The release of reproductive hormones in the hypothalamic–pituitary–gonadal (HPG) axis is regulated by its upstream regulator, kisspeptin, and influenced by external stresses, including heat stress. Since the effect of heat stress (summer infertility) on hypothalamic kisspeptin expression in domestic sows is not yet understood, the present study attempted to identify changes in kisspeptin expression in different seasons (summer and spring). The high atmospheric temperature in summer decreased the pregnancy rate and litter size and increased stress-related hormones as a chronic stressor to domestic sows. The hypothalamic kisspeptin expression in summer was decreased regardless of the estrus phase and negatively correlated with atmospheric temperature, indicating that high temperature decreased kisspeptin. When the activity of hypothalamic kisspeptin neurons in the follicular phase was assessed using c-Fos staining, a decreased number of kisspeptin neurons coexpressing c-Fos was observed in domestic sows in summer. Accordingly, lower expression of kisspeptin induced decreased levels of HPG axis-related reproductive hormones, such as gonadotropins and estrogen, and fewer large ovarian follicles. In conclusion, the present study demonstrated that reduced kisspeptin expression and its neuronal activity in the hypothalamus under heat stress in summer induced downregulation of the HPG axis and caused summer infertility in domestic sows.

Objective: Pregnancy in cattle after embryo transfer (ET) is influenced by several factors, including embryo quality. Therefore, preparing high-quality embryos with the greatest developmental potential is essential for achieving a successful pregnancy after ET. Meanwhile, blastocysts produced by in vitro fertilization (IVF) procedure have different developmental speed during in vitro culture (IVC) and they exhibited different competence in the establishment of pregnancy.Methods: This study aimed to identify the comparative features of early-, mid-, and late-developing bovine IVF blastocysts, when they first appeared at Day 7, 8, and 9 during IVC, respectively. In addition, the correlations between their molecular features and pregnancy ability were analyzed.Results: The results showed no difference in the morphological characteristics, including total cell count and diameter, between the Day 7, 8, and 9 blastocysts. However, the pregnancy rate post-ET was significantly different between the groups at 51.7%, 36.7%, and 17.8% for Day 7, 8, and 9 blastocysts, respectively. During early embryo development, late-developing blastocysts demonstrated a reduced cell count in the inner cell mass and decreased expression of the early embryo developmental genes (Oct4 and Sox2) compared with the early- and mid-developing blastocysts. In addition, the number of apoptotic cells and apoptosis-related gene expression (increased Bax and decreased Bcl2) gradually elevated from the Day 7 to Day 9 blastocysts. However, there was no difference in mitochondrial activity and mitochondria-relevant gene expression (Tfam and Cox1) between the groups. Correlation analysis identified a significantly negative correlation between the pregnancy rate and the blastocysts’ degree of apoptosis, indicating that the low pregnancy ability of late-developing blastocysts was mainly caused by increased apoptosis.Conclusion: This study’s results may contribute to the field of animal biotechnology by assisting in establishing an improved strategy for bovine ET with IVF embryos.

Kim D, et al. J Vet Sci. 2022 Sep;23:e81. https://doi.org/10.4142/jvs.22105

The present study was performed to survey the dominant tick populations and molecularly determine the pathogenic agents of anaplasmosis in ticks from Gyeongsang, Republic of Korea. A total of 3825 questing ticks were collected by the flagging method from 12 sites near animal farms in Gyeongsang from March to October 2021. A molecular genomic study was performed with ticks stored in 70% ethanol to detect Anaplasma genes by the previously described method. The monthly incidence of ticks varied by developmental stages, i.e., nymphs, adults, and larvae, and each of their populations peaked in May, March, and October, respectively. The predominant tick species were Haemaphysalis longicornis, Haemaphysalis sp., Haemaphysalis flava, Ixodes nipponensis, and Amblyomma testudinarium in order. To determine the Anaplasma infection rate, collected ticks were pooled into 395 groups. The minimum infection rate (MIR) of Anaplasma was 0.7% (27 pools). That of A. phagocytophilum was highest (23 pools, MIR 0.6%), followed by A. phagocytophilum-like Anaplasma spp. clade B (2 pools, MIR 0.1%), A. bovis (1 pool, MIR 0.1%), and A. capra (1 pool, MIR 0.1%), respectively. In this study, five species of ticks, including unidentified Haemaphysalis species, were collected in 12 survey sites in Gyeongsang, but their prevalence was somewhat different according to the tick species and survey sites. Further, the incidence rate (6.8%) of 4 Anaplasma spp. was not as high in tick pools. However, the results of this study may offer a basis for future epidemiological research and risk assessment of tick-borne diseases.

Jong-Chan Hwang, Hwan-Deuk Kim, Byung-Joon Park, Ryoung-Hoon Jeon, Su-Min Baek, Seoung-Woo Lee, Min Jang, Seul-Gi Bae, Sung-Ho Yun, Jin-Kyu Park, Young-Sam Kwon, Seung-Joon Kim and Won-Jae Lee. Journal of Animal Reproduction and Biotechnology 2021;36:9-16. https://doi.org/10.12750/JARB.36.1.9

Dongyub Kim, Hwan-Deuk Kim, Youngmin Son, Sungho Kim, Min Jang, Seul-Gi Bae, Sung-Ho Yun, Seung-Joon Kim and Won-Jae Lee. Journal of Animal Reproduction and Biotechnology 2021;36:261-9. https://doi.org/10.12750/JARB.36.4.261