Effect of supplementation with different trace minerals sources and fibrolytic enzyme on the productive and reproductive performance of Nellore cows on pasture.

The present study aims to evaluate the productive and reproductive parameters of Nellore cows and their offsprings 15 on pasture when supplemented with Cu, Mn, Zn and Se from organic (ORG) and inorganic (ING) sources, alone and 16 with fibrolytic enzyme (ORG + ENZ and ING + ENZ), ninety-six multiparous Nellore cows were blocked by their body 17 weight and body condition score and randomly allocated to sixteen pastures (6 cows/pasture) in a randomized block 18 design with 4 blocks. The treatment structure was a 2 × 2 factorial arrangement. Milk production was estimated at 30 19 ± 0.5 days postpartum and reported as kg/24 h. Liver biopsies were performed on 12 cow-offspring pairs per treatment 20 on days - 30, 120, and 240 to determine liver tissue mineral concentration. There was no interaction between mineral 21 source, enzyme, and period for body weight (BW; P ≥ 0.72), average daily gain (ADG; P ≥ 0.51) or carcass 22 characteristics (P ≥ 0.12) of cows and calves. Cows supplemented with organic minerals produced calves with greater 23 rump fat thickness than cows supplemented with inorganic minerals, 3.90 and 3.63 ± 0.17, respectively. Calves from 24 the ING + ENZ treatment presented the highest Se concentration at 120 days after birth. The use of organic sources did 25 not affect the productive and reproductive performance of Nellore cows and their calves on pasture. The use of 26 exogenous enzyme resulted in greater marbling of cows without effects on the carcass characteristics of the calf.