LAUSR

Context A practical, low-cost suggestion for industry to reduce ammonia (NH3) in layer houses is use of Lactobacillus species (L. rhamnosus, L. paracasei and L. plantarum) in drinking water or feed. Thus, we investigated their short-term (8 weeks) use in young layers. Aim A combination of species of Lactobacillus (L. rhamnosus, L. paracasei and L. plantarum at 1.0 × 1012 CFU/kg feed) was provided for laying hens in order to investigate effects on production, nitrogenous compounds in manure, serum chemistry and uric acid in the liver. Method Ninety-six White Leghorns (32 weeks old) were randomly assigned to a control diet (commercial feed) or a diet containing commercial feed + probiotics (g/kg feed: L. rhamnosus 1.667, L. paracasei 0.667 and L. plantarum 0.740) and fed for an additional 8 weeks. Key results No significant major effects were observed among diets on bodyweight, feed intake, egg production or feed conversion ratio. Numerical reductions were noted for feed intake (10%) and feed conversion ratio (9%) at Week 2 for layers receiving probiotics as compared to the control. Ammonia, ammonium-nitrogen (N), total Kjeldahl N and total N in manure were not changed significantly by probiotics, nor did probiotics significantly affect the serum profile (ammonia, uric acid, total protein, albumin and creatine kinase) or uric acid in the liver. There was a numerical but non-significant increase in creatine kinase (11%) after 8 weeks in serum of hens receiving probiotics; likewise, there was a non-significant 8% increase in uric acid concentration in the liver of hens receiving probiotics at the end of the experimental period. Conclusion The probiotics (L. rhamnosus, L. paracasei and L. plantarum at 1.0 × 1012 CFU/kg feed) used in this study did not significantly reduce N-containing compounds in manure of 32–40-week-old layers. Implications Age, different types of layers (and broilers) and mode of administration or concentration of probiotics play important roles in outcomes. Extensive collaborative studies are needed to provide definitive answers for use of probiotics in layer (as well as broiler) feed for reduction of N-containing compounds in poultry houses.