Total gastrointestinal tract digestibility of neutral detergent fiber and total digestible nutrients of feedlot Nellore cattle adapted with different protocols

• Grant number: 12/04673-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: April 01, 2012
• End date: March 31, 2013
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Danilo Domingues Millen
• Grantee: Daniel Hideki Mariano Watanabe
• Host Institution: Universidade Estadual Paulista (UNESP). Campus Experimental de Dracena. Dracena , SP, Brazil

Abstract

The objective of this study will be to evaluate the length of protocols of adaptation to high concentrate diets on total tract digestibility of neutral detergent fiber (NDF) and total digestible nutrients (TDN) of Nellore cattle finished in feedlot. One-hundred twenty Nellore yearling bulls (361 kg) will be randomly allocated in 24 pens with five animals per pen according to the treatments: step up program during 9 days (S9), step up program during 14 days (S14), restriction program during 9 days (R9), and restriction program during 14 days (R14), characterizing a completely randomized block design with a 2 x 2 factorial arrangement of treatments (2 protocols of adaptation lasting 9 and 14 days) with repeated measures over time, which will be taken on days 0, 5, 10, 15, and 20 of experimental period. Each treatment will contain 6 replications (pens). The step up program consisted of ad libitum feeding of three adaptation diets over periods of 9 or 14 days with concentrate level increasing from 55% to 85% of diet dry matter. The restriction program consisted of restricted intake of the final diet (85% concentrate) with programmed increases in feed offered until yearling bulls reached ad libitum access over periods of 9 or 14 days. Feces and diets samples will be collected every 5 days, up to day 20. During collections, feces samples will be collect from the floor before morning (8h) and afternoon (15h) meals, and a composite sample per pen in each day will be frozen into -20ºC for future analysis. Afterwards, it will be performed chemical analyses to determine NDF and TDN concentrations in the samples as well as chromium oxide. Thus, it will be calculated the total tract digestibility of NDF and TDN. (AU)