Haemonchus contortus infection affects feed intake and diet digestibility in Creole goats

A study was conducted to evaluate effects of infection with Haemonchus contortus infective larvae(L3; HC) on feed intake, digestibility, faecal egg count (FEC), circulating eosinophils (EOS) and packcell volume (PCV) in Creole goats. The experiment was developed during six weeks althoughmeasurements of intake and digestibility corresponded to 0, 2 and 4 weeks post-infection (WPI)with a single dose of 10,000 L3. Twenty-two parasite-free kids (23.4 ± 0.65 kg BW) were housedand fed once a day (0730 h) in individual boxes. Total faeces collection (with faecal trays placedbehind) and ad libitum forage supply method was used. Dry matter intake (DMI) was dailycalculated. Pooled samples from a 75 d-old Dichantium spp. hay, a supplemental concentrate(100g d-1) and faeces were collected for chemical analyses. Total-tract DM (DMD), OM (OMD), CP(CPD), NDF (NDFD) and ADF (ADFD) digestibilities were determined. Faecal samples were weeklycollected for FEC and were analyzed with a modified McMaster method. Blood samples werecollected once a week by jugular venipuncture to measure circulating EOS and PCV. Data wereanalyzed with PROC GLM of SAS (v. 8.1) considering WPI and animal as fixed and random effects,respectively. Digestibility of CP was not different and was dramatically low (47.1±1.1%), probablybecause kids were draining nitrogen (N) through faeces (larvae, endogenous N) which abnormallycould increase N concentration therefore affecting CP digestibilities values. DMI (537, 639, 599 g d-1), DMD (62.8, 60.4, 62.5%), OMD (64.5, 62.2, 64.0%), NDFD (59.7, 56.2, 62.0%) and ADFD (60.5,53.0, 59.8%) showed significant differences (P<0.05) among the 0, 2 and 4 WPI, respectively. TheDMI was higher and digestibilities lower at the second WPI when animals showed the highest levelof EOS (84.106 vs. 46.106 and 60.106 cells/ mL of blood, for 2 vs. 0 and 4 WPI, respectively) andwere linearly decreasing PCV. These data suggest that the impact of parasitism occur between thesecond and the third WPI, period during which the immune response is more pronounced probablydue to parasite maturation. Further researches are needed to monitor longer term effects onanimals that could immune themselves.