Avaliação de alcaloides isoquinolínicos no controle da diarreia experimental por Cryptosporidium parvum em bezerros

Abstract

Cryptosporidium infection is one of the most prevalent causes of diarrhea in calves. On the other hand, diarrhea in neonatal calves corresponds to one of the main economic obstacles in bovine breeding. As a strategy to minimize the damages caused by diarrhea, the use of antibiotics added to food has been used to raise calves. However, to date, no drugs have been able to effectively treat Cryptosporidium infection. There is a worldwide trend today to identify alternative, natural and sustainable substances to replace traditional medicines used in animal production. This is due to international requirements in the market for animal products, which increasingly restrict the use of antimicrobials in production animals. In this way, potential substances for use with this purpose are currently targeted for research. In this context, isoquinolinic alkaloids may be an alternative based on their anti-inflammatory, antimicrobial and antioxidant properties that may promote intestinal health. The objective of this study was to evaluate the prophylactic use of a standardized extract of Macleaya cordata containing isoquinoline alkaloids that were added to milk in order to control cryptosporidiosis in neonatal calves experimentally inoculated with C. parvum oocysts. Another objective was to verify the presence of other enteropathogens associated with C. parvum and to relate the effects of the additive on clinical, hemogasometric, hematological and serum biochemical parameters of the animals. Twenty-six Holstein calves were distributed in two groups: SG (diet supplemented with 10g / day of the standardized extract of M. cordata) and CN (control diet, without additives). SG calves had a greater average weight gain between days 14 and 21, with no mortality and with reduced intensity and duration of diarrhea. In contrast, calves of the CN group had more severe acid-base disorders, required more hydration support therapy and had a mortality rate of 15.4%. Other potential enteropathogens such as coronavirus, Salmonella spp, E. coli (ETEC) and Giardia spp. in associations with Cryptosporidium in both groups with similar frequencies. The calves of both groups presented dehydration and compensated metabolic acidosis with greater intensity in the CN group. In the CN group, significant reductions in cholesterol and serum iron concentrations were observed, as well as worse leukogram parameters. These results suggest that the isoquinolinic alkaloids added to calves' milk decreased the intensity and duration of clinical signs and reduced the need for supportive therapy as well as the mortality rate of the animals. In addition, the presence of the additive in the diet was beneficial for the animals during episodes of diarrhea based also on clinical and laboratory parameters, so this may be an alternative strategy to minimize the consequences of the disease.