Reproductive performance of pandemic influenza A virus infected sow herds before and after implementation of a vaccine against the influenza A (H1N1)pdm09 virus

Table 2 Categorisation of farms prior to vaccination and respective means of return to oestrus rate after vaccination

category (range of return to oestrus rate)	n	decrease of the return to oestrus rate on n farms (%)	mean decrease of the return to oestrus rate by X% (SD)
1 (< 10%)	43	25 (58.1%)	1.56 (1.43)^a
2 (≥ 10% - < 20%)	66	52 (78.8%)	4.49 (2.87)^b
3 (≥ 20%)	22	21 (95.5%)	10.97 (5.4)^c

n = number of farms X = average decrease in the return to oestrus rate in the respective category after immunisation ^abc groups with different superscripts had significantly different results(p < 0.05)

ISSN: 2055-5660