Deposition rates and accretion patterns of intramuscular fat, loin muscle area, and backfat of Duroc pigs sired by boars from two time periods1

Abstract

A study was conducted to evaluate differences in performance and in carcass composition and tissue deposition rates between purebred Duroc pigs sired by boars currently available and those sired by boars from the mid-1980s. Two lines were developed by randomly allocating littermate and half-sib pairs of females to matings by current time period (CTP) or old time period (OTP) boars. Pigs from 2 replications were placed on test at a group mean BW of 63.5 kg. Serial ultrasonic measurements of the 10th-rib LM area (LMA), off-midline backfat (BF10), and intramuscular fat percentage (IMF) were collected every 2 wk in the first replication and used to assess deposition rate differences. Off-test ultrasonic LMA, BF10, and IMF measurements from a total of 557 pigs from 23 CTP sires and 232 pigs from 15 OTP sires across 2 replications and at a mean BW of 109 kg were evaluated. All available barrows and randomly selected gilts (n = 277) were sent to a commercial abattoir, and carcass measurements of 10th-rib backfat, last-rib backfat, last lumbar backfat, and LMA were collected. Analysis of serial backfat measurements revealed a linear relationship between back-fat and BW between 73 and 118 kg for pigs from both time periods. Pigs sired by OTP boars deposited more backfat (P < 0.05) at a faster rate than pigs sired by CTP boars over the entire test period. A curvilinear cumulative tissue deposition pattern was revealed for ultrasonically estimated LMA and IMF within both time periods. Significant linear and quadratic regression coefficient differences between lines indicated that pigs sired by CTP boars deposited more LMA and less IMF per kilogram of BW gain than pigs sired by OTP boars. Pigs sired by CTP boars had more LMA and less BF10 (P < 0.05), whereas pigs sired by OTP boars had more IMF (P = 0.04). Carcass evaluation revealed more (P < 0.01) carcass measurements of LMA and less (P < 0.05) carcass measurements of 10th-rib backfat, carcass measurements of last-rib backfat, and carcass measurements of last lumbar backfat for pigs sired by CTP boars. No difference (P > 0.05) between the time periods was found for ADG over the entire test period. Results from this study illustrate that significant progress in carcass composition has been realized within the Duroc breed since the mid-1980s. The long-term selection response in carcass leanness has also resulted in changes in deposition rates of correlated traits such as LMA and IMF.

Inhibition of adipogenic differentiation by myostatin is alleviated by arginine supplementation in porcine-muscle-derived mesenchymal stem cells

“…Animal growth performance has recently been improved by genetic selection, comfortable circumstances, and optimal nutrition, though these advances have been at the cost of meat quality [1]. IMF is one of the most important indexes of meat quality, and is positively correlated with factors such as shearing force, tenderness, and flavor.…”

“…Over the last few decades, the growth performance of domestic animals has been improved by genetic selection, comfortable circumstances, and optimal nutrition, which has led to poor meat quality [1]. Intramuscular fat (IMF) is one of the main factors affecting meat quality, and has attracted increasing attention in animal production [2,3].…”

Intermuscular and intramuscular adipose tissues: Bad vs. good adipose tissues

“…107 Long-term selection for decreased backfat in pigs was highly associated with decreased IM as well. 108 Selection for lean growth in sheep also significantly reduced IM. 109 A study of cattle selected for high growth indicated no change in IM lipid despite a significant increase in backfat accretion.…”

Association of the ADRB3, FABP3, LIPE, and LPL gene polymorphisms with pig intramuscular fat content and fatty acid composition

“…The Shanzhu pigs, one of the indigenous pigs in Jiangsu Province of China, are fatty pigs characterized by their good meat quality and a high level of IMF content. By contrast, the Duroc pig is an international breed mainly concentrated on the lean growth efficiency (Schwab et al 2007). Therefore, Shanzhu × Duroc crossbred pigs might possess good meat and fatness traits determined by IMF content and fatty acid composition.…”