Nutritional requirements, behavior, animal temperament, feed efficiency, metabolic parameters, carcass and meat quality from buffaloes in tropical conditions

Abstract

There is an increasing interest in the use of residual feed intake (RFI) as a tool for measuring feed efficiency in cattle and sheep on growth. However, the biological basis of differences in RFI from buffaloes is still unknown. The aim of this unpublished research is to evaluate feed efficiency and its phenotypic correlations with metabolic parameters, food digestion, behavior, and carcass traits in buffalo. The experimental design will be completely randomized. A total of four experiments will be carried out for 4 years (one each year). Data will be analyzed and published the year after the last experiment. In the Experiment I (Year #1; duration: 231 days; composed of three periods) 75 buffalo bulls (25 animals of each genetic group: Jafarabadi, Mediterranean and Murrah) born and weaned in 2013, average weight and age of 180 kg and 210 days, respectively, will be used. In the first period will be determine intake and evaluate individual intake behavior (GrowSafe system) of animals during a trial period of 112 days. In the second period a 7-day digestibility assay will be performed. In the third period (119 days) 4 animals of each genetic group (12 animals in total) will be slaughtered at the beginning of this trial period to determine initial body composition (reference group). The remaining 63 animals will be classified according to slaughter weight (420, 480, 540 kg) to determine nutritional requirements of each genetic group. Ultrasound evaluation, body measurements, body condition score, and animal temperament will be carried out. The weighing will be performed daily by automatic scales coupled to sensors (DeLaval System). Blood samples will be collected for evaluation of metabolic and behavioral parameters, and identification of molecular markers for performance. Measurements on carcass (backfat thickness and loin eye area) will be performed, and samples of HH section and LM will be collected to evaluate meat quality traits. In the Experiment II (Year #2; duration: 231 days; composed of three periods) two first periods will be the same as in Experiment 1; however, in the third period the animals will be classified according to RFI determined in the first period. One hundred twenty buffalo bulls (40 of each genetic group) will be used. The same data collection used in the "Experiment I" will be performed to assure the reliability of results. In Experiment III (Year #3; duration: until animals reach the slaughter weight pre-determined in experiments I and II) aims to validate the results of experiments I and II through 3 different production systems: 1-Pasture+Feedlot; 2-Pasture with supplementation; and 3-Feedlot. Diets will be formulated based on the results of nutritional requirements obtained in the two prior experiments (years 1 and 2). One hundred eight animals (36 of each genetic group) will be divided into 3 production systems (12 animals of each genetic group for each production system). Ultrasound evaluation, body measurements, body condition score, and animal temperament will be carried out. The weighing will be carried out every 28 days (in animals on pasture) or daily by automatic scales coupled to sensors (in animals on feedlot). Blood samples will be collected for evaluation of metabolic and behavioral parameters, and identification of molecular markers for performance. Measurements and sample collection will be performed as in the two prior experiments (years 1 and 2). Experiment IV (Year #4; duration: until animals reach the slaughter weight pre-determined in experiments I and II) will be similar to "Experiment III". Also, the same data collection will be performed to assure the reliability of results. Data will be analyzed with REG, MIXED, and CORR procedures of SAS (SAS Institute Inc., Cary, NC, USA), submitted to analysis of variance and comparison of means by Student's test of Newman Keuls at 5% probability. (AU)