PREDICTING PORK CARCASS AND PRIMAL LEAN CONTENT FROM ELECTROMAGNETIC SCANS

Fifty-four whole, pre-rigor, eviscerated carcasses (74.1±kg) wereselected over a 5-week period to represent carcasses marketedto a Northwest Iowa packing plant during the fall season.Carcasses (spanning 40.7–65.2% carcass lean) wereelectromagnetically (EM) scanned before entering the chiller.Carcass right sides were fabricated and weights were recordedfor each jowl, ham, loin, Boston butt, picnic shoulder, neckbone,sparerib, and belly. Each component was skinned and dissectedinto external fat, internal (seam) fat, bone, and lean withcorresponding weights recorded. Regression equations werederived from points and areas taken from the EM scan curve.The best 5-variable equations were developed for total carcasslean (R2=0.9502; RMSE=1.31 kg), percentage carcass lean(R2=0.8789; RMSE=1.88%), ham lean (R2=0.8475;RMSE=0.755 kg), loin lean (R2=.8511; RMSE=0.781 kg), Bostonbutt lean (R2=.7251; RMSE=0.505 kg), picnic lean (R2=0.7387;RMSE=0.464 kg), and commodity, component carcass value(R2=0.9458; RMSE= 3.24).

A NOVEL APPROACH TO GRADING PORK CARCASSES: COMPUTER VISION AND ULTRASOUND

A Computer Vision System prototype for grading pork carcasses wasdeveloped at the Lacombe Research System. The system consists oftwo components: ultrasound imaging to scan a cross-section of the loinmuscle and video imaging to capture two-dimensional (2D) and three-dimensional (3D) images of the carcass. For each of the 241 carcasses(114 barrows and 127 gilts), saleable meat yield was determined from afull cut-out. Linear, two- and three-dimensional, angular and curvaturemeasurements and carcass volume were derived from each image.Muscle area and fat thickness (7 cm off the mid-line) measured byultrasound at the next to last rib site, together with 2D and 3Dmeasurements provided the most accurate model for estimatingsaleable meat yield (R2=0.82 and RSD=1.68). Models incorporating fatthickness and muscle depth measured at the Canadian grading site(3/4 last rib, 7 cm off the mid-line) with the Destron PG-100 probe, hadthe lowest R2 and highest residual standard deviation (RSD) values(R2=0.66 and RSD=2.15). Cross-validation demonstrated the reliabilityand stability of the models; hence conferring them good industryapplicability. The Lacombe Computer Vision System prototype appearsto offer a marked improvement over probes currently used by theCanadian pork industry.

LINEAR FAT MEASUREMENTS TO PREDICT PIG CARCASS COMPOSITION

The objective of the study was to assess whether linear fat measurementdevices used currently in the South African Pig industry, still adequatelypredict carcass composition. Fat measurements were taken with theHennessy Grading Probe® (HGP), Intrascope® (INT) and Renco lean-meater® (RLM), on eighty one individually reared modern commercialpigs ranging from 60.6 -188.9 kg live weight. RLM measurements weretaken on live animals between the 2nd and 3rd thoracic vertebrae(T2/3) 45mm from the split line (P1). INT (X1) fat measurements andHGP (X1) fat and (X2) muscle measurements were taken on warm andcold carcasses between the 2nd and 3rd thoracic vertebrae (T2/3), the5th and 6th lumbar vertebrae (L5/6) and the 3rd and 4th lumbarvertebrae (L3/4), 45mm from the split line. Cold carcass weights wererecorded. Carcass sides were fully dissected and percentage lean, fat,bone and skin were calculated. Forward selection stepwise regressionanalysis was performed on all the data. In terms of adjusted R-squarevalues HGP obtained the highest level of accuracy (R2 = 0.698)followed by INT (R2 = 0.688) and then RLM (R2 = 0.577). All threedevices predicted carcass composition adequately. Overall the sitebetween the 2nd and 3rd thoracic vertebrae (T2/3) and measurementson warm carcasses predicted carcass composition the best.

PREDICTION OF THE CHEMICAL COMPOSITION OF MUTTON WITH NEAR INFRARED REFLECTANCE

SPECTROSCOPYNear infrared reflectance spectroscopy (NIRS) was evaluated as a tool to

predict the chemical composition of freeze-dried mutton. Samples usedfor the ash, dry matter (DM), crude protein (CP) and fat calibrationsconsisted of M. longissimus dorsi (eye muscle) from 19-month-oldMerino sheep, while mineral calibrations were developed with M.semimembranosus from Merino crossbreed lambs slaughtered at a liveweight of 40 kg. Samples were minced, freeze-dried and analysedaccording to standard laboratory procedures. Samples were scanned(1100–2500 nm) and partial least-squares regression (PLSR) was usedto predict the chemical and mineral composition. Multiple correlationcoefficients (r) and standard error of performance (SEP) for chemicalcomposition constituents were: ash (0.97; 0.15%), DM (0.96; 0.38%),CP (1.00; 0.92%) and fat (1.00; 0.43%), respectively. K, P, Na, Mg, Feand Zn showed acceptable SEP values of 600, 900, 77.89, 40, 3.15and 3.59 mg/kg, respectively. The r values ranged from 0.86 for Zn andK to 0.92 for Mg. Very low r values (0.26–0.49) were obtained for Cu, B,Mn, Ca and Al. It was concluded that NIRS could be used as a rapidtool for predicting proximate chemical composition and certain mineralsin freeze-dried mutton.

METHODS OF PREDICTING LAMB CARCASS COMPOSITION: A REVIEW

Methods presently available for the prediction of body and carcasscomposition in lambs were reviewed in terms of cost, speed, precisionand current usage. In vivo methods reviewed included liveweight,linear measurements, ultrasound, X-ray computed tomography (CT)and nuclear magnetic resonance (NMR)/magnetic resonance imaging.Methods reviewed for predicting composition of carcasses includedsubjective measurements, carcass weight, specific gravity, dressingpercentage, linear measurements, optical probes, video imageanalysis (VIA), total body electrical conductivity (TOBEC) andbioelectrical impedance. All methods were not directly comparable asfew studies have used multiple methods for prediction of body orcarcass composition. Limited comparisons were possible through theresidual standard deviations (RSD) published for the various methods.Although subjective methods for predicting body and carcasscompositions are rapid and relatively inexpensive, the sheep industryshould adopt objective methods in order to more readily change lambcarcass composition to meet consumer demand.

VALORACIÓN SUBJETIVA DE LA CANAL

CLASIFICACIÓN DE LA CANAL

VALORACIÓN SUBJETIVA DE LA CANAL: clasificación de la canal

Los caracteres más importantes y con mayorrelación con la composición de la canal sonla CONFORMACIÓN y el GRADO DEENGRASAMIENTO SUBCUTÁNEO DE LACANAL

Además, se considera el COLOR DELMÚSCULO Y DE LA GRASA

LA CONFORMACIÓN ESBUENA PREDICTORA DELAS CARACTERÍSTICASDE LA CANAL Y DE LACARNE?

LA CONFORMATION BOUCHERE DES AGNEAUX.La conformation des carcasses est considérée par les différents acteurs de la

filière ovine comme un critère important de la qualité. La grille de paiement desanimaux se fonde en partie sur ce critère d'évaluation visuel. Cependant, cecritère est souvent sujet à controverse d'une part à cause de sa relativesubjectivité, d'autre part à cause de la faiblesse de sa valeur prédictive pour lerendement en muscle. Les objectifs de cet article sont de présenter desrésultats sur la signification biologique de la conformation et d'évaluer le degréde fiabilité de la mesure globale de conformation notamment pour l'améliorationgénétique des qualités bouchères. Ce travail est une synthèse des résultatsobtenus dans trois études indépendantes, fondées chacune sur la comparaisonde deux types génétiques, l'un avec une bonne conformation, l'autre avec uneconformation médiocre. La conformation est le reflet de la morphologiemusculaire, plus particulièrement de l'épaisseur des muscles. L'augmentationd'épaisseur des muscles individuels est différentielle selon leur situationanatomique. L'amélioration de la conformation correspond à une augmentationdu rendement de carcasse et du rendement musculaire. Le rapport du poids demuscle sur le poids d'os est augmenté. Cela correspond à une diminution dupourcentage d'os et parfois à une augmentation du pourcentage de muscle. Leplus souvent les muscles individuels ont une répartition pondérale différentiellesur les segments de carcasse. L'adiposité n'augmente pas avec laconformation. L'augmentation des épaisseurs musculaires s'accompagne d'unglissement des caractéristiques contractiles vers des isoformes de myosine detype rapide. Enfin, ces études ont montré que certains caractères biologiquessont davantage des caractères raciaux que la conséquence d'une différence deconformation.