AUTORES

Severino Lendechy, V.H., Montiel Palacios, F., Ahuja Aguirre, C., Peralta Torres, J.A., Segura Correa, J.C. 2020. Feed supplementation affect age and weight at puberty in Girolando (Bos taurus x Bos indicus) heifers in the tropics. Livestock Science. 240: 1-6. ISSN: 1871-1413.

ABSTRACT

The effect of feed supplementation (FS) on age and weight at puberty, follicular population and progesterone concentration was determined in 80 Girolando heifers. Heifers were distributed in four treatments: T1) 8-month-old heifers that received FS (n = 20); T2) 8-month-old heifers that received no FS (n = 20); T3) 10-month-old heifers that received FS (n = 20); and T4) 10-month-old heifers that received no FS (n = 20). Body weight was recorded at the beginning of the study and then every 21 days. Daily weight gain, total weight gain and weight at puberty were then determined. Heifers in T1 and T3 each received 2 kg of feed supplement daily until the onset of puberty. Ovarian structures were examined by transrectal ultrasonography to determine the population of middle size (4.1-8 mm) and large size (≥8.1 mm) follicles, follicular growth of dominant follicles, ovulation and to confirm the presence of a corpus luteum (CL). Blood progesterone (P4) concentrations were collected on days 7 and 14 post-ovulation, using solid phase enzyme-linked immunosorbent assay (ELISA). Puberty was reached at an earlier age and heavier body weight in feed supplemented heifers. Follicular population, growth of the dominant follicle and blood P4 concentrations were higher (P<0.05) in the heifers given FS. Feed supplement reduced the age at puberty of heifers by 4 to 5 months in 8 and 10 months age groups. In addition, feed supplementation should be offered to 10 month-old heifers, instead of at 8 months, because this will shorten by 2 months the duration of supplementary feed.

Keywords: Dominant follicle; Follicular population; Heifer; Nutrition; Ovulation.