Number and length of pyloric caeca and their relationship to fat and protein digestibility in rainbow trout

Abstract

An investigation was performed to study the variation in number and length of pyloric caeca and its relation to fat and protein digestibility together with other traits. Eighteen full-sib and 6 sire groups of 2 1 2 - year-old rainbow trout were used. The fish had been reared in sea-water cages for 1 1 2 years and had reached an average body weight of 3 kg. No significant effect was found for any of the 10 sources of variation included in the analysis except for length of intestine which had some effect on fat and protein digestibility. There was a negative phenotypic correlation between number and length of caeca and a positive correlation between fat and protein digestibility. Significant sire effects were found on length of intestine, length of caeca and protein digestibility while no sire effects were found on number of caeca and fat digestibility. It is concluded that variation in number and length of caeca is not of great importance for either fat or protein digestibility in rainbow trout.