Optimum levels of protein and energy in diet for crossbred native chicken (Pradu Hang Dam × JA 57 Ki)

Abstract

The research was conducted in 3 experiments (Exp.) using crossbred native chicken (Pradu Hang Dam x Hubbard JA 57 Ki) as an experimental animal. The diets contained 2 levels of CP. Each CP level containing 3 levels of ME according to a 2x3 Factorial in Randomized Complete Block Design (RCBD), having CP and ME as 2 major factors, while the sex of birds was considered as a block. Exp. 1 studied in 3 growing periods of chicks, i.e. 1-5, 6-10 and 11-13 weeks of age (WOA). A total of 1 day old 1,440 chicks with an equal number of male and female, i.e. 720 birds/sex was used. Each sex was randomly allotted to 6 groups of 3 replicates, containing 40 birds/rep. They were fed with diets containing 21 vs. 19, 19 vs. 17 and 17 vs. 15% CP during 1-5, 6-10 and 11-13 WOA, respectively. Each CP level contain 3.2 vs. 2.9 vs. 2.6 kcal ME/g throughout the experiment. The result of the whole raising period showed that there was highly significant interaction (P<0.01) between CP and ME levels on all parameters of performances, except on mortality and culling rate. High CP diets gave higher BWG, ADG, CP and lysine intake, but lower FI and ME intake with better FCR and FCG (P<0.05). It also gave higher percentage of carcass and drumsticks, but lower percentage of gizzard than the low CP diets (P<0.05). Higher ME diets (3.2 and 2.9 kcal ME/g) gave significantly higher BWG and ADG with lower FI, thus gave better FCR and FCG. It also gave higher percentage of carcass and abdominal fat, but lower percentage of gizzard than the 2.6 kcal ME/g diet (P<0.05). Male had significantly higher BWG, FI and all nutrient intake, but lower percentage of breast meat than female. However, sex had no influence on FCR, FCG, mortality rate and other carcass composition. The optimum feed ration for the whole experimental period was 21-19-17% CP with 3.2 kcal ME/g. However during the first 5 WOA, it may contain 19-21% CP with 3.2 kcal ME/g, while during 6-10 WOA should contain 19% CP, 3.2 kcal ME/g and during 11-13 WOA should contain 17% CP, 2.9 kcal ME/g, due to the highest production performances and the lowest feed cost per kg BW gain as compared to the other feeds. However, this result might be slightly bias, due to the influence of the diets in the earlier periods on the growing and finishing periods. It needs to be rechecked in the next 2 experiments when the same diet was fed to the chicks prior to the onset of each experiment.Exp. 2 was conducted during 6-10 WOA. The total of 1,700 heads of 1 day old chicks composed of 50% male and 50% female were fed with diet containing 19% CP, 3.2 kcal ME/g until 5 WOA. Then 1,440 heads of healthy chicks composed of 720 males and 720 females were used. Each sex was randomly allocated into 6 groups of 3 replicates containing 40 birds/rep. They were fed with diets containing 19 or 17% CP. Each CP level contained 3 energy levels i.e. 3.2, 2.9, or 2.6 kcal ME/g. The result revealed that no significant interaction between CP and ME on all parameters. Dietary CP level had no significant effects on BWG, ADG, FI, FCR, FCG and carcass composition (P>0.05), except the CP intake decreased by the low CP diets. The highest ME diet (3.2 kcal ME/g) gave significantly higher BWG and ADG with the lowest FI, thus caused better FCR and FCG than the lowest ME diet. In addition, the higher energy diets (3.2 and 2.9 kcal ME/g) gave significantly higher percentage of carcass, breast meat and abdominal fat, but lower percentage of liver and gizzard than the 2.6 kcal ME/g diet. Male had significantly higher BWG, ADG, FI and all nutrient intake with better FCR and FCG than female. In addition, male also had significantly higher percentage of carcass, thighs, drumsticks, butsignificantly lower percentage of wings and liver than female. The proper ration for Pradu Hang Dam x Hubbard JA 57 Ki chickens during 6-10 weeks should contain 19% CP with 3.2 kcal ME/g. Exp. 3 was conducted during 11-15 WOA. The total of 1,700 heads of 1 day old chicks with 50% male and 50% female were fed with diet containing 19% CP, 3.2 kcal ME/g until 10 WOA. Then 1,260 heads of healthy chicks composed of 630 males and 630 females were used. Each sex was randomly allocated into 6 groups of 3 replicates containing 35 birds/rep. They were fed with diets containing either 17 or 15% CP. Each CP level contained 3 ME levels, i.c. 3.2 vs. 2.9 vs. 2.6 kcal/g. The result revealed that no significant interaction between CP and ME on all parameters. The 17% CP diets gave significantly better BWG, ADG, FCR, FCG and the intake of CP, methionine, lysine than the 15% CP diets. Decreasing dietary ME from 3.2 to 2.9 or 2.6 kcal/g gave higher BWG, ADG and FI but worse FCR and FCG, while the 2.9 kcal ME/g diet gave the highest BWG and ADG (P<0.05) than the other 2 ME levels. Neither CP nor ME had significant effect on carcass percentage and carcass composition, except the gizzard and abdominal fat which were higher (P<0.05) with the decreasing level of ME. Male had significantly higher BWG, ADG, FI, and all nutrient intake, including carcass percentage drumsticks, liver and gizzard but lower breast meat and abdominal fat than female. Sex had no significant effect on FCR, FCG, mortality rate, the percentage of thighs and wings (P>0.05). The optimum ration for this crossbred native chicken during 11-15 WOA should contain 17% CP with 2.9 kcal ME/g due to the best production performance and low feed cost.