Abstract

Background and Aim: An increased proportion of female piglets is desirable in commercial swine breeding to improve productivity, facilitate genetic selection, and reduce the need for male castration. However, currently available sex-selection techniques, such as flow cytometry, are costly and impractical for routine field use. This study evaluated the potential of rabbit serum albumin (RSA) as a low-cost biochemical modulator to influence the proportion of female offspring, comparing its effects with those of other albumin sources and determining optimal supplementation conditions for boar semen used for artificial insemination (AI). Materials and Methods: Eight Landrace boars were initially screened in vitro to assess sperm quality and the proportion of X- and Y-bearing sperm following incubation with albumin. Four boars (A, B, E, and G) showing a higher X-sperm proportion were subsequently selected for in vivo trials involving 130 sows. Semen was diluted in a conventional extender supplemented with albumin (RSA, porcine serum albumin, or bovine serum albumin) or left unsupplemented (control). The effects of albumin source, concentration (0.1–0.2 mg/mL), incubation temperature (25°C vs. 37°C), duration (5–15 min), and boar variation were examined. Offspring sex ratio and litter size were analyzed using the Kruskal–Wallis test, followed by Dwass–Steel–Critchlow–Fligner pairwise comparisons (p < 0.05). Results: All albumin treatments significantly increased (p < 0.05) the proportion of female piglets compared with controls. RSA yielded the greatest effect, particularly at 0.1 mg/mL incubated at 37°C for 15 min, producing up to 61.8% female offspring compared with 24.8% in controls. Boars with an initial male-biased sex ratio showed the largest improvement after RSA treatment. Although litter size decreased slightly with albumin supplementation, the difference was not statistically significant (p ≥ 0.05). Conclusion: Supplementation of semen extenders with RSA effectively increased the proportion of female piglets without compromising fertility. This method offers a practical, scalable, and economical alternative to conventional sex-sorting technologies for swine breeding. Further optimization and larger-scale validation are warranted to ensure consistent litter performance and broader adoption in commercial production systems.