J. Kilburn et Hm. Edwards, The response of broilers to the feeding of mash or pelleted diets containing maize of varying particle sizes, BR POULT SC, 42(4), 2001, pp. 484-492
1. The effects of maize particle size and steam pelleting on growth and nut
rient utilisation were studied with broiler chicks.
2. The presence or absence of 10 mug/kg of 1, 25 dihydroxycholecalciferol i
n diets adequate or deficient in phosphorus was also investigated. Food eff
iciency was superior with the fine maize diets but calcium retention and ph
ytate phosphorus retention were greatest with the coarse maize diets. Pelle
ting improved food efficiency and growth in both experiments while phytate
phosphorus utilisation was decreased.
3. Addition of 1,25-dihydroxycholecalciferol to the diet increased 16-d bod
y weight, bone ash, plasma dialysable phosphorus and retentions of total ph
osphorus and phytate phosphorus while decreasing phosphorus deficiency rick
ets and tibial dyschondroplasia.
4. There were significant interactions between maize particle size and food
form. The improvement in calcium retention observed with the coarse maize
diets was reduced when the diets were pelleted. When fed as a mash, coarse
maize diets resulted in increased plasma dialysable phosphorus levels but w
hen the diet was pelleted this response was eliminated.
5. There was also a significant interaction between particle size and phosp
horus concentration in that chicks given diets deficient in phosphorus had
improved bone ash when fed coarse maize as compared to fine maize. However,
this response was eliminated when the diets were adequate in phosphorus.
6. In one experiment, fine maize diets had higher metabolisable energy valu
es and there was a significant interaction between maize particle size and
food form as pelleting improved the metabolisable energy value of coarse ma
ize diets but not fine maize diets. In another experiment only pelleting of
the factors studied improved the metabolisable energy value of the diets.