Autores
Thaís Matos Ceacero, Joslaine Noely dos Santos Gonçalves Cyrillo, Roberta Carrilho Canesin, Marcela Morelli, Lúcia Galvão de Albuquerque, Maria Eugênia Zerlotti Mercadante
Genetic and phenotypic correlations of feed efficiency with growth traits in Nellore cattle
Resumo
Feed efficiency
is difficult to evaluate because individual feeding are required. An
alternative is selecting animals based on traits easier to obtain and
genetically favorably correlated with feed efficiency traits. This study aimed
to estimate genetic and phenotypic correlations between feed efficiency traits (residual
feed intake – RFI, feed efficiency – FE and residual BW gain – RG) with yearling
weight (YW), hip height (HH) and girth
circumference (GC) in Nellore cattle. Feed efficiency data set consisted of 887
records of DMI, ADG and BW0.75 obtained during performance tests (83
± 15 d) to calculate RFI (0.005 ± 0.58 kg DM/d), FE (0.14 ± 0.03) and RG (0.00 ±
0.11 kg/d). FE was calculated as ADG and DMI ratio, RFI was estimated as the
error of multiple regression of DMI on ADG and BW0.75, and RG was
estimated as the error of multiple regression of ADG on DMI and BW0.75. The YW data set
consisted of 7,948 records of males (314.45 ± 45.85 kg) and females
(282.68 ± 48.19 kg)
adjusted to 378 and 550 d of age, respectively. The HH consisted of 6,418 records
of males (131.80 ± 5.40 cm)
and females (132.51 ± 5.38
cm), and 3,745 records of GC of males (162.56 ± 8.48 cm) and females
(167.72 ± 8.08 cm).
Pedigree
file contained 9,830 animals. Growth traits were
analyzed as unit standard deviation of each sex/age. (Co)variance
components were estimated through two-trait animal models by restricted maximum
likelihood method using MTDFREML software. For RFI, FE and RG traits, models
included fixed effect of test group (year-sex-facility), linear effect of
animal age in the middle of performance test, linear and quadratic effects of
dam age, and random effects of direct additive genetic and error. For growth
traits models included the fixed effects of contemporary group (year-herd-sex)
and month of birth, linear effect of animal age, linear and quadratic effects
of dam age, and random effects of direct additive genetic and error. For YW model
also included the permanent environmental effects of dam. RFI showed null genetic
and phenotypic correlations with growth traits, however, low and favorable
genetic correlation between RFI and HH was observed. Genetic correlation of FE (low
and positive) and RG (high and positive) with growth traits were favorable to select
animals with efficiency of growth and feed. Moreover, phenotypic correlation between
EF and GR and HH were negative (Table 1). Growth traits can be used as
indicators of feed efficiency traits in beef cattle.
Correlações genética e fenotípica entre características de eficiência alimentar e características de crescimento em bovinos Nelore
Abstract
Íntegra (PDF)