Faculdade de Zootecnia e Engenharia de Alimentos, Universidade de So Paulo, Pirassununga, SP, Brazil

1
Phenotypic correlations between residual feed
intake, growth, carcass traits and reactivity in
Nellore bulls (Bos indicus).
Tiago Roberto Stella , Paulo Roberto Leme ,
Saulo da Luz e Silva , José Bento Sterman Ferras
, Rodrigo da Costa Gomes , José Carlos Machado
Nogueira Filho , Pedro Zillig da Silva Neto
Faculdade de Zootecnia e Engenharia de
Alimentos, Universidade de São Paulo,
Pirassununga, SP, BrazilCorresponding author
tiagostella_at_usp.br
RESULTS
INTRODUCTION Residual feed intake (RFI) is a
feed efficiency trait phenotypically independent
of growth rate and mature weight. Breeding beef
cattle for improved RFI may reduce feeding costs
and increase profitability of beef business.
However, associations between RFI with production
traits and animal behaviour were not studied in
Nellore cattle
Table 1 Means and standard error of means of
age,weaning weight,birth weight, yearling weight,
post weaning weight gain, reactivity score, feed
intake, RFI, feed convertion, Longissimus muscle
area and backfat thickness.
OBJECTIVE In this sense, it was aimed to
evaluate phenotypic correlations between residual
feed intake (RFI), growth, carcass traits end
animal behavior in Nellore bulls.

• MATHERIAL AND METHODS
• A total of 96 Nellore young bulls, born in 2005
  and 2006.
• The weaning weight (WW), birth weight (BW),
  yearling weight (YW), post weaning weight gain
  (WG) and reactivity score (animal agitation when
  restrained in the squeeze chute) were take.
• The animals were evaluated for RFI in 2007 and
  2008, respectively.
• They were fed individually for 68 days with a
  diet containing 68 of TDN and 14.3 CP..
• The weight and ultrasonic measurements of
  Longissimus muscle area (REA) and backfat
  thickness (BF) on the 12th and 13th ribs were
  obtained every 21 days.
• Pearson correlation analysis was performed
• Probabilities lower than 5 were considered
  statistically significant.

Table 2 -Phenotypic correlations between
residual feed intake, rate of gain of carcass
components and production rates of Nelore bulls
WW weaning weigth, BW birth weight, YW
yearling weight, WG post wearning weight gain,
FCR feed convertion, RFI residual feed intake,
REA Longissimus muscle area, BF backfat
thickness, RCT reativity Plt(0,001),
Plt(0,05), Plt (0,1).
CONCLUSION Residual feed intake was not
associated with growth, body weight and carcass
traits in Nellore