Effects of dietary minerals on postmolt performance of laying hens

Abstract

Four hundred and fifty Single Comb White Leghorn commercial layers (66-67 weeks-old) were housed 2 birds per cage for the molting procedure. The hens were divided into 5 treatment groups with 90 layers per treatment and 30 layers in each replicate per treatment group following completely randomized design. During molt period (2 Weeks), experimental birds were randomly assigned to five-treatment groups viz., A (15 ppm copper sulphate), B (20 ppm zinc oxide), C (20 ppm aluminium oxide), D (balanced layer diet without added minerals) and E (without induced molting as control). The birds in groups A, B, C and D were offered respective experimental diets at the rate of 30 g/bird except bird's in-group E (ad libitum) and lighting program was followed as 12L: 12D. During rest period (3 Weeks) the birds in groups A, B, C and D were given respective experimental diet at the rate of 50 g/bird for first 2 weeks of the rest period. During 3rd week of rest period the birds in groups A, B, C and D were given experimental diets at the rate of 60 g/bird and were placed on lighting program of 14L:10D. During production phase, the birds of all groups were fed a balanced layer diet (ad libitum) and birds were placed again on lighting program of 16L:8D. The results showed that the birds fed diets A, B and C showed greater (p<0.05) percentages of body mass loss than those fed the diet D. The birds fed diet E (Full feed-non molted group) exhibited the least amount of body mass loss when compared with all other treatments of molted hens. Un-supplemented mineral group and un-molted hens had higher (p<0.05) ovarian weights than hens on all other molted treatments. No significant differences (p>0.05) in ovarian weights were found among minerals supplemented groups A, B and C. The non-molted birds (group E) exhibited the greatest (p<0.05) feed intake over the 2 weeks molt whereas birds on minerals supplemented diets ate the least (p<0.05) feed. On average non-molted hens fed a balanced layer diet and molted hens fed without minerals diet had lower (p<0.05) egg production when compared with molted hens fed mineral added diets after 20 weeks post molt. However, molted hens fed without minerals diet had significantly higher egg production than that of non-molted hens fed a balanced layer diet. Egg shell quality and Haugh unit score improved (p<0.05) in molted hens compared to non-molted hens. Based on the results of this study, mineral feeding appears to be the best alternative to without mineral feeding in molting methods and yield comparable results.