Genotype and age effects on sheep meat production. 4. Carcass composition predicted by dual energy X-ray absorptiometry

2007 ◽  
Vol 47 (10) ◽  
pp. 1172 ◽  
Author(s):  
E. N. Ponnampalam ◽  
D. L. Hopkins ◽  
F. R. Dunshea ◽  
D. W. Pethick ◽  
K. L. Butler ◽  
...  

This study compares the carcass composition of different genotypes of Australian sheep slaughtered at four ages (110, 236, 412 and 662 days of age, or 4, 8, 14 and 22 months of age). The genotypes used were Poll Dorsetgrowth × Border Leicester Merino (PDg × BLM), Poll Dorsetgrowth × Merino (PDg × M), Poll Dorsetmuscling × Merino (PDm × M), Merino × Merino (M × M) and Border Leicester × Merino (BL × M). Approximately 150 mixed sex animals were slaughtered at each age and the right sides (half carcass) were scanned by dual energy X-ray absorptiometry (DXA) for chemical lean, fat and bone mineral percentages of the carcass. Carcass lean percentage decreased (P < 0.001) across sire groups from Merino to Poll Dorset to Border Leicester at each age, while fatness increased (P < 0.001) in the opposite direction. With age, the magnitude of difference between genotypes for fatness became greater. There was a marked increase (P < 0.01) in ash mineral percentages in M × M and PDg × M genotypes relative to other genotypes in the 14- and 22-month groups. There were no differences (P > 0.1) between PDg × M and PDm × M in either chemical lean or fat percentages at any age but ash mineral percentage was higher in the PDg × M genotype at older ages (P < 0.05). This in turn led to differences in chemical lean : ash mineral content at later ages between PDg × M and PDm × M. Wethers had higher chemical lean (P < 0.05) and lower fat (P < 0.05) percentages in the carcass than ewes at all ages but ash mineral and chemical lean : ash mineral content did not differ between sexes. It was clear that the level of chemical lean or fat or ash mineral composition reached by some genotypes at one age was equivalent to that reached by other genotypes at the next measurement age. Those genotypes that reach a specification at younger ages will be more productive for meat production. Purebred Merino genetics will always be less productive in terms of carcass weight and muscle related productive traits (loin weight, semitendinosus muscle weight, eye muscle area) than BL and PD genetics, but the relative productivity of PD and BL genetics will depend on the traits used in the specification [see also Ponnampalam EN, Hopkins DL, Butler KL, Dunshea FR, Warner RD (2007) Genotype and age effects on sheep meat production. 2. Carcass quality traits. Australian Journal of Experimental Agriculure 47, 1147–1154]. The results suggest that selection for muscling had a greater impact on reducing ash mineral content associated with bone mineral mass than on increasing lean mass in the carcass.

1992 ◽  
Vol 81 (12) ◽  
pp. 953-958 ◽  
Author(s):  
Bernard L Salle ◽  
Pierre Braillon ◽  
Francis H Glorieux ◽  
Jacques Brunet ◽  
Eduardo Cavero ◽  
...  

2019 ◽  
Vol 316 (1) ◽  
pp. R59-R67
Author(s):  
Tamara Hew-Butler ◽  
Kailyn Angelakos ◽  
Joshua Szczepanski

The purpose of this study was to assess relationships between plasma sodium concentration ([Na+]) and bone mineral content (BMC) after an acute sodium load plus treadmill walking and then quantify the amount of sodium the dual energy X-ray absorptiometry (DXA) scan could detect. The primary study was a single-blind randomized control crossover trial under two conditions: ingestion of six flour tablets (placebo trial) or six 1-g NaCl tablets (salt intervention trial). The tablets were ingested after baseline blood and urine collection followed immediately by the DXA scan. After 60 min of rest, a 45-min treadmill walk was conducted. Immediately postexercise, blood and urine were collected and the DXA scan was repeated. Main outcomes included changes (∆: post minus pre) in plasma [Na+] and BMC. Additionally, six 1-g NaCl tablets were superimposed over a DXA spine phantom for separate quantification of sodium as BMC. Fourteen subjects completed the primary study. Two-way repeated measures ANOVA tests revealed significant interaction ( F = 13.06; P = 0.0007), condition ( F = 21.88; P < 0.001), and time ( F = 6.51; P = 0.014) effects in plasma [Na+]. A significant condition ( F = 6.46; P = 0.014) effect was also noted in urine [Na+]. Total body BMC∆ was negatively correlated with plasma [Na+]∆ ( r = −0.43; P = 0.02) and urine [Na+]∆ ( r = −0.47; P = 0.01). Total body BMC∆ in the salt intervention trial [−5.5 (27) g] closely approximated the amount of NaCl ingested and subsequently absorbed into the bloodstream. The DXA scan quantified 67% of NaCl tablets as BMC in spine phantom analyses. Total body BMC∆ was negatively related to plasma and urine [Na+]∆ after treadmill walking. Reductions in total body BMC closely approximated the amount of NaCl ingested (~6 g). The DXA scan quantified NaCl as BMC.


1993 ◽  
Vol 26 (11) ◽  
pp. 1691-1696
Author(s):  
Yoshio Nomura ◽  
Hiroaki Mizoguchi ◽  
Masayuki Nakagawa ◽  
Nobuyoshi Nasu ◽  
Tsutomu Nishida ◽  
...  

2009 ◽  
Vol 11 (2) ◽  
pp. 275-285 ◽  
Author(s):  
Christina D. Economos ◽  
Miriam E. Nelson ◽  
Maria A. Fiatarone ◽  
Gerard E. Dallal ◽  
Steven B. Heymsfield ◽  
...  

2008 ◽  
Vol 104 (4) ◽  
pp. 1116-1120 ◽  
Author(s):  
Yoshihisa Umemura ◽  
Seigo Nagasawa ◽  
Naota Sogo ◽  
Akiko Honda

We investigated whether the effects of jump training on bone are preserved after a detraining period in female normal and estrogen-deficient rats. Forty-four 11-wk-old Wistar rats were divided into the following four groups: sham sedentary ( n = 12), sham exercised ( n = 11), ovariectomized sedentary ( n = 10), and ovariectomized exercised ( n = 11). An 8-wk exercise period was introduced in which the rats in the exercised groups were jumped 10 times/day, 5 days/wk. This was followed by 24 wk of detraining. At the end of the exercise period, the jump training significantly increased the bone mineral content of the tibia ( P < 0.001), measured by dual-energy X-ray absorptiometry. After the detraining period, the bone mineral content ( P < 0.01), strength ( P < 0.001), and cross-sectional widths ( P < 0.001) of the tibia in the exercised groups were still greater than in the sedentary groups, without significant surgery-exercise interactions, although bone stiffness in the fracture test ( P < 0.05) and bone area in the center-proximal region, as measured by dual-energy X-ray absorptiometry ( P < 0.05), showed significant surgery-exercise interactions. These findings suggest that the exercise effect on bone strength is preserved, accompanied by cross-sectional morphological changes, even under estrogen deficiency.


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