Fertilization and blastocyst development in oocytes obtained from prepubertal and adult pigs

Polyspermic fertilization and embryo quality are important issues for the in vitro production of pig embryos. We hypothesized that oocyte donor (prepubertal gilt vs. sow) affects polyspermy and blastocyst development in vitro and that the sexual maturity of the oocyte donor affects the response to sperm concentration in the fertilization medium. In Exp. 1, oocytes of sows and gilts were mounted and stained 12 h after insemination to provide fertilization data. In Exp. 2, putative embryos were developed in vitro to 144 h post-insemination before mounting. In both experiments, cumulus-oocyte complexes (COC) were collected from ovaries of prepubertal gilts and adult sows. Sperm were added after maturation of COC for 40 to 44 h. Sperm from two boars at 0.5 to 5.0 x 10(6) sperm/mL was used for insemination. More (P < 0.01) monospermic fertilizations were observed in oocytes derived from gilts than for oocytes from sows. There were fewer (P < 0.02) penetrated sperm per fertilized oocyte in oocytes from gilts compared with sows. There were effects of semen donor (boar) on the percentage of monospermic (P < 0.01) and polyspermic (P < 0.002) fertilizations, and on the number of penetrated sperm/fertilized oocyte (P < 0.02). In Exp. 2, cleavage and blastocyst formation was evaluated at 2 and 6 d postinsemination, respectively. More (P < 0.001) blastocysts developed from sow-derived oocytes than from gilt-derived oocytes. More (P < 0.05) total cells per blastocyst were observed in embryos from sow-derived oocytes than from gilt-derived oocytes. Semen donor affected the percentage of oocytes cleaving (P < 0.02), and a boar x sperm concentration interaction affected (P < 0.05) the incidence of blastocyt formation. Results indicate that sexual maturity of the donor is not responsible for the high incidence of polyspermy in porcine in vitro fertilization. However, blastocyst development is improved by the use of oocytes from sows rather than from prepubertal gilts.     

Relationship of growth hormone, prolactin and thyrotropin secretion to individual and progeny performance of Hereford bulls

Six Hereford bulls from a line selected with an index of body weight and muscling score were compared with six bulls from a control line to determine if increased growth in the selected line was associated with changes in plasma levels of growth hormone (GH), prolactin (PRL) and (or) thyrotropin (TSH). The predictive value of sire hormone data for growth rate of progeny was also evaluated. Bulls of the index line were heavier at birth (P less than .02) and had higher postweaning daily gains (P less than .01) than bulls of the control line. Blood samples were collected from bulls (ages 2 and 3 yr) at 15-min intervals for 8 h. Overall plasma GH concentrations were higher (P less than .03) in the index bulls than those in the control line. All characteristics of PRL secretion examined tended to be higher in the index bulls, but only mean overall and baseline differences approached significance (P less than .10). There were no significant differences in measures of TSH secretion between lines. Sire differences in hormone characteristics accounted for significant amounts of variation in birth weight and postweaning gain of progeny, but not in gain to weaning. Also, when considered jointly, hormone characteristics generally added significantly to predictions that used sire growth rate alone. The results suggest that serum hormone characteristics in parents may provide additional predictors of growth rates of progeny.     

Evaluation of reconstitution of immunodeficient mice by partially purified thymic extracts.

Partially purified thymus products were used to evaluate the maturation of T lymphocytes in immunodeficient mice. Three different bovine thymic extracts, designated thymic extracts A, B, and C, were successful in increasing the longevity of conventionally raised nude mice. Daily injection of bovine thymic extracts A, B, and C and mouse thymus extracts failed to mature a population of T lymphocytes and restore the capacity to reject heart allografts. Preincubation of normal syngeneic bone marrow with thymic extract B in vitro before injection into nude mice also failed to reconstitute the host's ability to reject heart grafts. The number of antibody plaque-forming cells of sheep red blood cells in lethally irradiated, bone marrow-reconstituted mice could be increased by preincubating the bone marrow cells with bovine thymic extract fraction B before injection followed by daily injections. A similar but less marked increase in plaque-forming cells was obtained by the daily injection of bovine thymic extract fraction C. Complete functional maturation of T lymphocytes in immunodeficient animals appears to require more than thymic extract stimulation of bone marrow cells or pre-T lymphocytes.     

Pharmacokinetics of oral terbinafine in adult horses

The primary study objective was to compare the pharmacokinetics of p.o. terbinafine alone to p.o. terbinafine administered with p.o. cimetidine in healthy adult horses. The second objective was to assess the pharmacokinetics of terbinafine when administered per rectum in two different suspensions at 30 mg/kg to adult horses. Six healthy adult horses were included in this crossover study. Plasma terbinafine concentrations were quantified with liquid chromatography and mass spectrometry. The half‐life (geometric mean) was 8.38 and 10.76 h, for p.o. alone and p.o. with cimetidine, respectively. The mean maximum plasma concentrations were 0.291 μg/mL at 1.54 h and 0.418 μg/mL at 1.28 h for p.o. alone and p.o. with cimetidine, respectively. Terbinafine with cimetidine had an average C_MAX 44% higher and the relative F was 153% compared p.o. terbinafine alone, but was not statistically different (P > 0.05). Terbinafine was infrequently detected when administered per rectum in two different suspensions (water or olive oil). Minor adverse effects included oral irritation, fever, and colic. All resolved spontaneously. More pharmacokinetic studies are indicated assessing drug–drug interactions and using multiple dosing intervals to improve our knowledge of effective oral dosing, the potential for drug accumulation, and systemic adverse effect of terbinafine in horses.     

Pharmacokinetics of oral omeprazole in llamas

Gastrogard, an oral formulation of omeprazole, was given to six llamas at a dose of 4 mg/kg once a day for 6 days. Plasma samples were collected at 0, 15, 30, 45, and 60 min and 2, 3, 4, 6, 8, 12, and 24 h on days 1 and 6. Plasma omeprazole concentrations were measured by high-pressure liquid chromatography with ultraviolet detection. Pharmacokinetic parameters calculated included the area under the curve (AUC(0-infinity)), peak plasma concentration (Cmax), time of peak plasma concentration (Tmax), and terminal half-life (t(1/2)). On day 6, plasma omeprazole concentrations reached a Cmax of 0.12 microg/mL at a Tmax of 45 min. The t(1/2) of omeprazole was 2.3 h and the AUC(0-infinity) was 0.38 h x microg/mL. Plasma concentrations remained above the minimum concentration for inhibition of gastric acid secretion projected from other studies on day 6 in all the llamas for approximately 6 h. However, the AUC(0-infinity) was below the concentrations associated with clinical efficacy. It was not possible to measure oral systemic bioavailability because there was no i.v. data collected from these animals. However, using data published on the i.v. pharmacokinetics of omeprazole in llamas, oral absorption was estimated to be only 2.95%. Due to low absorption the oral dose was increased to 8 and 12 mg/kg and studies were repeated. There were no significant differences in Cmax, Tmax, or AUC(0-infinity) for either of the increased doses. These results indicate that after 6 days of treatment with doses up to 12 mg/kg, oral omeprazole produced plasma drug concentrations which are not likely to be associated with clinical efficacy in camelids.     

Spermatic and oxidative profile of domestic cat (Felis catus) epididymal sperm subjected to different cooling times (24, 48 and 72 hours)

Cooling stored epididymal samples for several days allows facilities to transport and process genetic material post‐mortem. Improvements to this practice allow the preservation of sperm from domestic cats, which are the ideal study model for wild felids. However, the modifications in spermatic features and the oxidative profile are not fully understood in cats. This information is necessary for the development of biotechniques, such as new extenders for cryopreservation. Therefore, the purpose of this study was to evaluate the spermatic and oxidative profile in samples from the epididymal cauda of domestic cats cooled at 5°C for 24, 48 and 72 hr. Spermatozoa were collected from the epididymis cauda. Evaluations consisted of computer‐assisted sperm analysis (CASA), plasma membrane integrity (eosin/nigrosin), acrosome integrity (fast green/rose bengal), sperm morphology, sperm DNA integrity (toluidine blue), mitochondrial activity (3′3 diaminobenzidine), activity of the antioxidant enzymes glutathione peroxidase (GPx) and superoxide dismutase (SOD), measurement of lipid peroxidation (TBARS) and protein oxidation. A decrease in sperm motility parameters was observed after 72 hr of cooling (i.e. total and progressive) with a higher percentage of minor (37.7 ± 6.3%) and total defects (53.4 ± 6.3%). Additionally, a decrease in high mitochondrial activity (Class I: 16.6 ± 2.2%) occurred after 72 hr. The decrease in motility rates after a long cooling time probably was caused by the increase in sperm abnormalities. A long cooling time causes cold shock and mitochondrial exhaustion, but there was no observed change with the oxidative stress condition. Therefore, cat epididymal sperm stored at 5°C appear to maintain a high quality for up to 48 hr of cooling time.     

Specification of pen rail spacing and trough heights to prevent escape and enable good access to feed by sheep during sea shipments from New Zealand

A trial was carried out to determine the optimal height of feeding troughs above floor level and the spacing between pen railings which would enable sheep to access feed troughs but prevent them from getting out of pens during sea voyages. The trial involved a group of 16 large (79 kg) wether sheep and 24 small (30 kg) wether lambs which were held in pens and trained to eat lucerne pellets. Feed troughs similar to those used on ships were constructed 260 mm deep and 220 mm wide. A system of adjustable railings were used to alter the trough height and to determine the optimal spacing to allow the large sheep to get their heads through, but to prevent small sheep from escaping. In order that sheep of various sizes can access feed from the bottom of feed troughs, the height of the top edge of the trough should not exceed 360 mm above floor level for 30 kg sheep or 460 mm for mature sheep. This range is due to differences between the groups in their shoulder height, and variation between individuals within each group. Shoulder heights of the small sheep used in this trial ranged from 505 to 590 mm, and for the 16 mature animals the range was 610-715 mm. It is important that the feed troughs are low enough for all animals to access the feed on offer. Mature sheep were able to pass their heads between rails spaced at 200 mm without difficulty, but some difficulty was experienced when the space was reduced to 180 mm. The maximum rail spacing which prevented the escape of 30 kg lambs could not be determined with certainty because they could pass through a space of only 180 mm when laid on their side, but the smallest space through which they passed voluntarily was 220 mm. Hence the optimal spacing between railings which would allow all sheep good access to feed and would prevent almost all small sheep from escaping is about 190-210 mm.