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This study was conducted to determine whether exogenous melatonin affected gilt fertility when there were different housing temperature and lighting conditions.
Methods: Prepubertal gilts (n = 72) were fed (5 mg/day) or not fed (control) melatonin while housed in rooms where temperatures (31.0 ± 1 °C) and daily lighting (240 lx) duration differed: 8, 16, or 24 hours in winter and summer replicates. Gilts were moved into rooms (day 1) and administered PG600 on day 6. Gilts detected in estrus were inseminated and slaughtered on day 33 of gestation to determine pregnancy and litter responses.
Results: There was no treatment x room effect on estrus (77.8 %), follicle sizes, or number of corpora lutea, but melatonin-treated gilts had a longer estrous duration (2.0 days) than gilts of the control (1.7 days) group. Pregnancy rate (92.6 %) and embryo number (13.5) were not affected by treatment or room conditions. There was a treatment x room effect, however, with embryo survival being less by ∼23 % in gilts of the control-24 hours than control-16 hours, melatonin-8 hours, and melatonin-24 hours groups. In the summer replicate, there were also fewer large follicles, a lesser estrous detection percentage, viable embryos, and embryo survival rate than during the winter.
Conclusion: Overall, melatonin treatment had positive effects on estrous duration and embryo survival, especially in the summer when there were varying lighting regimens and room temperatures in which gilts were housed.
Arend LS, Knox RV. Fertility responses of melatonin-treated gilts before and during the follicular and early luteal phases when there are different temperatures and lighting conditions in the housing area. Animal Reproduction Science, 2021; 230: 106769. https://doi.org/10.1016/j.anireprosci.2021.106769.