Fixed part of the model for breeding value estimation in pigs based on litter size

Abstract

Abstract:The goal of this paper was to investigate the effect of various fixed effects on the number of born alive piglets in litter (NBA), based on results of Swedish Landrace sow fertility on three farms in Setbia, in order to determine the best adapted model for assessing genetic parameters and breeding value. Analysis of phenotipic variability of the NBA of Swedish Landrace sows was carried out based on fertility results on three swine farms (A, B and C) in the Republic of Serbia. Data sets encompassed reproduction indicators for 2803 (A), 1826 (B) and 2235 (C) sows, i.e. their 11014, 6757 and 8452 litters, respectively. For this analysis was used fix model of least square method which includes fixed effects of farrowing number, season of conception shown as combination of year and month, litter genotype, duration of previous period from weaning to conception, effect of sow age at farrowing like quadratic regression nested within farrowing number and linear regression influence of duration of previous lactation. The average NBA was within the interval from 9.13 (A) to 9.76 piglets (B and C). The monitored trait statistically highly significantly (p<0.001) varied under the effect of all systematic factors encompassed by the applied model, regardless of the source of analyzed data, Only the linear regression effect of duration of previous lactation for farm B was assessed as having lower statistical significance (p<0.05).

Influence of cycle stimulation in weaned sows on fertility depend on season

“…Effects such as farrowing number, age at farrowing, breeding season, length of previous lactation, or duration of the period from weaning to breeding, are parameters regularly recorded when monitoring sow fertility under all production conditions. Contrary to previously mentioned effects, effects such as housing, nutrition, diseases, or effects of boar are very rarely recorded, even though they influence the variation of number of born alive piglets to a considerable extent (Kosovac et al, 2005;Bößenrodt and Fischer 2005;Radojković et al, 2007).…”