Welfare Indicators in Tilapia: An Epidemiological Approach

Abstract

Interest and concern about rearing methods and their impact on animal welfare have increased. Production evaluation is population-based, and animal welfare analysis should be similar. In fish, the most common welfare indicators are gill state, fin damage, and body condition. The objective of this study was to evaluate the feeding rate effect on the welfare indicators of Oreochromis niloticus using an epidemiological approach. Five growth stages (from 1.2 to 360 g) were studied using four feeding rates as treatments: underfeeding (80%), recommended feeding (100%), and two levels of overfeeding (120% and 140%). The evaluated welfare indicators include the presence of lesions in different body areas and fins, the decrease in body condition index, and their impact on biomass production. Incidence and relative risk were determined for each indicator. Statistically significant associations were found in the indicators of mortality, weight, body condition (K), and presence of evident damage in the caudal and anal fin in all stages. The results showed that the feed rate directly affects the welfare indicators and production. Mortality, weight reduction, K reduction, and caudal and anal fin damage incidence showed to be relevant indicators in all O. niloticus growing stages. As a result of this study, the epidemiological approach seems to be a valuable tool for production. A risk traffic light method is a proposal that could have great potential, with the suggested limits for WI's concerning the individuals present in the culture pond, allowing progressive evaluation and decision-making to correct risky situations.

Assessment of Tilapia (Oreochromis spp.) Welfare in the Semi-Intensive and Intensive Culture Systems in Thailand

“…The presence and severity of these injuries can indicate inadequate welfare practices and husbandry. Our findings identified tilapia fins and skin as the two primary indicators of external injuries, which is consistent with previous welfare assessments at tilapia farms in Brazil and Mexico [11,12], as well as in other fish species including rainbow trout and salmon [8]. It is crucial to determine the underlying cause of injuries and lesions, such as inappropriate management, as these can indicate poor animal welfare and lead to poor fish health.…”

“…In tilapia, it is essential to incorporate welfare considerations into an assessment protocol to address welfare concerns during tilapia production. In 2022, Flores-García and colleagues evaluated the effects of feeding rates and several welfare indicators to aid in decision making regarding and the evaluation of tilapia production through a color-coding approach inspired by traffic signals and assigned scores to the colours red, yellow, and green [11]. Another study in Brazil revealed that the application of welfare assessments in tilapia can promote sustainable and ethical aquaculture practices that benefit fish health and growth.…”

From egg to slaughter: monitoring the welfare of Nile tilapia, Oreochromis niloticus, throughout their entire life cycle in aquaculture

“…The welfare of any organism is a dynamic state ( 126 , 127 ), and the systems used to monitor it should be flexible enough to adapt to changes in its welfare state ( 17 ). There is also an understanding of the need for protocols to consider the interaction between different indicators ( 119 , 122 , 128 ), providing relevant information about the overall quality of life of the animals ( 129 , 130 ).…”

Biosecurity: Reducing the burden of disease

“…To assess the welfare status of the farmed animals, "operational welfare indicators (OWIs)" are useful practical tools (Flores-García et al, 2022;Noble et al, 2018;Segner et al, 2012). Usually, no single indicators are used, but a series of parameters are measured and integrated.…”