In vivo estimation of goat carcass composition and body fat partition by real-time ultrasonography.

The accuracy of ultrasound measurements to assess goat carcass composition and the partition of body fat depots was evaluated. An ultrasound machine with a 5-MHz probe and image analysis was used to assess in vivo fat thickness and muscle depth in 56 Spanish Celtiberica adult goats, in lumbar and breast body regions. The goats were slaughtered and the weight of body fat depots recorded. Measurements corresponding to the in vivo ultrasound fat thickness and muscle depth were taken on carcasses. The left sides of carcasses were completely dissected into their components. The best relationships (r = 0.94, P < 0.01) between in vivo and carcass measurements of fat thickness were obtained when measurements were taken at the sternum, and the best anatomical point was located between the third and fourth sternebrae. The best correlation coefficients (r = 0.84) for muscle depth were found for measurements taken between the third and the fourth lumbar vertebrae at 2 cm from the middle of the vertebral column. Body weight and ultrasound measurements were used to fit the best multiple regression equations to predict carcass composition and the partition of body fat depots. All equations, with the exception of those for muscle quantity, omental, and total body fat depot amounts, were computed after performing a logarithmic transformation. Body weight in association with the ultrasound measurement taken at largest LM muscle depth, between the first and second lumbar vertebrae accounted for 90% of the muscle weight. Body weight was the first variable admitted into the prediction models of muscle, mesenteric fat, and total body fat and accounted for 82, 67, and 79% of the variation in tissue weights, respectively. The ultrasound measurement of fat thickness taken at the third sternebra was the first variable admitted into the prediction models for intermuscular fat, kidney and pelvic fat, and total carcass fat and accounted for by 73, 75, 71, and 79% of the variation in the weight of these fat depots, respectively. The ultrasound measurements taken in the breast region, particularly at the third and fourth sternebrae, were the most suitable for assessing fat thickness. The results of this experiment suggest that BW associated with some in vivo ultrasonic fat measurements allow the accurate prediction of goat carcass composition and body fat depots.

In vivo estimation of lamb carcass composition by real-time ultrasonography.

The objective of this study was to evaluate the accuracy of ultrasonography to measure fat thickness in live lambs and predict carcass composition to find a system that can assess carcass composition easily and accurately, without damage to the product and can improve carcass classification. Fat thickness (FTh) between the 12th and 13th ribs and between the 3rd and 4th lumbar vertebrae, was measured in vivo using real-time ultrasound, in 67 Churra Galega Bragançana males (mean weight 36.0kg, range 21.5-47.0kg), using an ALOKA SSD-500V equipped with two probes (5 and 7.5MHz) in order to predict carcass composition. The most satisfactory correlation between carcass and ultrasound measurements was between the 3rd and 4th lumbar vertebrae fat thickness (FTh). The first variable admitted in the models to predict carcass composition (live weight, LW) explained between 63% and 96% of the total variation of the weight of the components of the carcass. In fact, 96% of the variation in total amount of muscle was accounted for by live weight. The inclusion of the ultrasound measures with the 7.5MHz probe improved, in all prediction equations, the coefficient of determination (R(2)) with a substantial reduction in the residual standard deviation (RSD). In relation to the subcutaneous fat of the carcass, 85% of the variation was explained by live weight and the FTh 12-13 7.5 measurement. In the prediction model for total carcass fat weight, live weight and ultrasound fat thickness measurement explained 88% of the variation. The results indicate that in vivo ultrasound fat thickness measures in association with live weight can be used to predict carcass composition in Churra Galega Bragançana lambs.

Lamb meat quality of two breeds with protected origin designation. Influence of breed, sex and live weight.

Lamb meat quality of two Portuguese products was examined. The influences of slaughter weight, sex and breed on eating quality were evaluated. Data were obtained from 72 lambs of two different breeds with protected designation origin. In accord with the normal slaughter weight in the region three classes were considered: A: 9-14kg live weight; B: 14-19kg live weight and C: 19-24kg live weight. pH of M. longissimus thoracis et lumborum muscle (MTL) was measured 1h and 24h after slaughter. Meat colour was estimated in the M. longissimus thoracis et lumborum muscle (MTL) muscle on the 12th rib using the L*a*b* system. Shear force was evaluated 72h after slaughter. Sensorial analysis was assessed by a trained taste panel of 12 members. The pH values found could be considered within the normal pH range, between 5.5 and 5.9. When the pH measurement was made 24h after slaughter, the heavy lambs had significant higher value than the light lambs. In relation to colour variables, live weight, sex and breed had no effect on the red index (a*). Lightness (L) decreased with increasing live weight and the light lambs had higher yellow index (b*) than the heavier lambs. Shear force increased with live weight and the Bragançano breed had a greater mean shear force than the Mirandesa (7.8 vs. 6.8kg/cm(2)). The heavy carcasses had more flavour intensity than the light ones. Mirandesa lambs had significantly lower values for toughness, stringy and odour intensity than Bragançana lambs.

Breed, slaughter weight and ageing time effects on physico-chemical characteristics of lamb meat.

The effects of breed, slaughter weight and ageing time on the meat quality of the three most important Spanish breeds were considered. Two hundred and twenty-five lambs of Rasa Aragonesa-local meat breed-, Churra-local dairy breed- and Spanish Merino were used. Animals (75 of each breed) were slaughtered at three different live weights (10-12, 20-22 or 30-32 kg), and the meat was aged for 1, 2, 4, 8 or 16 days. The meat pH, colour, amount of haem pigments, intramuscular fat, moisture, hydroxyproline content and sarcomere length were measured at 24 h post-mortem. Meat texture was measured by compression after each ageing time. The pH of the samples ranged from 5.50 to 5.58. Meat colour varied with breed and slaughter weight (P⩽0.01), the M. longissimus thoracis was lighter in the youngest animals and in the Churra breed and redder in Merinos. Intramuscular fat increased and moisture decreased for heavier lambs. Differences in collagen were associated with breed (P⩽0.01); total and insoluble collagen contents were higher in the Churra breed. Sarcomere length was only slightly affected by slaughter weight. Meat from the Churra breed had the highest values at high levels of compression. Suckling lambs (10-12 kg) had greater myofibrillar toughness than heavier lambs and ageing strongly influenced myofibrillar tenderness.

Effect of level of feed intake on the development of gastrointestinal parasitism in growing lambs.

A study was conducted to examine the role of nutrition in the development of gastrointestinal (GI) parasitism, performance and pathophysiology of parasitism in female lambs. Forty-four months old ewe lambs received for 6 weeks 0, 1500 or 7000 L(3) larvae of Teladorsagia circumcincta in two doses per week. The animals were given access to a pelleted diet to meet energy requirements for gaining weight close to their potential (H) or approximately 50% of it (L). The level of protein in the diet was 20-30% above requirements for both planes of nutrition. Measurements of body weight, serum pepsinogen concentration and faecal egg counts were taken at weekly intervals. All animals were slaughtered 2 weeks after the last larval dosing for estimation of worm count, carcass composition and reproductive tract development. Voluntary intake of infected animals decreased by approximately 10%. Both nutrition and infection influenced lamb performance and carcass composition. However, no direct effects on reproductive tract parameters due to the presence of infection were observed. The level of L(3) infection showed a significant effect not only on faecal egg counts and on worm burden, as it could be expected, but also on the proportion of females to males, which increased significantly with the level of infection. While the plane of nutrition did not show a significant effect on faecal egg counts or on worm burden, surprisingly, both female worm size and their fecundity decreased significantly with the level of nutrition. This response was accompanied by a significant increase in the concentration of circulating eosinophils suggesting that the immune response of lambs consuming high levels of energy was enhanced compared to that of lambs kept on a restricted diet. Results herein show that in young female lambs fed on adequate levels of protein, an improvement in energy supply does not only improve carcass characteristics but clearly enhances the development of resistance to GI nematodes infection. This may have decisive management implications for the control of parasitic infections in sustainable production systems.

Carcass and meat quality in light lambs from different fat classes in the EU carcass classification system.

Ninety commercial lamb carcasses were analysed according to the four different fat classes in the light lamb European classification system. Shoulder fat increased 3%, muscle decreased 2% and bone decreased 1% for each class increase. No significant differences were found among fat classes regarding pH, WHC, cooking losses, juiciness, myoglobin content, meat colour measured immediately after cutting (L*, a*, b*), odour intensity or flavour quality. Some differences were found in colour evolution through ageing. Shear force decreased and tenderness and flavour intensity increased with fat class but this effect was only significant in the leanest animals.