安格斯与荷斯坦杂交牛子宫复旧期间血液激素水平的测定与分析

为分析血液激素水平对奶牛子宫复旧的影响,本研究根据子宫复旧程度将6头安格斯与荷斯坦杂交头胎奶牛分为完成子宫复旧组和子宫复旧延迟组,并采用ELISA方法测定和分析两组奶牛从产前到产后40 d内血液中前列腺素F(PGF)、孕酮(P4)、促黄体素(LH)、促卵泡素(FSH)、雌激素(E2)浓度。结果表明:两组奶牛在第10天的平均E2浓度,在第10、35天的PGF浓度存在统计学差异(p <0.01);并且第1天、第40天的FSH浓度也存在组间差异(p <0.05)。研究结果提示E2、PGF、FSH可能与子宫复旧完整性有关。本研究将为进一步探讨激素水平参与子宫复旧的作用机制提供科学依据。     

奶牛子宫复旧期间雌激素与孕酮变化规律的研究

子宫复旧是奶牛产后生殖器官恢复的一个重要时期,复旧时间的长短会直接影响产后第一次发情的时间。本试验为研究雌激素和孕酮在子宫复旧过程中的变化规律,选择了年龄、胎次相近,健康状况良好的产后奶牛15头,应用放射免疫分析法在子宫复旧期间每3d对雌激素、孕酮测定一次,前后持续10次,由试验数据可得出,雌激素、孕酮在子宫复旧早期阶段呈下降趋势,但在18d时浓度都达到了一个峰值,至末期时雌激素水平开始下降,而孕酮水平开始逐渐上升。     

日粮不同NFC/RDP水平对围产期奶牛血清中生殖泌乳相关激素的影响

旨在研究日粮不同非纤维性碳水化合物/瘤胃降解蛋白(NFC/RDP)水平对与围产期奶牛生殖和泌乳相关的血清雌二醇(E2)、孕酮(P)、催乳素(PRL)、促黄体生成素(LH)及促卵泡激素(FSH)的影响。随机选取体况良好的围产期荷斯坦奶牛48头,随机分为6组(试验Ⅰ~Ⅵ组),每组8头,于产前28 d起各组饲喂能氮水平一定,NFC/RDP水平分别为2.87(试验Ⅰ组)、3.31(试验Ⅱ组)、3.47(试验Ⅲ组)、4.04(试验Ⅳ组)、5.06(试验Ⅴ组)、5.17(试验Ⅵ组)的日粮,产后各组奶牛均饲喂相同日粮,试验至产后7 d结束。结果显示,饲喂不同NFC/RDP水平日粮后,不同观测时间的奶牛血清E2、P、PRL、LH以及FSH浓度存在不同程度的差异。其中,日粮NFC/RDP水平为4.04的试验组(试验Ⅳ组)奶牛产后第1天、第7天血清P含量极显著高于其他各试验组(P<0.01);产后第1天、第7天血清PRL浓度分别极显著、显著高于其他各试验组(P<0.01、P<0.05);产后第1天、第7天血清LH含量极显著高于其他各试验组(P<0.01);分娩前28 d、14 d,产后第1天、第7天血清FSH含量分别显著、极显著高于其他各试验组(P<0.05、P<0.01)。结果提示,日粮NFC/RDP水平与围产期奶牛血清E2、P、PRL、LH以及FSH浓度存在着较密切的关系,且当日粮NFC/RDP水平为4.04时,有助于维持奶牛能氮平衡状况、降低奶牛围产期代谢障碍性疾病发生风险。     

产后乏情奶牛血浆生化参数的变化

在某一集约化牛场通过跟踪检测发情和乏情奶牛(每组15头)产后45 d、55 d、65 d、75 d和85 d血浆中内分泌指标促黄体素(LH)、促卵泡素(FSH)、孕酮(P_4)、雌二醇(E_2)、催乳素(PRL)和代谢指标(GLU、NEFA、BHBA、BUN),结果显示,乏情奶牛产后血浆CLU浓度低于发情奶牛,而NEFA浓度却高于发情奶牛,并且差异显著;发情组奶牛血浆中LH、FSH和E_2的含量均显著高于乏情组;乏情奶牛血浆呈现低BUN浓度、低Glu浓度和高NEFA浓度的生化特征。结论是产后奶牛能量负平衡是造成奶牛产后乏情的主要原因。奶牛生殖激素分泌量不足、分泌模式紊乱及缺乏峰值是导致奶牛发情时间间隔延长及乏情的直接原因     

奶牛子宫复旧的B-超影像学研究

应用B型实时超声断层扫描仪 (B -超 ) ,对奶牛子宫复旧过程进行研究。对 38头中国荷斯坦奶牛 ,用B -超和连续检查法监测了子宫复旧过程。结果 ,经连续直肠检查法监测 ,受试牛子宫孕角、空角和子宫颈复旧的平均时间分别为 (37.4± 3.1)、(31.4± 4.9)和 (36 .8± 4.9)d;用B -超监测则为 (35 .5± 4.5 )、(30 .8± 5 .9)和 (37.5± 5 .0 )d。并且B -超监测还发现 ,分娩当天子宫肌层平均厚度为 1.6 5cm ,产后 2 3d时减少到 1.35cm ;产后第 5天在超声影像上可见子宫内膜 ,平均厚度为 0 .3cm ,第 15天为 0 .6cm ,而到产后 2 3d平均增厚到 1.0 2cm ,子宫复旧完成时 ,子宫壁平均厚度为1.0cm ;两子宫角的横切面轮廓清晰 ,大小基本相同 ,超声影像变白。研究表明B -超监测奶牛子宫复旧过程是可行的     

奶牛分娩前后血清中瘦素和神经肽Y的浓度变化规律研究

为了研究奶牛分娩前后瘦素(Leptin)和神经肽Y(Neuropeptide Y, NPY)浓度变化规律,试验选取6头第三胎次的健康荷斯坦奶牛,分别在其分娩前3天(-3天)、分娩当天(0天)、分娩后3,6,9,12,15,18,21,24,27,30天静脉采血,离心分离血清,采用牛瘦素(LEP)与牛神经肽Y(NPY)ELISA检测试剂盒测定奶牛血清中Leptin和NPY的浓度。结果表明:奶牛产后血清中Leptin浓度总趋势呈波浪式下降,在产后3天达到峰值(62.27±10.31)ng/mL,产后30天达到最低值(18.68±1.73)ng/mL,这种变化与奶牛产后能量的摄入相关;奶牛产后血清中NPY浓度在分娩当天达到峰值(886.90±133.56)pg/mL,随后呈波浪式下降,产后30天达到最低值(144.95±36.05)pg/mL,血清中NPY浓度的变化与奶牛产后能量的摄入无关。说明奶牛产后血液中Leptin浓度的变化能够反映奶牛产后能量的波动,而血液中NPY浓度的变化并不能作为奶牛产后能量代谢的指标。     

母驴产后子宫复旧的超声评定

为了探究母驴产后子宫复旧变化情况，试验选取9头产后母驴，从产驹当天到产后第33天，用B超测定子宫不同部位及卵泡的发育动力学变化。结果表明：产后母驴子宫复旧时间平均为(24.0±2.3) d(范围18～30 d),复旧过程中经直肠超声可检测到子宫收缩活动，直肠触诊可感觉到子宫直径变化。产驹后恶露约在12 d后排完。如发生子宫积脓，B超影像会显示子宫内容物有聚集性回声区域。产后卵泡排卵前子宫角内充盈液体，子宫明显水肿，子宫中也有更多区域显示暗色无回声区。排卵时子宫水肿明显消退，卵泡呈不规则状，变得柔软。在产后(13.5±1.2) d(范围12～15 d)第一次排卵，期间子宫复旧大约完成76%,而第二次排卵一般在产后(39.0±1.7) d(范围36～42 d)。第一次和第二次排卵之间的间隔为(23.6±0.4) d(范围23～27 d),第一卵泡周期和第二卵泡周期卵泡直径差异不显著(P>0.05)。     

健宫散对产后子宫炎奶牛生殖激素的影响

试验旨在研究中药复方健宫散对子宫炎奶牛生殖激素雌二醇(E2)、促卵泡生成素(FSH)、黄体生成素(LH)的影响。选取年龄、体况评分(BCS)和胎次相近的18头奶牛,按临床症状、阴道分泌物的性状、B超检查分为患病组(患子宫炎不治疗)、正常组(未患子宫炎)和治疗组(患子宫炎治疗),每组6头。治疗组每日灌服中药健宫散400 g/头,患病组与正常组灌服生理盐水400 g/头。灌药期为一个疗程(7 d)。分别于用药前、用药中、停药后1、4、7、11、15、20 d采集血液,检测3组奶牛E2、FSH、LH指标。结果表明:中药复方健宫散治疗后E2、FSH、LH都显著上升,E2出现2个峰值,在停药后1 d达到最高峰,停药后7 d达到第2个高峰;FSH在停药后4 d达到高峰;LH在用药中达到高峰。其中E2、FSH、LH的峰值显著高于正常组、患病组,而LH的峰值比正常组、患病组峰值提前。本试验条件下,中药复方健宫散可以促进性激素分泌,调节性激素代谢,从而达到预防和治疗子宫炎效果。     

奶牛子宫复旧的研究方法

子宫复旧是指母畜分娩后其子宫恢复到未孕时的状态和功能的生理过程。奶牛子宫复旧的速度及程度是决定奶牛产后繁殖力高低的主要因素。奶牛产后首次发情、排卵时间的早晚及胚泡能否附植都与子宫复旧状况有非常密切的关系，即影响产后发情、排卵及第二次妊娠，所以子宫复旧...     

烟酸胆碱和纤维素酶提高围产期脂肪肝奶牛繁殖力的研究

给产后5天内诊断为脂肪肝的9头患牛投服烟酸、胆碱和纤维素酶，同时采血测定血浆内孕酮（P4）含量，并监测受试牛产后繁殖力指标：子宫复旧时间、产后首次排卵时间、首次发情时间、分娩至受孕的间隔时间。试验结果，试验组奶牛血浆P4值在产后20天内与对照组奶牛无明显差异，20天后试验组明显高于对照组，而对照组在产后20～30天与产后15～20天相比无明显差异；子宫复旧时间和产后首次排卵时间，试验组分别比对照组平均早4．0天和4．8天，而产后首次发情时间和分娩至受孕的间隔时间，试验组比对照组平均早17天和23天。     

Postpartum reproductive performance in dairy cows. I: Influence of animal, breed and parity

The purpose of this study was to evaluate the influence of animal, breed and parity on postpartum reproductive functions in dairy cows. A total of 141 cows were included in the experiment, which was carried out as part of a study on traits affecting longevity in Swedish dairy cows. The cows belonged to 4 different breed-groups and were 1st to 5th calvers. The duration of the study was 3 years and 44 cows were followed during 1 postpartum period, 49 cows during 2 consecutive periods, 43 cows during 3 periods and 5 cows during 4 periods.The cows were clinically examined, by rectal palpation, at 10-day intervals between calving and first AI, which was at first normal oestrus more than 50 days after calving. External signs of heat were checker and recorded three times daily by the herdsmen. Blood samples for progesterone assay were taken at days 10, 15 and 20 after calving and thereafter every 10th day until first AI. Samples taken at days 10, 15 and 20 were also assayed for content of 15-keto-13,14-dihydro-PGF_2α.Heat detection records, records from clinical examinations and plasma progesterone assays were chronologically compiled for each postpartum period and based on this, intervals between calving and postpartum ovulations, recorded uterine involution, 1st and subsequent oestrus and regular reproductive functions were estimated. Least-squares methods were used for the statistical evaluation of data.The results indicate a large variation within and between cows in postpartum reproductive performance. In the total material 1st ovulation occurred before recorded uterine involution and there was a close relationship between 1st ovulatory oestrus and the onset of regular reproductive functions. The interval between calving and 1st ovulation significantly influenced the length of the first cycle in the sense that a large proportion of the early ovulating cows had a short interval between 1st and 2nd postpartum ovulations. The large variations were also evident in the plasma levels of 15-keto-13,14-dihydro-PGF_2α. There was a marked decline between days 10 and 15 postpartum and most cows were close to basal levels at 20 days postpartum.The individual cow had a significant influence on intervals from calving to recorded uterine involution, 1st ovulatory oestrus, regular reproductive functions and conception. The breed influence was significant for intervals between calving and 1st ovulation and recorded uterine involution whereas the parity of the cow only influenced the interval between calving and recorded uterine involution.     

Hormonal, estrual, ovulatory and milk traits in postpartum dairy cows following multiple daily injections of oxytocin

Release of oxytocin at suckling or milking may delay onset of estrous cycles in postpartum cows. Twenty lactating Holsteins of mixed parity were given 100 mU oxytocin iv (n = 10) or 2 ml saline (control; n = 10) via jugular catheters at 0530, 0930, 1730 and 2130 daily from calving (d o) until 28 d postpartum. All cows were milked twice daily at 0130 and 1330. Blood was collected thrice weekly (Monday, Wednesday, Friday at 0530) for 12 wk and analyzed by radioimmunoassay for progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) in serum. On d 12, blood was collected every 15 min for 6 h via jugular catheters and concentrations of luteinizing hormone (LH), cortisol and PGFM were determined. Rate of involution of the reproductive tract was estimated twice weekly by palpation per rectum. Overall mean, baseline concentrations, number of pulses/6 h, and pulse duration of LH on d 12 were similar among treatment groups. However, oxytocin seemed to reduce (P less than .10) pulse amplitude of LH in multiparous cows (.4 +/- .2 vs .8 +/- .1 ng/ml), but not in primiparous cows. Concentrations of cortisol and PGFM in serum on d 12 were unaffected by treatment. The average intervals from calving to first ovulation, based on changes of progesterone in serum and the intervals to first estrus, were similar between treatment groups. Rates of involution of the cervix and uterus also were similar between treatments. Milk yield, percent protein in milk and somatic cell counts did not differ between treatment groups. However, percent fat in milk tended to be higher (P less than .10) in cows given oxytocin than in controls (3.99 +/- .22 vs 3.68 +/- .21). These data indicate that multiple daily injections of oxytocin did not affect: 1) length of anestrus and anovulation in postpartum dairy cows, 2) LH release and 3) rates of cervical and uterine involution.     

Interrelationships between ambient temperature, age at calving, postpartum reproductive events and reproductive performance in dairy cows: a path analysis.

Path analysis was used to determine the interrelationships between ambient temperature, age at calving, postpartum reproductive events and reproductive performance in dairy cows. The data used in the analysis were collected on 226 Holstein-Friesian cows calving in a commercial dairy herd during a 17 month period (May 1, 1981 to October 1, 1982). The data were obtained from a double blind study evaluating the effects of gonadotrophin releasing hormone and cloprostenol in postpartum cows. Rectal palpation to assess uterine involution and ovarian activity was performed on each cow on days 15, 24 and 28 postpartum. At the same time, blood samples were collected for subsequent progesterone assay. Data were recorded on the occurrence of reproductive diseases and events from the time of parturition until the diagnosis of pregnancy or until the cow left the herd in the case of culled cows. There was an increase in the incidence of retained placenta, in the percentage of cows with abnormal vaginal discharge in the early postpartum period as well as a delay in uterine involution during the winter months. In addition, cows calving during the winter had prolonged intervals to first estrus, first service and conception compared to cows calving during the summer. (Cows calving during the warmest months, on average, were seen in estrus 24 days sooner, received first service 42 days sooner and conceived 27 days sooner than cows calving during the coldest months of the year).(ABSTRACT TRUNCATED AT 250 WORDS)     

Postpartum gonadotropin secretion in Holstein-Friesian dairy cows differing genetically in liveweight

AIM: To determine whether there are differences in postpartum gonadotrophic activity between strains of Holstein-Friesian dairy cows genetically selected on mature liveweight that might explain differences between the strains in fertility, and the interval between calving and the resumption of ovarian follicular activity. METHODS: Mixed-age Holstein-Friesian cows fed generous allowances of ryegrass/white clover pasture, and genetically selected for heavy (H) or light (L) mature liveweight, were given 10 microg buserelin on Days 21, 28, 35 and 42 (Experiment 1a; n=8/group), or Days 7, 14, 21 and 28 (Experiment 1b; n=8/group) postpartum. The same dose of buserelin was also given to first-calved heifers from each strain (Experiment 1c; n=6/group) on Days 7, 14, 21, and 28 postpartum. Luteinising hormone (LH)concentrations were measured in serial blood samples that were taken for up to 240 min after administration of buserelin. In Experiment 2, serial blood samples were taken at 15-min intervals from H and L cows (n=7/group) over 8 h on Days 14, 21, 28 and 35 postpartum, to examine the endogenous secretion patterns of LH and follicle stimulating hormone (FSH).The time-course of the restoration of positive feedback between oestradiol and LH was examined by giving 1 mg oestradiol benzoate(ODB) 48 h after administration of 500 microg cloprostenol to mixed-age cows from each strain on Days 7 and 21 (n=8/group), or 14 and 28 (n=8/group) after calving (Experiment 3). Relationships between nutrition and the restoration of positive feedback were studied by giving 0.75 mg ODB/500 kg liveweight on Day 17 or 18 after calving to pure-bred Holstein (OSH) and New Zealand Friesian (NZF) cows that were fed either pasture (n=12 OSH, 12 NZF) or a total mixed ration (TMR; n=13 OSH,12 NZF) (Experiment 4). Plasma LH and FSH concentrations were measured in samples collected for 42 h (Experiment 3) or 48 h (Experiment 4) after treatment with ODB. Milk progesterone concentrations were measured 3x weekly to define the reproductive status of animals in each experiment. Conception rates were recorded for animals in all of the experiments. RESULTS: First-service conception rates were lower (p<0.05) in H than L cows (46% vs 59%). In Experiments 1b and 1c, LH response to buserelin increased between Days 7 and 28 postpartum (both p<0.001), but did not differ between strains (p=0.77 and p=0.19, respectively). In Experiment 1a, LH responses to buserelin did not change between Days 21 and 42 postpartum, but overall mean peak concentrations were significantly(p<0.001) greater in L than H cows. In Experiment 2, anoestrous H cows had higher mean (p=0.004) and episodic (p=0.001) concentrations of LH than did L cows, but in cows that had active corpora lutea there were no such differences. There were no differences in FSH concentrations between strains. LH secretion in response to exogenous oestradiol (Experiment 3) increased between Days 7 and 28 postpartum (p<0.001), but there were no differences between strains. Responses were also similar in OSH and NZF cows on Day 17 or 18 postpartum, although there was a significant effect of ration upon the proportion of cows that exhibited an LH surge (20/24 cows on grass vs 12/25 on a TMR; p=0.005). CONCLUSION: These results confirm that H cows have poorer first-service conception rates than L cows, but do not support an hypothesis that there are major differences between these strains of Holstein-Friesian dairy cows in the rate of restoration in the hypothalamo-pituitary axis. However, in anoestrous cows, differences between strains in the endogenous release of LH maybe related to an earlier onset of oestrous cycles in H animals.     

Uterine involution in Finnish dairy cows

The effect of parity on the cervical and uterine involution was studied in 79 Finnish dairy cows on a research farm. The cows were examined clinically by rectal palpation 3 times a week during 8 weeks postpartum. The diameters of the cervix and uterine horns were estimated manually. The parous uterine horn was compared with the non-parous one. The results were separately analysed in primiparous cows (n = 18) and in those with the third calving (n = 61). A significant difference (p less than 0.001) between the parous and non-parous uterine horns was obtained until 21 days. Thereafter, involution still continued and equal diameters for the horns were not found until 5 weeks after parturition. A decline of the cervical diameter continued until 30 days after the delivery. The parity had no significant effect on the swiftness of uterine or cervical involution. However, in multiparous cows the cervical diameter remained larger than that in the primiparous animals still at 8 weeks postpartum.     

A Universal Index of Uterine Discharge Symptoms from Calving to 6 Weeks Postpartum

In this paper, a new uterine discharge index (D‐index) was created and tested. It was based on a principal component analysis (PCA) of clinical findings of classical uterine discharge symptoms and rectal temperature during the postpartum period of dairy cattle. The PCA analysis revealed how uterine discharge features relate to each other and how they cluster together possibly representing different degrees of uterine inflammation. The D‐index was the result of the multivariate PCA‐analysis, and the D‐index gives a continuous value between 0 and 10. It was demonstrated that the same scale, i.e. the D‐index, can be used without any adjustment from 1 to 6 weeks post‐calving. It is valid for any type of uterine discharge without defining the type of infection or differentiating between infection and contamination. The D‐index was tested using the uterine involution data. Uterine involution was significantly delayed in the high‐D‐index group of cows. Similarly, in the test with all cows, involution was progressively delayed and the rate of involution of the pregnant horn was slowed down with the increase of the D‐index values. It is concluded that the D‐index can be a new practical, universal, tool for improved management of dairy cows in the postpartum period under commercial conditions.     

Reduced postpartum anestrus of suckled beef cows treated with microencapsulated luteinizing hormone-releasing hormone analog.

This study evaluated the effect of microencapsulated LHRH agonist (D-Trp6-LHRH) on gonadotropin release and occurrence of estrus in early postpartum beef cows. Angus cows (n = 54) were assigned randomly to two treatment groups at d 5 postpartum. Group 1 received a single i.m. injection of D-Trp6-LHRH (LHRH-A) encapsulated in poly-DL-lactide-coglycolide, calculated to release 15 micrograms of LHRH-A per day for 30 d (n = 23). Group 2 received vehicle only (control, n = 31). Blood samples (15-min intervals for 6 h) were obtained on d 5, 10, 20, 30, and 40 postpartum for evaluation of LH and FSH concentrations (n = 12 per group). Days to first postpartum estrus were reduced by treatment with LHRH-A (Group 1, 43.7 +/- 4.2 d vs Group 2, 55.9 +/- 4.7 d; P < .05). However, days to conception were similar between groups (68.9 +/- 7.9 vs 76.7 +/- 6.7 d, respectively). On the day of treatment, cows treated with LHRH-A had higher mean concentrations of LH and FSH than did controls (8.3 +/- 1.4 vs 2.0 +/- .4 ng/mL for LH and 211.0 +/- 8.6 vs 51.2 +/- 2.7 ng/mL for FSH (P < .05). There were no differences in mean concentrations of LH or FSH between treatment groups on d 10, 20, 30, and 40 postpartum. Cows given LHRH-A had more (P < .05) LH pulses on d 10 and 30 postpartum than did controls. This study demonstrated that microencapsulated D-Trp6-LHRH reduced the postpartum anestrous interval in suckled beef cows.     

Effects of progesterone and weaning on LH and FSH responses to naloxone in postpartum beef cows

Two experiments were conducted to evaluate the effects of naloxone, an endogenous opioid receptor antagonist, on LH and FSH secretion in postpartum beef cows. In Experiment 1, 24 cows were divided into three equal groups. On day 15 postpartum, all cows were bled for 8 hr at 10 min intervals to evaluate LH secretory parameters. On day 18 postpartum, three treatments were administered: (a) saline at 0730 and 1130 hr; (b) 275 mg naloxone at 0730 and 1130 hr; (c) naloxone as in (b) above, plus this group was also treated with 50 mg progesterone (P4) twice daily from day 16 to day 19. In each treatment, jugular vein samples were collected at 10 min intervals from 0800 to 1600 hr. On day 19 the same treatments were administered at the same times, however, all cows were given 25 micrograms GnRH at 1200 hr to evaluate the LH secretory response. Naloxone increased mean LH concentration (P less than .05) and tended to increase pulse amplitude and frequency compared to controls. However, the most dramatic difference was due to P4 treatment which suppressed mean LH, pulse amplitude and frequency. Treatments had no effect on LH secretion in response to a 25 micrograms dose of GnRH. In Experiment 2, the effects of suckling on the naloxone response were examined in 16 postpartum cows. On day 21 postpartum, blood was collected at 10 min intervals for 8 hr and then calves were removed from half the cows. After 3 days of calf removal, all cows were sampled at 10 min intervals for 4 hr; then naloxone was injected after each 10 min sample at a dose rate of 200 mg/hr (33 mg per injection). Naloxone treatment and sampling continued for an additional 8 hr. Calf removal alone had very little effect on LH pulsatility. However, naloxone resulted in increased pulse frequency and mean LH compared to the control period. We conclude that LH release in the early postpartum cow is partially regulated by endogenous opioid peptides. We were unable to detect any effects on FSH secretion nor on pituitary sensitivity to exogenous GnRH.