K.E. Anderson and P.K. Jenkins of the Department of Poultry Science at North Carolina State University in the US have published the results of their study into the effects of rearing dietary regimen, feeder space and density on egg production, quality and size distribution in two strains of brown egg layers in International Journal of Poultry Science.

Step-up protein (SUP) rearing regimens can reduce feed consumption (FC) and body weight (BW), while still resulting in pullets with equal or superior egg production and egg mass to pullets grown on a step-down protein (SDP) programme, the researchers explain.

Egg weight has been reduced due to SUP programmes, presumably due to the reduced BW at sexual maturity. Because BW is reduced by SUP regimens and a slight lowering of FC, BW and egg weight (EW) may be economically advantageous. Therefore, the objective of this experiment was to evaluate the impact of SUP regimens on brown-egg layer rearing programme on subsequent productivity and the effect of feeder space and density on performance.

Two brown-egg strains, Hy-Line Brown (HB) and the H&N 'Brown Nick' (BN) were grown on three different dietary regimens, i.e. a 'normal' SDP regimen, a SUP regimen: low energy starter for nine weeks (SUP9) and a SUP regimen: low energy starter for 12 weeks (SUP12).

The SUP9 and SUP12 feeding regimens resulted in significantly lower BW and feed conversion and shorter sternum length than the SDP regimen.

Egg production was not significantly different among the three regimens but feed conversion was lower while livability was highest in the SUP12 hens.

Feeder space of 13.6cm resulted in poorer feed conversion for the SUP12-reared hens.

Density per hen of 482 square centimetres resulted in significantly improved egg production characteristics, such as 37 more eggs per hen and an 8.1 per cent improvement in flock livability.

Only density affected egg income and feed costs and in both egg income and feed costs were higher in hens kept at 482 square centimetres were $2.39 and $0.21, respectively.

The researchers said that the apparent differences shown in this study appear to relate primarily to strain differences and housing density. This study indicates that a SUP low-protein, low-energy starter diets could be used as part of the rearing dietary regimen with reduced body weights without negative carry-over effects into the laying period.

Rearing pullets did not result in a reduced economic return in the laying period, where providing hens a lower density environment increased the per-hen income, concluded Anderson and Jenkins.

Reference

Anderson K.E. and P.K. Jenkins. 2011. Effect of rearing dietary regimen, feeder space and density on egg production, quality and size distribution in two strains of brown egg layers. International Journal of Poultry Science 10(3): 169-175.

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April 2011