1. The aim of this study was to investigate the effects of a combined probiotic product (Lactobacillus paracasei, L. plantarum, and L. rhamnosus) on egg quality, sulphur compounds in manure and serum biochemistry of second cycle hens. 2. A total of 48 White Leghorn hens, at 52- to 54 weeks of age, were treated in a completely randomised design with water containing 0 or 1.8375 × 1010 cfu/l of probiotics for 8 weeks. 3. Probiotic supplementation did not affect egg quality. Albumen height and Haugh units were in general lowest in week 2 and highest in week 6. 4. For manure and serum parameters, water with or without probiotics produced statistically similar effects. An interacting trend for increasing concentrations of methyl mercaptan in manure was noted for probiotics x week, and should be further investigated. The week of supplementation significantly affected hydrogen sulphide, dimethyl sulphide, and triglycerides.
Keywords: Egg quality; hydrogen sulphide; laying hens; probiotics; reduced sulphur compounds; serum biochemistry.