ABSTRACT Behavior activities of giant freshwater prawn Macrobrachium rosenbergii juvenile, their performance, and acquired lesions when under temporary feed restrictions were analyzed. Five animals/experimental units (10 prawns/m2) were employed for treatments DFL – daily feed supply in the light phase; DFD – daily feed supply in the dark phase; AFL – alternating feed supply in the light phase; and AFD – alternating feed supply in the dark phase, for a 24-hour period, with four replications each. Prawns were fed a pellet diet, twice a day, with 10% of their biomass/day. Specimens were monitored during 60 consecutive days, with behavior recording daily and weighed every 10 days, with assessment of lesions and/or amputated limbs at the end of the experimental period. Types of behavior comprised exploring, grooming, inactivity, crawling, swimming, excavation, burrowing, agonism, and feed ingestion by scan sampling, with instantaneous registration every 60 s, in 15-min windows, before and after feed, in light and dark phases. Feed restricted in alternate days during light and dark phases did not interfere in growth or survival of the specimens, with increase in apparent feed intake and less feed conversion ratio and specific growth rate. Agonistic behavior was higher in specimens with feed restrictions, with an increase in the number of lesions and amputations. The above demonstrates welfare decrease in farmed M. rosenbergii and depreciation in the quality of the final product.

O objetivo deste trabalho foi avaliar o efeito do tipo de substrato sobre a preferência, o enterramento e a atividade natatória de camarões (Litopenaeus vannamei). Juvenis (0,93±0,29 g) e adultos machos e fêmeas (10,05±1,18 g) foram observados durante 24 horas, por meio do método animal focal, com registros instantâneos. Foram testadas as seguintes granulometrias (tratamentos) dos substratos: I, 100% C; II, 50% C + 50% B; III, 50% A + 50% C; IV, 100% B; V, 50% B + 50% A; e VI, 100% A, em que as letras referemse ao diâmetro médio das partículas, A = 0,25-2,0 mm; B = 0,0625-0,25 mm; e C = <0,0625 mm. Foram aplicados seis tratamentos com 18 repetições para cada categoria: camarões juvenis, machos e fêmeas. Cada indivíduo foi exposto por 24 horas aos seis tipos de substrato, simultaneamente, e o seu comportamento foi observado nas fases clara e escura do dia. A natação ocorreu principalmente na fase escura e o enterramento, na fase clara, no substrato IV. Os camarões juvenis e adultos (machos ou fêmeas) preferem o substrato composto de areia fina e muito fina (0,0625-0,25 mm), tanto para permanência quanto para enterramento.

The objective of this work was to evaluate the effect of substrate type on the preference, burial, and natatory activity of shrimp (Litopenaeus vannamei). Juvenile (0.93±0.29 g) and adult males and females (10.05±1.18 g) were observed during 24 hours using the focal animal method, with instantaneous recording. The following soil granulometries (treatments) were tested: I, 100% C; II, 50% C + 50% B; III, 50% A + 50% C; IV, 100% B; V, 50% B + 50% A; and VI, 100% A, in which the letters reffer to particle mean diameter, A = 0.25-2.0 mm, B = 0.0625-0.25 mm, and C = <0.0625 mm. Six treatments were applied with 18 replicates for each category: juvenile, male, and female shrimp. Each individual was simultaneously exposed for 24 hours to the six types of substrates, and its behavior was observed in the light and dark phases of the day. Swimming occurred mainly during the dark phase, and burial in the light phase in substrate IV. The juvenile and adult shrimp (male or female) prefer substrate composed of fine and very fine sand (0.0625-0.25 mm), both for residence and for burial.