This study was performed to estimate genetic parameters using 32,370 verification record materials and 32,370 pedigree materials for recent 8 years on 8 pedigrees out of Korea native chicken pure breed groups which have been established and preserved as pure breeds since 1994 by Poultry Research Complex in National Institute of Animal Science, and to utilize the results of this study as basic materials to compose parent pedigrees to improve Korea native chicken pure breeds and develop new additive species through a comparative study on cross combination utilizing Korea native chicken pure breeds. For distributed analysis on environmental factors and genetic parameter estimation, an analysis was performed by setting year of incubation and pedigree factors as fixed effects. To estimate genetic parameters, considering the same effects, polymorphic animal model was used. To estimate phenotype and genetic change trend, a regression analysis was made on least square mean value and mean breeding value of traits of the pedigrees to year of incubation.
On the other hand, in the comparative study on the production capabilities of cross combination by fixing Korea native chicken (native stock, Jaerae) and indigenous species as paternal line and maternal line respectively, we tried to establish recruit and breeding program to improve genetic capabilities of Korea native chicken pure breed group by comparing capabilities of chickens in development period and egg?laying period according to cross combination, and to utilize resulting materials to establish appropriate cross combination to develop additive species in the future.
The summary of major results of this study is as follows.
1. General mean value of the first egg?laying age (in days) of Korea native pure breed chickens was 152.35, 145.34, and 143.01 days in Jaerae (native stock) Heuksaek, Jeokgalsaek, and Hawnggalsaek respectively. In indigenous species, leghorn F, K, Cornish brown and black, Rhode island C breed showed 141.85, 143.35, 158.75, 152.79, and 147.72 days respectively.
2. General mean value of number of eggs that 270 days old Korea native pure breed chickens lay was 71.50, 85.32, and 90.63 in Jaerae Heuksaek, Jeokgalsaek, and Hawnggalsaek respectively In indigenous species, leghorn F and K, Cornish brown and black, and Rhode island C showed 98.91, 98.80, 61.31, 70.31, and 93.86 respectively.
3. In general mean value of the first egg?laying age and egg weight, mean egg weight that 150 days old Korea native pure breed chickens lay was 37.5, 35.96, and 34.32g in native stock Heuksaek, Jeokgalsaek, and Hawnggalsaek respectively and the mean value of egg weight that 270 days old chickens lay was 55.01, 53.74, and 52.04g respectively. Indigenous species leghorn F and K, Cornish brown and black, and Rhode island C showed 38.28, 35.56, 40.84, 37.95, and 38.62g in 150 days old chickens and 36.13, 61.03, 61.18, 59.379, and 60.04g in 270 days old chickens.
4. General mean value of weight of 150 days old Korea native pure breed chickens was 1,784.58, 1,682.09, 1,673.36g in native stock Heuksaek, Jeokgalsaek, and Hawnggalsaek respectively, and mean value of weight of 270 days old Korea native pure breed chickens was 2,143.64, 1,935.72, and 1,935.62g respectively. Indigenous species leghorn F and K, Cornish brown and black, and Rhode island C breed showed 1,422.11, 1,369.99, 3,144.05, 3,915.22 1,611.11g when they were 150 days old and 1,632.45, 1,575.02, 3,894.85, 3,711.03, and 2,037.22g when they were 270 days old.
5. In data structure analysis for environment effect analysis on traits of Korea native pure breed chickens, most of traits were found to satisfy normality. In significance test, they showed high significance (P<0.05) in the effects of year of incubation and pedigree that this study set.
6. In the trend of phenotype, the first egg?laying age got reduced as generations passed and in the egg weight on the first egg?laying day, native stock showed continuing reduction although there was some fluctuation, while indigenous breeds showed overall reduction or steady maintenance although there was somewhat severe fluctuation. In weight, native stock showed constant increase, while indigenous species showed overall increase although the width of increase was smaller than native stock.
7. In the estimation of heritability, the first egg?laying age of native stock Heuksaek, Jeokgalsaek, and Hawnggalsaek the scope of heritability of 0.39～0.44 (medium), egg weight in the first egg laying day 0.16 and 0.17, weight at 150 days 0.49～0.63, weight at 270 days 0.63～0.72, egg weight laid by 270?day?old chickens 0.57～0.64, and the number of eggs laid by 270?day?old chickens 0.24～0.35. On the other hand, indigenous species leghorn K and F, Cornish black and brown, and Rhode island breed showed heritability range of 0.24～0.46 in the first egg?laying age, 0.14～0.21 and 0.49～0.62 in egg weight at the first egg?laying age and 270 days respectively, 0.38～0.53 and 0.41～0.65 in weight at 150 days and 270 days, and 0.21～0.37 in the number of eggs at 270 days.
8. In correlation between phenotype and heredity, the correlation of phenotype and genotype between the number of eggs at the first egg?laying age and at 270 days was ?0.56 and ?0.39, the correlation of phenotype and genotype between the number of eggs and egg weight at the first egg?laying and 270 days, weight at 150 days and 270 days was ?0.17, ?0.30, ?0.29, ?0.30 and ?0.18, ?0.02, 0.05, 0.05 respectively.
9. Next, we looked into the trend of genetic changes in each breed against test traits according to estimated breeding value. It was confirmed that the first egg?laying age showed the same pattern of changes according to increasing and decreasing pattern of the number of eggs when the trend of genetic changes against the first egg?laying age which had strong negative correlation with the number of eggs laid by 270?day?old native stock chickens. Additionally, although there was some difference in the width, overall genetic change trend was same in egg weight laid by 150?day?old chickens and 270?day?old chickens, and weight of 150?day?old chickens and 270?day?old chickens in native stock black, red brown, and yellowish brown breeds.
10. To get basic material to nurture a chicken raised for breeding that can be used for practical native stock production, we investigated the capabilities of a chicken raised for breeding by cross breeding between Korea native stock and indigenous species. In survival rate (%)cross combination C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) showed the highest value as over 90% during the development period and B (Korean Rhode Island Red?C × Korean Black Cornish) crossbreed showed the lowest value as 73～78% (P<0.05).
11. In the weight of 4?week?old chickens, A (Korean Rhode Island Red?C × Korean Brown Cornish) crossbreed was the highest, D (Heuksaek Jaerae?jong × Korean Black Cornish) crossbreed was the lowest (P<0.05). In the weight of 8?week?old chickens, D (Heuksaek Jaerae?jong × Korean Black Cornish) crossbreed was the lowest (P<0.05). In the weight gain by week B (Korean Rhode Island Red?C × Korean Black Cornish) and C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) crossbreed showed higher value than A (Korean Rhode Island Red?C × Korean Brown Cornish) and D (Heuksaek Jaerae?jong × Korean Black Cornish) 0 to 4 week old (P<0.05). There was no significant difference among crossbreed in 0 week, 8 seeeks, 12 weeks and 16 weeks (p>0.05).
12. In feed consumption according to age of the week, there was no significant difference among cross combination throughout the development period (p>0.05), and in feed demand rate D (Heuksaek Jaerae?jong × Korean Black Cornish) crossbred showed the highest demands at 0～4 age of the week. To summarize the results of this study, it is considered effective to nurture B (Korean Rhode Island Red?C × Korean Black Cornish) and C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) that showed excellent growth capabilities in early period as a maternal line of meat amount type chicken.
13. Although there was no significant difference in the first egg?laying age, egg weight laid at the first egg?laying day, and weight in first egg?laying day among crossbreeds (P>0.05), cross combination B (Korean Rhode Island Red?C × Korean Black Cornish) showed the earliest in the first egg?laying age as 128.8 days cross combination A (Korean Rhode Island Red?C × Korean Brown Cornish) showed the latest as 134.5 days. In the egg weight at the time of the first egg?laying day, cross combination C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) was the lowest as 39.1g, and in the weight at the time of the first egg?laying, cross combination C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) showed the heaviest as 2,741g.
14. When looking into the weight during egg?laying period by the age of the week, cross combination D showed significantly lower weight than other crossbreeds at 24 weeks, 32 weeks, 40 weeks and 60 weeks (P<0.05). Although there was no significant difference in other age slots (p>0.05), in overall there was tendency for crossbreeds between native stock and indigenous species to show lower weight than crossbreeds between indigenous species. In average feed consumption during egg?laying period according to age of the week, crossbreeds between indigenous species such as cross combination A (Korean Rhode Island Red?C × Korean Brown Cornish) and cross combination B (Korean Rhode Island Red?C × Korean Black Cornish) showed much consumption.
15. Although there was no difference among crossbreed in mean weight of egg according to age in 48～52 week, and 60～64 week old chickens (P>0.05), cross combination A (Korean Rhode Island Red?C × Korean Brown Cornish) showed the highest mean egg weight in other age slots (P<0.05). In mean egg weight throughout egg?laying period, cross combination A (Korean Rhode Island Red?C × Korean Brown Cornish) showed higher value than cross combination C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) and cross combination D (Heuksaek Jaerae?jong × Korean Black Cornish) (P<0.05). On the other hand, feed demands were higher in cross combination C(Jeokgalsaek Jaerae?jong × Korean Brown Cornish) and cross combination D (Heuksaek Jaerae?jong × Korean Black Cornish) than cross combination A(Korean Rhode Island Red?C × Korean Brown Cornish) and cross combination B(Korean Rhode Island Red?C × Korean Black Cornish) (P<0.05).
16. In egg production index by age of the week, cross combination A (Korean Rhode Island Red?C × Korean Brown Cornish) and cross combination B (Korean Rhode Island Red?C × Korean Black Cornish) showed higher results than cross combination C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) and cross combination D (Heuksaek Jaerae?jong × Korean Black Cornish) (P<0.05). On the other hand, egg production was decreasing before 36 weeks of age in all cross combinations, and cross combination A (Korean Rhode Island Red?C × Korean Brown Cornish) and cross combination B (Korean Rhode Island Red?C × Korean Black Cornish) showed higher egg production than cross combination C (Jeokgalsaek Jaerae?jong × Korean Brown Cornish) and cross combination D (Heuksaek Jaerae?jong × Korean Black Cornish) (P<0.05),
17. In the review of capabilities of a chicken raised for breeding resulted from crossbreeding between Korea native stock and indigenous species in the development period to get basic materals to nurture a chicken raised for breeding that can be used for practical egg?laying native stock, the weight at the 4th week was the lowest in cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) (P<0.05), and at the 8th week cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) showed the highest weight (P<0.05). In the weight at the 12th week and 16th week, cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) and cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) were heavier than cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) (P<0.05).
18. In the amount of increase in weight according to age of the week, cross combination C(Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D(Korean Rhode Island Red?C × Baeksaek Jaerae?jong) showed lower value than cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) and cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) (P<0.05), and at the amount of increase in weight at the age of 0～20 weeks, cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) showed relatively higher increase than other crossbreeds. (P<0.05).
19. In feed consumption according to age of the week, cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) showed less demand at the age of 0～12 weeks, 0～16 weeks and 0～20 weeks than other cross combinations (P<0.05). Cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) showed the highest feed demand rate according to age of the week (P<0.05).
20. In age of the day when the chicken starts laying eggs steadily to produce egg?laying native stock chicken breed, crossbreed B showed the latest first egg?laying age out of 4 crossbreeds (p<0.05), and egg weight and weight of chicken at the time of first steadily laying egg period, cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) was the heaviest (P<0.05). In the comparison of average weight by age of the week between crossbreeds, cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) were significantly lower than cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) and cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) in all age slots (P<0.05).
21. In average feed consumption, cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) that showed the heaviest weight showed the biggest consumption (p<0.05), and cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) showed relatively higher consumption than cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) (P<0.05). According to age of the week, all crossbreeds showed reduced intake after the 50th week and increased intake in 68～72 weeks slot.
22. In the average egg weight according to age of the week, there was no difference among crossbreeds up to 50th week, and after 50th week cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) showed the highest value in average egg weight. Cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) showed the lowest value (P<0.05). In feed demand rate, cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) and cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) showed higher demands than cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) (P<0.05).
23. In the comparison of egg production index among crossbreeds, there was no significant difference among crossbreeds in egg production index according to age of the week (p>0.05). In the tendency of egg production index of crossbreeds according to age of the week, cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) showed the highest egg production index, while cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong) showed the lowest egg production index. There was no significant difference in age egg production index up to 72 weeks in aforementioned 4 crossbreeds showing 238.0, 232.7, 257.1 and 253.8 respectively. (p>0.05).
24. In egg production, there was no significant difference among crossbreeds in all age slots (p>0.05). In the tendency of egg production among crossbreeds, cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) showed high tendency of egg production in each age slot, and all crossbreeds showed constant reduction in egg production after 38 weeks of age. Egg production in post egg?laying period (68～72 weeks), 4 cross combination showed 61.0%, 51.8%, 55.6% and 55.0% respectively. Although cross combination A (Korean Rhode Island Red?C × Hwanggalsaek Jaerae?jong) showed higher tendency than cross combination B (Korean Rhode Island Red?C × Heuksaek Jaerae?jong), cross combination C (Korean Rhode Island Red?C × Hoegalsaek Jaerae?jong) and cross combination D (Korean Rhode Island Red?C × Baeksaek Jaerae?jong) showed higher tendency than those two aforementioned combinations in whole period of egg?laying period.