We investigated changes in peripheral concentrations of inhibin A, total inhibin, steroids, and gonadotropins throughout the intact estrous cycle of the sow in relation to ovarian changes determined by daily transrectal ultrasonography. All visible follicles of 3 mm or more in diameter were classified as small (R3 and !6 mm) or large (R6 mm). Follicular recruitment was identified in two periods of the cycle: one from the late luteal to the follicular phase, characterized by an increase in the number of small follicles followed by the appearance of large follicles; and another during the early luteal phase, consisting only of increased numbers of small follicles. Plasma concentrations of inhibin A increased (P!0.05), coinciding with the two periods of follicle emergence. Estradiol (E 2 ) levels increased (P!0.05) during the follicular phase, but not during the early luteal phase. An inverse relationship (P!0.01) between the patterns of inhibin and FSH concentrations was noted around the two periods of follicle emergence, but there was no relationship (PR0.1) between the patterns of plasma E 2 and FSH during the early luteal phase. In conclusion, measurement of plasma inhibin A levels combined with ultrasonographic examination of the ovaries revealed two periods of synchronous follicular growth during the sow's estrous cycle. The results strongly suggest that inhibin A functions as a negative feedback regulator of FSH secretion throughout the estrous cycle, whereas E 2 appears to influence FSH secretion only during the follicular phase.Reproduction (2010) 139 153-161

Abstract. The aims of this study were to determine whether a single treatment of estradiol dipropionate (EDP) could induce pseudopregnancy in gilts and to determine the effectiveness of PGF2α treatment on estrus synchronization in EDP-induced pseudopregnant gilts. In experiment 1, gilts were treated with 20 mg of EDP (n=11) or vehicle (n=5) on Day 12 (Day 0=onset of estrus). Establishment of pseudopregnancy was defined as a lack of estrus and maintenance of the plasma progesterone concentration above 1 ng/ml between Days 12 and 36. Nine of 11 gilts (82%) treated with EDP became pseudopregnant. The plasma estradiol-17β level was significantly higher in the EDP-treated gilts than in the control gilts until Day 29. In experiment 2, PGF2α was administered twice with a 24-h interval from Day 36 in pseudopregnant gilts (n=6) or Day 10 in cyclic gilts (control; n=5). Estrus after PGF2α treatment was observed in 83% of the pseudopregnant gilts. The interval from the day of the first PGF2α treatment to the onset of estrus and the peak of the LH surge was significantly shorter in the pseudopregnant gilts than in the control gilts. In experiment 3, six pseudopregnant gilts were bred by artificial insemination at the estrus after PGF2α treatment. The farrowing rate and average litter size did not differ between the PGF2α-treated pseudopregnant and cyclic gilts. These results indicate that a single treatment of EDP on Day 12 of the estrous cycle can induce pseudopregnancy in pigs and that a convenient protocol for administering PGF2α to EDP-induced pseudopregnant pigs is available for estrus synchronization programs in cyclic pigs. Key words: Estradiol dipropionate, Estrus control, Pig, Pseudopregnancy (J. Reprod. Dev. 56: [421][422][423][424][425][426][427] 2010) t is desirable to have female pigs in estrus at certain times to provide maximum use of intensive pork production facilities. Application of estrus synchronization programs enhances economic performance in the swine industry by reducing the labor required to detect estrus, facilitating the use of artificial insemination (AI) and assisting in batch farrowing. Therefore, being able to control the time of estrus in a breeding herd results in decreased reproductive efforts and costs.Artificially shortening or extending the luteal phase is important for control of the interestrous interval in cyclic animals. The corpus luteum (CL) of the cycling pig generally exhibits resistance to prostaglandin F2α (PGF2α)-induced luteolysis prior to Day 12 of the estrous cycle [1][2][3]. Consequently, multiple administrations of PGF2α in the early luteal phase are required to induce luteolysis of the functional CL and shorten the estrous cycle [2,3]. In contrast to the CL before Day 12 of the estrous cycle, the CL of the pregnant pig easily reacts to exogenous administration of PGF2α [4,5], and prompt estrus can be induced between 4 and 7 days after PGF2α treatment; however, exogenous administration of PGF2α is associated with abortion in pregnant pigs [4,6].In pigs, two phases of ...

Although our previous report demonstrated that adiponectin and AdipoR1 gene expressions changed among different lactation stages in the bovine mammary gland, its in vivo kinetics remain unclear in ruminant animals. In this study, we investigated the changes in circulating concentrations of adiponectin, as well as other metabolic hormones and metabolites, (i) during the periparturient period and (ii) among different lactation stages, in Holstein dairy cows. In experiment 1, serum adiponectin concentrations increased after parturition. Serum insulin concentrations were lower in the postpartum than prepartum period, whereas serum growth hormone (GH) concentrations increased in the postpartum period. Serum nonesterified fatty acids (NEFA) levels were increased during the postpartum period and were dependent on the parity. In experiment 2, there was no significant difference in plasma adiponectin concentrations among lactational stages. Plasma insulin concentrations tended to be lower in early lactation while plasma GH levels tended to be higher. Plasma NEFA concentrations were significantly lower in mid-and late-lactation stages than non-lactation stages. These findings indicate that elevation of serum adiponectin might be involved in energy metabolism just around parturition, and might exert its action through regulation of receptor expression levels in target tissues in each lactational stage in Holstein dairy cows. Kadowaki T.2001. The fat-derived hormone adiponectin reverses insulin resistance associated with both lipoatrophy and obesity. Nature Medicine 7, 941-946. ADIPONECTIN SECRETION CHANGES IN DAIRY COWS 795

ABSTRACT. To investigate the roles of mammary PTHrP in calcium uptake and/or release in the mammary gland of cows, plasma PTHrP and Ca levels, and their arterial-venous differences were examined in a Jersey cow during the periparturient period. Levels of Ca in both abdominal aorta and abdominal subcutaneous vein blood slightly decreased around the parturition and at 24 days after the parturition, however, no remarkable arterial-venous differences were observed. Plasma PTHrP levels in both arterial and venous samples were below the detection limit (0.57 pmol/l) during the experimental period. Milk PTHrP and Ca levels were measured in 9 Holstein dairy cows. Although plasma PTHrP levels in all arterial and venous samples were also below the detection limit, milk PTHrP and Ca levels were remarkably high, ranging from 14,900 pmol/l to 41,200 pmol/l and from 772 mg/l to 1,200 mg/l, respectively. In addition, a significant positive correlation (P<0.01) was observed between milk PTHrP and Ca levels. These results suggested that mammary PTHrP is closely related to Ca concentration in the milk.

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