Effect of type of intravaginal progestagen treatment of estrous response and reproductive performance of ewes

A comparison was made of the relative effectiveness of sponge pessaries impregnated with 40mg flourogestone acetate (FGA) or 60mg medroxyprogesterone acetate (MAP) to induce a synchronized estrus in ewes. Ewes were treated with sponge pessaries for 14 days and 500 IU pregnant mares' serum gonadotropin was injected i.m. at the time of sponge removal. The degree and pattern of mating response of ewes were similar, irrespective of the treatment used, approximately 92% of the ewes being marked by the ram by 72h after sponge removal. No significant differences in fertility or litter size were observed between the treatment groups. Ewes treated with FGA sponges had a fertility of 53% and litter size of 2.3 after mating at the synchronized estrus. The corresponding values for ewes treated with MAP sponges were 57% and 2.1. Use of MAP sponges was associated with a 17.8% sponge loss during treatment compared with 1% sponge loss in ewes treated with FGA sponges. Such losses could compromise the use of MAP sponges by reducing their overall efficacy.     

Synchronisation of oestrus of goats treated with progestagen-impregnated intravaginal sponges and PMSG,and reproductive performance following natural mating or A.I. with frozen semen

Oestrus was synchronised in 88 goats using progestagen-impregnated intravaginal sponges (60 mg Repromap; Upjohn) left in place for 17 days, followed by intramuscular injection of PMSG (300 i.u.) at sponge withdrawal. The percentages of does that came into oestrus in 0–24, 25–48, 49–72 and 73–96 h periods were 42, 30.5, 10.5 and 6.5 (cumulative 89.5%). The time of onset of oestrus ranged from 16 to 40 h. Breeding at the synchronised oestrus using intact bucks (24–96 h) or artificial insemination with frozen-thawed semen, at fixed times of 24, 48, 72 and 96 h, resulted in 71% and 81% conceptions respectively. Intrauterine deposition of semen was possible in 31.3%, 62.5%, 87.5% and 6.3% of cases at 24, 48, 72 and 96 h respectively. Twinning percentages were 54.5% and 56% for natural mating and artificial insemination. Kidding was spread over a 14-day period with mean gestation lengths of 149 days for singletons and 147 days for twins. The results indicate that use of progestagen-impregnated sponges with PMSG is an efficient method of synchronisation of oestrus and may result in increased fertility in goats and, if used with A.I. with frozen semen, may contribute to increased breeding efficiency and rate of genetic improvement of goats in Asia.     

The influence of the corpus luteum on ovarian follicular dynamics during estrous synchronization in goats

Ovarian follicular dynamics and fertility are unaffected by the presence or absence of a corpus luteum during synchronization of estrus with progestins in goats. On day 5 of the estrous cycle (estrus= day 0), a gestagen-containing sponge was inserted in the vagina for 11 days. To remove corpora lutea, one group of goats (CL-, n=41) received 7.5 mg of luprostiol on days 7 and 8 of the estrous cycle. The second group of goats retained the CL (CL+, n=38). Growth and development of follicles > or =4 mm in diameter were measured daily from onset of estrus to 2 days after subsequent ovulation in seven goats from each group, using rectal ultrasonography. Estrus was detected by the use of a reproductively sterilized buck and estrous does were subsequently mated. The number of waves of follicular development (CL- =3.57+/-0.2 versus CL+ =3.14+/-0.14; P>0.05) did not differ between groups. The second wave of follicular development was present at the time of progesterone decline in the CL- group and neither its duration (CL- =4.8+/-0.4 versus CL+=5.6+/-0.7 days; P>0.05) nor the day of commencement of the third wave of follicular development (CL -=11.6+/-0.7 versus CL+=11.8+/-0.6; P>0.05) were altered by the concentration of endogenous progesterone. The pregnancy rate was similar between the two groups. (CL-=68.29% versus CL+=65.79%; P>0.05). Thus, in goats, ovarian follicular dynamics and fertility were not altered by the presence or absence of a corpus luteum during estrous synchronization.     

The effect of GnRH,eCG and progestin type on estrous synchronization following laparoscopic AI in ewes

The aim of the experiment was to evaluate the effects of GnRH and/or eCG and progestin type (implant versus CIDR) on the induction of estrus and pregnancy rate following laparoscopic AI (LAI) with frozen semen. In the first trial, ewes (n = 129) were treated with norgestomet implants for 14 days. At implant removal ewes received eCG (400 IU) and/or GnRH (25 μg) 36 h after removal, resulting in control, eCG, GnRH, and eCG/GnRH groups (n = 30–34/group). In trial 2, ewes (n = 36) were treated with intravaginal fluorogestone acetate sponges (FGA) or CIDR for 12 days. After withdrawal, half of the ewes from each progestin group received eCG (400 IU), resulting in sponge, sponge/eCG, CIDR and CIDR/eCG groups (n = 8–10/group). In both trials, estrous activity was assessed using a vasectomized ram from the time of progestin removal to laparoscopic AI with frozen semen 58–60 h (trial 1) or 54–56 h (trial 2) following cessation of treatment. In trial 1, GnRH decreased (P < 0.05) the percentage of ewes in estrus (GnRH, 75.8% versus control, 93.8% versus eCG/GnRH, 94.1%), however pregnancy rates were similar in all groups (control, 53.1%; eCG, 70.0%; GnRH, 51.5%; eCG/GnRH, 55.9%, respectively). In trial 2, neither the type of progestin nor eCG treatment effected the percentage of ewes in estrus (sponge, 75.0%; sponge/eCG, 100.0%; CIDR, 100.0%; CIDR/eCG, 90.0%). However, pregnancy rates following LAI were higher (P < 0.05) when ewes were treated with eCG (progestin + eCG, 73.7% versus progestin alone, 41.2%). Results demonstrate that the source of progestin does not influence the expression of estrus or the proportion of ewes pregnant following LAI. When progestin treatment protocols are used in combination with eCG, pregnancy rates can be increased. A dose of GnRH near the end of progestin treatment may decrease the estrous response, by inducing ovulation before normal expression of estrus.     

Ovulation synchronization following commercial application of ultrasound-guided follicle ablation during the estrous cycle in mares

A regimen of progesterone plus estradiol (P&E) was used as a standard for ovarian synchronization to test the efficacy and evaluate the commercial application of ultrasound-guided follicle ablation as a non-steroidal alternative for ovulation synchronization in mares. Recipient mares at a private embryo transfer facility were at unknown stages of the estrous cycle at the start of the experiment on Day 1 when they were randomly assigned to an ablation group (n=18-21 mares) or to a P&E group (n=20-21 mares). In the ablation group, mares were lightly sedated and all follicles > or = 10 mm were removed by transvaginal ultrasound-guided follicle aspiration. In the P&E group, a combination of progesterone (150 mg) plus estradiol (10mg) prepared in safflower oil was given daily (im) for 10 d. Two doses of prostaglandin F(2alpha) (PGF, 10mg/dose, im) were given 12 h apart on Day 5 in the ablation group, or a single dose on Day 10 in the P&E group. Human chorionic gonadotropin (hCG, 2500 IU/mare, im) was given at a fixed time, 6 and 10 d after PGF treatment in the ablation and P&E groups, respectively, with the expectation of a follicle > or = 30 mm at the time of treatment. In both the ablation and P&E groups, transrectal ultrasonography was done at the start of the study (Day 1) and again on the day of hCG treatment and daily thereafter to determine the presence of a CL, measure diameter of the largest follicle and detect ovulation. The mean interval from the start of the study and from PGF treatment to ovulation was shorter (P<0.0001) in the ablation group (13.7 and 9.7 d, respectively) compared to the P&E group (22.3 and 13.2 d, respectively). Following fixed-day treatment with hCG after PGF treatment, the degree of ovulation synchronization was not different (P>0.05) between the ablation and P&E groups within a 2-d (56 and 70%) or 4-d (83% and 90%) period. Although ultrasound-guided follicle ablation may not be practical in all circumstances, it excluded the conventional 10-d regimen of progesterone and estradiol and was considered an efficacious and feasible, non-steroidal alternative for ovulation synchronization in mares during the estrous cycle.     

The influence of ovarian status on response to estrus synchronization treatment in dairy goats during the breeding season

The influence of ovarian status (presence of a corpora lutea and follicles) on the times of the onset of estrus, LH peak and ovulation rate at a synchronized estrus was evaluated in 73 Alpine and Saanen cyclic goats. Does were treated for 11 d with 3 mg norgestomet implants or 45mg fluorogestone acetate (FGA) sponges. They also received 400 IU of PMSG and 50 μg of a PGF_2α analog on Day 9 of progestagen priming. Follicles (1 to 7 mm) and corpora lutea (CL) were counted by laparoscopy on Days 0 and 9 of progestagen treatment and 5 or 6 d after the synchronized estrus. Estrus was detected every 4 h from 16 to 60 h after the end of progestagen treatment using a vasectomized buck. The LH concentration was determined by radioimmunoassay (RIA) in blood samples collected every 4 h for 24 h beginning at the time of the onset of estrus. The number of follicles on Days 0 and 9 of progestagen treatment was not related to the time of the onset of estrus and occurrence of the LH peak or to ovulation rate. The number of CL on Day 9 influenced the time of occurrence of the LH peak but not the time of the onset of estrus. Thus, in does with 2 or 3 CL on Day 9, the LH peak occurred at 46.9 h after the end of progestagen treatment, and in does with 1 or 0 CL at 42.2 and 42.5 h, respectively, after treatment, suggesting that the number of CL at luteolysis is a factor in the variability of response after the synchronization of estrus.     

维生素E对免疫功能的影响

适当剂量的维生素Ｅ（ＶＥ）,能增强抗体和补体的产生以及抗体对抗原的应答反应,促进淋巴细胞的增殖、分化和细胞因子的产生,提高免疫细胞的细胞毒作用和吞噬细胞的吞噬作用。ＶＥ缺乏或过量,能抑制机体的免疫机能,降低对疾病的抵抗能力。     

The effect of method of GnRH administration and short-term calf removal on ovarian function and reproductive performance in postpartum suckled beef cows administered PGF(2)alpha for estrous synchronization

The first experiment was a 2 x 2 factorial experiment with calf removal (none or short-term) and method of GnRH administration (intramuscularly in saline or subcutaneously in gelatin capsules) as main effects. The durations of the GnRH-induced LH surges were similar among groups but the LH surges were delayed in the cows that received GnRH subcutaneously in gelatin capsules. Calf removal enhanced the GnRH-induced LH release for cows administered GnRH subcutaneously in a gelatin capsule but not for cows administered GnRH intramuscularly in saline. In the second experiment, 191 postpartum suckled beef cows were administered two injections of prostaglandin F(2)alpha(PGF(2)alpha) 11 days apart. After the second PGF(2)alpha injection, the cows were assigned to a 2 x 2 factorial experiment as in Experiment 1 plus one control group. Short-term calf removal (47 h) began 28 h after the second PGF(2)alpha injection. GnRH was administered 30 h after the time of calf removal. The number of cows that ovulated following the time of the GnRH treatment, the number that had abnormal luteal phases and the first-service pregnancy rates among treatment groups within the anestrous and cyclic cows classifications were not significantly different. However, several effects were detected and are reported.     

The effects of progesterone priming on reproductive performance of GnRH-PGF2alpha-treated anestrous goats

The objective of this experiment was to determine the effect of a 5-day progesterone priming prior to a GnRH-PGF2alpha treatment on reproductive performance of anestrous goats. Thirty-six Mountain Black goats were randomly assigned in a 2 x 2 factorial arrangement and were administered intravaginally on day -12, either with 300 mg progesterone inserts (CGPE and CGP) or with 0 mg progesterone (GPE and GP) for 5 days. On day -6, the goats were injected with 100 microg GnRH, followed 6 days later by 15 mg PGF2alpha (day 0), the time at which the goats in the CGPE and GPE groups were administered 300 IU eCG injections and those in CGP and GP groups were administered the control solution. The goats were exposed to four fertile bucks at 0 h and were checked for breeding marks at 6-h intervals for 72 h. Blood samples were collected from all goats for progesterone analysis. Progesterone concentrations increased only in CGPE and CGP during the period of device insertion but remained low in GPE and GP groups (P < 0.001). Progesterone levels at the time of GnRH injection on day -6 were basal (0.2 +/- 0.04 ng.mL-1) among the groups and began to increase starting on day -2. Day 0 progesterone concentrations differed (P < 0.05) among groups and were significantly influenced by CIDR-G (P < 0.001). A similar proportion of goats expressed estrus and intervals to detected estrus were shorter (P < 0.05) in the CGPE and GPE groups than in GP with no difference between the CGPE, CGP and GPE or between CGP and GP groups. The number of goats ovulating based upon elevated progesterone levels on day 0 was significantly greater (P = 0.002) in CGPE (9/9) and CGP (9/9) than GPE (6/9) and GP (5/9) groups and was significantly influenced by CIDR-G (P = 0.03). All pregnant goats had elevated progesterone concentration on day 0 and none of the goats with basal progesterone levels became pregnant. Pregnancy and kidding rates, twinning percentage and the number of kids born per goat exposed were greater (P < 0.05) among goats treated with progesterone and eCG. In conclusion, progesterone priming and eCG are essential for producing higher rates of pregnancy and kidding in GnRH-PGF2alpha-treated anestrous goats.     

The effect of treatment with a GnRH analogue on postpartum reproductive performance in Friesian cows

Three trials were conducted to examine the effect of GnRH injection on the reproductive performance of Friesian cows. In the first trial 100 μg gonadotrophin releasing hormone synthetic analogue (GnRH) was given at the time of A.I. to 32 cows while a control group received a saline placebo injection. Conception rate to first insemination was significantly higher in treated than control cows (81.3 v. 54.8%, P < 0.05).In the second trial, two groups of 19 cows each received either 100 μg GnRH or saline at 15 days postpartum. A total of 60 cows was used in the third trial in which GnRH was given at either 50 or 100 μg dose level on either days 7 or 15 postpartum while control cows were untreated. In both trials GnRH treatment reduced the intervals from calving to complete uterine involution, first ovulation and first detected oestrus. The effect was most pronounced when 100 μg GnRH was given on day 7 postpartum. Number of days open and number of services per conception were appreciably reduced when 100 μg GnRH was given at either 7 or 15 days postpartum with maximal effect when given 15 days after calving.     

Effect of methyl parathion formulation on estrous cycle and reproductive performance in albino rats

The animals were injected intraperitoneally with graded doses of methyl parathion at 1.5 to 3 mg/kg body weight for 15 days from the day of estrus. Results indicated that the methyl parathion treatment showed irregular estrous cycles, affect the duration of each estrous cycle, proestrus and diestrus were significantly changed in 2.5 and 3 mg treatment groups. But there was no significant change in the number and duration of each estrous cycle, duration of proestrus and diestrus in 1.5 and 2 mg methyl parathion treatment groups. However, there was a significant decrease in the duration of estrus, while there was no significant change in the duration of metestrus in all methyl parathion treatment rats when compared with those of the corresponding parameters of the control. There was no significant effect on number of live pups on day 1 and 5 except in 3 mg methyl parathion treatment group where it was significantly decreased. There was no significant change in reproductive indices like pregnancy, parturition, live birth and viability in all the methyl parathion treatment rats except the viability index in the highest dose.     

The reproductive performance of Thoroughbred mares treated with intravaginal progesterone at the start of the breeding season

The objective of this study was to investigate the effects of intravaginal progesterone on the reproductive performance of transitional Thoroughbred mares on commercial stud farms. Two hundred twenty-seven (227) non-lactating transitional Thoroughbred mares aged between 4 and 18 y (mean 9.4 ± 3.2 y) located on three stud farms in the Waikato region of New Zealand were used in the study performed during four consecutive breeding seasons (2007-10). Mares were age-matched in pairs and either treated with an intravaginal progesterone releasing device (Cue-Mare, 1.72 g progesterone, 10% w/w) for up to 10 d (Treated; n = 126) or left untreated (Control; n = 101). In both groups, 1,667 iu of hCG was given IV when an ovarian follicle ≥35 mm was detected (in conjunction with estrous behavior) and each mare was bred by natural service. Treated mares were served earlier in the breeding season (mean ± SD interval to first service was 13.9 ± 3.0 vs 26.7 ± 13.2 d for Treated and Control groups, respectively; P < 0.001). In the Treated and Control groups, 95.2 and 42.6% of mares were served within the first 21 d of the season (P < 0.001). Treated mares conceived earlier in the breeding season (mean number of days to conception 37.5 ± 14.2 vs 50.8 ± 21.3 d, P = 0.01). There was no difference between groups in the first service pregnancy rates (53.9 and 50.5% for Treated and Control mares, P = 0.89). Treatment with an intravaginal device increased the number of mares conceiving by the end of the breeding season (91.3 vs 82.3% for Treated and Control groups, P = 0.04). Therefore, this treatment protocol appeared to offer a convenient, economical and reliable method for managing transitional mares on commercial Thoroughbred stud farms.     

Effects of abnormal ovarian cycles during pre-service period postpartum on subsequent reproductive performance of high-producing Holstein cows

The primary objective of this study was to investigate the effects of abnormal ovarian cycles during the pre-service postpartum period on subsequent reproductive performance of high-producing Holstein cows. The study was conducted in a commercial dairy farm with approximately 150 lactating cows, in a subtropical region of Japan. Animals were kept in free-stall barn, and fed a total mixed ration. Cows that calved from June 2001 to July 2002 were included in the study. Milk samples were collected twice weekly from 2 to 11 weeks postpartum, and progesterone concentrations in skim milk were determined by ELISA. After a voluntary waiting period of 40 days, cows detected in estrus were bred by artificial insemination (AI). Pregnancy was confirmed by palpation per rectum 40-70 days after AI. Out of a total of 91 cases, 39 (42.9%) had normal ovarian cycles (ovulation within 45 days after calving, followed by normal ovarian cycles), 32 (35.2%) had prolonged luteal phase (i.e. luteal activity for >20 days), and 12 (13.2%) had anovulation or delayed first ovulation (i.e. first ovulation did not occur until >45 days after calving). The remaining (8.8%) had other types of abnormalities. When compared with cows with a normal ovarian cycle, prolonged luteal phase cows had a lower 100 days AI submission rate, conception rate and pregnancy rate (84.2% versus 56.3%; P<0.05, 50% versus 16.7%; P<0.05 and 42.1% versus 9.4%; P<0.01, respectively), and longer intervals to first AI and to conception ( 67+/-6 days versus 98+/-7 days and 95+/-9 days versus 136+/-11 days; P<0.01 for each). Similarly, when compared with cows with normal ovarian cycles, those with anovulation had lower 100 days conception rate and pregnancy rate (50% versus 0%; P<0.05 and 42.1% versus 0%; P<0.01, respectively), and longer intervals to first AI and to conception ( 67+/-6 days versus 93+/-12 days; P<0.05 and 95+/-9 days versus 155+/-14 days; P<0.01, respectively). Survival analysis of the data for calving to conception interval showed that cows with prolonged luteal phase or anovulation were getting pregnant at a slower rate, and took longer to get pregnant than the cows with normal resumption of ovarian cyclicity postpartum. In conclusion, abnormal ovarian cycles during the pre-service period postpartum adversely affected reproductive performance, including AI submission rate, pregnancy rate, interval to first AI, and calving to conception interval in high-producing Holstein cows.