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Title: PROTEIN, FAT, AND BONE MINERAL DEPOSITION RATES IN GROWING PIGS (BIRTH TO 90 KG) OF DIFFERENT RYR1 GENOTYPES STUDIED BY DUAL ENERGY X-RAY ABSORPTIOMETRY

Author
item SCHOLZ, A. - UNIVERSITY MUNICH
item Mitchell, Alva

Submitted to: Energy Metabolism of Farm Animals Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/23/2003
Publication Date: 9/1/2003
Citation: Scholz, A.M., Mitchell, A.D. 2003. Protein, fat, and bone mineral deposition rates in growing pigs (birth to 90 kg) of different RyR1 genotypes studied by dual energy x-ray absorptiometry. In: Progress in Research on Energy and Protein Metabolism: (W.B. Souffrant and C.C. Metges, Eds.). EAAP Scientific Series v.109:543-548.

Interpretive Summary: Improvement of lean or protein growth and efficiency are two of the main objectives in pig breeding. The application of constant maintenance requirements, efficiency ratios for protein and fat deposition, and growth rates may lead to model assumptions/ feeding strategies, which would not exactly meet the changing requirements of pigs of different genotypes during growth. Therefore, this experiment was aimed at the study of protein, fat, and bone mineral deposition and efficiency in pigs of different "model" genotypes covering growth and body composition changes from birth to 90 kg live body weight using dual energy x-ray absorptiometry as a non-invasive measuring tool. The results indicate that the amount of daily protein and fat deposition depends on the body composition/ genetic background while observing nearly identical total tissue deposition rates for the three genotypes over time. At the end of the growth period studied (60-90 kg live body weight), the leanest genotype had a faster decreasing rate of protein deposition than the less lean pigs due to a slower total tissue growth caused by a comparatively lower (appetite) feed intake.

Technical Abstract: A growth study was performed from birth to 90 kg live body weight (BW) using dual energy x-ray absorptiometry (DXA) as a non-invasive tool to measure the deposition rates of main body components protein (lean), fat, and bone mineral in different ryanodine receptor 1 (RyR1) "model" genotypes (NNà "fat", Nn à intermediate, nn à lean). The pigs were scanned at 10, 30, 60, and 90 kg BW. Fat and bone mineral measurements were used directly, while the lean mass was used to calculate protein mass (protein deposition rate -- Pd) using a device specific regression equation based on chemical reference data. Pd increases steadily up to about 50 kg body weight (Pdmax ~140 g/d for nn) and then gradually declines. The amount of daily protein and fat deposition depends on the body composition/ genetic background (metabolic situation) while observing nearly identical total tissue deposition rates for the three genotypes over time. At the end of the growth period studied (60-90 kg BW), the leanest genotype (nn) has a faster decreasing Pd than the less lean ("intermediate" - Nn, "fat" - NN) pigs due to a slower total tissue growth caused by a comparatively lower (appetite) feed intake (nn=2.14, Nn=2.5, NN=2.46 kg/d). The linear plateau model for Pd related to energy intake holds in tendency only for the "intermediate" genotype.