Metabolismo do edetato de zinco em cordeiros e seu efeito metafilático sobre variáveis metabólicas e oxidativas de ovelhas no pós-parto

Abstract

Sheep rearing is an activity that in the last years has undergone several changes related to the production systems, focusing its search in efficient managements that provide the creation profitability. Among the main obstacles in the activity, the errors in sanitary and nutritional management are directly responsible for the decrease in production, the costs with treatments and the loss of genetic material by death, mainly of fetuses and females in peripartum. There fore microminerals used as nutraceuticals can minimize these losses. In order to evaluate the metabolism of a new source of injectable zinc, called zinc edetate and its effect on metabolic and oxidative parameters in postpartum ewes, two experimental studies were performed. In the first one, six male lambs were used and housed in individual metabolic cages. The animals went through a period of 10 days of adaptation and later were divided into two experimental groups. Three animals received a dose of 3mg/kg (2ml) of zinc edetate subcutaneous (SC), being considered the treated group (GT), and other three animals received the same dose of 0.9% sodium chloride solution by the same route, being denominated control group (CG). After the adaptation period the animals were monitored for 30 days to determine the production of faeces and urine and the zinc excretion was measured. During the first 7 days, blood samples were collected for the determination of serum zinc. After this initial period, the blood collections were performed on interspersed days up to 30 days. Water and food samples were also collected to determine the diet concentration of zinc. At the end of the study, the animals were submitted to euthanasia, where 5 grams each of liver, muscle (Longissimus dorsi), heart and kidney were collected in order to determine the concentration of tissue zinc. At the end of the experiment, it was concluded that the zinc edetate presented a greater urinary excretion than the fecal one, as well as being the main route of elimination of this mineral. The use of zinc edetate did not alter the concentrations of this mineral in the tissues and blood of the animals, but presented a higher apparent absorption and retention of this mineral. In the second study, which aimed to evaluate zinc edetate on metabolic and oxidative variables in ewes in the immediate postpartum period, 26 Texel ewes, raised extensively, aged 3 to 4 years, with pregnancy confirmed by ultrasonography at 45 days of gestation, and with mean body score 3.0 were used. Only sheep with simple gestation distributed in two experimental groups were used in the study: the animals in the treated group (GT; n = 13) received 100mg of zinc edetate SC (2mL) 15 days before the expected delivery date and the group control (CG; = 13) received 2mL of 0.9% sodium chloride solution SC at the same date as GT. Blood samples were collected 15 days before the expected delivery date and immediately after delivery for evaluation of the effect of zinc edetate. The 20mL of blood sample was collected in a silicone tube without anticoagulant. The levels of insulin-like growth factor (IGF-1), fructosamine, cholesterol, triglycerides, and oxidative stress index were obtained by measuring the total antioxidants and oxidants, and the blood levels of zinc. There was no difference in oxidative metabolic parameters between the experimental groups (P> 0.05) as well as in blood zinc concentrations (P> 0.05). Zinc edetate had no action on metabolic and oxidative variables in the postpartum period of sheep with reduced metabolic challenge.