Effects of Cage Stocking Density on Feeding Behaviors of Group-Housed Laying Hens

摘要

Quantitative measurement of animal welfare continues to be a challenging task for both the animal agriculture industry and the scientific community. Characterization of animal feeding behavior provides a comparative elucidation of the animal’s behavioral deviation from its norms and thus carries implications for its welfare. This study examines the effects of cage stocking density (348, 387, 426, and 465 cm2; or 54, 60, 66, and 72 in.2 cage floor space per hen) on feeding behavior of W-36 White Leghorn laying hens kept in groups of six hens. The study employed a specialized instrumentation system and computational algorithm. The results revealed no significant difference among the stocking densities under thermoneutral conditions with regard to the following: daily feed intake (97 to 101 g/hen, p = 0.37), daily feeding time per hen (3.0 to 4.0 h/day, p = 0.32), number of meals ingested per day per cage (117 to 181 meals/day, p = 0.18), meal size (1.6 to 2.6 g/meal-hen, p = 0.09), meal duration (174 to 258 s/meal, p = 0.40), ingestion rate (0.47 to 0.77 g/min-hen, p = 0.06), and number of hens feeding per meal (1.9 to 2.0 hens/meal, p = 0.72). However, there was a trend that hens under the 465 cm2 (72 in.2) stocking density displayed a greater meal size and ingestion rate. A field-scale study further investigating the effects of conventional vs. newly recommended (and voluntarily adopted) stocking densities on commercial egg layers seems warranted.