Evaluation of the performance of Hy-Line Brown laying hens fed soybean or soybean-free diets using cage or free-range rearing systems
This study evaluated egg production and quality variables of caged and free-range Hy-Line Brown laying hens fed soybean meal (SBM) and soybean-meal-free (SBMF) diets. Hens were randomly assigned to the same 2 dietary treatments within 3 location blocks. SBM and SBMF diets with equivalent calculated nutrient content were prepared based on Hy-Line Brown rearing guidelines. The SBMF diets utilized cottonseed meal, corn distillers dried grains with solubles, corn gluten meal, and wheat middlings in place of dehulled soybean meal. The experiment was conducted between August 2015 and January of 2016 within the TAMU Poultry Research Center and data analyzed over 6 consecutive 28-day periods. Data were analyzed as a split-plot with rearing systems designated whole plots and diets designated as subplots. Hens reared in the free-range rearing system peaked a couple of wk later than those hens within the more conventional indoor caged system, and cumulative production data were considerably more variable for hens raised in the free-range environment. Cumulative egg production, feed per dozen eggs and feed conversion ratio (g feed/g egg) were 92 ± 1.23 and 86 ± 1.84%, 1.45 ± 0.02 and 1.89 ± 0.05 kg, and 2.14 ± 0.04 and 2.77 ± 0.08 (P < 0.05), respectively, for the caged vs. free-range rearing systems. Cumulative egg weight, feed per dozen eggs, and feed conversion ratio were 59.9 ± 0.59 and 56.5 ± 0.60 g, 1.57 ± 0.04 and 1.77 ± 0.05 kg, and 2.24 ± 0.06 and 2.67 ± 0.08 kg (P < 0.05) for SBM and SBMF diets, respectively. Diet did not affect cumulative egg production (P > 0.05). With respect to egg quality, there were no differences in cumulative albumen height, Haugh unit, or breaking strength, but there was a significant rearing system by diet interaction for shell thickness, with the free-range hens averaging 40.77 ± 0.19 and 39.86 ± 0.31 μm (P < 0.05), respectively, for the hens fed SBM vs. SBMF diets. In conclusion, the results suggested free-range production is more variable than traditional closed-house cage systems based on standard errors, and SBMF diets containing cottonseed meal can be used in both caged and free-range production systems without affecting egg production, although one might see lower egg weights.