Effects of lactation length and an exogenous progesterone and estradiol-17beta regimen during embryo attachment on endogenous steroid concentrations and embryo survival in sows

The hypotheses that short lactation lengths increase embryo mortality by altering endogenous post-weaning steroid concentrations, and that an exogenous steroid regimen during embryo attachment might increase embryo survival were tested using 36 s parity sows assigned randomly to a 2 x 2 factorial. Sows were subjected to either a short lactation (SL, 13.0 days, n = 25) or a long lactation (LL, 31.5 days, n = 11), artificially inseminated at first estrus and treated daily with 2 ml i.m. of either 25 mg progesterone (P4) and 1.25 pg estradiol-17beta (E2) (steroid treatment, ST, n = 17) or the vehicle alone (control treatment, CT, n = 17) on Days 14-20 post-insemination. Blood samples were collected by jugular venipuncture from weaning to 24 days post-insemination on alternate days. Sows subjected to the SL compared to the LL tended to have a longer weaning-to-estrus interval (WEI) (5.3 versus 4.6 days; P < 0. 10), but did not have a significantly reduced conception rate (CR) (71 versus 90%; P > 0.10). The SL and LL sows had a similar ovulation rate (19.9 versus 21.3 corpora lutea, CL; P > 0.05), but SL sows had fewer viable embryos than LL sows (11.5 versus 15.3; P < 0.05) when reproductive tracts were recovered 28-32 days post-insemination. In addition, even after correction for the difference in number of embryos between groups, viable embryos from the SL versus the LL group weighed less (1.63 versus 1.79 g; P < 0.05), had a decreased amnion volume (1.02 versus 1.22 ml; P < 0.05) and apparently produced less estrogens since estrone sulfate concentration was decreased at 24 days post-insemination in SL versus LL sows (4.3 versus 6.3 ng/ml; P < 0.05). Embryo survival (percentage of CL represented by a viable embryo) however, was not different between SL and LL sows (60 versus 74%; P > 0.05) and no differences in post-weaning P4 or E2 concentrations were apparent. Sows that received the ST only tended to have increased P4 concentrations at 16 days post-insemination compared to CT sows and neither the number of viable embryos, nor embryo survival, was increased in ST versus CT sows (14.7 versus 12.2; P > 0.05 and 66 versus 68%; P > 0.05, respectively). These data suggest that short lactations do not increase embryo mortality by inducing aberrant endogenous post-weaning P4 or E2 concentrations. It is unclear whether or not small, repeated doses of exogenous P4 and E2 during attachment can increase embryo survival.

State of the art in artificial insemination of pigs in the United States

Currently, the United States ranks second in pork production worldwide. In 1999 the breeding herd consisted of approximately 6.2 million breeding females with an annual production of 100 million market animals having an average market live weight of 118.6 kg. The objective of this paper is to briefly describe the current US swine artificial insemination (AI) industry and to profile semen production and insemination practices that are currently in use.

Hormonal and behavioral correlates of emotional states in sexually trained boars

Physiological and behavioral traits of sexually mature boars were compared between episodes of copulation and sexual frustration in order to determine reliable indicators of the differences in emotional states. Ten boars, approximately 6 mo of age, were trained to mount a stationary artificial sow (ArtSow) and to ejaculate when digital pressure was applied to the extended penis. This method of semen collection is the typical procedure of the industry. All 10 boars used in this study were fully trained to this procedure before the onset of the study. Each boar was subjected to trials in which one of the following two treatments was applied. In the control (CTRL) treatment, boars were treated the same as during their training (i.e., allowed to complete ejaculation). In the frustration (FRUS) treatment, boars were allowed to mount the ArtSow, but because no manual pressure was applied to the extended penis, ejaculation never occurred. Blood was collected via indwelling catheters before onset of the trial, during exposure to the ArtSow, and after returning to their home pen. Concentrations of testosterone, cortisol, and beta-endorphin were quantified. Behavior of the boars was recorded during exposure to the ArtSow and for 30 min after return to their home pen. Relative to preexposure levels, serum cortisol increased (P<.05) during CTRL exposure and after exposure to both treatments (CTRL; P<.04 and FRUS; P<.06). Serum testosterone did not change during and after either treatment. Serum concentrations of beta-endorphin did not change during or after CTRL trials, but serum beta-endorphin was greater (P<.05) during FRUS than during CTRL trials. Behavioral analysis revealed that boars spent less time lying down and more time moving about their home pen (P<.05) after a FRUS than after a CTRL trial. In summary, serum cortisol did not allow us to distinguish between the excitement of copulation and the negative affect associated with sexual frustration, whereas increases in serum beta-endorphin and motor activity seemed to be indicators of the negative emotional state of sexual frustration in trained boars.

Failure of vitamin A to increase litter size in sows receiving injections at various stages of gestation

To determine the effectiveness of a single injection of vitamin A to increase litter size, 1,375 sows were assigned randomly to 11 treatment groups (125 sows per treatment). Treatments included injection of 1 x 10(6) IU of vitamin A dissolved in corn oil at weaning or on d 0, 2, 6, 10, 13, 19, 30, 70, or 110 after breeding. Sows in the control group were injected with corn oil on corresponding days. A total of 396 sows were removed from the study following treatment or treatment assignment. Therefore, farrowing data were collected for 979 sows. Injection of vitamin A did not influence (P > . 10) total litter size, live litter size, litter weight, pig weight, number of runts, or number of mummies. Mean live litter size was 10.1 +/- .1 for all sows that farrowed in the experiment. Parity group affected total litter size, live litter size, live litter weight, and number stillborn (P < .01) but not pig weight, number of runts, number of mummies, or gestation length (P > . 10). In this study, a single injection of vitamin A at any time from weaning to farrowing did not increase litter size in sows.

Surgical correction of severe vaginal introital stenosis in female baboons (Papio sp.) infected with simian agent 8

Simian agent 8 (SA8) is a neurotropic, endemic alphaherpesvirus in Papio sp. Lesions associated with simian agent 8 infections usually involve the genitalia of sexually mature baboons. In females, secondary bacterial infections may lead to scarring of the vulva and perineum, with resulting vaginal obstruction. Affected baboons are poor breeders and often develop urinary tract infections due to retention of urine in the vagina. Reconstructive vaginal surgery was performed on seven baboons with vaginal obstruction. Four weeks before surgery, 50 mg of Depo-Provera was administered intramuscularly to each animal to arrest the estrous cycle, reduce swelling, and allow adequate surgical exposure of the vagina. Ventral and circular incisions were made around the constricted vagina. The peripheral skin was excised to break down the underlying connective tissue, allowing access to the vaginal mucosa. Healthy vaginal tissue was then opposed to the incised skin edges with 3-0 Vicryl in an interrupted pattern. Once healed, the vaginas remained patent, allowing normal mating and urination. Nine months after surgery, five baboons had healthy infants, and pregnancy was confirmed in the other two animals. The described procedure may allow female baboons previously infertile and at risk of urinary tract infections to be returned to a healthy reproductive state.

Use of farrowing rate as a measure of fertility of boars

The first 100 single-boar services of 140 boars were analyzed to determine whether the farrowing rate resulting from initial services predicted the farrowing rate of subsequent services. The data were analyzed for the influence of parity, number of matings per estrus, season of service, and interaction of these variables on farrowing rate. Sow parity influenced farrowing rate. Sows with parity greater than 8 and gilts had the lowest farrowing rates (P less than 0.01). Sows with parity 2 through 5 had the highest farrowing rates (P less than 0.01). One and 2 matings/estrus resulted in reduced farrowing rates (P less than 0.01), compared with farrowing rates of greater than 2 matings/estrus. Farrowing rate for services during the summer was lower than that for other seasons of the year (P less than 0.01). Evidence of interaction among these variables was not found. Therefore, the results of each service recorded was adjusted to the mean farrowing rate of sows with parity 2 through 5, sows mated greater than or equal to 3 times/service, and sows serviced in the spring. After these adjustments, the farrowing rates for the first 10, 20, 30, 40, and 50 services were analyzed to determine associations with farrowing rates for subsequent services through 100 farrowings. These data also were analyzed to determine whether the associations were strengthened by removal of the first 10 services from the data. The best farrowing rate association indicated that for each 1% increase in farrowing rate subsequent to the first 50 services, the farrowing rate for the second 50 services increased 0.33% (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

ReCAP: the Registry of Cytogenetic Abnormalities and Phenylketonuria

The Registry of Cytogenetic Abnormalities and Phenylketonuria (ReCAP) is a multicenter collaborative registry of information on patients with constitutional cytogenetic abnormalities or hyperphenylalaninemia (HPA). Data are entered by microcomputer at four contributing centers. Records are then electronically transmitted to the coordinating center, where the composite cytogenetic and hyperphenylalaninemia databases are maintained on a mainframe computer. A set of programs, known as the ReCAP ISCN Translator, is used to create additional database records describing in detail the chromosome abnormalities present in each patient. The ReCAP computer system permits rapid and flexible retrieval of cases on the basis of any combination of laboratory, clinical, psychometric, or genetic characteristics contained within the databases. Special procedures protect patient confidentiality and assure that ReCAP data are of consistently high quality. Qualified investigators may use ReCAP as a resource for a variety of scientific studies.

Effects of winter and summer energy levels on heifer growth and reproductive performance

Three heifer development trials were conducted with 337 crossbred heifers (125, 105 and 107 heifers in trials 1, 2 and 3, respectively) over a 3-year period. Heifers were fed low quality fescue hay ad libitum plus 0, 1.22 or 2.45 kg of ground ear corn (GEC) daily during the winter feeding phase of all three trials. Winter gains and final winter and summer condition scores increased (P less than .05) in each trial as winter level of GEC increased. In each trial, summer gains followed the reverse order of winter gains (P less than .05). Conception rate, mean number of days pregnant (as determined by rectal palpation) and adjusted weaning weight of progeny increased linearly with winter level of GEC when pooled over trials. Differences between animals fed 0 and 2.45 kg of GEC were significant. Conception rate and adjusted weaning weight of progeny of the heifers retained in the breeding herd increased (P less than .05) as level of GEC increased when data were pooled over trials. Calving date and percentage live progeny were not significantly affected by winter treatment. Summer daily gains and condition scores were increased by additional summer energy (2.45 kg GEC/day) in trial 3. Conception rate and mean number of days pregnant (conception date) favored heifers given the summer supplementary feeding (2.45 kg GEC) treatment. Among heifers retained in the breeding herd, there were no significant differences between the 0- and 2.45-kg GEC summer treatment groups in conception rate, calving date, percentage live progeny or adjusted weaning weight of progeny.