The effect of non genetic factors on litter weight at birth and weaning in Dalland pig breed of Zimbabwe

Non-genetic factors influencing litter weight at birth and weaning  were evaluated using the Dalland pig breed of Zimbabwe. The objective of the present study was to establish the non genetic factors which affect average litter weight at birth (ALBWT) and weaning  (ALWWT) in Dalland pig breed of Zimbabwe. Mixed classification models containing effects of sire, ages at first service, gestation length, teat number, litter size at birth, litter size at weaning and year of birth and weaning were used  for identification of non genetic factors. The  ALBWT and ALWWT data were analyzed using the General Linear Models (GLM) procedure of the Statistical Analysis System (SAS), 1996 to establish the significance of the non genetic factors.  The mean litter weight  at birth and  weaning  were 12.53±0.13 and 24.22±0.07, respectively. Sire line and age at first service  had  significant effects (p<0.05) on both ALBWT and ALWWT. Litter size at  birth and year of birth had significant effects (p<0.05) on average litter weight at birth, while  teat number  influenced average litter weight at weaning. Two way factor interactions for age at first service *teat number and    age at first service* sire line had a significant effect (p<0.05) on average litter weight at weaning. The lowest average litter weight  both at birth and weaning were observed when the litter size was largest, 15.63±0.17 and 24.64±0.25, respectively. The inconsistency of literature results on the influence of non genetic factors on average litter weight at birth  and weaning in pig production within specific  sow units and environment indicates the importance of estimation of environmental factors for different pig production entities is necessary. The  study  alludes to the complexity of the non genetic factors  influencing the  average litter at birth and weaning in pig production, hence the need to correct for such non genetic factors for accurate estimation of genetic parameters