Effect of ambient temperature on the productive and carcass traits o growing rabbits divergently selected for body fat content

Rabbits are particularly sensitive to heat stress which can affect productive performance, with rabbit breed/line possibly playing a role on the response to this condition. The study aimed at evaluating the effect of different ambient temperatures on the live performance and carcass traits of growing rabbits divergently selected for total body fat content. The two genetic lines (Lean and Fat) were selected based on the total body fat content estimated by computer tomography during live generations. From birth to slaughter (13 weeks of age), the rabbits were housed in two rooms where the temperature was controlled with air conditioners: in the control room the average ambient temperature was 20 degrees C and in the high temperature room it was 28 degrees C. After weaning (35 d), 60 Lean and 60 Fat rabbits/room were housed by two in wire-mesh cages and fed ad libitum with commercial pellets. The BW and feed intake (FI) were measured at 5, 7, 9, 11 and 13 weeks of age to calculate the daily weight gain (DWG) and feed conversion ratio (FCR). Mortality was recorded daily. At the end of the experiment, rabbits were slaughtered and carcass traits were measured. Mortality was independent of temperature and line. The temperature significantly influenced the Fl, DWG, BW and the fat deposits: they were lower at higher ambient temperature. The effect of temperature differed according to the rabbits' total body fat content. At control temperature, the F1 (165 vs 155 g/day; P < 0.05) and FCR (4.67 vs 4.31; P < 0.05) were higher in Fat rabbits, which also had more perirenal (36.2 vs 23.1 g; P < 0.05) and scapular fat (10.8 vs 7.1 g: P < 0.05). At high temperature, no differences in fat depots (14.5 vs 9.8 g; 5.3 vs 3.5 g) were found between the two lines. It can be concluded that temperature x genetic line interaction had an important role in productive and carcass traits, as the effect of temperature differs between Lean and Fat rabbits. (C) 2020 The Authors. Published by Elsevier Inc. on behalf of The Animal Consortium.

Automated summary

The study found that different ambient temperatures have varying effects on rabbits selected for different total body fat contents, with higher temperatures negatively impacting growth performance and carcass traits. Temperature and genetic line interaction plays an important role in determining productive and carcass traits in rabbits.