PSI-20 Effect of Different Forage Allowances During the Middle and Final Thirds of Pregnancy in Nellore Dams Pregnant with Female Calves on Offspring Performance and Milk Yield

Abstract

Abstract This study was conducted to evaluate the impact of maternal nutrition, during the middle and final thirds of pregnancy of Nellore dams pregnant with female calves, on the milk yield of the dams and on the performance of the offspring from calving to weaning. The experiment lasted 390 days, divided into two phases: gestational phase (150 days - from June to November 2019) and nursing phase (240 days - from November/2019 to July/2020). Forty-two multiparous Nellore dams pregnant with female calves were used [initial BW of 425 ± 36 kg and body condition score (BCS) of 3.67 ± 0.23] in a randomized block design (blocked by BW), with the experimental unit being the paddock and six replicates per treatment. The treatments consisted in two forage allowances (FA) during pregnancy: low forage allowance (LFA; 2.80 kg DM/kg 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 suckling phase, all animals remained under the same conditions of pasture and supplementation (ad libitum mineral salt) until weaning. Data were analyzed using SAS PROC MIXED. Corrected milk yield (4% fat) and total milk fat and solids content were affected by the FA (P< 0.04), with the least values observed in the milk of animals subjected to LFA. female calves from dams subjected to LFA during pregnancy were 11 kg lighter (P=0.02) and showed adecreased average weight gain (-0.08 kg/day) at 120 days from calving (P=0.03), and also showed less rib-eye area (-3.10 cm²) at weaning (P =0.03). Dams subjected to LFA during pregnancy possibly went through nutritional restriction, which caused changes in milk yield and milk composition during nursing phase, implicating lower performance of the offspring until weaning.