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Stocking Density During Pullet Rearing Evaluated By Purdue University


Egg-NewsDr. Darrin M. Karcher of Purdue University recently completed a study on pullet rearing funded by the U.S. Poultry Foundation as Project F083.  In the first study, brown- and white-feathered strain Lohmann pullets were reared at either 670 cm2/bird (104 inch2/bird) or low density 1,352 cm2/bird.(210 inch2/bird)  There was no difference in uniformity, weight at 16 weeks or the subjective evaluation of keel integrity or feet.  In the brown-feathered strain, high stocking density resulted in decreased uniformity and lower feather covering.  Low stocking density improved feed conversion.  White-feathered pullets subjected to high density were more uniform and feather coverage than this strain reared at low density.


A second trial compared three stocking densities ranging from 1,247 cm2/bird (195 inch2/bird) through a medium allowance of 519 cm2/bird (80 inch2/bird) and high density 155 cm2/bird (24 inch2/bird).  High stocking density resulted in “poorer feather condition” but enhanced feed conversion ratio.  This trial incorporated two feeder space allocations.  Irrespective of density, reducing feeder space depressed feed conversion ratio.


The results failed to identify any outcome measures of stress and welfare attributable to stocking density, irrespective of feeder space allocation or density. Pullets were essentially similar with respect to practical parameters.  It is hoped that further data will be released relating to the subsequent age at onset of production and peak, egg weight with hen week production, case weight, feed conversion and livability data through at least 50 weeks of age.


The trials conducted by Dr. Karcher, and his colleagues are important since they provide quantifiable, scientific evaluation of growth and evaluation of stress that are important in establishing standards.  Clearly, the financial implications of rearing pullets at either 670 cm2/bird or 1,352 cm2/bird are self-evident. Standards imposed by certifiers of animal welfare based on subjective evaluation by panels should be justified by appropriate data.