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Lactation length and litter size in pigs
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Pages 115 - 119
The aim of this study was to evaluate the influence of lactation length on the subsequent litter size. Three commercial farms were analyzed. Litter records with lactation length longer than 50 days and weaning to conception interval longer than 70 days were excluded from analysis. In statistical model for number of piglets born alive, lactation length was fitted on two ways. Firstly, lactation length was fitted as linear regression over whole interval, and secondly as linear regression nested within three intervals (1-17, 18-31, 32-50 days). Estimated regression coefficients over whole interval ranged between 0.016 and 0.035. Estimated regression coefficients by intervals were different. Regression coefficients on the interval from 18 to 31 day were higher than regression coefficients obtained over whole interval (1-50 day). But, predicted breeding value of sows for litter size did not showed any difference (r>0.998) between these two approaches. Therefore, modeling of lactation length as linear regression over whole interval seems to be sufficient.
litter size lactation length; pigs