EFFECT OF VERMICULITE ON PRODUCTIVE PERFORMANCE OF WHITE LEGHORN HENS IN A CONTROLLED FEEDING SYSTEM

Feeding ad libitum of laying hens was compared with controlled feeding in terms of rate of lay, feed efficiency, body weight gain, mortality, egg size and quality. Birds were assigned to four treatment groups: (A) basal diet ad libitum: (B) 5% less feed than the standard requirement; (C) and (D) restricted as for Treatment B, but with 4% and 6% of the basal diet, respectively, replaced with vermiculite. The treatments were applied for 1 year from 151 to 515 days of age. Body weight gain of restricted birds (Groups B, C and D) was less than that of Group A, but the latter group attained 50% egg production 3-9 days later than the restricted groups. Egg production per 100 hen-days was 67.2, 68.2, 71.0 and 69.1, and egg mass output was 3.74 kg, 3.86 kg, 4.10 kg and 3.97 kg for Groups A, B, C and D, respectively. Group C laid significantly more (P < 0.05) eggs than Groups A and B. All restricted feeding groups produced fewer abnormal eggs and required 610-870 g less feed per kilogram of egg production. The vermiculite groups (C and D) ate 21-22% less feed than Group A (P < 0.05). The best results for egg production and feed utilization were from Group C in which 4% of the basal diet was replaced with vermiculite.