Impact of Oxytocin Administration on Milk Quality, Reproductive Performance and Residual Effects in Dairy Animals – A Review

Abstract

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Factors affecting postpartum ovarian activity of goats in tropical semi-arid region

“…In addition, the oxytocin causes contraction of the uterus by myometrial contractions stimulating the endogenous release of PGF2α that in the first postpartum days acts by accelerating the expulsion of lochia and causing an earlier uterine involution (16). Faraz et al (2020) reported some studies that found no deleterious effects of oxytocin on the reproductive health in females due to the oxytocin had a short life span of about 2.5 minutes, however, in this same review it is mentioned that goats increase the concentration of oxytocin at the beginning of milking and concomitantly with the increase in prolactin; it is assumed that in order for lactogenesis to be maintained, milk must be removed from the mammary gland. The sensorial stimulus of teat suction by kids stimulates the production of prolactin, which inhibits the release of dopamine and GnRH-associated peptides.…”

“…The first ovarian cycle after an anoestrus period in goats is not preceded by the usual oestrous activity and both the duration and concentration of progesterone secretion by the corpus luteum are generally lower than normal (17). In ewes, the first two ovulations are of poor quality, due to the low pulsatility of FSH, due to the fact that the small follicles have a low number of granulosa cells, which produce low levels of estradiol, which may explain the possible absence of sexual receptivity prior to the first ovulation (33), known as "silent ovulation" (59).…”

“…Goats are seasonal polyestrics, but when reared in tropical regions they may exhibit reproductive activity throughout the year (17). However, during the postpartum period, the ovaries are unable to promote follicles to preovulatory status because of inhibition of the hypothalamic-pituitary axis resulting in a period of anoestrus (puerperal or postpartum) until the goats exhibit oestrous behaviour (46).…”

“…During lactation, the influence of prolactin and endogenous opioids, such as β-endorphins, which inhibit the secretion of GnRH as well as FSH-and LH-releasing hormones (FSH-RH and LH-RH), reduces the frequency of LH pulses (13,25,44,76). This reduction in the pulses of LH induces small corpora lutea, which in turn reduce the release of progesterone to levels that may not be enough to maintain gestation (17). The LH release is influenced by body condition, which will be discussed in more detail later.…”

“…Several authors have reported longer postpartum anoestrus in goats during the dry season when compared to animals giving birth during the rainy season (17,37). During the dry season, animals grazing on natural pasture can experience a decline in LH secretion due to the severe reduction in feed availability (figure 2 However, researchers in the Brazilian semi-arid region are still searching for further explanations as to how the rainy season has a positive effect on goats' ovarian activity (52).…”