Effects of edible environmental enrichments during the rearing and laying period in a littered aviary – Part 2: Physical development of pullets and performance, egg quality and carcass composition in laying hens

Abstract Feather pecking and cannibalism are two major problems in laying hens’ husbandry. Although additional environmental enrichment materials’ (EM) supply is thought to lessen these problems, consistent evidences are lacking. This study examined the effects of EM supply (pecking stones and alfalfa bales) on biological performance, carcass composition and animal losses in a littered housing system. 2,000 brown-egg and 2,000 white-egg layer hen pullets of the genetic strains Lohmann Brown classic (LB) and Lohmann Selected Leghorn classic (LSL), respectively, were reared separately in a 16 compartments’ aviary system until week 18. 1,320 remaining laying hens were then transferred to a 44 compartments’ laying stable (weeks 19 to 48). Both strains were tested under four treatment variants (n=150-180 per strain and per variant): V1- no EM over the entire study period; V2- rearing period with and laying period without EM; V3- rearing period without and laying period with EM; V4- EM over the entire study period. Development, performance, egg quality, feed intake, EM consumption, animal losses, carcass composition, and economic traits were collected. EM supply during rearing (V2 and V4, both strains) was found to globally increase hens’ relative gizzard mass (P=0.036), but also the cracked eggs’ percentage (compared to V3; P=0.008), and to decrease the body mass in weeks 6 (P=0.023) and 8 (P=0.023) and the uniformity in week 16 (P=0.011). EM provision during the laying period (V3 and V4, both strains) increased egg weights (P=0.028) and the mean body mass (P=0.036), however, continuous provision of EM (V4, both strains) increased the floor eggs’ percentage (P=0.019). The EM supply did not affect mortality, loss of production days, losses due to skin and toe cannibalism, or the income over feed costs. However, the income over feed and enrichment costs of V1 hens was higher by 0.55 €/hen compared to V4 hens (P=0.022). Therefore, EM supply cannot be recommended as a measure to increase laying performance and reduce animal losses, but its positive effects on animal welfare should be considered.