Abstract This study was conducted to evaluate the effects of various combinations of Lactobacillus species (L. rhamnosus, L. paracasei, and L. plantarum) on closely associated variables of production of laying hens, nitrogenous compounds in manure, the serum concentration of specific chemicals, and liver uric acid (UA) concentrations at peak lay. White Leghorns W-36 (32-week-old) were randomly assigned to five treatments for 8 weeks. Treatments were T1, the Control, a commercial feed; T2, the Control + L. paracasei + L. plantarum; T3, the Control + L. paracasei + L. rhamnosus; T4, the Control + L. plantarum + L. rhamnosus and T5, the Control + L. paracasei + L. plantarum + L. rhamnosus. Each bacterial species was included at 3.33 × 1011cfu/kg feed for a total of 6.66 x 1011 cfu/kg feed for T2–T4 and a total of 1.0 × 1012 cfu/kg feed for T5. Major effects among combinations of probiotics on production were not noted. The interaction of Probiotics by Week (Probiotics*Time) affected feed intake (P = 0.0007) and feed conversion ratio (FCR, P = 0.0049) due to fluctuation by week. Significant effects of time were also recorded for a gradual increase in body weight (BW, P = 0.0007); lowest and greatest feed intake at weeks 2 and 7, respectively (P < 0.0001); an increase in egg production (P = 0.0007) and maximum FCR at week 7 (P < 0.0001). Ammonia (NH3) concentration, ammonium nitrogen (NH4–N), total Kjeldahl nitrogen (TKN), and total nitrogen remained unaffected at P < 0.05. Although there were fluctuations, a trend emerged for the reduction of TKN. Combinations of probiotics did not affect NH3, UA, total protein (TP), albumin (ALB), creatine kinase (CK), and UA in the liver. Temporal (Time as a fixed effect) effects were noted for all nitrogenous compounds present in manure. For ammonia, temporal effects were significant due to fluctuation over time. Week 0 had the lowest value followed by weeks 4 and 8. Week 6 had the greatest value. For ammonium nitrogen, week 8 had the lowest value followed by week 0 and 4 with the next highest value. Week 6 had the greatest value. For TKN, week 4 had the lowest value followed by weeks 6 and 8. Week 0 had the greatest value. For TN, weeks 4, 6, and 8 had similar and lowest values followed by week 0 having the greatest value. However, an overall reduction in NH4-N, TKN, and TN was noted. Fluctuations in NH3 (P = 0.0033) and CK (P = 0.0085) were noted for Time. There was also a trend (P = 0.0706) for the increase of UA in serum. Two or more species of probiotics with yeast should be investigated. If the combination is applicable for increasing production measurements and reducing nitrogenous and serum compounds, the most appropriate time to feed the probiotics from day 1 to the end of production should be investigated.