Hormone Profiles Around Weaning in Cyclic and Anoestrous Sows

Abstract

Summary Peripheral plasma patterns of LH, cortisol, corticosteroid‐binding globulin (CBG) and β‐endorphin were studied around weaning in sows that resumed cyclicity and those that remained anoestrus after weaning. Average LH concentration in both groups of sows, and basal LH concentration, LH pulses/6h and the sum of LH pulses and peaks/6h in the cyclic sows, increased from the day before weaning to significantly higher (P < 0.05) levels on the days after weaning. Overall, average and basal LH concentrations were higher (P < 0.05) in the sows that resumed cyclicity than in those that remained anoestrus. Cortisol and β‐endorphin concentrations were high before weaning and on the day of weaning in both groups of sows. Cortisol in the cyclic sows, and β‐endorphin in both groups of sows, decreased (P < 0.05) after weaning. CBG levels were unchanged until the second day after weaning when there was an increase (P < 0.05) in both groups of sows. Before and even after weaning cortisol, CBG and β‐endorphin levels tended to be higher in the sows that remained anoestrus compared with those that resumed cyclicity. Findings in the present study show higher levels of cortisol, CBG and β‐endorphin before weaning that persisted even after weaning, and lower LH concentrations around weaning in sows that failed compared with those that resumed oestrous activity.

Influence of feed restriction in primiparous lactating sows on body condition and metabolic parameters

“…Finally, these high concentrations of NEFA could be related to the stress induced by piglet weaning, since stress-related hormones are lipolytic [5]. However, our results did not show any clear increase in cortisol on the day of weaning, in contrast to findings from De Passille et al [15] and Tsuma et al [48].…”

Consequences of variation in weaning-to-estrus interval on reproductive performance of swine females

“…A low suckling stimulus also occurs when there are few or smaller pigs been nursed, aspects observed mainly in procedures as intermittent suckling, splitweaning or utilisation of nurse-sows. These conditions could contribute for the precocious onset of estrus postweaning or lead females to show lactational estrus (Gerritsen et al, 2005), mainly when they receive smaller or wasting piglets (Patterson and Pearce, 1994;Tsuma et al, 1995). In the present study, however, split-weaning was not performed and females used as nurse-sows were excluded from the analysis, showing that these two management procedures could not be the responsible for the precocious onset of estrus after weaning.…”

Physiological mechanisms of ovarian follicular growth in pigs — A review

“…The number of follicles in the cohort depends on the FSH level (Wheaton et al, 1998). However, the most important factor is the pulsatile LH release, which enables follicles to pass the selection process and to begin oestradiol synthesis and secretion (Tsuma et al, 1995). The frequency of LH pulses significantly influences the weaning to oestrus interval (van den Brand et al, 2000).…”

“…Excessive stress at the time of weaning connected, e.g. with dominance-hierarchy fights results in the maintenance of high cortisol level and the reduction of pulsatile LH release (Tsuma et al, 1995). In this case, the disruption of follicular development may be the cause of pathological anoestrus → Fig.…”