Physiological responses to long fasting followed by refeeding in juveniles of pirapitinga, Piaractus brachypomus

Abstract

For many fish species, prolonged fasting is part of their life cycle, as there are seasonal fluctuations in the quantity and quality of food available in their natural habitat. These animals use endogenous reserves during periods of food scarcity and recover when resources become available again. We evaluated the effect of a prolonged fasting period on indicators of body reserve use, growth performance and intestinal integrity of the Amazonian serrasalmid Piaractus brachypomus. We distributed 66 juveniles (68.6 ± 2.2 g) in 11 tanks. The treatment consisted of 30 days fasting followed by 45 days refeeding and the control of 75 days normal feeding with 5 replicates (one tank with six fish). The six individuals in the 11th tank were used for baseline measurements. Blood parameters, muscle lipid concentration, hepatosomatic and mesenteric fat indices, somatic growth parameters and intestinal villi morphology were measured every 15 days. Glucose, triglycerides, cholesterol, total protein, the mesenteric fat and hepatosomatic indices, weight gain, specific growth rate, condition factor and total biomass decreased significantly during fasting compared to the control, but all except body condition recovered during refeeding. The length and perimeter of the intestinal villi was significantly lower during fasting compared to the control. The feeding protocol allowed P. brachypomus to mobilize part of their body reserves during fasting, however, in general, refeeding was sufficient to restore their body needs and growth performance compatible with that of continuously fed animals.

Effects of Prolonged Fasting and Refeeding on Metabolic, Physiological, Tissue, and Growth Performance Adjustments in Colossoma macropomum

“…The prolonged fasting period of 45 days resulted in a general decrease in growth performance, such as the reduction in final length from day 30, as well as the reduction in final weight, weight gain, and specific growth rate after 45 days of fasting. These responses corroborate other studies that also used long fasting periods for other fish species [39][40][41][42]. Furthermore, the 14-day refeeding period promoted greater final weight in the fasted/refed group when compared to the basal group, but this period was not enough for this group to reach the weight, length, and weight gain of the fed group.…”