Severiano Silva

Carcass composition and meat quality of equally mature kids and lambs.

The interaction between sarcomere length and postmortem proteolysis as related to meat tenderness is not clear. The extent of thick and thin filament overlap alters actomyosin binding and may alter substrate availability during aging-induced tenderization. The objective of this study was to determine the influence of sarcomere length on proteolytic degradation in beef. Strips from bovine semitendinosus were either stretched 40% and restrained or allowed to shorten unrestrained in an ice bath. After rigor completion, 0.6-cm cross sections were fabricated and were randomly assigned to 2, 4, 7, or 10 d of aging treatments. Myofibrils were isolated for sarcomere length determination. Samples were collected and frozen for shear force analysis, and muscle proteins were extracted for SDS-PAGE and Western blotting analyses to determine troponin T (TnT) proteolysis. Sarcomere length was greater (P < 0.01) in stretched muscle samples compared with shortened samples (2.57 vs. 1.43 microm, respectively). Correspondingly, shear force values were greater (P < 0.05) in shortened samples than stretched samples. Western blots revealed the presence of 3 major intact TnT bands that diminished with time postmortem and 4 bands (TnT degradation products) that accumulated during postmortem storage. Quantification of intact TnT showed increased (P < 0.05) proteolysis at 4 and 7 d postmortem in samples with long sarcomeres. By 10 d, only traces of the greatest molecular weight intact TnT band were evident in both shortened and stretched samples, suggesting this TnT band may be more susceptible to proteolysis than other intact TnT bands. Degradation products of TnT appeared earlier postmortem in samples with long sarcomeres. The 30-kDa TnT fragment appeared after 7 d of postmortem storage in samples with long sarcomeres but not until 10 d in muscle containing short sarcomeres. Collectively, these data show that postmortem TnT proteolysis is sarcomere length-dependent and suggest that thick and thin filament overlap may influence the postmortem aging process in beef.

Sheep carcass composition estimated from Longissimus thoracis et lumborum muscle volume measured by in vivo real-time ultrasonography

The use of Longissimus thoracis et lumborum muscle (LM) volume measured in vivo by real-time ultrasonography (RTU) to estimate carcass composition was evaluated in 47 female sheep. Animals were scanned over six sites (7th, 9th, 11th and 13th thoracic vertebrae and 2nd and 4th lumbar vertebrae). After slaughter carcass weight (CW) and composition by dissection were determined. RTU volume measurements were calculated by multiplying the LM area at each site by the vertebra lengths. Equivalent measurements to those taken in vivo were obtained on the carcass using a digital camera and image analysis. The correlation between LM volume measured by RTU and in the carcass was high for all scans. LM volume was better in predicting carcass muscle than carcass fat. Lower determination coefficients were obtained between LM volume and carcass tissues expressed in % of CW. The best estimates of carcass tissues weights and proportions were obtained using the LM volume between the 2nd and the 4th lumbar vertebrae for all tissues. Multiple regression equations were fitted using live weight (LW) and LM volume to predict carcass composition. For all tissues, the best fit was obtained with two, three or four independent variables and the stepwise procedure was consistent in selecting LW to establish the prediction equations. Weights and proportions of muscle, subcutaneous fat, intermuscular fat and total fat were accurately predicted. These results indicate that Longissimus thoracis et lumborum muscle volume measured in vivo by RTU can be used to predict sheep carcass composition (muscle and fat).

Relationship between ultrasound measurements of body fat reserves and body condition score in female donkeys.

Several methods have been developed to monitor body fat reserves of farm animals and body condition scoring (BCS) is generally assumed to be the most practical. Objective methods, such as real time ultrasonography (RTU), are accepted methods for measuring fat reserves in several farm species but there is no published information about the use of RTU to monitor body fat reserves in donkeys. The aim of the present study was to determine the relationship between RTU measurements and BCS in female donkeys (jennies) (n=16) with a BCS of 3-7 on a 9 point scale. Ultrasound images were captured using an Aloka 500-V scanner equipped with a 7.5 MHz probe and subcutaneous fat (SF, range: 1.0-14.0mm) and thoracic wall tissue (TD, range: 5.6-21.4mm) depths measurements were determined. A significant correlation was found between BCS and all RTU measurements (0.65<r<0.86; P<0.01). Linear regression models described the relationships between RTU measurements and BCS and between log transformed RTU measurements and log transformed BCS. All equations with variables transformed into a logarithmic scale gave better coefficients of determination (0.42<r(2)<0.75) and an increase of 7-23% in this coefficient. The study suggested that RTU depth measurements have a logarithmic relationship with BCS and that RTU combined with image analysis permits accurate fat and tissue depths measurements to monitor fat reserves in jennies.

Muscle fiber type characterization and myosin heavy chain (MyHC) isoform expression in Mediterranean buffaloes

This study aimed to evaluate myosin heavy chain (MyHC) isoform expression and muscle fiber types of Longissimus dorsi (LD) and Semitendinosus (ST) in Mediterranean buffaloes and possible fibers muscles modulation according to different slaughter weights. The presence of MyHC IIb isoforms was not found. Only three isoforms of MyHC (IIa, IIx/d and I) were observed and their percentages did not vary significantly among slaughter weights. The confirmation of the presence of hybrid muscles fibers (IIA/X) in LD and ST muscles necessitated classifying the fiber types into fast and slow according to their contractile activity, by m-ATPase assay. For both muscles, the muscle fiber frequency was higher for fast than for slow fibers in all weight groups. There was a difference (P<0.05) in the frequency of LD and ST muscle fiber types according to slaughter weights, which demonstrate that the slaughter weight influences the profile of muscle fibers from buffaloes.

The value of in vivo real time ultrasonography in assessing loin muscularity and carcass composition of rabbits

Sixty nine growing rabbits were scanned over the lumbar region using a real time ultrasonography (RTU) machine to estimate loin muscularity and carcass composition. Longissimus thoracis et lumborum muscle (LM) depth, width and area were taken. Animals were weighed (LW), slaughtered and carcass composition was determined. Equivalent measurements to those taken by RTU in vivo were taken on the carcass and muscularity indices were calculated on carcass and in vivo. Simple correlations between the two types of measurements were determined and carcass composition was estimated by simple and multiple regressions. The LW varied from 1200 to 3410g. The simple correlations between carcass and in vivo RTU LM measurements were high (P<0.001) and the LM area was the trait with the highest correlation (r=0.92). Simple correlations between muscularity indices measured by RTU and in carcass were significant (P<0.001). In vivo RTU measurements explained a large amount of the variation of the carcass meat weight (MW) and bone weight (r(2) range from 0.49 to 0.77; P<0.001). Using multiple regression equations to estimate carcass composition, the best fit was obtained with the LW and one or more in vivo RTU measurement. The LW explained 90.6% of the variation of MW in the carcass. In vivo RTU is able to estimate loin muscularity and carcass composition of rabbits with accuracy. The usefulness of in vivo RTU and LW to predict carcass composition of rabbits using multiple regressions was also shown.

Prediction of carcase and breast weights and yields in broiler chickens using breast volume determined in vivo by real-time ultrasonic measurement.

1. The use of in vivo real-time ultrasonic (RTU) to predict breast and carcase weights and yields in 103 male broiler chickens was evaluated. Breast area (mm2), thickness (mm) and volume (cm3) were measured by RTU in three identified sites. After RTU measurements, the broiler chickens were weighed (live weight, LW, g) and slaughtered. Carcase and breast weights (g) and physical measures of breast area (mm2), and thickness (mm) corresponding to the three identified sites, and volume (cm3) were recorded. 2. The best simple correlation between RTU and carcase measurements was obtained for breast volume. Breast and carcase weights were well predicted by LW. Furthermore, breast volume measured in carcase or by RTU was better in predicting breast weight and breast and carcase yields. 3. Multiple regression equations were fitted using LW (g) and RTU measurement of breast volume to predict breast and carcase weights and yields. The coefficients of determination were 0·52 and 0·65 for breast and carcase yields, respectively, and 0·92 and 0·99 for breast and carcase weights, respectively.

Relationship between body condition and neck crest score systems and subcutaneous fat, tissue and muscle ultrasonic measurements in horses

The aim of the present study was to determine the relationship between real time ultrasonography (RTU) fat, muscle and thoracic wall tissue thickness measurements and both body condition score (BCS) and cresty neck score (CNS). The subcutaneous fat depth at lumbar (SFL) and rump, the tissue depth over (TDoR) and between the 12th and 13th ribs and longissimus thoracis et lumborum muscle depth were measured by RTU in forty two horses. The relationship between BCS, CNS and RTU measurements shows that the best correlation with BCS was achieved with TDoR (r = 0.70; P < 0.01) and for CNS was obtained with SFL (r = 0.50; P < 0.01). Also it was observed that best regression of BCS on RTU measurements was achieved with a polynomial model with TDoR (R2 = 0.599; P < 0.01). Further research is needed to improve RTU image capture and analysis for application in horse body fat reserves management.

Fuzzy based subcutaneous fat assessment in real time ultrasound images

The present work addresses the study of techniques of digital image processing based on fuzzy logic for subcutaneous fat (SF) estimation in real time ultrasound (RTU) images. The process for SF automatic estimation in RTU images is divided into two steps: the identification of the image area corresponding to the SF regions and, from these regions, the SF estimation. In order to deal with the ambiguity present in the gray levels of RTU images, fuzzy logic based methods are used. Experimental results are also presented.

Effects of seasonal variation, group size and sex on the activity budget and diet composition of the addax antelope

Behaviour and diet composition are critical elements in conservation biology within the scope of reintroduction programs. Here we focused on addax (Addax nasomaculatus), a Critically Endangered antelope species, in the Jbil National Park, Tunisia. In this study, we advanced the hypothesis that season, day period, sex and social structure have an effect on the activity budgets and diet composition of addax. Three groups were selected (large group, adult pair and solitary male). Resting, moving, grazing, vigilance and other behaviours were recorded during two seasons (dry and wet) and in the morning and the afternoon. In addition, faecal samples were collected. The results indicate that season and day period were the main factors affecting the activity budgets. The resting behaviour increased from the wet to the dry season, and from morning to afternoon. The grazing and moving behaviours increased during the wet season and decreased from morning to afternoon. Addax select a mixed diet composed of perennial and herbaceous plant species notably during the wet season. In addition, we observed that addax modify their behaviour according to the season and forage availability. This represents an adaptive strategy to survive in a desert climate with a stochastic low-resource environment and depending on ambient climatic conditions.

Estimation of carcase composition of goat kids from joint dissection and conformation measurements

Abstract The aim of this study was to develop equations to estimate percentages and carcase tissue weights of suckling goat kids by using cold carcase weight (CCW), carcase conformation measurements and joints tissue as independent variables. Carcases dissection data from 55 goat kids were used for regression analysis. Leg and shoulder muscle weight showed the highest positive correlations with carcase muscle weight (r = .98). Shoulder tissue weight showed the highest correlation with carcase bone weight (r = .97), carcase subcutaneous fat weight (r = .95) and carcase intermuscular fat weight (r = .95). Also, shoulder tissue percentage showed the highest correlation with carcase muscle percentage (r = .93) and carcase subcutaneous fat percentage (r = .90). CCW explained 95.9% of muscle weight carcase variability. The percentage of the variation explained in other tissues (bone, subcutaneous and intermuscular fat) was lower, but not negligible (89.6%, 60.7% and 48.7%, respectively). Chest circumference and carcase compactness presented the highest correlation with weight of carcase tissues, especially with muscle weight (r = .93), bone weight (r = .93 and .89, respectively), subcutaneous fat (r = .71 and .79) and intermuscular fat weight (r = .68 and .67). The results of this study support the conclusion that the shoulder tissue composition allows accurate estimation of the carcase composition. Also, CCW, chest circumference and carcase compactness measurements were good predictors of the weight of carcase tissues in goat kids, with the advantage to be non-destructive and easy to obtain.