Trichostrongylus colubriformis infection negatively impacted phosphorus metabolism of lambs

Abstract Intestinal endoparasite infection may promote a nutrient competition with host, reducing absorption and performance as consequence. Phosphorus could be more affected due to the main absorption site is the duodenum. Thus, the study measured the performance, phosphorus metabolism, bone density and blood markers in Santa Ines lambs infected Trichostrongylus colubriformis and fed with different phosphorus (P) levels were tested. Eighteen healthy six-month old, castrated male, Santa Ines lambs (initial body weight 22.4 ± 2.7 kg) were randomly assigned to 4 treatments in a 2 × 2 split-plot arrangement. Treatment factors were sufficient (SP) or deficient (DP) dietary P and uninfected (ui) or infected (i) resulting in 4 treatments: SPui, DPui, SPi, and Dpi). Five animals were assigned to each of the infected treatments and 4 to the uninfected treatments. Infection was established using a single oral dose of 40.000 T. colubriformis in the larval stage (L3). All the animals were fed Tifton 85 hay (Cynodon spp.; 60 %) supplemented with cassava and maize gluten meal (40 %). Animals were weighed and blood was sampled weekly. Body composition was estimated twice by computed tomography. P metabolism was assessed by isotope dilution after a bolus infusion of 32P (7.4 M Bq/0.5 mL). Fecal egg counts (FEC) were assessed every 3 days beginning d 18 post-infection, and adult nematodes were counted and characterized (gender, length, and eggs in reproductive tract) at slaughter. The experiment lasted 96 d, and 45 d after infeciton. Statistical procedures were performed using R studio. Infection was successful as evidenced by increased FEC, and the elevated counts were maintained longer with Dpi than SPi. Performance, feed intake, and blood parameters were not affected by treatments. Infected animals had reduced bone density and bone P concentrations as compared to uninfected ones. Endogenous P loss was reduced for DP. Plasma, saliva, and ruminal liquid P concentrations decreased in infected animals. Phosphorus absorption and retention coefficients did not differ by treatment, but the biological half-life (T1/2) of P was reduced for infected animals due to faster blood 32P removal. We concluded that T. colubriformis infection modified P metabolism, and blood P concentrations are an indicator of animal problems, connecting infection and bone mineralization.