PSVIII-4 Impact of Different Forage Allowances During the Middle and Late Thirds of Pregnancy of Nellore Dams Pregnant with Female Calves on dam Performance

Abstract

Abstract The study aimed to evaluate the impact of forage allowance (FA) on performance, during pregnancy until weaning, of dams pregnant with Nellore female calves subjected to two different FA during the middle and final thirds of pregnancy. The experiment lasted 390 days, divided into two phases: gestational phase (150 days - from June to November 2019) and nursering phase (240 days - from November/2019 to July/2020). Multiparous Nellore n = 42; initial BW of 425 ± 36 kg and body condition score (BCS) of 3.67 ± 0.23] dams pregnant with female calves were used in a randomized block design (blocked by BW), with the experimental unit being the paddock and six replicates per treatment. The treatments consisted of two different FAs during pregnancy phase: low forage allowance (LFA; 2.80 kg of DM/kg of BW) and high forage allowance (HFA; 7.60 kg DM/kg BW). The dams were kept in an area composed of Urochloa brizantha cv. Marandu and received a protein supplement (1 g/kg BW/day). In the nursing phase, all animals remained in the same pasture conditions and supplementation (ad libitum mineral salt) until calves were weaned. The data were analyzed using the SAS PROC MIXED. Dams subjected to LFA had reduced BW (-35 kg) and BCS (-0.23) at calving (P< 0.01). All variables measured in the carcass, except marbling score (P=0.33), showed differences (P< 0.01) between treatments at calving, with the least values observed in the animals subjected to LFA. At weaning, dams subjected to LFA had reduced BW (-16 kg; P< 0.01). Dams subjected to LFA, at the level and period evaluated, probably went through feed restriction during the middle and final thirds of gestation, implicating lower performance and deposition of tissues in the pre and post calving until weaning.