Lamb Carcass Composition Research Articles

Effect of condensed tannins from Birdsfoot trefoil and dietary protein level on growth performance, carcass composition and meat quality of ram lambs

The study aimed to evaluate the interaction between dietary crude protein (CP) and condensed tannins (CT) on the growth performance, carcass composition and meat quality of ram lambs. Twenty-four White Alpine lambs were fed a basal diet consisting of 56% birdsfoot trefoil (BT) silage and 44% hay (67.1% grasses, 4.3% legumes and 28.6% herbs). In addition, lambs were offered either a barley concentrate to reach the predicted protein requirements (BP) or a barley and soybean meal concentrate to extend the CP level 20% above the requirements (HP). The diets were either untreated (BP−; HP−) or treated (BP+; HP+) with the CT-binding polyethylene glycol (PEG). Lambs fed HP− and HP+ diets had greater (P < 0.001) average daily feed intake (ADFI) and average daily gain (ADG) than lambs fed BP− and BP+ diets. Consequently, slaughter weight and cold carcass weight were greater (P ≤ 0.05) in HP− and HP+ groups. Despite similar slaughter weight, lambs fed BP− and HP− diets had lower (P < 0.05) cold carcass weight compared to lambs fed BP+ and HP+ diets. The skatole concentrations in the perirenal fat were not affected by the dietary treatments. The observed interaction between CP level and CT concentration resulted in lower (P < 0.05) indole level in perirenal fat of lambs fed the HP− diet, attributed to the greater CT intake. No effects of dietary treatments were detected on the flavour scores of the meat whereas the loin from lambs fed HP− and HP+ diets had lower ‘sheepy’ odour compared with the loin of those fed the BP− and BP+ diets. These findings let us conclude that at elevated intake, CT reduced the indole but not skatole level in the perirenal fat. The lack of effect of BT at basal and high dietary CP level on the other traits investigated might be explained by the rather low CT content.

1700 Effect of dried distillers grains on diet digestibility, body weight gain, and carcass composition of lambs

1700 Effect of dried distillers grains on diet digestibility, body weight gain, and carcass composition of lambs

Sire carcass breeding values affect body composition in lambs — 2. Effects on fat and bone weight and their distribution within the carcass as measured by computed tomography

This study assessed the effect of paternal Australian Sheep Breeding Values for post weaning c-site eye muscle depth (PEMD) and fat depth (PFAT), and post weaning weight (PWWT) on the composition of lamb carcasses. Composition was measured using computed tomography scans of 1665 lambs which were progeny of 85 Maternal, 115 Merino and 155 Terminal sires. Reducing sire PFAT decreased carcass fat weight by 4.8% and increased carcass bone by 1.3% per unit of PFAT (range 5.1mm). Increasing sire PEMD reduced carcass fat weight by 3.8% in Maternal and 2% in Terminal sired lambs per unit of PEMD (range 4.3 and 7.8mm), with no impact on bone. Increasing sire PWWT reduced carcass fat weight, but only at some experimental locations. Differences in composition varied between sire types with Maternal sired lambs having the most fat and Merino sired lambs the greatest bone weight. Genetic effects on fatness were greater than the environmental or production factor effects, with the converse true of bone.

Rosiglitazone maleate increases weight gain and body fat content in growing lambs

Thiazolidinediones (TZD) are synthetic orally active peroxisome proliferator-activated receptor γ ligands used in the treatment of diabetes mellitus. The peroxisome proliferator-activated receptor γ gene plays an important role in regulating fat cell development, energy balance, and lipid metabolism in adipose and skeletal muscle tissue. There is interest in pharmacologic or nutritional means that may complement genetic techniques to improve growth and carcass composition of lambs and the major aim of the present study was to determine whether TZD impact on growth performance and meat quality of growing lambs. An initial study with four cross-bred lambs confirmed that rosiglitazone maleate is absorbed after oral dosing for 7 days. A second study was conducted with 30 cross-bred lambs to investigate the effects of sex (ewe vs wether) and dose of orally administered rosiglitazone maleate (0, 8 and 24 mg/day) for 55 days on growth performance, body composition, plasma metabolites and insulin and meat quality. Feed intake tended to increase linearly with dose of TZD (1521, 1816 and 1878 g/day for 0, 8 and 24 mg/day, P = 0.07) over the entire study, and particularly during the second half of the study (P &lt; 0.05). There were both linear (P = 0.05) and quadratic (P = 0.04) responses in average daily gain to TZD (215, 270 and 261 g/day) with the quadratic response being most pronounced over the second half of the study (P = 0.004). As a result of the increased feed intake back fat (9.4, 11.1 and 13.5 mm, P &lt; 0.001) and carcass fat (27.5%, 29.2% and 30.1%, P = 0.05) increased linearly with dose of TZD. However, there was no effect of TZD on internal fat depots. Plasma non-esterified acid concentrations increased linearly (0.37, 0.39 and 0.41 mM, P = 0.01) whereas plasma insulin concentrations (23.2, 26.9 and 20.9 mU/L, P = 0.05) and the homeostatic model assessment (6.82, 7.73 and 5.98, P = 0.05) exhibited quadratic responses to TZD. There were no significant effects of TZD on muscle pH, temperature or colour although muscle pH was higher at any temperature in ewes (+ 0.05 of a pH unit, P = 0.036) than in wethers. In conclusion, these data confirm that rosiglitazone maleate was rapidly absorbed from the digestive tract of growing ruminant lambs and was metabolically active. Oral TZD treatment appeared to mitigate against the inhibitory effect of carcass fatness on feed intake but the additional energy consumed was in turn deposited as fat.

Evaluation of ultrasound scanning to predict carcass composition of Austrian meat sheep

Aims of the study were to evaluate the routine ultrasound scanning plus subjective muscle scoring system for meat sheep in Austria in terms of (1) their ability to predict carcass quality and composition, (2) the repeatability of ultrasound scanning and (3) a comparison of three anatomical scanning sites. Lambs of six breeds (n=189; mean bodyweight 39kg) were scored for the muscling of their shoulder, back and hindquarter and were scanned with an ultrasound device for back fat and longissimus dorsi muscle depth lateral of the spine at 10th/11th (US1) and 13th (US2) thoracic vertebrae as well as at 3rd/4th (US3) lumbar vertebrae. Each ultrasound picture was taken twice within a few minutes to check on within operator repeatability. After slaughter the carcasses were classified according to the EUROP system and back fat and muscle depth were measured on a carcass cross section, and 36 carcasses were dissected to lean meat, fat and bone to evaluate carcass composition. Relationships between carcass and dissection traits and routine performance testing traits (live weight, fat and muscle depth at US3) were evaluated based on partial regression coefficients additionally considering breed, sex (carcass traits only) and birth type as fixed effects. Further, fat and muscle depth at scan sites US1 and US2 were fitted alternatively and Pearson's correlation coefficients were calculated. Correlations between ultrasonic and carcass measures ranged from r=0.60 (muscle depth at US1 and EUROP conformation class) to r=0.84 (muscle depth at US1 and muscle depth at carcass). Repeatabilities for muscle and backfat thickness ranged from 0.90 to 0.95. The results support the usefulness of the currently routine ultrasound scans as relatively easy method to predict carcass composition in live lambs of different breeds. Muscle scans are valuable to estimate amount of carcass lean and EUROP conformation class, but fat scans have greater power to predict the fattiness of the carcass as well as lean percentage. Subjective muscle scoring of live animals seems to be mainly influenced by the fattiness of the animal. The comparison of three anatomical scanning sites did not give definite results. US1 seems to be favourable for estimating muscle depth, for the prediction of lean and in terms of repeatability whereas US2 and US3 had small advantages in scanning fat depth and in the prediction of EUROP classification and carcass fat.

Effect of hypothyroidism on growth performance, carcass composition and meat quality of fat-tailed Lori-Bakhtiari lambs

The aim of the present study was to investigate the effects of induction hypothyroidism by propylthiouracil (PTU) on the growth performance and meat quality of fat-tailed Lori-Bakhtiari lambs. Eighteen Lori-Bakhtiari male lambs were randomly assigned to one of three groups (n = 6) and received daily treatments (gavage) consisting of 0 (Control: C), 10 (Low: L) or 20 (High: H) mg PTU/kg bodyweight/day for 60 days. PTU decreased plasma triiodothyronine and thyroxine concentration in both L and H (P &lt; 0.0001). Lambs treated with PTU (L and H) had lower feed intake (P &lt; 0.004), feed conversion efficiency (P &lt; 0.003), and greater intramuscular fat than C lambs (P &lt; 0.035). Meat from the L and H lambs had lower cooking loss and shear force, and also higher L* (lightness) than C lambs (P &lt; 0.004, P &lt; 0.015 and P &lt; 0.025, respectively). The meat of H and L lambs was more tender than C lambs (P &lt; 0.032). However, the meat of H lambs required fewer chews before swallowing than C lambs (P &lt; 0.041). Generally, induction of mild hypothyroidism appeared to improve feed conversion efficiency and meat quality of lambs.

Carcass composition of Namaqua Afrikaner, Dorper and SA Mutton Merino ram lambs reared under extensive conditions

This study evaluated the differences in the muscle-fat-bone yield of Namaqua Afrikaner (NA), Dorper (D) and SA Mutton Merino (SAMM) ram lambs. The breeds constituted an indigenous, hardy and late maturing, fat-tailed breed (NA), an early maturing, commercial meat breed (D) and a late maturing commercial dual-purpose breed (SAMM). Lambs were slaughtered at 35 (± 8) days post weaning. Carcasses were cooled for 24 h, separated into retail cuts (leg, loin, rib, and shoulder), weighed and deboned. Meat and fat were separated after deboning and weighed to calculate the muscle-fat-bone yield per cut. Least-square means were computed for the respective breeds, using slaughter age as covariate. Results for percentage meat indicate that, with exception of the rib, retail cuts from the NA breed contained a lower percentage of meat than D and SAMM breeds, particularly in the valuable loin and leg cuts. The shoulder of the NA had a lower percentage meat than that of the D. The percentage fat in retail cuts did not differ between breeds for any of the cuts. In comparison with both D and SAMM, NA contained a higher percentage bone in all cuts. Dorper and SAMM carcasses did not differ in terms of the percentage of bone, fat or muscle for any of the retail cuts. The lower meat yield, particularly in the more expensive loin and leg of the NA, when compared to the commercial meat breed (D) could make the former less preferred for meat production. However, the NA compared more favourably than the dual-purpose SAMM. Differences in carcass composition could be attributed to the fact that the NA is an unimproved and late maturing sheep breed.

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

The aim of this study was to develop and evaluate models for predicting the carcass composition of lambs. Forty male lambs were slaughtered and their carcasses were cooled for 24 hours. The subcutaneous fat thickness was measured between the 12th and 13th rib and breast bone tissue thickness was taken in the middle of the second sternebrae. Left side of carcasses was dissected and the proportions of lean meat (LMP), subcutaneous fat (SFP), intermuscular fat (IFP), kidney and knob channel fat (KCFP), and bone plus remainder (BP) were obtained. Models were fitted using the seemingly unrelated regression (SUR) estimator which is novel in this area, and compared to ordinary least squares (OLS) estimates. Models were validated using the PRESS statistic. Our results showed that SUR estimator performed better in predicting LMP and IFP than the OLS estimator. Although objective carcass classification systems could be improved by using the SUR estimator, it has never been used before for predicting carcass composition.

Myostatin allelic status interacts with level of nutrition to affect growth, composition, and myofiber characteristics of lambs1

The objective of this experiment was to determine if growth, carcass composition, and myofiber characteristics of lambs were affected by heterozygosity for a myostatin mutation (g+6723G>A) when offered differing allowances of feed administered with or without ractopamine. Heterozygote [MSTN A/G (n = 40)] and homozygote wildtype [MSTN G/G (n = 39)] castrate male lambs were individually fed ad libitum (HI; 1.8 × estimated ME(m)) or a restricted allowance (LO; 1.1 × estimated ME(m)) of a diet (191 g of CP/kg of DM and 12 MJ of ME/kg of DM), supplemented with (0.4 mg/kg of BW) or without the β-adrenergic agonist ractopamine (RAC or NO RAC) for 47 d. The lambs were scanned by computed tomography at the beginning and completion of the feeding experiment to calculate composition of lean, fat, and bone in the carcass component of the body. The MSTN A/G HI intake lambs had significantly greater total daily carcass growth (P = 0.045) and loin eye depth (P = 0.022) and tended to have a greater daily growth of lean (P = 0.09) in the carcass, compared with MSTN G/G HI intake lambs. Conversely, MSTN A/G LO intake lambs tended to have less daily lean deposition (P = 0.09), significantly less total daily carcass growth (P = 0.045), and had a greater percentage of type IIX myofibers (P < 0.01) and total myofiber area (relative area) of type IIX myofibers (P = 0.013). The inclusion of RAC increased final BW (P = 0.03) and ADG (P = 0.02), percentage of type IIC (P < 0.001) and IIA (P = 0.012) myofibers, cross-sectional area of types I (P = 0.04) and IIAX (P = 0.04) fibers, and the relative area of type IIC (P = 0.003) and IIA (P = 0.01) myofibers in the LM. The experiment demonstrated that including RAC in the diet of lambs increased final BW and ADG, but not HCW, and increased proportion of type IIC and IIA myofibers and cross-sectional area of type I and IIAX myofibers. Our data suggest that RAC and the heterozygous myostatin mutation act together to increase growth of muscle on a high plane of nutrition. The experiment also demonstrated that poor nutritional background of lambs heterozygous for the myostatin mutation may negatively influence their growth rates and myofiber characteristics.

The effects of diet, slaughter weight and docking on growth, carcass composition and meat quality of fat-tailed Barbarine lambs. A review

This review summarises the main factors that influence meat production and quality in fat-tailed Barbarine (FTB) lambs. As a general feature, FTB lamb's growth is moderate, and the average daily gain ranges between 100 and 350g. The carcass being relatively fatty, carcass fat content varies from 10% to 32%; white fat and rose meat are often dominant in these carcasses. The meat fatty acid profile of this fat-tailed breed is similar to that of thin-tailed ones, with a prevalence of palmitic, stearic and oleic acids. The order of dissected adipose tissues accumulation, estimated by allometry coefficients, is in agreement with observations in thin-tailed sheep. However, tail fat allometry coefficient is closer to kidney fat values rather than to the subcutaneous one. Concerning effects of feed level, growth of FTB lambs fed silage is higher than those fed oat hay. With moderate concentrate supply, FTB lambs' growth is more pronounced on pasture diet than on the feedlot (FL) diet. Furthermore, at similar slaughter weights, carcasses of lambs fed pasture diet have less tail and carcass fat than those from lambs fed FL diet (5% and 18% vs. 9% and 24% for grazing and FL lambs, respectively). No difference in fat colour, fat firmness or cooked meat flavour is observed between carcasses obtained at different slaughtering weight (i.e. from 25 to 35kg). The tail docking of FTB improved lambs' growth particularly before weaning. Its effect on carcass composition and fat proportion depends on stage of slaughtering and type of fattening diet. For suckled lambs (4months), the docking resulted in the lower carcass fat weight (and proportion), while for fattened lambs, carcass composition was similar for all types of lambs. Overall, FTB lambs always grow slower than Noire de Thibar lambs. This is particularly pronounced during the fattening phase. Then, for FTB breed, the possibilities to obtain heavy carcasses are at risks of fat accumulation, 22.8% vs. 14.4% for FTB and Noire de Thibar thin-tailed lambs, respectively. However, the main advantage of FTB breed is that adults are well adapted to food scarcity and may produce lambs even under harsh conditions.

Effect of coconut oil supplementation on the carcass composition and muscle physicochemical characteristics in lambs

A study was carried out with 10 male lambs of Bulgarian dairy synthetic population. The animals were divided in two groups-control and experimental as the diet of the latter was supplemented with coconut oil in amount 20g/d per animal for a period of 90 days. After finishing the experiment, complete slaughter analysis was done on the half carcasses of the animals from both groups and pH 24h, colour, water holding capacity, content of myoglobin, fat, protein, moisture and ash in m. Longissimus dorsi and m. Semimembranosus were determined. The coconut oil supplementation led to significant increase of the contents of the subcutaneous (?&lt;0.001) and intermuscular fat (?&lt;0.05) in the half carcass and its individual parts as well, and influenced significantly the colour of the muscles which was darker in the lambs of the experimental group. Specific deposition of fats in dependence on the location in the carcass was observed. The content of subcutaneous fat was lowest in the neck and highest in the loin, whereas that of intermuscular fat was lowest in the leg and highest in the shoulder of the lambs. Significantly higher water holding capacity (?&lt;0.05) in m. Longissimus dorsi and myoglobin content in m. Semimembranosus (P&lt;0.01) were observed, due to the differences in the type of the muscles.

Production and physical composition of Priangan male sheep carcass supplemented by Pasak Bumi peptide (Eurycoma longifolia Jack).

Pasak Bumi ( Eurycoma longifolia Jack/ELJ) is frequently claimmed to increase expression of masculinity, including inducing the lean growth. This study was aimed to determine the effect of ELJ peptide supplementation on yield and physical composition of lamb carcasses. Sixteen Priangan rams about 1 year old with average weight of 30.43±1.41 kg were maintained in individual cages. The experimental rams were divided into 4 treatments i.e. T0, T1, T2, and T3. In T0, T1 and T2 treatments, the experimental rams were administered: 0, 1.5, and 3 mg ELJ peptide/kg BW, respectively. In the T3 treatment, the experimental ram were administered 1 mg/kg commercial product eurypeptide ® . The ELJ peptide and commercial product were administered first in the morning prior to feeding. The experiment was conducted in a completely randomized design of four treatments and four replications. Data were covariance analyzed with an empty body weight as covariate for carcass weight and the right carcass weight as covariate for carcasses physical composition. The results showed that the weights of dissection body fat of T2 and T3 were lower than T0 (P < 0.05) and T1 (P < 0.01). Fat weight reduction was found in all parts of the carcass and more apparent in the fore saddle. Lean weights were higher ( P < 0.05) in T3 and T2 as compared to T1 and T0. The pattern of lean weight differed among treatments in the wholesale cuts that follow the total lean weight eventhough it was not significant. ELJ peptide treatment did not significantly affect either bone weight or wholesale cuts weight. In conclusion, T2 and T3 can improve carcass composition with equal ability. Key Words : Ram, Eurycoma Longifolia Peptide, Carcass

Relationship of fat-tail and body measurements with some economic important traits in fat-tail Makoei breed of Iranian sheep

This research seeks to predict in vivo carcass composition of lambs. A total of 576 Makoei fat-tailed lambs were used. Lambs were 6-7 months fold and weighed about 15.1 - 41.4 kg. Measurements included body weight, upper, middle and lower tail-depth and width, upper, middle, lower tail and neck circumference, right, middle and left tail-length, body length, whither height, abdominal and heart girth. Having slaughtered each animal, omental, mesenteric and tail fat were separated and weighed. Weight of fat-tail and sum of omental and mesenteric contents varied from 50 - 2290 g and 8.1 - 536 g, respectively. These traits showed relatively high correlation with all fat-tail and body measurements. The highest correlations were observed between fat-tail weight and lower circumference and live body weight measures (68 and 67%, respectively). Keywords : Makoei breed, fat tailed sheep, carcass composition African Journal of Biotechnology Vol. 9(36), pp. 5989-5992, 6 September, 2010

The influence of fat score and fat trimming on primal cut composition of South African lamb

The objectives of this study were to evaluate the primal cut composition of South African lamb carcasses with different fat scores, and to identify cuts suitable for fat trimming. Sixty grain fed Dorper lambs (rams and ewes) were divided into three groups and slaughtered at 30, 36 and 42 kg. Chilled carcass sides were subdivided into seven primal cuts. The cuts were dissected into meat (muscle, intermuscular and intramuscular fat), bone and subcutaneous fat (SCF) in order to determine the physical composition per cut and for the whole carcass. The % subcutaneous fat (SCF) in the loin increased the most (26 units) as the fat score increased from 1 to 5, followed by the flank, shoulder and neck. The % meat (lean) of the neck, thick rib and breast showed no significant change between fat scores 1 to 5, while % bone decreased significantly (>6% units). Meat and bone proportions decreased significantly with an increase in fat score for the loin, flank, leg and shoulder. The composition of the loin cut was most affected overall by changes in the fat score. Since different cuts accumulate SCF at different rates during fattening, trimming of SCF could reduce the boneless % SCF level of the major cuts such as the loin, leg and shoulder by 12, 6 and 9 units, respectively, when trimmed from SCF equal to a fat score 5 to a fat score 3. Further trimming to levels equal to a fat score 1, could reduce the % SCF by 18, 8 and 5 units, respectively on a boneless level. Considering differences in relative increase in intermuscular fat (IMF) and SCF in different cuts, the leg seems to be the most suitable cut for trimming in fat carcasses, since the IMF : SCF ratio is the lowest compared to the other larger cuts namely the loin and shoulder.

Effect of Permanent Hypoinsulinemia on Appetite, Performance, Carcass Composition, Blood Metabolites and Leptin Concentrations in Lambs

Insulin has crucial roles in energy metabolism in all mammals but has been less studied in ruminants. An experiment was conducted to investigate the effects of hypoinsulinemia induction on appetite, performance, carcass composition and blood metabolite levels in sheep. Treatments were intravenous injection of four doses of streptozotocin; 0, 25, 50 and 75 mg/kg BW named C, L, M and H, respectively. Twenty male lambs were divided into four treatment groups. Animals in group H could not continue the experiment because of abnormalities. The duration of the experiment was eight consecutive weeks, and injection was performed at the end of week 3. Feed and water intakes were measured weekly and weight changes of animals were recorded and used for calculation of other growth parameters. Blood samples were collected weekly via venipuncture at fasting and 2.5 h post-prandial and analyzed for hormones and blood metabolites. Results showed a marked hypoinsulinemia in group M with significant decrease in fasted and post-prandial insulin concentrations and also fasted leptin concentrations vs. the control group C (p 0.05). In conclusion, the results suggested a regulatory role of insulin in energy metabolism of ruminants by exerting two opposing effects: central catabolic and peripheral anabolic.

Effects of different levels replacement of ensiled pistachio epicarp with corn silage on fattening parameters and lamb performance

There is about 430000 hectares of pistachio garden in Iran and annual dry pistachio production is 688000 tones. There are some problems with this by-product are including: 1) deterioration in less than 24 hours so it could not stored for long term. 2) Pistachio epicarp contains high level of tannins and other phenolic compounds, and there is little information about its effects in ruminants. 3) This by-product is potentially an environmental pollutant and cost effective for disposal. A study was conducted to investigate possibility of different levels replacement of ensiled pistachio epicarp (EPE) with corn silage and its effects on growth rate and carcass composition of lambs.

Estimation of light lamb carcass composition by in vivo real-time ultrasonography at four anatomical locations1

The objectives of this study were to study the relationship between in vivo ultrasound measurements and cold carcass measurements at 4 anatomical points of the backbone, and to establish regression equations to estimate carcass composition within the cold carcass weight range for Ternasco lambs (8 to 12.5 kg) by using ultrasonic measurements taken at a single location. Measurements of subcutaneous fat and skin thickness and of muscle depth and width were taken over the 10th to 11th and 12th to 13th thoracic vertebrae and the 1st to 2nd and 3rd to 4th lumbar vertebrae. These measurements were taken at 2 and 4 cm from the nearest end of the LM to the backbone and at 1/3 of the LM width with the probe perpendicular to and parallel to the backbone. The left sides of the carcasses were dissected into muscle, fat, and bone. Body weight (22.6 kg) and cold carcass weight (10.8 kg) were representative of Ternasco light lambs. Muscle depth measured at 2 cm, 4 cm, and 1/3 of LM width remained regular, with slight ups and downs along the spine. All the pairs of in vivo ultrasound and cold carcass measurements were significantly different (P<0.05) and had small correlations. All the ultrasound measurements of muscle depth at any location or at any distance to the backbone were less than their equivalent cold carcass measurements, with differences ranging from 0.8 to 5.9 mm. Differences between ultrasound fat thickness + interface (US_FDGI) and cold carcass fat thickness were less than differences between ultrasound fat thickness and cold carcass fat thickness, ranging from -0.9 to -1.0 mm for the former and from -2.1 to -0.5 mm for the latter. The small differences in absolute values between US_FDGI and cold carcass fat thickness suggest that US_FDGI is the best measure of the real fatness level of the lambs. The best prediction equations for muscle, bone, and fat were developed with in vivo ultrasound data measured at the 1st to 2nd lumbar vertebrae perpendicularly to the backbone, but they had limited predictive value. To predict the muscle content of carcass, BW and muscle depth were included, and they explained 59% of variation. Fifty-one percent of total fat was predicted by BW and fat thickness, whereas only 17% of the variation in bone was predicted by 2 fat-related variables. The BW of lambs was an important predictor to improve regression equations but ultrasound measurements were the most important variables when a narrow range of BW was used.

Prediction of lamb carcass composition and meat quality using combinations of post-mortem measurements

Various post-mortem measurements (carcass weights, conformation and fatness classes, external carcass dimensions, eye muscle dimensions, subcutaneous fat depth, pH and temperature) were recorded on 197 Texel (TEX) and 200 Scottish Blackface (SBF) lamb carcasses. The potential use of these measurements to predict carcass composition and key meat quality traits was investigated, to enable categorisation of carcasses in the abattoir and/or for use in genetic improvement programmes. By combining different measurements, accurate predictions of dissected carcass muscle weight (adjusted R 2 0.93 in TEX, 0.88 in SBF) and fat weight (adjusted R 2 0.84 in TEX, 0.87 in SBF) were achieved, and moderate predictions of intra-muscular fat (adjusted R 2 0.56 in TEX, 0.48 in SBF), whilst shear force was predicted with low to moderate accuracy (adjusted R 2 < 0.33 across breeds and cuts). Sex, eye muscle dimensions and subcutaneous fat depth improved predictions of carcass composition and intra-muscular fat, whilst pH or temperature provided little additional benefit for these traits, but increased prediction accuracies for shear force. These results could contribute to the development of automated carcass grading systems or help inform breeding decisions.

Prediction of fat, muscle and value in Norwegian lamb carcasses using EUROP classification, carcass shape and length measurements, visible light reflectance and computer tomography (CT)

One hundred and twenty carcasses were sampled to compare different techniques or methods for prediction of lamb carcass composition and value. Four methods that are used at the Norwegian Meat Research Centre, Animalia, were selected. These were the basic EUROP classification, the advanced EUROP classification using carcass shape and length measurements, visible light reflectance probing (GP) and Computer Tomography (CT). The different technologies were tested using an iterative approach, selecting calibration and validation data sets from the 120 carcasses randomly, where 90 carcasses were used for calibration, and 30 for validation. The best prediction models were obtained using CT, with respect to prediction error and correlation between predicted and measured value of carcass fat and muscle (in kg), and value (in NOK). Due to high cost and low operating speeds of CT, optical probing (GP) may be the second best solution of the technologies used in this study, combined with a CT dissection reference as an alternative to manual dissection.

Effects of feeding system on carcass and non-carcass composition of Churra Tensina light lambs

Thirty-eight single male lambs (3.6 ± 0.08 kg live weight at birth) were used to study the influence of feeding system on carcass and non-carcass composition of Churra Tensina light lambs. Treatments: indoor (IND), lambs housed indoors consuming concentrate ad libitum until weaning at 53 days of age, and ewes grazing 8 h a day without their offspring and receiving a supplement of barley meal after grazing; grazing (GR), ewes and lambs grazed continuously without concentrate and lambs were unweaned. When lambs reached 22–24 kg live weight they were slaughtered. Carcass and non-carcass composition was recorded. GR lambs displayed higher carcass shrink ( P < 0.05) and lower dressing percentage ( P < 0.01) than concentrate-fed lambs. IND lambs had more body fat mainly due to the heavier kidney ( P < 0.001) and subcutaneous ( P < 0.001) fat depots. Total non-carcass weight was not affected by treatment ( P > 0.05), but red organ (heart, lung and trachea, thymus, liver, spleen, kidney, diaphragm, pancreas, gall bladder, bladder, and testicles and penis), digestive tract (stomach, small intestine and large intestine) and head, skin, and feet (HSF) weights differed between treatments ( P < 0.05). IND lambs had heavier red organs and HSF ( P < 0.05) although this difference disappeared when expressed as a percentage of empty body weight. Small intestine weight in grazing lambs was heavier ( P < 0.001) and, consequently, the total digestive tract differed similarly ( P < 0.01). Treatment influenced the weights ( P < 0.05) of all joints except leg ( P > 0.05), showing heavier joints for IND carcasses. The feeding system had a greater effect on subcutaneous fat ( P < 0.001) than on intermuscular fat ( P < 0.05) in most of the standardized joints. IND carcasses produced a greater proportion of muscle/bone in all joints, except neck, whereas GR produced a greater proportion of muscle/total fat due to the lower amount of fat recorded in this treatment. The percentage of fatty acids was not affected by treatment ( P > 0.05) although the percentage of C18:3 was greater and the ratio of C18:2/C18:3 was lower in grazing-fed lambs. The absence of any effect of treatment on the fatty acid percentages may be influenced by the short raising period and by the similar amount of intramuscular fat in both treatments. It is concluded that light lambs reared under grazing conditions can produce carcasses of acceptable quality, due to the lower percentage of subcutaneous fat, but with a similar intramuscular fat content.