Galileu Crovatto Veras

Fotoperíodo sobre parâmetros fisiológicos relacionados ao estresse em alevinos de tilápia-do-nilo

The objective of this study was to evaluate the influence of different photoperiods on physiological parameters related to stress in Nile tilapia fingerlings (Oreochromis niloticus). A completely randomized design with five treatments (0L, 6L, 12L, 18L, 24L) and four replications was used, and the aquarium as the experimental unit. One hundred and sixty tilapia fingerlings, 3.21±0.05g and 4.35±0.07cm were distributed in 20 aquariums of 20L in a recirculation system with temperature controlled at 27 ° C and density of eight fish per aquarium. Feeding was performed twice daily with extruded feed containing 40% crude protein, for a period of 75 days. At the end of experimental period, the data of survival, cortisol, glucose and hematocrit were subjected to analysis of variance and, subsequently, in case of significance (P 0.05).

Identification of insulin-like growth factor-I in boar seminal plasma and its influence on sperm quality

The present research was carried out to investigate the relationships between sperma- tozoal parameters and concentrations of IGF-I in the seminal plasma of boar. Semen samples (duplicates) were collected from mature boars (n=27). In each ejaculate, the macroscopic and microscopic characteristics were determined. After centrifugation to separate sperm cells from seminal plasma, concentrations of IGF-I in seminal plasma samples were determined by a human- specific immunoassay kit. The mean concentration of the boar seminal plasma (n=54 samples) IGF-I was 1.5±0.2 ng/mL. There was no correlation (p>0.05) between IGF-I with most of the evaluated parameters. There was only a low negative correlation (-0.29; p=0.0331) between the concentration of IGF-I in seminal plasma and the motility degradation rate. This study suggests that IGF-I in the seminal plasma of boars is not related to initial fresh semen parameters. However, the hormone did increase the duration of sperm motility.

Desempenho, composição corporal e respostas fisiológicas de tambaqui alimentados com dietas com extrato de chá-verde

The objective of this work was to evaluate the performance, body composition, and physiological state of tambaqui (Colossoma macropomum) fingerlings fed diets containing different levels of green tea (Camellia sinensis) extract (GTE). A completely randomized design was used with five treatments, different levels of GTE (0.00, 0.05, 0.30, 0.55, and 0.80 g kg-1) and three replicates. The diets were offered to fingerlings twice a day, for 90 days. The increase of dietary GTE levels promoted a positive quadratic effect on body lipids, hepatic lipids, retention of body lipids, glucose, and total triglycerides, and the minimum values of these variables were estimated with 0.61, 0.54, 0.73, 0.60, and 0.30g kg-1 GTE in the diet, respectively. There was a negative quadratic effect of the extract on body protein and hemoglobin with the increased GTE dietary level, and the maximum values of these variables were estimated with 0.59 and 0.46 g kg-1 GTE dietary level, respectively. Total cholesterol levels showed a linear reduction with increased GTE dietary level. The inclusion of GTE in the diet, although not affecting performance, decreases body and hepatic fat; reduces the levels of total cholesterol, triglycerides, and glucose; and promotes the increase of body protein of tambaqui fingerlings, improving fish health conditions, during cultivation, and the quality of the final product.

Canibalismo, desempenho de crescimento e composição corporal de juvenis de trairão em diferentes fotoperíodos

The objective of this work was to determine the effect of photoperiod on the cannibalism, growth, and body composition of giant trahira (Hoplias intermedius) juveniles. A completely randomized design was employed, with four photoperiods – 0L:24D, 6L:18D, 12L:12D, and 18L:6D, hours of light (L): dark (D) – and four replicates, for a period of 90 days. The analyzed parameters were: cannibalism, growth in weight and length, food consumption, feed conversion, protein efficiency rate, muscle growth, and body composition (moisture, lipid, ash, and crude protein). Fish from the 12L:12D photoperiod showed the highest survival rate and no cannibalism, as well as a great uniformity for length and mass values at the end of the experiment. The best photoperiod for giant trahira juveniles is 12L:12D, as these fish showed growth uniformity and no cannibalism, while fish from the 6L:18D and 18L:6D groups had a greater diameter of white muscle fibers and a higher frequency of greater diameter fibers. Giant trahira showed the lowest value for lipids at 6L:18D and the highest value at 12L:12D. Photoperiod affects survival and cannibalism; regarding body composition, only lipids are influenced by photoperiod.

Influence of photoperiod on growth, uniformity, and survival of larvae of the Amazonian ornamental Heros severus (Heckel, 1840)

The objective of this work was to evaluate the influence of photoperiod on growth, uniformity, and survival of larvae of the Amazonian ornamental fish severum (Heros severus). A completely randomized study was used with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replicates, with the aquaria as the experimental unit. Two hundred severum larvae (3.20±0.16 mg and 5.60±0.00 mm) were distributed into 20 aquariums of one litre at a density of 10 larvae per litre. For a period of 15 days, feed was supplied four times daily with Artemia nauplii in a proportion of 160 nauplii/larvae/feeding. At the end of the experimental period, growth, uniformity, and survival data were subjected to analyses of variance and significance. Manipulation of the photoperiod showed no change in variables because there was no difference in the growth, uniformity, or survival of severum larvae. Thus, for larvae of this species of up to 20 days of age, the manipulation of the photoperiod is not advantageous due to the possible increase in production costs. Therefore, it is recommended to use the photoperiod close to the natural environment.

Fotoperíodo e frequência alimentar na larvicultura do peixe beta

Com este trabalho, objetivou-se avaliar o crescimento, a uniformidade e a sobrevivencia das larvas de Betta splendens, submetidas a diferentes fotoperiodos e frequencias de alimentacao. Foram distribuidos aleatoreamente 480 individuos (4,53mg ± 0,32 e 5,51 ± 0,58mm) em 48 recipientes plasticos (1L), com densidade de 10 larvas/ L. Foi utilizado um delineamento experimental inteiramente ao acaso, com quatro repeticoes, em arranjo fatorial 6x2, com seis fotoperiodos (0L:24E, 6L:18E, 12L:12E, 16L:8E, 20L:4E, 24L:0E) e duas frequencias de alimentacao (duas ou quatro vezes/ dia). Durante um periodo de 15 dias, as larvas foram alimentadas com nauplios de Artemia, na proporcao de 800 nauplios/ larva/ dia. Larvas de beta submetidas aos fotoperiodos de 12L:12E e 16L:8E apresentaram o maior crescimento em peso (P<0,10), enquanto as que foram alimentadas quatro vezes ao dia apresentaram maior crescimento em comprimento e uniformidade (P<0,10). No entanto, os individuos que foram alimentados quatro vezes ao dia apresentaram menor sobrevivencia quando submetidos aos fotoperiodos de 16L:8E, 20L:4E e 24L:0E (P<0,10). Por outro lado, as larvas submetidas aos fotoperiodos de 12L:12E, 16L:8E e 20L:4E apresentaram maior taxa de sobrevivencia quando alimentadas duas vezes ao dia (P<0,10). Portanto, ao se preconizar maior crescimento, uniformidade e sobrevivencia das larvas de Betta splendens, recomenda-se a realizacao da larvicultura dessa especie sob o fotoperiodo de 12L:12E, com o fornecimento de nauplios de Artemia em duas alimentacoes diarias.