Assessment of food-based enrichment in collared anteater (Tamandua tetradactyla) by non-invasive monitoring of adrenocortical activity

EGUIZABAL GABINA; PALME R; VILLARREAL DANIEL; DAL BORGO CARLA; DOMINCHIN MF; BUSSO JM

Conferencia; Proceedings of the Conference on "non-invasive monitoring of hormones"; 2012

Captive environments offer few opportunities for foraging or feeding and can negatively affects animal welfare. Measuring adrenocortical activity is a standard approach to evaluate stress and welfare in mammals. This study was conducted to: 1) physiologically validate an 11-oxoaetiocholanolone EIA, measuring faecal cortisol metabolites (FCM) with a 5©¬-3a-ol-11-one structure to monitor adrenocortical activity in collared anteater faeces, and 2) investigate the influence of food-based enrichment on adrenocortical activity. Females (n=3) and males (n=2) were studied at Cordoba Zoo (Argentina). Faeces were individually collected (44 days) during pharmacological tests. The adrenal cortex was stimulated by ACTH (5 IU/kg, i.m., 10th day), then suppressed by dexamethasone (0.1 mg/kg, i.m., 37th day). After steroids were extracted from samples, FCM were measured by EIA. Due to great individual variation in defecation frequency (2-8 faeces per week), measurements were individually pooled in pre-ACTH, post-ACTH, pre-dexa and post-dexa groups. Data were transformed to rank and non-parametric Friedman ANOVA was performed. Faecal cortisol metabolites levels were different among groups (post-ACTH> pre-ACTH and pre-dexa> post-dexa; p<0.0001). Three months later, adrenocortical activity response to enrichment was monitored (three faeces/week) during three 6-week periods. The first period was used as FCM baseline (control); then (2nd period) animals were daily subjected to food-based enrichment (i.e. ants, fruits, yogurt). Finally, regular feeding was again provided. A linear mixed statistical model was applied. No differences were detected on average (3.91¡¾0.35, 3.44¡¾0.22 and 4.51¡¾0.35 ¥ìg/g, respectively). However, the number of FCM peaks/period was significantly reduced by enrichment (p=0.02, F2,6=7.79). Peaks were defined on an individual basis as values that exceeded the control period mean plus 75th-percentile. Overall, results indicate that a non-invasive approach was validated to measure stress responses. This method has enormous potential for investigating different types of enrichment in this South American endemic xenarthra species.