Feeding habit of Brown trout (Salmo trutta fario) in upper parts of river Swat, Pakistan / Hábito de alimentação da truta marrom (Salmo trutta fario) nas partes superiores do rio Swat, Paquistão

Salmo trutta fario is the most important fish species of family Salmonidae inhibited in cool waters all over the world including the nortern parts of Pakistan. This study was aimed to find out the prey selection and feeding habits of the species. One hundred and eighty five Salmo trutta fario were captured from March 2016 to April 2017. Feeding intensity as represented by a fullness index (FI), changing with various length groups and season. Out of 185 Brown trout 24 fish stomaches were found empty. The most important and common food items of brown trout were Brachycentridae, Blepharocera, Hydropsychidae, ephemerella spp. Kruskal Wallis H-test were applied on feeding intensity groups consisting of three month group. The test statistic for K.W-H-test were (H=8.13 with df =3) had a p-value of 0.043 < (alpha=0.05 indicates favor of the alternative hypothesis of at least one difference among the feeding intensity groups. The linear relationship of N with index of relative importance and %IRI denoted by least square regression line (N = 35.2 + 22.1%IRI), shows that for 22 prey there is 1% change in IRI. The relationship between total length (mm) and fish body weight (gm) is expressed by Pearson correlation coefficient (r = 0.976), showed that total length (mm) and fish body weight (gm.) is highly correlated. Descriptive statistics are used for the stomach fullness, which shows that feeding intensity was recorded higher from March to May. A total of 2289 preys was recorded including the most common were; Trichoptera, Hydropsychidae, Brachycentridae, diptera, blepharocera, ephemerala, chironomida, honey bees, grass hopper, locust, trout egg, trochanter, plant tissue, stones were retrieved from the gut contents of brown trout. According to index of relative importance IRI% four preys represents major components of the diet. The highest IRI% was recorded in Brachycentridae (39.38%), followed by blepharocera (13.23%), [...].

Salmo trutta fario é a espécie de peixe mais importante da família dos salmonídeos, inibida em águas frias em todo o mundo, incluindo as partes do noroeste do Paquistão. Este estudo teve como objetivo conhecer a seleção de presas e os hábitos alimentares da espécie. Cento e oitenta e cinco Salmo trutta fario foram capturados de março de 2016 a abril de 2017. Intensidade de alimentação representada por um índice de plenitude (FI), mudando com vários grupos de comprimento e estação. De 185 trutas, 24 estômagos de peixes foram encontrados vazios. Os itens alimentares mais importantes e comuns da truta marrom foram brachycentridae, blepharocera, hydropsychidae, ephemerellaspp. O teste H de Kruskal Wallis foi aplicado em grupos de intensidade de alimentação consistindo de um grupo de três meses. A estatística de teste para o teste KW-H foi (H = 8,13 com df = 3) teve um valor de p de 0,043 <(alfa = 0,05 indica favor da hipótese alternativa de pelo menos uma diferença entre os grupos de intensidade de alimentação. relação de N com o índice de importância relativa e% IRI denotado pela linha de regressão do mínimo quadrado (N = 35,2 + 22,1% IRI), mostra que para 22 presas há 1% de mudança no IRI. A relação entre comprimento total (mm) e peixes o peso corporal (gm) é expresso pelo coeficiente de correlação de Pearson (r = 0,976), mostrou que o comprimento total (mm) e o peso corporal dos peixes (gm.) são altamente correlacionados. Estatísticas descritivas são usadas para a plenitude do estômago, o que mostra que a intensidade da alimentação foi registrado mais alto de março a maio. Um total de 2.289 presas foi registrado, incluindo os mais comuns foram; trichoptera, hydropsychidae, brachycentridae, diptera, blepharocera, efemérala, chironomida, abelhas, funil de grama, gafanhoto, ovo de truta, trocânter, tecido vegetal, pedras foram retiradas do intestino conteúdo de truta marrom. De acordo com o índice de importância relativa [...].

[ effect of yeast supplementation on the growth and immune system in rainbow trout [Oncorhynchus mykiss]]

Today, uses of natural substances are preferred to chemical and synthetic compounds for growth and immune enhancement of aquatic organisms. The aim of this research was to evaluate the effect of Saccharomyces cerevisiae extract and hydrolyzed powder on growth parameters and resistance of rainbow trout against temperature and hypoxia stresses with a bacterial challenge. For this purpose six hundred rainbow trout [50 +/- 5 g mean weight] were purchased from a local fish farm and transferred to the laboratory. After acclimatization to the laboratory conditions the fish were randomly divided into four groups each with triplicate. The first group was fed with a commercial diet [control] while the other groups received yeast extract, hydrolyzed powder and a mixture of them with the commercial diet. Fish were cultured in a 300 l polyethylene tank for 60 days and growth parameters were analyzed at days 0 and 60. Also, at the end of study the fish were challenged with hypoxia and temperature stresses with an experimental bacterial infection. Results showed that the extract and hydrolyzed powder of Saccharomyces cerevisiae in combination significantly [p=0.021] improved rainbow trout growth parameters compared with the control. The results also proved that fish survival significantly increased following feeding with a mixture of the extract and hydrolyzed powder after thermal [69.55 +/- 4.59], hypoxia [96.55 +/- 5.34] and yersiniosis [49.11 +/- 2.18] challenge than the control. Dietary administration of yeast extract with mixture of hydrolyzed powder of Saccharomyces cerevisiae could improve rainbow trout growth parameters and increase the resistance against stresses and disease