Abstract:
Japanese quails in domestication lack broody tendency hence adoption of artificial incubation for commercial production. Inappropriate Incubation Temperature-IT affects hatchability and sex determination in quails. Conventional IT and sexing techniques used for other poultry species cause low hatchability, survivability and inaccurate sexing. Information on optimum IT and in ovo sex predetermination in quails is inadequate. Therefore, optimum IT determination and effects of its alteration on sex reversal, hatchability and post-hatch performance of Japanese quails were assessed.
Clutch of 1,605 eggs were randomly allotted to incubators at 36°C (T1), 37°C (T2), 38°C (T3), 39°C (T4) and 40°C (T5) for optimum IT determination. At hatch, incubation period and hatchability were recorded. Chicks were reared for six weeks, feed intake and survival rate were recorded. Six chicks/treatment were randomly selected and sacrificed to obtain carcass weight. Another clutch of 1,260 eggs were incubated at 38°C (TA, Control) without pausing, 36°C (TB), 37°C (TC), 38°C (TD), 39°C (TE) and 40°C (TF) paused for five hours on days 3, 4 and 5. Also, 612 eggs were set at 38°C (TI, Control) without pausing, 36°C (TII), 37°C (TIII), 38°C (TIV), 39°C (TV) and 40°C (TVI) paused for five hours on days 11, 12 and 13. At hatch, hatchability was recorded. At week three, the chicks were sexed based on plumage pattern and reared separately. At week six, survival rate was determined, six birds per treatment were sacrificed and testes/ovaries were observed for sex confirmation. Non-conformity with the male/female plumage pattern was considered reversed sex. Data were subjected to descriptive statistics and ANOVA at α0.05.
Hatching commenced on day 16 (T4), 17 (T3), 18 (T2, T5) and 20 (T1). Hatchability was 36.9±13.8% (T2), 36.6±9.8% (T4), 35.9±28.7% (T3), 30.6±19.9% (T5) and 23.9±26.6% (T1). Feed intake varied significantly and ranged from 10.2±5.29g (T2) to 19.3±0.19g (T1). Survival rate was significantly higher in T5 (66.5±6.4%) than in T4 (46.1±10.0%), T2 (27.4±1.0%), T3 (21.5±3.7%) and T1 (14.5±0.0%). Carcass weight was significantly higher in T1 (97.4±0.1g) than in T3 (80.0±14.2g), T5 (77.1±16.9g), T4 (74.3±9.58) and T2 (68.1±11.4g). Hatchability was higher in TA (81.0±50.9%) than in TC (46.0±17.7%), TB (43.1±14.0%), TE (12.5±9.2% and TD (1.5±1.8%), while hatchability failure was recorded in TF. Survival rate was similar in TA (49.2±42.7%), TC (38.9±1.6%) and TB (22.2±14.1%), while none survived in TD and TE. Male/female ratio was 40:37 (TA), 10:9 (TB) and 10:11 (TC) without sex reversal. Hatchability was 81.2±14.7%, 70.9±52.3%, 68.0±18.9% and 62.7±6.6% in TI, TIV, TIII and TII, respectively, while both TV and TVI had hatchability failure. Survival rate was similar in TI (59.2±17.7%), TIII (55.9±5.2%) and TIV (54.4±18.4%) but higher than 18.7±5.6% (TII). Male/female ratio was 7:12 (TI), 7:4 (TII), 10:13 (TIII) and 0:10 (TIV) without reversed sex.
Low temperature (36°C) prolonged incubation period, enhanced feed intake and carcass weight, while high temperature (40°C) enhanced survivability. However, 39°C at which hatching commenced on day 16 may be recommended as optimum incubation temperature for Japanese quails. Paused incubation temperature did not elicit sex reversal and caused hatchability failure.
