Parâmetros hematológicos, bioquímicos e zootécnicos de bezerros leiteiros submetidos a administração do imunoestimulante pegbovigrastim

Abstract

One of the main limitations of bovine milk production occurs in the calf stage, due to the high occurrence of diseases, mainly of the gastrointestinal and respiratory tract. Therefore, this study aimed to evaluate the administration of the pegbovigrastim immunostimulant on the hematological parameter, biochemical and zootechnical parameters of dairy calves, and its response to lipopolysaccharide (LPS) challenge. In order to do this, two experiments were carried out. Twenty newborn Holstein calves were divided into two groups: Imrestor group (IMR, n = 10) with subcutaneous administration (SC) of 25 μg/kg of live weight of pegbovigrastim and Control group (CTR, n = 10) receiving a placebo (0.9% saline solution) administration, both on the 10th day of life of the animals. Blood samples were collected on days 10, 12 and 14 in relation to the birth to analyze the biochemical and hematological parameters, and zootechnical evaluations were performed on days 0, 7, 14, 21 and 60 of age. It was observed that there was an increase in the number of total leukocytes (P < 0,0001) in the IMR group on days 12 and 14 in comparison to the CTR group, as well as the counts of segmented neutrophils (P < 0,0001), band neutrophils (P < 0,0001), and monocytes (P = 0,0002). No differences were observed in the other haematological (P < 0,05), biochemical (P < 0,05) and zootechnical (P < 0,05) parameters analyzed. In the second experiment, 20 Holstein calves were used up to sixty days old, divided into four groups: group 1 (LPS, n = 5) receiving a single intravenous application of Escherichia coli LPS on day 0, at a dose of 0.25 μg/kg body weight; group 2 (IMR, n = 5), who received an SC application of pegbovigrastim on day 1 in relation to the LPS application at a dose of 25 μg/kg body weight; group 3 (IMR + LPS, n = 5), which received an LPS application at a dose of 0.25 μg/kg on day 0, and 25 μg/kg of live weight of pegbovigrastim on day 1; and group 4 (CTR, n = 5), who received a placebo dose of 0.9% sodium chloride via EV on day 0 and another SC dose on day 1. For the analysis of biochemical and hematological parameters, blood samples were collected on days -1, 0, 1, 2, 3, 4, 8, 14 and 21 which relate to LPS challange. An increase in the number of total leukocytes (P < 0,0001) was observed in the IMR, IMR + LPS and LPS groups, and the IMR group remained with the highest number of cells from day 2 to day 21. The levels of paraoxonase 1 (P = 0,02) were higher in the IMR group compared to all others. The administration of IMR did not alter metabolic parameters that were fundamental for the hepatic, renal and proteic functioning of the calves (P > 0,05). Studies have shown that the administration of pegbovigrastim increases the number of circulating neutrophils, without affecting biochemical and zootechnical parameters of the animals.