Effect of conjugated linoleic acid on Cyprinus carpio var. Jian regarding growth, immunity, and disease resistance to Aeromonas hydrophila.

The present study was performed to investigate the effect of dietary conjugated linoleic acid (CLA) on the growth performance, immune parameters and disease resistance to Aeromonas hydrophila of juvenile Jian carp. A total of 900 juvenile Jian carp (10.71 +/- 0.02 g) were randomly allocated into six groups of each three replicates, feeding isonitrogenous (35% crude protein) and isolipidic (7.8% crude fat) diets containing graded amounts of CLA (0, 0.5, 0.8, 1.4, 1.7, and 2.0%) for 60 days. After a 60-day growth test, a challenge trial was conducted by intraperitoneal injection of Aeromonas hydrophila to determine the effect of CLA on disease resistance of juvenile Jian carp. The results showed that diets incorporated with a proportion of up to 2.0% CLA without effect on weight gain, feed intake, and feed conversion ratio, but improved immune parameters and disease resistance of juvenile Jian carp. The dietary CLA level of optimal disease resistance to Aeromonas hydrophila was estimated to be 1.7% in juvenile Jian carp using broken-line analysis.