reduced, compared with the period between 60 and 100 dpp but, mean days open were significantly improved in cows inseminated up to 60 dpp, compared with thereafter (p < 0.05).     

Some Characteristics of Primary and Secondary Oestrous Signs in High-producing Dairy Cows

Shortened and weakened oestrous signs in dairy cows may cause a failure of oestrus detection and artificial insemination timing error leading to poor reproductive performance. The aims of this study were to investigate the duration of standing oestrus in high-producing dairy cows under a free stall system, to determine the duration of expression of secondary oestrous signs before and after standing oestrus (Expt 1) and to compare the duration and intensity of oestrus between cows and heifers (Expt 2). Cattle were checked for primary and secondary oestrous signs at an interval of 4 h. Heat detection aids were also used. In Expt 1, of 56 cows which were detected in oestrus, 36 cows (64.3%) showed standing oestrus and other 20 cows (36.6%) showed secondary oestrous signs only. Duration of the standing oestrus was 6.6 +/- 6.3 h on average (+/-SD), ranging between 2 and 32 h. The cows in standing oestrus showed secondary oestrous signs during a period from 9.6 +/- 8.1 h before onset of standing to 18.4 +/- 18.8 h after the end of standing oestrus. In the cows that did not show standing oestrus, expression of secondary oestrous signs were observed for 25.7 +/- 20.5 h, which was 7.5 h shorter than the average duration of oestrus in cows showing standing oestrus. In Expt 2, nine (82%) of the 11 lactating cows in oestrus showed standing, while all the 10 heifers exhibited standing oestrus. Average duration of standing oestrus was 6.4 +/- 4.3 h in cows and 6.2 +/- 3.9 h in heifers, respectively. It may be concluded that the duration of standing oestrus is substantially shortened in lactating dairy cows, and more than one-third of cows did not show standing oestrus. In cows showing standing oestrus, duration of expression of secondary oestrous signs before and after standing is not shortened. Duration of standing oestrus in heifers was as short as that in cows.     

Postpartum anestrus in dairy cattle--a review

In modern high-yielding dairy herds fertility is of major economic importance. In order to gain maximum profit, calving intervals should not exceed 365 days. The achievement of a 365-day calving interval requires an early resumption of ovarian activity, an excellent oestrus detection, and a high first-service conception rate. Especially the inability to detect oestrus and to mate the cows by 60 to 80 days after calving is a common problem among dairy farmers nowadays. In this article a review is given about the occurrence, causes, treatment and prevention of post-partum anoestrus in dairy cows.     

Validation of a new method of visual oestrus detection on the farm

Since visual observation is the most commonly used way of detecting oestrus and is supposed to be as effective as detection with technical devices, we evaluated a recently developed oestrus detection scoring system in daily dairy practice. In this scoring system nine signs of oestrus are scored with points, ranging 3 to 100. Twenty-one dairy farmers used the scoring system during a period of 3 weeks. All cows that were more than 30 days post partum and not confirmed pregnant were monitored, using the scoring system, by the herd owners. Oestrus was confirmed by measuring progesterone concentrations in milk. With the scoring system a detection rate of 47% was achieved. This was lower than expected, because in an earlier control period, the detection rate was 64%. We concluded that this new method might be too complicated to introduce to normal herd management, because in daily practice it is too demanding to watch cows twice a day for 30 minutes, especially if the cows show only vague and infrequent symptoms of oestrus. It also appeared to be too complicated to watch the herd at the most appropriate time. However, if the scoring system is included in the daily routine, meaning that farmers are trained to watch for other symptoms than standing heat only and are able to recognize their different values, it can be a valuable aid to oestrus detection.     

Effects of prostaglandin on the reproductive performance of dairy cows

A single injection of a synthetic analogue of prostaglandin F2 alpha (fenprostalene; Syntex) on the day of calving or between days 14 and 21 after calving did not affect the calving to first service interval, the number of services per conception or the conception rate of dairy cows. In a second trial, cows calved more than 45 days were injected once weekly with prostaglandin F2 alpha (dinoprost; Upjohn) or fenprostalene until served at the first detected oestrus. The calving to first service interval and the conception rate were not affected. Following injection of either prostaglandin, the spread in the pattern of onset of oestrus and the range in the proportion of cows (75 to 98 per cent) seen in oestrus within seven days were similar. This variation in the time of onset of oestrus after the administration of prostaglandin precludes limiting oestrus detection to four or five days per week, and is a major limitation to the use of prostaglandins in breeding programmes in dairy cows.     

Fertility of N'dama and Bunaji Cattle to Artificial Insemination Following Oestrus Synchronization with PRID and PGF2α in the Hot Humid Zone of Nigeria

A study was undertaken to determine the effectiveness of a progesterone-releasing intravaginal device (PRID) and prostaglandin F2 alpha (PGF2alpha) in synchronizing oestrus in N'dama and Bunaji cows and heifers and the fertility following artificial insemination at the synchronized oestrus. A total of 116 cows and heifers (58 N'dama and 58 Bunaji) were used in two separate trials. In the first trial, oestrus was synchronized using a PRID, which was inserted for 12 days; in the second trial, oestrus was synchronized by giving two injections of PGF2alpha 13 days apart. Only animals that did not respond to the first injection were given the second injection. At the end of each treatment period, the animals were observed for oestrus for 7 days and inseminated approximately 12 h following detection of oestrus. Standing to be mounted was the single criterion used to judge an animal to have been in oestrus. PGF2alpha and PRID were both effective in synchronizing oestrus in N'dama and Bunaji cows and heifers. The respective oestrus response rates, pregnancy rate and conception rates for PRID and PGF2alpha were 85.7%, 53.6% and 62.5% for PRID, and 91.7%, 68.3% and 74.6% for PGF2alpha. N'dama cattle showed significantly (p<0.05) better oestrus response rate, pregnancy rate and conception rate than Bunaji cattle following both PRID and PGF2alpha treatments. The pregnancy rate and conception rate following PGF2alpha treatment were better (p < 0.05) than for PRID, although the oestrus response rate did not differ. It is concluded that both PRID and PGF2alpha are effective in synchronizing oestrus in N'dama and Bunaji cattle in the hot humid zone of Nigeria and the fertility to artificial insemination at the synchronized oestrus was normal and acceptable. Thus, PRID and PGF2alpha can effectively be used in intensive breeding programmes for the rapid multiplication and distribution of both cattle breeds, especially the N'dama, which is a unique and beneficial animal genetic resource for the tsetse infested hot humid zone of Nigeria.     

Comparison of a camera - software system and typical farm management for detecting oestrus in dairy cattle at pasture

AIM: To compare the sensitivity, specificity, predictive values and accuracy of detection of oestrus using a novel oestrus detection strip (ODS) and a camera-software device (CSD) with typical farm management practices of visual observation and use of tail paint in dairy cattle at pasture. METHODS: Dairy cows (n = 480) in a seasonal-calving herd managed at pasture under typical commercial conditions in New Zealand were stratified by age, body condition score and days in milk, then randomly allocated to one of two groups prior to the planned start of mating (PSM). Tail paint was applied to all cows and oestrus detected by visual observation of oestrous behaviour and removal of paint, by farm staff. One group (n = 240) was fitted with ODS and also monitored for signs of oestrus using a CSD, while the Control group (n = 240) was monitored using tail paint and visual observations only. Cows detected in oestrus were artificially inseminated (AI), and pregnancy status determined using rectal palpation and ultrasonography, 51-52 days after the end of a 55-day A period. Results of pregnancy diagnosis were used to confirm the occurrence of oestrus, and the sensitivity, specificity, predictive value and accuracy of detection of oestrus compared between oestrus detection methods. RESULTS: The sensitivity and accuracy of oestrus detection in the Control group, using visual observation and tail paint, were low. Compared with the Control group, detection of oestrus using the ODS and CSD resulted in greater sensitivity (85% vs 78%; p = 0.006), specificity (99.6% vs 98.0%; p < 0.001), positive predictive value (PPV; 88% vs 51%; p < 0.001) and overall accuracy (99.0% vs 98.0%; p < 0.001). Negative predictive value (NPV) did not differ significantly between groups (99.4% vs 99.3%; p = 0.28). Pregnancy rate to first service was higher in the CSD group than in the Control group (72% vs 39%; p < 0.05). Use of the CSD significantly increased the cumulative proportion of cows pregnant to AI over the breeding period (p = 0.044). CONCLUSION AND CLINICAL RELEVANCE: The ODS and CSD was satisfactory for detection of oestrus in seasonal calving dairy herds grazing on pasture and could improve the sensitivity and accuracy of detection of oestrus in herds where these are low.     

Gene expression patterns in the ventral tegmental area relate to oestrus behaviour in high-producing dairy cows

Reduced oestrus behaviour expression or its absence (silent oestrus) results in subfertility in high-producing dairy cows. Insight into the genomic regulation of oestrus behaviour is likely to help alleviate reproduction problems. Here, gene expression was recorded in the ventral tegmental area (VTA) of high milk production dairy cows differing in the degree of showing oestrus behaviour (H - highly expressing versus L - lowly expressing), which was then analysed. Genes regulating cell morphology and adhesion or coding for immunoglobulin G (IgG) chains were differentially expressed in VTA between cows around day 0 and 12 of the oestrus cycle, but only in cows that earlier in life tended to show high levels of oestrus behaviour (H0 versus H12). The comparisons between H and L groups of cows also revealed differential expression of several genes (e.g. those of the IgG family or encoding for pro-melanin-concentrating hormone). However, any significant changes in VTA genes expression were detected in the comparison of L0 versus L12 cows. Altogether, the genes expression profile in VTA of cows highly expressing oestrus behaviour changes together with phases of the oestrus cycle, while in case of cows expressing oestrus behaviour lowly it remains stable. This supports the existence of genomic regulation by centrally expressed genes on the expression of oestrus behaviour in dairy cows.