Strategic feeding of the prepubertal Nellore heifers improves body development and increases the number of recovered oocytes, viable oocytes and embryos produced in vitro.

Abstract

The objective of this work was to determine the effect of two different feeding plans on quantity and quality of oocytes and in vitro embryo production, as well as on the body development of prepubertal Nellore heifers. After weaning, thirty-three Nellore heifers were divided into two experimental groups and supplemented with two nutritional plans according to dry and rainy seasons. For nutritional plan 2 the animals received diets containing 26% and 19% more metabolizable energy (ME) related to NP1 in the dry and rainy seasons, respectively. After 3.5 months of supplementation (i.e., at 10 months old), animals from both groups underwent follicular aspiration (OPU) every 21 days and in vitro produced embryos (IEP). Withers height, chest depth and body weight of all animals were measured monthly. Subcutaneous fat deposition was measured at the end of the study by ultrasonography. The number of retrieved COCs per OPU and viable oocytes was respectively 49% and 42% greater in NP2 heifers (p=0.018 and p=0.049). Regarding the blastocysts rate, heifers administered NP2 produced 29.7% of blastocysts, a percentage higher than NP1 treatment animals that produced 24.40% of embryos (p<0.05). Consequently, the females from NP2 treatment presented a greater final weight, chest depth, carcass finish, in addition to a greater accumulation of subcutaneous fat. These results indicating a positive effect of diet slightly higher in energy in the assisted reproduction of Nellore prepubertal heifers and also on weight gain and fat deposition in the carcass, allowing these females to reach the suggested early mating conditions.