Showing papers by "John Mitchell Thompson published in 2009"

Genetics of meat quality and carcass traits and the impact of tenderstretching in two tropical beef genotypes

Abstract: Meat quality and carcass traits were measured for 2180 feedlot finished Brahman (BRAH) and Tropical Composite (TCOMP) steers to investigate genetic and non-genetic influences on shear force, and other meat quality traits. Genetic and phenotypic correlations were estimated between carcass and meat quality traits, and with live animal measurements collected in steers from weaning to feedlot exit, and their heifer half-sibs up to their first mating, which were managed in Australia’s tropical or subtropical environments. Left sides of carcasses were tenderstretched (hung by the aitch-bone) while right sides were conventionally hung (by the Achilles tendon). Tenderstretching reduced mean shear force by 1.04 kg, and phenotypic variance by 77% of that observed in conventionally hung sides. Genotype differences existed for carcass traits, with TCOMP carcasses significantly heavier, fatter, with greater eye muscle area, and lower retail beef yield than BRAH. TCOMP had lower shear force, and higher percent intramuscular fat. Meat quality and carcass traits were moderately heritable, with estimates for shear force and compression of 0.33 and 0.19 for BRAH and 0.32 and 0.20 for TCOMP respectively. In both genotypes, estimates of heritability for carcass traits (carcass weight, P8 and rib fat depths, eye muscle area and retail beef yield) were consistently moderate to high (0.21 to 0.56). Shear force and compression were genetically correlated with percent intramuscular fat (r g = –0.26 and –0.57, respectively), and meat colour (r g = –0.41 and –0.68, respectively). For TCOMP, lower shear force was genetically related to decreased carcass P8 fat depth (r g = 0.51). For BRAH steers and heifers measured at pasture, fatness traits and growth rates were genetically correlated with shear force, although the magnitude of these relationships varied with time of measurement. Net feed intake was significantly genetically correlated with carcass rib fat depth (r g = 0.49), eye muscle area (r g = –0.42) and retail beef yield (r g = –0.61). These results demonstrate that selection to improve production and carcass traits can impact meat quality traits in tropically adapted cattle, and that genotype specific evaluations will be necessary to accommodate different genetic relationships between meat quality, carcass and live animal traits.

A new system of refillable and uniquely identifiable diffusion tubes for dynamically generating VOC and SVOC standard atmospheres at ppm and ppb concentrations for calibration of field and laboratory measurements

Abstract: Calibration of trace analyses for volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) is an important but sometimes neglected aspect of environmental monitoring. Static methods using mixtures of VOCs in compressed air or nitrogen suffer from uncertain adsorptive losses on the gas cylinder wall and are not well suited for SVOCs. Dynamic methods enable generation of standards when needed, using permeation or diffusion tubes in thermostatted ovens through which a carrier gas flows whose flow-rate is user-controlled. We describe a new system of refillable diffusion tubes engraved with individual serial numbers (for quality systems traceability) that users can easily calibrate gravimetrically in a few weeks, compared with several months for gravimetric calibration of permeation tubes. These devices may be useful for calibrating ppm and ppb measurements of VOCs and SVOCs. Using appropriately low temperatures and an inert carrier gas, it may also be possible to generate standards for many labile and oxygen sensitive compounds.

Brahman and Brahman crossbred cattle grown on pasture and in feedlots in subtropical and temperate Australia. 1. Carcass quality

Abstract: Brahmans are known to have poorer carcass quality relative to Bos taurus breeds and crossbreds under temperate environments; however, little is known of their performance in subtropical environments The Cooperative Research Centre for Cattle and Beef Industry (Meat Quality) initiated a crossbred progeny test experiment to compare straightbred Brahmans with Brahman crossbreds finished on pasture and grain, in subtropical and temperate environments, to carcass quality specifications of Australian domestic and export markets Brahman, Belmont Red, Santa Gertrudis, Angus, Hereford, Shorthorn, Charolais and Limousin sires were mated to Brahman females in subtropical Queensland over 3 years to produce 1750 progeny At a common age at slaughter, Charolais crossbreds had the highest hot carcass weight (CWT) but were not significantly heavier than Limousin or British crossbred progeny At common carcass weights, breeds within breed type (British, Continental, tropically adapted) performed similarly British and Santa Gertrudis crossbreds had the fattest carcasses and lowest yields British and Belmont Red crossbreds had the highest intramuscular fat percentage (IMF) Continental crossbreds had the highest retail beef yield (RBY), kilograms of retail primals (RTPM) and percent retail primals (pcRTPM) and leanest carcasses Brahmans had the lowest CWT, intermediate subcutaneous fat cover, high yields and low IMF Animals finished in the subtropics on pasture were significantly older, leaner and had higher RBY, RTPM and pcRTPM than subtropical feedlot-finished contemporaries Temperate feedlot animals had significantly more IMF, less subcutaneous fat at the P8 site and slightly lower yields than subtropical feedlot contemporaries, indicating possible effects of postweaning growth path on fat distribution Belmont Red crossbreds demonstrated the advantages of adaptation with the highest IMF in both subtropical finishing regimes, while Angus progeny had the highest IMF in the temperate feedlot environment and highest IMF overall when analysed across finishing regimes Significant interactions were mainly the result of scale effects rather than breed re-ranking for carcass traits across markets and finishing regimes Therefore, breeds that performed well for certain carcass traits in subtropical environments performed consistently for those traits in temperate environments relative to other sire breeds, regardless of market endpoint or finishing nutrition

The aggregate economic benefits to 2007/08 from the adoption of meat standards Australia

Abstract: Meat and Livestock Australia funded a major R&D program in the mid 1990s to investigate the relationships between observable beef characteristics, cooking methods and consumer appreciation of beef palatability. Out of this R&D grew the Meat Standards Australia (MSA) voluntary meat grading system which was aimed primarily at providing an accurate prediction of beef eating quality for the domestic market. The MSA system commenced operations in 1999/2000. A survey of retailers and wholesalers based on prices for MSA graded beef (3 star or better) versus ungraded beef was used to quantify the gross benefits associated with using the MSA system. Over the period 2004/05 to 2007/08, beef consumers across Australia were prepared to pay around $0.32/kg extra for MSA branded beef on a carcass weight equivalent

Brahman and Brahman crossbred cattle grown on pasture and in feedlots in subtropical and temperate Australia. 2. Meat quality and palatability

Abstract: Market demand for a reliable supply of beef of consistently high eating quality led the Cooperative Research Centre for Cattle and Beef Industry (Meat Quality) to initiate a crossbreeding progeny test program to quantify objective and sensory meat quality differences between straightbred and first-cross Brahman cattle Brahman, Belmont Red, Santa Gertrudis, Angus, Hereford, Shorthorn, Charolais and Limousin sires were mated to Brahman females over 3 years to produce 1346 steers and heifers in subtropical northern Australia Calves were assigned within sire by age and weight to one of three market endpoints (domestic, Korean or Japanese), one of two finishing environments (subtropical or temperate) and one of two finishing diets (pasture or feedlot) Average carcass weights were 227, 288 and 327 kg for domestic, Korean and Japanese markets respectively Only steers were finished for the Japanese market The effects of sire breed, finishing regime, market endpoint and sex on sensory meat quality of four attributes score (CMQ4), ossification score and Warner-Bratzler shear force (SF), instron compression (IC), ultimate pH and percent cooking loss (CL) on the M longissimus thoracis et lumborum (LT) and M semitendinosus (ST) were determined Straightbred Brahmans had the highest SFLT (539 ± 007; P 465) There was little difference between crossbred progeny for most meat quality traits All feedlot-finished animals were slaughtered at domestic, Korean and Japanese market weights by 24 months of age, with minimal differences in objective measures of meat quality between markets The IC measures for all sire breeds were below 22 kg, indicating connective tissue toughness was not an important market consideration in feedlot-finished animals slaughtered by 24 months of age Pasture finishing adversely affected all meat quality traits (P < 0001) except CLST, with Korean and Japanese market animals having unacceptably tough SF, IC and CMQ4 measures This was attributed to their older age at slaughter (31 and 36 months respectively), resulting from their seasonally interrupted growth path While domestic animals slaughtered at 25 months of age off pasture had unacceptably high SF and IC, CMQ4 was acceptable Subtropical feedlot animals had slightly more desirable (ns) SF and IC relative to temperate feedlot animals, whereas temperate feedlot animals had higher CMQ4 (P < 0001) Genotype × environment interactions were not important

The cost of non-compliance to beef market specifications

Abstract: Strategic sourcing of cattle that are more likely to meet market specification is a critical challenge for buyers purchasing animals for feedlot finishing Missing target specifications has the potential to result in a large discount in carcass value Costs associated with carcass weight and external fat depth that is out of specification impact on both the ability of suppliers to meet customer requirements and levels of productivity or slaughter rates that are nearer to the processor’s cost-minimising level of production This analysis used a subset of Australian beef industry feedlot data from two long-fed feedlots to assess both the costs and causes of carcasses out-of-specification The economic value associated with products that are out-of-specification can be illustrated by the Taguchi Quadratic Loss Function, carcass specifications, and industry grid prices At the nominated carcass weight specification (300kg - 400kg) in the short-fed export market, there were 28 per cent outside of specification, while in the long-fed export market (380kg - 450kg), 29 per cent were outside specification A P8 fat depth specification of 10mm-26mm showed 16 per cent outside of specification in the short-fed market At the nominated marbling score specification (3+) in the long-fed market, 70 per cent were outside of

Benefits of genetic superiority in residual feed intake in a large commercial feedlot.

Abstract: Cooperative Research Centre for Beef Genetic Technologies 1 NSW Department of Primary Industries, Beef Industry Centre, Armidale, NSW, 2351 2 Division of Animal Science, University of New England, Armidale, NSW, 2351 3 NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Camden, NSW, 2570 4 NSW Department of Primary Industries, Tamworth Agricultural Institute, Tamworth, NSW, 2340 5 NSW Department of Primary Industries, Agricultural Research Institute, Trangie, NSW, 2823

Selection for muscling reduces muscle response to adrenaline

Abstract: Carcass lean meat yield is a key profit driver within the sheep and beef industries, and is improved by selection for muscling. This selection causes muscle hypertrophy which is associated with greater proportions of fast-gylcolytic type IIX myofibres in both cattle and sheep (Wegner el al., 2000; Greenwood el aI., 2007). Muscle tissue that is high in type IIX myofibres will also have increased gylcolytic and gylcogenolytic capacity (Wegner el al, 2000), which is likely to result us a greater potential for stress/adrenaline induced muscle glycogen depletion. This has great relevance to industry, as low muscle glycogen at slaughter will result in high ultimate pH (>5.7) carcases leading to dark firm dry (DFD) meat. However, in contradiction to this theory Martin el al. (2004) found more muscle glycogen in sheep selected for muscling. This was most evident when energy intake was high, implicating greater insulin sensitivity which may counteract the hypothesised greater adrenaline response. Therefore a link between selection for muscling and response to stress/adrenaline remains to be confirmed. In this study, we tested the hypothesis that selection for muscling will increase the muscle response to adrenaline.

Fat distribution in Angus steers is related to residual feed intake estimated breeding value

Abstract: A.R. Egarr, W.S. Pitchford, M.J. Bottema, R.M. Herd, J.P. Siddell, J.M. Thompson and C.D.K. Bottema