Intramuscular fat levels in sheep muscle during growth

2008 ◽  
Vol 48 (7) ◽  
pp. 904 ◽  
Author(s):  
M. J. McPhee ◽  
D. L. Hopkins ◽  
D. W. Pethick

A 5 × 4 factorial experiment was designed in which lambs representing five genotypes were slaughtered at four ages (110, 236, 412 and 662 days of age). The genotypes represented were Poll Dorsetgrowth × Border Leicester Merino, Poll Dorsetgrowth × Merino, Poll Dorsetmuscling × Merino, Merino × Merino and Border Leicester × Merino. Both sexes (ewes and wethers) were represented for each genotype and slaughter age combination. In total, 595 animals were slaughtered and the carcass composition and intramuscular fat were measured. Carcass composition [fat, ash and protein (lean)] was determined by dual energy X-ray absorptiometry, with the intramuscular fat percentage determined using near-infrared spectroscopy following removal and weighing of the entire longissimus thoracis et lumborum (LL) muscle. Analysis revealed that the proportion of intramusular fat in the loin relative to total carcass fat decreases as animals mature, thus indicating that intramusular fat deposition occurs early in the maturation of sheep. Furthermore, as animals became heavier and older the accretion rate of intramuscular fat in the LL muscle slowed down. Both genotype (P < 0.05) and sex (P < 0.001) were found to impact on this pattern, with Border Leicester × Merino animals exhibiting the largest increase in intramuscular fat proportion in the LL muscle (4.92 and 5.50% at 22 months of age for ewes and wethers, respectively). The Poll Dorsetgrowth × Border Leicester Merino animals were found to have the greatest absolute levels of intramuscular fat in the whole LL muscle (80.95 and 97.60 g at maturity for ewes and wethers, respectively). The amount of intramuscular fat significantly increased as the sheep became older and fatter; however, these differences were quantitatively small. As such, finishing prime lambs to high levels of total carcass fatness would have little effect on any eating quality benefits associated with increased intramuscular fat proportion.

2009 ◽  
Vol 2009 ◽  
pp. 117-117
Author(s):  
E A Navajas ◽  
R I Richardson ◽  
C A Glasbey ◽  
N Prieto ◽  
D W Ross ◽  
...  

X-ray computed tomography (CT) scanning makes use of the different rates at which the tissues attenuate X-rays depending on their densities. CT muscle density (MD) is the average pixel value for this tissue in the CT images and is related to real density of the tissue, which depends on its chemical composition. One of the components determining muscle density is intramuscular fat (IMF). Studies in sheep have shown that MD, measured in vivo, was phenotypically and genetically correlated to IMF and to fatty acid (FA) composition in Scottish Blackface lambs (Karamichou et al. 2006). Intramuscular fat and FA are important traits to measure due to their association with the nutritional value and eating quality of meat. A novel automatic image analysis for spiral CT scans (SCTS) of beef primal cuts allows very accurate estimations of primal cut and carcass composition with R2 of 0.90 to 0.99 (Navajas et al., 2008). The aim of this study was to investigate the associations of MD of beef primal cuts with IMF and FA profile in Aberdeen Angus (AA) and Limousin (LIM) cattle, based on the CT thresholds estimated as part of the development of the image analysis described by Navajas et al. (2008).


Sports ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 85 ◽  
Author(s):  
Logan Posthumus ◽  
Campbell Macgregor ◽  
Paul Winwood ◽  
Katrina Darry ◽  
Matthew Driller ◽  
...  

This study explored the physical and fitness characteristics of elite professional rugby union players and examined the relationships between these characteristics within forwards and backs. Thirty-nine elite professional rugby union players from the New Zealand Super Rugby Championship participated in this study. Body composition was measured using dual-energy X-ray absorptiometry alongside anthropometrics. Fitness characteristics included various strength, power, speed, and aerobic fitness measures. Forwards were significantly (p ≤ 0.01) taller and heavier than backs, and possessed greater lean mass, fat mass, fat percentage, bone mass, and skinfolds. Forwards demonstrated greater strength and absolute power measures than backs (p = 0.02), but were slower and possessed less aerobic fitness (p ≤ 0.01). Skinfolds demonstrated very large correlations with relative power (r = −0.84) and speed (r = 0.75) measures within forwards, while backs demonstrated large correlations between skinfolds and aerobic fitness (r = −0.54). Fat mass and fat percentage demonstrated very large correlations with speed (r = 0.71) and aerobic fitness (r = −0.70) measures within forwards. Skinfolds, fat mass, and fat percentage relate strongly to key fitness characteristics required for elite professional rugby union performance. Individual and positional monitoring is important due to the clear differences between positions.


1999 ◽  
Vol 87 (3) ◽  
pp. 1114-1122 ◽  
Author(s):  
Willa C. Fornetti ◽  
James M. Pivarnik ◽  
Jeanne M. Foley ◽  
Justus J. Fiechtner

The purpose of this investigation was to determine the reliability and validity of bioelectrical impedance (BIA) and near-infrared interactance (NIR) for estimating body composition in female athletes. Dual-energy X-ray absorptiometry was used as the criterion measure for fat-free mass (FFM). Studies were performed in 132 athletes [age = 20.4 ± 1.5 (SD) yr]. Intraclass reliabilities (repeat and single trial) were 0.987–0.997 for BIA (resistance and reactance) and 0.957–0.980 for NIR (optical densities). Validity of BIA and NIR was assessed by double cross-validation. Because correlations were high ( r = 0.969–0.983) and prediction errors low, a single equation was developed by using all 132 subjects for both BIA and NIR. Also, an equation was developed for all subjects by using height and weight only. Results from dual-energy X-ray absorptiometry analysis showed FFM = 49.5 ± 6.0 kg, which corresponded to %body fat (%BF) of 20.4 ± 3.1%. BIA predicted FFM at 49.4 ± 5.9 kg ( r = 0.981, SEE = 1.1), and NIR prediction was 49.5 ± 5.8 kg ( r = 0.975, SEE = 1.2). Height and weight alone predicted FFM at 49.4 ± 5.7 kg ( r = 0.961, SEE = 1.6). When converted to %BF, prediction errors were ∼1.8% for BIA and NIR and 2.9% for height and weight. Results showed BIA and NIR to be extremely reliable and valid techniques for estimating body composition in college-age female athletes.


Meat Science ◽  
2016 ◽  
Vol 112 ◽  
pp. 185 ◽  
Author(s):  
O.P. Soladoye ◽  
Ó. López Campos ◽  
J.L. Aalhus ◽  
N. Prieto ◽  
C. Gariépy ◽  
...  

1997 ◽  
Vol 29 (Supplement) ◽  
pp. 53
Author(s):  
J. Eckerson ◽  
G. Moore ◽  
J. Stout ◽  
D. Noonan ◽  
D. Cullen ◽  
...  

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