Author(s): Košorok S, Kastelic M
Keywords:primiparous sows, fertility traits, P.G. 600®, seasonal fertility
P.G. 600® is often used as an estrus promoter on sows with controversial results. This experiment was carried on a well managed farm with 2,500 sows during one calendar year. Half of primiparous sows, 502 of a total of 1005, were treated with P.G. 600® at weaning. Three week observation time formed one batch of data with an adequate number of observations for statistical evaluation. Every batch was evaluated separately. Moderate improvement of reproduction traits was found in the experimental group. Both, the percentage of sows in estrus after weaning (95.98 % versus 94.99 %) and the percentage of sows farrowing the second litter (90.34%versus 88.38 %) was higher in the experimental than in the control group. Experimental group had a slightly larger litter (14.22 versus 13.85), shorter period to first estrus (6.16 days versus 7.10 days) and shorter period to successful insemination (8.10 days versus 8.56 days). Improvement of fertility traits was observed particularly in late winter, spring and early summer, but it was not confirmed by statistical evaluation. Unexplained variance in the statistical model was high. The use of P.G. 600® in well managed heards in Slovenian moderate climatic conditions is unnecessary. That conclusion cannot be generalised for other managements and climatic conditions.
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