Organic broilers need more methionine
The Animal Sciences Group from
Wageningen University published a new report covering the results of a
performance trial to determine the effect of dietary crude fibre (CF) and
methionine contents on performance and slaughter quality in organic broilers.
In organic diets, an increase of the amount of organic produced raw
materials seems to result in a higher crude fibre and a lower methionine
concentration. Until now, the effects of these nutritional changes on
performance and slaughter quality of organic broilers are unclear. Possible
interaction effects with different strains of slow growing broilers are also
unknown. Wageningen University researchers therefore set up an experiment to be
able to develop 100% organic diets that not negatively affect performance and
welfare of broilers.
Decreased growth and feed intake
From the study with 1680 slow growing broilers (1 - 70 days of age) it can
be concluded that an increase of the dietary crude fibre content will decrease
growth rate and feed intake of the birds. The effect of crude fibre content on
feed conversion ratio, however, depends on the age of the bird.
Over the first 50 days, an increase of the crude fibre content results in a
reduced feed conversion ratio, whereas this increase will improve feed
conversion ratio over the last 20 days of the growth period. Over the whole
growth period, crude fibre content of the diet do no affect feed conversion
ratio. A reduction of the dietary methionine concentration results in a lower
final weight of the broilers.
Slaughter results are not affected by dietary crude fibre and methionine
concentrations, but they are affected by strain. Nearly all slaughter quality
parameters were reduced in Master Gris compared to JA957 broilers.
Therefore, Master Gris birds seem less appropriate for organic broiler
husbandry. Finally, it was concluded that dietary crude fibre and methionine
concentrations should be kept on the standard levels to maintain performance of
broilers that are fed 100% organic diets.
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