Methods for identifying stress caused by fasting in commercial laying hens/Metodologias para indicar estresse causado por jejum em poedeiras comerciais

• Published in: Ciência rural 2024-08, Vol.54 (8), p.1
• Main Authors: Cesar, Paula Horatio, Bedin, Aline Felix Schneider, Mayer, Jaqueline Kunhen, de Souza, Cleverson, Gewehr, Clovis Eliseu
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20220587

Plasma corticosterone concentration (CORT), heterophih:lymphocyte ratio (H:L), catalase activity (CAT), total glutathione concentration (GSH), and thiobarbituric acid reactive substance levels (TBARS) were evaluated in 48 Hy-Line Brown laying hens, at 79 weeks of age, after being fasted for 10 consecutive days. Blood was collected on days zero, two, four, six, eight, and 10 of fasting, and a completely randomized design was adopted, with eight replicates on each day of collection, with each bird being an experimental unit. The time of maximum stress was determined for each method, using the polynomial regression analysis. The Pearson correlation analysis was also performed to determine whether the methods were interchangeable. CORT and GSH concentrations indicated that the time of maximum stress occurred at 4.3 days of fasting, whereas, the H:L and CAT activity indicated that the time of maximum stress occurred at 10 days of fasting. The malondialdehyde concentration detected by the TBARS method was highest at day zero and lowest at day 5.5 of fasting, but this method was not a reliable measure of stress. The low Pearson correlation coefficients observed among the methods made it impossible to designate only one of the tested methods as a replacement for the others, to measure the stress in laying hens during fasting. Keywords: corticosterone, fasting, heterophil:lymphocyte ratio, oxidative stress. A concentração de corticosterona plasmática - CORT, relação heterófilo:linfócito - H:L, atividade enzima catalase - CAT, concentração glutationa total - GSH e níveis de substâncias reativas ao ácido tiobarbitúrico - TBARS foram avaliadas em 48 poedeiras Hy Line Brown, 79 semanas de idade, submetidas ao jejum alimentar por 10 dias consecutivos. Coletou-se sangue no dia zero, dois, quatro, seis, oito e 10 do período de jejum alimentar, adotando-se um delineamento inteiramente casualizado, com oito repetições em cada dia de coleta, sendo cada ave uma unidade experimental. Através da análise da regressão polinomial determinou-se o momento de máximo estresse para cada metodologia. Realizou-se análise de correlação de Pearson para determinar se pode haver substituição entre os métodos. A CORT e GSH apresentaram o momento de máximo estresse aos 4,3 dias de jejum alimentar, enquanto que H:L e CAT aos 10 dias. TBARS apresentou maior concentração de malondialdeído no dia zero de jejum alimentar e a menor aos 5,5 dias, não sendo uma metodologia confiável para medir o estre