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PubMed2006

Factors affecting reproductive performance of Holstein heifers.

The objectives were to evaluate factors affecting reproductive performance of dairy heifers. Holstein heifers (6389) were housed in a feed lot located in Parma, ID. Each week heifers weighing > or =290 kg were initiated in the reproductive program, which consisted of one injection of PGF(2alpha) and AI on detection of estrus. Heifers not inseminated by 11 days after the initiation of the breeding program received a second injection of PGF(2alpha). Pregnancy was diagnosed at 40+/-3 and 90+/-3 days after AI. Average daily minimum temperature (ADMnT), average daily maximum temperature (ADMxT), and average daily rainfall (ARF) were recorded between 15 days prior to and 15 days after the day of AI or the day of initiation of the breeding program. Exposure to air temperature was classified as: cold stress (CS=ADMnT< or =4 degrees C), no stress (NS=ADMnT>4 degrees C and ADMxT<29 degrees C), and heat stress (HS=ADMxT> or =29 degrees C). Exposure to rainfall was classified as above (HRF) or below (LRF) the mean for the period in question. Heifers were classified according to body weight at initiation of the breeding program as thin (TH<340 kg); moderate (MD=340-365 kg); and heavy (HY>365 kg). Service sire was associated with conception rate at 40 and 90 days after first AI. Although exposure to air temperature was not correlated with conception rate at 40 days after first AI, heifers exposed to cold stress had smaller conception rates at 90 days after first AI because they were more likely to lose pregnancy between 40 and 90 days of gestation. The proportion of heifers inseminated after initiation of the breeding program was correlated with body weight and exposure to cold stress. Exposure to cold stress was also correlated with the proportion of heifers conceiving within 11 and 22 days after initiation of the breeding program. From this study a correlation was established between body weight and rate of insemination and between the exposure to cold stress and reproductive efficiency of Holstein heifers.

Abortion, Veterinary↗
PubMed2006

Effect of sperm numbers and time of insemination relative to ovulation on sow fertility.

We examined the effect of inseminating mixed parity sows (n=231) once with fewer sperm at different times relative to ovulation. Lactation length was 19 days and sows received an IM injection of 600 IU equine chorionic gonadotrophin (eCG) 12 h before weaning. At 80 h after eCG injection, sows received an IM injection of 5 mg porcine luteinizing hormone (pLH). Predicted time of ovulation (PTO) was 38 h after pLH injection. Sows were assigned by parity to receive a single transcervical artificial insemination (AI) at either 6 or 24 h before PTO with semen doses containing either 2.5 or 1.25x10(9) sperm. A positive control group of sows (n=49) was subject to conventional AI 24 and 6 h before PTO. Detection of estrus was performed in the presence of a boar and only sows exhibiting estrous behavior at the assigned time of AI were included in the study. Farrowing rate for sows receiving 2.5x10(9) sperm at 6 h before PTO was greater than that for sows receiving 1.25x10(9) sperm at 24 h before PTO (85% versus 61%, P<0.05). All other groups were intermediate. There was no effect of time of AI or sperm numbers on subsequent litter size. These data indicate that single insemination of fewer sperm may compromise sow fertility, even when performed transcervically, if not appropriately timed relative to ovulation.

Animals↗
PubMed2004

Plasma concentrations of inhibin A in cattle with follicular cysts: relationships with turnover of follicular waves and plasma levels of gonadotropins and steroid hormones.

We investigated the profiles of circulating levels of inhibin A and total inhibin in beef cows with follicular cysts in relation to the patterns of follicular development and circulating gonadotropins and steroid hormones. Turnover of follicular waves was monitored in five cows every 2 days for 70 days from 10 days after detection of estrus without ovulation. The mean interwave intervals were 19.6 +/- 1.0 days (n = 18 waves with cysts from the five cows). Circulating levels of inhibin A were approximately 170 pg/ml before emergence of follicular waves with cysts and increased (P < 0.05) concomitantly with follicle emergence. High concentrations of inhibin A (greater than 300 pg/ml) were noted for 7 days during the growth phase of cystic follicles, but inhibin A levels decreased gradually when development of the cysts reached a plateau. This profile of inhibin A was similar to those of total inhibin and estradiol, but was inversely related to the changes in plasma FSH concentrations. LH pulse frequency and mean concentrations of LH in cows with cysts were higher than those observed in the luteal phase of normal cyclic cows. These results indicate that the capacity to secrete inhibin, as well as estradiol, is maintained in cystic follicles, the growth of which is extended by LH secretion at levels greater than those seen in the normal luteal phase. Inhibin A plays an important role in the extension of interwave intervals by suppressing recruitment of a new cohort of follicles.

Analysis of Variance↗
PubMed2004

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.

Animals↗
PubMed2005

Reproductive performance in anestrous dairy cows following treatment with two protocols and two doses of progesterone.

The objectives of this study were to evaluate the effect using two doses of progesterone (P4) releasing devices in two different programs on reproductive performance of anestrous dairy cows. Cows (n = 1555) not detected in estrus by 10 d before the planned start of the seasonal breeding program and in which no CL was palpable were treated with an intravaginal P4-releasing device ('Single'; approximately 1.56 g of P4) or a modified device with triple the normal P4 dose ('Triple'; approximately 4.7 g of P4). The devices were in place for either 6 d ('Short') or 8 d ('Long'), with 1mg estradiol benzoate (EB) given 24 h after device removal. The 'Long' program also included treatment with 2 mg EB at device insertion. The Long program resulted in a higher first service conception rate (RR = 1.18 (95% CI = 1.03-1.33); P = 0.02), but had no effect on the 28-d, 56-d or final pregnancy rate compared to the Short program. There were no effects of dose of P4 on any outcome. In conclusion, the Long compared to the Short program, but not the dose of P4, improved first service conception rates in anestrous cows.

Administration, Intravaginal↗
PubMed2005

Resynchronization of ovulation and timed insemination in lactating dairy cows I: use of the Ovsynch and Heatsynch protocols after non-pregnancy diagnosis by ultrasonography.

The objective was to compare pregnancy rates and pregnancy losses in lactating dairy cows that were diagnosed not pregnant and re-inseminated following either the Ovsynch or Heatsynch protocols. Also evaluated were the effects of stages of the estrous cycle, ovarian cysts and anestrus on pregnancy rates for both treatments. Non-pregnant cows (n = 332) as determined by ultrasonography on day 27 post-AI (study day 0) were divided into two groups. Cows in the Ovsynch group (n = 166) received GnRH on day 0, PGF2alpha on day 7, GnRH on day 9, and timed AI (TAI) 16 h later (day 10). Cows in the Heatsynch group (n = 166) received GnRH on day 0, PGF2alpha on day 7, estradiol cypionate (ECP) on day 8, and TAI 48 h later (day 10). Cows detected in estrus on days 8 and 9 were inseminated and included in the study. On day 0, cows were classified according to different stages of the estrous cycle, or presence of ovarian cysts or anestrus. Pregnancy rates were evaluated 27, 45 and 90 days after resynchronized AI. Overall, there was no difference in pregnancy rates on days 27, 45 and 90 between cows in the Ovsynch (25.2, 17.5, and 13.9%) and Heatsynch (25.8, 19.9, and 16.1%) groups. There was no difference in pregnancy losses from days 27 to 45 and days 45 to 90 for cows in the Ovsynch (25.0 and 17.9%) and Heatsynch (14.7 and 10.3%) groups. However, pregnancy rates were increased when cows in metestrus were subjected to the Heatsynch protocol and cows with ovarian cysts were subjected to the Ovsynch protocol.

Animals↗
PubMed2005

Fertility after deep intra-uterine artificial insemination of concentrated low-volume boar semen doses.

UNLABELLED: Boar semen can be successfully frozen - highly packed - in small containers (medium-straw, MS or MiniFlatPack, MFP). The use of deep intra-uterine artificial insemination (DIU-AI) can make possible the deposition of small volumes of this thawed, non re-extended semen deeply intra-uterine, close to the sperm reservoir. The present experiments studied the fertility achieved after single or double DIU-AI per oestrus, with special attention to the interval between AI and spontaneous ovulation. Semen from two boars of proven fertility was frozen in MS or MFP holding 1 x 10(9) total spermatozoa. Multiparous (2-5 parity, n=42) crossbred sows were checked for oestrous behaviour after weaning and the occurrence of spontaneous ovulation was checked with transrectal ultrasonography (TUS) to establish the mean interval between onset of oestrus (OO) and ovulation which was found to be when approximately 2/3 of the oestrus period has passed. The sows were, in the following standing oestrus, subjected to DIU-AI using thawed semen from either MS (n=20) or MFP (n=22), inseminated without further re-extension. The sows were randomly allotted to one of three groups: (1) single DIU-AI 8 h before expected ovulation (control group, n=19); (2) single DIU-AI 4 h before expected ovulation (treatment group S, n=15); and (3) double DIU-AI 12 and 4 h before expected ovulation (treatment group D, n=8). Occurrence of spontaneous ovulation was confirmed by TUS, performed as during the first oestrous period and used to determine the real interval of DIU-AI and ovulation. Pregnancy was also confirmed by TUS 28 days after OO in those sows not returning to oestrus. These sows were slaughtered (30-45 days of pregnancy), and the appearance of the reproductive tract and ovaries, the number of live and dead foetuses, of implantation sites and of corpora lutea (CL) were recorded. Sows (n=9) returning to oestrus ("open") were re-inseminated (either once [n=4] or twice [n=5]) the following oestrus with either MFP (n=5) or MS (n=4) and slaughtered 12-14 h post-ovulation for recovery of tubal oocytes and of spermatozoa from the uterotubal junctions (sperm reservoir), to assess the degree of effectiveness of sperm transport. Post-thaw sperm motility was 44.3+/-3.21% in MFP and 42.8+/-0.72% for MS (LSmean+/-S.E.M., n.s.), and did not significantly change from thawing to AI. The DIU-AI could be performed in all sows, but insertion was difficult (slow >5 min) in 5/42 sows. Four of these sows returned to oestrus. Pregnancy rate averaged 35% (group D: 25%, group S: 40%, control: 36%, n.s.). The interval between DIU-AIs and spontaneous ovulation varied largely, ranging from -13 to -3 h for group C, for group S from -11 to +3 h and for group D from -17 to -4 h. Pregnancy rates were clearly related to the interval DIU-AI and ovulation, being highest (60%, 12/20) when AI occurred between 8 and 4 h before spontaneous (not expected) ovulation. The number of implantation sites ranged 6-22 (n.s. among groups), and the number of alive foetuses 2-11 (n.s. among groups). Implantation rate (total number of implantations/CL) ranged 48.0-69.7% being highest in the D-group (P<0.05). The examination of the "open" sows slaughtered 12-14 h post-ovulation revealed few recovered oocytes were fertilized (approximately 10%). Only 40% of oocytes had spermatozoa bound to the zona pellucida, not more than two spermatozoa per oocyte. Moreover, low sperm numbers (approximately 4000) were found in the sperm reservoirs (UTJs), irrespective of using single or double DIU-AI (n.s.). The highest values (P<0.05) for these variables were recorded when DIU-AI (either single or double [second AI]) occurred 4-8 h before ovulation, especially when MFP-semen was used (P<0.05). IN CONCLUSION: (1) DIU-AI can be easily performed in most sows; (2) pregnancies can be obtained by the DIU-AI of low volumes of highly concentrated frozen-thawed boar semen, once or twice during oestrus, but fertility is still low, probably owing to an unsatisfactory sperm transport when expected and real ovulation differ; and (3) fertility is related to the interval DIU-AI and ovulation which should be -8 to -4 h of spontaneous ovulation and to the package, MFP having shown better results in vivo. The results stress the need for careful, and frequent, control of oestrus signs.

Animals↗
PubMed2005

Comparison of synchronization of ovulation with timed insemination and exogenous progesterone as therapeutic strategies for ovarian cysts in lactating dairy cows.

The objective of this study was to compare the effectiveness of the Ovsynch and controlled internal drug releasing (CIDR) protocols under commercial conditions for the treatment of cystic ovarian disease in dairy cattle. A total of 401 lactating dairy cows with ovarian cysts were alternatively allocated to two treatment groups on the day of diagnosis. Cows in the Ovsynch group were treated with GnRH on Day 0, PGF2alpha on Day 7, GnRH on Day 9, with timed insemination 16-20 h later. Cows in the CIDR group were treated with a CIDR insert on Day 0 for 7 days; on Day 7, the CIDR was removed, and cows were treated with PGF2alpha. All cows in the CIDR group were observed for estrus and cows exhibiting estrus within 7 days following removal of the CIDR and PGF2alpha administration were inseminated. The outcomes of interest for this experiment were the likelihood to be inseminated, return to cyclicity (determined by a CL on Day 21), conception and pregnancy rates. Data for these variables were analyzed using logistic regression. The percentage of cows inseminated in the Ovsynch and CIDR groups were 82 and 44%, respectively. Cows in the Ovsynch group were 5.8 times more likely to be inseminated than cows in the CIDR group. Cows with a low BCS were 0.48 times less likely to be inseminated than cows with a high BCS. The percentage of cows with a CL on Day 21 for the Ovsynch and CIDR groups was 83 and 79%, respectively (P > 0.05). Cows with a low BCS were 0.49 times less likely to have CL on Day 21 than cows with a high BCS. Conception and pregnancy rates for cows in the Ovsynch group were 18.3 and 14.4%, respectively. Conception and pregnancy rates for cows in the CIDR group were 23.1 and 9.5%, respectively. There was no significant differences between conception or pregnancy rates in cows in both groups. Primiparous cows were 2.6 times more likely to conceive than multiparous cows. In conclusion, the results of this study suggested that fertility was not different between cows with ovarian cysts treated with either the Ovsynch or the CIDR protocols in this dairy herd. In addition, primiparous cows had an increased likelihood for conception compared to multiparous cows, and cows with a low BCS were less likely to be inseminated or have a CL on Day 21, regardless of treatment.

Animals↗
PubMed2005

Strategies for improving fertility in the modern dairy cow.

The high producing dairy cow of the 21st century is subfertile during lactation. Our objectives are to characterize physiological periods limiting reproductive performance and to describe integrated management strategies to improve pregnancy rates. Ovarian recrudescence with normal re-occurring estrous cycles and restoration of fertility to first service are associated with a reduced occurrence of periparturient metabolic and reproductive disorders. Marked negative changes in energy balance and reduced immunocompetence influence gonadotropic and metabolic hormones. Induced ovarian inactivity was associated with enhanced uterine involution. Post-partum health and reproductive performance were improved when by-pass lipids enriched in polyunsaturated fatty acids were fed in the pre- and post-partum periods. Pharmaceutical control of follicle, CL, and uterine function with PGF, GnRH and intravaginal progesterone releasing inserts, has permitted development of more optimal timed-insemination programs for first service. Likewise, resynchronization of nonpregnant cows coupled with the use of ultrasound for early pregnancy diagnosis provides the opportunity for a second timed-insemination within 3 days of a nonpregnant diagnosis. Bovine somatotropin (bST) increases embryo development and embryo survival when coupled with a timed-insemination program or cows detected in estrus. Presence of a conceptus alters endometrial expression of genes and proteins in response to bST and nutraceuticals (i.e., unsaturated fatty acids such as eicosapentaenoic and docosahexaenoic acid in by-pass lipids) to improve pregnancy rates. Postovulatory increases in progesterone may enhance pregnancy rates in targeted populations of lactating dairy cows, but timing and magnitude of the progesterone increases are pharmaceutically dependent.

Animals↗
PubMed2006

Effect of lameness on estrous behavior in crossbred cows.

Lameness, a common disease in crossbred dairy cows, badly affects their fertility. To elucidate, if estrous behavior, comprising of duration and expression of certain estrous behavioral sign(s) (EBS), is involved, an estrous expression score system was applied to objectively compare estrous behavior during 27 and 58 estrous periods, respectively, in 17 normal and 37 lame cows kept in a group of 200 cows under loose housing system in tropical India. The cows were detected in estrus and were closely watched daily for 30 min at 0630, 1030, 1430 and 1830 h from the beginning to the end of estrus. The duration of estrus was similar in the normal and the lame cows (18.7+/-1.2 h versus 17.2+/-0.9 h) and almost similar EBS were shown by two types of cows, albeit with varying frequency. Standing to be mounted, the highest ranking EBS was shown by equal proportions of the cows in both the groups (76.4% versus 73.0%). A lower proportion of lame cows showed head side mounting (35% versus 53%; P<0.05). The frequency of standing to be mounted events was lower in the lame than in the normal cows (2.4+/-0.4 versus 8.0+/-2.5; P<0.05). The lame cows earned non-significantly lower than normal estrous behavior score (1100+/-179 versus 1610+/-357). Further, the presence of more than one cow simultaneously in estrus enhanced the estrous behavior score in the normal (406.4+/-63.0 for one cow in estrus versus 793.0+/-146.0 for three cows simultaneously in estrus; P<0.05), but not in the lame cows. Lameness appeared to have suppressed the playful behavior during estrus probably owing to pain related stress. It is concluded that mildly lame cows appear to have normal physiological estrus. However, some of the EBS remain subdued which prone them to remain undetected for timely breeding.

Animals↗
PubMed2006

Developmental programming in sheep: administration of testosterone during 60-90 days of pregnancy reduces breeding success and pregnancy outcome.

Evidence suggests that exposure to excess steroids during critical periods of fetal development leads to reproductive disorders. Exposure of female lambs to excess testosterone (T) from Days 60 to 90 of gestation (T60-90; term, 147 days) delayed onset of the LH surge and resulted in to male-typical reproductive behavior. The objectives of this study were to test the ability of T60-90 ewes to mate, conceive and lamb during the first three breeding seasons (Years 1, 2 and 3). Pregnant Suffolk ewes were injected with T propionate in cottonseed oil (100mg, im twice weekly) or vehicle (control; C) from Days 60 to 90 of gestation. In Year 1, ewes (C=12, T60-90=12) were kept with a vasectomized ram for 3 months and markings/visual observation of copulations were recorded. Rams had paint applied to their chest to facilitate detection of estrus and mating. All C but only three T60-90 ewes were marked (P<0.001). All ewes were then estrus-synchronized with two injections of prostaglandin F2alpha (20mg, im) given 11 days apart and allowed to mate with a painted, fertile ram. Nine of 12 C and 4 of 12 T60-90 ewes (P=0.1) were mated. Based on estrus and long-term monitoring of progesterone, more C than T60-90 became pregnant (82 and 18%, respectively; P<0.01). In Year 2, to maximize ram exposure, two C and two T60-90 estrus-synchronized ewes were placed with a painted, fertile ram at a time and mated ewes were removed to a nearby pen to force mating with others. Twenty-four hour video monitoring revealed the rams mated more C than T60-90 ewes (83 and 25%, respectively; P=0.01). In both Years 1 and 2, the rams preferred C over T60-90 ewes; therefore in Year 3 rams were given access only to T60-90 ewes. Only four T60-90 estrus-synchronized ewes were placed with a painted ram at a time. Not given an option, 91% of the T60-90 ewes were marked resulting in 4 of 11 (36%; first-service pregnancy rate in the breeding herd was 91%) ewes becoming pregnant to the synchronized estrus. Collectively these studies showed that fertility in T60-90 females was severely compromised, even after overcoming ram preference for controls.

Animals↗
PubMed2000

Effect of body condition on reproductive efficiency of lactating dairy cows receiving a timed insemination.

Body condition may influence pregnancy rates to a timed insemination (Ovsynch/TAI) protocol and affect the economical performance of dairy farms. The objectives were to compare pregnancy rates using the Ovsynch/TAI protocol for the first service of lactating dairy cows with body condition scores < 2.5 (scale: 1 to 5, low BCS group) versus > or = 2.5 (control group) and to estimate the economic impact of the effect of body condition on reproductive performance. At 63 +/- 3 d post partum, cows were assigned to 2 experimental groups (low BCS = 81; control = 126), and were treated with GnRH at d 0 and with PGF2alpha 7 d later. At 48 h after PGF2alpha, cows received an injection of GnRH and were inseminated 16 h later. Pregnancy rates to the Ovsynch/TAI protocol were lower for the low BCS group than for the control group at 27 d (18.1 +/- 6.1% < 33.8 +/- 4.5%; P<0.02) and at 45 d (11.1 +/- 5.4% < 25.6 +/- 4.1%; P<0.02) after insemination. Economic analysis indicated that reducing the percentage of the herd in low body condition increases net revenues per cow per year. Body condition influenced pregnancy rates to the Ovsynch/TAI protocol.

Adipose Tissue↗
PubMed2000

Oviductal isthmic motility in relation to ovulation and endocrine changes in unrestrained sows.

This study was designed to characterize changes in the motility of the oviductal isthmus in relation to endocrine changes around ovulation in unrestrained sows in their normal environment. Oviductal isthmic motility was monitored on Polyview from 11 h prior to and up to 36 h after ovulation in 13 unrestrained multiparous sows during their second estrus after weaning, using a pressure microtransducer implanted 3 cm into the isthmus. Both the maximum, minimum and mean pressures and the frequency of phasic pressure fluctuations were high prior to ovulation but declined significantly (P<0.05) at 9 to 12 h, 13 to 16 h, 13 to 16 h and 5 to 8 h after ovulation, respectively. Plasma estradiol-17beta and prostaglandin F2alpha metabolite levels declined significantly (P<0.05) at 4 to 7 h prior to ovulation while progesterone levels increased significantly (P<0.01) at 5 to 8 h after ovulation. The decrease in the plasma estradiol-17beta levels was correlated to the decrease in maximum and mean pressures and the frequency of phasic pressure fluctuations (n=113; r=0.30, 0.25, 0.25, respectively; P<0.01) but not to the decrease in minimum pressure (n=113; r=0.17, P>0.05). Similarly, the decrease in PGF2alpha metabolite levels was correlated to the decrease in minimum, maximum and mean pressures and the frequency of phasic pressure fluctuations (n=112; r=0.43, 0.35, 0.38, 0.32, respectively; P<0.001). Conversely, the increase in plasma progesterone levels was correlated to the decrease in minimum, maximum and mean pressures and the frequency of phasic pressure fluctuations (n=113; r=-0.56, -0.70, -0.68, -0.60, respectively; P<0.001). Therefore, the pressure parameters seem to be influenced by changes in the levels of estradiol-17beta, prostaglandin F2alpha and progesterone with respect to ovulation.

Animals↗
PubMed2000

Postovulatory effect of repeated intravenous administration of ACTH on the contractile activity of the oviduct, ova transport and endocrine status of recently ovulated and unrestrained sows.

The effect of repeated intravenous administration of ACTH (Synacthen depot) on the contractile activity of the oviduct, ova transport and endocrine status was studied in 11 Swedish crossbred (Landrace x Yorkshire) multiparous sows. In the second estrus after weaning, the ACTH group (Group A, n=6) sows were administered 0.01 mg/kg body weight of ACTH every 6 h commencing 4 to 8 h after ovulation, whereas the control group (Group C, n=5) sows were administered saline solution. Immediately after standing estrus, a Millar pressure transducer was placed about 3 cm into the isthmus via a laparotomy. Blood samples for hormonal analyses and pressure recordings of the oviduct were collected from all sows until slaughter. After slaughter, the genital tract opposite to the side with the transducer was retrieved, and 3 equal isthmic segments and the first third of the uterine horn portion adjacent to the UTJ were flushed separately for ova recovery. Cortisol levels were significantly (P<0.05) elevated after ACTH administration. Progesterone and PGF2alpha metabolite levels were significantly (P<0.05) elevated only after the first ACTH administration. No significant differences (P>0.05) were seen in the mean pressure and frequencies of phasic pressure fluctuations either before or after every ACTH administration between Groups A and C. No significant difference (P>0.05) was seen in the proportion of ova recovered in the different segments between Groups A and C. It can be concluded from the present study that the administration of ACTH (0.01 mg/kg body weight) to sows at 4 to 8 h after ovulation, and after each subsequent ACTH administration, elevates cortisol levels, whereas progesterone and PGF2alpha metabolite levels are elevated only after the first treatment, and that this has no effect on the mean isthmic pressure, the frequency of phasic pressure fluctuations or ova transport.

Adrenocorticotropic Hormone↗
PubMed2001

Effect of subclinical uterine infection on cervical and uterine involution, estrous activity and fertility in postpartum buffaloes.

Nili-Ravi buffaloes (n=29) that calved normally between August and November and did not develop any clinical reproductive disorder after calving were studied for the incidence of sub-clinical bacterial infection of the uterus and its effects on postpartum reproductive efficiency. The incidence of subclinical uterine infection was 24% (7/29). Involution of the cervix and uterus was slower (P < 0.01) in the infected group than in the normal group (45.6 vs 31.1 days and 46.3 vs 35.8 days), respectively. The mean diameters of cervix and gravid horn on Day 12 post partum and on completion of involution did not differ between buffaloes of the two groups. However, the rate of involution of the cervix and the gravid horn was lower in buffaloes of the infected group (2.2 vs. 2.7 mm/day and 2.6 vs. 3.2 mm/day). The mean interval to first post partum ovulation was similar in buffaloes in the infected (35.5 days) and the normal group (33.8 days). The life span of corpus luteum formed after first ovulation was shorter (11 days) in buffaloes of both groups than that of a normal estrous cycle (15 to 17 days). The incidence of silent ovulation was apparently higher in buffaloes of the infected group (83 vs. 60%) but the difference was not significant. For the first four months after calving, the mean interval to first postpartum estrus was longer in buffaloes of the infected group (73.0 vs. 47.7 days; P < 0.01). Similarly, the average service period was longer in buffaloes of the infected group (91.0 vs. 64.8 days; P < 0.05). The overall pregnancy rate for the first four months after calving did not differ between buffaloes of the two groups. We conclude that subclinical bacterial infection of the postpartum uterus delays the cervical and uterine involution which can, in turn, delay the occurrence of first postpartum estrus and prolong the service period in buffaloes.

Animals↗
PubMed2001

Embryo transfer in Bos indicus cattle.

In the present short review superovulation treatments commonly used for Bos taurus and/or Bos indicus will be addressed with emphasis in recent superstimulation protocols associated with pharmacological manipulation of the follicular dynamics to improve donor management and potentially embryo yield. Results obtained after superovulation treatments in which the time of LH surge is selectively delayed as an attempt to improve embryo yield are presented and discussed.

Animals↗