Evaluation of haematological, serum biochemical and histopathological parameters of growing rabbits fed <italic>Amaranthus dubius</italic>.

Summary: <italic>Amaranthus dubius</italic> is an alternative source of fibre and protein for the feed formulation for growing rabbits, although its effects on their health status are yet unknown. Therefore, this study aimed to evaluate the effects of three dietary levels (0, 160 and 320 g/kg) of <italic>A. dubius</italic> on haematological, serum biochemical and histopathological parameters of fattening rabbits. One hundred and thirteen New Zealand White rabbits were fed ad libitum from weaning (35 days) to slaughter (87 days). The health status of the animals was monitored, and mortality was recorded. Before slaughtering, 30 rabbits were randomly selected for haematological and serum biochemical analysis. During slaughter, 18 rabbits were randomly selected for histopathological study in heart, liver, lung and small intestine. The health status of rabbits was good, with no differences among treatments in mortality. Diet and sex did not affect the values of most haematological and serum biochemical parameters. Fibrinogen, glucose and high‐density lipoprotein values increased significantly from 0 to 320 g/kg <italic>A. dubius</italic> diets. The white blood cell count and glutamic oxaloacetic transaminase values decreased significantly from 0 to 320 g/kg <italic>A. dubius</italic> diets. The organs showed histologically well‐structured tissues. However, in all experimental groups several samples with lesions were observed, always highly focalized in small tissue areas. The main lesions observed, probably related to conditions of thermal stress affecting the rabbits, were cholesterolosis (heart), steatosis (liver), inflammatory lymphoplasmacytic infiltrate (lung) and chronic inflammatory tissue damage (small intestine). In conclusion, the inclusion of up to 320 g/kg <italic>A. dubius</italic> in diet did not jeopardize the health status of growing rabbits. Therefore, <italic>A. dubius</italic> can become an alternative raw material for the formulation of feeds in tropical and subtropical countries where this plant is widespread. [ABSTRACT FROM AUTHOR]