Comparison of the nutritive value for laying hens of diets containing azolla ( Azolla pinnata) based on formulation using digestible protein and digestible amino acid versus total protein and total amino acid

Abstract

Azolla ( Azolla pinnata) was assessed for nutrient content and feeding value in laying hen diets. Proximate analysis, together with the estimates of digestible protein, ADF, NDF and metabolizable energy indicated that it was a fair source of plant protein (285.4 g kg −1) with a digestible protein value of 219.8 g kg −1 and a metabolizable energy value of 7.59 MJ kg −1 (906 g kg −1 DM). The feeding value of azolla in laying hens was studied in two feeding trials of 16 and 8 weeks duration, respectively. Azolla meal was included at a level of 50 or 100 g kg −1 diet at the expense of sesame meal in diets formulated on a total protein and total amino acid, or digestible protein and digestible amino acid basis (Trial 1). In Trial 2, 150 and 200 g kg −1 azolla meal was included in diets formulated using a total protein and total amino acid, or digestible protein and digestible amino acid basis. L-lysine HCl and DL-methionine were added to the diets formulated using digestible nutrients to adjust the digestible lysine and methionine contents to those in the wheat sesame meal based control diet. It was found that azolla meal could replace sesame meal on a digestible protein and digestible amino acid basis up to 200 g kg −1 diet with egg production as the parameter, while it could replace only up to 150 g kg −1 sesame meal in the diet based on total protein and total amino acids. Egg mass output and feed conversion ratio were significantly better with up to 200 g kg −1 azolla meal in the diet when included on a digestible protein and digestible amino acid basis but not when the diets were formulated on a total protein and total amino acid basis. Feeding azolla on a digestible protein and digestible amino acid basis maintained or improved protein efficiency. Feeding azolla on a total or digestible nutrient basis had no affect on egg quality except egg size and yolk colour. Egg size improved when the diets were formulated on a digestible protein and digestible amino acid basis. Yolk colour was significantly improved with increasing levels of azolla meal and a longer period of feeding.