The synthetic progestogen, allyl trenbolone, was fed daily to 60 gilts at 15 mg/gilt for 18 days. Sixty-eight gilts that came into estrus the same week as treated gilts served as controls. Gilts were checked for estrus twice daily and were artificially inseminated with frozen semen or bred by natural service. All but two treated gilts returned to estrus between 4 and 7 days after withdrawal of allyl trenbolone (mean = 5.6; SD = .82). The farrowing rate among gilts inseminated with frozen semen was significantly lower than that among gilts bred by natural service (52.5 vs 89.6%). The farrowing rate among synchronized gilts was similar to that among untreated gilts (70.7 vs 73.5%). Average total and live litter sizes at birth and litter size at weaning were significantly smaller for untreated gilts inseminated with frozen semen than for synchronized gilts inseminated with frozen semen or those of untreated gilts bred by natural service. Average litter size for synchronized gilts bred by natural service was not significantly larger than that for synchronized gilts inseminated with frozen semen or that of untreated gilts bred by natural service.
In the context of dairy grazing systems, pasture mixtures including tall fescue, lucerne and plantain have been identified by animal modelling as having potential to both improve milk production and reduce urinary nitrogen excretion. A grazed paddock-scale trial was established in the Waikato in September 2015 to test this in two short-term grazing trials including these species. This paper presents the pasture production, botanical composition and nutritive value data generated from four pasture mixtures sown in spring 2015 and sampled until autumn 2017 (18 months). The pasture mixtures represented a comparison between perennial ryegrass and tall fescue, with and without the herb narrow-leaved plantain. The inclusion of plantain in grass-lucerne mixtures had a positive effect on firstyear herbage dry matter (DM) production, by ~2.6 t DM/ha/year in ryegrass-based pastures and ~1.6 t DM/ ha/year in tall fescue-based pastures. Where plantain was included, the proportion of grass was reduced by more than half from autumn 2016 through to summer 2016-2017, while the proportion of lucerne was reduced to a lesser degree. The proportion of plantain was 35-70% through most of the first year, declining to
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