Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/26/2002
Publication Date: 5/20/2002
Citation: BURNHAM, M.R., PEEBLES, E.D., BRANTON, S.L., MAURICE, D.V., GERARD, P.D. EFFECTS OF F-STRAIN MYCOPLASMA GALLISEPTICUM INOCULATION AT TWELVE WEEKS OF AGE ON EGG YOLK COMPOSITION IN COMMERCIAL EGG LAYING HENS. JOURNAL OF POULTRY SCIENCE. 2003. V. 82. P. 577-584. Interpretive Summary: Mycoplasma gallisepticum (MG) has long been associated with decreases in egg production. These egg production losses are estimated at 16 eggs/hen per laying cycle which is about 45 weeks in duration and results in an overall cost to the table egg industry of about $120 million annually. Depending upon the age of the chicken when it is infected with MG, egg production losses can be minimized and even eliminated under certain circumstances. Since the organism is very particular about what nutrients it needs to survive and one of the major nutrients it requires is cholesterol which in turn is found in eggs, this research was conducted to determine what differences occur in cholesterol, lipids, fatty acids, and other components of eggs from chickens when they were infected with MG as compared with non-infected hens. Numerous differences were found to occur in several components of eggs and these data suggest that alterations in egg production in commercial layer chickens in response to MG infection are associated with changes in the composition of the egg yolk.
Technical Abstract: In two trials, the effects of F-strain Mycoplasma gallisepticum (FMG) on the content of egg yolks from commercial Single Combed White Leghorn laying hens were investigated over a production cycle. Ten hens were assigned to each of eight (Trial 1) or sixteen (Trial 2) negative pressure fiberglass biological isolation units. Birds in half or the total units served as sham-inoculated controls and those in the other half were inoculated with FMG at 12 w of age. Eggs were collected and yolks were harvested at various times during the pre-peak, peak, and post-peak periods of both trials for constituent analysis. Yolk constituents analyzed in theses trials included moisture, total lipids, cholesterol, triglycerides, phospholipids, and fatty acids. In both trails, total yolk lipid at 22 wk of age was significantly decreased in birds inoculated with FMG. In Trail 1, yolk cholesterol at 28 wk was significantly decreased in FMG-inoculated birds. Yolk linoleic acid in Trial 1, and yolk stearic and arachidonic acids in Trial 2, were significantly increased in FMG-inoculated birds compared to FMG-free birds. In Trial 2, yolk myristic, palmitoleic, and oleic acid percentages were significantly decreased in FMG-inoculated birds compared with FMG-free birds. These data suggest that alterations in egg production in commercial layers in response to an FMG infection at 12 wk of age, as noted in a previous report, are associated with changes in yolk composition.