Chronic Administration of Anacetrapib Is Associated With Accumulation in Adipose and Slow Elimination.

Anacetrapib is a novel cholesteryl-ester transfer protein (CETP) inhibitor in late-stage clinical development, shown in preceding clinical trials to have residual pharmacological activity after prolonged washout after chronic dosing. Preclinical findings suggest that white adipose tissue is a potential depot and that accumulation into adipose tissue governs the long-term kinetics of anacetrapib in mice. A phase I study performed to test this hypothesis in humans revealed that plasma exposure was correlated with fat content in food administered with the drug. Plasma concentrations of anacetrapib seemed to reach plateau faster than adipose concentrations. Anacetrapib continued to accumulate in adipose during the treatment period despite apparent plateau in plasma with only minimal decline in adipose levels up to 1 year postdose. Because of its high lipophilicity, anacetrapib partitions into adipose tissue, this likely forms a drug reservoir that, in turn, contributes to the long residence time of the drug in plasma.

Expression of insulin-like growth factor-binding protein-2 and -3 messenger ribonucleic acid in the porcine ovary: localization and physiological changes.

Insulin-like growth factor-binding protein (IGFBP)-2 and -3 are the most prevalent IGFBPs in porcine follicular fluid, as determined on ligand blots, but little is known about the localization and regulation of their synthesis in vivo. This study was designed to investigate the localization and cyclic regulation of the mRNA for these two IGFBPs in the porcine ovary, RNA was extracted from whole ovaries morphologically classified as immature, preovulatory, and luteal. Northern hybridization analysis of this RNA showed no significant difference in the expression of IGFBP-2 mRNA in these ovaries (OD for preovulatory, luteal, and immature ovaries, 0.076 +/- 0.01, 0.071 +/- 0.01, and 0.10 +/- 0.008/micrograms RNA, respectively). IGFBP-3 mRNA was not different in immature and preovulatory ovaries, but was 10-fold greater (P less than 0.025) in luteal ovaries. Northern analysis of RNA extracted from ovaries also showed no significant change in IGFBP-2 mRNA on days (d) 11, 16, and 21 of the estrous cycle. IGFBP-3 mRNA tended to decrease between d11-16 with the onset of luteal regression and was significantly decreased in d21 preovulatory ovaries to 22% of the values in d11 ovaries. Granulosa, thecal, and luteal cells were also analyzed for IGFBP mRNA. IGFBP-2 mRNA was most abundant in granulosa cells, lower in thecal cells, and lowest in luteal cells. No IGFBP-3 mRNA could be detected in granulosa cells, and luteal cells expressed 15- to 63-fold greater levels than thecal cells. These results show that IGFBP-2 and -3 mRNAs are expressed in specific ovarian cell types and that their expression appears to be independently regulated during the reproductive cycle. This provides further evidence for the importance of these proteins as paracrine/autocrine regulators of ovarian function.

Estrone concentration in sow milk during and after parturition.

Colostrum and milk samples were obtained from five Yorkshire gilts through manual expression of glands at the onset of parturition; at 1, 2, 4 and 8 h after birth of the first piglet and at 8-h intervals thereafter until 96 h. Oxytocin (30 units) was used to stimulate milk ejection for all samples except during parturition. Samples were frozen until subjected to a validated radioimmunoassay for estrone (E1). In a preliminary study no differences existed in concentrations of E1 among various glands. Therefore, mean of values obtained from three randomly selected glands was used for analysis in the main trial. Concentration of E1 at birth averaged 13.6 +/- 1.78 ng/ml (X +/- SE), and decreased to 6.05 +/- .80, 3.12 +/- .60, 1.42 +/- .30, .69 +/- .20 and .33 +/- .92 ng/ml at 4, 8, 16, 32 and 96 h, respectively. The postpartum decrease in the concentration of E1 in the milk is most likely due to the loss of the placental source.

Relationship of estrone and prolactin with growth and survival of piglets to 35 d of age.

The relationship between estrogen or prolactin (Prl) status of pigs at birth and subsequent performance was examined in ten (Study 1) or seven (Study II) Yorkshire litters. In both studies, piglets were bled (3 ml) from the suborbital sinus at birth, and then hourly for 12 h. Hematocrit (Hct) and concentrations of plasma protein (PP) and estrone (E1) were determined on all samples. Concentrations of Prl were determined only in samples at birth. Weights at 3 and 5 wk of age as well as percent survival to 5 wk were obtained. Mean concentrations of E1 and Prl in piglets at birth were 6.97 +/- 44 ng/ml and 9.12 +/- .32 ng/ml, respectively. A decrease in E1 occurred over the first few hours after birth. Hematocrit values also decreased postnatally, whereas concentrations of PP increased. Sex of neonate did not affect any of the blood characteristics studied. Correlations between E1, PP, Hct and Prl at birth and body weights at birth, 3 and 5 wk were nonsignificant. However, piglets with higher Prl values at birth showed a greater survival rate. In Study II, half of the piglets in each litter were implanted at birth with silicone rubber implants containing estradiol-17 beta. Estrone concentrations were significantly higher in implanted piglets than in controls over the subsequent 12-h period, but Hct and PP values were not affected by treatment, suggesting that treated piglets did not consume more colostrum.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of frequency of administration of exogenous porcine growth hormone on growth and carcass traits and ovarian function of prepubertal gilts.

Three experiments were conducted to examine relationships among dose and frequency of administration of exogenous porcine growth hormone (pGH) on growth traits and ovarian function of prepubertal gilts. In Exp. 1, gilts were treated with 0 or 5 mg of pGH daily for 42 d or 5 mg of pGH daily on alternate weeks over a 42-d period. In Exp. 2, gilts were treated with 0, 2.5, or 5 mg of pGH daily for 31 d or daily on alternate weeks for 31 d. In Exp. 3, gilts received 5 mg of pGH daily on either wk 1, 3, and 5 or wk 2, 4, and 6 during a 42-d period. In all experiments, ADG increased dramatically and feed efficiency improved markedly during treatment with pGH, and both traits declined rapidly during periods when treatment was withdrawn. Gilts treated with pGH daily on alternate weeks tended to be more similar (P greater than .05) to control gilts for growth rate, feed efficiency, and carcass measurements than to gilts that received continuous daily administration of pGH during the entire duration of the experiments. Increased concentrations of estradiol and insulin-like growth factor (IGF)-I in follicular fluid and serum, decreased concentrations of IGF-II in follicular fluid, and increased weights of ovaries were evident as both dose and frequency of exogenous pGH administration increased. Therefore, gilts are extremely sensitive to administration and withdrawal of exogenous pGH during the finishing phase of the production cycle and can respond within 7 d to changes in exogenous pGH treatment regimens. Alternate weekly administration of exogenous pGH in vivo may improve follicular function, as indicated by relationships among IGF-I and IGF-II, estradiol, and progesterone, but fails to improve overall growth and carcass traits compared with controls.

Effect of treatment with and subsequent withdrawal of exogenous porcine somatotropin on growth and reproductive characteristics of gilts.

Two experiments were conducted to examine responses of gilts to treatment with and withdrawal of exogenous porcine somatotropin (PST). In Exp. 1, 36 prepubertal gilts (79.7 +/- .9 kg; 159.1 +/- .7 d) were allotted randomly to receive daily either 0 micrograms PST (C) or 70 micrograms PST/kg initial BW for either 21 (PST-3) or 42 d (PST-6). Gilts were examined for estrus daily by a mature boar starting on d 22 and continuing for up to 50 d. Gilts that expressed estrus were mated and removed from treatment. PST-treated gilts had higher ADG (P less than .01) and lower feed/gain (P less than .02) than C gilts. Following initiation of boar exposure, C gilts (mean interval to estrus = 2.0 d) exhibited estrus earlier than PST-3 (24.8 d) and PST-6 (24.0 d) gilts (P less than .07); however, only two C gilts were observed in estrus compared with six PST-3 and six PST-6 gilts. In Exp. 2, 40 prepubertal gilts (72.6 +/- 1.0 kg; 141.1 +/- .7 d) were allotted randomly to receive daily either 0 mg PST (C) or 5 mg PST for 30 d. On d 31, half the gilts were comingled with unfamiliar penmates and examined for estrus daily by a mature boar for up to 45 d. Estrual gilts were removed from treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of the stage of the estrous cycle and novel cows upon mounting activity of dairy cattle.

The objectives of this study were to determine directly if mounting activity in dairy cattle varied as a function of stage of the estrous cycle and to determine if mounting by cows could be stimulated when novel estrous cows were introduced. Detector cows were normally cycling. Estrous cows were ovariectomized and injected with estradiol cyprionate and progesterone to induce standing estrous behavior. Familiar estrous cows (prior exposure to detector cows) and novel estrous cows (no prior exposure to detector cows) encountered each detector cow (n = 19) in a one-on-one manner for a 10-min period. Mounting activity by detector cows was determined by observation on d 5, 10, 15, day of estrus and d 5 of the subsequent cycle (52). The first d 5 was considered an acclimation day and was deleted from the data because all estrous cows (n = 4) used were novel. These novel estrous cows then became familiar estrous cows on the subsequent days (10, 15, estrus, 52). On these days, familiar (n = 4) and novel (n = 2) estrous cows encountered individually each detector cow in a prearranged sequence. Stage of the estrous cycle influenced (P less than .001) the frequency of mounting by detector cows. Mounting activity of detector cows was inversely related (r = -.64, P less than .001) to concentrations of plasma progesterone. The introduction of novel estrous cows tended to stimulate (P = .07) mounting when all days were considered. In addition, the introduction of novel estrous cows stimulated (P less than .001) mounting on d 15 and 52. A second experiment was conducted to determine if the introduction of novel estrous cows stimulated mounting in the detector cows on the day of estrus if a longer encounter time (30 min) was used. A total of eight detector cows and eight estrous cows (four familiar and four novel) were used. When the detector cow was in standing estrus, she encountered one-on-one each of two familiar estrous cows and each of two novel estrous cows in a prearranged sequence for 30-min. The introduction of novel estrous cows stimulated (P = .001) mounting by the detector cows on the day of estrus (6.50 +/- .48 vs. 4.37 +/- .48 mounts for N and F cows, respectively). We conclude that mounting activity is reduced during midcycle and that the introduction of novel cows stimulated mounting activity on d 15, day of estrus and on d 5 of the estrous cycle.

Development of one-cell porcine embryos to the blastocyst stage in simple media.

Porcine embryos were flushed from mated donors and examined for cleavage stage. One- and two-cell embryos were randomly allotted to one of the five following in vitro treatments: M199 with Earle's salts, a modified Tyrode's medium (TL), TL supplemented with 10 mM N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid (HEPES) (TLH), TLH supplemented with 5.5 mM glucose (TLHG), or TLH supplemented with 5 mM glutamine (TLHGL). The bicarbonate concentration of TLH, TLHG, and TLHGL was 2 mM, compared with the 25 mM concentration in M199 and TL. Embryos in M199 and TL were incubated in 95% air:5% CO2 at 39 degrees C. Those in the remaining three treatments were incubated in air at 39 degrees C. Embryos incubated in TL and M199 did not develop past the four- to eight-cell stage, whereas the proportions of embryos developing to the compact morula or blastocyst stage by d 7 of culture in the other treatments were as follows: TLHG, 49.1%; TLHGL, 59.4%; TLH, 63.5% (P less than .005). These results indicate that porcine embryos can be cultured from the one-cell stage to blastocyst in a simple HEPES-buffered medium in air. The ability of porcine embryos to develop without supplemental CO2 may be an important finding for use in situations in which embryos must be transported for long periods before embryo transfer.

Effects of exogenous porcine growth hormone (pGH) on growth, carcass traits, reproductive characteristics, and meat sensory attributes of young boars.

Two studies were conducted to examine the possible reduction in odors in fat and loin samples from boars treated with porcine growth hormone (pGH). In Exp. 1, boars were treated with either 0 (control: C), 3.5, or 7 mg of pGH daily from 72 to 119 kg BW. Treatment with pGH improved feed efficiency (P less than .05) but did not affect ADG, concentrations of testosterone in plasma, or aroma of cooked meat (all P greater than .05). Boars treated with pGH had less average backfat depth and marbling (both P less than .05) than C boars. Tenderness of the meat was reduced (P less than .05) by pGH treatment compared with control boars and contemporary barrows. Fat odors of pGH-treated boars were intermediate to those of barrows and control boars. In Exp. 2, boars were treated with vehicle (C) beginning at 62 kg BW or with 5 mg of pGH from either 65 kg (L) or 77 kg (H) BW to 118 kg BW. Average daily gain was higher in Group H than in Group C; Group L was intermediate. Average fat depth was lower (P = .0005) in Groups H and L than in Group C. Treatment had no effect on loin eye area, muscle marbling, texture, firmness, or pH, but color scores of Groups L and H tended to be different from each other (P = .06), and Group H muscle had more free water than that of Groups C and L (P less than .05). Weights of reproductive organs were unaffected by treatment (both experiments: P greater than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of constant versus adjusted dose of exogenous porcine growth hormone (pGH) on growth and reproductive characteristics of gilts.

Growth, carcass traits, and selected reproductive characteristics were evaluated in prepubertal gilts treated with either a constant mass of pGH or a mass of pGH adjusted periodically for changes in BW. Gilts (64 kg, n = 24) were given 24 daily injections of either vehicle (C; control) or one of two doses of pGH: 70 micrograms/kg of BW, with dose adjusted every 5th d for changes in BW (A; adjusted), or 70 micrograms/kg of initial BW (U; unadjusted). Gilts were slaughtered on d 25. Gilts treated with pGH had higher ADG (P less than .002) and improved feed efficiency (kg of feed/kg of gain; P = .0003) compared with controls. Weights of adrenal glands, liver, heart, and kidney were higher (all P less than .01) for Groups A and U than for Group C gilts. Average backfat thickness was less (P less than .004) for A and U gilts than for C gilts and less for Group A than for Group U (P less than .02). Furthermore, growth and carcass traits were similar (P greater than .05) for Groups A and U, except for measurements of first rib backfat, last rib backfat, and average backfat depth (P less than .05). Culture of granulosa cells (GC) was employed to assess ovarian function. Addition of FSH to the culture media enhanced secretion of progesterone (P4) by cultured GC from all in vivo treatments compared with unsupplemented cultures of GC (P less than .05). Addition of LH to the culture media enhanced secretion of P4 by cultured GC from pGH-treated gilts only (P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Fetuses of lean and obese swine in late gestation: body composition, plasma hormones and muscle development.

The development of obesity in porcine fetuses was investigated using a lean and obese strain of pigs at 80, 90, 100 and 110 d of gestation. In absolute terms, fetuses of obese gilts (FO) generally had lower carcass weight and contained less total protein, dry matter and ash than fetuses of lean gilts (FL). In relative terms (percentage of wet carcass weight) FO, compared with FL, generally had decreased percentages of water and increased percentages of protein and lipid. Comparisons based on absolute terms revealed body composition of the strains to be different at 90 d, indicating that factors responsible for obese-type growth were active before that time. Both body composition and hormone concentration differences were most pronounced at later gestation ages. Depressed growth hormone, elevated cortisol, and a tendency toward elevated insulin concentrations in fetal plasma were apparent in late gestation for FO compared with FL. These hormonal patterns are consistent with onset of obesity in FO in late gestation. Greater weights of semitendinosus and longissimus muscles were observed in FL vs FO at 90, 100 and 110 d of gestation (P less than .05). These greater muscle weights were generally accompanied by greater contents of RNA, DNA and protein in FL muscles at these same ages. However, at 80 d, FL had greater absolute DNA content in semitendinosus muscle whereas muscle weight was similar between the strains. This suggests that greater muscle weights for FL than FO were caused by more nuclei in muscle of FL. In general, indices of hypertrophy (protein/DNA) and protein synthetic capacity (RNA/DNA) of muscle were usually similar for both strains at all gestation ages. It is concluded that decreased muscle growth in late gestation of FO compared with FL is more related to fewer total nuclei and perhaps fewer myofibers than to an impaired cellular capacity for protein synthesis.

Reproductive and growth responses of gilts to exogenous porcine pituitary growth hormone.

Forty gilts (mean wt = 72 kg) were administered daily either vehicle (C = control) or 70 micrograms porcine growth hormone (pGH)/kg BW. After 30 d of treatment, eight gilts per group (Exp. 1) were slaughtered and blood, uteri and ovaries were collected. Follicular fluid (FFl) was collected and granulosa cells (GC) were cultured. The remaining gilts (Exp. 2) were treated for up to 35 additional days and examined twice daily for estrus. Estrusal gilts were removed from the experiment. Noncyclic gilts (n = 9 of 12 pGH; n = 4 of 12 C) were slaughtered on d 66 and their ovaries were examined. Ovarian weights were not different for pGH and C gilts in either Exp. 1 (P greater than .1) or Exp. 2 (P = .09). Uterine weights were greater for pGH-treated than for C gilts (P less than .007) in Exp. 1, but not in Exp. 2. Concentrations of estradiol (E2) in plasma and FF1 and of progesterone (P) in plasma and FF1 were not different for pGH and C gilts. Concentrations of insulin-like growth factor-I (IGF-I) in FF1 and in serum were greater for pGH than for C gilts (P less than .01). Concentration of P in serum-free medium of cultured GC was lower for GH than for C (P less than .05) in the presence or absence of gonadotropins in Exp. 1. The FSH-stimulated secretion of P was also lower for GC of pGH-treated gilts in Exp. 2, indicating a failure of GC to differentiate in culture. Only one pGH gilts in Exp. 2 manifested estrus, compared with seven C gilts (P less than .025). In Exp. 1, ADG was higher (P less than .03) and feed/gain lower (P less than .07) for pGH gilts. Longissimus muscle area (LMA) was not different (P = .19) between groups. Backfat thickness (BF) was lower (P less than .005) in pGH than in C in both Exp. 1 and 2. We conclude that exogenous pGH increased growth rate, improved feed efficiency and altered carcass traits in gilts. However, these effects were associated with impaired ovarian development of prepubertal gilts and a low incidence of estrus.

Relationship between progesterone and egg production in pheasants.

A radioimmunoassay was developed to measure progesterone concentration in sera of immature and mature female pheasants. The antiserum to progesterone was produced against progesterone-3-carboxymethyloxime: bovine serum albumin in female rabbits. Crossreactivity of the antiserum with 17 different steroids was tested and was less than 2% for all steroids except 5 alpha-pregnane-3,20-dione (18%) and pregnenolone (9%). Sensitivity of the standard curve was 2.7 pg. The within and between assay coefficients of variation were 7% and 14%, respectively. Blood samples were collected weekly starting when the birds were 17 weeks of age and continued until they were 1 year of age. Progesterone concentration was measured in all serum samples. Egg production was recorded daily for the individual hens. The relationship between progesterone concentration and egg production was studied. Average progesterone concentration prior to sexual maturity was significantly lower than at subsequent ages. There was a significant positive correlation between average progesterone concentration and average percent egg production within individual birds. Furthermore, statistically a significant amount of the variation in percent egg production was explained by differences in progesterone concentration. These results indicate that progesterone is important for egg production in pheasants, as it is in chicken and turkey hens.

Effects of nutrient intake and sexual age of the dam at mating on fetal development in swine.

Fifty-four Duroc gilts (mean wt = 88 kg, mean age = 164 d) were fed a 15% protein diet either ad libitum (F) or at a rate of approximately 50% of ad libitum daily (1.8 kg: L) prior to mating at either second (Exp. 1) or first (Exp. 2) observed estrus. Gilts were checked for estrus twice daily with a mature, active boar, mated at the appropriate estrus, and fed 1.8 kg of the prebreeding diet per gilt daily until slaughter between 42 and 49 days of gestation, mated gilts were slaughtered and measurements taken on fetuses and reproductive organs. In Exp. 1, fetal weight per day of gestational age (FetWDA), placental weight (PLW), crown-to-rump length (CRL) and uterine space per fetus (SP) were greater for fetuses from L gilts than F gilts (all P less than .05) with no difference in number of fetuses (P greater than .05). In Exp. 2, FetWDA was greater for fetuses from F gilts than L gilts (P less than .05), however there was no difference due to level of feeding for PLW, CRL and SP (all P greater than .10). Fetal weight (FW) was highly correlated with CRL indicated that a cubic relationship existed (both r = .97). In both studies, male fetuses grew more rapidly than female fetuses (P less than .05). These studies indicate that pre-breeding nutritional status and sexual age of the dam at conception have differential effects on fetal growth rate, but relationships among FW and CRL are not readily altered by pre-breeding level of feeding or sexual age of the dam at conception.(ABSTRACT TRUNCATED AT 250 WORDS)

Placental and fetal development in straightbred and reciprocal crosses of Yorkshire and Ossabaw swine.

Placental and fetal development were compared in 7 Yorkshire (Y) and 12 feral, Ossabaw (F) gilts mated to Y and F boars to produce straightbred and reciprocal cross litters (YY, YF, FY and FF, sire listed first). Gilts were slaughtered at d 75 +/- 2 of gestation. Ovulatory rate and litter size were higher in Y than in F gilts; however, rates of embyonal survival were similar in all groups. Groups differed in fetal body weight, metabolic body weight, crown-to-rump length, placental weight, metabolic placental weight and placental surface area, respectively. The YY group had highest values and the FF group smallest values for all variables except placental surface area. Pearson product-moment correlation coefficients of placental development with fetal length and weight across breeding groups were significant (e.g., placental surface area: fetal length, r = .67; placental surface area: fetal metabolic body weight, r = .76). It is concluded that the relationship between placental and fetal development observed in domestic swine is present in feral swine and crosses between domestic and feral swine at this gestational stage. These developmental measures are significantly influenced by fetal genotype and uterine environment but also by the breed of sire.

The effect of exogenous testosterone on homospermic and heterospermic fertility in the cock.

Cocks were administered testosterone (T) for 14 days via 0, 1, 2, or 4 Silastic capsules implanted subcutaneously. Each capsule released 1.04 mg of T per day. Concentrations of T in plasma and the proportion of eggs fertilized from homospermic insemination of hens were determined. Concentrations of T in plasma were variable and unaffected by treatment. The proportion of eggs that were fertilized by cocks decreased during treatment with 1 capsule, increased over the experiment in the group with 2 capsules, and increased after treatment ended in the group with 4 capsules. In heterospermic tests, cocks with distinguishable offspring were paired and semen was mixed within pairs. One cock in each pair received either 1 or 4 Silastic capsules containing T for 14 days; the other cock in the pair received none. The proportion of chicks sired by cocks treated with 1 capsule remained unchanged throughout the experiment, whereas the proportion sired by cocks treated with 4 capsules decreased markedly during the recovery period. The response to T was apparently dependent upon dosage and the sensitivity of the cock to T. The concentration of T in the plasma of the cock had little relationship to fertility. These results indicate that heterospermic insemination can be used as a sensitive method to detect the subtle effects of hormonal treatment.

Detection of the effects of ingested caffeine on fertility of cocks by homospermic and heterospermic insemination.

Cocks were fed diets containing 0, 0.025, 0.05, 0.075 or 0.1% caffeine during a 14-day treatment period. The number of spermatozoa produced by cocks fed 0.075 or 0.1% caffeine declined sharply at 12 days after onset of treatment. Hens were inseminated with a constant number of spermatozoa from individual cocks. The fertility of cocks fed 0.05, 0.075 or 0.1% caffeine declined during the 17-day post-treatment period and then returned to pretreatment levels. Cocks whose offspring were distinguishable were paired and relative fertility was assessed in a heterospermic test. One cock in each pair was fed 0.05% caffeine during the treatment period. Hens were inseminated with semen mixed within pairs. The proportion of chicks sired by cocks fed caffeine decreased during treatment and remined at that level until 17 days after treatment, when it increased to pretreatment levels. The percentage of total eggs hatched declined concomitantly with the reduction in the proportions of chicks sired by treated cocks. These results indicate that the effect of low levels of a toxin could be detected by reduced numbers of eggs hatched after heterospermic insemination with semen of normal appearance.

Effects of porcine follicular fluid and oviduct-conditioned media on maturation and fertilization of porcine oocytes in vitro.

Advances in porcine in vitro fertilization have been impaired by low normal fertilization rates resulting from a high rate of polyspermy. The present study was undertaken to determine the effects of porcine follicular fluid (pFF) and oviductal explant-conditioned medium on maturation and fertilization of porcine oocytes in vitro. Oocytes and pFF were collected from small, medium, and large follicles and pooled within size category. Maturation and fertilization media were supplemented (10%) with either fetal calf serum (FCS) or pFF (either fresh or snap-frozen). Snap-frozen pFF from small (3.1-5.0 mm) and medium (5.1-7 mm) follicles, respectively, increased maturation rates of oocytes from small and medium follicles by nearly 36% (p < 0.05) compared with those treated with FCS or fresh pFF. Supplementing media with either fresh or snap-frozen pFF from medium follicles reduced (p < 0.05) polyspermy of oocytes from small follicles by 30% compared with supplemental FCS. Snap-frozen pFF increased (p < 0.05) normal fertilization compared to that in fresh pFF (29% vs. 18%). Supplementing oocytes from medium follicles with snap-frozen pFF yielded the lowest (18%, p < 0.05) polyspermy rate. Oocytes from both small and medium follicles supplemented with pFF and/or conditioned medium (CM) from oviducts of periovulatory gilts exhibited a 95% improvement in normal fertilization rate and a 34% decrease in polyspermy rate compared to those treated with FCS (p < 0.05). CM from oviducts of luteal gilts did not improve rates of polyspermy and normal fertilization (p > 0.05). We conclude that snap-frozen follicular fluid from medium follicles and CM from cultured oviducts of periovulatory gilts improve in vitro maturation, reduce polyspermy, and increase normal fertilization rates in vitro.

Restriction of uterine space reduces litter size in feral Ossabaw swine.

The influence of uterine crowding on litter size and the fetal capacity of the feral pig uterus were examined in a control (C) group and three groups of surgically altered feral (Ossabaw) gilts. The altered groups were unilaterally ovariectomized (UOX), unilaterally tubally ligated (UTL), or unilaterally hysterectomized-ovariectomized (UHOX). Litter sizes of C, UOX and UHOX at 30 days of gestation were similar and larger than the UTL group. At 45 days, litter size was reduced (P less than 0.06) in UHOX gilts. These results indicate that uterine capacity of feral swine is limiting after Day 30, and that the maximum litter size for the feral pig is 8 to 10.

Response of porcine oocytes to electrical and chemical activation during maturation in vitro.

These studies were conducted to examine activation of in vitro-matured porcine oocytes in response to an electrical stimulus or to an ionophore. Cumulus-enclosed porcine oocytes were incubated in maturation medium supplemented with either FSH and LH (MM:Exp.1) or pregnant mare serum gonadotropin (PMSG; MM-P: experiments 2-4) at 39 degrees C in 5% CO2:95% air with high humidity. In experiment 1, groups of oocytes were stripped of cumulus and then shampulsed (control) or electrically pulsed with a Zimmerman Cell Fusion unit at 24, 31, 41, 48, and 65 h of incubation. Control oocytes were exposed to the activation medium for 20 sec, whereas oocytes to be pulsed were subjected to a single activation pulse (120 V, 30 microseconds). Oocytes were cultured for an additional 24 h and then fixed and examined. For oocytes pulsed at 24, 31, 41, 48, and 65 h, the proportions which activated were 0, 0, 87, 88, and 83%, respectively. In experiment 2, oocytes were electrically or sham-pulsed with a BTX 200 Embryomanipulation System at 24, 30, and 40 h of incubation and respective proportions of oocytes activating were 27%, 39%, and 72%. In experiment 3, oocytes were subjected to 0, 1, or 2 activation pulses after 41 h of incubation in MM-P. Double-pulsing halved the proportion of activated oocytes (P less than .0001). In experiment 4, oocytes were subjected to 0, 25, 50, or 100 microM ionophore at 48 h of incubation. Proportions of oocytes activated by ionophore were greater than for control (P less than .05), but activation was not increased by increasing dose of ionophore.(ABSTRACT TRUNCATED AT 250 WORDS)