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PubMed2004

Ultrasonographic characterization of the ovaries in non-pregnant first served sows and gilts.

This study was aimed firstly, to examine the ovaries in non-pregnant first served sows and gilts by transcutaneous ultrasonography and secondly, to evaluate the suitability for this procedure to be performed routinely on farms. Two thousand five hundred and twenty-three females on a 1250-sow unit, synchronized with Regumate (gilts only) and/or gonadotropins (sows and gilts) not detected as returned to estrus by daily boar contact prior to scanning were ultrasonographically tested for pregnancy between days 20 and 114 postinsemination (p.i.). Of 256 sows (S) and 130 gilts (G) found to be non-pregnant the ovaries were visualized in 87.1 and 80.0% of them, respectively. Ovarian findings were: corpora lutea (CL); follicles of 2-6mm (F(2-6)); peri-ovulatory ovarian structures (POS; comprising follicles of 7-8mm and corpora haemorrhagica); single cysts (SC); oligocystic ovarian degeneration (OOD) and polycystic ovarian degeneration (POD). Their incidence was: CL>F2-6>POS>POD ( P<0.05 ) in both S and G. POD and SC plus OOD were more frequently in S ( P<0.05 ). The ovarian findings were related to the intervals of regular (days 18-25 p.i. (R1), 38-46 p.i. (R2)) and irregular service returns (days 26-37 p.i. (IR1), 47-114 p.i. (IR2)). Comparison within intervals: CL tended to be more frequently with P<0.05 only at IR2 in S. Comparison among intervals (R1 to IR2): The percentage of females (1) with CL tended to increase (S and G) and (2) with F2-6 plus POS decreased significantly (S; P<0.05 ) or tendentiously (G). SC plus OOD was higher before R2, POD after IR1 (S and G; P<0.05 ). In conclusion, the results indicate a high heterogeneity of ovarian structures in non-pregnant first served sows and gilts up to day 114 after service and suggest CL as an important cause for a delayed and, rather than POD, a failed service return. The results further demonstrate that transcutaneous ultrasonography is an appropriate and recommended method for examining the ovaries on farm in female pigs with reproductive failures.

Animals↗
PubMed2000

Synchronization of lactating dairy cows with prostaglandin F2 alpha: insemination on observed oestrus versus timed artificial insemination.

The effect of two insemination policies after synchronization of oestrus on reproductive performance in two groups of cows was investigated. Oestrus was synchronized by two treatments with prostaglandin F2 alpha (PGF2 alpha) at a 14-day interval. Cows in Group 1 (n = 234) were inseminated twice on appointment 66 and 90 h after the second treatment. Cows in Group 2 (n = 222) were intensively watched for signs of oestrus after the synchronization protocol and inseminated on observed oestrus. Cows with abnormal discharge after synchronization were excluded from breeding and inseminated later during the study period. Service rate within 1 week after synchronization was higher in Group 1 than in Group 2 (89.3 versus 67.1%). Conception rates on first service did not differ between groups (33.2 versus 30.0%). Days to first service and days open were shorter in Group 1 (P < 0.05). The number of cows culled for infertility did not differ between the groups. Endometritis 14-20 days post-partum decreased the percentage of cows pregnant at the end of the study period in both groups but did not have a significant effect on conception rates and days open. It is concluded that additional inseminations required in the timed artificial insemination protocol were economically justified by the reduction in days open in comparison with insemination on observed oestrus after synchronization.

Animals↗
PubMed1997

Selected times of insemination with microencapsulated bovine spermatozoa affect pregnancy rates of synchronized heifers.

This experiment was designed to test whether spermatozoa encapsulated in an alginate poly-L-lysine matrix had an extended fertile life in vivo after insemination. Estrus was synchronized in 417 primiparous Friesian and Jersey heifers with a system based on a CIDR-B intravaginal device before the heifers were inseminated either during proestrus (24 h after device removal) or at estrus (48 h after device removal). Pregnancy rates to first inseminations did not differ between the 24 and 48 h inseminations (61 vs 60.6%) with liquid semen diluted in Caprogen (control) but differed with encapsulated semen (45.1 vs 68.6%). The difference in pregnancy rates between the 2 types of semen was more pronounced (P < 0.08) in the animals that were visually detected in estrus. The mean survival time of spermatozoa in the female reproductive tract following insemination at the 24-h insemination time was estimated to be 50 +/- 7.5 h. The increased pregnancy rate with insemination of encapsulated spermatozoa at 48 h could have been due to this process predisposing spermatozoa to capacitate soon after insemination.

Journal Article↗
PubMed2005

Short communication: Conception rates following detection of estrus and timed AI in dairy cows synchronized using GnRH and PGF2alpha.

The objective of this study was to compare conception rates of cows exhibiting spontaneous estrus and receiving artificial insemination (AI) before completion of a timed AI protocol with cows that did not display estrus spontaneously, but were inseminated after 1 of 3 GnRH-PGF2alpha protocols. Cows (n = 432) in 2 herds were administered GnRH on d -7 and were tail-chalked daily. Cows detected in estrus before d 0 were inseminated immediately. Cows not detected in estrus by d 0 were administered PGF2alpha and were tail-chalked daily until 48 h after PGF2alpha. Cows detected in estrus from d -7 to 48 h after PGF2alpha were inseminated and designated as treatment A (n = 46). Cows not detected in estrus and not inseminated by 48 h after PGF2alpha were assigned randomly to receive either GnRH 48 h after PGF2alpha and timed AI 16 h later (treatment B; n = 132), or GnRH and timed AI 64 h after PGF2alpha (treatment C; n = 127), or timed AI 64 h after PGF2alpha (treatment D; n = 127). Pregnancy was diagnosed 38 to 45 d after AI by palpation per rectum of uterine contents. Nearly 11% of all cattle exhibited spontaneous estrus and received immediate AI. Herd did not influence the percentage of cows detected in estrus and inseminated. Conception rates did not differ among treatments. Conception rates differed between herds, but no interaction of herd x treatment was detected. No differences were detected between herds for days in milk, milk production, AI service number, or parity.

Animals↗
PubMed1989

Embryo transfer in the White-tailed deer: A reproductive model for endangered deer species of the world.

A model for artificial propagation of wild, seasonal breeding deer was developed using the White-tailed deer, Odocoileus , virginianus . Preseason estrus induction following removal of vaginal pessaries containing medroxyprogesterone acetate (MPA) was successful in four of seven animals. Synchronization of estrus was achieved in seven of nine attempts when does were treated with prostaglandin F(2) alpha (PGF(2)alpha) 7 to 14 d following observed estrus. Superovulation was achieved in two of five does treated with 1000 IU of pregnant mare's serum gonadotropin (PMSG) at the time of vaginal pessary MPA withdrawal. Superovulation was achieved in two of three does treated with 1000 IU of PMSG at the time of estrus induction with PGF(2)alpha. Surgical embryo recoveries attempted on six does resulted in a 68% embryo recovery rate based on numbers of corpora lutea observed. Surgical embryo transfers from two donors to three recipient does resulted in one pregnancy maintained to full term.

Journal Article↗
PubMed1989

Effect of estradiol on secretion of luteinizing hormone during the follicular phase of the bovine estrous cycle.

Mean concentrations of luteinizing hormone (LH) increase during the follicular phase of the estrous cycle in cows. The working hypotheses in the present study were (1) that increasing concentrations of 17 beta-estradiol (E2) during the follicular phase of the estrous cycle cause an increase in mean concentration of LH by increasing amplitude of pulses of LH, and (2) that increasing E2 concentrations during this stage of the estrous cycle decrease frequency of pulses of LH in bovine females. Day of estrus was synchronized in seventeen mature cows. Treatments were initiated on Day 16 of the experimental estrous cycle (Day 0 = estrus). At Hour 0 (on Day 16), 4 cows were lutectomized. Lutectomy of these cows (EE; n = 4) allowed for endogenous secretion of E2. The remaining cows were ovariectomized at Hour 0 and were assigned to one of three E2 treatments: luteal phase E2 (LE, n = 5), increasing then decreasing E2 (DE, n = 5), and no E2 (NE, n = 3). Cows in the group that received LE were administered one E2 implant at Hour 0, which provided low circulating concentrations of E2 similar to those observed during the luteal phase of the estrous cycle. Cows in the group that received DE were administered one E2 implant at Hour 0, and additional implants were administered at 8-h intervals through Hour 40; then, two implants were removed at Hours 48 and 56, and one implant was removed at Hour 64.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Serum and milk progesterone in Syncro-Mate-B treated postpartum beef cows.

Fifteen post-partum (61.5+/-6.1 days) cyclic beef cows (4.1+/-0.3 years old) were randomly assigned to receive the Syncro-Mate-B (SMB) treatment on day 0 (estrus), day 9 or day 18 of their cycle with implant removal nine days later. An additional five post-partum (41.7+/-5.6 days) beef cows (3.2+/-0.4 years old) not detected in estrus and without corpora lutea also received the SMB treatment. Blood samples (10ml) were obtained via venipuncture on the day of implantation and one, three, five, seven and nine days after implantation and ten days after the post-treatment estrus. Milk samples (25 ml) were obtained by hand stripping at the same periods. Nineteen of twenty cows were synchronized, i.e. estrus occurred within five days of implant removal. Progesterone concentrations in both serum and milk were similar and followed similar patterns for each group. The day-9 treated cows had greater serum and milk progesterone concentrations than the other groups of cows on days 1, 3, and 5 after implantation. In conclusion, cows treated with SMB had similar serum and milk progesterone concentrations, endogenous progesterone secretion was inhibited by SMB treatment and the inhibition was influenced by prior luteal function.

Journal Article↗
PubMed2003

Effects of ram introduction after the second prostaglandin F2 alpha injection on day 11 on the LH surge characteristics in fat-tailed ewes.

The aim of this study was to evaluate the effects of ram introduction after the second prostaglandin F2alpha (PG F2alpha) injection on day 11 on the secretion characteristics of pre-ovulatory LH surge of fat-tailed ewes. Multiparous Morkaraman ewes (n=12) were divided into three groups by balancing the groups for liveweight (BW) and body condition score (BCS). On the day of second PGF2 alpha injection (0 h), performance tested rams (n=2) were either introduced to the ewes at 0 h (ram 0 group, n=4) or at 18 h (ram 18 group, n=4) or were not introduced (control group, n=4). Blood samples were collected at 6, 18, 42, 48, 56, 62, 66, 70, 74, 78 and 90 h for the determination of pre-ovulatory LH surge. BCS and BW during the experimental period were 2.2 +/- 0.2 units and 50.9 +/- 2.3 kg, 2.4 +/- 0.4 units and 49.2 +/- 6.2 kg, 2.1 +/- 0.3 units and 45.9 +/- 4.4 kg, respectively for the ram 0, ram 18 and control groups (p > 0.05). No significant difference was observed in LH surge characteristics for the experimental groups. Peak LH concentrations were also not different between groups (p > 0.05) and they were 12.2 +/- 8.3, 29.1 +/- 9.9 and 15.8 +/- 9.5 microg/l for the ram 0, ram 18 and control groups, respectively. There was, however, a significant correlation between peak LH concentrations and BCS (p < 0.05, R2=0.373). In conclusion, it appears that, compared with ram introduction, variability in body condition of the ewe has much pronounced effect on the amount of LH secreted after the usage of two PGF2 alpha injections (11 days apart) as a tool for oestrus synchronization.

Animals↗
PubMed2006

Influence of premature induction of a luteinizing hormone surge with gonadotropin-releasing hormone on ovulation, luteal function, and fertility in cattle.

We tested the hypothesis that luteal function and fertility would be reduced in cattle induced to ovulate prematurely compared with those ovulating spontaneously. Estrus was synchronized in 56 beef cows (24 that were nonlactating and 32 that were nursing calves). At 6.4 +/- 0.1 d after estrus, all follicles > or = 5 mm were aspirated (day of aspiration = d 0) with a 17-gauge needle using the ultrasound-guided transvaginal approach. On d 1.5 and 2, cows were administered 2 luteolytic doses of PGF2alpha. Ovarian structures were monitored by transrectal ultrasonography from d -2 to 12, or ovulation. Emergence of a new follicular wave occurred on d 1.7 +/- 0.1. When the largest follicle of the newly emerged wave was 10 mm in diameter (d 4.8 +/- 0.1), cows were assigned on an alternating basis to receive 100 microg of GnRH (GnRH-10; n = 29) to induce ovulation or, upon detection of spontaneous estrus, to the spontaneous (SPON) treatment (n = 24). Cows were bred by AI at 12 h after GnRH (GnRH-10) or 12 h after the onset of estrus (SPON) as detected using an electronic surveillance system. Blood samples were collected every other day beginning 2 d after ovulation until pregnancy diagnosis 30 d after AI. Ovulation and AI occurred in 29/29 cows in the GnRH-10 and in 24/24 cows in the SPON treatment. Ovulation occurred later (P < 0.05) in the SPON (d 7.7 +/- 0.1) than GnRH-10 (d 6.8 +/- 0.1) treatment. Double ovulations were detected in 47% of cows, resulting in 1.5 +/- 0.1 ovulations per cow. Diameters of the ovulatory and the second ovulatory (in cows with 2 ovulations) follicles were greater (P < 0.05) in the SPON (12.0 +/- 0.3 mm and 10.5 +/- 0.4 mm, respectively) than in the GnRH-10 (10.7 +/- 0.1 mm and 9.2 +/- 0.3 mm) treatment. Cross-sectional areas of luteal tissue and plasma concentrations of progesterone during the midluteal phase were greater (P < 0.05) in the SPON (3.62 +/- 0.2 cm2 and 6.4 +/- 0.3 ng/mL) than in the GnRH-10 (3.0 +/- 0.2 cm2 and 5.4 +/- 0.2 ng/mL) treatment. The conception rate to AI in the SPON (100%) treatment was greater (P < 0.05) than in the GnRH-10 (76%) treatment. The animal model used in this study resulted in unusually high conception rates and double ovulations. In conclusion, premature induction of the LH surge reduced the diameter of ovulatory follicle(s), the luteal function, and the conception rate to AI.

Animals↗