Investigation into the effect of “day one weight” on bird weight gain of ISA 257 table birds within the Sheepdrove Organic Farm organic silvo-poultry system

Summary

This report summarises the results of a preliminary trial undertaken to investigate the effect of day one chick weight on weight gain and final weight.
The objectives of the trial were to ascertain the range in weights of day old chicks brought on to the farm and establish if any low or high weights were impacting on the weight gain and final weight of the birds.
A sub-sample of the brooder intake of birds was weighed on arrival and marked in accordance with their weight. Marked birds were caught and re-marked weekly.
At week four, prior to the move of the birds to the field sheds, the marked birds were caught weighed and re-marked. It was at this point that the trial was abandoned as, of the 150 birds marked at the start of the trial period, only 48 birds were recovered for re-weighing, despite weekly re-marking.
Despite this, preliminary findings suggest that birds with low weight (below target weight) fail to perform and gain weight as well as birds that were heavier on day one.
However, as discussed, these findings are based on a limited data set so further investigation needs to be undertaken to confirm this finding. Future trials should also investigate whether this trend of lower weight gain for birds that start at a lighter weight carries through to end weight.