Processing of rubber seed and feed formulation
The mature rubber seed was harvested, dehulled and boiled the kernel at 90-100°C for one hour. The boiled kernel was sun dried at open air until visually seems to be completely dried. Then, the dried kernel was ground to powder by a hand grinder and has been termed it RS. The proximate composition; % H2O, % crude protein (CP), %crude fiber (CF), % ether extract (EE), % ash and % nitrogen free extract (NFE) of RS was determined by Kjeldahl method following the procedure of AOAC (1990). The ME content of RS was calculated using the formula ME (Kcalkg-1) = {(EE*2.25 +CP + NFE) X 3520}/100 (Fraps et al.,1940). The diets were iso-caloric and iso-nitrogenous, where D0 was the control diet containing 20% soybean meal (SM) and 4% soybean oil (SO), and D1,D2, D3and D4 were the diets that 12.5%, 25%, 37.5% and 50% of SM, and 25%, 50%, 75% and 100% of SO, respectively of the control diet had simultaneously been replaced by RS. The desired nutrient concentration in the diet for the growing quail (NRC, 1994) has been balanced using a locally developed Microsoft Excel-based computer software for ration formulation.
Experimental birds and management
Forty-five 1-week-old apparently healthy quail collected from BAU (Bangladesh) Poultry Farm Hatchery were randomly and equally allocated to five experimental diets having 3 replications of each. A battery type 3-tier growing quail cage was used in this experiment, where each tier had 3 pens of equal floor space of 120 square inch for 3 birds. To prevent the bird from escaping out of the cage, the pens were wrapped properly with wire net. The birds under all dietary groups were supplied with the equal and required amount of dry mash feed until 35day of age. Clean drinking water was supplied to the bird ad libituma long with other standard management condition.
Record keeping and determination of the carcass characteristics
Survivability of the bird, daily feed intake (FI), and weekly body weight (BW), feed cost and carcass characteristics were investigated and recorded. At the end of experiment, two quails from each pen, thus six quails under a treatment, were randomly selected and dissected. The weight of the dressed carcass, blood, feather, skin, shank, kidney, liver, heart, proventriculus, gizzard, and ovary were recorded. The length of the cecum and any abnormal symptom found in the bird was recorded. All weights were measured using digital balance (Minidigital 300g, ST Model, Guangdong, China). The dressing yield related parameters were converted to the percentage of live of the quail before slaughter.The mean of the parameters among different dietary groups were statistically analyzed in a completely randomized design using the Genstat computer package (Lawes Agricultural Trust, Rothamsted Experimental Station). The linear regression analysis was done to predict the response of different parameters to RS inclusion in the diet. Significant differences were considered at P<0.05.