Ovarian follicular changes after weaning in sows

Abstract

Three experiments investigated ovarian follicular development in sows whose litters were weaned at 28 to 31 d of lactation. Unilateral ovariectomy near the time of weaning was used to assess early follicular characteristics and to identify those sows that would not return to estrus within 10 d after weaning. This allowed segregation of and exclusion from the study those sows that had a prolonged interval from weaning to first estrus. In Exp. 1, 82 and 72% of the large follicles that were marked at 48 or 72 h after weaning (10 sows per time point) were subsequently identified as corpora lutea. In Exp. 2, sows (seven to nine per time point) were unilaterally ovariectomized at 0, 6, 12, 18, 24, or 48 h after weaning, and follicular fluid was evaluated for changes in steroid concentrations. Progesterone concentrations in fluid from medium-sized (4 to 6 mm) follicles increased by 6 h after weaning and then declined through 24 h concomitant with increases in testosterone and estradiol. For Exp. 3, follicular fluid and granulosa cells from individual follicles were obtained from sows (seven to nine per time point) at 0, 6, and 24 h after weaning. In follicular fluid, insulin-like growth factor I (IGF-I) concentrations were not correlated (P greater than .05) with concentrations of progesterone, testosterone, or estradiol, or with granulosa cell production of estradiol during culture in androstenedione-supplemented medium.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of food intake during lactation and post weaning on the reproductive performance and hormone and metabolite concentrations of primiparous sows

“…Consistent with previous reports in gilts, concentrations of IGF-1 and oestradiol were lower in follicular fluid in small than in medium follicles (Echternkamp et al, 1994). A previous study with pluriparous weaned sows reported that follicular fluid concentrations of IGF-1 did not change from 0 to 48 h after weaning while follicular fluid oestradiol concentrations increased (Killen et al, 1992). Thus, the present and previous (Killen et al, 1992) studies suggest that IGF-1 concentrations at weaning seem to be sufficient to support increases in oestradiol with time after weaning.…”

“…A previous study with pluriparous weaned sows reported that follicular fluid concentrations of IGF-1 did not change from 0 to 48 h after weaning while follicular fluid oestradiol concentrations increased (Killen et al, 1992). Thus, the present and previous (Killen et al, 1992) studies suggest that IGF-1 concentrations at weaning seem to be sufficient to support increases in oestradiol with time after weaning. Weldon, W. C, Lewis, A. J., Louis, G. F., Kovar, J. L., Giesemann, M. A. and Miller, P. S. 1994a.…”

Effect of castration on serum concentrations of gonadal hormones, insulin-like growth factor-I and its binding proteins in male pigs

“…It circulates in blood bound to specific binding proteins (IGFBP) of approximately 18 and 43 kDa (Smith, 1984). IGF-I and IGFBPs in serum have been studied in gilts and sows under various experimental conditions including ovariectomy (Barb et al, 1992;Howard and Ford, 1992;Killen et al, 1992;Cox et al, 1994;Klindt et al, 1994). In boars, castration led to a fall in serum GH and IGF-I levels (Arbona et al, 1989;Dubreuil et al, 1989;Louveau et al, 1991).…”

Factors associated with puberty onset and reproductive performance of gilts

“…Several studies have reported similar return to estrus interval values for sows (Deckert et al, 1997;Killen et al, 1992). A sow's wean-to-estrus interval is variable and can be influenced by a variety of factors such as parity, season, nutrition, and boar exposure (Dial et al, 1992).…”