Growth Response of New Zealand White Rabbits to Dietary Probiotic and Vitamin C under Tropical Humid Climate

The study was conducted to evaluate the effect of supplementing Lactobacillus casei and vitamin C on growth performance of New Zealand White rabbits affected by heat stress during summer seasons between March and May in Kerala state, India. Twenty four two month old rabbits (average body weight 0.91kg) were distributed to four groups of six rabbits each. The treatments were control group (C) fed basal diet alone, L group fed basal diet along with Lactobacillus casei (106 colony forming units per g of feed), V group fed basal diet along with ascorbic acid (200 mg per kg feed), and LV group fed basal diet along with L. casei and ascorbic acid at the same rate as in V and L. The Temperature humidity index (THI) values in the rabbitry and rabbit fecal cortisol values (n=6 per group) were estimated to assess the heat stress level in rabbits. As per THI values, animals were exposed to stress (THI > 27.8) in the afternoon hours during the entire experimental period. The V, L and VL rabbits had lower mean cortisol level than control during the period of very severe and severe heat stress (1-9th experimental week- March and April). The groups did not differ for body weights during the period of very severe and severe heat stress (March and April). The V, L and VL rabbits had similar 21 week final weights but those of the L and VL rabbits were 25.52% and 32.29% higher than the control. The rabbits in the V, L and VL group showed 38.51%, 49.19% and 61.13% (P 0.05) the overall feed intake. Cost of production (Rupees) per kilogram live weight on feed basis was lowest for VL animals followed by L and V animals respectively.