The present study was carried out with a view to investigate the production performance of layers fed with probiotic in diets at different concentration 0 (T1), 50 (T2), 100 (T3) and 150 g (T4) per ton of basal diets during post peak production (47 to 58 weeks of age). The basal diet was formulated with commonly available feed ingredients like maize, soybean meal, sunflower meal, de-oiled rice bran, fish meal as per the specifications of BIS, (1992) suitable for Indian conditions. The chemical composition (%) of the basal diet was 90.0 (DM), 18.09 (CP), 2.82 (EE), 7.65 (CF), 55.22 (NFE), 17.22 (TA) and 3.81 (AIA). The calculated ME content of the basal diet was 2654 Kcal/Kg. One hundred and eighty Single Comb White Leghorn layers were used in the experiment and divided into four dietary treatments with three replicates of fifteen birds each. During the experimental period feed intake, feed efficiency and body weights were recorded in three periods of 28 days each (47 to 50, 51 to 54 and 55 to 58 weeks). Serum parameters like total serum proteins and serum cholesterol levels were recorded at the start and at the end of the experiment. There was no significant difference observed in feed intake (g) during overall experimental laying period (47-58 weeks) and feed intake ranged from 118.53 (T4) to 120.18 g (T1). There was no significant difference in feed efficiency (kg feed consumed for dozen eggs) during 47-58 weeks of age. Better feed efficiency (kg feed consumed for dozen eggs) was observed in T2, T3 and T4 groups (1.68 Kg) over T1 (1.69 Kg). Similarly non-significant differences were observed in birds fed with experimental diets with regard to feed efficiency expressed as Kg feed consumed for Kg egg produced. The total protein was reduced by 7.33% in control (T1) but increased in T2, T3 and T4 by 2.60, 1.19 and 2.58% respectively. There was no significant difference observed among the treatment groups. The serum cholesterol increased by 0.56% in control (T1) but reduced in T2, T3 and T4 by 2.39, 6.22 and 8.82% respectively. During 47-58 weeks of age significantly (p ≤ 0.05) higher body weights (g) were observed in T1 (1296) and lower body weight was observed in T4 (1234) group. There was no significant difference in feed consumption and income over feed cost per 12 eggs produced among different treatments. Income over feed cost/12 eggs in T1, T2, T3 and T4 were 4.91, 5.13, 5.09 and 5.06 respectively. Percent improvement in income over the control (T1) was T2 (4.51), T3 (3.83) and T4 (3.14). There was no mortality observed in all the groups during the experimental period and birds did not show any illness on probiotic addition. Better performance of the birds, reduced cholesterol contents and improved relative economics over control suggest that 50g of probiotic addition to one ton of layer diet is beneficial without any adverse effects during post peak production. The inclusion of probiotics can replace the usage of antibiotics in poultry feeds.

Keywords: Probiotic; Layers; Post peak production; Feed efficiency; Serum cholesterol; Serum protein.