Many studies have been made about the physio‐logical effects of isolated chronic or acute stress. However, few studies have been made to assess the combination of both responses. The fish submitted to chronic stress may be subjected to an additional acute stressor. The aim of the present work was to evaluate the acute stress response in Nile tilapia Oreochromis niloticus (L.) previously subjected to chronic stress. For this, two experiments were performed. In the first experiment, the fish were subjected to chronic stress followed by an additional acute stress. In the second experiment, the fish were submitted only to an acute stress. The data showed that Nile tilapia fingerlings can adapt to chronic stress situations, and this decreases, but does not eliminate, their capacity to respond to an additional acute stressor. In both experiments, plasma cortisol levels reached a peak 1 h after administration of the acute stressor. In fish previously submitted to chronic stress, the highest concentration of plasma cortisol measured was 196 ng mL–1. This value was significantly different from the cortisol concentration obtained in the second experiment (267 ng mL–1) with non‐chronically stressed fish. The data also suggest that the chronic stress response can provoke a reduction in performance and growth rates compared with non‐stressed fish.
Several researchers have demonstrated that the stocking density and social interactions between conspeci®c ®sh have signi®cant in¯uence on stress response. Nile tilapia Oreochromis niloticus (L.) is a teleost ®sh with hierarchical organization. Nile tilapia ®ngerlings (20 6 5 g) were distributed in 30 tanks, 12 tanks with single ®sh and six with paired, groups of ®ve and 10 ®sh, respectively, and held in these 100-L plastic tanks for 60 days. Six tanks of single ®sh and three of other groups received an acute stressor on the 61st day. The control ®sh reared singly and in pairs showed a plasma cortisol concentration similar to that normally found as a resting cortisol concentration in other ®sh. One surprising result was the absence of the formation of a hierarchical dominant/submissive relation between the ®sh held in pairs. One possible explanation for this result is the volume of the tank, so that each ®sh exerted a territorial position in a corner of the tank, and the ®ghting and antagonistic encounters did not occur. In the ®veand 10-®sh groups, the resting plasma cortisol concentrations were higher, which may indicate a chronic stress response during the 60 days of the experiment, attributable to social stress. The application of an acute stressor signi®cantly increased the plasma cortisol levels in all stocking densities, with values reaching 135±298 ng mL ±1 . When comparing the stressed ®sh, the 10-®sh groups showed a more intense stress response in relation to the other groups.
RESUMO -Verificou-se o efeito dos genótipos halotano homozigoto dominante e heterozigoto e dos sistemas de criação confinado sobre piso de cimento, confinado sobre cama de maravalha e ao ar livre sobre a qualidade da carne suína. Foram utilizados 96 suínos machos castrados selecionados através do exame de DNA genômico, utilizando-se a técnica de reação em cadeia de polimerase (PCR) para amplificar a região do receptor rianodina. A região amplificada foi clivada pela técnica polimorfismo do comprimento dos fragmentos de restrição (RFLP). Mediu-se o pH nos músculos Longissimus dorsi e Semimembranosus aos quarenta e cinco minutos e vinte e quatro horas após o abate. A capacidade de retenção de água foi avaliada em amostras do músculo Longissimus dorsi através das técnicas de perda de líquido por gotejamento, de cocção e de descongelamento. Escores para a cor e o grau de marmorização da carne foram atribuídos com auxílio de padrões fotográficos. A maciez da carne foi medida pela força de cisalhamento em equipamento Warner-Bratzler Shear. Suínos com gene halotano heterozigotos apresentaram valores inferiores de pH, menor capacidade de retenção de água e uma freqüência de carcaças com carne PSE três vezes maior. O sistema de criação não afetou os valores de pH inicial e final ou a capacidade de retenção de água da carne suína. A maior incidência de carne PSE foi observada nas carcaças dos suínos criados em sistema confinado sobre piso de concreto. Não houve efeito significativo da interação genótipo halotano e sistema de criação para as características avaliadas.Palavras-chave: criação ao ar livre, criação sobre cama de maravalha, gene halotano, PSE Effect of the Halothane Genes and Rearing Systems on Meat Quality of PorkABSTRACT -The effect of halothane genotypes (heterozygous and dominant homozygous) and intensive rearing systems (indoor, wood shavings bedding and outdoor) on pork quality were determinated. Ninety six castrated male pigs were used for the trial. Identification of the halothane genotype was determined in blood samples using the DNA-test, based on the polymerase chain reaction (PCR) amplification of the critical region of the ryanodine receptor and subsequent restricion of the amplifield fragment by the restriction fragment lengh polymorfism (RFLP) technique. The pH at 45 minutes and 24 hours after slaughter was measured on the Longissimus dorsi and Semimembranosus muscles. At the laboratory, the Longissimus dorsi muscle was used for the evaluation of the color, marbling, drip loss, defrosting loss and cooking loss and shear force. The muscle of heterozygous pigs for the halothane gene had lower pH and higher drip loss and the incidence of the PSE condition in this genotype was three times higher. The rearing system did not affect the initial and ultimate pH or water holding capacity. Indoor reared pigs had greater frequency of PSE carcass. The interaction between halothane genotypes and rearing systems had no significant effect on any trait studied.
RESUMO O objetivo deste trabalho foi o de avaliar o efeito do
RESUMO Zootec., v.31, n.2, p.954-961, 2002 (suplemento)
RESUMO -Este trabalho foi conduzido com o objetivo de comparar a eficiência de diferentes níveis de fitase em relação à suplementação de fosfato inorgânico (fosfato bicálcico), quando adicionados em dietas sem e com farelo de arroz desengordurado (FAD). Foram utilizados 128 suínos com peso inicial médio de 21,2 ± 2,4 kg, alojados em baias coletivas, para avaliar o desempenho nas fases de crescimento e terminação. Os suínos foram abatidos com peso médio de 95,4 ± 5,3 kg e coletado o osso metacarpo para determinação do cálcio e do fósforo. Foram usados oito tratamentos, sendo quatro dietas sem FAD (milho e farelo de soja) e quatro dietas com 30% de inclusão de FAD, nas quais foram adicionados níveis de 0, 750 ou 1000 UF (Unidades de Fitase)/kg. Foi observado que adicionar fitase, tanto em dietas sem FAD quanto em dietas com FAD, melhora a disponibilidade do fósforo orgânico. Com os níveis de 750 e 1000 UF/kg adicionados em ambas as dietas, sem suplementação de fosfato bicálcico, não houve prejuízo sobre o desempenho dos animais. Entretanto, as características ósseas são prejudicadas se as dietas com fitase não forem suplementadas com a fonte de fósforo inorgânico.Palavras-chave: cálcio, disponibilidade, enzima, fitato, fósforo Use of Phytase in Diets with or without Defatted Rice Bran for Growing/Finishing PigsABSTRACT -The objective of this work was to compare the efficiency of different levels of phytase with the use of inorganic phosphate (dicalcium phosphate) when added to diets with or without defatted rice bran (DRB). One hundred and twenty eight pigs with average initial weight of 21.6 ± 2.4 kg were housed in collective boxes for the pig performance evaluation in the growing and finishing phase. The pigs were slaughtered with an average weight of 95.42 ± 5.3 kg and the metacarpus bones were collected to determine the calcium and phosphorus content. Eight treatments were used with four diets being formulated without DRB (cornsoybean meal) and the other four diets with DRB. The phytase levels added in the diets were 0, 750 or 1000 PU/kg of the diet. It was observed that adding phytase in diets without and with DRB improved the availability of the organic phosphorus. The addition of phytase at levels of 750 or 1000 PU/kg, with or without DRB in the diet, allows the withdraw of the inorganic phosphorus source from diet if considering pig performance. However, the bone characteristics are affected when the diets with phytase were not supplemented with a source of inorganic phosphorus. . Zootec., v.31, n.5, p.2002-2010, 2002 Introdução A maior parte das dietas para suínos e aves são compostas por milho e farelo de soja, porém um alimento que pode substituir parcialmente o milho é o farelo de arroz desengordurado (FAD).É um ingrediente resultante da extração por solvente da gordura do farelo de arroz integral para a produção de óleo comestível (Oliveira & Molina, 1981). Possui alto teor de proteína bruta, extrativo não-nitrogenado e alta quantidade de fósforo total, cerca de 2,13% (Embrapa, 1985), apesar deste úl...
RESUMO -O objetivo deste trabalho foi comparar a eficiência da fitase em relação à do fosfato inorgânico (fosfato bicálcico), quando adicionado em dietas sem e com farelo de arroz desengordurado (FAD). Foram utilizados 128 suínos (50% machos castrados e 50% fêmeas) alojados em baias coletivas para se avaliar o desempenho e determinar na fase de crescimento a digestibilidade do cálcio e do fósforo, por intermédio do método do indicador (óxido crômico), e a concentração de cálcio e fósforo na vértebra coccígea dos animais. Foram usados oito tratamentos, sendo quatro dietas sem FAD (milho e farelo de soja) e quatro dietas com 30% de FAD. Foram adicionados níveis de 0, 750 e 1000 UF (Unidades de Fitase)/kg em ambas as dietas com e sem FAD, sendo que a terceira dieta sem FAD apresentou 750 UF/kg sem fosfato inorgânico, enquanto nas dietas com FAD uma delas não foi suplementada nem com fitase, nem com fosfato bicálcico. Dietas com e sem FAD suplementadas com fitase tiveram a mesma eficiência que as suplementadas com fosfato bicálcico sobre o desempenho dos animais. Entretanto, a fitase ocasionou redução na excreção de cálcio e fósforo, nas fezes e na composição óssea dos animais, somente quando foi suplementada em dietas sem FAD.Palavras-chave: cálcio, farelo de arroz desengordurado, fitase, fósforo, suínos Effect of Phytase in Diets with or without Inorganic Phosphate to Growing PigsABSTRACT -The objective of this trial was to compare the efficiency of phytase with an inorganic phosphate (dicalcium phosphate) when added to diets with or without defatted rice bran (DRB). One hundred and twenty eight pigs (50% barrows and 50% gilts) were housed in collective cages to evaluate the animals performance in the growing phase, and to determine the digestibility of the calcium and phosphorus using chromium oxide as an indicator and the concentration of calcium and phosphorus in the coccyces vertebra of the animals. Eight treatments were used: four diets without DRB (corn-soybean meal) and four diets with 30% of DRB. Phytase levels of 0, 750 and 1000 PU/kg were added to both diets with or without DRB, and the third one without DRB presented 750 PU/kg without inorganic phosphate, while in the diets with DRB one of them was not supplemented neither with phytase and nor with inorganic phosphate. Diets with or without DRB supplementation showed the same efficiency on the performance of the animals as that ones supplemented with dicalcium phosphate. However, phytase reduced the excretion of calcium and phosphorus in the feces and in the bone composition of the animals, only when was supplemented in diets without DRB.
RESUMO -O objetivo deste trabalho foi verificar o efeito dos genótipos halotano homozigoto dominante e heterozigoto e de três sistemas de criação (confinado sobre piso de cimento, confinado sobre cama de maravalha e ao ar livre) no desempenho produtivo e na qualidade da carcaça e da carne suína. Foram utilizados 96 suínos machos castrados selecionados pelo exame de DNA genômico no sangue utilizando-se a técnica de reação em cadeia da polimerase (PCR) para amplificar a região do receptor rianodina. A região amplificada foi clivada pela técnica do polimorfismo do comprimento dos fragmentos de restrição (RFLP). Nas fases de crescimento e terminação, avaliaram-se ganho de peso, consumo de ração e conversão alimentar. Após o abate, as carcaças foram pesadas e tipificadas eletronicamente. Vinte e quatro horas após o abate, foram separados e pesados o pernil e o carrê e medida a área de olho de lombo. A presença do gene halotano não afetou o desempenho dos suínos, mas aumentou a porcentagem de carne magra e diminuiu a quantidade de gordura na carcaça. Suínos criados no sistema intensivo ao ar livre apresentaram menor ganho de peso e pior conversão alimentar. No sistema intensivo de criação confinado sobre cama, os suínos produziram carcaças com menor quantidade de carne magra e maior quantidade de gordura. Não houve efeito significativo da interação genótipo halotano e sistema de criação para as características avaliadas.Palavras-chave: criação ao ar livre, criação sobre cama de maravalha, carne suína, gene halotano Effect of the Halothane Genes and Rearing Systems on Growth Performance and PigCarcass Quality ABSTRACT -The objective of this study was to evaluate the effect of the halothane genotypes (heterozygous and dominant homozygous) and intensive rearing systems (indoor, wood shavings bedding and outdoor) on growth performance, carcass and meat yield. Ninety six castrated male pigs were used for the trial. Identification of the halothane genotype was determined in blood samples using the DNA-test, based on the polymerase chain reaction (PCR) for amplification of the critical region of the ryanodine receptor and subsequent restriction of the amplified fragment by restriction fragment lengh polymorfism technique (RFLP). Growth and finishing performance were evaluated by weight gain, feed intake and feed efficiency. Carcass quality was evaluated by backfat and muscle depth, meat percentage through Hennessy Grading Probe and carcass weight. Twenty four hours after slaugther, ham and loin weight were recorded and the loin eye area was evaluated. The growth performance was similar for the two genotypes. The heterozygous pigs for the halothane gene had higher percentage of fat-free lean and less fat in the carcass. Outdoor reared pigs showed lower average daily gain and worst efficiency than pigs reared indoor. Carcasses of pigs reared under wood shavings bed had less fat-free lean and greater backfat thickeness. The interaction between halothane genotypes and rearing systems had no significant effect on any trait studie...
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