Effect of Oestrous Synchronization with Estradiol 17β and Progesterone on Follicular Wave Dynamics in Dairy Heifers

An experiment was designed to evaluate the effects of estradiol‐17β (E17β) on follicular wave dynamics and ovulatory response in Holstein heifers receiving either a progestogen ear‐implant (Crestar^®; Intervet International b.v. Boxmeer, The Netherlands) or an intravaginal progesterone‐releasing device [controlled internal drug release‐bovine device (Eazibreed, CIDR‐B^®; Bodinco BV, Alkmaar, The Netherlands)]. For comparison, another group of heifers was also synchronized using Crestar plus an injection of estradiol valerate (EV) and norgestomet as recommended by the pharmaceutical company. Twenty 20–22‐month‐old cycling Holstein heifers were allocated to one of the following treatment groups at random stages of the oestrous cycle: (I) simultaneous insertion of Crestar and intramuscular injection of 3 mg norgestomet and 5 mg EV (Crestar 9 + EV 9); (II) simultaneous insertion of Crestar and intramuscular injection of 5 mg E17β (Crestar 9 + E17β 9); (III) insertion of Crestar followed 2 days later by intramuscular injection of 5 mg E17β (Crestar 9 + E17β 7); or (IV) insertion of CIDR‐B device followed 2 days later by intramuscular injection of 5 mg E17β (CIDR 9 + E17β 7). The CIDR‐B or Crestar implants were removed after 9 days and all heifers received 500 μg Cloprostenol (Estrumate^®, Pitman‐Moore Nederland BV, Houten, The Netherlands). Ovarian ultrasonographic examinations were performed once daily during the synchronization period using a B‐mode scanner equipped with a 7.5 MHz linear‐array transrectal transducer. In addition, heifers were scanned every 12 h after implant/device withdrawal until 3 days after ovulation in order to monitor follicular activity, detect ovulation and subsequent early luteal formation. Detection of oestrus was performed every 6 h for 4 days after device/implant removal. Oestrus was observed 24–32 h before ovulation in all heifers. The mean hours interval from treatment withdrawal to ovulation was not significantly different (84.0 ± 16.5, 77.6 ± 4.1, 73.6 ± 4.1 and 64.0 ± 4.4 h for treatments I, II, III and IV, respectively; p > 0.1). However, the variance for heifers treated with EV + norgestomet was significantly larger (Levene’s Test; p < 0.01) than those treated with E17β. All E17β treatments resulted in dominant follicle suppression and a new wave emerged 4.1 days after treatment compared with 6.6 days for the EV + norgestomet treatment (p < 0.05). The time from emergence of the new ovulatory wave to ovulation was longer for the new wave that emerged after E17β treatment (9.2 ± 0.3 days) than after EV + norgestomet treatment (6.9 ± 0.4 days; p < 0.05). The results of this study suggest that the four treatments used were effective in inducing synchronous behavioural oestrus and ovulation. However, a higher degree of oestrus and ovulation synchrony was observed in heifers treated with E17β than in heifers treated with EV + norgestomet. Synchronization treatments with exogenous E17β or EV + norgestomet at the time of progestin device insertion (Crestar or CIDR‐B) or 2 days later in heifers can regulate a different emergence pattern of ovarian follicular development in randomly cyclic heifers. The E17β was effective in inducing follicular suppression and resulted in the consistent emergence of a new follicular wave.     

Conception Rates after AI in Swedish Red and White Dairy Heifers: Relationship with Progesterone Concentrations at AI

Blood samples were collected from 211 dairy heifers at the time of field insemination [artificial insemination (AI)]. Heifers were defined as either first‐service heifers (n = 91) or third to eigth‐service heifers [presumed (third AI, n = 60)] or well‐defined repeat breeders (greater than the fourth AI, n = 60). Plasma progesterone concentrations at AI were evaluated in relation to oestrous behaviour at AI and conception rates post‐AI. Conception rates after third AI were good, but conception rates decreased markedly after fourth AI and onwards. Those heifers that did not become pregnant after AI had significantly higher basal progesterone concentrations (>0.5 nmol/l) at AI, so‐called suprabasal concentrations, compared with those which conceived after AI (irrespective of the number of AI practised). Relative risk for repeat breeding was 58% after AI performed at suprabasal progesterone concentrations, while it was 42% at basal (0.5) progesterone concentrations. Results from this field study confirm results obtained in earlier controlled studies of repeat‐breeder heifers (RBH), indicating that the current definition of repeat breeding should be retained. Analysis of suprabasal progesterone concentrations could be considered as a tool for identification of RBH, provided that heat detection and AI timing are optimal. Besides considering the direct costs involved in repeat breeding, it remains to be determined whether it would be economically beneficial to identify and exclude RBH from the breeding population.     

Follicular Dynamics in Heifers during Pre-pubertal and Pubertal Period Kept under Two Levels of Dietary Energy Intake

The objective of this study was to characterize follicular dynamics in pre-pubertal, pubertal and post-pubertal periods, as well as the effect of high-energy intake on follicular development and age at puberty in heifers. Thirty-one Nelore (Bos indicus) heifers, 6 months old, were randomly assigned to receive two different diets: one of low (GI) and other of high dietary energy intake (GII). Animals were evaluated in relation to body weight gain by being weighed every 21 days. Heifers were evaluated every other day by real-time linear ultrasonography to characterize ovarian structures development from weaning to post-pubertal period. Blood samples were collected to determine plasmatic concentrations of progesterone by RIA method. The ovulation was determined when progesterone concentrations were >1 ng/mL in three consecutive samples, and by ultrasound images of corpus luteum; and oestrous behaviour in some animals. Age at puberty differed among heifers of GII (17.00 +/- 0.46 months) compared with heifers of GI (19.87 +/- 0.47 months; p < or = 0.05). Maximum size of the dominant follicles at pre-pubertal period was greater in GII heifers than in GI (10.52 +/- 0.33 and 9.76 +/- 0.15 mm, respectively; p < or = 0.05). As heifers approached first ovulation time, size of dominant follicle increased (11.75 +/- 0.37 mm for GI and 12.52 +/- 0.91 mm for GII; p < or = 0.05). Body weight at puberty was not different in both groups (302.33 +/- 27.31 kg for GI and 326.19 +/- 27.78 kg for GII heifers; p > 0.05). We conclude that animals receiving high dietary energy intake attained the puberty earlier and the development of follicles were different than in low dietary energy intake.     

青年母牛在发情周期中卵泡发育波变化规律的研究

为揭示青年母牛卵泡生长发育的动态模式,作者利用B-型超声波诊断仪,对青年母牛在发情周期中卵泡生长发育的过程进行了连续观察。结果表明,卵巢上小卵泡(1~4 mm)、中卵泡(5~7 mm)和大卵泡(≥8 mm)的数量和直径均呈动态变化。大、中、小卵泡的数量、卵泡的发育要经历征集期、选择期、优势化、成熟期和闭锁退化的过程。青年母牛在整个发情周期中,优势卵泡的平均直径为13.6 mm,成熟卵泡的平均直径为13.80 mm,一个发情周期有3~4个卵泡发育波,其中有3个卵泡发育波的为多数(71.43%),有4个的为28.57%。     

不同培养时间对绵羊卵泡颗粒细胞分泌雌二醇和孕酮的影响

以绵羊卵泡颗粒细胞为研究对象,采用体外培养细胞的方法,分别于不同时间收集细胞培养液,用放射免疫法（RIA）测定雌二醇和孕酮含量。结果表明：不同培养时间对卵泡颗粒细胞分泌雌二醇影响显著,24h、36h、48h之间差异均极显著（P＜0.001）,并随时间延长,雌二醇含量呈下降趋势;在不同时间收集的细胞培养液中检测不到孕酮。     

Effects of Breed on Follicular Dynamics and Oestradiol Secretion during the Follicular Phase in Sheep

Current study evaluates effects from breed and management background on follicular dynamics and endocrine output during the follicular phase of sheep oestrous cycle. Follicular phases were synchronized with three cloprostenol doses, 10 days apart, in three groups of 10 females of different non-prolific Spanish breeds (Manchega, Rubia del Molar and Negra de Colmenar). Development of all follicles reaching antral diameters >or=2 mm was assessed by daily transrectal ultrasonographies, whereas follicular function was evaluated by measurement of plasma oestradiol concentrations. All the ovulatory follicles were present at induced luteolysis in Manchega sheep, while a 93.7% were detected in Rubia del Molar and Negra de Colmenar ewes. The mean size of these ovulatory follicles was similar between breeds at 0 h, but their growth rates were higher in Manchega ewes, reaching a larger size at oestrous detection than in Negra de Colmenar and Rubia del Molar sheep (p < 0.05). Conversely, the oestradiol levels increased with time in Rubia del Molar and Negra de Colmenar (p < 0.05); whilst remained stable in Manchega females. However, the patterns of follicular turnover were similar between breeds. These results indicate that, though differences in follicular size and size distribution, patterns of follicular turnover in sheep are affected neither by the breed nor by the background of management and selection.     

Effect of hCG on Early Luteal Serum Progesterone Concentrations in PG600‐Treated Gilts

Gilt oestrus and ovulation responses to injection of a combination of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) (PG600) can be unpredictable, possibly reflecting inadequate circulating LH activity. The objective of this study was to determine the effect of PG600 followed by supplemental hCG on gilt ovarian responses. In experiment 1, 212 Hypor gilts (160 day of age) housed on two farms in Spain received intramuscular (i.m.) injections of PG600 (n = 47), or PG600 with an additional 200 IU hCG injected either concurrently (hCG‐0; n = 39), or at 24 h (hCG‐24; n = 41) or 48 h (hCG‐48; n = 45) after PG600. A further 40 gilts served as non‐injected controls. Ovulation responses were determined on the basis of initial blood progesterone concentrations being <1 ng/ml and achieving >5 ng / ml 10 d after the PG600 injection. The incidence of ovulating gilts having progesterone concentrations >30 ng/ml were recorded. During the study period, 10% of control gilts ovulated whereas 85–100% of hormone‐treated gilts ovulated. There were no significant differences among hormone groups for proportions of gilts ovulating. The proportions of gilts having circulating progesterone concentrations >30 ng/ml were increased (p ≤ 0.02) in all hCG treated groups compared with the PG600 group. In experiment 2, a total of 76 Hypor gilts at either 150 or 200 days of age were injected with PG600 (n = 18), 400 IU eCG followed by 200 IU hCG 24 h later (n = 20), PG600 followed by 100 IU hCG 24 h later (n = 17), or 400 IU eCG followed by 300 IU hCG 24 h later (n = 21). Blood samples were obtained 10 days later for progesterone assay. There were no effects of treatment or age on incidence of ovulation, but fewer 150‐day‐old gilts treated with PG600 or 400 IU eCG followed by 200 IU hCG had progesterone concentrations >30 ng / ml. We conclude that hCG treatment subsequent to PG600 treatment will generate a higher circulating progesterone concentration, although the effect is not evident in older, presumably peripubertal, gilts. The mechanism involved and implications for fertility remain to be determined.     

苹果酸对山羊瘤胃挥发性脂肪酸浓度动态变化影响的研究

选用4头装有永久性瘤胃瘘管的土地山羊为试验动物,按4×4拉丁方试验设计,进行了苹果酸(5 g、10 g、15 g)对山羊瘤胃内挥发性脂肪酸浓度动态变化影响的研究。结果表明,在0~12 h内,10 g和15 g添加组的pH值始终高于6.0,分别比对照组提高了0.16~0.27和0.19~0.41。10 g和15 g处理组的丙酸浓度几乎在12 h内均高于对照组。4 h时,10 g和15 g处理组的丙酸浓度分别比对照组提高了22%(P<0.05)和23%(P<0.05)。10 g和15 g处理组的丙酸比例在0~12 h内分别比对照组提高了21%~56%和22%~61%,10 g和15 g处理组的乙丙比在0~12 h内分别比对照组降低了21%~41%和21%~43%。结果表明,苹果酸降低了瘤胃液乙丙比,改变了瘤胃发酵类型。     

苹果酸对山羊瘤胃挥发性脂肪酸浓度动态变化影响的研究

选用4头装有永久性瘤胃瘘管的土地山羊为试验动物,按4×4拉丁方试验设计,进行了苹果酸(5 g、10 g、15 g)对山羊瘤胃内挥发性脂肪酸浓度动态变化影响的研究.结果表明,在0～12 h内,10 g和15 g添加组的pH值始终高于6.0,分别比对照组提高了0.16～0.27和0.19～0.41.10 g和15 g处理组的丙酸浓度几乎在12 h内均高于对照组.4 h时,10 g和15 g处理组的丙酸浓度分别比对照组提高了22%(P＜0.05)和23%(P＜0.05).10 g和15 g 处理组的丙酸比例在0～12 h内分别比对照组提高了21%～56%和22%～61%,10 g和15 g处理组的乙丙比在0～12 h内分别比对照组降低了21%～41%和21%～43%.结果表明,苹果酸降低了瘤胃液乙丙比,改变了瘤胃发酵类型.     

青年娟姗母牛在发情周期中卵泡波变化规律的研究

家畜繁殖是畜牧业生产的首要环节,而母畜生殖系统的健康是发挥其繁殖力的基础。卵巢作为生殖系统的重要器官,其生理调节功能尤为重要。在20世纪70年代后期,B型超声波影像诊断技术用于大畜直肠检查和母畜的繁育,这是动物繁殖诊断技术的新革命。为了解青年娟姗母牛在发情周期中卵巢形态和卵泡发育的动态变化,进行卵泡的计数,以有效地控制卵巢功能,调整和控制青年娟姗母牛的繁殖生理过程,充分发挥优良青年娟姗母牛的繁殖潜力和遗传性能,研究利用超声影像技术对青年娟姗母牛卵泡波进行观察,现报道如下。1材料和方法1.1试验动物春季舍饲的健康、…     

Endogenous Progesterone Concentrations Affect Progesterone Release from Intravaginal Devices Used for Oestrous Synchronization in Cattle

Intravaginal progesterone‐releasing devices are largely used both as contraceptives in humans and as a component of oestrous synchronization protocols in cattle. To reduce costs in large‐scale timed artificial insemination, the reuse of these releasing devices is common. Passive hormone diffusion, however, depends on the concentration gradient, which could affect the amount of residual progesterone present in these devices after a first use. To evaluate the effect of the presence of a corpus luteum in the release of progesterone from intravaginal devices, three synchronization protocols were designed to simulate the effects of inserting the device in the early dioestrus, late dioestrus or anoestrus. Holstein‐Zebu cross‐bred heifers were randomly allocated into one of these three treatments, and a series of blood samples was taken to evaluate the plasma progesterone concentrations. After 8 days, the intravaginal devices were removed and underwent a previously validated alcoholic extraction technique to measure the residual progesterone. Non‐used devices were used as controls. As expected, the simultaneous presence of the intravaginal device and a corpus luteum resulted in increased plasma progesterone concentrations. Conversely, the amount of residual progesterone in the devices after use was inversely proportional to the plasma progesterone concentration. These results demonstrate that the release rate of progesterone from intravaginal devices is affected by the endogenous concentration of this hormone; consequently, the strategy for reuse should account for the category and expected luteal cyclic activity of the animals undergoing synchronization protocols.     

Ovarian Follicular Dynamics of five-eighths Girolando Cows

The objective of this study was to examine the follicular dynamics of five-eighths Girolando cows by observing the number of follicular development waves, days of emergence of those waves, diameters of the dominant and largest subordinate follicles and the processes of follicular selection and dominance. Ovarian follicle dynamics were monitored for 24 oestrous cycles in 12 cows, of 4 to 10 years of age, presenting regular oestrous cycles and with body scores between 3 and 4. Ovaries were observed daily for two consecutive oestrous cycles and follicles were measured with ultrasonographic equipment. The dominant follicle was considered to be that which presented a diameter ≥ 10 mm for three consecutive days and on the day of wave emergence, when a group of follicles measuring 3–5 mm in diameter would appear. Of the 24 cycles monitored, 62.5% presented two waves of follicular development and 37.5% presented three waves. The cycles presenting two waves had an average duration of 20 days, with the emergence of the waves on days 1 and 9, whereas the cycles presenting three waves had an average duration of 22 days, with emergences on days 1, 10 and 16. For cycles with two waves, both the first and second dominant follicles reached an average size of 13.8 mm, with the first regressing on day 10 and the second ovulating around day 20. For cycles with three waves, the dominant follicles of the first and second waves reached maximum diameters of 11.8 and 12 mm, respectively, with the first regressing on day 11 and the second regressing on day 17. The third dominant follicle reached a maximum diameter of 12.4 mm on day 20, and ovulated on day 22. These results lead to the conclusion that the follicular dynamics of five-eighths Girolando cows are characterized by the presence of two to three waves of follicular growth.     

不同季节对荷斯坦青年母牛超排效果的影响

本试验对895头荷斯坦青年母牛的超排效果进行比较,结果表明,春季的超排效果最好,平均可用胚胎数最多,但与冬季相比差异不显著(P>0.05),与夏季和秋季相比分别差异极显著(P<0.01)和显著(P<0.05)。春季和冬季的囊胚比例高于夏季和秋季。该结果说明,季节对奶牛超排效果和胚胎发育均有不同程度的影响,因此,可根据不同季节母牛卵巢的反应和排卵类型对超排方案进行相应的调整。     

Follicle Dynamics and its Relation with Plasma Concentrations of Progesterone, Luteinizing Hormone and Estradiol during the Egg-Laying Cycle in Ostriches

The aims of this study were (i) to describe the changes in the volume of large ovarian follicles (diameter >3 cm) during the 48 h egg laying cycle in farmed ostriches, and (ii) to quantify factors affecting the volume of the largest measured follicle and the plasma concentrations of progesterone (P₄) and estradiol‐17β (E₂β). In eight egg‐producing birds, which all ovulated during the study period, transcutaneous ultrasound scanning and blood sampling was performed at 3 h intervals. The average volume of the total number of visualized large follicles (V_total), the largest measured follicle (V_F1), the second largest follicle (V_F2) and of all follicles smaller than F2 (V_F3–Fn) were each higher before than after oviposition. V_total, V_F2 and V_F3–Fn nearly doubled in the 24‐h period before oviposition, while V_F1 remained at an equal, rather high level until oviposition. Immediately after oviposition V_total, as well as the volume of the other follicle categories, decreased within 6 h, i.e. around the moment of ovulation. By performing statistical analysis on the basis of linear mixed‐effects modelling, we quantified that: (i) V_F1 was 13.2% higher before than after oviposition and increased with 6.5% when LH increased with 1 ng/ml; (ii) P₄ levels were 93.2% higher before than after oviposition and increased with 43.1% for every 3 h closer to oviposition; when LH and E₂β levels and V_F1 increased with 1 ng/ml, 10 pg/ml and 10 ml, respectively, P₄ increased with 116.6%, 50% and 6.1%; and (iii) E₂β levels were 35.6% higher before than after oviposition, increased with 2.7% for every 3 h closer to oviposition and increased with 14.6% when LH increased with 1 ng/ml. It is concluded that during the egg‐laying cycle in ostriches: (i) follicular mass, as estimated by the volume of visualized follicles larger than 3 cm, increases before and decreases after ovulation, and (ii) follicular dynamics and its accompanying endocrine plasma hormone profiles during the egg‐laying cycle in ostriches follow a pattern similar to that in chickens.     

Follicular Dynamics, Ovulation and Conception Rates in Bitches

Real-time ultrasound imaging was used in a clinical study to estimate the number of follicles of different sizes, ovulation and conception rates, and to study follicle dynamics following oestrus-induction of bitches.
Follicles were identified during late anoestrus (between 100 and 60 days prior to the pre-ovulatory LH surge) and there appeared to be a shift in the population from small follicles (1–3 mm in diameter) to large follicles (>4 mm diameter) approximately 2 days prior to the LH surge. Corpora lutea could be reliably identified although the majority were cavitated. High ovulation rates (97–100%) and pregnant rates (86–100%) were detected, and although the conception rate was approximately 70% it varied between 8 and 92%. Within the narrow range of the clinical population studied there were trends relating age to reproduction performance. Oestrus induction with a gonadotrophin regime appeared to result in large numbers of small follicles that did not ovulate, whilst when using cabergoline the number of small and large follicels and the number of copora lutea were similar to those of control cycles.     

Effects of Twice-Weekly Follicular Punctures of Ovaries With or Without the Corpus Luteum on Follicular and Luteal Dynamics

We investigated the effects of twice-weekly follicular punctures of ovaries with or without corpus luteum (CL) on follicular and luteal dynamics. A cross-over design was used, with each cow (seven Japanese Black beef cows) being assigned to one of the three groups at 2-month intervals. Follicular punctures were performed twice weekly for three consecutive weeks until day 20 (oestrus = day 0). All visible follicles (diameter >3 mm) in the ovaries bearing CL (ipsilateral group) or those in the contralateral ovaries (contralateral group) were aspirated. As a control, all visible follicles in both ovaries were aspirated (bilateral group). Follicular development, CL formation and progesterone concentrations in each cow were monitored from days 0 to 30. Follicular growth profiles in the punctured ovaries during/after puncture treatment were similar, irrespective of the presence of follicles in the unpunctured ovary and the CL in the punctured or unpunctured ovaries. After puncture, two cows (28.6%) each in the ipsilateral and bilateral groups did not exhibit behavioural oestrus until day 30, whereas all cows in the contralateral group exhibited oestrus. CL growth and increase in progesterone concentrations after the last follicular puncture in the bilateral group were delayed when compared with those in the ipsilateral group. Our results indicate that the presence of follicles in the unpunctured ovary and the CL in the punctured or unpunctured ovaries does not significantly influence follicular growth in punctured ovaries during/after puncture treatment. However, follicular puncture in ovaries bearing CL may disturb or delay oestrus occurrence after treatment.     

母水牛发情周期卵泡发育动态初步研究

运用B-型超声波仪观察了自然发情的6头河流型母水牛和6头沼泽型母水牛的卵泡发育动态,发现河流型母水牛的发情周期由2个卵泡发育波组成;沼泽型母水牛以2个卵泡发育波为主(66.7%,4/6)。河流型水牛2个卵泡波分别在发情周期的第1.3、12.2天出现,其第1波征集、选择卵泡数分别为14.8和2.5个,第2波分别为14.2和3.2个;沼泽型水牛2个卵泡波分别在发情周期的第1.1、11.0天出现,其第1波征集、选择卵泡数分别为8.0和1.0个,第2波分别为7.8和1.5个。以上数据的各波征集卵泡数和选择卵泡数中,河流型水牛和沼泽型水牛之间差异显著(P0.05)。     

褪黑素对体外培养绵羊卵泡颗粒细胞分泌雌二醇和孕酮的影响

采集绵羊卵泡颗粒细胞进行体外培养,根据试验设计加入褪黑素(MLT)和HCG,分别于不同培养时间收集细胞培养液,用放射免疫测定法(RIA)测定细胞培养液中雌二醇(17β-E2)和孕酮(P4)含量。结果表明：卵泡颗粒细胞在无血清培养体系中可体外培养,并能够分泌相应17β-E2;用MLT或MLT与HCG共同处理卵泡颗粒细胞,能促进细胞分泌17β-E2,并呈时间和剂量的依赖性,但对P4的分泌没有影响。     

褪黑素对体外培养绵羊卵泡颗粒细胞分泌雌二醇和孕酮的影响

采集绵羊卵泡颗粒细胞进行体外培养,根据试验设计加入褪黑素(MLT)和HCG,分别于不同培养时间收集细胞培养液,用放射免疫测定法(RIA)测定细胞培养液中雌二醇(17β-E2)和孕酮(P4)含量。结果表明:卵泡颗粒细胞在无血清培养体系中可体外培养,并能够分泌相应17β-E2;用MLT或MLT与HCG共同处理卵泡颗粒细胞,能促进细胞分泌17β-E2,并呈时间和剂量的依赖性,但对P4的分泌没有影响。