Egg Industry - October 2009

PSA review: Science continues to improve production

Presentations on various topics pertaining to egg production and poultry well-being explore industry insights and implications.

The 2009 Poultry Science Associa- tion Meeting included a number of presentations which have direct implications for commercial egg production. The signi;cant papers are reviewed within topic categories.

4 • Industry Egg • October 2009 • www.WATTAgNet.com Welfare

Welfare is a signi;cant issue relating to the design of housing, production management and consumer acceptance. Presentations at the PSA Meeting encompassed rearing, colony vs. conventional cages and nutrient composition in eggs from hens housed in cages compared to range production.

Article 170 – A Comparative Examination of Rearing Parameters for Brown Egg-Type Pullets Grown for Either Range or Cage Production

This presentation is derived from data assembled from the random sample test conducted by Ken Anderson at North Carolina State University. His studies have recently been extended to ;oor-housed ;ocks in both cage-free houses and on pasture. Hy-Line brown pullets were reared using either cages allowing 48 inch2 per pullet or brooded in ;oor pens allowing 1 ft2/pullet with trans-

fer to range at 12 weeks of age. Pullets reared in cages were heavier than pen/ range reared birds by 0.2 lb. Total feed consumed was 13% lower in pen/range reared pullets attributed to foraging after 12 weeks of age. It was noted that pullets must gain familiarity with ranges, roosts and nests and learn foraging behavior prior to onset of production.

Article 174 – A Comparison of Humoral Immune Function in Response to a Killed Newcastle Vaccine Challenge in Caged vs. Free-Range Hy-Line Brown Layers

In an attempt to evaluate stress in hens subjected to either cage or range housing, subjects were injected with an inactivated Newcastle disease emulsion to compare antibody titers as in;uenced by housing system. Caged hens demonstrated a signi;cantly higher level of antibody production compared to free-range hens. Heterophilia (increased ratio of heterophil blood cells to lymphocytes) consistent with higher levels of stress was documented. These ;ndings are consistent with the acknowledged higher mortality in free-range hens compared to ;ocks housed in cages.

Article 246P – Effect of Different Cage-Systems on Laying Hen Welfare

Scientists at the Shandong Agricultural University compared the performance of laying hens in conventional cages with aviaries and furnished cages. Feed conversion ratio was signi;cantly lower in standard tiered cages and egg output was signi;cantly higher than in the alternative non-con;ned systems. There was no difference in either egg production or feed conversion between aviaries and furnished cages. After experiencing fear, the plasma non-esteri;ed fatty acid levels were signi;cantly lower in caged hens compared to alternative systems. It is signi;cant that the study did not evaluate corticosteroid levels or heterophil ratios which are standard measures of stress. Plasma creatine kinase, uric acid, glucose or non-esteri;ed fatty acids which were determined would not generally be regarded as direct indicators of the level of stress. The authors’ conclusion that there is greater stress in conventional cages cannot be supported by either the experimental design or the data obtained.