Tissue specific activity of pentose-phosphate oxidative enzymes during feeder lamb development /
| Main Author: | |
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| Other Authors: | , , , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1992.
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| Subjects: | |
| Online Access: | Link to OAKTrust copy |
| Abstract: | Rambouillet wether lambs (n = 60), similar in age and weight, were purchased from five ranches in West Texas and serially slaughtered at 0, 40, 80 and 120 d on feed to determine if pentose-phosphate oxidative enzymes were related to differential fat growth, and if the system could be used as selection criteria in livestock. Feed intake data were collected individually before slaughter to insure that intake did not affect enzyme activity. Rack dissection and carcass data were collected postmortem. Intramuscular fat (i.m.) content in the M. longissimus was determined with proximate analysis techniques. At slaughter, M. longissimus, subcutaneous fat (s.c.), intermuscular fat (INT) and kidney fat samples were collected and frozen in liquid-N2. Each sample was assayed for glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-PGDH) activity. Samples were isoelectrically focused (IEF) and electrophoresed with PAGE techniques to resolve tissue specific isoforms. Allometric analysis of rack fat growth indicated that s.c. fat was the earliest maturing, slowest growing depot, INT fat was the latest maturing, fastest growing depot and i.m. fat was intermediate (P < .05) when kidney fat was excluded. Kidney fat grew rapidly compared to carcass weight (P < .05). Enzyme assays suggested that G-6-PDH and 6-PGDH activities, and their ratios, closely followed differential growth patterns for fat (P < .05). Activities for both enzymes were low initially, increased by 40 d on feed, and subsequently declined. Tissue specificity was evident across time on feed endpoints (P < .05). Only one isoform was revealed for G-6-PDH using IEF, while three isoforms were found for 6-PGDH. No tissue specific bands were detected using IEF. Multiple and tissue specific forms of G-6-PDH were detected using PAGE, but bands did not reflect polymorphism. A unique G-6-PDH banding pattern was found for INT fat. Further research is necessary to ascertain with certainty if G-6-PDH polymorphisms exist for INT, and if selection against INT-specific forms would result in shifting patterns of differential fat growth. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Animal Science." |
| Physical Description: | x, 124 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |