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D W Pethick - One of the best experts on this subject based on the ideXlab platform.
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feed deprivation in Merino and terminal sired lambs 1 the metabolic response under resting conditions
Animal, 2019Co-Authors: S M Stewart, P Mcgilchrist, G E Gardner, D W PethickAbstract:The aim of this study was to examine the metabolic response to feed deprivation up to 48 h in low and high yielding lamb genotypes. It was hypothesised that Terminal sired lambs would have decreased plasma glucose and increased plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB) concentrations in response to feed deprivation compared to Merino sired lambs. In addition, it was hypothesised that the metabolic changes due to feed deprivation would also be greater in progeny of sires with breeding values for greater growth, muscling and leanness. Eighty nine lambs (45 ewes, 44 wethers) from Merino dams with Merino or Terminal sires with a range in Australian Sheep Breeding Values (ASBVs) for post-weaning weight (PWT), post-weaning eye muscle depth and post-weaning fat depth (PFAT) were used in this experiment. Blood samples were collected via jugular cannulas every 6 h from time 0 to 48 h of feed deprivation for the determination of plasma glucose, NEFA, BHOB and lactate concentration. From 12 to 48 h of feed deprivation plasma glucose concentration decreased (P < 0.05) by 25% from 4.04 ± 0.032 mmol/l to 3.04 ± 0.032 mmol/l. From 6 h NEFA concentration increased (P < 0.05) from 0.15 ± 0.021 mmol/l by almost 10-fold to 1.34 ± 0.021 mmol/l at 48 h of feed deprivation. Feed deprivation also influenced BHOB concentrations and from 12 to 48 h it increased (P < 0.05) from 0.15 ± 0.010 mmol/l to 0.52 ± 0.010 mmol/l. Merino sired lambs had a 8% greater reduction in glucose and 29% and 10% higher NEFA and BHOB response, respectively, compared to Terminal sired lambs (P < 0.05). In Merino sired lambs, increasing PWT was also associated with an increase in glucose and decline in NEFA and BHOB concentration (P < 0.05). In Terminal sired lambs, increasing PFAT was associated with an increase in glucose and decline in NEFA concentration (P < 0.05). Contrary to the hypothesis, Merino sired lambs showed the greatest metabolic response to fasting especially in regards to fat metabolism.
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effect of Merino sheep age on consumer sensory scores carcass and instrumental meat quality measurements
Animal Production Science, 2019Co-Authors: D W Pethick, G E Gardner, L PannierAbstract:Slower growing Merino sheep often miss the lamb category and become yearlings. Yet, they may still produce meat of acceptable eating quality, thus opening the opportunity to develop high quality yearling products. Consumer sensory differences (tenderness, overall liking, juiciness, liking of flavour and liking of odour) of grilled wet-aged (5 days) steaks from the M. longissimus lumborum (LL) and M. semimembranosus (SM) derived from wether lamb (n = 185; average age 355 days) and wether yearling (n = 206; average age 685 days) Merinos were tested. Additionally, the age effect on carcass and instrumental meat quality traits was analysed. Lambs were born in 2009 and 2010 at two research sites (Kirby, Katanning), and yearlings were born in 2009 at five research sites (Kirby, Cowra, Rutherglen, Struan, Katanning). On average within each muscle, yearlings had lower scores for all sensory attributes (P < 0.01) compared to lambs. Lambs versus yearlings born in the same year and reared at the same research site had greater sensory differences within the SM (P < 0.01), up to 10.0 eating quality scores more for tenderness. In contrast, the LL samples had almost no significant differences between the two age groups. A portion of the differences in overall liking and liking of flavour scores was explained by intramuscular fat. Yearlings were slightly heavier (P < 0.01) but leaner (P < 0.01), compared to lambs, and yearling meat colour was darker (P < 0.01). While the results generally supported the better eating quality of lamb, they demonstrated a very acceptable yearling LL eating quality, and showed the smaller impact of age on the LL muscle in Merinos. Hence, the development of a high quality yearling product for the LL muscle is possible.
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feed deprivation in Merino and terminal sired lambs 2 the metabolic response under pre slaughter conditions and impact on meat quality and carcass yield
Stewart S.M. McGilchrist P. Gardner G.E. ORCID: 0000-0001-7499-9986 and Pethick D.W. ORCID: 0000-0002-3255-7677 (2018) Feed deprivation in Merino and , 2018Co-Authors: S M Stewart, P Mcgilchrist, G E Gardner, D W PethickAbstract:Under current Australian industry pre-slaughter guidelines, lambs may be off feed for up to 48 h before slaughter. The purpose of this study was to examine what proportion of circulating metabolites at slaughter are due to stress and feed deprivation and if this response differs between Merino and Terminal genotypes. In addition the effect of feed deprivation on carcass weight and meat quality was examined. Jugular blood samples were collected from 88 Merino and Terminal sired lambs at rest and at slaughter following 24, 36 and 48 h of feed deprivation and plasma analysed for glucose, lactate, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB). From the same carcasses hot carcass weight (HCWT) were measured as well as a suite of meat quality traits measured such as M. longissimus lumborum (loin) and M. semitendinosus pH at 24 h postmortem. Loin samples were also analysed for intramuscular fat content and Warner-Bratzer Shear Force. Merino sired lambs had a higher NEFA response compared to Terminal sired lambs at slaughter after 24, 36 and 48 h of feed deprivation, with NEFA levels up to 35% higher than previously reported in the same animals at rest in animal house conditions, whereas BHOB response to feed deprivation was not affected by sire type (P>0.05) and similar to previously reported at rest. In addition to the metabolic effects, increasing feed deprivation from 36 h was associated with a 3% reduction in HCWT and dressing percentage as well as causing increased ultimate pH in the M. semitendinosus in Merino sired lambs. Findings from this study demonstrate that Merino and Terminal sired lambs differ in their metabolic response to feed deprivation under commercial slaughter conditions. In addition, commercial feed deprivation appears to have a negative effect on ultimate pH and carcass weight and warrants further investigation.
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sources of variation of health claimable long chain omega 3 fatty acids in meat from australian lamb slaughtered at similar weights
Meat Science, 2014Co-Authors: En Ponnampalam, D W Pethick, K L Butler, S I Mortimer, Kelly M Pearce, A J Ball, D L HopkinsAbstract:The sources of variation of health claimable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid, EPA + docosahexaenoic acid, DHA) in 2000 Australian lambs were investigated using 98 sires (Merino, maternal or terminal breeds) that were mated to about 5000 Merino or crossbred (Border Leicester × Merino) ewes. Pasture was supplemented with feedlot pellets, grains or hay as necessary, when the availability of quality green pasture was limited. Lambs were grown at 8 sites across Australia and when slaughtered the longissimus lumborum muscle was collected. Site and kills within sites were the major sources of variation for health claimable fatty acids. These environmental effects are likely to be driven by dietary background. The sire variance differed from about one twentieth to a half of the residual lamb within dam variation, depending on site and kill. This is the first comprehensive study to investigate on-farm sources of variation of long chain omega-3 polyunsaturated fatty acid content of lamb meat.
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effect of prolonged exposure to continuous heat and humidity similar to long haul live export voyages in Merino wethers
Animal Production Science, 2011Co-Authors: C Stockman, Anne L Barnes, Shane K Maloney, E G Taylor, M Mccarthy, D W PethickAbstract:This experiment investigated the physiological responses of Merino wethers (n = 12) to prolonged high heat and humidity similar to that experienced during long haul, live export voyages from Australia to the Middle East. Merino wethers were randomly assigned to individual pens in rooms with a controlled environment, and exposed to gradually increasing temperatures, and two exposures of 3–4 days of sustained high heat and humidity, up to a maximum of 31°C wet bulb temperature (37°C dry bulb and 67% relative humidity). There was 1 day at thermoneutral temperatures separating the heat exposures. The core temperatures and respiratory rates of Merino wethers increased during both heat exposures, with open-mouthed panting observed during both exposures. Plasma partial pressure carbon dioxide (pCO2) and bicarbonate concentration (HCO3–) decreased, and plasma pH increased during the second heat exposure. Both pCO2 and HCO3– returned to normal immediately following the heat exposures. Feed intake was maintained during the heat exposures. There were no large alterations in blood electrolyte concentrations attributable to the effects of the heat. The results show that Merino wethers experienced significant physiological changes during exposure to prolonged and continuous high heat and humidity, but maintained most aspects of homeostasis despite being hyperthermic and recovered quickly when conditions returned to thermoneutral.
Hulya Yalcintan - One of the best experts on this subject based on the ideXlab platform.
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carcass measurements and meat quality of turkish Merino ramlic kivircik chios and imroz lambs raised under an intensive production system
Meat Science, 2009Co-Authors: Bulent Ekiz, Alper Yilmaz, Mustafa Ozcan, Cuneyt Kaptan, Hulya Hanoglu, Ismail Erdogan, Hulya YalcintanAbstract:Effect of breed on carcass measurements and meat quality characteristics were investigated by using 46 lambs from Turkish Merino, Ramlic, Kivircik, Chios and Imroz breeds. Chios and Imroz carcasses had smaller values for carcass quality characteristics. Breed had no significant effect on pH at 45min and 24h post-mortem, water holding capacity and cooking loss. Kivircik and Imroz lambs had lower Warner Bratzler shear force values than those of Ramlic and Turkish Merino lambs (P<0.01). Meat samples from Kivircik lambs had the highest redness value. Differences among breeds for sensory characteristics, except tenderness were not significant. Tenderness scores given to meat samples of Kivircik lambs were significantly higher (P<0.01) than those of Turkish Merino, Ramlic and Imroz lambs. Indigenous Kivircik breed, which had high carcass quality as those of improved breeds, might be considered for production of better quality meat in Marmara Region of Turkey.
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carcass measurements and meat quality of turkish Merino ramlic kivircik chios and imroz lambs raised under an intensive production system
Meat Science, 2009Co-Authors: Bulent Ekiz, Alper Yilmaz, Mustafa Ozcan, Cuneyt Kaptan, Hulya Hanoglu, Ismail Erdogan, Hulya YalcintanAbstract:Abstract Effect of breed on carcass measurements and meat quality characteristics were investigated by using 46 lambs from Turkish Merino, Ramlic, Kivircik, Chios and Imroz breeds. Chios and Imroz carcasses had smaller values for carcass quality characteristics. Breed had no significant effect on pH at 45 min and 24 h post-mortem, water holding capacity and cooking loss. Kivircik and Imroz lambs had lower Warner Bratzler shear force values than those of Ramlic and Turkish Merino lambs ( P P
En Ponnampalam - One of the best experts on this subject based on the ideXlab platform.
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An alternative approach for sustainable sheep meat production: implications for food security
'Springer Science and Business Media LLC', 2020Co-Authors: En Ponnampalam, Knight M, Pj Moate, Jl JacobsAbstract:Background: A pelleted diet containing camelina hay (CAMH) or camelina meal (CAMM) as a supplement along with a control pellet (CONT) diet formulated with commonly available feeds during summer was used to investigate an alternative pathway for sustainable meat production. Sustainable meat production was based on a simple estimation of income from meat produced versus feed costs if animals were fed for an extended period over summer compared to early slaughter at the beginning of summer. Eighty maternal composite wether lambs (Composite) based on Coopworth genetics and 80 pure Merino wether yearlings were divided into 10 groups within breed (n = 8) using stratified randomisation based on liveweights. Following 1 week of adaptation to experimental diets, animals were fed experimental diets for up to10 weeks. Results: Animals were slaughtered after either 8, 9 or 10 weeks of full feeding when the average liveweight of diet/genetic combination reached a weight appropriate for either 'heavy lamb' or 'heavy hogget' production, which occurred between 8 and 10 weeks of full feeding. There was no diet × breed interactions except for dressing percentage (DP), where Composite lambs fed the CAMH diet had the greatest DP (48.1 ± 0.35) and the Merino yearlings fed the CAMM diet the lowest DP (45.8 ± 0.33). Composite lambs gained 17.6-20.3 kg and Merino yearlings gained 10.7-12.9 kg liveweight. Based on their DP, this resulted in the production of approximately 8.3-9.5 kg additional carcass weight in Composites and 4.9-5.7 kg in Merinos, which in turn produced greater profit per Composite lamb and a small profit per Merino yearling. Conclusions: Composite lambs fed CAMM and CAMH had 5% greater carcass weights at slaughter compared to the CONT group, but dietary treatments did not change carcass weight of Merino yearlings at slaughter. The extended feeding approach offered the producer an estimated economic gain of AUD $20.00 to $25.00 when yearly average prices were used (Method 1) and AUD $40.00 to $47.70 when pre- and post-summer average prices were used (Method 2) per Composite lambs, but extra carcass gain did not result in the same profit per Merino yearling. Among the Composites, the profit for animals fed the CAMH and CAMM were AUD $2.75 to $4.50 greater than CONT group when full year average prices were applied while AUD $3.50 to $5.50 greater than CONT group when pre- and post-summer average prices were applied. However, we acknowledge a combination approach of extended feeding for a portion of animals already on ground and selling the remaining animals pre-summer with joining of additional ewes is the most likely strategy. Considering the scenario of extended feeding for 3 weeks, based on the growth rates observed for Composite lambs, if an additional 2 kg carcass weight per animal can be gained for 50% of the 22 million lambs slaughtered in Australia (= 11 million animals), it would potentially supply an additional 22 million kg of lamb carcasses produced per annum. This is equivalent to producing an extra 1 million lamb carcasses per annum weighing 22 kg each. Feeding Composite lambs for an extended period and selling Merino yearlings pre-summer may be a good option due to faster growth rate of Composites that may help quick turn-over to market
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breed and nutrition effects on meat quality and retail color after lamb pre slaughter stress
Meat and Muscle Biology, 2019Co-Authors: Surinder S Chauhan, En Ponnampalam, F R Dunshea, R D WarnerAbstract:The main objective of this research was to investigate the interactions between breed, nutrition and pre-slaughter stress, and the potential impacts on the meat quality and retail color/shelf life of lamb meat. Forty-eight Merino and second cross (Merino × Border Leicester) × Poll Dorset lambs were allocated to 2 dietary treatments: low energy diet (LE; 7.8 MJ ME/kg and 12% CP) vs. high energy (HE; 11.8 MJ ME/kg and 12% CP). Samples of longissimus lumborum (LL), and rectus femoris (RF) were taken 15 min post-slaughter for glycogen and lactate determination. pH and temperature of muscle samples were recorded at 0.5, 1.5, 3, 4.5, 6, and 24 h post-mortem. Muscle LL samples from the same side were collected at 24 h post slaughter for tenderness, cooking loss and retail color assessment. For retail color stability, the selected portion of muscle LL was sliced to create a fresh surface, placed on a tray and over wrapped. Color measurements were made fresh (after a 30 min bloom at 4°C, d 1) and then on d 3 and 6 of display, using a Hunter lab spectrophotometer XE Plus. Second-cross lambs on HE had the highest muscle glycogen at slaughter for both LL and RF. For the RF, the pHu values were elevated in Merinos on both LE and HE diets and 2X on the LE diet. Only for 2X lamb was the HE diet sufficient to reduce the pHu. HE diet reduced blood lactate in 2X lambs and elevated in Merinos. Merinos produced tougher meat at 6 d post-slaughter, which was also reflected by higher cooking losses. Both breeds of lambs on the LE diet had longer color shelf-life (higher R630/580) than the lambs on the HE diets.
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sources of variation of health claimable long chain omega 3 fatty acids in meat from australian lamb slaughtered at similar weights
Meat Science, 2014Co-Authors: En Ponnampalam, D W Pethick, K L Butler, S I Mortimer, Kelly M Pearce, A J Ball, D L HopkinsAbstract:The sources of variation of health claimable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid, EPA + docosahexaenoic acid, DHA) in 2000 Australian lambs were investigated using 98 sires (Merino, maternal or terminal breeds) that were mated to about 5000 Merino or crossbred (Border Leicester × Merino) ewes. Pasture was supplemented with feedlot pellets, grains or hay as necessary, when the availability of quality green pasture was limited. Lambs were grown at 8 sites across Australia and when slaughtered the longissimus lumborum muscle was collected. Site and kills within sites were the major sources of variation for health claimable fatty acids. These environmental effects are likely to be driven by dietary background. The sire variance differed from about one twentieth to a half of the residual lamb within dam variation, depending on site and kill. This is the first comprehensive study to investigate on-farm sources of variation of long chain omega-3 polyunsaturated fatty acid content of lamb meat.
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polyunsaturated fats in meat from Merino first and second cross sheep slaughtered as yearlings
Meat Science, 2009Co-Authors: En Ponnampalam, D L Hopkins, K L Butler, F R Dunshea, Andrew J Sinclair, R D WarnerAbstract:This study examined the level of long chain omega-3 and omega-6 polyunsaturated fats, the ratio of polyunsaturated fat to saturated fat (PUFA/SFA) and the ratio of omega-6 to omega-3 (n-6/n-3) fat in sheep grown under grazing conditions in Australia. The sheep genotypes used were Poll Dorsetgrowth × Border Leicester Merino (PDg × BLM), Poll Dorsetgrowth × Merino (PDg × M), Poll Dorsetmuscling × Merino (PDm × M), Border Leicester × Merino (BL × M) and Merino × Merino (M × M). Loin muscles (Longissimus lumborum) collected from 40 ewe and wether sheep slaughtered at 14 months of age were processed for fatty acid determination. After frozen storage, 20 g samples were minced and a 7 g homogenate was processed for muscle lipid extraction using a chloroform:methanol (2:1) procedure. There was an increase in PUFA/SFA as the proportion of Merino genetics increased in the progeny (second-cross < first-cross < Merino), but this was not shown in the n-6/n-3 ratio. The PUFA/SFA trend appeared to be associated with an increase in the level of total polyunsaturated fats, but not a decrease in the level of total saturated fats. The results demonstrate that there is a need to improve the PUFA/SFA content in first- and second-cross animals which are mainly used for meat production in Australia so as to maintain the healthy lipids in meat. Nutritional manipulation through feeding systems or selection of sires for greater heritability of omega-3 fat deposition may be suitable pathways to elevate the ratio of polyunsaturated fatty acids, and in particular omega-3.
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polyunsaturated fats in meat from Merino first and second cross sheep slaughtered as yearlings
Meat Science, 2009Co-Authors: En Ponnampalam, D L Hopkins, K L Butler, F R Dunshea, Andrew J Sinclair, R D WarnerAbstract:Abstract This study examined the level of long chain omega-3 and omega-6 polyunsaturated fats, the ratio of polyunsaturated fat to saturated fat (PUFA/SFA) and the ratio of omega-6 to omega-3 ( n -6/ n -3) fat in sheep grown under grazing conditions in Australia. The sheep genotypes used were Poll Dorset growth × Border Leicester Merino (PDg × BLM), Poll Dorset growth × Merino (PDg × M), Poll Dorset muscling × Merino (PDm × M), Border Leicester × Merino (BL × M) and Merino × Merino (M × M). Loin muscles ( Longissimus lumborum ) collected from 40 ewe and wether sheep slaughtered at 14 months of age were processed for fatty acid determination. After frozen storage, 20 g samples were minced and a 7 g homogenate was processed for muscle lipid extraction using a chloroform:methanol (2:1) procedure. There was an increase in PUFA/SFA as the proportion of Merino genetics increased in the progeny (second-cross n -6/ n -3 ratio. The PUFA/SFA trend appeared to be associated with an increase in the level of total polyunsaturated fats, but not a decrease in the level of total saturated fats. The results demonstrate that there is a need to improve the PUFA/SFA content in first- and second-cross animals which are mainly used for meat production in Australia so as to maintain the healthy lipids in meat. Nutritional manipulation through feeding systems or selection of sires for greater heritability of omega-3 fat deposition may be suitable pathways to elevate the ratio of polyunsaturated fatty acids, and in particular omega-3.
Bulent Ekiz - One of the best experts on this subject based on the ideXlab platform.
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carcass measurements and meat quality of turkish Merino ramlic kivircik chios and imroz lambs raised under an intensive production system
Meat Science, 2009Co-Authors: Bulent Ekiz, Alper Yilmaz, Mustafa Ozcan, Cuneyt Kaptan, Hulya Hanoglu, Ismail Erdogan, Hulya YalcintanAbstract:Effect of breed on carcass measurements and meat quality characteristics were investigated by using 46 lambs from Turkish Merino, Ramlic, Kivircik, Chios and Imroz breeds. Chios and Imroz carcasses had smaller values for carcass quality characteristics. Breed had no significant effect on pH at 45min and 24h post-mortem, water holding capacity and cooking loss. Kivircik and Imroz lambs had lower Warner Bratzler shear force values than those of Ramlic and Turkish Merino lambs (P<0.01). Meat samples from Kivircik lambs had the highest redness value. Differences among breeds for sensory characteristics, except tenderness were not significant. Tenderness scores given to meat samples of Kivircik lambs were significantly higher (P<0.01) than those of Turkish Merino, Ramlic and Imroz lambs. Indigenous Kivircik breed, which had high carcass quality as those of improved breeds, might be considered for production of better quality meat in Marmara Region of Turkey.
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carcass measurements and meat quality of turkish Merino ramlic kivircik chios and imroz lambs raised under an intensive production system
Meat Science, 2009Co-Authors: Bulent Ekiz, Alper Yilmaz, Mustafa Ozcan, Cuneyt Kaptan, Hulya Hanoglu, Ismail Erdogan, Hulya YalcintanAbstract:Abstract Effect of breed on carcass measurements and meat quality characteristics were investigated by using 46 lambs from Turkish Merino, Ramlic, Kivircik, Chios and Imroz breeds. Chios and Imroz carcasses had smaller values for carcass quality characteristics. Breed had no significant effect on pH at 45 min and 24 h post-mortem, water holding capacity and cooking loss. Kivircik and Imroz lambs had lower Warner Bratzler shear force values than those of Ramlic and Turkish Merino lambs ( P P
D L Hopkins - One of the best experts on this subject based on the ideXlab platform.
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sources of variation of health claimable long chain omega 3 fatty acids in meat from australian lamb slaughtered at similar weights
Meat Science, 2014Co-Authors: En Ponnampalam, D W Pethick, K L Butler, S I Mortimer, Kelly M Pearce, A J Ball, D L HopkinsAbstract:The sources of variation of health claimable omega-3 polyunsaturated fatty acids (eicosapentaenoic acid, EPA + docosahexaenoic acid, DHA) in 2000 Australian lambs were investigated using 98 sires (Merino, maternal or terminal breeds) that were mated to about 5000 Merino or crossbred (Border Leicester × Merino) ewes. Pasture was supplemented with feedlot pellets, grains or hay as necessary, when the availability of quality green pasture was limited. Lambs were grown at 8 sites across Australia and when slaughtered the longissimus lumborum muscle was collected. Site and kills within sites were the major sources of variation for health claimable fatty acids. These environmental effects are likely to be driven by dietary background. The sire variance differed from about one twentieth to a half of the residual lamb within dam variation, depending on site and kill. This is the first comprehensive study to investigate on-farm sources of variation of long chain omega-3 polyunsaturated fatty acid content of lamb meat.
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polyunsaturated fats in meat from Merino first and second cross sheep slaughtered as yearlings
Meat Science, 2009Co-Authors: En Ponnampalam, D L Hopkins, K L Butler, F R Dunshea, Andrew J Sinclair, R D WarnerAbstract:This study examined the level of long chain omega-3 and omega-6 polyunsaturated fats, the ratio of polyunsaturated fat to saturated fat (PUFA/SFA) and the ratio of omega-6 to omega-3 (n-6/n-3) fat in sheep grown under grazing conditions in Australia. The sheep genotypes used were Poll Dorsetgrowth × Border Leicester Merino (PDg × BLM), Poll Dorsetgrowth × Merino (PDg × M), Poll Dorsetmuscling × Merino (PDm × M), Border Leicester × Merino (BL × M) and Merino × Merino (M × M). Loin muscles (Longissimus lumborum) collected from 40 ewe and wether sheep slaughtered at 14 months of age were processed for fatty acid determination. After frozen storage, 20 g samples were minced and a 7 g homogenate was processed for muscle lipid extraction using a chloroform:methanol (2:1) procedure. There was an increase in PUFA/SFA as the proportion of Merino genetics increased in the progeny (second-cross < first-cross < Merino), but this was not shown in the n-6/n-3 ratio. The PUFA/SFA trend appeared to be associated with an increase in the level of total polyunsaturated fats, but not a decrease in the level of total saturated fats. The results demonstrate that there is a need to improve the PUFA/SFA content in first- and second-cross animals which are mainly used for meat production in Australia so as to maintain the healthy lipids in meat. Nutritional manipulation through feeding systems or selection of sires for greater heritability of omega-3 fat deposition may be suitable pathways to elevate the ratio of polyunsaturated fatty acids, and in particular omega-3.
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polyunsaturated fats in meat from Merino first and second cross sheep slaughtered as yearlings
Meat Science, 2009Co-Authors: En Ponnampalam, D L Hopkins, K L Butler, F R Dunshea, Andrew J Sinclair, R D WarnerAbstract:Abstract This study examined the level of long chain omega-3 and omega-6 polyunsaturated fats, the ratio of polyunsaturated fat to saturated fat (PUFA/SFA) and the ratio of omega-6 to omega-3 ( n -6/ n -3) fat in sheep grown under grazing conditions in Australia. The sheep genotypes used were Poll Dorset growth × Border Leicester Merino (PDg × BLM), Poll Dorset growth × Merino (PDg × M), Poll Dorset muscling × Merino (PDm × M), Border Leicester × Merino (BL × M) and Merino × Merino (M × M). Loin muscles ( Longissimus lumborum ) collected from 40 ewe and wether sheep slaughtered at 14 months of age were processed for fatty acid determination. After frozen storage, 20 g samples were minced and a 7 g homogenate was processed for muscle lipid extraction using a chloroform:methanol (2:1) procedure. There was an increase in PUFA/SFA as the proportion of Merino genetics increased in the progeny (second-cross n -6/ n -3 ratio. The PUFA/SFA trend appeared to be associated with an increase in the level of total polyunsaturated fats, but not a decrease in the level of total saturated fats. The results demonstrate that there is a need to improve the PUFA/SFA content in first- and second-cross animals which are mainly used for meat production in Australia so as to maintain the healthy lipids in meat. Nutritional manipulation through feeding systems or selection of sires for greater heritability of omega-3 fat deposition may be suitable pathways to elevate the ratio of polyunsaturated fatty acids, and in particular omega-3.
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genotype and age effects on sheep meat production 5 lean meat and fat content in the carcasses of australian sheep genotypes at 20 30 and 40 kg carcass weights
Australian Journal of Experimental Agriculture, 2008Co-Authors: En Ponnampalam, D L Hopkins, K L Butler, Matthew G Kerr, F R Dunshea, R D WarnerAbstract:Leanmeatand fat content of Australiansheep genotypes were comparedat20-,30- and 40-kg carcass weights. Sheep comprised Poll Dorsetgrowth ·Border Leicester Merino (PDg ·BLM), Poll Dorsetgrowth ·Merino (PDg ·M), Poll Dorsetmuscling ·Merino (PDm ·M), Border Leicester ·Merino (BL ·M) and Merino ·Merino (M ·M) genotypes. Lambs wereraisedasamixedflockundergrazingandslaughteredat4,8,14and22monthsofagewitheachslaughtertimeinvolving ~150mixed sex animals. At 24h after slaughter, chilled carcasses were halved along the backbone and the right sides were usedfordeterminationoflean,fatandashpercentagesusingdualenergyX-rayabsorptiometry.Withinaparticularagegroup andgenotype,animalsgrowingatfasterratesandreachingheaviercarcassweightshadlowercarcassleanmeatcontentthan slowergrowinganimals.Merinocarcassesweighing20and30kghadsimilarlevelsofleanmeattoPD ·Mgenotypes,which wasgreaterthanthatfromtheBL ·Mgenotype.Second-crossPD ·BLMcarcassesweighing20kgat4monthsand30kgat 8monthshadsimilarcarcassfatandleanpercentagesto20-kgMerinocarcassesat8monthsandfirst-crossPD ·Mcarcasses weighing30kgat14 months, respectively. At40-kgcarcass weight, 22-month-oldMerinoshad similarlevelsofleannessto carcasses from 22-month-old PD ·M animals and carcasses from 14-month-old second-cross PD ·BLM animals. Carcass leanmeatcontentdecreasedwithincreasingcarcassweightandfirst-crossBL ·Manimalshadthelowestcarcassleanacross allweightcategories.Therewasamajoraccelerationincarcassfatnessbetween14and22monthsassociatedwithareduction inmuscle deposition.Results indicatethatage ofthe animalshouldbe taken intoaccount whencarcass leanand fat contents are compared at a particular carcass weight. Merinos will achieve weight/composition specifications at least equally well to crossbreds but will take longer with a likely increase in production costs.
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unravelling the complex interactions between genetics animal age and nutrition as they impact on tissue deposition muscle characteristics and quality of australian sheep meat
Australian Journal of Experimental Agriculture, 2007Co-Authors: R D Warner, D W Pethick, En Ponnampalam, P L Greenwood, R G Banks, D L HopkinsAbstract:The combined effects of age and genetics and Poll Dorset sire and growth path were studied in two separate experiments (n = 595 and 627, respectively). In the first experiment, containing genotype crosses typically used in Australia (Merino, Poll Dorset, Border Leicester) and sires selected for growth or muscling, sheep were slaughtered at 4, 8, 14 and 22 months. The second experiment used Poll Dorset sires selected for high muscling, fat or growth with progeny having two levels of nutrition postweaning. Border Leicesters expressed higher levels of carcass fat percentage and intramuscular fat and produced the heaviest carcass. Merinos had the lowest subcutaneous fat depth and highest carcass lean percentage when compared at the same age. The progeny of Poll Dorset sires selected for high muscling (PDm) expressed a shift toward glycolytic fibres relative to those from Merino sires, and PDm sires produced progeny with reduced spine and limb length and higher carcass muscle:mineral ratios, suggesting skeletal stunting. Genotype meat quality differences were minimal except that PDm sire topsides were tougher and Merinos produced higher pH meat. With age (4-22 months), lambs became heavier and fatter, fibres shifted towards oxidative and away from glycolytic, muscle myoglobin increased, the meat became darker and redder and tenderness declined. Early weaning had no effect on the time to reach slaughter weight, provided nutrition was not restricted. The sire genetics influence on the carcass composition far outweighed the effect of nutrition postweaning. Lambs on a restricted diet tended to have less acceptable meat quality but this was not evident in lambs from sires selected for high fatness. Sensory tenderness was improved and intramuscular fat was higher in lamb progeny from sires selected for high fatness.
