Influência de dias de teste na mensuração do ganho de peso médio diário de bovinos Senepol em avaliação para eficiência alimentar

Abstract

The objective was to evaluate the influence of the test period in the measurement of the average daily gain (ADG), for the purposes of genetic evaluation in feed efficiency of Senepol cattle. The experiment was carried out at the Federal University of Uberlândia (UFU), at the Fazenda Experimental Capim Branco, located in the city of Uberlândia, MG. Twenty-five male Senepol animals were used, born in 2018, with an average age at the beginning of the test of 13.6 months, from 4 different farms. The food efficiency variables studied were: average daily gain (ADG; kg / day) and average metabolic live weight (AMLW; kg / day). Five evaluation scenarios were considered in the prediction of ADG and AMLW: 70-day test period with daily weighings (REF); 42-day trial period with daily weighings (1); 35-day trial period with daily weighings (2); 70-day trial period with weighing at 14-day intervals (3); 56-day trial period with weighing at 14-day intervals (4). A Spearman correlation was used to check the classification of animals in different scenarios in relation to the REF scenario. It was found that scenario 3 obtained the highest Spearman correlation (0.84) in relation to the REF scenario, that is, 70.56% of the animals classified for ADG not alternated in the ranking. The second best proposal for the test period was scenario 4, in which a Spearman correlation coefficient of 0.81 was obtained, where 65.61% of the animals did not transfer in the ranking. It was observed that the biggest change in the ranking of the animals was found in scenario 2, in which only 32.49% of the animals maintained the same ranking in relation to the REF scenario, for the ADG. It was verified, through Spearman's correlation coefficients for AMLW, that all animals maintained or even ranked in the other scenarios in relation to REF. Of the 5 scenarios obtained, it can be observed that the test period for assessing feed efficiency (FE) with greater reliability in predicting the phenotypes of ADG and AMLW is 70 days with weighing at intervals of 14 days. However, the test period for AE can be reduced to 56 days with weighings and intervals of 14 days without affecting the reliability of the predictions of the ADG and AMLW of Senepol cattle.