Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2000
Publication Date: January 1, 2000
Technical Abstract: Postweaning growth and puberty were determined for Romosinuano heifers from germplasm collected in Costa Rica (CR; n=17) and Venezuela (VE; n=34) that 98 d prior to weaning were either allowed to creep graze rhizoma peanut (RP; n=26) or no creep (n=25). Postweaning, heifers were maintained on mixed bahiagrass and RP pastures (and hay) and fed 4.5 kg/d concentrate. Growth measurements were collected at the start of the study and at 28-d intervals for 358 d. Beginning three wk before the start of the breeding season and at 7-d intervals thereafter, blood was collected and plasma progesterone determined by EIA to assess puberty. At the start of the study, heifers from CR were older (236 vs 208 d), heavier (218 vs 183 kg), and taller (113 vs 110 cm) than heifers from VE. At the end of the study, heifers from CR were heavier (432 vs 387) and taller (132 vs 129 cm) than heifers from VE. During the study, however, neither gain in BW nor gain in hip height was affected by source of germplasm. Preweaning treatment did not affect BW or hip height at the start or end of the postweaning study; but non creep calves gained more BW than creep calves during the post- weaning study (216 vs 202 kg). Age at puberty was similar between heifers from CR (428 d) and VE (419 d) and between creep (419 d) and non creep (427 d) heifers. Hip height and BW at puberty were influenced by the inter- action of germplasm source x preweaning treatment. This appeared due to taller hip heights and heavier BW observed at puberty for CR-non creep heifers than for any other source-treatment combinations. Data from this study suggest that CR and VE heifers have similar postweaning growth rates and ages at puberty and that preweaning creep may depress postweaning gain in heifers but did not affect age at puberty.