Effects of different protocols of adaptation to high-concentrate diets for feedlot Nellore cattle

Abstract

The present study aims to assess the effects of duration of different adaptation protocols to high-concentrated diet on performance, animal temperament, feeding behavior, carcass characteristics, variations in dry matter intake, blood metabolic profile, blood concentration of endotoxin lipopolysaccharides binding protein (PBPs), incidences of ruminitis, liver abscess, morphology and histology of the rumen papillae on Nellore steers (cattle) finished in feedlot. Male Nellore steers (n = 120, with 385 kg on average) from the system rearing graze , will be kept in 24 pens with concrete floor, with a capacity of five animals per pen, and the space reserved per animal will be 5.4 m² and 0.4 m feeders. The treatments used are: T1 - adaptation steps (Step up) for 6 days (S6), T2 - adaptation steps (Step up) for 9 days (S9), T3 - restriction protocol for 6 days (R6), and T4 -restriction protocol for 9 days (R9), thus constituting a randomized completely experiment in 2 × 2 factorial arrangement (2 adaptation protocols and 2 adaptation periods) with measurements taken every 28 days. Each treatment will consist of six pens, which will be considered the experimental units for this study.The adaptation steps (step up) consist of feeding diets with increasing levels of concentrate according to the adaptation times (days) until they reach the level of concentrate desired to the finishing diet. For restriction protocol, finishing diet limited by quantity was used and the daily offer was gradually increased until ad libitum intake was reached. The experimental and adaptation diets will be offered twice a day (8h: 00min and 15h: 00min). After the adaptation period all animals will receive a single finishing diet with 85% concentrated to achieve live weight of 490 kg and backfat thickness at least 4.0 mm, when they will be slaughtered in commercial slaughter. (AU)