NUCLEIC-ACID CONCENTRATIONS AND ORNITHINE DECARBOXYLASE ACTIVITY IN TISSUES FROM 3 LINES OF TURKEYS

Developmental patterns in turkeys of tissue ornithine decarboxylase (O DC) activity and nucleic acid concentrations were studied in a randomb red control (RBC2), in a subline of RBC2 selected for increased 16-wk BW (F), and in a commercial sire line (C). Lines F and C were similar in BW, but Line C had greater breast weight than Line F. Lines F and C were heavier and had greater breast weights than the RBC2 population. Tissue ODC activity reached its highest level on Day 2 posthatch, dec lined rapidly through 13 d of age, and remained relatively low through 144 d of age. The ODC activity of liver tissue was greater than that of either breast or leg muscle. Line C had greater tissue ODC activity at 2 and 8 d of age than the RBC2 population, but Line F was not diff erent from C or RBC2. There were no line differences for ODC activity at the other ages tested, resulting in a age by line interaction. The DNA content of muscle tissue was greatest at hatch and declined to bas eline values by 55 d of age. The DNA content of breast muscle was high er than for leg muscle at hatch, but this pattern was reversed followi ng Day 8. Muscle tissue from Lines F and C had a lower DNA content tha n that of the RBC2 population. Although the RNA content of muscle tiss ue was similar across lines, the RNA content of breast muscle was grea ter than for leg muscle during the early posthatch period just prior t o the onset of rapid growth in this tissue. Results of the present exp eriment demonstrate changes in muscle functional cellularity during th e growth phase in association with genetic increases in BW, but not br east muscle development. In contrast, tissue ODC activity was increase d in association with genetic increases in breast muscle development, but not BW.