Floor space and betaine supplementation alter the nutrient digestibility and performance of Japanese quail in a tropical environment

This study investigated the effects of floor space and betaine supplementation on the nutrient digestibility and performance of laying quail, at an advanced stage of production, in a tropical environment. In total, 408 laying quail (23 weeks old) were distributed in 3 x 2 factorial arrangements with four replicates. The first factor was floor space (250 cm(2) [FS-1], 221 cm(2) [FS-2], and 200 cm(2) per bird [FS-3]) by allocating 15, 17, and 19 birds per cage (cage size: 3750 cm(2)). The second factor was betaine supplementation, administered at levels of 0 (Control) and 0.12% (Betaine). The birds were housed under a natural, tropical environment that was outside the predominant thermoneutral zone, indicating heat stress conditions. Interactions were found between floor space and betaine on crude fiber digestibility, egg production, and eggshell thickness, with the highest values being yielded in FS-2 group supplemented with betaine. Reducing the floor space to 200 cm(2) negatively affected nutrient digestibility and performance. The birds kept in FS-3 had lower (P < 0.05) dry matter, crude protein, crude fat, and calcium digestibility values than those kept in FS-1 and FS-2. Birds housed in FS-2 exhibited higher egg weight than those in FS-3 (P < 0.05), although they did not differ from those in FS-1. Furthermore, a lower eggshell weight in FS-3, compared with FS-1 and FS-2, was observed (P < 0.01). Betaine supplementation enhanced the dry matter, crude protein, crude fat, crude ash, and calcium digestibility values (P < 0.05). Accordingly, betaine improved feed intake, egg weight, feed conversion, and protein and energy efficiency ratios (P < 0.01). Betaine also resulted in higher albumen, yolk, and eggshell weights (P < 0.01). In conclusion, a floor space of 221 cm(2), combined with betaine supplementation at 0.12%, can be applied for raising quail under high environmental temperatures.