Disease & heat resistance

Selection for birth weight uniformity in the Iberian pig improves robustness and animal welfare

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Abstract

The uniformity of production traits is desired in livestock species. This type of selection will make livestock production more efficient with higher survival rates and longevity. Animals that are more uniform are easier for farmers to manage, improving animal welfare and robustness. In the context of breeding practice, within-litter birth weight (BW) variability is highly important for animal survival and welfare, as well as for economic considerations in the pig industry. A selection experiment to decrease BW variability has been conducted since 2022, in a Sánchez Romero Carvajal Iberian pig population, fattening in montanera system. The experiment design includes two replicates (154 sows and 14 boars) per discrete generation. The mating is optimised to maximise the genetic response while maintaining the global coancestry in the offspring in each replicate. The objective of this study was to analyse the data of this population selected for BW uniformity, and its impact on latter weights, survival and meat quality traits. The data included three generations of selection with a total of 864 litters from primiparous sows, totalling 5778 BW piglets and 1608 records in the pedigree. Genetic evaluation was performed using a heteroscedastic model including piglet sex (2 levels), batch (9 levels), litter size at birth (10 levels) and age of the sow (345-570 days) as covariate, as fixed effects. The litter and the maternal genetic effects were included as random effects. Same effects were included in the model for the mean trait and its variability. The analysis was performed using ASReml 4.2 and GSEVM. Total number born (TNB), weight at 21 days (W21), survival at birth (SB) and meat quality traits (loin intramuscular fat content and backfat composition of 12 fatty acids) were also studied to evaluate the impact of selection. The genetic variance for the BW variability was 0.18 (0.07) (genetic variation coefficient of 0.41 (0.08)), and the genetic correlation between BW and its variability was -0.28 (0.14). Regarding later weights, the genetic correlation between BW and W21 environmental variabilities was favourable indicating that selection for BW uniformity would also imply homogeneity in later pre-weaning weight. Phenotypic trends were positive comparing generation 0 and 3 for TNB (increase of 1.51 piglets) and for SB (increase of 4.68%). Regarding quality traits, the correlations with predicted breeding values for BW environmental variance were favourable, but moderate to low with fat% (-0.11) and beneficial fatty acids as Oleic+Linoleic% (-0.13). A 10% reduction in the present BW variability could be achieved without negatively affecting other traits. Therefore, selection for within-litter BW uniformity is recommended as a criterion in the breeding genetic index for this population. This study was funded by a grant PID2023-149012OB-I00 (RoPig).

Keywords: 2026

How to Cite:

Formoso-Rafferty, N., Gutiérrez, J., Muñoz, M., García-Casco, J., Pérez-Cabal, A., Perdomo-González, D., Ojeda-Marín, C., Calvente, F., Sánchez-Esquiliche, F. & Cervantes, I., (2026) “Selection for birth weight uniformity in the Iberian pig improves robustness and animal welfare”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285694. doi: https://doi.org/10.31274/wcgalp.23777

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