Effects of low-protein diets on growth performance and carcass yields of growing French meat quails (France coturnix coturnix)
A dose-response experiment with 5 analyzed dietary crude protein (CP) levels (17.61, 19.73, 21.58, 23.24, and 25.32%) was conducted to investigate the effects of low-protein diets on growth performance and carcass yields of French meat quails from 15 to 42 d of age. All diets were formulated to contain a similar dietary energy level and amino acid profile. A total of 400 fifteen-day-old French quails were divided into 5 experimental treatments and each treatment contained 4 replicate pens of 20 birds (10♂+10♀). At 42 d of age, weight gain, feed intake, CP intake, feed/gain, and the yields of breast part with bone, leg part with bone, and liver of quails from each pen were measured. The results showed significant effects of the low-CP diets on CP intake, weight gain, feed intake, and feed/gain at different experiment periods except for the sixth wk of age (P < 0.05). In addition, as dietary CP decreased from 25.32 to 17.61%, feed intake and feed/gain were increased linearly (P < 0.05), whereas CP intake showed the opposite trend and decreased gradually. On the other hand, the carcass yields of quail were not influenced by reducing dietary CP at 42 day of age (P > 0.05). Based on broken-line regression, 23.0%, 22.5%, and 20.4% were the minimum dietary CP to keep weight gain similar to the quails fed with 25.32% CP diets during the third, fourth, and fifth wk of age, respectively. In summary, with crystalline amino acid supplementation based on a similar amino acid profile, it was possible to formulate the low-protein diets containing about 22.0% CP for growing meat quails without adverse effects on growth and carcass yields of meat quails.