Oral supplementation with vitamin E and fertility in young bulls raised in Brazilian midlewest
The sperm cells are highly susceptible to peroxidative damage, such damage in their sperm membrane occurs due to oxidative stress that is responsible for the reduction in the fertility of sperm. One of the causes of the increase in oxidative stress is increased environmental heat stress and consequent increase in temperature testicular promoting the increase in NADPH oxidase activity and increased availability of transition metals. Dietary deficiencies may also be associated with the decrease in the antioxidant defense mechanisms. Vitamin E is a fat-soluble antioxidant and has the ability to prevent the spread of chain reactions induced by ROS in biological membranes, representing an important defense against oxidative damage caused to the sperm membrane. The objective of this study was to evaluate whether oral supplementation with vitamin E alters bulls fertility and performance of bulls raised in pastures in tropical conditions. We used 16 bulls / Brangus, with a mean of 24 months and 462.2 kg were randomly divided into two groups: GC = Control group (concentrated supplementation without adding vitamin E), vitamin E group GE = (400UI/animal/day supplemented with vitamin E). The animals were maintained on pasture, and supplemented (4,5 kg / animal) with concentrated feed once a day. During the supplementation period 4 samples (days: D0, D30, D60 and D75) were made by electrostimulation. In each collection were evaluated: weight (BW), Diameter (TPER) and Testicular Consistency (TC), Volume (VOL) and concentration (CONC) of the ejaculate, motility (MOT) and vigor (VIG) sperm, percentage of primary defects (PD), secondary (SD) and total (TD), sperm viability (EOS), the integrity of sperm membrane (HYPO) and crossomal (POPE). The experiment was conducted in a completely randomized design. Data were analyzed using ANOVA 5%. It was found BW treatment effect (P = 0.0472), TPER (P = 0.0015), TC (p = 0.0367), EVIG (p = 0.0183) and a trend effect for SD (p = 0.0617). The results obtained in the experimental conditions of this study, it is concluded that oral supplementation with vitamin E, 400UI/day not altered semen quality, however detracted and testicular characteristics of bulls raised on pasture in tropical conditions.
Keywords: reactive oxygen species, oxidative stress, lipid peroxidation.