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Ponnampalam E.N.,Australian Sheep Industry Cooperative Research Center | Ponnampalam E.N.,Australian Department of Primary Industries and Fisheries | Warner R.D.,Australian Department of Primary Industries and Fisheries | Kitessa S.,CSIRO | And 4 more authors.
Animal Production Science | Year: 2010

Thirty 7-month-old crossbred lambs (Poll Dorset Border Leicester Merino) finished over 5 weeks on either low quality pasture or grain-with-hay on a farm in southern Victoria were assessed for carcass parameters, muscle fat composition and retail colour stability. Lambs on the grain diet had a mix of barley grain (80%) and lentils (20%) at 800 g/head.day (air-dry basis ∼ad libitum) with cape weed (Arctotheca calendula) hay available at all times. Lambs under grazing had predominantly rye grass (Lolium perenne) and barley grass (Hordeum leporinum) available ad libitum. Carcass weight tended to be higher (P ≤ 0.14) in grain-fed lambs than in grass-fed lambs, but fatness indicated by GR (total muscle + fat tissue thickness at 11 cm from midline) did not differ between feeding systems. Fatty acid composition was determined in the loin from the forequarter (M. longissimus thoracis) and lumbar (M. longissimus lumborum) regions and from the leg region (M. semimembranosus). This showed that grain-finished lamb had higher muscle fat (P 0.001) and omega-6 fatty acid (P 0.001) content. Alpha-linolenic acid, eicosapentaenoic acid (EPA) or total omega-3 fat did not differ (P 0.05) between feeding groups. Saturated fatty acids were greater (P 0.01) in both loin sampling sites than the leg. The levels of EPA, docosahexaenoic acid and docosapentaenoic acid were lower (P 0.01) in the forequarter (9%) or lumbar (11%) sites than the leg sampling site. The distribution pattern of fatty acids across the three sampling sites did not differ between feed types. Retail colour stability determined over 4 days of display (only performed in muscle from the lumbar site), evaluated by the redness (HunterLab a*-value) and metmyoglobin formation (reflectance ratio at 630:580-nm wavelengths) was superior for grass-fed lamb compared with short-term grain-finished lamb. The results demonstrate that the health claimable omega-3 fat mainly EPA or total omega-3 fat content in lamb was not altered by short-term grain finishing compared with lamb finished under pasture grazing conditions. © 2010 CSIRO.

Hopkins D.L.,Australian Cooperative Research | Toohey E.S.,Australian Department of Primary Industries and Fisheries | Warner R.D.,Center for Sheep Meat Development | Kerr M.J.,Industry and Investment NSW Primary Industries | Van De Ven R.,Orange Agricultural Institute
Animal Production Science | Year: 2010

The tenderness of 160 samples of m. longissimus thoracis et lumborum (LL) from 40 sheep carcasses was measured at two laboratories, 80 samples per laboratory, with two ageing times (0 and 5 days). The samples were all cooked from frozen and then measured on the same type of machine, a Lloyd Texture analyser with a WarnerBratzler-type shearing blade attached to give a shear force value for each sample. Shear force results were natural log-transformed and the analysis showed that there was a significant (P < 0.001) effect of ageing on shear force and a significant (P = 0.01) difference between the laboratories. Thus, on equivalent samples, Laboratory B produced shear force results 0.78 times those for Laboratory A. There was no significant (P > 0.05) effect of ageing on cooking loss, but there was a significant (P < 0.05) difference between the laboratories. On equivalent samples, Laboratory B produced lower cooking loss results (expressed as a percentage), on average by 3.1%, than did Laboratory A. When cooking loss was included in the model for shear force, it was significant (P < 0.001), and its inclusion reduced the significance (P = 0.04) of the difference between laboratories. Thus, part of the differences between the two laboratories for shear force could be explained by the difference in the cooking loss at the two laboratories. As cooking loss increased, shear force increased. © 2010 CSIRO.

Khliji S.,Center for Sheep Meat Development | Khliji S.,University of Catania | van de Ven R.,Orange Agricultural Institute | Lamb T.A.,Center for Sheep Meat Development | And 3 more authors.
Meat Science | Year: 2010

Given the lack of data that relates consumer acceptance of lamb colour to instrument measures a study was undertaken to establish the acceptability thresholds for fresh and displayed meat. Consumers (n = 541) were asked to score 20 samples of lamb loin (m. longissimus thoracis et lumborum; LL) on an ordinal scale of 1 (very acceptable) to 5 (very unacceptable). A sample was considered acceptable by a consumer if it scored three or less. Ten samples were used for testing consumer response to fresh colour and 10 to test consumer response to colour during display of up to 4 days. The colour of fresh meat was measured using a Minolta chromameter with a closed cone and a Hunter Lab Miniscan was used for measuring meat on display. For fresh meat when the a* (redness) and L* (lightness) values are equal to or exceed 9.5 and 34, respectively, on average consumers will consider the meat colour acceptable. However a* and L* values must be much higher (14.5 and 44, respectively) to have 95% confidence that a randomly selected consumer will consider a sample acceptable. For aged meat, when the wavelength ratio (630/580 nm) and the a* values are equal to or greater than 3.3 and 14.8, respectively, on average consumers will consider the meat acceptable. These thresholds need to be increased to 6.8 for ratio (630/580 nm) and 21.7 for a* to be 95% confident that a randomly selected consumer will consider a sample acceptable. Crown Copyright © 2010.

Refshauge G.,Cooperative Research Center | Refshauge G.,Center for Sheep Meat Development | Hatcher S.,Cooperative Research Center | Hatcher S.,Orange Agricultural Institute | And 5 more authors.
Animal Production Science | Year: 2010

Concerns exist that selection for increased clean fleece weight (CFW) is expected to reduce body fatness. Such an effect is likely to impact on reproduction; however, all previous studies have examined non-reproductive yearlings or hoggets. The present study, using adult reproductive dams examined the impact of phenotype [based on high or low phenotypic CFW and bodyweight (BWT) performance], stocking rate (high or low) and litter size on body composition and wool traits. High CFW dams were heavier (P < 0.01) with lower fat depth (P < 0.01) and muscle depth (P < 0.05). The high CFW twin-weaning dams had a lower fat score from lamb marking to pre-joining (P < 0.05), but tended to replete fat reserves faster (P < 0.1) between weaning and pre-joining. At these times of repletion these animals grew longer wool staples (P < 0.05). High BWT ewes had reduced staple length (P < 0.01), and when adjusted for maternal liveweight also reduced fat depth (P < 0.001) and muscle depth (P < 0.05). We conclude that the CFW phenotype impacts on fat reserves but that management of dams in groups according to their CFW performance is not warranted. © 2010 CSIRO.

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