Effects of feeding melatonin during proestrus and early gestation to gilts and parity 1 sows to minimize effects of seasonal infertility1

Abstract

This study tested whether supplemental melatonin given to mimic the extended nighttime melatonin pattern observed in the higher fertility winter season could minimize infertility during summer and fall in swine. Exogenous melatonin was fed during periods coinciding with follicle selection, corpus luteum formation, pregnancy recognition, and early embryo survival. Experiments were conducted at a commercial farm in 12 sequential replicates. In Exp. 1a, mature gilts (n = 420) that had expressed a second estrus were assigned by weight to receive once daily oral Melatonin (MEL, 3 mg) or Control (CON, placebo) at 1400 h for 3 wk starting before insemination at third estrus. In Exp. 1b, parity 1 sows (n = 470) were randomly assigned by lactation length to receive MEL or CON for 3 wk, starting 2 d before weaning. Follicles, estrus, pregnancy, and farrowing data were analyzed for the main effects of treatment, season (4-wk periods), and their interaction. Environmental measures were also analyzed for reproductive responses. In Exp. 1a, there was no effect (P > 0.10) of MEL on age at third estrus (203 d), follicle size after 7 d of treatment (5.0 mm), estrous cycle length (22.6 d), return to service (9.2%), farrowing rate (FR, 80.0%), or total born pigs (TB, 13.6). However, there was an effect of season (P = 0.03) on number of follicles and on gilts expressing estrus within 23 d of the previous estrus (P < 0.005). In Exp. 1b, there was no effect of MEL (P > 0.10) on follicle measures, wean to estrous interval, FR (84.0%), or TB (13.0). But MEL (73.5%) reduced (P = 0.03) estrous expression within 7 d of weaning compared with CON (82.0%) and season (P = 0.001) decreased FR by ~14.0% during mid summer. Also, gilts and parity 1 sows exposed to low light intensity (<45 lx) during breeding had reduced conception (−8%) and farrowing (−15%) rates, compared with higher light intensity. Similarly, high temperatures (>25 °C) during breeding also reduced gilt conception rates by 7%. Although there was clear evidence of seasonal fertility failures in gilts and sows, MEL treatment did not improve fertility in gilts and reduced estrus in parity 1 sows. It is possible that differences in lighting and thermal environments before breeding could explain the differential response to MEL in sows and gilts.

Effects of Melatonin Supplementation during Pregnancy on Reproductive Performance, Maternal–Placental–Fetal Redox Status, and Placental Mitochondrial Function in a Sow Model

“…In this study, dietary supplementation with MT significantly elevated serum melatonin concentrations at all time points tested, even prior to the onset of feeding. The patterns of circulating MT in pigs have been described as unchanging, irregular, or nocturnal [ 40 , 41 , 42 ]. The inconsistency in the MT profiles could be related to differences in assay methodology, geographical location of the study, lighting regimen, acclimation period, and method for administration of MT [ 42 , 43 , 44 , 45 ].…”

“…The patterns of circulating MT in pigs have been described as unchanging, irregular, or nocturnal [ 40 , 41 , 42 ]. The inconsistency in the MT profiles could be related to differences in assay methodology, geographical location of the study, lighting regimen, acclimation period, and method for administration of MT [ 42 , 43 , 44 , 45 ]. So far as we know, there are no published reports from sequential blood sampling in pregnant sows fed such a high dose of MT to compare with our study.…”

“…In domestic gilts, oral application of 1 mg MT increased plasma MT concentrations within 30 min and that these remained high for at least 8 h [ 46 ]. In addition, oral application of MT (3 mg/d) at 15:00 h showed an elevated peak of melatonin ~6 h after lights off, and the overall patterns for MT in circulation appeared episodic at 3–6 h intervals while lights were on [ 42 ]. Furthermore, in this study, no statistically significant differences of MT supplementation on serum ALT, AST, and γ-GGT concentrations are an indication that the treatments have no obvious effect on liver function.…”

Follicle development in pigs: State of the art

“…Data suggesting HPX involvement are inconsistent with respect to differential response to E2 on FSH/LH or estrus (Cox et al, 1987; Kennaway et al, 2015). Nevertheless, effects of season or heat stress have been noted on follicles and estrus (Arend et al, 2019; Lopes et al, 2014) or on progesterone production in vivo (Bertoldo et al, 2011) or in vitro (Sirotkin, 2010). Photoperiod effects on follicles are undefined and perhaps may result through effects on the HPX (Peltoniemi & Virolainen, 2006), although Kermabon et al (1995) did not detect changes in FSH/LH by season.…”

Releasing Hormone and Vitamin Efficiency in the Treatment of Obstetric and Gynecological Pathologies in Breeding Sows

“…Sows during birth and the postpartum period are particularly susceptible to adverse exogenous and endogenous factors [3]. Frequent postpartum genital diseases eventually cause infertility in sows and insufficient quality and quantity of young animals [4].…”