Feedlot performance of Nellore and ½ Angus/Nellore cattle adapted either for 9 or 14 days

Author(s)

Daniel Hideki Mariano Watanabe

• Document type: Master's Dissertation
• Press: Dracena. 2016-04-28.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Tecnológicas. Dracena
• Defense date: 2016-03-03
• Advisor: Danilo Domingues Millen

Abstract

The objective of this study was to evaluate the length of adaptation period to high concentrate diets on performance, feeding behavior, carcass traits, rumen health and starch, NDF and DM digestibility of Nellore and ½ Angus/Nellore cattle finished in feedlot. Seventy-two yearling bulls (313.5 kg ± 24.5 on the average), 36 Nellore and 36 ½ Angus/Nellore, backgrounded on pasture were randomly allocated and kept in 24 pens (3 animals/pen) with concrete floor (24 m² and 2,0 m bunk per animal) according to the treatments: Nellore adapted for 9 days, Nellore adapted for 14 days, ½ Angus/Nellore adapted for 9 days, and ½ Angus/Nellore adapted for 14 days, characterizing a randomized block design with a 2 x 2 factorial arrangement of treatments (2 genotypes and 2 lengths of adaptation period) with repeated measures over time according to the dependent variable measured. Each treatment was composed by 6 pens which was considered the experimental unit to this study. After 9 or 14 days of adaptation, yearling bulls received the finishing diet containing 86% concentrate. At the beginning of experimental period and every 28 days, yearling bulls were weighted. Dry matter intake was measure every day, and average daily gain and feed efficiency were calculate. Likewise, the deposition of muscle and fat were evaluate by ultrasound at the beginning and at the end of the study where the yearling bulls were slaughter in a commercial abattoir after 89 days of feed reaching average live body weight of 446.2 kg. Samples of rumen epithelium, diet, refusals and feces were collected for analysis of rumen health, and nutrients digestibility, respectively. Animals ½ Angus/Nellore presented better (P<0.05) performance, feed efficiency and carcass traits than the Nellore. Interaction (P<0.05) to rumenitis was observed, where Nellore adapted in 14 days presented the higher score. Yearling bulls adapted in 14 days presented (P<0.05) selection against particles higher than 19.0 mm and selection in favor of the particles lower than 1,18 mm. Animals adapted in 9 days showed higher DMI variation (P<0.05) than the adapted in 14 days during the adaptation period. Thus, it is possible to concludes that the most security adaptation length to both genotypes is the 14 days and the better genotype to feedlot performance is the ½ Angus/Nellore. (AU)

• FAPESP's process: 13/21666-7 - Performance, feeding behavior, carcass traits, rumen health, and starch digestibilty of Nellore and 12 Angus/Nellore cattle adapted in feedlot for 9 or 14 days
• Grantee: Daniel Hideki Mariano Watanabe
• Support Opportunities: Scholarships in Brazil - Master