Zootechnical performance, degree of steatosis and the genotoxic potential in yellowtail tetra Astyanax lacustris fed with different levels of L-carnitine / Desempenho zootécnico, grau de esteatose e potencial genotóxico de lambaris Astyanax lacustris alimentados com diferentes níveis de L-carnitina

L-carnitine perform a major role in transporting long-chain fatty acids into the mitochondria, where they are oxidized. It has been used in animal diets to decrease fat and increase muscle protein. The aim of this study was to evaluate the zootechnical performance, degree of steatosis in the liver, and genotoxic potential in Astyanax lacustris fed with different levels of L-carnitine (LC). Yellowtail tetra juveniles (n = 140) were distributed in 20 tanks of 70 L, with seven fish in each, in a water recirculation system with controlled temperature (27±0.1°C). The treatments with different levels of L-carnitine supplementation were: 0 (control), 250, 500, 750, and 1000 mg of LC per kg of food. The diets were provided twice a day for 60 days. The results showed that the different levels of LC did not affect (P>0.05) weight gain, survival, viscerosomatic index, and the liver hepatocytes showed a normal appearance. However, the use of LC supplementation showed genotoxic potential with a significant difference (P<0.05) for cell alterations when compared to the control at concentrations above 500mg kg-1.

A L-carnitina exerce um papel importante no transporte de ácidos graxos de cadeia longa até a mitocôndria para serem oxidados e tem sido incorporada em rações para animais com o objetivo de diminuir a deposição de gordura e aumentar a proteína muscular. O objetivo deste trabalho foi avaliar o desempenho zootécnico, o grau de esteatose no fígado e o potencial genotóxico em Astyanax lacustris alimentados com diferentes níveis de L-carnitina (LC). Juvenis de lambari-do-rabo-amarelo (n=140) foram distribuídos em 20 caixas de 70L, sete peixes em cada, em um sistema de recirculação de água com temperatura controlada (27±0,1°C). Os tratamentos com os níveis de suplementação foram: 0 (controle), 250, 500, 750 e 1000 mg de LC kg-1 de ração. As dietas foram fornecidas duas vezes ao dia, durante 60 dias. Os resultados mostraram que os diferentes níveis de LC não influenciaram (P>0,05) o ganho de peso; a sobrevivência, o índice viscerossomático e os hepatócitos do fígado apresentaram-se com aparência normal. No entanto, a suplementação com LC apresentou potencial genotóxico com diferença significativa (P<0,05) para alterações celulares quando comparada ao controle em concentrações superiores a 500mg kg-1.

Valor nutricional do capim-elefante verde colhido em diferentes idades de rebrota / [Nutritional value of fresh elephantgrass harvested at different regrowth ages]

Avaliou-se o valor nutricional do capim-elefante verde colhido aos 56, 84 e 112 dias de idade, por meio do consumo e da digestibilidade em ovinos, da degradabilidade in situ e da cinética da fermentação ruminal. O capim-elefante colhido aos 56 dias proporcionou maiores valores de consumo da MS (1204,81g/dia), da EB (4910,41kcal/dia), da ED (3436,21kcal/dia) e da PB (130,90g/dia). Para o capim-elefante colhido aos 56 dias, ainda foram observados os maiores valores de digestibilidade da MS (70,64%), da EB (70,11%), da PB (68,96%), da FDN (71,4%) e do conteúdo ED (2,86Mcal/kg MS). Com o avanço da idade de corte, houve redução da degradabilidade potencial da MS (77,99% x 68,33%), da PB (84,80% x 56,52%) e da FDN (72,18% x 64,33%), para as idades de corte de 56 e 112 dias, respectivamente. O capim cortado aos 56 dias apresentou maior valor de produção cumulativa de gases (210,50mL/g de MS) e de degradabilidade da matéria seca (63,9%) após 96 horas de fermentação. O capim-elefante verde deve ser colhido aos 56 dias de rebrota em razão das características nutricionais apresentadas.(AU)

The nutritional value of fresh elephant grass harvested at 56, 84 and 112 days of age was evaluated by intake and digestibility in sheep, in situ degradability, and ruminal fermentation's kinetics. The elephant grass harvested at 56 days provided higher DM intake (1204.81g/day), GE (4910.41kcal/day), DE (3436.21kcal/day), and CP (130.90g/day) values. Furthermore, the highest DM (70.64%), GE (70.11%), DE (2.86%) and CP (68.96%) digestibility values were observed at 56 days. With the increase in the harvest age there was a reduction in the DM (77.99 x 68.33%), CP (84.80 x 56.52%) and NDF (72.18 x 64.33%) potential degradability in the treatments 56 and 112 days, respectively. Higher values of cumulative gas production (210,50mL/g DM) and DM degradability for elephant grass were observed at 56 days, after 96 hours of fermentation. The fresh elephant grass should be harvested at 56 days of regrowth due to the nutritional characteristics found in this study.(AU)

O estresse por calor diminui a fertilidade de fêmeas bovinas por afetar o esenvolvimento oocitário e o embrionário / Heat stress disrupts fertility of bovine females affecting the oocyte and embryo development

Para tentar minimizar as perdas provocadas pelo estresse por calor, os bovinos, principalmente oszebuínos que foram selecionados em clima tropical, conseguiram desenvolver mecanismos de tolerância aocalor. Entretanto, o desempenho reprodutivo de bovinos, principalmente de taurinos, é severamente afetado pelocalor dos meses quentes do ano. Desta forma, considerando que a diminuição da fertilidade devido ao estressepor calor constitui um problema multifatorial, esta revisão tem por objetivo compreender como e quando oestresse por calor afeta o desenvolvimento oocitário e o embrionário, a fim de desenvolver estratégias potenciaisque aumentem a fertilidade de rebanhos bovinos sob estresse por calor.(AU)

Bovines developed in tropical areas acquired genes that determine thermotolerance allowing theseanimals to reach success in reproductive performance. However, fertility, mainly in Bos taurus, is severelyaffected by heat stress in the hot months of the year. Thus, considering that the deleterious effect of heat stress isa multifactorial problem, this review aims to present the relevant and recent information to obtain a betterunderstanding of how and when heat stress affects the embryonic development, offering a basis for thedevelopment of potential strategies to increase fertility in a hot environment.(AU)

O estresse por calor diminui a fertilidade de fêmeas bovinas por afetar o esenvolvimento oocitário e o embrionário / Heat stress disrupts fertility of bovine females affecting the oocyte and embryo development

Para tentar minimizar as perdas provocadas pelo estresse por calor, os bovinos, principalmente oszebuínos que foram selecionados em clima tropical, conseguiram desenvolver mecanismos de tolerância aocalor. Entretanto, o desempenho reprodutivo de bovinos, principalmente de taurinos, é severamente afetado pelocalor dos meses quentes do ano. Desta forma, considerando que a diminuição da fertilidade devido ao estressepor calor constitui um problema multifatorial, esta revisão tem por objetivo compreender como e quando oestresse por calor afeta o desenvolvimento oocitário e o embrionário, a fim de desenvolver estratégias potenciaisque aumentem a fertilidade de rebanhos bovinos sob estresse por calor.

Bovines developed in tropical areas acquired genes that determine thermotolerance allowing theseanimals to reach success in reproductive performance. However, fertility, mainly in Bos taurus, is severelyaffected by heat stress in the hot months of the year. Thus, considering that the deleterious effect of heat stress isa multifactorial problem, this review aims to present the relevant and recent information to obtain a betterunderstanding of how and when heat stress affects the embryonic development, offering a basis for thedevelopment of potential strategies to increase fertility in a hot environment.

Hypoosmotic swelling test in young Nelore bulls classified as sound and unsound for breeding

This work aimed to study the correlations between the physical characteristics of semen, sperm morphology and the biochemical integrity of the plasmatic membrane of raw sperm in young Nelore bulls (Bos taurus indicus). A total of 420 bulls between 18 and 22 months of age were examined for breeding soundness according to the criteria established by the Brazilian College of Animal Reproduction. After physical and morphological evaluation, semen was tested with a hypoosmotic test. To accomplish this, 10 µl of fresh semen was incubated in 1 ml of hypoosmotic solution (150 mOsm/kg) for 60 min at 37°C. After the breeding soundness evaluation, 83% (350/420) of the bulls were classified as sound for breeding. There were no significant differences between the mean testicular biometry, scrotal circumference and the percentage of spermatozoa reactive to the hypoosmotic test (43.9 ± 21.1% vs. 43.6 ± 19.3%) in bulls classified as sound and unsound for breeding (P > 0.05), although there were significant differences between the averages for all physical and morphological aspects of the sperm between the two groups (P 0.05). In this study, the hypoosmotic test was not an efficient predictor of the reproductive potential of young Nelore bulls.

Hypoosmotic swelling test in young Nelore bulls classified as sound and unsound for breeding

This work aimed to study the correlations between the physical characteristics of semen, sperm morphology and the biochemical integrity of the plasmatic membrane of raw sperm in young Nelore bulls (Bos taurus indicus). A total of 420 bulls between 18 and 22 months of age were examined for breeding soundness according to the criteria established by the Brazilian College of Animal Reproduction. After physical and morphological evaluation, semen was tested with a hypoosmotic test. To accomplish this, 10 µl of fresh semen was incubated in 1 ml of hypoosmotic solution (150 mOsm/kg) for 60 min at 37°C. After the breeding soundness evaluation, 83% (350/420) of the bulls were classified as sound for breeding. There were no significant differences between the mean testicular biometry, scrotal circumference and the percentage of spermatozoa reactive to the hypoosmotic test (43.9 ± 21.1% vs. 43.6 ± 19.3%) in bulls classified as sound and unsound for breeding (P > 0.05), although there were significant differences between the averages for all physical and morphological aspects of the sperm between the two groups (P < 0.05). The hypoosmotic test did not correlate with the main characteristics of semen quality (P > 0.05). In this study, the hypoosmotic test was not an efficient predictor of the reproductive potential of young Nelore bulls.(AU)