Behavior and productive indicators for broiler chickens: is environmental enrichment always positive?

• Autor(a) principal: Lourenço da Silva, Marconi Italo [UNESP]
• Data de Publicação: 2023
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/250449
• topic: Affective states; behavior; cognition; spondylolisthesis; poultry; avicultura; comportamento; cognição; espondilolistese; estados afetivos; performance

With the consensus that animals are sentient beings, research on animal welfare is focused on the individual and its experiences. Two experiments were conducted, the objective of Exp. 1 was to evaluate the use of environmental enrichment on the productivity, behavior, and prevalence of spondylolisthesis in fast-growing broilers. In Exp. 2, the objective was to develop a judgment bias test (JBT) for slow-growing broilers, using the social aspects of the species, to assess the effects of fear, anxiety, and chronic stress and to measure the affective states of the broilers. In Exp. 1, 2400 one-day-old, male, Ross® AP95 chicks were used. The animals were allocated into 4 treatments distributed in a randomized experimental design with 4 replications each. The treatments were: control (C) - environment similar to the commercial one without enrichment; environments enriched with hay (HB), step platforms (SP), or laser lights (LL). In Exp. 2, 600 one-day-old, male, Hubbard Redbro chicks were used. The animals were allocated into 2 treatments distributed in a randomized block design, with 6 replications each. Treatments were: low complexity, environment similar to commercial settings, or high complexity, a combination of permanent and temporary enrichments. In Exp. 1, when raised with access to SP and LL, there was a lower frequency of subclinical spondylolisthesis when compared to chickens raised without enrichment or with access to HB. Chickens with access to SP had a higher wing yield and less abdominal fat compared to the C group. Chickens with LL and HB explored more and rested less than the animals in the C and SP treatments. In Exp. 2, fear, anxiety, and chronic stress did not affect JBT training and testing performance. Chickens approached and pecked more the ambiguous cues near the reward cue than those near the neutral cue. Chickens in the control treatment approached the ambiguous cues faster than chickens in the high complexity treatment, suggesting that they are in more positive affective states. Chickens kept in high-complexity treatment were more stressed. In conclusion, environmental enrichment reduces the prevalence of spondylolisthesis and improves exploratory behavior. The enrichment strategy in Exp. 2 was not suitable for slow-growing broilers.