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Precise pregnancy detection is critical for optimizing reproductive efficiency in animals. In mice, the conventional copulation plug method for pregnancy confirmation lacks reliability, particularly in inbred strains, with false-pregnancy rates exceeding 50 %. Here, to improve pregnancy detection efficiency in mice, we examined vaginal cell population changes using vaginal smear technique and analyzed MMP-9 expression in vaginal tract from day 0.5 to 6.5 of pregnancy. A total of forty-four female mice in the estrus stage were paired with sexually mature male mice for natural mating. The morning after mating was considered as embryonic day 0.5 (E0.5). Vaginal cytology was used to determine the vaginal cells of pregnant and non-pregnant mice from day 0.5 to 6.5. Furthermore, the protein and gene expression of MMP-9 were assessed through the utilization of immunohistochemistry and real-time PCR. Our findings reveal that pregnant mice display the higher number of leukocytes but the low number of nucleated/cornified epithelial cells in vagina compared to the non-pregnant counterparts. Furthermore, MMP-9 protein consistently presents in vaginal epithelial cells throughout the experimental period, with increased protein expression on day 4.5 of pregnancy followed by a decline on day 6.5 of pregnancy. This result is similar to MMP-9 gene expression, reaching the peak on day 5.5 of pregnancy. In conclusion, vaginal cytology proves effective for mouse pregnancy determination, while MMP-9 can serve as a potential biomarker for detecting pregnancy in mice.

ABSTRACT: In the poultry industry, broiler and layer strains are genetically selected for different purposes (e.g., high meat-yield and high egg-production). Genetic selection for productivity can have unintended consequences on the behavioral repertoire of the birds, including aggression. Alongside the increasing societal concern regarding the welfare of animal in agriculture, the number of countries that are advocating the prohibition of using battery cages for laying hens has resulted in the transition and adoption of cage-free or free-range systems. Thus, both broiler and layer chickens are housed in large flocks rather than housed individually in cages. Housing birds in groups increases the opportunity for birds to engage in social behaviors, including aggression, that are used to establish social status. Aggressive interactions are associated with the risk of injury and the potential for a subordinate animal to have unmet needs (e.g., access to feed). The aim of this study was to characterize the relationships among aggressive behavior, neurobiology, and hormones during peck order establishment and social hierarchy stabilization of 2 divergently selected strains (meat- and egg-type chicken). Meat-type strains performed more male on male (P < 0.001), male on female (P < 0.0001), and female on female (P < 0.0001) non-reciprocal aggression behavior (NRA) than egg-type strains. Greater serum testosterone and estradiol concentrations in the weeks after the peck order establishment were observed in meat-type birds compared those in egg-type birds for both males and females (all P < 0.05). Greater (P < 0.05) cellular densities of androgen receptors, but not estrogen receptors, were observed in the hypothalamus of meat-type birds compared to egg-type birds. These findings suggest that greater sex hormone concentrations in the meat-type birds may be a consequence of genetic selection for rapid growth resulting in more sex hormones-induced aggressive behavior.

Repeat breeding is a substantial problem in heifer and cow breeding leading to greater infertility for female dairy herds. The aim of present study was to investigate the impact of corpus luteum (CL) presence and category and the first gonadotropin-releasing hormone (GnRH) administration concurrent with exogenous progesterone (P4) treatment on the largest follicle (LF) size and pregnancy rate (PR) in repeat-breeder crossbred dairy heifers submitted to the fixed-time artificial insemination (AI) protocol. Heifers (n= 243) were synchronised with (+GnRH) or without (–GnRH) first GnRH in the 7-day P4-GnRH-prostaglandin F2α-based programme. Each GnRH group was divided on presence of CL into two groups (+CL and –CL) in a 2 × 2 factorial arrangement. The PR was similar among –GnRH–CL (20.7%), –GnRH+CL (68.8%), +GnRH–CL (30.4%), and +GnRH+CL (68.3%) groups. However, presence of CL in heifers produced a 43.6% increase in PR compared to PR of heifers without CL (odds ratio = 6.550). Heifers bearing large-sized CL had greater large-sized LF on the day of fixed-time AI and PR. Plasma P4 concentration was positively related with CL diameter (r= 0.845; p