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Abstract
Two experiments with caged layers lasting from 20–80 weeks of age were carried out. In two battery blocks a semi-choice feeding system (SCF) was studied using flat chain feeder circuits of 35 m and mechanised devices for feeding restricted amounts of concentrate (C) combined with free access of a whole grain-crushed peas mixture (GP). In another block free access choice feeding (CF) of C and GP was carried out in split troughs. SCF and CF were compared with one or two blocks of birds fed a conventional all mash meal (CAM). Expt. 1 totally involved 3 168 and Expt. 2 2 496 Lohmann Selected Leghorns housed in the cages at 18 weeks of age. The calculated content of the CAM diet was 11.6 MJ ME/kg, 15.7% crude protein, 0.77% lysine and 3.5% calcium. A calculated C/GP ratio of 16/84% corresponded to a diet with 11.0 MJ ME/kg, 14.9% crude protein, 0.72% lysine and 3.5% calcium. The restricted amounts of C given were corrected for the 5.6% lower metabolizable energy content of the calculated SCF diet compared to the CAM diet. Production, intakes of feed and nutrients, mortality, plumage condition and egg quality traits were studied.
Due to significantly heavier eggs, both CF and SCF gave a higher henday production than CAM. Production as kg of egg mass/hen housed (hh) was higher in CF than in CAM and SCF. However, higher mortality in SCF implied no significant difference in egg mass/hh compared to CAM. Feed consumption and feed conversion ratio were higher in CF and SCF as was live weight in CF. Shell quality traits were significantly poorer for SCF compared to CF and CAM. Yolk colour was stronger in CF but there were no significant differences in Haugh units, albumen height or frequencies of blood and meat spots. In a parallel study, the SCF system was studied on a practical farm basis in circuits of 120 m with similar effects as in the present trial. The methods studied may well be economically superior to CAM feeding but the prices of concentrate and home-grown grain in relation to purchased all mash meal are essential, as well as the price of eggs. SCF and CF feeding techniques may be economically favourable to farmers with access to inexpensive cereals and peas and a suitable concentrate.