Feline embryo transfer during the non-breeding season

To obtain normal kits by embryo treansfer (ET) during the non-breeding season, maintenance of pregnancy was carried out by administration of sustained action progesterone (P4) in queens. Embryos were recovered six days after mating from five donor queens in which ovulation was induced by administration of eCG and hCG. The number of embryos recovered ranged from 24 to 53 (mean: 37.2 +/- 6.4) per animal and most embryos were compacted morulae. The yield of embryos was 49.0-93.3% (mean: 73.8 +/- 9.6%). As for recipients, porcine pituitary gland preparation and hCG were administered to 19 queens and estrus and ovulation were induced in 18 queens (94.7%). These queens underwent intrauterine ET of five compacted morulae and 17 cats (94.4%) were impregnated. The number of implantations was 2-5 (mean: 3.7 +/- 0.3). Among these impregnated queens, 15 cats received P4 adminstration starting on day 24 of gestation and 1-5 newborns (mean: 3.4 +/- 0.3) were obtained by normal delivery or caesarean section on day 64-69 of gestation. However, two animals that were not treated with P4 underwent spontaneous abortion about the mid gestational period. Therefore, it is possible to obtain normal kits from queens in the non-breeding season by ET with maintenance of pregnancy by P4 administration.     

Induction of estrus during the non-breeding season in Egyptian Baladi goats

The induction of estrus during the non-breeding season was investigated in 100 Egyptian Baladi goats (Capra hircus). All animals assigned to treatments had low progesterone concentrations (<0.5 ng/ml) tested 2 times 10 days apart to confirm anestrous condition. Animals were assigned to three experimental groups. A group of animals received subcutaneous norgestomet ear implant for 11 days and a single i.m. injection of PGF2alpha 24 hr before implant removal (group I; n=40). Second group of animals received subcutaneous norgestomet ear implant for 11 days and a single i.m. injection of PGF2alpha 24 hr before implant removal and gonadotropin releasing hormone 24 hr after implant removal (group II; n=40). Third group of animals received no treatment (control group; n=20). The percentage of goats that showed estrous behavior during the first 72 hr after implant removal was 77.5, 85.0% and 10.0% in group I, group II and control group, respectively. The fertility rate was 57.5, 70.0% and 10.0% in group I, group II and control group, respectively. In conclusion, estrus can be induced in seasonally anestrous Egyptian Baladi goats using norgestomet and PGF2alpha and the injection of GnRH 24 hr after norgestomet implant removal synchronized ovulation in a higher percentage of goats.     

非繁殖季节太行山羊胚胎移植方案研究

对48只太行山羊(供体羊)、40只太行山羊和120只奶山羊(受体羊)进行了同期发情和超数排卵胚胎移植试验。其结果如下:(1)CIDR PMSG对太行山羊同期发情,有效发情率为75%;CIDR FSH对奶山羊同期发情,有效发情率为73%。(2)CIDR FSH LH组平均可用胚胎数分别与CIDR PMSG组和CIDR PMSG LH组之间差异达到极显著水平(P<0.01),而与CI-DR FSH组之间差异显著(P<0.05)。(3)CIDR FSH LH超排时,用CIDR FSH对奶山羊进行同期发情,受体妊娠率为56%;CIDR PMSG对太行山羊同期发情,受体妊娠率为60%水平。证明在非繁殖季节对太行山羊采用CIDR FSH LH超数排卵和以太行山羊及奶山羊为受体分别用CIDR PMSG和CIDR FSH同期发情来进行胚胎移植的技术方案是可行的。     

进口绵羊冷冻胚胎在非繁殖季节的移植试验

在非繁殖季节 5～ 7月份利用从澳大利亚进口的三个品种Dorset、Texel、Suffork绵羊冷冻胚胎对 419只东北半细毛羊进行手术法移植 ,同年 10～ 12月份共得三个品种羔羊 2 0 7只 ,受胎率达 43 2 %,产羔率达 114 3 6%。同时得出以下研究成果 :①移植双胚受体羊的受胎率 ( 5 5 1%)和产羔率 ( 196 3 %)明显高于移植单胚的受胎率 ( 4 2 16%)和产羔率 ( 92 3 1%) (P<0 0 5 ) ;②移植A级胚胎与B级胚胎受体羊的受胎率 ( 4 4 5 6%vs10 1 164 %)与产羔率 ( 4 3 85 %vs13 2 %)之间差异不显著 (P>0 0 5 )。     

Induced ovulation in cats using porcine pituitary gland preparation during the non-breeding season

An attempt was made to induce ovulation in 19 cats during the non-breeding season by the administration of a porcine pituitary gland preparation. The dosage was 2 mg for the first day and then 1 mg for each day until estrus was induced. Studies were made to determine whether fertilization and pregnancy were possible by mating at the time of induced estrus. Estrus was induced in 89.5% (17/19) of the cats, 3-8 days after the first administration. The average number of ovulations induced by mating was 7.3 +/- 1.3 (mean +/- SE) for 16 cats (excluding one cat that failed to ovulate). The uterine horn was flushed 6-8 days after mating in 9 of the 16 ovulated cats to determine the fertilization rate. An average of 3.6 ova were recovered from 8 out of the 9 cats (including one cat from which no ovum was recovered) which gave an average recovery rate of 38.6%. Expanded blastocysts were recovered from 5 cats, while from the other 3 cats, only unfertilized ova were recovered. Pregnancy was confirmed in the other 7 cats 15-20 days after mating. In two of the 7 cats implantation was observed, but abortion occurred at 24 and 27 days of pregnancy. Plasma progesterone concentrations were lower in the estrus-induced and bred cats as compared to these in the controls, with progesterone values approaching base concentrations, approximately by day 20 in 2 cats and by day 30 in 3 cats. It was concluded that estrus could be induced in cats during the non-breeding season by administration of porcine pituitary gland preparation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reproductive characteristics of stallions during the breeding and non-breeding season in a tropical region

The objective of this study was to investigate reproductive characteristics of stallions at a tropical zone in the breeding and non-breeding seasons. The following parameters were assessed: testicular volume; semen quality; and serum concentrations of LH, FSH, and testosterone; in addition to the percentages of germ cells and proportions of germ cells/Sertoli cells by testicular cytology in stallions. Semen was collected from eight adult stallions twice a week during a 12-week period in both seasons (6?weeks before and 6?weeks after the summer and winter solstices). Jugular blood samples were collected periodically for hormone analysis by radioimmunoassay during the same periods. Testicular measures and cytological samples were taken at the end of each period. Mean concentration of testosterone was significantly higher (P?=?0.04) during the breeding season and the proportion of Sertoli cells/100 germ cells in cytological smears was significantly lower during the breeding season (P?=?0.0001). Effects of season were not significant either for testicular volume or for any semen parameter (P?>?0.05). Seasonal changes in the mean concentrations of LH and FSH were not observed (P?>?0.05). There were also no significant differences in the mean percentages of germ cell types between both seasons (P?>?0.05). Lack of seasonal differences in the testicular volume and semen parameters of tropical stallions are probably due to the small variation in duration of natural light between the observed periods, slightly under 3?h.     

Treatment of male goats with equine chorionic gonadotrophin during the non-breeding season does not affect their sperm characteristics during the subsequent breeding season

Tropical Animal Health and Production - Equine chorionic gonadotrophin (eCG) is a hormone having FSH/LH effects. It can be used to enhance sperm quality in male goats (bucks) during the...     

Comparison of estrus induction and subsequent fertility with two different intravaginal devices in ewes during the non-breeding season

Two experiments were conducted to compare the effect of estrus induction by controlled internal drug release (CIDR) and intravaginal cream containing 500 mg progesterone (P cream) in ewes during the non-breeding season. In the first experiment, twenty-four ewes were randomly grouped for two treatments with the different intravaginal devices for 12 days: Group A was the CIDR group and Group B was the P cream group. Blood was collected from all treated ewes, and progesterone (P(4)), estradiol 17-beta (E(2)) and luteinizing hormone (LH) concentrations were measured by enzyme immunoassay. In the second experiment, the conception rates from natural mating, estrus-detected AI (inseminated 12 h after estrus detection), or fixed-time AI (inseminated 42 h after removal of an intravaginal device) in 127 ewes treated with CIDR or P cream were compared. In Experiment 1, the rate of estrus induction and the time of estrus onset after device removal were 91.7% and 36.3 +/- 15.7 h in Group A, and 100% and 35.0 +/- 12.6 h in Group B, respectively. There were no significant differences between the devices. The mean plasma P(4) concentration in Group B was significantly (P < 0.01) lower than Group A between day -9 and day -1 (Day 0: the day of device removal). However, no significant differences were found in the mean E(2) concentrations of the two groups after treatment. The mean time of estrus onset in ewes with an observed LH surge and the time of LH surge after treatment were 23.3 +/- 8.7 h and 30.3 +/- 5.0 h for Group A and 27.6 +/- 6.5 and 26.3 +/- 8.0 h for Group B, respectively, and there were no significant differences. However, a significant difference (P < 0.05) was found in the mean time from the time of estrus onset to LH surge between Group A (6.4 +/- 6.7 h) and Group B (-1.3 +/- 4.1 h). In Experiment 2, the conception rates for natural mating, estrus-detected AI, and fixed-time AI were 55.0, 29.4, and 25.0% for Group A and 40.7, 25.0, and 42.1% for Group B, respectively, and there were no significant differences. These results suggest that the effect of induction of estrus and ovulation and the rate of conception after treatment were comparable to CIDR even though the plasma P(4) concentration of the P cream method tended to be low during the insertion period.     

Superovulatory response and embryo quality in Katahdin ewes treated with FSH or FSH plus eCG during non-breeding season

The aim of this study was to evaluate the effect of a co-treatment of follicle-stimulating hormone (FSH) plus equine chorionic gonadotrophin (eCG) on serum insulin and insulin-like growth factor 1 (IGF-1) concentrations, superovulatory response, ovulatory rate, and number and production of embryos in Katahdin breed ewes during the non-breeding season. Twenty Katahdin ewes were synchronized with progestagens (CIDR) and assigned to two superovulation treatments (n = 10): (1): ewes treated with 200 mg ewe⁻¹ of FSH from day 5 to 8 after CIDR insertion at decreasing doses every 12 h (FSH group) and (2) ewes treated as FSH group plus 300 IU of eCG on day 5 after CIDR insertion (FSH + eCG group). Estrous behavior was monitored and direct mating was performed. On days − 7 (CIDR insertion), 0 (CIDR withdrawal), and 7 (embryo recovery), blood samples were collected to determine serum hormone concentrations. Co-treatment with eCG (FSH group) did not affect (P > 0.05) serum hormone levels. Superovulation response, ovulation rate, recovery rate, fertilization, and number of embryos were also similar (P > 0.05) between treatments. Compared with FSH group, FSH + eCG ewes had lower (P < 0.05) number of transferable embryos and higher (P < 0.05) number of oocyte and a tendency to increase the number of degenerated embryos (P = 0.07). Overall results suggest that the administration of eCG is not beneficial either to improve the ovulatory response or the amount of transferable embryos in Katahdin ewes superovulated with a protocol using progesterone and FSH at decreasing doses.

     

A comparative study of induction of estrus and ovulation by three different intravaginal devices in ewes during the non-breeding season

The aim of the present study was to compare three methods of estrus synchronization in ewes during the non-breeding season. Forty-two ewes were randomly grouped for three treatments with different intravaginal devices for 12 days: Group A) CIDR, Group B) Self-made P sponge, Group C) MAP (medroxyprogesterone acetate) cream sponge. Furthermore, all groups were divided into two treatments with (R) or without ram presence to examine the "ram effect". Blood was collected from all treated ewes, and progesterone (P(4)), estradiol 17-beta (E(2)) and luteinizing hormone (LH) concentrations were measured by enzyme-immunoassay. All ewes showed estrus behavior between Day 0 to 3 after device removal, and the mean onset times of their estrus were 23.0, 33.0 and 21.0 h for Groups AR, BR and CR, respectively. On Day 5 as examined by laparoscopy, the ovulation rates (and number of ovulated ewes) were 1.45 (11/11), 1.25 (12/14) and 1.21 (14/14) for Groups A, B and C, respectively. In Group C, the time to LH surge was significantly (P<0.05) later (32.4 h) than those in Groups A (27.0 h) and B (25.5 h). Ram presence did not affect the number of ovulated ewes, ovulation rate or time to LH surge. The ram introduction group had significantly (P<0.05) lower E(2) concentrations during the period from 0 h to 36 h than the groups without ram presence. These results suggest that the self-made P sponge or MAP cream sponge was effective as well as CIDR, and ram introduction was not necessary, for induction of estrus and ovulation during the non-breeding season.     

Comparative efficiency of oestrus synchronization in sheep with progesterone/eCG and progesterone/GnRH during breeding and non-breeding season

The present study compared the occurrence of oestrus behaviour and ovulation in response to the insertion of CIDR devices plus a classical treatment with equine chorionic gonadotrophin (eCG; single dose at CIDR removal) or alternative treatments with gonadotrophin-releasing hormone (GnRH, either in a single dose at 56 hr after CIDR removal, or in one dose at CIDR insertion and another dose at 56 hr after CIDR removal). The appearance of oestrus behaviour during reproductive season ranged between 84% and 95% and all females showing oestrus signs had subsequent ovulations. The response, during seasonal anoestrus, was similar in the group treated with eCG, but less than half of the females in the groups treated with GnRH showed oestrus signs in response to the treatment, although more than 80% of them showed resumption of ovulatory activity after the treatment. In conclusion, protocols based on GnRH administration offer similar yields to eCG-based protocols during the reproductive season but occurrence of oestrus in response to GnRH-based treatments is highly compromised during seasonal anoestrus.     

非繁殖季节羊诱导发情排卵的研究进展

处于乏情状态的绵山羊,不管是泌乳性乏情还是季节性乏情,卵巢上都无发育成熟至可以排出的卵泡,也无功能黄体存在.这显然是由于垂体促性腺激素活动低下,FSH与LH的水平低,这种情况下,如果用外源的生殖激素(神经生殖激素、促性腺激素、性腺激素)或创造人工气候环境或公羊效应等其它方法引起内源促性腺激素分泌与释放,可使卵巢恢复活动,引起卵泡发育成熟至排卵.     

Embryo transfer in subfertile mares

Four subfertile mares (at least 2 barren years) were used as donors in an embryo transfer program. The embryo recovery rate was 50%, varying between 0-100. The transfer of 9 embryos resulted in the pregnancy rate of 44%. The efficiency of embryo transfer using subfertile mares is low. In this material 20% of flushings resulted in a pregnancy.     

Reproductive response in suckling Corriedale ewes to the ram effect during the non-breeding season: Effect of postpartum condition and the use of medroxyprogesterone priming

The response to the ram effect and the use of progestagen priming was studied in postpartum suckling Corriedale ewes. Two experiments were carried out during the non-breeding season. In experiment 1, the effectiveness of the ram effect to induce fertile oestrus in postpartum ewes was determined. While no significant differences in the frequency of ewes in oestrus were found, the overall conception rate was significantly higher in ewes that were weaned at least 6 months before the study started (63.3%) than in 60–90 days postpartum ewes (45.3%, p < 0.01). In experiment 2, the influence of medroxyprogesterone acetate priming on the response to the ram effect in suckling Corriedale ewes was determined. The frequency of ewes in oestrus and conception rate between ewes that remained unprimed and 6-days-primed ewes were similar. We conclude that it is possible to induce oestrus in postpartum suckling Corriedale ewes using the ram effect during the non-breeding season and that the use of progestagen priming seems to be ineffective in improving the response of postpartum ewes to the ram effect.     

Embryo transfer and twinning in cattle

Recent developments in cattle embryo transfer are discussed, particularly those that are relevant to the commercial application of the technique. Cattle twinning for beef production could offer impressive economic advantages where nutrition is not a limiting factor and intensive management is possible. Evidence is discussed which suggests that cattle twins induced by embryo transfer may hold several advantages over naturally-occurring twins.

---

Kurzfassung Neuere Entwicklungen auf dem Gebiet des Embryotransfer beim Rind werden diskutiert. Besonderer Wert wird dabei auf Techniken gelegt, die sich für eine kommerzielle Anwendung eignen. Zwillingsgeburten beim Rind für die Fleischproduktion bietet beeindruckende ökonomische Vorteile in Beständen, wo Ernährung kein limitierender Faktor und intensives Management möglich ist. Es werden Daten diskutiert, die darauf hinweisen, daß Zwillings-kälber von Embryotransferstudien eine Reihe von Vorteilen gegenüber natürlich geborenen Zwillingen aufweisen.

---

Resume Les dévelopments récents en matière de transplantation embryonnaire chez les bovins sont discutés en particulier ceux ayant une appliavantages économiques là où la nutrition n'est pas un facteur limitant et l'élevage intensif possible. Il est clairement montré que les jumeaux obtenus par transplantation ovulaire offrent plus d'intérêt que les jumeaux spontanés.

---

Riassunto Vengono discussi i recenti sviluppi delle tecniche di transferimento degli embrioni nel bovino, soprattutto di quelli che sono importanti ai fini dell'applicazione commerciale. La produzione di gemelli per una più alta produzione carnea potrebbe offrire rilevanti vantaggi economici dove l'alimentazione non rappresenta un fattore limitante e dove è possible l'allevamento intensivo. Vengono anche discusse le prove secondo cui i parti gemellari indotti nel bovino mediante transferimento embrionale potrebbero presentare molti vantaggi rispetto ai parti gemellari naturali.

     

Effects of exogenous estradiol and progesterone on plasma concentrations of leptin in ewes in non-breeding season

Estradiol and progesterone may play a role in controlling leptin secretion by utilizing their receptors in adipocytes and the genomic mechanisms of the leptin gene. This study was conducted to evaluate the effects of exogenous sex steroids on the blood leptin concentrations in ewes in the non-breeding season. Multiparous ewes were fed to maintenance level for their live weights. Blood samples were collected at 12-h intervals from Days -3 to -1 to determine the basal leptin levels (pre-injection period). From Day 0 to Day 5 (injection period), blood sampling continued at 12-h intervals, and the ewes were injected intramuscularly at 24-h intervals with oil, 50 mg progesterone in oil, 1 mg of estradiol in oil, or both steroids in oil. Leptin was measured using a sensitive and specific radioimmunoassay based on recombinant bovine leptin. Overall, plasma concentrations of leptin were not affected by any of the steroid treatments, and there were no differences in the value of leptin between the pre-injection and injection periods among the 4 groups. Therefore, the exogenous estrogen and progesterone used in this study do not have a strong effect on the blood leptin concentrations of ewes in the non-breeding season.     

Embryo transfer in sheep under practice conditions

Embryo transfer was carried out on nine Texel donor ewes, one of them on two occasions, over two breeding seasons (1980 and 1981). The donors were prepared for superovulation on the farm by two different regimens and the recipients were also synchronised on the farm of origin. Surgery was carried out on donors and recipients at a veterinary practice and the techniques of anaesthesia, surgery and embryo transfer are described. Superovulation was variable and more than two ovulations were seen in only four of the 10 ewes. Forty-one corpora lutea were produced by the 10 ewes and 27 embryos were recovered. Twenty-one embryos were transferred to recipients and 14 lambs were produced. All the 10 donors except one produced lambs themselves. The value, economics and welfare aspects of the technique of embryo transfer under practice conditions are discussed and it is concluded that the procedure should not be carried out routinely but reserved for special circumstances.