Based on results from eight experiments, no overall difference was found between roll tube and three-and five-tube most-probable-number (MPN) methods for estimating total numbers of ruminal bacteria. However, standard errors for the replicate means within an experiment were higher with the MPN procedures. Visual growth and pH were the criteria used for scoring the MPN tubes. Total numbers were significantly higher in MPN medium containing 40% ruminal fluid, as compared with a complete medium without ruminal fluid. By using a broth medium containing ball-milled cellulose and soluble carbohydrates as energy sources, it was possible to estimate both total and cellulolytic ruminal bacterial numbers in the same MPN series. Disappearance of cellulose and decrease in pH were used to determine growth. Values did not differ from those obtained in separate MPN assays. By using this method, diurnal changes in total and cellulolytic bacterial numbers were estimated in sheep fed forage or a concentrate-type diet.

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Three experiments were conducted to evaluate the effect of exposure of the uterus to semen at least 3 wk before breeding on subsequent reproductive performance. In Exp. 1, uterine exposure to semen was performed three times. At least 3 wk elapsed between each treatment. Control gilts received saline infusion. All gilts were bred by artificial insemination using semen from the same boars used for semen treatment. At farrowing, significantly more (10.35 vs 8.39) pigs/litter were produced by semen-treated gilts than controls. However, due to a disease outbreak (porcine parvovirus) during the last two-thirds of the farrowing period, live pigs born and litter size at 2 wk were not statistically different between the two groups. Gilts that farrowed were rebred and no difference in their reproductive performance for second litters was noted. For Exp. 2 and 3, a single semen treatment was given using freeze-thaw killed semen at estrus before breeding. Within both Exp. 2 and 3, semen-treated gilts had a larger average litter size, but no significant differences were detected. When data for nondiseased animals in Exp. 1 and animals in Exp. 2 and 3 were pooled, it was found that total pigs born (P less than .01), live pigs born (P less than .01) and live litter birth weight (P less than .1) were all greater in semen-treated gilts than in controls. Thus, these results indicate that reproductive efficiency in gilts can be improved by intrauterine treatment with boar semen before insemination to elicit conception.

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