Eficiencia energética de la producción de destetes en vacas Brahman (Bos indicus) y cruzadas (Bos taurus x Bos indicus) en Yucatán, México

Cow genotype effect was evaluated in energy efficiency of weaning production (EEWP), on three cow groups: 15 Brahman (Bos indicus) and 44 crossed cows (B. taurus x B. indicus) (11 Charolais x Brahman and 33 Brown Swiss x Brahman), breeding Brahman sire calves, under grazing extensive conditions in Yucatan, Mexico. Productive data of cows and calves was obtained, energetic expenses were calculated for every physiologic state and energy efficiency of weaning production was estimate (gram [g] of weaning weight produced per mega calorie [Mcal] of metabolizable energy [ME] consumed by cow and calf). There were statistic differences (p<0.05) in weight gain (881 ± 190 and 726 ± 165 g/d for calves of cros- sed and Brahman cows) and weaning weight (200 ± 35 and 166 ± 27 kg for calves of crossed and Brahman cows) of calves, despite cow genotype effect. Crossbred cows (B. taurus x B. indicus) had 13.1% (p<0.05) more EEWP than Brahman cows (19.8 ± 2.8 vs. 17.5 ± 2.7 g/ Mcal of EM for crossbred and Brahman cows). In Yucatan, Mexico, it is possible increase weaning production in a cycle, by the use of crossbred cows (B. taurus x B. indicus) under grazing conditions.El efecto del genotipo de vaca fue evaluado sobre la eficiencia energética de la produc- ción de destetes (EEPD), en tres grupos de vacas: 15 Brahman (Bos indicus) y 44 cruzadas (B. taurus x B. indicus) (11 Charoláis x Brahman y 33 Suizo Pardo x Brahman), criando becerros de sementales Brahman (Bos indicus), en condiciones de pastoreo extensivas en Yucatán, México. Se obtuvieron datos productivos de las vacas y sus becerros, se calculó el gasto energético de cada estado fisiológico y se estimó la eficiencia energética de la pro- ducción de destetes (gramos [g] de destete producidos por megacaloría [Mcal] de energía metabolizable [EM] consumidos por la vaca y el becerro). Existieron diferencias significativas (p<0,05) en la ganancia de peso (881 ± 190 y 726 ± 165 g/d para becerros cruzados y Brahman respectivamente) y peso al destete (200 ± 35 y 166 ± 27 kg para becerros cruzados y Brahman respectivamente) de los becerros, por efecto del genotipo de la vaca. Las vacas cruzadas (B. taurus x B. indicus) tuvieron 13,1% (p