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Estimation of genetic parameters for reproductive traits in connectedness groups of Duroc,Landrace and Yorkshire pigs in China |
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| Authors: | Suoyu Zhang Jinxin Zhang Babatunde Shittu Olasege Peipei Ma Xiaotian Qiu Hong Gao Changcun Wang Yuan Wang Qin Zhang Hongjie Yang Zhigang Wang Xiangdong Ding Yuchun Pan |
| Affiliation: | 1. School of Agriculture and Biology, Department of Animal Science, Shanghai Jiao Tong University, Shanghai, China National Animal Husbandry Service, Beijing, China;2. National Animal Husbandry Service, Beijing, China College of Animal Science and Technology, National Engineering Laboratory for Animal Breeding & Key Laboratory of Animal Genetics and Breeding of Ministry of Agriculture, China Agricultural University, Beijing, China;3. School of Agriculture and Biology, Department of Animal Science, Shanghai Jiao Tong University, Shanghai, China;4. National Animal Husbandry Service, Beijing, China;5. College of Animal Science and Technology, National Engineering Laboratory for Animal Breeding & Key Laboratory of Animal Genetics and Breeding of Ministry of Agriculture, China Agricultural University, Beijing, China |
| Abstract: | The objective of this study was to estimate group- and breed-specific genetic parameters for reproductive traits in Chinese Duroc, Landrace, and Yorkshire populations. Records for reproductive traits between April 1998 and December 2017 from 92 nucleus pig breeding farms, which were involved in the China Swine Genetic Improvement Program, were analysed. Due to weak genetic connectedness across all farms, connectedness groups consisting of related farms were used. Three, two and four connectedness groups for Duroc, Landrace and Yorkshire were firstly established according to the genetic connectedness rating among farms. For each connectedness group a five-trait animal model was implemented, and via restricted maximum likelihood procedure the genetic parameters were estimated for five reproductive traits i.e., total number born (TNB), number born alive (NBA), litter weight at farrowing (LWF), farrowing interval (FI) and age at first farrowing (AFF). The average of heritabilities among connectedness groups ranged from .01 (for FI in Yorkshire) to .30 (for AFF in Duroc). Estimates of repeatability for litter traits ranged from .14 to .20 and were consistent for each breed, and for FI, the estimates varied from .01 to .11 across breeds and groups. The estimated genetic correlations among litter traits (i.e., TNB, NBA and LWF) were all significantly high (>.56) and similar across breeds. Averaged genetic correlations over three breeds were −.25, −.27, −.18, −.04, −.10, −.02, and .28 for FI-TNB, FI-NBA, FI-LWF, AFF-TNB, AFF-NBA, AFF-LWF and FI-AFF, respectively. The standard errors of the estimates were all very low (<0.01) in most situations. Results from this study suggest that selection based on TNB which is currently used in dam line selection index can improve NBA and LWF simultaneously. However, care should be taken on FI and AFF as they are both greatly influenced by non-genetic factors such as management and measurement. |
| Keywords: | connectedness groups genetic parameters pigs reproductive traits |