Evaluation of raw rock phosphate as substitute for bone meal in diet of laying hens

Abstract

Experiment was conducted to determine the optimal replacement level of Raw Rock Phosphate (RRP) for bone meal in layers diet. A total of 144, 55 week-old shavers X Hubbard cross-strain laying hens were used for the study. Triplicate groups of 12 hens per  replicate were placed on four test diets containing 0, 1, 1.5 and 2% RRP which contributed 0, 350, 525 and 700 mg/kg fluorine (F) in the diets respectively. Dietary RRP up to 2% had no significant (P>0.05) effects on egg production, feed intake, fed conversion and body weight of birds. Mortality was not related to dietary RRP levels. Egg weight, interior quality and shell quality of eggs were not affected by the different dietary treatments. Birds on 1% RRP diet produced egg shell with lower percent calcium (29.24%) than other group. RRP levels in all the groups did not affect phosphorus contents in egg shell. Hens feed on 2% dietary RRP produced eggs containing up to 0.398 mg/kg F and 0.382 mg/kg F in yolk and albumen respectively compared with control groups (0.307 mg/kg F in the yolk and 0.282 mg/kg F in the albumen). Shell fluorine content increased with increasing levels of RRP in diets. It was found from this study that 2% RRP could replace 2% of bone meal and support good egg production in laying hens.

Key words: Raw rock phosphate, substitute, bone meal, laying hens