Computed tomography and radioactive 32P detected phosphorus impairment in metabolism, reduced bones density and animal performance caused by mixed infection of Haemonchus contortus and Trichostrongylus colubriformis in sheep

Abstract

Phosphorus (P) is one of the main minerals present in the animal body and exerts crucial functions in the organism. P is present at all cell membranes and integrates the structure of bones, being necessary its supplementation in ruminants due to the deficiency of this mineral in the pastures. One of the principal factors that compromise its metabolization are gastrointestinal nematodes (GIN). Thus, the objective of this study was evaluate the performance and metabolism of P through its distribution in the animal body, density of bones and muscles, dynamic fluxes, biological availability and half live of P, concentration of P in tissues and bones of lambs simultaneously infected with the most prevalent GIN to sheep, in tropical or subtropical areas, (Haemonchus contortus and Trichostrongylus colubriformis) using the isotopic dilution technique with ³²P radioisotope. Twenty Santa Ines sheep with seven months of age and averaging initial weight of 30.8 ± 6.41 kg were used and allocated to one of two treatments. Ten animals were orally infected (a single dose of 30,000 L3 larvae of T. colubriformis + 10,000 L3 larvae of H. contortus), and ten animals were not infected (control group). During the experimental, samples of blood, feces, urine, and diet refusals were collected and weighting were performed. A computed tomography was performed twice, before infection and at the end of the experiment, to evaluate changes in body composition. On 64-d after experimental infection, animals received an intravenous injection of ³²P solution, and 7-d after they received radioisotope injection. The experimental animals were slaughtered, and tissue and bones were collected for P concentrations. The results showed that the parasitic infection compromised the absorption of P, impairing the metabolism, decreasing the mineral bioavailability increasing P bones reabsorption, and reducing bones density, also negatively compromising the infected animal performance.

Keywords: Endoparasites; Gastrointestinal nematodes; Lambs; Minerals; Radioisotope.