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GENETICS |

* Department of Animal Science, Iowa State University, Ames 50011; and
Department of Animal Sciences, Purdue University, West Lafayette, IN 47907
1 Corresponding author: moodyd{at}iastate.edu
Osteoporosis is a serious problem for the laying hen industry with economic, production, and welfare consequences. Transforming growth factor-ß2 (TGFß2) has been implicated as an important factor in coupling bone resorption and formation in bone remodeling. The current study was designed to determine if TGFß2 was associated with variation in bone mineralization in chickens, using 2 complementary experimental approaches. First, an intronic single nucleotide polymorphism (SNP) present in TGFß2 was investigated in an F2 population to determine its association with bone, growth, and egg traits of importance to the layer and broiler industries. The TGFß2 SNP was significantly associated (P < 0.05) with bone mineral density and content. However, these associations became nonsignificant when BW was included as a covariate in analyses. The TGFß2 SNP was also significantly associated (P < 0.05) with BW from 1 to 6 wk of age and egg production from 46 to 55 wk of age. To further explore the relationship between TGFß2 and bone strength, bone marrow TGFß2 mRNA abundance was compared between broiler and layer chickens at 15, 35, and 60 wk of age. Bone and egg traits were measured along with mRNA abundance at each age and found to differ significantly between lines. The TGFß2 mRNA abundance was approximately 4-fold greater in broiler compared with layer hens at 15 wk of age but was similar between lines at later ages. Thus, even though the TGFß2 SNP will likely not be an effective marker for improving bone strength independently of changes in BW, further research is warranted to investigate the relationship of TGFß2 mRNA abundance to bone strength in laying hens.
Key Words: chicken gene expression osteoporosis single nucleotide polymorphism transforming growth factor-ß2
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