THE EFFECT OF TWO INTRAVAGINAL PROGESTERONE DOSES AND OVUM PICK-UP OUTCOMES IN BROWN SWISS COWS: A BAYESIAN HIERARCHICAL ANALYSIS

QUISPE-EULOGIO C.; SANTIAGO-INGA N.; ANCCO-GOMEZ E.; NINAHUANCA J.; UNCHUPAICO-PAYANO I.; GARCÍA-HOSPINAL M.; RIVERA-PALOMINO C. · Online Journal of Animal and Feed Research (2026) · DOI: 10.51227/ojafr.2026.25

Resumen

This study evaluated the effect of two intravaginal progesterone doses on follicular recruitment, oocyte recovery, and oocyte viability in Brown Swiss cows undergoing ovum pick-up. Eight dry cows were allocated to two treatments: T1 (0.6 g progesterone) and T2 (1.2 g progesterone), with four cows per treatment and five repeated sessions per animal. The responses analyzed were the numbers of 2–4 mm follicles, 4–8 mm follicles, total recovered oocytes, recovery probability, and oocyte viability. Count data were analyzed with negative binomial models, whereas recovery and viability were modeled as binomial responses, with cow included as a random effect. Overall, T1 showed higher adjusted posterior means for the number of 2–4 mm follicles per ovum pick-up (OPU) session (7.62 vs. 5.36 follicles), 4–8 mm follicles per OPU session (4.17 vs. 3.27 follicles), and total recovered oocytes per OPU session (4.75 vs. 3.56 oocytes) compared with T2. Oocyte viability, expressed as an adjusted posterior probability, was also higher in T1 than in T2 (0.750 vs. 0.566, equivalent to 75.0% vs. 56.6%). In contrast, the adjusted posterior probability of oocyte recovery was nearly identical between treatments (0.403 vs. 0.402, equivalent to 40.3% vs. 40.2%). Among the evaluated outcomes, oocyte viability showed the clearest treatment difference, with an odds ratio of 2.50 and a posterior probability of superiority of 0.989 in favor of T1. Under the conditions of this study, the 0.6 g progesterone protocol was associated with a more favorable follicular response and better oocyte viability, while oocyte recovery efficiency remained essentially unchanged. © The Author(s) 2026

Instituciones: Universidad Peruana Los Andes; Universidad Nacional del Centro del Perú