Effects of differential patterns of feed intake during lactation, associated metabolic and endocrine changes, and reproductive status after weaning were investigated in 26 primiparous sows suckled by six piglets. Sows were fed to appetite (Group AA; n = 9) from d 1 to 28 of lactation or restricted to 50% from d 22 to 28 (Group AR; n = 9) or from d 1 to 21 (Group RA; n = 8). Sow weight, backfat, and litter weights were recorded weekly. After weaning sows were tested twice daily for onset of estrus and inseminated twice using pooled semen. At d 28 of gestation sows were slaughtered and reproductive tracts were recovered to determine ovulation rate and embryo number. Intensive blood sampling was carried out for 12-h periods on d 21 and before and after weaning on d 28 to characterize changes in plasma LH, FSH, insulin, and IGF-I by RIA. Litter growth rates did not differ among groups. Feedrestricted sows lost more (P < .01) body weight and backfat than those fed to appetite. During periods of feed restriction in AR and RA sows, postprandial insulin, mean IGF-I, and LH pulse frequency were less than in AA sows fed to appetite. All sows exhibited an increase (P < .001) in LH pulsatility in response to weaning. After weaning, no differences were observed in insulin, LH, or FSH, although IGF-I was still lower (P < .05) in AR sows. Weaning-toestrus interval increased in AR and RA sows and ovulation rate was lower (P < .05) than in AA sows. Embryo survival did not differ between RA and AA sows but was lower (P < .01) in AR sows. These results demonstrate that the pattern of metabolic change in the primiparous lactating sow exerts differential effects on fertility after weaning.

Investigations into the biodegradation potential of perfluorooctane sulfonate (PFOS)-precursor candidates have focused on low molecular weight substances (e.g., N-ethyl perfluorooctane sulfonamido ethanol (EtFOSE)) in wastewater treatment plant sludge. Few data are available on PFOS-precursor biodegradation in other environmental compartments, and nothing is known about the stability of high-molecular-weight perfluorooctane sulfonamide-based substances such as the EtFOSE-based phosphate diester (SAmPAP diester) in any environmental compartment. In the present work, the biodegradation potential of SAmPAP diester and EtFOSE by bacteria in marine sediments was evaluated over 120 days at 4 and 25 °C. At both temperatures, EtFOSE was transformed to a suite of products, including N-ethyl perfluorooctane sulfonamidoacetate, perfluorooctane sulfonamidoacetate, N-ethyl perfluorooctane sulfonamide, perfluorooctane sulfonamide, and perfluorooctane sulfonate. Transformation was significantly more rapid at 25 °C (t(1/2) = 44 ± 3.4 days; error represents standard error of the mean (SEM)) compared to 4 °C (t(1/2) = 160 ± 17 days), but much longer than previous biodegradation studies involving EtFOSE in sludge (t(1/2) ∼0.7-4.2 days). In contrast, SAmPAP diester was highly recalcitrant to microbial degradation, with negligible loss and/or associated product formation observed after 120 days at both temperatures, and an estimated half-life of >380 days at 25 °C (estimated using the lower bounds 95% confidence interval of the slope). We hypothesize that the hydrophobicity of SAmPAP diester reduces its bioavailability, thus limiting biotransformation by bacteria in sediments. The lengthy biodegradation half-life of EtFOSE and recalcitrant nature of SAmPAP diester in part explains the elevated concentrations of PFOS-precursors observed in urban marine sediments from Canada, Japan, and the U.S, over a decade after phase-out of their production and commercial application in these countries.

The effect of the timing of nutritional changes during the immediate period after mating on early embryonal survival and of progesterone as a potential mediator of such changes was studied. A total of 82 gilts were initially fed 2.5 kg.gilt-1.d-1 for one estrous cycle before they were inseminated at 16 and 24 h after the onset of estrus (d 0) using fresh, pooled semen. After AI, gilts were randomly allocated to one of the three feeding regimens, normal NRC allowance of 1.5 x maintenance per day from d 1 (Group N1) or d 3 (Group N3) or an allowance of 2 x maintenance from d 1 (Group H1). All gilts were fed on an individual basis. Single blood samples were collected 72 h after first detection of standing estrus. From d 15 onward, all gilts were fed 1.8 kg/d until they were slaughtered on d 28 +/- 3. Total and viable empryonal survival were affected by dietary treatment (P = .044 and .027, respectively), and viable embryonal survival in group N1 was greater than in group H1 (84.7 +/- 4.5 vs 64.5 +/- 7.6%; P < .05). Plasma progesterone was greater in group N1 than in groups N3 and H1 (10.5 +/- 1.0 vs 3.7 +/- .8 and 4.5 +/- .7 ng/mL, respectively; P < .05). The timing of the change in feed allowance after mating is therefore crucial for demonstrating effects of nutrition on embryonal survival in gilts, and progesterone may mediate these effects.

The role of plasma progesterone as a potential mediator of nutritionally induced effects on embryonic survival in gilts was assessed in two experiments. Gilts were individually fed 2.5 kg/d for one estrous cycle and inseminated 12 and 24 h after onset of next estrus (d 0). In Exp. 1, 52 gilts were randomly allocated to either N (1.5 x maintenance feed/d) or H (twice maintenance/d) groups from d 1. In 21 gilts, blood samples were collected on d -1, 0, 1, and 2, and gilts were slaughtered on d 3 to 5. Interval from LH peak to postovulatory progesterone rise was shorter (P = .02) in N (28.8 +/- 2.3 h) than in H (38.6 +/- 3.2 h) gilts, with no difference in rate of rise. Embryonic survival was 86.5 +/- 2.1 and 74.2 +/- 6.2% in N and H gilts, respectively, with a higher variability in Group H (P < .05). In 31 gilts, blood samples were collected 48 and 72 h after estrus onset, and gilts were slaughtered on d 11 and 12. Plasma progesterone concentrations at 72 h were higher (P = .02) in N than in H gilts (14.7 +/- 1.2 vs 10.8 +/- 1.0 ng/mL). Uterine plasmin/trypsin inhibitor concentrations were higher (P = .03) in H than in N gilts, but IGF-I concentrations did not differ. In Exp. 2, gilts were randomly allocated to either H or HP groups on d 1. The HP gilts were given six injections of progesterone (75 mg every 12 h) starting 24 h after estrus onset. Gilts were slaughtered on d 28 +/- 3. Plasma progesterone concentrations at 36, 48, 60, 84, and 108 h after estrus onset were higher (P < .001) in HP than in H gilts. Embryonic survival was also higher (P = .004) in HP (84.8 +/- 2.6%) than in H gilts (70.0 +/- 4.0%). Thus, periovulatory plasma progesterone can be the mediator of nutritionally induced effects on embryonic survival.

No abstract

The environmental occurrence of perfluorooctane sulfonate (PFOS) can arise from its direct use as well as from transformation of precursors ((N-alkyl substituted) perfluorooctane sulfonamides; FOSAMs). Perfluorooctane sulfonamidoethanol-based phosphate (SAmPAP) esters are among numerous potential PFOS-precursors which have not been previously detected in the environment and for which little is known about their stability. Based on their high production volume during the 1970s-2002 and widespread use in food contact paper and packaging, SAmPAP esters may be potentially significant sources of PFOS. Here we report for the first time on the environmental occurrence of SAmPAP diester in marine sediments from an urbanized marine harbor in Vancouver, Canada. SAmPAP diester concentrations in sediment (40-200 pg/g dry weight) were similar to those of PFOS (71-180 pg/g). A significant (p < 0.05) correlation was observed between SAmPAP diester and N-ethyl perfluorooctane sulfonamido acetate (an anticipated degradation product of SAmPAP diester). ∑PFOS-precursor (FOSAM) concentrations in sediment (120-1100 pg/g) were 1.6-24 times greater than those of PFOS in sediment. Although SAmPAP diester was not detected in water, PFOS was observed at concentrations up to 710 pg/L. Among the per- and polyfluoroalkyl substances monitored in the present work, mean log-transformed sediment/water distribution coefficients ranged from 2.3 to 4.3 and increased with number of CF(2) units and N-alkyl substitution (in the case of FOSAMs). Overall, these results highlight the importance of FOSAMs as potentially significant sources of PFOS, in particular for urban marine environments.

The objectives of the present study were 1) to study potential effects of previous nutritional treatment on developmental competence of early fertilized oocytes in vitro; 2) to study responses to insulin treatment during the period of feed restriction in the late luteal phase which has deleterious effects on subsequent fertility; and 3) to establish the metabolic and endocrine status of gilts during treatment and the subsequent periestrous period. Nineteen trios of littermate gilts were subjected to feed restriction during the first (RH) or second (HR) week of the estrous cycle. A second group of HR gilts received injections of long-acting insulin during their period of feed restriction (HR+I). Intensive sampling was performed in a subgroup of 23 animals on d 15 and 16 of the cycle for analyses of endocrine (gonadotropins and steroid hormones) and metabolic (insulin, IGF-I, leptin, total triiodothyronine [T3], and free T3) variables. Gilts were checked for estrus every 6 h, and time of ovulation was monitored by transcutaneous ultrasonography. Surgeries were performed 12 to 20 h after ovulation, and the early-fertilized oocytes recovered were cultured in vitro under standardized conditions. There was no treatment effect on the developmental competence of fertilized oocytes in vitro; however, ovulation rate was increased in HR+I gilts. No effect of treatment was observed on plasma leptin and IGF-I concentrations on d 15 and 16. However, HR+I gilts had higher (P < 0.05) postprandial insulin and lower (P < 0.05) postprandial total and free T3 on d 15. Plasma concentrations of LH, FSH, and progesterone on d 15 and 16 and plasma estradiol concentrations on d 16 were not affected by previous nutritional or insulin treatment. In the periestrous period, plasma concentrations of LH, FSH, and estradiol were higher (P < 0.05) in RH and HR+I, and the rise in plasma progesterone after the LH surge was lower (P < 0.05), than in HR gilts. No effect of treatment was observed on plasma concentrations of metabolic hormones, except on plasma leptin concentrations, which were higher (P < 0.05) at the time of the LH surge in RH gilts. These results suggest that feed restriction during the late luteal phase may have deleterious effects on ovarian function in the periestrous period, which may be counteracted by insulin.

The current experiment was carried out to determine whether exogenous GnRH treatment in primiparous, lactating sows undergoing feed restriction would improve reproductive performance after weaning. Sows were allocated to one of three treatments: AA sows (n = 8) were fed to appetite throughout a 28-d lactation, AR (n = 12) and AR + GnRH (n = 12) sows were fed as AA sows from farrowing to d 21 of lactation, and feed intake was reduced to 50% of the ad libitum intakes from d 22 to 28. The AR + GnRH sows received 800 ng of GnRH i.v. every 6 h from d 22 to 28 of lactation, and AA and AR sows received saline. Sow weight, backfat, and litter weight were recorded weekly. Within 2 d after farrowing, litter size was standardized to 8 to 10. At d 17 of lactation, an indwelling jugular catheter was surgically implanted in each sow. Blood samples were taken for characterization of plasma LH, FSH, insulin, IGF-I, and leptin by RIA at d 21 and before and after weaning on d 28 of lactation. After weaning, all sows were given ad libitum access to feed, checked for onset of standing estrus twice daily with mature vasectomized boars, and inseminated 12 and 24 h after onset of standing estrus with pooled semen from the same fertile boars (3 x 10(9) sperm/AI). After breeding, feed allowance was reduced to NRC (1988) requirements for gestation. At d 28 +/- 3 of gestation, sows were killed and ovulation rate and embryo survival were determined. Restricted sows lost more weight during lactation than AA sows (P < .02). During the period of feed restriction, plasma IGF-I and postprandial insulin and leptin in AR and AR + GnRH sows, and LH pulse frequency in AR sows, were lower than those in AA sows (P < .04). Associations (P < .004) between plasma insulin and leptin and between leptin and mean LH concentrations were established. The LH pulse frequency in AR + GnRH sows did not differ from that in AA sows before weaning. After weaning, maximum, mean, and minimum LH concentrations in the AA and AR sows, and FSH concentrations in AR sows, increased (P < .05) in response to weaning. Paradoxically, GnRH treatment in lactation seemed to suppress the expected LH and FSH responses to weaning. Ovulation rate and embryo survival were not different among the three groups. In conclusion, although exogenous GnRH therapy restored LH secretion in feed-restricted sows, it did not improve overall reproductive performance.