Estimation of Genetic Variations and Selection of Superior Lines from Diallel Crosses in Layer Chicken

산란계종의 잡종강세 이용을 위한 유전학적 기초연구와 우량교배조합 선발에 관한 연구

The subject of this study was to obtain some genetic information for developing superior layer chickens. Heterosis and combining ability effects were estimated with 5,759 progenies of full diallel crosses of 6 strains in White Leghorn. Fertility, hatchability, brooder-house viability, rearing- house viability, laying-house viability, age at 1st egg laying, body weight at 1st egg laying, average egg weight, hen-day egg production, hen-housed egg production, and feed conversion were investigated and analyzed into heterosis effect, general combining ability, specific combining ability and reciprocal effect by Grilling's model I. The results obtained were summarized as follows; 1. The general performance of each traits was 94.76% in fertility, 74.05% in hatchability, 97.47% in brooder-house viability, 99.72% in rearing-house viability, 93.81% in laying-house viability, 150 day in the age at 1st egg laying, 1,505g in the body weight at 1st egg laying, 60.08g in average egg weight, 77.11% in hen-day egg production, 269.8 eggs in hen-housed egg Production, and 2.44 in feed conversion. 2. The heterosis effects were estimated to -0.66%, 9.58%, 0.26%, 1.83%, -3.87%, 3.63%, 0.96%, 4.23%, 6.4%, and -0.8%, in fertility, hatchability, brooder-house viability, laying-house viability, the age at 1st egg laying, the body weight at 1st egg laying, average egg weight, hen-day egg Production, hen-housed egg production and feed conversion, respectively. 3. The results obtained from analysis of combining ability were as follows ; 1) Estimates of general combining ability, specific combining ability and reciprocal effects were not high in fertility. It was considered that fertility was mainly affected by environmental factors. In the hatchability, the general combining ability was more important than specific combining ability and reciprocal effects, and the superior strains were K and V which the additive genetic effects were very high. 2) In the brooder-house viability and laying-house viability, specific combining ability and reciprocal effects appeared to be important and the combinations of K${\times}$A and A${\times}$K were very superior. 3) In the feed conversion and average egg weight, general combining ability was more important compared with specific combining ability and reciprocal effects. On the basis of combining ability the superior strains were F, K and B in feed conversion, F and B in the average egg weight. 4) General combining ability, specific combining ability and reciprocal effects were important in the age at 1st egg laying and the combination of V ${\times}$F, F${\times}$K and B${\times}$F were very useful on the basis of these effects. In the body weight at 1st egg laying, general combining ability was more important than specific combining ability and reciprocal effects, relatively. The K, F and E strains were recommended to develop the light strain in the body weight at 1st egg laying. 5) General combining ability, specific combining ability and reciprocal effects were important in the hen-day egg production and hen-housed egg production. The combinations of F${\times}$K, A${\times}$K, and K${\times}$A were proper for developing these traits. 4. In general, high general combining ability effects were estimated for hatchability, body weight at 1st egg laying, average egg weight, hen-day egg production, hen-housed egg production, and feed conversion and high specific combining ability effects for brooder-house viability, laying house viability, age at 1st egg laying, hen-day egg production and hen-housed egg production, and high reciprocal effects for the age at 1st egg laying.

본 연구에서는 산란종계 육종개발에 필요한 기초자료를 얻기 위하여 산란종계 6계통을 양면교잡시켜 생산된 후대 3,759수를 가지고 교잡에 의한 잡종강세효과와 결합능력을 추정하였다. 공시계는 국립종축원 대전지원에서 보유하고 있는 White LKeghorn종 6계통에서 생산된 36개 조합의 양면교잡종을 이용하여 1984년 5월 11일부터 1985년 9월23일까지 500일간 수행하였으며, 수정율, 부화율, 육추율, 유성율, 성계생존율, 초산일령, 초산시 체중, 평규란중, 생존계산란율, 산란지수 및 사료요구율 등을 조사하였다. 조사된 각 형질에 대한 기록을 분석하여 교잡에 의한 잡종강세효과, 일반결합능력, 특수결합능력, 상반교잡효과 등을 추정하였다. 분석방법은 Griffing(1956)의 Model I 모형을 이용하여 추정하였다. 본 연구에서 얻어진 결과를 요약하면 다음과 같다. 1. 조사된 형질의 일반능력은 수정율이 94.76%, 부화율이 74.05%, 육추율이 97.47%, 육성율이 99.72%, 생존율이 93.81%, 초산일령이 150일, 초산시체량이 1,505g, 평균란중이 60.08g, 생존계산란율이 77.11%, 산란지수가 269.8개, 사료요구율이 2.44로 나타났다. 2. 잡종강세의 크기는 수정율에서 -1.66%로 부의 방향으로 나타났으며 부화율에서 9.58%, 육추율에서 0.26%, 생존율에서 1.83%, 초산일령에서 -3.87%, 초산시체중에서 3.63%, 평균란중에서 0.96, 산란율에서 4.23%, 산란지수에서 6.4%, 그리고 사료요구율에서 -0.85%로 나타나 수정율과 체중을 제외한 모든 형질에서 바람직한 개량방향으로 잡종강세효과를 보여 주었으며, 비교적 유전력이 낮은 부화율, 사란능력에서는 잡종강세효과가 컸고, 유전력이 비교적 높은 란중은 잡종강세효과가 적었다. 3. 결합능력의 분석에서 얻어진 결과는 다음과 같다. 1)수정율 일반결합능력, 특수결합능력 및 상반교잡효과는 중요하지 않은 것으로 나타났으며, 수정율은 유전적 요인보다는 환경적인 요인에 의해 영향을 많이 받는 것으로 나타났다. 부화율에서는 일반결합능력이 큰 비중을 차지하였으며 특히 K와 V계통의 상가적 유전효과가 크게 추정되었다. 2) 사료요구율과 평균란중은 일반결합능력이 특히 중요하였으며 특수결합능력과 상반교잡효과도 중요하게 나타났다. 사료요구율은 F, K, B 계통에서 우수하였으며, 란중은 F, B 계통이 우수하게 나타났다. 4) 초산일령은 일반결합능력, 특수결합능력 및 상반교잡효과가 모두 중요하게 나타났으며, V$\times$E, F$\times$K, B$\times$F의 교배조합이 우수하였고, 초산시체중은 일반결합능력이 특히 중요하게 나타났으며 특수결합능력과 상반교잡효과도 중요하게 나타났다. 초산시체중을 가벼운 쪽으로 개량하고자 할 때 K, F, E 계통이 우수하였다. 5) 산란율과 산란지수는 일반결합능력, 특수결합능력, 상반교잡효과가 모두 중요하였으며, F$\times$K, $A\times$K, $K\times$A 조합에서 우수하게 나타났다. 4. 일반적으로 일반결합능력이 중요하게 나타난 형질은 부화율, 초산시체중, 평균란중, 산란율, 산란지수, 사료요구율이었고 특수결합능력이 중요하게 나타난 형질은 육추율, 성계생존율, 초산일령, 산란율, 산란지수였으며, 상반교잡효과가 중요하였던 형질은 초산일령이었다.