South African Journal of Animal Science
On-line version ISSN 2221-4062
The effect of administering low (15 mg/L) levels of silver nanoparticles in the drinking water of broilers (n = 40) was investigated as a potential replacement for antibiotic coccidiostats (Salinomycin® or Baycox®) in two trials. Four treatments were used: (1) challenged (with 3.3 x 105 Eimeria tenella oocysts via oral gavage in the first trial and 1.6 x 104 in the second trial) and medicated with silver nanoparticles in drinking water; (2) challenged and medicated with a registered ionophore coccidiostat (Salinomycin® in Trial 1 and Baycox® in Trial 2); (3) challenged and unmedicated and (4) unchallenged and unmedicated (control). Caecal lesions were scored on a scale from 0 - 4, while liver, caecal and kidney samples were taken to determine silver content. Growth performance was subjected to ANOVA using Statistica®. In Trial 1, neither the challenge (587 g vs. 561 g) nor the use of silver nanoparticles (587 vs. 555 g) had a significant effect on the weight gain of chicks from 13 to 27 days of age. The coccidiostat treatment group had a significantly lower weight gain than the unmedicated control (219 vs. 560.5 g) but had the lowest lesion score of 2.3. The silver nanoparticles group had, numerically, a slightly better score than the untreated group. The unchallenged control group had scores of 0. In the second trial there were no significant differences in growth performance between the treatments and there were no lesions, but both the silver nanoparticles group and the coccidiostat group had 50% less oocysts in the faecal samples compared to the control group. The silver content of the livers of the silver nanoparticle group was 0.083 mg/kg compared to 0.001 mg/kg in the control group. The results of this study on the use of silver nanoparticles as a coccidiostat were therefore not conclusive, but holds promise so that further investigation is warranted.
Keywords : Ag; protozoa; oocysts; silver retention; nano technology.