The Effects Of Perch Availability In Osteoporotic Chickens

Osteoporosis in cage laying hens is a significant disease affecting nearly 30 percent of hens at the end of lay (71 weeks). The two primary causes may be a the result of mechanical unloading leading to decrease bone density coupled with extremely high bone turnover rate that is necessary for releasing calcium for eggshell production. Few studies have examined the molecular mechanisms behind bone remodeling in hens at any stage of development and adulthood. In my first study, I examined bone specific transcripts related to bone formation and remodeling using prior to sexual maturity (12 weeks) and senescence hens (5 year old). Utilizing quantitative reverse transcriptase polymerase chain reaction (QRT-PCR) we were able to measure relative quantity of transcription productions within the carpometaphalange, tibia and femur. My first study examined COL2A1, SOX9, PTH-LH, PTH1R, PTH3R, RANKL and OPG. We did not observe any significant difference among treatment groups or bone. In my second study, I focused on examining the same bone specific transcripts using 71 weeks hens. In this study, we examined the effects of mechanical loading. By adding a perch to traditional cage we were able to induce mechanical loading to determine if access to a perch alters the molecular markers related to bone remodeling. This study consisted of four treatment groups. In the first treatment group, hens were housed in traditional cages throughout the entire lifespan, while in the second treatment group the chickens had access to a perch throughout 71 weeks. In the third treatment group, hens were exposed to perch to just prior sexual maturity but switched to a traditional cage for the remainder. In the fourth treatment group, hens started in traditional cages but switched to a perch cage just prior to sexual maturity. Our QRT-PCR results indicated there was no significant difference among all treatment groups with the exception of COL2A1 in the femur being significantly expressed in comparison to the phalange and tibia throughout all treatment groups. This study provides insight in the molecular mechanism of bone remodeling in hens. Future studies should encompass more transcripts to further examine what differences exist between the hens and the mammalian model