The Meat Standards Australia Index indicates beef carcass quality

A simple index that reflects the potential eating quality of beef carcasses is very important for producer feedback. The Meat Standards Australia (MSA) Index reflects variation in carcass quality due to factors that are influenced by producers (hot carcass weight, rib fat depth, hump height, marbling and ossification scores along with milk fed veal category, direct or saleyard consignment, hormonal growth promotant status and sex). In addition, processor impacts on meat quality are standardised so that the MSA Index could be compared across time, breed and geographical regions. Hence, the MSA Index was calculated using achilles hung carcasses, aged for 5 days postmortem. Muscle pH can be impacted by production, transport, lairage or processing factors, hence the MSA Index assumes a constant pH of 5.6 and loin temperature of 7^oC for all carcasses. To quantify the cut weight distribution of the 39 MSA cuts in the carcass, 40 Angus steers were sourced from the low (n=13), high (n=15) and myostatin (n=12) muscling selection lines. The left side of each carcass was processed down to the 39 trimmed MSA cuts. There was no difference in MSA cut distribution between the low and high muscling lines (P>0.05), although there were differences with nine cuts from the myostatin line (P<0.05). There was no difference in the MSA Index calculated using actual muscle percentages and using the average from the low and high muscling lines (R²=0.99). Different cooking methods impacted via a constant offset between eating quality and carcass input traits (R²=1). The MSA Index calculated for the four most commercially important cuts was highly related to the index calculated using all 39 MSA cuts (R²=0.98), whilst the accuracy was lower for an index calculated using the striploin (R²=0.82). Therefore, the MSA Index was calculated as the sum of the 39 eating quality scores predicted at 5 days ageing, based on their most common cooking method, weighted by the proportions of the individual cut relative to total weight of all cuts. The MSA Index provides producers with a tool to assess the impact of management and genetic changes on the predicted eating quality of the carcass. The MSA Index could also be utilised for benchmarking and to track eating quality trends at farm, supply chain, regional, state or national levels.     

The effect of immunocastration and a diet based on granulated barley on growth performance and carcass,meat and fat quality in heavy gilts

A total of 48 Duroc×(Landrace×Large White) gilts of 33.2 kg BW were used to investigate the influence of immunocastration and diet on growth performance and carcass, meat and fat quality. Four treatments were arranged factorially (2×2) with two sexes (immunocastrated gilts: IG v. entire gilts: EG) and two dietary treatments (a commercial feedstuff as control v. granulated barley as a single major ingredient) provided during the finishing period (from 103 to 126 kg BW). There were four replicates of three pigs per treatment. At the end of the trial, the IGs grew faster (P<0.05) and ate more feed (P<0.05) than the EGs. Carcasses from the IGs had thicker backfat depth than those from the EGs (P<0.01) and carried out a lower percentage of rejected carcasses (P<0.05) at slaughterhouse owing to lack of fat. Meat from the IGs tended to have higher intramuscular fat (IMF) content in the Longissimus thoracis (LT) muscle than that from the EGs (P=0.09). In addition, immunocastration increased the total saturated fatty-acid proportion in subcutaneous fat and IMF (P<0.001) and decreased the total monounsaturated fatty acid (MUFA) and total polyunsaturated fatty acid (PUFA) percentages in subcutaneous backfat (P<0.05 and P<0.001, respectively) and in IMF (P<0.01 and P=0.06, respectively). The use of a diet based on granulated barley during the finishing period had no effect on growth performance but tended to increase IMF content in the LT muscle (P<0.06), and increased MUFA (P<0.05) and decreased PUFA (P<0.01) proportions in omental fat. It is concluded that immunocastration of gilts intended for dry-cured ham industry improved some aspects of growth performance and carcass and meat quality, whereas granulated barley had scarce effect on productive traits and fatty-acid profile but tended to improve IMF content.     

土壤盐分对三角叶滨藜抗旱性能的影响

本实验用不同浓度NaCl溶液浇灌后进行干旱处理,测定了不同处理条件下三角叶滨藜幼苗在干旱持续过程中植株生长状况、叶片光合作用、抗氧化酶活性以及植株水分状况等的变化,以分析土壤盐分对三角叶滨藜耐旱性的影响。结果显示,用0.1—0.4 mol/L NaCl溶液浇灌后进行干旱处理（“干旱 NaCl”）的三角叶滨藜幼苗在干旱持续期间植株生长量、叶片净光合速率均明显高于用水浇灌后进行干旱处理（“干旱”）的三角叶滨藜幼苗,且后者在干旱处理的后期导致了叶片光合机构的明显损伤,前者则无。同时,“干旱 NaCl”处理的植株叶片超氧化物歧化酶、过氧化物酶和过氧化氢酶活性的变化幅度明显小于“干旱”处理的,且前者的丙二醛含量显著低于后者。进一步分析各处理土壤和植株水分状况发现,与“干旱”处理相比,“干旱 NaCl”处理显著提高了土壤的保水能力,增加了植株对Na 的吸收和积累,降低了叶片渗透势。由此可见,土壤中适量盐分存在能够增加三角叶滨藜对Na 的吸收和积累、降低组织渗透势、维持较强的吸水和保水力,从而减弱因干旱脱水导致的过量活性氧自由基产生对细胞膜系统的损伤和对光合机构的破坏,有利于维持相对较高的物质生产能力和细胞的持续生长,最终表现为耐旱性能的增强。     

Planted saltbush (Atriplex nummularia) and its value for birds in farming landscapes of the South Australian Murray Mallee

Summary In the fragmented agricultural landscapes of temperate southern Australia, broad‐scale revegetation is underway to address multiple natural resource management issues. In particular, commercially‐driven fodder shrub plantings are increasingly being established on non‐saline land to fill the summer‐autumn feed gap in grazing systems. Little is known of the contribution that these and other planted woody perennial systems make to biodiversity conservation in multifunctional landscapes. In order to address this knowledge gap, a study was conducted in the southern Murray Mallee region of South Australia. Selected ecological indicators, including plant and bird communities, were sampled in spring 2008 and autumn 2009 in five planted saltbush sites and nearby areas of remnant vegetation and improved pasture. In general, remnant vegetation sites had higher biodiversity values than saltbush and pasture sites. Saltbush sites contained a diverse range of plants and birds, including a number of threatened bird species not found in adjacent pasture sites. Plant and bird communities showed significant variation across saltbush, pasture and remnant treatments and significant differences between seasons. This study demonstrates that saltbush plantings can provide at least partial habitat for some native biota within a highly modified agricultural landscape. Further research is being conducted on the way in which biota, such as birds, use available resources in these dynamic ecosystems. An examination of the effects of grazing on biodiversity in saltbush would improve the ability of landholders and regional natural resource management agencies in making informed land management decisions.     

The effect of floor type on the performance,cleanliness, carcass characteristics and meat quality of dairy origin bulls

The aim of this study was to evaluate the effect of using different floor types to accommodate growing and finishing beef cattle on their performance, cleanliness, carcass characteristics and meat quality. In total, 80 dairy origin young bulls (mean initial live weight 224 kg (SD=28.4 kg)) were divided into 20 blocks with four animals each according to live weight. The total duration of the experimental period was 204 days. The first 101 days was defined as the growing period, with the remainder of the study defined as the finishing period. Cattle were randomly assigned within blocks to one of four floor type treatments, which included fully slatted flooring throughout the entire experimental period (CS); fully slatted flooring covered with rubber strips throughout the entire experimental period (RS); fully slatted flooring during the growing period and moved to a solid floor covered with straw bedding during the finishing period (CS-S) and fully slatted flooring during the growing period and moved to fully slatted flooring covered with rubber strips during the finishing period (CS-RS). Bulls were offered ad libitum grass silage supplemented with concentrates during the growing period. During the finishing period, bulls were offered concentrates supplemented with chopped barley straw. There was no significant effect of floor type on total dry matter intake (DMI), feed conversion ratio, daily live weight gain or back fat depth during the growing and finishing periods. Compared with bulls accommodated on CS, RS and CS-RS, bulls accommodated on CS-S had a significantly lower straw DMI (P<0.01). Although bulls accommodated on CS and CS-S were significantly dirtier compared with those accommodated on RS and CS-RS on days 50 (P<0.05) and 151 (P<0.01), there was no effect of floor type on the cleanliness of bulls at the end of the growing and finishing periods. There was also no significant effect of floor type on carcass characteristics or meat quality. However, bulls accommodated on CS-S had a tendency for less channel, cod and kidney fat (P=0.084) compared with those accommodated on CS, RS and CS-RS. Overall, floor type had no effect on the performance, cleanliness, carcass characteristics or meat quality of growing or finishing beef cattle.     

The variation in the eating quality of beef from different sexes and breed classes cannot be completely explained by carcass measurements

Delivering beef of consistent quality to the consumer is vital for consumer satisfaction and will help to ensure demand and therefore profitability within the beef industry. In Australia, this is being tackled with Meat Standards Australia (MSA), which uses carcass traits and processing factors to deliver an individual eating quality guarantee to the consumer for 135 different ‘cut by cooking methods’ from each carcass. The carcass traits used in the MSA model, such as ossification score, carcass weight and marbling explain the majority of the differences between breeds and sexes. Therefore, it was expected that the model would predict with eating quality of bulls and dairy breeds with good accuracy. In total, 8128 muscle samples from 482 carcasses from France, Poland, Ireland and Northern Ireland were MSA graded at slaughter then evaluated for tenderness, juiciness, flavour liking and overall liking by untrained consumers, according to MSA protocols. The scores were weighted (0.3, 0.1, 0.3, 0.3) and combined to form a global eating quality (meat quality (MQ4)) score. The carcasses were grouped into one of the three breed categories: beef breeds, dairy breeds and crosses. The difference between the actual and the MSA-predicted MQ4 scores were analysed using a linear mixed effects model including fixed effects for carcass hang method, cook type, muscle type, sex, country, breed category and postmortem ageing period, and random terms for animal identification, consumer country and kill group. Bulls had lower MQ4 scores than steers and females and were predicted less accurately by the MSA model. Beef breeds had lower eating quality scores than dairy breeds and crosses for five out of the 16 muscles tested. Beef breeds were also over predicted in comparison with the cross and dairy breeds for six out of the 16 muscles tested. Therefore, even after accounting for differences in carcass traits, bulls still differ in eating quality when compared with females and steers. Breed also influenced eating quality beyond differences in carcass traits. However, in this case, it was only for certain muscles. This should be taken into account when estimating the eating quality of meat. In addition, the coefficients used by the Australian MSA model for some muscles, marbling score and ultimate pH do not exactly reflect the influence of these factors on eating quality in this data set, and if this system was to be applied to Europe then the coefficients for these muscles and covariates would need further investigation.     

Influence of cage or pen housing on carcass traits and meat quality of rabbit

Carcass traits and meat quality of rabbits reared in conventional cages (0.385 m2), small pens (0.662 m2) or large pens (4.052 m2) at a similar stock density of 15 rabbits/m2 were compared (n = 30 per group). Pens contained an elevated platform. Slaughter weight (SW; P < 0.01) and cold carcass weight (P < 0.05) decreased in the order of Cage < Small pen < Large pen groups. SW and cold carcass weight were 7% lower in rabbits housed in large pens than in cages. Dressing out and meat-to-bone ratio were not influenced by the housing system. Percentage of fat deposits was highest in caged rabbits (+0.15 point for scapular fat and +0.26 point for perirenal fat compared to rabbits reared in large pens P < 0.05). Rabbits housed in large pens had a bigger proportion of hind part (+1 point), and meat colour was shifted towards greater a* values (P < 0.01) compared to caged rabbits. Water holding capacity and shear test parameters in longissimus lumborum muscle, lipid content and shear test parameters of abductor cruralis cranialis, biceps femoris and semitendinosus muscles were not affected by the housing system. Tibia and femur bone moment of inertia increased in the order of Cage < Small pen < Large pen groups (P < 0.05), whereas elastic modulus, which is a measure of intrinsic stiffness, was highest in caged rabbits. This study showed that large pen housing altered carcass traits independently and increased meat redness and fracture resistance of tibia and femur.     

Sex effect on meat quality and carcass traits of foals slaughtered at 15 months of age

The effect of sex on carcass measurement, physico-chemical properties, nutritional value and sensory characteristics of foal meat slaughtered at 15 months was investigated. Twelve foals (six females and six males) from an extensive production system in freedom regimen were used for this study. Sex had no statistical influence on carcass measurements, chemical composition, colour parameters, textural properties, amino acid content and sensory characteristics. In contrast, there was a clear effect on the fatty acid profile of longissimus dorsi. Slaughter weight was not significantly (P > 0.05) different between sexes, although higher values were observed in male group compared with female group (194 v. 184 kg). As a consequence, this trend affected carcass weight being slightly (P > 0.05) heavier in the male group than in the female group. On the other hand, cooking loss samples from males showed significantly higher values than those from females (21.50% v. 14.96%, P < 0.05). From a nutritional point of view, the n-6/n-3 ratio in both sexes was within the recommended range for the human diet and this ratio was ostensibly different between the sexes (1.83 v. 1.36, P < 0.05, for male and female, respectively) and it showed a strong correlation (r = −0.91, P < 0.01) with C18:3n-3 content.     

The effect of livestock production system and concentrate level on carcass traits and meat quality of foals slaughtered at 18 months of age

This trial was conducted to study the effect of livestock production system (freedom extensive system (FES) v. semi extensive system (SES)) and amount of finishing feed (1.5 v. 3.0 kg of commercial feed) in SES on carcass characteristics, meat quality and nutritional value of meat foal slaughtered at 18 months of age. For this study, a total of 49 foals (21 from FES and 28 from SES) were used. The obtained results showed that SES had a positive influence on carcass characteristic because these foals showed the best values for live weight, carcass weight, dressing percentage, perimeter of leg (PL) and carcass compactness index. On the other hand, finishing feeding also had a significant (P<0.05) effect on PL and lean thickness, as the highest values were obtained in foals finished with 3 kg of commercial fodder. The physico-chemical properties were significantly affected by the livestock production system with the exception of ashes content (P>0.05). Foals finished in SES increased in 408% the intramuscular fat content (0.23 v. 1.17%, for foals reared in FES and SES, respectively). On the other hand, L*-value and a*-value were significantly (P<0.01) affected by livestock production system, as foals from the FES group had a more intense redder color (higher CIE a*-value) and higher lightness (higher CIE L*-value) compared with those from the SES group. Finally, meat nutritional value was significantly affected by livestock production system, as foals from an extensive production system on wood pasture could be considered as healthier in relation to their fatty acid profiles (low n-6/n-3 ratio and high hypocholesterolemic/hypercholesterolemic ratio) as a result of the beneficial grass intake on meat fatty acid profile.     

Young Salers suckled bull production: effect of diet on performance, carcass and muscle characteristics and meat quality

The aim of this work was to improve the knowledge on young suckled Salers bull production and to study the effect of forage type and concentrate level on performance, carcass and muscle characteristics as well as on meat quality. Twenty-four Salers male calves of 150 days of age were assigned to six groups: C0 (fed exclusively with hay and dam's milk and slaughtered at approximately 6 months of age), and HH (hay - high concentrate), HL (hay - low concentrate), GH (cut grass - high concentrate), GL (cut grass - low concentrate) and CP (control pasture: pasture - high concentrate) groups differing in feeds received until slaughter and slaughtered unweaned at approximately 10 months of age. Carcass weights averaged 210 kg at 10 months of age at slaughter. Average daily weight gain (ADWG) in HH and GH groups tended to be higher (P = 0.09) than in HL and GL groups (1354 v. 1248 g/day). ADWG in CP group (1542 g/day) was higher (P < 0.05) than in the other groups. Carcass weight in CP group (230 kg) tended to be higher (P < 0.1) than in HL (198 kg) and GL (200 kg) groups. Carcass muscle weight was higher (P < 0.05) in GH (155 kg) and CP groups (165 kg) than in HL (141 kg) and GL (142 kg) groups. Carcass and offal fatty tissue weights and carcass fatness did not differ between groups. Neither forage type nor concentrate level had significant effect on the area of muscle fibres or on muscle metabolic enzyme activities (namely, lactate dehydrogenase - LDH, phosphofructokinase - PFK, isocitrate dehydrogenase - ICDH, citrate synthase - CS and cytochrome-c oxidase - COX). semitendinosus muscle of CP group presented higher CS enzyme activities (8.10 μmol/min per g) than HH (5.30 μmol/min per g) and GL (4.52 μmol/min per g) groups. Neither total nor insoluble collagen content significantly differed between groups. Lipid content in rectus abdominis muscle was relatively low (average 67.5 mg/g dry matter) and was not affected by diet (P > 0.05). The ratio between n-6 and n-3 polyunsaturated fatty acid content was lower (P = 0.01) in the low-concentrate-fed than in the high-concentrate-fed group (3.95 v. 5.37, respectively). Sensory analysis noted that longissimus thoracis muscle from CP animals was more tender and juicy than that from HH and GH animals (P < 0.05).     

The effect of granulated barley as single major ingredient in the growing or finishing diet on productive performance,carcass, meat and fat quality of heavy pigs

A total of 48 Duroc × (Large White × Landrace) gilts of 46.8 kg BW (86 ± 3 days of age) were used to investigate the effect of diet during the growing and finishing periods on growth performance and carcass, meat and fat quality. The control diet consisted of a commercial feedstuff and the granulated barley diet had that cereal as the single major ingredient. There were three treatments: (i) control diet provided from 45.6 to 127.8 kg BW (C group), (ii) control diet from 47.0 to 91.8 kg BW and granulated barley from 91.8 to 129.7 kg BW (C + GB group) and (iii) granulated barley from 47.9 to 93.1 kg BW and control diet from 93.1 to 135.1 kg BW (GB + C group). Each treatment was replicated eight times, with two pigs per replicate. The C group grew faster (P < 0.001) and had a better feed conversion ratio (P < 0.001) than the GB + C group, with C + GB being intermediate. Carcasses from C + GB gilts had higher backfat depth than those from C gilts, with GB + C being intermediate (P < 0.05). Also, the main joints (ham + shoulder + loin) had a higher (P < 0.01) yield in carcass in the GB + C group than in the C group, with C + GB being intermediate. The intramuscular fat (IMF) content was higher (P < 0.001) in loin from C + GB and GB + C gilts than in C gilts. The IMF of loin from C + GB gilts had higher (P < 0.05) C18:1n-9 and total monounsaturated fatty acid (FA) proportions than that from C gilts, whereas the C18:2n-6 and total polyunsaturated FA percentages were lower (P < 0.05) in C + GB gilts than in the remaining gilts. The total saturated FA percentage was lower (P < 0.05) in loin from GB + C than in that from C gilts. Hams from C + GB and GB + C gilts had higher (P < 0.05) C18:1n-9 and total monounsaturated FA proportions and lower C18:2n-6 and total polyunsaturated FA contents than those from C gilts. We can conclude that granulated barley provided during the growing or the finishing period improved some carcass and meat characteristics of heavy gilts desirable for dry-cured ham production.     

Effect of slaughter age on foal carcass traits and meat quality

Meat has played a crucial role in human evolution and is an important component of a healthy and well-balanced diet due to its nutritional richness. Recent studies have shown that horsemeat may be considered as an alternative to other meat (such as beef or pork), and it may have a positive effect on human health from a nutritional point of view. This research was conducted to characterize the carcass measurement, meat quality (chemical composition, colour characteristics and textural traits) and nutritional value (fatty acid and amino acid composition) of foals slaughtered at 8 and 11 months of age (8 and 11 m groups). For this study, a total of 21 foals (10 and 11 animals from the 8 and 11-m groups, respectively) were used. The results obtained showed a positive influence on carcass characteristics with an increase in slaughter age, because 11 m animals had slightly higher values of live (275 v. 247 kg) and carcass weights (148 v. 133 kg), length of leg (72.86 v. 69.85 cm) and carcass (100.41 v. 96.30 cm) and perimeter of leg (97.68 v. 89.22 cm) compared with animals from the 8-m group. Regarding meat quality, only Fe-haeme and cholesterol content in chemical composition and luminosity (L*) in colour parameters showed significant differences. Foals from the 8-m group had the highest content of cholesterol (0.47 v. 0.28 mg/100 g of meat) and luminosity values (39.66 v. 37.88) and the lowest content of ash (1.20% v. 1.40%). In fatty acids content, only five out of 23 fatty acids showed differences between the two groups. However, an interesting change in the fatty acid profile occurred with an increase in the slaughter age. Foals from the 8-m group had the highest values of α-linolenic acid and n-3 fatty acids and the lowest values of linoleic and n-6 fatty acids, which is an interesting fact from a health point of view. Finally, slaughter age had no statistical influence on textural properties or amino acid content. As a main conclusion, animals slaughtered at 8 months of age had higher nutritional quality meat (with higher content of n-3 fatty acids) than meat from foals slaughtered at 11 months of age. The slaughter of animals at 8 months of age also reduced production costs because they ate a smaller amount of commercial fodder.     

Effects of the Texel muscling quantitative trait locus on carcass traits in crossbred lambs

Texel muscling quantitative trait locus (TM-QTL) is a QTL on chromosome 18, originally identified in purebred UK Texel sheep, which was reported to increase ultrasonically measured muscle depth at the third lumbar vertebra by around 4% to 7%. The objective of the present study was to comprehensively evaluate the TM-QTL and to determine whether it could provide benefits to the UK sheep industry through increased carcass meat yield in crossbred slaughter lambs. Effects of this QTL on a range of carcass traits, including those measured in vivo and by dissection, were evaluated in heterozygous carrier and non-carrier lambs produced by crossing heterozygous carrier Texel rams with non-carrier Mule (Bluefaced Leicester × Scottish Blackface) ewes from a lowland flock. The TM-QTL was found to increase loin muscling in crossbred lambs at a given live weight or carcass weight, as measured by ultrasound, X-ray computed tomography (CT) and carcass dissection. Depth of M. longissimus lumborum (MLL) was greater in TM-QTL carrier lambs compared to non-carriers as measured by both ultrasound at the third lumbar vertebra (+4.5%; P = 0.033) and CT scanning at the fifth lumbar vertebra (+6.7%; P = 0.004). Width and area of MLL measured using CT were also greater in TM-QTL carrier lambs compared to non-carriers (+3.0%; P = 0.013 and +5.1%; P = 0.047, respectively). Loin muscle volume measured using CT was greater in TM-QTL carriers than in non-carriers (+5.9%; P = 0.005) and the dissected weight of the MLL was +7.1% greater in TM-QTL carriers compared to non-carriers (P < 0.001). The proportion of the total carcass lean meat yield (LMY) that was contained within the loin region was slightly higher in TM-QTL carriers than in non-carriers (0.154 v. 0.145; P = 0.006). However, TM-QTL was found to have no significant effect on the total weight or proportion of LMY or of saleable meat yield in the carcass measured by dissection, or on muscling in the hind leg measured by CT or dissection. This work has verified that the inheritance of TM-QTL is associated with increased loin muscling in crossbred lambs, as has previously been reported for purebred Texel lambs.     

A comparative study of four rumen buffering agents on productive performance,rumen fermentation and meat quality in growing lambs fed a total mixed ration

Controlling rumen fermentation using buffering agents could contribute to enhancing ruminant productivity and performance. This study was realized to investigate the effect of dietary supplementation of AcidBuf, sodium bicarbonate, calseapowder and WMC seaweed (Utva Lactuca extra) on the animal performance, volatile fatty acids, rumen pH, rumen histology and carcass characteristics of growing male Awassi lambs. A total of 60 lambs was divided into five groups. One group served as a control and fed only on a concentrate diet without any buffering, whereas the other four groups were fed the concentrate diet supplemented with 0.4% AcidBuf (Buf1), 0.4% AcidBuf plus sodium bicarbonate, 50 : 50 (Buf2), 0.4% calseapowder (Buf3) or 0.4% WMC Seaweed (Buf4) for 98 days. The feed conversion ratio was (P<0.05) improved in Buf2 compared to the control and other treatment groups. The propionic acid decreased, whereas butyric acid was increased in the treatment groups (P<0.05) compared to the control. The pH of the rumen fluid and the length of submucosa were (P<0.05) higher in Buf4 and Buf1, respectively, compared to the control. Hot and cold carcass weights were (P<0.05) higher in Buf4 compared to Buf1. Lean meat percentage and rib eye area were (P<0.05) higher in Buf4; while the fat percentage was (P<0.05) lower in Buf2 and Buf4 groups compared to the control. The lightness and yellowness of meat were (P<0.05) higher in Buf1 and Buf4 compared to the control. The meat pH was (P<0.05) higher in Buf3 and Buf4 compared to Buf2 (at 1 h) and control (at 24 h). The visceral depot fat (%) was reduced with Buf3 and Buf4 compared to the control. The results indicated that dietary supplementation of different buffering agents improved feed efficiency, rumen pH, carcass characteristics and decreased the body fat in growing Awassi lambs.     

Growth performance and carcass quality of fattening lambs from fat-tailed and tailed sheep breeds

The growth performance and carcass traits of two fat-tailed breeds (Chaal and Zandi) and their crosses with rams of a tailed breed (Zel) were compared. After weaning, the growth and feed consumption of male and female lambs fattened for 114 days were recorded. A total of 45 male and female lambs were slaughtered and the left side of the carcasses were cut into six pieces, and the lean meat, bone, subcutaneous and intermuscular fat were determined. Average daily gain and feed conversion ratio in crossbred lambs improved, but the differences with pure lambs were not significant. The average weight of shoulder, brisket and loin were higher in crossbred than pure breed lambs (P < 0.01). The percentage of protein in the carcass of Zel × Zandi lambs was significantly higher than Zandi lambs. The smaller size and lower weight of fat-tail in crossbred lambs were compensated by higher percentage of subcutaneous, intermuscular and internal fat. The fat-tailed breeds provided good quality lean meat in terms of lower percentage of intermuscular fat.     

Relationships between lamb carcass quality traits measured by X-ray computed tomography and current UK hill sheep breeding goals

Genetic parameters were estimated between current UK hill sheep breeding goals and lamb carcass composition and muscularity traits derived using X-ray computed tomography (CT). To produce these estimates, a total of 648 lambs from two hill farms were CT scanned at weaning (ca 120 days of age), over 3 years, and total weights of carcass muscle (MUSC), fat (CFAT) and bone (BONE) and internal fat (IFAT) were predicted. Previously derived muscularity indices were also calculated for the hind leg (HLMI) and lumbar (LRMI) regions, to assess muscle shape. Data for current breeding goals (lamb performance and maternal traits) were also included from a total of 10 297 lamb records and 12 704 ewe records. Heritabilities were estimated for each trait and genetic and phenotypic correlations were calculated between each CT trait and other lamb or ewe traits. Moderate to high positive genetic correlations were found between CT-predicted tissue weights and breeding goals, which were also weights (lamb weaning weight, carcass weight, mature ewe weight, average weight of lambs reared by the ewe). CFAT was positively genetically correlated with ultrasound backfat depth at weaning (UFD) and subjective fatness grade at slaughter (MLCF), suggesting that carcass fat could be decreased using selection on any of these predictors. Ultrasound muscle depth at weaning (UMD) and subjective conformation score at slaughter (MLCC) had high genetic correlations with the muscularity indices (HLMI and LRMI), but correlations with MUSC were not significantly different from zero. This implies that selection to improve MLCC is likely to be increasing the 'roundness' of muscle shape in the high-priced carcass region, but having little impact on total lean meat yield. Correlations of CT traits with the other ewe traits (number of lambs weaned, number of lambs lost, longevity, fleece weight) were generally small or not significantly different from zero. The genetic parameters generated in this study can now be used in selection index calculations to assess the benefits of including lamb CT traits in future selection programmes for hill sheep.     

Effects of feeding and rearing systems on growth, carcass composition and meat quality in pigs

Animal growth performance and quality of pork depend on the interactive effects of pig genotype, rearing conditions, pre-slaughter handling, and carcass and meat processing. This paper focuses on the effects of feeding and rearing systems (feeding level and diet composition, housing, production system, etc.) on growth performance, carcass composition, and eating and technological qualities of pork. The feeding level and protein : energy ratio can be used to manipulate growth rate or composition of weight gain. Restricted feed allowance strongly reduces growth rate and carcass fatness and also intramuscular fat (IMF) level, resulting in decreased meat tenderness or juiciness. Expression of compensatory growth due to restricted followed by ad libitum feeding modifies the composition of weight gain at both carcass and muscle levels, and may improve meat tenderness due to higher in vivo protein turnover. Decreasing the protein : energy ratio of the diet actually increases IMF and improves eating quality, but gives fatter carcasses. In contrast, a progressive reduction in the protein : energy ratio leads to similar carcass composition at slaughter but with higher IMF. Technological meat traits (pH1, pHu, colour, drip loss) are generally not affected by the level or protein : energy in feed. Modification of fatty acid composition and antioxidant level in meat can be obtained through diet supplementations (e.g. vegetable sources with high n-3 fatty acids), thereby improving the nutritional quality of pork. Influences of pig rearing system on animal performance, carcass and meat traits result from interactive effects of housing (floor type, space allowance, ambient temperature, physical activity), feeding level and genotype in specific production systems. Indoor enrichment (more space, straw bedding) generally increases growth rate and carcass fatness, and may improve meat juiciness or flavour through higher IMF. Outdoor rearing and organic production system have various effects on growth rate and carcass fatness, depending on climatic conditions and feed allowance. Influence on meat quality is also controversial: higher drip and lower pHu and tenderness have been reported, whereas some studies show improved meat juiciness with outdoor rearing. Discrepancies are likely due to differences between studies in rearing conditions and physiological responses of pigs to pre-slaughter handling. Specific production systems of the Mediterranean area based on local breeds (low growth rate, high adiposity) and free-range finishing (pasture, forests), which allows pig to express their genetic potential for IMF deposition, clearly demonstrate the positive effects of genotype × rearing system interactions on the quality of pork and pork products.     

Associations between the 11-bp deletion in the myostatin gene and carcass quality in Angus-sired cattle

An 11-bp deletion in the bovine myostatin ( MSTN ) gene was identified as the causative mutation for the double-muscling phenotype in Belgian Blue and Asturiana cattle. More recently, this mutation was also identified in the South Devon breed of cattle, in which it has been found to be associated with a general increase in muscle mass. The present study found that the mutant allele was also segregating in a commercial population of Scottish Aberdeen Angus beef cattle. The mutation was found at a low frequency (0.04) with no animals homozygous for the mutation in the sample population (536 animals). The effects of this mutation on various carcass traits of economic interest were then tested. We found that the mutation significantly increased carcass weight, sirloin weight, hindquarter weight, muscle conformation score and eye muscle area, but had no effect on the fat traits.