Evidence for quadratic association between serum anti-Müllerian hormone (AMH) concentration and fertility in dairy cows.

In cattle, results of some but not other studies indicated there has been an association of circulating anti-Müllerian hormone (AMH) concentration with reproductive variables. Considering the inconsistency in results among previous studies, there was evaluation of associations between circulating AMH and reproductive performance in dairy cows, and to this end, the prevailing data of serum AMH concentration and reproductive variables were used (n = 172). Preliminarily, association of AMH concentration with reproductive indices were analyzed using linear and quadratic models. Subsequently, cows were categorized based on AMH concentrations in four equal quartiles, including cows with the least (Q1; n = 43), moderately lesser (Q2; n = 43), moderately greater (Q3; n = 43) and greatest (Q4; n = 43) AMH concentrations, and reproductive variables were compared among the respective AMH quartiles. Initially, assessments indicated reproductive variables were not linearly associated with serum AMH (P > 0.05); however, for all reproductive variables except days to first breeding service (DFS) there was a quadratic association with serum AMH (P < 0.05). Results from analysis of reproductive performance in various AMH quartiles indicated there was a longer period of DFS for cows in Q3 than Q1 (P < 0.05). First postpartum insemination to conception and calving to conception intervals were shorter for cows in Q3 than Q1 and Q4 (P < 0.05) and for cows in Q2 than Q1 (P < 0.05). In conclusion, results from the present study indicate cows with intermediate AMH concentrations had greater reproductive performance.

Inferior fertility and higher concentrations of anti-Müllerian hormone in dairy cows with longer anogenital distance.

Anogenital distance (AGD), which is an indicator of prenatal androgen exposure, has been reported to have high variability and negative association with fertility in dairy cows. Prenatal exposure to androgens could influence the development of primordial follicles and size of ovarian reserve, which is related to reproduction. However, the relationship between AGD and size of ovarian reserve has not been studied. Therefore, the present study was conducted to determine the association between AGD and circulating anti-Müllerian hormone (AMH), as an indirect marker of ovarian reserve, and to evaluate serum AMH concentration and reproductive performance in dairy cows with short and long AGD. Anogenital distance was measured 28 to 32 d postpartum, and based on the median of AGD, cows were divided into 2 subsets including short (n = 43) and long (n = 43) AGD groups. Afterward, serum AMH was evaluated on the day of estrus in cows that were estrus-synchronized. Furthermore, reproductive data of dairy cows during the previous lactation period were collected from the herd database. Concentrations of serum AMH tended to be positively associated with length of AGD, and there was a tendency for higher serum AMH concentrations in the long (634.89 ± 74.52 pg/mL) than short (451.39 ± 45.92 pg/mL) AGD group (0.05

0.05). Calving to conception interval was prolonged in long (194.30 ± 17.12 d) than short (147.14 ± 13.11 d) AGD cows (P ≤ 0.05). In conclusion, the present study revealed elevated serum AMH concentrations and poor reproductive performance in cows with longer AGD compared with cows with shorter AGD.

Nulliparous and primiparous cows produce less fertile female offspring with lesser concentration of anti-Müllerian hormone (AMH) as compared with multiparous cows.

Nutritional partitioning to fetal development differ among nulliparous, primiparous and multiparous cows, leading to birth of smaller calves to nulliparous and primiparous than multiparous dams. The prenatal nutritional state could influence ovarian reserve and fertility in the adult offspring. The effect of maternal parity on ovarian reserve and reproduction of female offspring, however, has not been investigated in cattle. Accordingly, a retrospective research was conducted to study reproductive variables in nulliparous- (n = 310), primiparous- (n = 236) and multiparous-born (n = 323) female offspring during the first four lactation periods in dairy cows. Additionally, anti-Müllerian hormone (AMH), as a reliable marker of ovarian reserve, was measured in a subset of nulliparous- (n = 51), primiparous- (n = 51) and multiparous-born (n = 49) female offspring. Birth weight in multiparous-born calves was greater than that in nulliparous- and primiparous-born calves (P < 0.01). Days to first service was shorter in multiparous-born female offspring as compared with nulliparous- and primiparous-born female offspring (P < 0.05). First service conception rate, proportion of repeated breeders, service per conception and calving to conception interval were greater in multiparous-born than nulliparous-born cows (P < 0.05). Cumulative culling rate was greater in primiparous-born cows than nulliparous- and multiparous-born cows (P < 0.05). The AMH concentration was greater in multiparous-born than nulliparous- and primiparous-born cows (P < 0.05). In conclusion, the present study revealed that in comparison with multiparous cows, nulliparous and primiparous cows, particularly nulliparous cows, produce female offspring with lesser reproductive performance and smaller size of ovarian reserves.

Temporal effect of maternal heat stress during gestation on the fertility and anti-Müllerian hormone concentration of offspring in bovine.

Ovarian reserve has been suggested as an important contributing factor of reproductive success in bovine. Size of ovarian reserve is determined during fetal period and it could be altered by environmental factors, with which the dam is exposed. Maternal heat stress could impair placental function and fetal development; however, there is limited information on the impact of prenatal heat stress on fertility and ovarian reserve in the offspring. Therefore, a retrospective study was conducted, in which fertility parameters and AMH concentration, as a reliable marker of ovarian reserve in bovine, were studied in the offspring of dams that had been exposed to heat stress during the first (FTE), second (STE) or third (TTE) trimester of gestation and the offspring of dams unexposed to heat stress (US). Additionally, postpartum exposure of offspring with heat stress was considered in the model to adjust the statistical analysis in this regard. Days to first service (DFS) and calving to conception interval (CCI) were prolonged in exposed than unexposed cows (P < 0.05). Days to first service and CCI were also longer in STE compared with FTE cows (P < 0.05). First service conception rate was lower in TTE than UN cows (P < 0.05). The proportion of repeat breeders was higher in exposed compared with unexposed cows (P < 0.05). Service per conception was higher in STE and TTE than UN cows (P < 0.05). Culling rate between different periods of lactation was also higher in exposed than unexposed cows (P < 0.05). Finally, AMH concentration was lower in STE and TTE than UN cows (P < 0.05); moreover, it was lower in STE compared with FTE cows (P < 0.05). In conclusion, the present study revealed detrimental effects of maternal heat stress on fertility, productive longevity and ovarian reserve in the offspring. In this context, the second and third trimesters appeared to be more critical periods.

Ocular fungal flora from healthy horses in Iran.

OBJECTIVE: This study was carried out in order to isolate and identify the normal conjunctival fungal flora from Caspian miniature, Thoroughbred, Turkmen and Persian Arab breeds in Tehran, Iran. MATERIALS AND METHODS: A total of seventy-two adult healthy horses were studied. Ocular samples were collected from right and left eyes by using sterile cotton swabs; samples were cultured on Sabouraud dextrose agar and incubated at 30°C for 7-10 days. Molds and yeasts were identified using macro and micro-morphological and physiological characteristics. RESULTS AND CONCLUSION: Number of fungal colonies per eye varied between 0 and 123 colony forming units (CFUs). The most predominant fungal isolates were Aspergillus (19.9%), Rhizopus (15.9%) and Penicillium (15.1%). No significant differences were observed between types of eye fungal floras in different breeds. Caspian miniature horses had significantly the highest number of fungal isolates in compare with other breeds (P<0.001), however no significant difference was observed among other breeds under study. The fungal isolates were almost the same as with studies performed in other countries, although differences in species isolated could be related to geographic and climate difference.

Reduced anti-Müllerian hormone (AMH) in mares with hemorrhagic anovulatory follicles.

Anti-Müllerian hormone (AMH) has been observed to decrease with the development of hemorrhagic anovulatory follicles (HAFs) in mares. Two studies were conducted to evaluate AMH concentration in mares with HAFs compared to seasonally anoestrous and cyclic mares, and to elucidate changes of AMH with the development of luteinised unruptured follicles (LUFs). In study 1, AMH and progesterone were evaluated in seasonally anoestrous, anovulatory (with HAF) and cyclic mares (at mid luteal phase). In study 2, mares in control and LUF groups were treated with 1500 IU/case hCG when they had a ≥32-mm follicle and an endometrial oedema score of three (day 0). Mares in the control group received no further treatment. Mares in the LUF group received 1.7 mg/kg flunixin meglumine at the time of hCG administration, and 12, 24 and 36 h after it. Ultrasonography and blood collection for AMH and progesterone measurement were performed on days 0, 1, 2, 4, 6 and 8. In study 1, AMH concentration was lower in seasonally anoestrous and HAF mares than cyclic mares (P<0.05). Progesterone concentration did not differ between HAF and cyclic mares (P>0.05). In study 2, AMH was not different between LUF and control mares (P>0.05); however, progesterone had a lower concentration and a delayed rise after hCG administration in LUF mares compared with the control group (P<0.05). The results indicated that similar to seasonally anoestrous mares, AMH concentrations decreased in mares with HAFs. LUFs were also found to be functionally different from HAFs.

Parallel distribution of sexes within left and right uterine horns in Holstein dairy cows: evidence that the effect of side of pregnancy on sex ratio could be breed-specific in cattle.

Dissimilar distribution of male and female calves within left and right uterine horns has been observed in beef cows. A retrospective study was conducted to investigate the effect of side of pregnancy on secondary sex ratio in Holstein dairy cows. Data associated with sex of calves, side of pregnancy, sire, dam, parity number of dam, AI technician, season and year were retrieved from the database of a Holstein dairy farm. In total, data consisted of 6515 birth records from 3155 dams and 244 sires across years 2001-2010. Data were analyzed using logistic regression. There was no difference in proportion of male and female calves between left (52.9% and 47.1%, respectively) and right (53.2% and 46.8%, respectively) uterine horns (P>0.05). AI technician, year, season and parity of dam did not affect secondary sex ratio (P>0.05). Secondary sex ratio of left and right uterine horns, and consequently, overall secondary sex ratio (53.1%) were skewed toward males as compared with hypothetical secondary sex ratio of 50% (P<0.05). Incidence of right pregnancy (60.5%) was higher than hypothetical 50% incidence of right pregnancy. In conclusion, the present study revealed similar secondary sex ratio of calves between left and right uterine horns in Holstein dairy cows.

More male calves born after Presynch-Ovsynch protocol with 24-hour timed AI in dairy cows.

Various factors including synchronization treatments have been reported to influence sex ratio of offspring in cattle. The present study was conducted to investigate the effect of treatment with Presynch-Ovsynch protocol on sex ratio of offspring in Holstein dairy cows. Healthy Holstein cows (N = 1102) were randomly assigned to Presynch-Ovsynch (N = 564) or control (N = 538) group by parity. Cows in Presynch-Ovsynch group received two administrations of PGF(2)α 14 days apart started at Days 23 to 27 postpartum. Twelve days after the second PGF(2)α treatment, Ovsynch protocol, consisting of an administration of GnRH followed by administration of PGF(2)α 7 days later and a final administration of GnRH given 48 hours after the third PGF(2)α treatment, began. Cows were subjected to fixed-time AI 24 hours after the last administration of GnRH. Cows in control group received no treatment and were inseminated 12 hours after standing estrus. Sex of calves conceived by the first service postpartum was determined after parturition and used for calculation of sex ratio. Parity, season, sire, and calving to conception interval were considered as covariates in statistical analysis. Sex ratio of calves in Presynch-Ovsynch group (1.64) was higher than that in control group (1.09; odds ratio = 1.51; P < 0.05). Moreover, male to female ratio was higher in cows conceived in summer, fall, and winter than in cows that conceived in spring (P < 0.05). In conclusion, cows treated with Presynch-Ovsynch protocol and inseminated 24 hours after the last GnRH administration of Ovsynch had a higher sex ratio than cows inseminated 12 hours after standing estrus.