Abstract Feeding the boars correctly includes more than providing adequate nutrients to achieve optimum quantity and quality of semen production, but is also important for libido, viability, and longevity of boars. The objective of this study is to evaluate the effects of working boar body condition, as assessed by caliper (v3), on survivability. Data was obtained from 2 North America PIC boar studs with 600 boar working inventories from Oct 2024 through Sept 2025. Visual body condition score (BCS; using a 1 to 5 scale with 1 and 2 being considered thin) was assessed monthly as well as caliper units measured (scale of 6 to 22). The boars were fed 2.3 kg per day before reaching 230 kg or 550 d of age and 2.5 kg per day after 230 kg or older (diet energy 3070 kcal ME/kg). Those considered thin (BCS 1 or 2) were fed 0.25 kg/d additionally until returning to ideal (3 or greater BCS) condition. Boar age had little evidence for correlation with caliper unit score (R2=0.03). Data were also analyzed using Kaplan-Meier survival plots and hazard ratios using Cox regression models. Boar served as the experimental unit and caliper score category ( 16 (L16) or =16 (G16) units) as the strata. Removals were classified as involuntary (died, sperm quality/libido, feet and legs, or health) or voluntary (genetic). The voluntary removals were considered as censored data points. Survival curves were generated individually for PIC 337, 800 and maternal lines (PIC 2, 3, and 19). Boars within each line category and with 16 or greater caliper units had improved (P 0.01) survival compared to those with less than 16 caliper units. Median survival for 337 boars was 815 d of age for L16 and 1231 d for G16, for 800 boars was 795 d for L16 and 1022 d for G16, and for maternal boars was 554 d for L16 and 1003 for G16. The hazard ratio for 337 L16 boars compared to G16 boars was 1.9 (95% CI 1.1-3.4), for 800 boars 1.9 (95% CI 1.3-2.9), and for maternal boars 3.3 (95% CI 2.3-4.9). There was no evidence for differences (P 0.10) in sperm production between caliper category when accounting for age. However, due to the increased median survival for the G16 strata lifetime sperm production is expected to be greater. In summary, these observations suggest under-conditioned boars (below16 caliper units) are at a greater removal risk.
Guo et al. (Wed,) studied this question.