Avaliação da classificação de bovinos da raça Nelore submetidos à prova de eficiência alimentar em diferentes idades

Abstract

Obtaining the characteristic of residual feed intake (RFI) is carried out based on food efficiency tests, whose regulation is accompanied by genetic improvement programs to standardize collections. The protocol consists, among the guidelines, of animals with a minimum age of two months after weaning and a maximum of up to 24 months, but there is a lack of information about the influence of age in this evaluation. Therefore, the objective of this work is to verify the effect of age on the ranking of Nellore cattle in terms of feed efficiency. 34 Nellore animals were evaluated, all males, born in November / December 2018, with an initial average age of 465 days (15.51 months), in which they were submitted to a food efficiency test using an electronic consumption measurement system. Intergado®. The RFI of each animal was calculated in three scenarios, general test, step 1 test and step 2 test and were classified. To check if there was a change in the classification of the classified animals, Spearman's correlation was used. The general test shows the animals' initial age 465 ± 13.75 days, initial weight 322 ± 43 kg, final weight 451 ± 52.92 kg, average daily gain (ADG) 1.3 ± 0.190 kg / day. The stage 1 test has a final weight of 378 ± 48.76 kg, ADG 1.270 ± 0.226 kg / day, age and initial weight similar to the general test. The stage 2 test has 510 ± 13.75 days, initial weight 380 ± 48.85 kg, final weight 438 ± 52.22 kg and ADG 1.32 ± 0.222 kg / day. The results of Spearman's correction found in this study were significant for all estimates (P <0.05). Spearman's correlations were moderately high for RFI_Etapa1 compared to RFI_Etapa2 of 0.56, ADG_Geral in ADG_etapa2 was 0.90, being very high. ADG_Geral for ADG_etapa1 obtained a high correlation of 0.76, ADG_Etapa1 and ADG_Etapa2 0.49, a moderate correlation. It was noticed the great influence of the variation of the classification for RFI, from one stage to another, being able to conclude that there is a difference in the classification of the animals for the RFI when evaluated in different ages.