Comparison of the Cornell and Bio-mittent reduced lighting programmes for laying hens.

The Cornell (8L:10D:2L:4D) and (Ralston Purina) Biomittent lighting programmes were applied to a commercial strain of White Leghorn laying hens from 20 to 64 weeks of age. 2. The egg production of hens exposed to the Cornell lighting was reduced compared to the Bio-mittent programme. 3. Food consumption was less and efficiency of utilisation significantly improved for the Cornell programme during phase I (20 to 36 weeks) of the study. Significant differences were not observed during phase II (37 to 64 weeks) or for the whole cycle (20 to 64 weeks). 4. Body weights were significantly greater for hens exposed to the Bio-mittent programme during both phases I and II. 5. Egg weights, egg mass and egg weight distributions were not different for hens exposed to the 2 programmes. 6. Food costs and the margin of income over food costs were significantly in favour of the Cornell programme during phase I. However, differences for phase II and the complete cycle were not significant. 7. The Bio-mittent programme offered a computed advantage of 14.4% fewer hours of light usage compared to the Cornell programme.