Probiotics supplements on fattening guinea pigs: effects on carcass traits and non-carcass components

The growing demand for animal protein is driving the search for natural alternatives, such as probiotics, following the ban on growth-promoting antibiotics due to bacterial resistance. The objective of this study was to evaluate the effect of including probiotics made from agro-industrial waste fermented with Lactobacillus acidophilus and Kluyveromyces fragilis and their combination on carcass traits, non-carcass components and colour and pH evolution during muscle-to-meat conversion of 90-day-old male guinea pigs. A total of 40 male guinea pigs were randomly assigned to one of four groups: (a) Ct, control group; (b) LA, supplemented with Lactobacillus acidophilus; (c) Kf, supplemented with Kluyveromyces fragilis; (d) LAKf, supplemented with a combination of L. acidophilus and K. fragilis. The combination of L. acidophilus and K. fragilis significantly increased live weight at slaughter compared to the control group, demonstrating synergistic effects between bacterial and yeast probiotics. Carcass yields (HCY and CCY) were not significantly influenced by probiotic supplementation, remaining within the standard ranges for the breed. Tissue composition showed proportional scaling with body weight, and non-carcass components development remained proportional to body size across treatments, indicating that growth benefits were achieved without imposing metabolic stress or requiring compensatory organ hypertrophy. Probiotic supplementation influenced meat colour parameters, particularly reducing yellowness (b*) and improving colour stability during chilling in yeast-containing treatments. The pH evolution during the post-mortem period was not affected by probiotic supplementation, indicating normal glycolytic processes and favourable conditions for meat quality development. These findings support the use of fermented agro-industrial substrates as effective probiotic delivery systems in guinea pig production, offering a sustainable approach that addresses both waste valorisation and animal nutrition challenges.