Consistency of individual variation in feeding behaviour and its relationship with performance traits in Nile tilapia Oreochromis niloticus

Feed intake is commonly used as one of the most important performance indicators in fish. However, very little is known about the behavioural processes involved in ingesting food such as meal duration, feeding frequency and latency to start eating. This study aims at the characterization of feeding behaviour in Nile tilapia Oreochromis niloticus in terms of consistency of individual differences over time and correlation with performance traits. Seventy-two individuals were individually housed for 27 days. These fish had three different weight (age) categories: low (initial body weight: 61.32 ± 5.97 g), middle (151.19 ± 4.26 g) and high (265.90 ± 19.13 g), each containing 24 fish. Daily feed intake was recorded per fish. On days 8, 15 and 21 feeding behaviour was assessed by measuring the latency to start feeding (LAT, min), the total feeding time (TFT, min) and the number of feeding acts (NFA). In the end of the experimental period, fish were weighed and individual growth rate and feed efficiency (measured as residual feed intake) determined. Results show that feeding latency and the number of feeding acts have significant repeatability estimates for all weight classes. These estimates were, however, low in magnitude and decreased as the weight class increased. The correlation between the different feeding behaviours showed that individuals that are more active during feeding (higher NFA) on average, start to consume their feed earlier (lower LAT) and for longer periods (higher TFT). The number of feeding acts was significantly correlated with both feed intake and growth in all size classes. The residual feed intake was correlated with feeding latency only in the small weight class. These results showed that individual differences in feeding behaviour have low repeatability estimates and can partly explain differences in performance traits in juveniles of Nile tilapi