In vivo estimation of carcass meat by ultrasound in ram lambs slaughtered at an average live weight of 37 kg

Abstract

Ultrasonic measurements of fat thickness and m. longissimus depth 25 and 50 mm lateral to the mid line at the last rib and 100 mm caudally to the last rib were made, before slaughter, on 273 ram lambs using two probes: the Scanogram and Krautkramer. The lambs were from three strains: a meat-type sire strain and two fecund dam strains. They weighed on average 37·3 kg at scanning, (range 29·0 to 51·3 kg), well within the weight range over which Canada Al-grade lambs are marketed in Canada. Their carcasses contained on average 437 g trimmed boneless meat per kg (s.d. pooled within strain = 24·1 g/kg).The precision with which the ultrasonic measurements combined with live weight at scanning predicted trimmed boneless meat (weight and proportion) was examined. Fat thickness measurements had no predictive value (P > 0·05). The residual standard deviations for the prediction of trimmed boneless meat in the half carcass (weight and proportion) from weight at scanning were 0·29 kg and 21·5 kg, respectively; the addition of the m. longissimus depth measurement reduced the residual standard deviations by 0·02 kg and 1·1 g/kg, respectively. The weight of trimmed boneless meat was predicted with more precision than the proportion of trimmed boneless meat. Strain, location of measurement site or type of instrument did not change the precision of prediction.It is concluded that prediction of trimmed boneless meat in young ram lambs based on live animal ultrasonic measurements made with the Scanogram or Krautkramer lacks the level of precision necessary for practical application.

The use of seemingly unrelated regression to predict the carcass composition of lambs

“…The HCW had a low and statistically insignificant correlation with the C12 measurement (r = 0.13) and a moderate positive correlation (r = 0.52) with E2. These results are in agreement with the low variability of the LMP observed by Silva (2001) and Cadavez (2009), and this small variation in the carcasses' LMP was pointed out as the main constraint to prediction models with high determination coefficient (Cadavez, 2009;Fortin & Sherestha, 1986;Silva, 2001), since this statistic is highly influenced by the variation of the dependent variable (Chatterjee, Hadi, & Price, 2000).…”

Ultrasonic estimates of fat thickness and Longissimus dorsi muscle depth for predicting carcass composition of live Aragon lambs

“…For the experimental conditions in this study, the usefulness of ultrasonic fat depth measurements for estimating carcass composition appeared to be questionable. However, the data led to Thompson et al ( 1977)) Kempster ( 1981)) Fortin and Shrestha ( 1986) and Edwards et al ( 1989), the prediction of carcass composition of sheep using ultrasonic measurements is of limited application, and perhaps the use of another type of ultrasound machine and a different probe would determine lamb carcass composition more accurately.…”

The use of X-ray computer tomography for measuring the muscularity of live sheep

“…However, these correlations are likely to be an underestimate of the 'true' accuracy of the technique in most studies, and particularly in this study. That the shape of the LTL muscle can change post slaughter as a consequence of the carcass being hung, chilled and split is widely accepted (Fortin and Shrestha, 1986;Binnie et al, 1995). Some increase in area and depth likely result due to the effects of cold shortening of the muscle prior to the onset of rigor mortis.…”