Crossbred boars achieve greater semen-collection training success than purebreds, independent of environmental enrichment

Information from the abstract

Efficient training of boars for semen collection is crucial for artificial insemination (AI) programs, yet the relative contributions of genetics, rearing enrichment, and endocrine indicators remain uncertain. We compared sexual performance of purebred and crossbred males reared with environmental enrichment (EE) or in barren housing (BE) during growth and tested whether serum testosterone and salivary cortisol were associated with training success. Initially, 128 males were randomly allocated to EE (three alternating objects) or BE; after growth, 32 genetically approved boars were randomly selected and evaluated in a 2×2 factorial (line: pure vs. cross; rearing: EE vs. BE; n=8 pigs) across three sessions on alternate days (6 days; 96 sessions). “Trained” was defined as mounting the dummy and allowing collection. In total, 19/32 (59.37%) were trained; 41.66% of sessions featured unassisted mounts during acclimation, only 7.29% succeeded after handler stimulation/assistance, and 48.95% failed to mount despite assistance. Crossbreds showed higher libido scores and training rates than purebreds (P<0.001). Mean libido scores did not differ between EE and BE (P = 0.276), but EE groups yielded fewer trained animals, suggesting reduced mounting dexterity after enriched rearing. Ejaculate volume did not correlate with ejaculation time (P>0.05). Testosterone was higher in fasted than post-feeding samples (P<0.001) and higher in EE than BE (P<0.05), yet training success did not explain its variation (P = 0.50). Cortisol showed a genetic-line effect (crossbreds>purebreds; P = 0.034), no enrichment effect, and no association with trained/not-trained outcome (P>0.05); pre- vs. post-session means did not differ (P = 0.784). Our results suggest that crossbred boars improve semen-collection training performance, the EE regime tested provided no benefit and was associated with lower operational success, and single-time endocrine measures have low predictive value; prioritizing handler practices, acclimation routines, and standardized, welfare-focused protocols is recommended.

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Related topics: Animal Behavior and Welfare Studies · Sperm and Testicular Function · Reproductive Physiology in Livestock