Nutrient digestibility of feedlot cannulated Nellore cattle previously submitted to nutritional restriction or intake of concentrate feedstuffs

Abstract

The objective of this study will be to evaluate the effects of either previous nutritional restriction or previous intake of concentrate feedstuffs on nutrient digestibility of Nellore cattle. The treatments will be disposed as follows: Maintenance (forage ad libitum + mineral supplement); Restriction (forage restricted at 1,4% of body weight + mineral supplement), and Concentrate (forage ad libitum + 0,5% of body weight of a mix of concentrate feedstuffs and mineral supplement). It will be used 6 Nellore yearling bulls ruminally cannulated, with approximately 300 kg of body weight. Cattle will be in a 3 x 3 Latin square experiment, and randomly distributed in 6 pens, which will be considered the experimental unit. This study will last 115 days, in which each period will last 33 days with 2 washout periods (8 days each) between the periods 1 and 2, and 2 and 3. Each experimental period will be divided into 14 days of pre-adaptation phase, where treatments will be applied, 6 days of adaptation diet 1 (72% concentrate), 6 days of adaptation diet 2 (79% concentrate) and 7 days of finishing diet (86% concentrate). From the 5th to 13th day and 24th to 32th day of each experimental period animals will receive titanium dioxide (10 g/ animal/ day; 5 g in the morning and 5 g in the afternoon) through ruminal cannula, and from 10th to 14th day and from 29th to 33th day will be performed feces collections, twice times per day, for the future determination of the digestibility of dry matter, starch, neutral and acid detergent fiber and crude protein. (AU)