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, Brazil
§Corresponding author: [email protected]
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
Traits
Animals
Age, days
Weaning weight, kg
Birth weight, kg
Yearling weight, kg
Post weaning weight gain, kg
Reactivivity score
RFI
Feed intake, kg
Feed convertion
Mean
96
645
209
240.5
362.62
153.78
3.1
-0.004
8.65
5.65
SEM
Longissimus muscle area, cm2
Backfat thickness, mm
15.8
3.34
0.4
0.13
5.33
3.3
2.8
4
3.4
0.05
0.05
0.08
0.08
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
WW
BW
YW
WG
FCR
RFI
0.75*** 0.56*** -0.33 *** -0.20** -0.05
REA
BF
RCT
-0.007 0.20*
0.12
-0.22** -0.12
-0.07
0.05
0.23*
0.59*** -0.37*** -0.05
-0.06
0.04
0.29**
0.17*
-0.06
-0.14
0.17*
BW
0.75***
0.56*** 0.03
YW
0.56*** 0.56***
WG
-0.33 *** 0.03
FCR
-0.20** -0.22** 0.37***- 0.17*
RFI
-0.05
-0.12
-0.05
-0.02
0.4***
REA
-0.007
-0.07
-0.06
-0.06
0.14
BF
0.20*
0.05
0.04
-0.14
-0.23** 0.13
RCT
0.12
0.23*
0.29** 0.17*
0.59***
-0.02
0.4*** 0.14
0.15
0.15
-0.23** -0.19**
0.13
-0.001
-0.14
-0.002
-0.14
-0.03
-0.19** -0.001 -0.002 -0.03
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
*** = P<(0,001), ** = P<(0,05), * = P< (0,1).
CONCLUSION
Residual feed intake was not associated with growth, body
weight and carcass traits in Nellore