Phosphorus modelling in lambs submitted to experimental infection with Trichostrongylus colubriformis with the use of 32P

Author(s)

Tairon Pannunzio Dias e Silva

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
• Defense date: 2017-03-07

Examining board members

Helder Louvandini; Ricardo Lopes Dias da Costa; Solange Maria Gennari; Débora Botequio Moretti; José Cleto da Silva Filho

• Advisor: Helder Louvandini

Abstract

Aiming to evaluate hemato-biochemical variables, apparent digestibility and performance as well as the metabolism and kinetic of phosphorus (P) in lambs experimentally infected with Trichostrongylus colubriformis, two experiments were conducted. At the first study, 18 male lambs were distributed in two experimental treatments: infected group (I, n=9) and control group (C, n=9) unaffected. Infected lambs received approximately 5000 T. colubriformis infective larvae (L3), three times per week, during three weeks, totalling 45 000 T. colubriformis L3. The control of daily feed intake was performed (pair-fed). Data of live weight, body condition score and samples of blood and faeces were collected fortnightly, during 75 days to analyze the hemogram, biochemical variables and faecal egg count (FEC), respectively. In addition, apparent digestibility and ruminal parameters of lambs were determined. Lambs presented moderate infection (FEC = 620.3 ± 594.98) with decreased erythrocytes, haemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin concentration and total protein. On the other hand, increased platelets counts as well as the amount of circulating eosinophils when compared to the group C (P < 0.1). The voluntary intake of infected lambs was not altered, but there was lower dry matter digestibility. It was concluded that T. colubriformis infection altered haematological and biochemical parameters. It did not interfere in dry matter intake, but decreased digestibility in infected lambs. In the second study, the objective was to study the metabolism and kinetic of P in lambs experimentally infected with T. colubriformis using isotope dilution technique and modelling. For this, 15 lambs distributed in the infected treatment (I, n=8) e control (C, n=7) as described above were used. After 66 days of the last inoculation was injected 6.6 MBq of 32P/lamb to evaluate the kinetics of the mineral. Blood, faeces and urine samples were collected in the following seven days and the slaughter of lambs was carried out on the last day in order to collect bone and soft tissues (Liver, kidney, heart and muscle) samples. To analyze P flows the biomathematical model described by Lopes et al. (2001) was used. Similar P intake between treatments was verified (VI) (P > 0.1), lower absorption of endogenous (Vaf) and dietary P (Vaa) as well as higher excretion of dietary P (VFD) in infected lambs (P < 0.1). With the lower absorption (VaT) of P in infected lambs, there was, consequently, lower distribution and lower incorporation of P in the bones (VO+D). It was concluded that P metabolism of lambs infected with T. colubriformis was altered, with reduced intestinal absorption and bioavailability, increased faecal loss and reduced P flow to bone (AU)

• FAPESP's process: 14/05023-1 - Phosphorus modeling in sheep submitted to experimental infection with Trichostrongylus colubriformis with the use of 32P
• Grantee: Tairon Pannunzio Dias e Silva
• Support Opportunities: Scholarships in Brazil - Doctorate