Banca de DEFESA: ANNA CAROLINA DE CARVALHO RIBEIRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANNA CAROLINA DE CARVALHO RIBEIRO
DATE: 24/02/2022
TIME: 09:00
LOCAL: INSTITUTO DE ZOOTECNIA
TITLE:

Visual assessment of body structure, precocity and muscularity in beef heifers finished in feedlot

KEY WORDS:

Carcass dressing, frame-size, maturity, performance, reproduction, weight gain.

PAGES: 45
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUMMARY:

RIBEIRO, Anna Carolina de Carvalho. Visual assessment of body structure, precocity and muscularity in beef heifers finished in feedlot. 2022. 39 p. Master Degree (Animal Science, Animal Production). Instituto de Zootecnia, Universidade Federal Rural do Rio de Janeiro, Seropédica, RJ, 2022. The evaluation of visual scores helps to choose cattle for high efficiency and adapted to the production system. The hypothesis of the present study was that there is an influence of visual classification on production parameters. The aim of this study was to evaluate the effect of visual morphological classification on productive parameters in the finishing of heifers on feedlot. Thirty Nellore heifers (Bos indicus) were used, with an initial average body weight of 338±4,5kg, average age of 18 months, finished in feedlot during the dry season. The diet composed of 70% roughage and 30% concentrate was formulated for weight gain of 1.0 kg/animal/day. The visual morphological evaluation was performed in the middle third of the experimental period, using a comparative method, on a scale from 1 (one) to 6 (six), and classifying heifers according to: 1) body structure (small, medium and large); 2) precocity (late, medium and early), and 3) muscularity (less muscular, medium and more muscular). All females were evaluated by rectal palpation and ultrasound examinations weekly. The uterus evaluation was performed by measuring the diameter of both right and left horns, after cross sectioning immediately after the uterine bifurcation. Two measurements of the largest diameters of each horn cut were made and the average was calculated. The right and left ovaries were also evaluated according to their diameter, from the average of the two largest ovarian diameters, the diameters of antral follicles and corpus luteum were also checked. The estimation of fecal excretion, digestibility and consumption was performed using external (Lipe®: 500 mg) and internal (indigestible NDF) markers. Body weight was assessed weekly, and weight gain was calculated by the difference between final and initial weight. Feed conversion was calculated by dividing intake by weight gain, and feed efficiency was calculated by dividing weight gain by intake. At the end of the experimental period, the heifers were slaughtered in a commercial establishment, and the weights of the hot carcasses were taken to calculate the carcass dressing in relation to the live weight prior to slaughter. The effects of treatments, time and interactions were tested. Morphological classification had no effect on reproduction system morphometry (p≥0.11), neither time interaction (p≥0.24). No classification effects were detected for body structure (p≥0.14), precocity (p≥0.20) and muscularity (p≥0.12) on dry matter intake, weight gain, feed conversion and carcass dressing. The experimental hypothesis was rejected. However, the influence of time of feedlot on body weight and feed efficiency was observed. In both variables, there were no significant variations after 63 days of confinement termination (p<0.01), indicating maximum productive efficiency in the finishing phase of Nellore heifers in feedlot up to 424 kg of body weight.

BANKING MEMBERS:
Externa à Instituição - JANAÍNA JANUÁRIO DA SILVA - UFMT
Presidente - 2316004 - RONDINELI PAVEZZI BARBERO
Externa ao Programa - 2078607 - SABRINA LUZIA GREGIO DE SOUSA