UNASSIGNED: Sexed semen (SS), a reproductive biotechnology tool, can alter the sex ratio of offspring in bovines. This study elucidates a comparative analysis of estrus-related parameters influencing conception rate and pregnancy losses under field conditions between conventional and SS.
UNASSIGNED: In the present study, artificial insemination with (SS; n = 143) and conventional semen (CS; n = 143) was performed at spontaneous estrus, i.e., 16-18 h after the onset of estrus signs, to analyze their comparative evaluation in terms of conception rates in crossbred cows under field conditions. Different parameters such as age, parity, body condition score (BCS), estrus duration, inter-estrus interval (IEI), diameter of pre-ovulatory follicle (DPOF) at estrus, and cervical mucus properties (pH and spinnbarkeit [SBK]) were recorded for each cow.
UNASSIGNED: The first insemination conception rates for sexed and conventional semen were 55.24% and 63.63% whereas the overall conception rates were 49.14% and 57.37% on days 35 and 75 post-insemination, respectively, with no significant difference (p > 0.05). Conception rates between sexed and CS inseminations were statistically significant (p < 0.01), whereas factors such as age, parity, BCS, DPOF, IEI), and SBK value exhibited no substantial variance (p > 0.05) for both types of semen straw.
UNASSIGNED: SS straws yielded a conception rate equivalent to CS straws, with estrus duration being the key factor affecting conception under field conditions.

UNASSIGNED: Norwegian Red has been shown to have high levels of estrus behavior under experimental conditions. However, the estrus behaviors of Norwegian Red cows have not been studied under commercial conditions.
UNASSIGNED: A herd of 89 Norwegian Red cows housed in free stalls on concrete, slatted floors, were continuously video monitored for 21 days. Ovarian cyclicity was confirmed in a final study sample group (n = 18) using milk progesterone concentrations. All mounting and standing activities were recorded, and the duration of mount estrus, standing estrus and the differences between these; prestand and poststand, were determined. The cycle stages metestrus, diestrus and proestrus were estimated based on the starting time and ending time of mount estrus.
UNASSIGNED: All cows in the final study sample group exhibited the primary estrus sign, \'standing to be mounted\' during estrus. Two (11%), eleven (61%) and six (33%) cows exhibited the behavior \'standing to be mounted\' during metestrus, diestrus and proestrus, respectively. The number of mounts initiated by individual cows was higher during mount and stand estrus than during the rest of the estrous cycle. This study reports a median duration of mount estrus and stand estrus of 21.0 h (interquartile range (IQR) 15.0 to 27.3) and 14.3 h (IQR 12.0 to 18.8), respectively. The median counts per hour of all mount behaviors were 8.6 (IQR 5.6 to 11.3), 1.51 (IQR 0.3 to 3.8) and 1.7 (IQR 0.8 to 6.0) for standing estrus, prestand and poststand, respectively.
UNASSIGNED: This study shows that under commercial conditions the Norwegian Red cow displays a high level of mount and stand activity associated with estrus.

Field data indicate that a longer period of estrus prior to ovulation correlates positively with fertility. To test the hypothesis that the duration of exposure to estrogens prior to progesterone dominance influences endometrial function, we used anestrous mares to simulate varying durations of estrus (3 groups of 5 mares): long (LE), short (SE), and no estrus (NE), as determined by the duration of estradiol priming prior to progesterone treatment: 7, 2 and 0 days for the LE, SE and NE, respectively. Endometrial biopsies were recovered 4 days after progesterone administration in all groups for real time quantitative reverse transcription PCR (RT-qPCR) and immunohistochemical analyses. A total of 17 genes believed to contribute to a \"receptive endometrium\" for embryo development and viability were evaluated by RT-qPCR. Of the genes evaluated, the expression of FGF-2 (fibroblast growth factor-2) decreased with increased length of preceding estrus, whereas P19 (uterocalin) expression was higher in the LE than in the SE or NE groups. In conclusion, a lower abundance of FGF-2 and higher abundance of uterocalin, a lipocalin protein known to play an important role in providing lipids to the embryo, could contribute to a more receptive endometrium in mares following a long estrus.

The objectives of the present study were to assess the effect of permanent contact of teasers without copulation on the interval from controlled internal drug release (CIDR) removal to estrus onset, estrus duration, ovulation time, number of ovulations, and interval from CIDR removal to ovulation time on estrus-synchronized Boer goats. During the fall season, a controlled randomized design experiment with two groups, control (CON; n = 18) and treatment (TRE; n = 18), was performed. The TRE group was maintained permanently in a pen with an aproned buck immediately after CIDR removal. The CON group was maintained in a different pen without permanent exposure to the male. All females were estrus synchronized with CIDR maintained in the vagina for 7 days and received 50 μg of GnRH im at device insertion and 5 mg of natural prostaglandin F-2α at device removal. Females were considered to be in estrus when they accepted mounting by the aproned bucks. Estrus was detected four times a day after CIDR removal (at 6 AM, 12 noon, 6 PM, and 12 midnight) using bucks with canvas apron as teasers. The ovulation time and number of ovulations were assessed by transrectal ultrasonography starting 24 hours after estrus onset and repeated every 6 hours until complete ovulation was detected. The estrus onset for the CON group was 44.0 ± 8.3 hours and for the TRE group, it was 37.0 ± 7.7 hours (P = 0.01). Estrus duration from the CON group was 43.7 ± 9.2 hours and for the TRE group, it was 38.3 ± 6.6 hours (P = 0.05). The first, last, and mean ovulation times for the CON group were 32.4 ± 5.3, 38.4 ± 3.4, and 35.4 ± 3.9 hours, and for the TRE group, the times were 31.8 ± 2.8, 36.7 ± 3.0, and 35.8 ± 3.6 hours, respectively (P = 0.85, P = 0.23, and P = 0.82, respectively). The number of ovulations for the CON and TRE groups was 2.6 ± 0.7 and 2.6 ± 0.6 ovulations, respectively (P = 0.96). The interval time for CIDR removal to ovulation for the CON group was 79.2 ± 8.2 hours and for the TRE group, the interval time was 73.2 ± 6.2 hours (P = 0.05). It was concluded that the permanent presence of male without copulation with estrus-synchronized does hastened estrus onset, reduced estrus duration, and decreased the interval time from CIDR removal to ovulation without modification of ovulation time and number of ovulations in Boer goats.