Effects of prenatal and postnatal melatonin supplementation on overall performance, male reproductive performance, and testicular hemodynamics in beef cattle

Authors: REID, DANA - Mississippi State University; Geary, Thomas; Zezeski, Abby; Waterman, Richard; VAN EMON, MEGAN - Montana State University; MESSMAN, RILEY - Mississippi State University; BURNETT, DERRIS - Mississippi State University; LEMLEY, CALEB - Mississippi State University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2023
Publication Date: 4/13/2023
Citation: Reid, D.S., Geary, T.W., Zezeski, A.L., Waterman, R.C., Van Emon, M.L., Messman, R.D., Burnett, D.D., Lemley, C.O. 2023. Effects of prenatal and postnatal melatonin supplementation on overall performance, male reproductive performance, and testicular hemodynamics in beef cattle. Journal of Animal Science. 101. Article skad111. https://doi.org/10.1093/jas/skad111.
DOI: https://doi.org/10.1093/jas/skad111

Interpretive Summary: Previous studies have used melatonin ear implants in cows during the last 90 days pregnancy. These studies were conducted in cows that calved during the Fall. Researchers reported greater blood flow to the uterus of cows without affecting calf birth weight. However, calf weights at weaning were greater in calves born to melatonin treated cows compared to control cows. The current study evaluated calves born to cows that received melatonin during the last 90 days of pregnancy and/or received melatonin after birth. The current study also used cows that calved in the Spring. Calf performance and weight at weaning were not affected by maternal or postnatal melatonin supplementation. However, cow milk yield and fat percent were decreased in the melatonin supplemented cows. Melatonin treatment did not affect fertility measures of bull calves at one year of age. Cow blood levels of melatonin were not different between treatment groups. Calves that received melatonin treatment after birth had greater blood levels of melatonin. In this study, dams were implanted in winter months, whereas calves were implanted in the spring months. Seasonal differences involving day length and temperature may have affected responses to melatonin treatment among cows.

Technical Abstract: Melatonin has been documented to alleviate compromised pregnancies and enhance livestock performance traits. The objective of this study was to determine the effect of prenatal and postnatal melatonin supplementation on overall calf performance and dam milking traits in relation to calves, molecular factors involved in growth and metabolism of calves, along with testicular physiology and fertility traits in subsequent bulls. At day 190, 220 and 250 of gestation, dams (n = 60) were administered either 2 subdermal ear melatonin implants (preMEL) or no implants (preCON). After parturition, birth weights were recorded and calves were blocked based on prenatal treatment and sex. Calves received either melatonin implants (posMEL) or none (posCON) on day 0, 30, and 60 of age. At day 60 of lactation, a subset of dams (n= 32) were selected based on age, weight and calf sex for milk collection and analysis. At weaning, (day 210 postnatally) calf weight, morphometric data, liver samples, and loin samples were collected. At 12 months of age, bull (n = 30) scrotal circumference, scrotal temperature, and testicular artery measurements were recorded. Milk yield and fat percent from dams tended to decrease in the preMEL group (P < 0.07) compared with preCON group. Prenatal melatonin administration did not affect (P = 0.95) calf birth weight and similarly calf weaning weight was unaffected (P < 0.10) by prenatal or postnatal melatonin supplementation. Blood analysis demonstrated that plasma concentrations of melatonin were not different (P = 0.12) in dams; however, an increase (P < 0.001) in plasma concentrations of melatonin was observed in posMEL versus posCON calves. A tendency (P < 0.10) for decreased MYF5 and MYOD1 expression in loin muscle was observed in the posMEL calves. Prenatal and postnatal melatonin administration did not affect subsequent bull scrotal measurements or testicular hemodynamics (P = 0.14). Administering supplemental melatonin via implants during the prenatal and postnatal phase did not alter performance characteristics in offspring. In this study, dams were implanted in winter months, whereas calves were implanted in the spring months. Seasonal differences involving photoperiod and ambient temperature might have attributed to a lack of differences in melatonin levels during the prenatal phase. In the postnatal period, the level of developmental plasticity appears to be too low for melatonin properties to be effective.