Effect of pH-lowering litter amendment on animal-based welfare indicators and litter quality in a European commercial broiler husbandry

ABSTRACT Several studies have shown that litter moisture is a major reason for foot pad lesions (FPD) and promotes microbial growth of nitrifying bacteria. The aim of the current study was to determine the possible effects of a sodium bisulfate complex (SBS) as a litter additive on FPD, hock burn (HB), and litter parameters. Two application rates of SBS were examined in 2 experiments on a commercial farm. Two groups of about 30,000 broiler chicks each were introduced on spelt granulate spread at 700 g/m² and kept for 36 d. In the first experiment (TRT1), 250 g/m² SBS was spread on top of litter 20 h before chick placement; in the second experiment (TRT2), SBS was reduced to 150 g/m². Each experiment consisted of 1 treatment group (SBS) and a control group without treatment (CON). Both experiments were repeated once. Litter parameters (pH, percentage of dry matter), foot pad, hock condition and body weight of randomly sampled birds (n = 60 per group) were recorded weekly. Mortality rate was higher in SBS groups compared to CON groups (TRT1 2.79 vs. CON 2.03%, TRT2 2.88 vs. CON 2.27%). SBS had no effect on body weight averaged over the whole production period (P > 0.05). Incidence of FPD was significantly reduced in both groups treated with SBS compared to CON (P < 0.05), with group TRT1 showing the best results. Incidence of HB was not affected by SBS (P > 0.05) but by dry matter content (P < 0.05). At the beginning, SBS reduced litter pH to 1.7 and 2.0 in TRT1 and TRT2, respectively, compared to 6.5 and 6.7 in CON. Litter pH in TRT groups increased over time and approached pH of control groups by day 15. Results of the current study indicate that SBS treatment may be beneficial regarding foot pad health in broilers. However, further studies are needed to investigate alternative SBS application rates, and to verify the results.