K.E. Anderson of the Department of Poultry Science at North Carolina State University has published a paper in International Journal of Poultry Science on his work to examine the effects of different feeding levels during rearing for two layer strains.

This study consisted of; two strains of brown-egg pullets, the Hy-Line (HB) and H&N (BN) Brown were raised on three different dietary regimens resulting in a 2×3 factorial design. The three different regimens were a standard Step-down Protein Regimen (SDP) comprised of a 20 per cent CP Starter, 0-6 week, 18 per cent CP Grower 1, 7-12 week and 16 per cent CP Grower 2, 13-18 week; a Step-up Protein Regimen (SUP9) comprised of a 12 per cent CP Starter, 0-9 week, 16 per cent CP Grower 2, 10-16 week and 18 per cent CP Grower 1, 17-18 week and a Step-up Protein Regimen (SUP12) comprised of a 12 per cent CP Starter, 0-12 week, 16 per cent CP Grower 2, 13-16 week and 18 per cent CP Grower 1, 17-18 week.

The pullets were housed in an environmentally controlled rearing facility with tri-deck battery cages. Feed consumption and body weights were measured bi-weekly and mortality was recorded daily.

At 17 weeks of age, a sample of 20 pullets from each strain and regimen combination were randomly selected and brought to the laboratory for body composition analysis.

At 18 weeks, the HB and BN strains only differed in livability with the HB having a 4.2 per cent greater (p<0.05) liveability than the BN pullets. There was a stepwise reduction (p<0.05) in total protein intake from the SDP, SUP9 and SUP12, however, energy, calcium, phosphorus and lysine consumption were comparable.

The SUP9 and SUP12 feeding regimens resulted in significantly (p<0.05) lower body weight than the SDP regimen pullets.

The SUP12 regimen significantly reduced sternum length below that obtained with the SDP or SUP9 programme 11.0 versus 11.2 and 11.3cm, respectively.

Tibial breaking strength was not affected by strain or regimen.

This study shows that pullets reared on SUP regimens would have lower body weights with few differences in body composition percentages. This indicates that reduced dietary protein and energy would result in smaller pullets with comparable body composition.

Reference

Anderson K.E. 2010. Effects of dietary regimens and brown-egg pullet strain on growth and development. International Journal of Poultry Science 9 (3): 205-211.

Further Reading

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