AUTHOR=Ratchamak Ruthaiporn , Thananurak Pachara , Boonkum Wuttigrai , Semaming Yoswaris , Chankitisakul Vibuntita 

TITLE=The Melatonin Treatment Improves the Ovarian Responses After Superstimulation in Thai-Holstein Crossbreeds Under Heat Stress Conditions

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.888039

DOI=10.3389/fvets.2022.888039

ISSN=2297-1769

ABSTRACT=<p>The effect of heat stress with melatonin treatment on the superovulatory responses and embryo characteristics in Thai-Holstein crossbreeds under heat stress conditions was examined. Six non-lactating cows (replication = 4; <italic>n</italic> = 24) were assigned to one of 2 treatments in double cross-over design. All cows were superstimulated with traditional treatment. Melatonin group (<italic>n</italic> = 12): cows received intramuscularly injection 18 mg/50 kg. simultaneously with GnRH injection, while those in the control group (<italic>n</italic> = 12) received none. Bloods samples were taken to determine lipid peroxidation (MDA) and the activity of the antioxidant enzymes (superoxide dismutase; SOD). The experiment was conducted from April to September, which determined severe heat stress (the mean temperature-humidity index above 77). The results revealed that numbers of large follicles and corpora lutea were higher in the melatonin group than in the control group (<italic>p</italic> &lt; 0.01). Numbers of recovered ova/embryos, fertilized ova, and transferable embryos were higher in the melatonin group (<italic>p</italic> &lt; 0.01); meanwhile, more degenerated embryos were found in the control group (<italic>p</italic> &lt; 0.01). Increased activity of the antioxidant enzymes SOD after melatonin administration decreased MDA levels (<italic>p</italic> &lt; 0.05). In summary, melatonin administration benefited the ovarian response and embryo quality in superstimulated Thai-Holstein crossbreed affected by heat stress.</p>