Document type: meta-analysis published in Research in Veterinary Science
Authors: Henrique Sonda Gallina, Maria Eugênia Andrighetto Canozzi, Pietra Viertel Molinari, Juahil Martins de Oliveira Júnior, Ivan Bianchi, Fabiana Moreira, Débora Cristina Olsson, Paula Gabriela da Silva Pires, Javier Sanchez, Vanessa Peripolli
Preview: The objective of this study was to evaluate the effects of beak trimming-using a hot blade or infrared radiation-on mortality, egg production, feather pecking, and corticosterone levels in laying hens, using systematic review-meta-analysis (SR-MA) methodology. A total of 1775 citations were identified. The number of birds evaluated was 76 for corticosterone, 6172 for mortality, and 5460 for egg production. Twenty-three articles were assessed, with 13 included in the quantitative synthesis. Birds subjected to hot blade trimming showed a lower probability of mortality (Relative Risk - RR = 0.47; p = 0.087) compared to untrimmed birds, with high heterogeneity (I2 = 94.64 %). Both shallow (≤ 5 mm; RR = 0.64; p ≤ 0.0001) and deep (≥ 5 mm; RR = 0.02; p ≤ 0.0001) beak trimming reduced mortality compared to untrimmed birds. No consistent evidence was found linking beak trimming to changes in egg production or corticosterone levels; however, due to the low number of studies and methodological variability, these findings should be interpreted with caution. Infrared beak trimming appears to be a promising, less invasive alternative, showing potential welfare benefits without compromising performance. Further standardized research is needed to strengthen conclusions, especially on stress-related physiological responses.
