Animal performance and welfare of giant freshwater prawn (Macrobrachium rosenbergii) subjected to feed restriction

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.(AU)

Behavior activities of Macrobrachium rosenbergii (De Man, 1879) in monosex and mixed populations, in the laboratory

Monosex all-male populations for the commercial breeding of the freshwater prawn Macrobrachium rosenbergii have been used to lessen the specimens´ aggressiveness and size heterogeneousness. The species´s behavioral variation in mixed, monosex all-male and monosex all-female populations, during the 24-h light-dark period, is assessed. The focal method, with instantaneous report, was employed, featuring a 15-m window for each aquarium, distributed in 12 time shifts throughout the light-dark phase. Eight aquariums contained four prawns each (10 prawns/m2), totaling 96 prawns, monitored for 160 h, during 30 days. Exploring, burrowing, covering with earth, feeding, cleaning, inactivity, crawling, swimming, change and agonistic activity were analyzed. The animals showed a high rate of autogrooming and exploitation during the light and dark phases in three culture modalities, whereas burrowing occurred more frequently during the light period. Agonism was more frequent during the dark phase in all populations, although rates of monosex all-female culture were higher during the light and dark phases when compared to mixed and monosex all-male cultures. The authors recommend shelters and substrates for protection and improvement of the animals´ welfare, especially during the dark shift. Since agonism was more frequent for monosex all-female culture when compared to that in mixed or monosex all-male culture, such population composition is not recommended.(AU)

Behavior activities of Macrobrachium rosenbergii (De Man, 1879) in monosex and mixed populations, in the laboratory

Monosex all-male populations for the commercial breeding of the freshwater prawn Macrobrachium rosenbergii have been used to lessen the specimens´ aggressiveness and size heterogeneousness. The species´s behavioral variation in mixed, monosex all-male and monosex all-female populations, during the 24-h light-dark period, is assessed. The focal method, with instantaneous report, was employed, featuring a 15-m window for each aquarium, distributed in 12 time shifts throughout the light-dark phase. Eight aquariums contained four prawns each (10 prawns/m2), totaling 96 prawns, monitored for 160 h, during 30 days. Exploring, burrowing, covering with earth, feeding, cleaning, inactivity, crawling, swimming, change and agonistic activity were analyzed. The animals showed a high rate of autogrooming and exploitation during the light and dark phases in three culture modalities, whereas burrowing occurred more frequently during the light period. Agonism was more frequent during the dark phase in all populations, although rates of monosex all-female culture were higher during the light and dark phases when compared to mixed and monosex all-male cultures. The authors recommend shelters and substrates for protection and improvement of the animals´ welfare, especially during the dark shift. Since agonism was more frequent for monosex all-female culture when compared to that in mixed or monosex all-male culture, such population composition is not recommended.

Coeficientes de digestibilidade aparente dos nutrientes e da energia de alimentos para Macrobrachium rosenbergii

Na carcinicultura a principal fonte proteica utilizada nas formulações de rações é a farinha de peixe, porém estima-se que nos próximos anos essa fonte proteica não consiga mais atender a demanda dessa atividade, desta forma, a busca por novos ingredientes é de grande importância para minimizar os impactos ambientais gerados, como redução dos estoques pesqueiros e eutrofização dos sistemas aquáticos. O objetivo do presente trabalho foi determinar os coeficientes de digestibilidade aparente da matéria seca, proteína bruta, energia bruta e extrato etéreo dos ingredientes (farinha de peixe, farinha de vísceras de frango, farinha de penas hidrolisadas, farinha de Tenebrio molitor e farinha de Gromphadorhina portentosa) para juvenis de Macrobrachium rosenbergii pelo método indireto de sifonagem. Para determinação dos coeficientes de digestibilidade aparente (CDA) dos ingredientes foram utilizados 90 camarões com peso médio de 15g, distribuídos aleatoriamente entre três caixas de polietileno de 1000L. A ração referência foi formulada de acordo com a exigência do camarão gigante da Malásia com 35% de proteína bruta e 3.600 kcal EB/kg e as rações testes compostas por 70% da ração referência e 30% do ingrediente teste. Os camarões eram alimentos três vezes ao dia (às 07h50, 12h50 e 18h50) até a sua saciedade aparente, sendo fornecido um tempo de 20 minutos para a alimentação; após este intervalo era realizada a limpeza das caixas, onde eram sifonadas as fezes e as sobras de ração. A coleta das fezes foi realizada pelo método indireto de sifonagem, duas vezes ao dia no mesmo local de alimentação (às 07h30 e 18h30), antes do fornecimento do alimento e limpeza das caixas. A temperatura da água foi mantida em 27 °C, oxigênio dissolvido: 6,65 mg/L e o pH: 7,76. Os demais parâmetros como amônia, nitrito, dureza e alcalinidade mantiveram-se dentro dos valores recomendados para a espécie em estudo. Os CDAs da MS, PB e EB foram respectivamente de 73,82; 75,21 e 76,42 para farinha de penas hidrolisadas; 76,48; 81,55 e 85,13 para farinha de vísceras de frango; 61,48; 88,28 e 88,25 para farinha de peixe; 27,49; 68,96 e 75,74 para farinha de Tenebrio molitor e 52,35; 59,48 e 67,64 para a farinha de Gromphadorhina portentosa. Os valores de proteína (%) e energia (kcal/kg) digestíveis foram de 55,20 e 3.711 para farinha de peixe; 47,27 e 4.285 para farinha de vísceras de frango; 34,56 e 4.983 para farinha de Tenebrio molitor; 47,72 e 3.616 para farinha de Gromphadorhina portentosa e 65,03 e 4.145 para farinha de penas hidrolisadas, esses resultados mostram o potencial dessas farinhas como ingredientes em dietas para juvenis do M. rosenbergii.

In prawn farming the main protein source used in the formulations is fish meal, but it is estimated that in the coming years this protein source will no longer be able to meet the demand for this activity, so the search for new ingredients is of great importance to minimize the risks, environmental impacts generated, such as reduction of fish stocks and eutrophication of aquatic systems. The objective of the present study was to determine the apparent digestibility coefficients of dry matter, crude protein, gross energy and ethereal extract of the ingredients (fish meal, poultry visceras meal, hydrolyzed feather meal, Tenebrio molitor meal and Gromphadorhina portentosa meal) for Macrobrachium rosenbergii juveniles by the indirect siphonage method. To determine the apparent digestibility coefficients (ACDs) of the ingredients were used 90 shrimps with average weight of 15g, randomly distributed among three boxes 1000L polyethylene. The reference feed was formulated according to the requirement of the Malaysian giant prawn with 35% crude protein and 3,600 kcal EB/kg and the test diet composed of 70% of the reference diet and 30% of the test ingredient. The prawn were fed three times a day (at 07h50, 12h50 and 18h50) until their apparent satiety, and a time of 20 minutes was provided for feeding; after this interval, the boxes were cleaned, where the faeces and leftover feed were siphoned. The collection of feces was performed by the indirect siphoning method, twice a day at the same feeding site (at 7:30 am and 6:30 pm), before feeding and cleaning the boxes. Water parameters such as temperature were maintained at 27 °C, dissolved oxygen at 6.65 mg /L and pH at 7.76. Other parameters such as ammonia, nitrite, hardness and alkalinity remained within the recommended values for the species under study. The ACDs of DM, CP and GE were respectively 73.82; 75.21 and 76.42 for hydrolysed feather meal; 76.48; 81.55 and 85.13 for poultry visceras meal; 61.48; 88.28 and 88.25 for fish meal; 27.49; 68.96 and 75.74 for Tenebrio molitor meal and 52.35; 59.48 and 67.64 for Gromphadorhina portentosa meal. The values of protein (%) and energy (kcal / kg) digestible in dry matter of 55,20 and 3,711 for fish meal; 47,27 and 4,285 for poultry visceras meal; 34.56 and 4.983 for Tenebrio molitor meal; 47,72 and 3,616 for Gromphadorhina portentosa meal and 65,03 and 4,145 for hydrolysed feather meal, these results show the potential of these flours as ingredients in M. rosenbergii juvenile diets.