Development of a Model to Predict Intramuscular Fat in Live Pigs Using Real-Time Ultrasound

Recent developments in real-time ultrasound technology offer producers an opportunity to estimate intramuscular fat in live pigs. Genetic improvement of intramuscular fat will continue as an emphasis in swine breeding programs and genetic progress in this important trait will be possible through implementation of this technology

Direct and Correlated Responses to Selection for Intramuscular Fat in Duroc Swine

At the present state of technology, intramuscular fat percentage can be accurately evaluated in live pigs and utilized in conjunction with sib carcass data for estimation of breeding values for intramuscular fat. Within the population under study, selection on resulting EBV has yielded a significant phenotypic change in all measures of IMF. Phenotypic gain in IMF established through selection in the current study resulted in IMF levels that may be useful for differentiation of sire lines for use in muscle quality-based niche markets. Results from this study illustrate that phenotypic improvement of IMF may correspond to an increase in objective tenderness, and shed light into the possible ramifications of this response in measures of carcass composition. Intramuscular fat may be used in swine breeding programs as an indicator of general product palatability; however, sensory characteristic improvements are likely to be slow when simultaneous improvement in other trait categories is also pursued

Genetic Parameter Estimates of Production, Meat Quality, and Sensory Traits in Duroc Swine

Heritability estimates detected for carcass composition, meat quality, and sensory measures indicate that improvement in these traits may be attained if adequate selection pressure is applied. Estimates obtained within the current population illustrate that substantial genetic relationships exist between many economically relevant traits. Genetic parameters estimated after 6 generations of selection for intramuscular fat indicate that the use of ultrasound technology may provide a non-invasive method for genetic improvement of IMF and other meat and eating quality components. However, genetic improvement programs aimed at meat quality improvement should be aware of possible adverse effects on carcass leanness, muscling, and loin color

Comparison of Serial Ultrasonic Measurements of Loin Muscle Area, Backfat, and Intramuscular Fat Percentage Between Pigs Sired by Boars from Two Different Time Periods

Results of this study demonstrate that significant progress toward the enhancement of carcass composition has been realized within the Duroc breed since the mid 1980’s; however, this improvement has been at the expense of meat quality traits such as intramuscular fat. This report also suggests that the deposition rates and growth patters of loin muscle area, tenth-rib backfat, and intramuscular fat percentage have not been significantly affected by long-term selection for increased carcass leanness

Relationship Between Backfat Depth and its Individual Layers and Intramuscular Fat Percentage in Swine

Results show the correlations between IMF and different measures of total fat thickness are of similar magnitude, regardless of the measure being a single measure of total subcutaneous fat or a sum of the individual layers. Results also show that the correlation between the inner and outer backfat layers is less than the correlation between the middle layer and the inner and outer layers

Lifetime Reproductive Traits in Landrace, Yorkshire and Crossbred Sows

Selection for more robustness could improve sow longevity. The problem is that sow longevity is truly expressed in crossbred sows in commercial herds but selection is performed among purebred animals in nucleus herds. The present study investigated sow longevity traits on both levels to determine whether the use of commercial performance can facilitate added genetic progress in nucleus animals. Heritability estimates were estimated from 0.00 to 0.16 for Landrace, Yorkshire and crossbred F1sows. Preliminary results indicate that it could be useful to implement data from crossbred sows in breeding evaluations to improve selection accuracy for sow longevity

Evaluating Growth, Loin Muscle Area, and Backfat Accretion During Summer and Winter for Finishing Pigs in Bedded Hoop and Confinement Buildings

Growth and development of finishing pigs in bedded hoop and confinement buildings during summer and winter was evaluated using serial ultrasound measurements of backfat (BF) thickness, loin muscle (LM) area, and serial weighing. A summer trial (April through August 2000) and a winter trial (October 2000 through February 2001) were conducted. Forty-eight pigs from the hoop building and eight pigs from each of the six pens in the confinement building were randomly selected and weighed; ultrasound images were recorded every 14 d during the last 56 d of the finishing phase. Backfat accretion rates were greater for summer hoop pigs (SH) than summer confinement pigs (SC) at 80 kg to 90 (P \u3c 0.05), but did not differ at 95 to 115 kg. In winter, BF accretion rates did not differ from 80 to 105 kg, but winter hoop pigs (WH) had less BF accretion than winter confinement pigs (WC) at 110 kg and 115 kg (P \u3c 0.05). Loin muscle accretion rates did not differ at 80 and 85 kg or from 100 to 115 kg, but were less for SH than SC at 90 kg and at 95 kg (P \u3c 0.001). WH had greater LM accretion rates than WC at 80 kg to 115 (P \u3c 0.05). Bodyweight gain (BWG) did not differ between SH and SC from 80 to 95 kg and was greater for SH at 100 kg to 115 kg (P \u3c 0.05). Bodyweight gain did not differ for WH and WC pigs from 100 to 115 kg, but was less for WH than WC at 80 kg to 95 kg (P \u3c 0.05). These results indicate that performance of finishing pigs is dependent on the thermal environment, and that hoop-reared pigs (particularly in winter) may compensate for a lag in performance early in the finishing period with greater accretion rates of LM and BW and lower accretion rates of BF later in the finishing period. Although overall pig performance in hoop and confinement buildings is similar, some differences in accretion rates for bodyweight, backfat, and loin muscle area occurred during the finishing period. These differences are probably due to seasonal variation in the thermal environment. Performance of pigs reared in hoop buildings may be compromised early in the finishing period by their inability to overcome the difference between temperature and thermoneutrality. However, it appears that hoop-reared pigs compensated for earlier lags in performance by increased BW gain and LM accretion, along with less BF deposition compared to pigs in confinement at the same BW. This study provides some evidence to justify feeding pigs in hoops to heavier weights. Research studying accretion rates of pigs at a wider range of bodyweights will be needed to better understand the effects of environment and building type on pig performance