Growth performance of fattening rabbits as affected by stocking density and added dietary organic acids

An experiment of 3×2 factorial arrangement of treatments was undertaken to investigate the influence of stocking density and dietary supplementation with organic acids on growth performance, carcass characteristics, and some blood parameters of fattening rabbits. A total of 54, 7-week-old New Zealand White × California rabbits were randomly divided into 6 experimental groups, of three replicates of 2, 3 or 4 rabbits each. Two experimental pelleted diets (a basal diet and a 0.4% Salkil-supplemented diet; Salkil is a mixture of formic and propionic acids.) were formulated and used from 7 to 13 weeks of age. The rabbits were individually weighed, kept in battery cages at three stocking densities (8.6, 12.9 and 17.2 rabbits/m2), fed their respective experimental diets and managed similarly up to 13 weeks of age. Criteria of response were the performance of rabbits for growth, feed intake and feed conversion, mortality rate, economic efficiency of feeding, and some carcass traits. Some blood plasma parameters (levels of glucose, total protein, albumin, triglycerides and cholesterol as well as activity of the transaminases: alanine aminotransferase and aspartate aminotransferase) were also determined. The results obtained could be summarized as follows: No deaths of rabbits occurred during the course of this study. Regardless of the effect of dietary supplemental organic acids, growth performance of rabbits was not significantly affected by stocking density during the whole experimental period, whereas means of daily feed intake, daily weight gain and performance index of rabbits insignificantly decreased when stocking density reached 17.2 rabbits/m2. Neither carcass traits nor blood parameters of rabbits, measured herein, was affected by stocking density. Irrespective of the effect of stocking density, added dietary organic acids did not significantly affect growth performance, carcass traits or blood parameters of the experimental rabbits. No significant interaction effects of stocking density and added dietary organic acids were detected for all criteria examined in the present study. Taking the performance of rabbits and economic aspect into account, the results revealed that the maximum rate of cage density (17.2 rabbits/m2) had no adverse effects under the condition of the present experiment during the spring season. The dietary inclusion of Salkil at a level of 0.4% was an extravagance; because it had no positive effects on either growth performance or economic efficiency of rabbit production, under the conditions of the present study.