Dissertations / Theses on the topic 'Qualité de la carcasse'

La production de viande à partir de jeunes bovins croisés issus du troupeau laitier est fréquente en Suisse, moins en France. Pour optimiser les performances de ces systèmes de production, un suivi fin de la composition corporelle est possible à partir d’imagerie en trois-dimensions (3D) chez l’animal vivant et d’absorptiométrie bi-photonique à rayons X (DXA) pour la carcasse. Non-invasives et prometteuses, leur précision reste toutefois à déterminer. Les compositions chimique (n = 142) et tissulaire (n = 30) du corps vide et de la carcasse de bovins de race pure (n = 22 Simmental) ou croisés (n = 120 ; mère : Brune de Suisse et père : Angus, Simmental ou Limousin) ont été déterminées. Des relations ont été établies entre ces compositions et les données d’imagerie (3D et DXA) ou de dissections de la 11ème côte, par régressions linéaires multiples ou moindres carrés partiels.L’imagerie 3D in vivo a permis d’estimer la composition chimique du corps vide et de la carcasse (R2 = 0,95 ; erreurs de prédiction (RMSEP) = 7 kg). La précision pour la composition de la carcasse était meilleure à partir d’un scan DXA d’une demi-carcasse et légèrement réduite avec un scan de la 11ème côte (R2 = 0,95 ; RMSEP = 2 kg), ce dernier alliant praticité et gain de temps. Les modèles établis étaient dépendants du croisement sauf s’ils étaient établis à partir du scan DXA de la demi-carcasse. Les méthodes d’imagerie 3D et DXA permettent l’estimation fine et le suivi de la composition corporelle des bovins. Elles pourront, après automatisation, trouver des applications d’intérêt en élevage et en abattoir (classification des carcasses)
Meat production from beef-on-dairy crossbred cattle is common in Switzerland and of growing interest in France. In order to optimize those production systems performances, a fine monitoring of body composition is possible thanks to three-dimensional (3D) imaging on living cattle and dual-energy X-ray absorptiometry (DXA) for the carcass. Non-invasive and high-throughput methods, their precision still needs to be determined. Empty body and carcass chemical (n = 142) and tissue (n = 30) compositions of purebred (n = 22 Simmental) or crossbred (n = 120; dam: Swiss Brown and sire: Angus, Simmental or Limousin) cattle were determined together with 3D and DXA measurements. Relationships were established between body and carcass reference compositions and estimative variates from 3D and DXA imaging, or 11th rib dissection using multiple linear or partial least squares regressions.The 3D imaging provided precise estimates of empty body and carcass chemical compositions (R2 = 0.95; prediction errors (RMSEP) = 7 kg). Precision for carcass composition was the highest from a half-carcass DXA scan, and slightly decreased with 11th rib scan (R2 = 0.95; RMSEP = 2 kg). Nevertheless, this approach is convenient and time saving. Except for half-carcass DXA scan, most equations were affected by breed. The 3D and DXA imaging methods are of interest for the fine estimation and monitoring of the body and carcass compositions of beef cattle. After automation of the measurements, they will find applications for precision livestock farming and carcass classification in slaughterhouses

Les objectifs du projet de thèse étaient: 1) d'apporter des connaissances sur le potentiel boucher et les qualités de la viande du cabri Créole, 2) de déterminer les principales conditions d'élevage et d'abattage qui influencent le potentiel boucher et les qualités de la viande. Concernant ce deuxième point le système d'alimentation et l'âge/poids d'abattage des animaux ont été les 2 principaux facteurs de variation. Deux essais ont été conduits. Le premier a mobilisé 91 chevreaux selon un dispositif factoriel 2x3 qui a permis de tester l'effet d'herbe seule versus une ration mixte (50 %) de concentré à 3 âges d'abattage: 7, 11 et 15 mois. Le deuxième essai a mobilisé 40 chevreaux alimentés recevant une ration composée d'herbe avec 0, 140, 240 ou 340 g/j d'un concentré commercial. Le principal résultat du travail de la thèse est qu'il est possible d'améliorer la vitesse de croissance (jusqu'à 85 g/j), le poids (jusqu'à 12 kg) la conformation des carcasses (jusqu'à 4 sur une note de 5) et la qualité la viande du caprin Créole au moyen de l'alimentation. L'alimentation à base d'herbe seule et les rations mixtes permettent potentiellement d'obtenir des carcasses de qualité assez similaires avec des durées d'engraissement variables. A l'intérieur des régimes herbe, le pâturage et l'auge ne conduisait pas aux mêmes résultats. En matière de qualité de la viande, il a été mis en évidence que comme chez tous les caprins, la viande de caprin Créole demeurait relativement maigre même avec des régimes riches en énergie du fait d'une accumulation préférentielle du gras dans la cavité abdominale (4-7 % du poids vif vide). En ce qui concerne les autres caractéristiques des viandes, tels que les profils d'AG et les niveaux de pH, ils sont similaires à ceux de nombreuses races. L'apport de concentrés n'a pas augmenté les AG hypercholestéromiants au sein des AGS dans la viande et a réduit le rapport n-6/n-3 sous la valeur de 4 avec un apport de 240 g de concentré soit un peu moins de 50 % de la ration. Les retombées de ce travail de thèse sont potentiellement importantes. Des bases sont jetées pour la promotion d'itinéraires techniques et de choix génétiques adaptés au contexte guadeloupéen et aussi la création d'une niche économique autour d'une viande de cabri labélisée. L'étude des qualités sensorielles, de l'impact du parasitisme dans les systèmes pâturés et l'évaluation technico-économique de nouveaux systèmes d'alimentation basés sur l'emploi des matières premières locales constituent de nouvelles pistes de recherches mises en évidence par ce travail

Il presente lavoro di tesi è stato finalizzato a valutare l’influenza di alcuni fattori di produzione sui caratteri quali-quantitativi delle carcasse e delle cosce di suini pesanti destinati alla produzione di prosciutto crudo a Denominazione di Origine Protetta (DOP). La raccolta dati (genotipo, numerosità del lotto, peso vivo e della carcassa, età, resa alla macellazione, classificazione della carcassa secondo la scala SEUROP e delle cosce in funzione della destinazione) è stata condotta presso il Gruppo Alimentare Valtiberino, e ha riguardato complessivamente 190 lotti di suini nel periodo compreso da maggio a dicembre 2021. L’esame dei risultati ha messo in evidenza che il tipo genetico di appartenenza dei suini è il principale fattore in grado di modificare la composizione e il valore della carcassa e delle cosce fresche. In particolare, il peso raggiunto alla macellazione e l’adiposità della carcassa sono risultati piuttosto differenziati fra i tipi genetici considerati, e le carcasse appartenenti ai genotipi caratterizzati da una maggiore percentuale di grasso e minore percentuale in tagli magri hanno mostrato un’elevata predisposizione ad essere utilizzate per la produzione di prosciutto di San Daniele DOP, mentre dagli ibridi commerciali dotati di minore adiposità della carcassa e maggiore resa in tagli magri si ricavano cosce impiegate soprattutto per i prosciutti DOP di Parma o Toscano. La notevole variabilità nei pesi vivi alla macellazione dei suini è risultata, inoltre, strettamente associata alle caratteristiche delle carcasse e delle cosce per la produzione dei prosciutti crudi DOP. In particolare, i suini di peso inferiore ai 170 kg hanno fatto registrare un’elevata incidenza di carcasse (>15%) dotate di adiposità non in linea con quanto previsto dai regolamenti delle DOP, mentre i soggetti di peso superiore ai 180 kg hanno evidenziato un’incidenza di cosce declassate per difetti estetici e di qualità considerevole vicina al 25% del totale.

Questo lavoro è stato condotto nell’ambito del tirocinio per la preparazione della tesi presso lo stabilimento di macellazione e lavorazione delle carni avicole Soc. Agr. Guidi di Roncofreddo che si occupa di produzione di diverse tipologie di carni avicole ed è ha avuto lo scopo di individuare le relazioni esistenti tra alcuni fattori pre-macellazione (stagionalità, numerosità del lotto di animali avviati alla macellazione e durata della sosta al macello) ed il tasso di mortalità e la qualità della carcassa. Nell’arco di tempo che va da ottobre 2017 a settembre 2018, sono state raccolte una serie di informazioni relative a: 224 lotti di polli, 231 lotti di faraone, 146 lotti di galli livornesi, 248 lotti di galli ruspanti e 189 lotti di capponi tutti destinati alla macellazione. In generale, è stato osservato che la mortalità tende ad aumentare durante la stagione estiva con punte particolarmente elevate nel pollo, faraona e cappone ed in particolare nei lotti di pollame costituti da un numero limitato di animali. E’ stato osservato inoltre un peggioramento della qualità della carcassa nei lotti costituiti da un numero superiore di animali (probabilmente in relazione ai maggiori danneggiamenti nelle fasi di carico) ed in quelli che hanno sostato per tempi più lunghi prima di essere stati avviati alla macellazione, mentre la stagione ha mostrato risultati fortemente discordanti fra le diverse categorie di pollame: nel pollo e nel gallo ruspante, sono state osservate minori percentuali di declassamento nei lotti macellati nei mesi invernali, al contrario la faraona ed il gallo livornese hanno presentato indici più favorevoli durante l’estate. È stata registrata, infine, la non trascurabile entità del calo peso delle carcasse durante la fase di refrigerazione che è compresa nel range 1,0-1,5% in funzione della categoria di pollame considerata e che potrebbe essere limitata mediante l’adozione di tecnologie più avanzate.

L’étude faisant l’objet de ce mémoire avait pour but d’évaluer les effets des caractéristiques moléculaires du gène de la leptine ovine, une hormone impliquée dans le contrôle des réserves énergétiques de l’organisme et de la satiété, sur les caractères liés à la qualité de la viande et de la carcasse dans une population d’agneaux lourds provenant du Québec. La population à l’étude était composée de 128 individus (½mâles, ½femelles) provenant de deux génotypes : ½Suffolk ¼Romanov ¼Dorset (xSU) et ½Arcott Canadien ¼Romanov ¼Dorset (xCD). Le gène LEP a été séquencé. Le gène a ensuite été séquencé pour chaque individu et ses parents, entre l’exon 2 et l’exon 3, afin d’y chercher des variations dans un segment d’ADN de 2328 paires de bases. Vingt-trois polymorphismes ont été recensés; de ceux-ci, 12 ont été étudiés et ont montré des effets sur la qualité de la viande et de la carcasse. L’expression du gène LEP a été mesurée dans le tissu adipeux sous cutané, à l’aide de la méthode du PCR en temps réel. Des corrélations significatives ont été établies entre l’activité du gène et des variations de paramètres liés à la couleur de la viande chez les agneaux mâles xCD. L’épaisseur du muscle mesurée aux ultrasons chez ce même les animaux de ce même croisement était positivement liée à l’activité du gène. Des corrélations ont aussi été établies entre la concentration de la leptine dans le sang, l’expression du gène LEP et quelques caractères liés au rendement en maigre du muscle longissimus dorsi de même qu’à la couleur de la viande. Les résultats du projet offrent des pistes pouvant mener au développement de marqueurs génétiques qui pourraient aider dans la sélection des ovins reproducteurs, dans le but d’améliorer la qualité de la carcasse et de la viande des agneaux produits au Québec.
The purpose of this study was to evaluate the effects of the molecular characteristics of the ovine leptin gene (LEP) on characteristics related to meat and carcass quality in a lamb population from the Province of Quebec. The studied population consisted of 128 individuals (½ males, ½ females) from 2 crossbreeds : ½Suffolk ¼Romanov x¼ Dorset (xSU) and ½Arcott Canadian ¼Romanov ¼Dorset (xCD). Sequencing of the LEP gene was performed. The gene was then sequenced for each individual and its parents, between exon 2 and exon 3, in order to search for variations within a 2328 base pairs DNA strand. Twenty-three polymorphisms were identified; 12 have been the subject of further studies and have shown interesting effects on meat and carcass quality. Expression of the LEP gene was measured in subcutaneous adipose tissue using the real-time PCR method. Significant correlations were established between gene activity and variations in meat color parameters in male lambs of the xCD crossbreed. The thickness of the muscle measured with ultrasound in this same crossbreed was positively related to the activity of the LEP gene. Correlations were also established between leptin concentration in blood, LEP gene expression, and a few characteristics related to lean yield of the longissimus dorsi muscle as well as the color of the meat. The study of the sheep leptin gene, as part of this project, offers some avenues that could lead to the development of genetic markers that could help in the selection of breeding sheep to improve the meat and carcass quality of lamb produced in Québec.

Le premier objectif de cette thèse était d’évaluer l’effet de différentes vitesses de dégradation de l’énergie et de la protéine au niveau du rumen sur la prise alimentaire, le bilan azoté, la synthèse de protéines microbiennes dans le rumen (PMic) ainsi que la cinétique des nutriments chez le chevreau en croissance. Huit chevreaux Boer ont été distribué dans un dispositif expérimental en carré latin avec le type de grains (orge vs maïs) en parcelle principale (carré). La dégradabilité de l’énergie (grains traités vs non traités) et la dégradabilité de la protéine [tourteau de soya (TS) vs tourteau de soya chauffé (TSC)] dans le rumen formant les parcelles secondaires selon un arrangement factoriel des traitements 2 × 2. L’orge a été roulé et le maïs a été craqué. Les chevreaux recevant le maïs ont eu une excrétion urinaire de purines plus importante lorsqu’ils recevaient le TS plutôt que le TSC alors que le contraire a été observé avec l’orge (P ≤ 0,01). Le grain non traité couplé au TS a permis une plus grande excrétion de purines que lorsque couplé au TSC alors que la dégradabilité de la protéine dans le rumen n’a eu aucun effet lorsque le grain était traité (P ≤ 0,03). Les résultats de cette expérience ont montré que la synthèse de PMic pourrait être maximisée en combinant des grains lentement fermentescible (maïs ou grains entiers) avec une source de protéines rapidement dégradables (TS) dans le rumen. Avec l’orge, un grain plus rapidement fermenté dans le rumen, une synthèse de PMic supérieure a été observée lorsque couplée à une source de protéines lentement dégradables (TSC). Chaque céréale a des caractéristiques particulières. Ainsi, la seconde expérience de cette thèse a été réalisée afin de comparer les effets du maïs et de l’orge sur les performances de croissance, la qualité de la viande et le profil en acides gras (AG) du gras musculaire. Vingt-quatre chevreaux Boer ont été séparés en blocs selon leur poids et assignés à l’un des traitements qui consistaient en différentes proportions orge:maïs dans le concentré : 1) 100:0, 2) 50:50 et 3) 0:100. Quinze de ces chevreaux (n = 5 chevreaux/traitement) ont été abattus. L’ajout d’orge dans le concentré a provoqué une augmentation linéaire de la consommation de concentré (P < 0,01) et une tendance à l’augmentation du gain moyen quotidien (GMQ; P = 0,08). Les qualités de la carcasse et de la viande n’ont pas été influencées par les traitements et une viande de bonne qualité a été obtenue. Les proportions d’AG n-3 et n-6 ont augmenté de façon linéaire (P < 0,01), alors que le ratio AG n-6/n-3 a diminué de façon linéaire (P < 0,01) avec l’inclusion de maïs dans la ration. Finalement, la race est aussi un paramètre connu pour influencer la production et la qualité de la viande. Le but de la dernière expérience de cette thèse était d’évaluer l’effet de la race et du régime alimentaire sur la croissance, les caractéristiques de la carcasse et la qualité de la viande chez le chevreau. Quarante chevreaux de race bouchère (Boer) ou laitière (Alpine et Saanen) ont été séparés en blocs selon leur poids et nourris avec une ration à base de pâturage en rotation intensive ou une ration à base de concentrés. Les chevreaux de race bouchère ont eu un GMQ supérieur aux chevreaux de race laitière (P < 0,01), alors que le régime alimentaire n’a pas eu d’effet sur la croissance des chevreaux des deux races. Pour la majorité des découpes, les chevreaux de race bouchère ont accumulé plus de gras et moins de muscle lorsqu’ils recevaient la ration à base de concentrés plutôt qu’à base de pâturage alors que ces paramètres étaient peu influencés par le régime alimentaire chez les chevreaux de race laitière (régime × race, P ≤ 0,07). Les chevreaux nourris de la ration à base de concentrés avaient un potentiel glycolytique inférieur menant à un pH ultime supérieur de la viande ainsi qu’un ratio n-6/n-3 presque 4 fois plus grand que celui des chevreaux au pâturage (P < 0,01). Ce ratio a été 1,4 fois plus grand pour les chevreaux de race laitière comparé aux chevreaux de race bouchère (P < 0,01). Le pâturage en rotation intensive a permis un gain de poids moyen quotidien semblable à celui obtenu avec la ration à base de concentrés, une accumulation de gras interne moins importante dans la carcasse et une viande de bonne qualité. De plus, les chevreaux de race laitière représentent une alternative intéressante afin de produire de la viande de chèvre.
It has been suggested that microbial protein synthesis in the rumen would be optimized when dietary carbohydrates and proteins have synchronized rates and extent of degradation. The first objective of this thesis was to evaluate the effect of varying ruminal degradation rate of carbohydrates and nitrogen sources on intake, nitrogen balance, microbial protein yield in the rumen, and digestive kinetics of nutrients in the rumen of growing kids. Eight Boer goats were used. The treatments were arranged in a split-plot Latin square design with grain sources (barley or corn) forming the main plots (squares). Grain processing methods (rolled barley and cracked corn vs unprocessed grains) and levels of protein degradability [untreated soybean meal (SBM) vs heat-treated soybean meal (HSBM)] formed the subplots in a 2 × 2 factorial arrangement for a total of eight dietary treatments. Kids fed corn had higher excretion of purine derivatives (PD) when coupled with SBM compared with HSBM and the contrary occurred with barley-fed kids (P ≤ 0.01). Unprocessed grain offered with SBM led to a higher PD excretion than with HSBM whereas protein degradability had no effect when processed grain was fed (P ≤ 0.03). Results of this experiment with high concentrate diets showed that microbial N synthesis in the rumen could be maximized in goat kids by combining slowly fermented grains (corn or unprocessed grains) with a highly degradable protein supplement (SBM). With barley, a more rapidly fermented grain, a greater microbial protein synthesis in the rumen was observed when supplementing a low degradable protein (HSBM). Each cereal used in animal feeding has distinct characteristics. Therefore, the second experiment of this thesis was conducted to compare the impact of corn and barley on growth performance, meat quality, and muscle fatty acid (FA) composition of goat kids. Twenty-four Boer males were blocked by body weight (BW) and allotted randomly within block to one of three experimental diets. Treatments consisted in varying ratios of barley to corn in the concentrate: 1) 100:0, 2) 50:50, and 3) 0:100. Fifteen randomly selected kids (n = 5 kids/treatment) were slaughtered to evaluate carcass traits and meat quality. Inclusion of barley in diet linearly increased concentrate intake (P < 0.01) and tended to increase average daily gain (ADG; P = 0.08). There was no significant difference on carcass traits and meat quality among dietary treatments, and overall good meat quality was obtained. Proportions of n-3 and n-6 FA increased linearly (P < 0.01), whereas the n-6/n-3 FA ratio linearly decreased (P < 0.01) in meat fat as corn inclusion increased in the diets. Finally, breed is a parameter also known to influence meat production and quality. The aim of the last study of this thesis was to evaluate the effects of breed and feeding regimen on growth performance, carcass characteristics, and meat quality of male goat. Forty meat (Boer) or dairy (Alpine and Saanen) goat kids were blocked within breed according to BW. Kids within each block were then randomly allotted to intensive rotational grazing or a concentrate-based diet. Meat kids had a greater ADG than dairy kids (P < 0.01), but feeding treatments did not affect growth rate. For most of the primal cuts, meat kids accumulated more fat and less lean when they were fed concentrate in comparison with pasture, whereas these parameters were less influenced by dietary treatments in dairy kids (feed × breed, P ≤ 0.07). Pasture-fed kids had higher glycolytic potential resulting in lower meat ultimate pH. However, Warner-Bratzler shear force was higher for grazing kids compared with concentrate-fed kids (P < 0.01). Concentrate-fed kids showed an almost 4-fold greater n-6/n-3 FA ratio in meat fat compared with pasturefed kids, whereas this ratio was 1.4-fold greater for dairy kids in comparison with meat kids (P < 0.01). Intensive rotational pasture allowed similar average daily gain in comparison with concentrate-based diet, less internal fat accumulation in the carcass, and good meat quality. Furthermore, dairy breeds represented a valuable alternative for producing goat meat.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 7, 2008) Includes bibliographical references.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: A total of 32 cattle were divided into four groups of eight each (A1-8, A9-16, A17-24, B1-B8) to be slaughtered on different days over a period of 45 days. All the cattle in Groups A were of Bonsmara type and those in Group B were of Charolais type. Three treatments, Tenderstretch (TS), Tendercut (TC) and Hock suspension (HS) were randomly allocated to each of the 48 sides from group A. Only two treatments (TC and HS) were implemented on the carcass sides in Group B alternating between the right and left sides. Two muscles from each side namely Gluteus medius and Longissimus dorsi were evaluated for purge, cooking loss, shear force and sarcomere length after 2, 4, 6, 10 and 14 days of aging. Paired t-Tests were performed for each pair of treatments and each day separately, on all variables accessed (Snedecor, 1980). The differences in purge and cooking loss between treatments were all found to be inconclusive for each day of aging. Although purge had significant differences between the treatments TC and TS for the GM and LD muscle after 14 days of aging (P = 0.0341 and P = 0.0348 respectively) these were found to be open to doubt as the treatment that delivers the most purge differs between muscles and that the two treatments delivered no differences compared to its HS values. Aging had a significant effect on purge as it doubles after 14 days of aging. Cooking loss values only differed significantly on day 2 for the LD muscle between treatments TC and HS. The differences in shear force were all smaller than 0.3205 kg/ 1.27cm and not consistent over all carcasses. A mean positive improvement in tenderness was calculated from high difference in mean values from some carcasses although some carcasses showed a decrease in tenderness when using TS and TC, which suggests that the treatments are of no relevance towards the industry. Although the differences in shear force become smaller as aging commences, it is not constant, a phenomenon most probably due to the variance between animals. Aging again had the most significant effect (P<.0001) on shear force. Correlations between sarcomere lengths and shear force were low for all the treatments on the GM muscle (HS = -0.453; TC = -0.401 and TS = -0.2) but in the LD muscle the TS method showed a higher correlation (TS = -0.665) than the other treatments (HS = 0.059 and TC = 0.059).
AFRIKAANSE OPSOMMING: `n Totaal van 32 beeste was opgedeel in vier groepe van agt elk (A1-8, A9-16, A17-24, B1-B8) wat geslag is op verskillende dae oor n periode van 45 dae. Beeste van die A groep was almal Bonsmara tipe en die van die B groep charolais tipe. Drie behandelings naamlik Tenderstretch (TS), Tendercut (TC) en Hak suspensie (HS) was ewekansig tot die 48 sye van die karkasse van groep A toegedeel. Groep B se 16 sye is net met TC en HS ewekansig tot die linker en regter sy toegedeel. Twee spiere naamlik Gluteus medius en Longissimus dorsi was geevalueer vir drup verlies, kook verlies, sarkomeer lengte en taaihied na 2, 4, 6, 10 en 14 dae se veroudering. Gepaarde t – toetse is gedoen vir elke paar behandelings vir elke dag van veroudering op al die veranderlikes genoem. Die verskil in drup verlies en kook verlies tussen behandelings was as nie betekeinisvol bestempel. Behalwe vir die feit dat drup verlies betekenisvolle verskille getoon het tussen die behandelings TC en TS vir die GM (P = 0.0341) en die LD (P = 0.0348) spiere na 14 dae se veroudering was dit bevind as nie betekenisvol juis oor dat die twee behandelings teenoor hul HS waardes geen verskille getoon het nie. Veroudering van die vleis het wel die grootste betekenisvolle verskil in drupverlies gemaak waar dit amper verdubbel soos die vleis verouder vir 14 dae. Kookverlies het net op dag twee n betekenisvolle verskil getoon in die LD spier vir die HS – TC kombinasie. Die verskil in taaiheid was almal kleiner as 0.3205 kg/ 1.27cm en nie kostant vir alle karkasse nie. n’ Positiewe gemiddelde verbetering in sagtheid is verkry deur die kalkulasie van hoë positiewe waardes en lae negatiewe waardes vir sommmige karkasse wat n laer sagtheid getoon het wanneer TS en TC gebruik is. Hierdie onkonsekwente verbeterings in sagtheid maak dat hierdie behandelings van min praktiese nut vir die bedryf is. Alhoewel hierdie verskille tussen behandelings kleiner raak tydens veroudering, is dit nie konstant nie, wat as gevolg van die variasies tussen diere kan wees. Veroudering het weereens die mees betekenisvolle effek op die vleis getoon (P< 0.001). Die korrelasie tussen sarkomeer lengte en WBSF taaiheid was laag vir alle behandelings in die GM spier (HS = -0.453; TC = -0.401 en TS = -0.2) behalwe vir die LD spier waar die TS behandeling n hoer korrelasie van TS = -0.665 as die ander twee behandelings (HS = 0.059 en TC = 0.059) opgelewer het.

Master of Science
Department of Animal Science and Industry
Jim L. Nelssen
Three experiments used 777 pigs to study the effects of fiber source; wheat middlings (midds), dried distillers grains with solubles (DDGS), and choice white grease (CWG), and reduction strategies for growing and finishing pigs. Also a fourth study utilizing 1,360 pigs was conducted to determine the effect of immunocastration (IC) and DDGS withdrawal on growth performance, carcass characteristics, fatty acid analysis, and iodine value (IV) of pork fat depots in growing and finishing pigs. Experiment 1 determined that the ingredient source of fiber (wheat middlings or DDGS) was more important than NDF level alone, for characterization of growth, carcass, and yield responses. Experiment 2 showed that a short (23 d) fiber reduction strategy was successful at fully recovering yield loss; however, a longer reduction (47 d) was necessary for further improvements in carcass fat quality (IV). Experiment 3 further proved that yield loss can be recovered with a short fiber reduction strategy (19 d), and that adding energy from CWG during the fiber reduction period can improve feed efficiency, but was unsuccessful at further improving carcass yield or carcass fat quality. Experiment 4 showed that carcass yield was lower for IC pigs than barrows regardless of dietary DDGS or withdrawal strategy. Also pigs fed 30% DDGS throughout had decreased carcass yield; however, withdrawing DDGS from the diet on d 74 was effective at recovering the yield loss. While DDGS withdrawal strategy was successful at lowering IV, but was unsuccessful at fully lowering IV to values of pigs fed the control diet throughout. Iodine values were somewhat variable within fat depot, showing the jowl and clear plate fat were less accurate in showing changes from the diet, most likely due to the fact they are deposited earlier and are slower to turnover. Iodine value tended to be greater for IC pigs than barrows on d 107, but by d 125 there were no differences in IV between IC and barrows. This dramatic improvement from d 107 to 125 could be caused by the dilution of unsaturated fatty acids, specifically C18:2 and C18:3, due to the rapid deposition of fat in IC pigs.

Rapid growth within the Australian alpaca industry has increased interest in alpaca meat as a viable alternative to traditional fibre production, driving research into alpaca meat eating quality. However, product quality and inconsistency are limiting market growth. Meat quality is impacted by many factors throughout the supply chain, including pre-slaughter handling, processing conditions, packaging and cooking. In order to improve quality, the impact of these factors on alpaca needs to be considered. In order to address these knowledge gaps and maximize quality and efficiency throughout the alpaca meat supply chain, the following research was conducted. Three separate studies were conducted across three consecutive years in order to investigate the thesis aims. The first study (Chp 2) sought to investigate the effects of season and post-transport resting on alpaca meat quality. A total of 160 castrated male huacaya alpacas (23 ± 1 month of age) were transported to slaughter over a 12-month period. Animals were transported in two groups of 20 per season to generate 8 replicate trials across the year. Immediately following transport, animals were allocated to one of two treatment groups at the abattoir (overnight pre-slaughter lairage or a seven-day pre-slaughter rest period with ad lib access to feed and water). Animals were processed under commercial conditions and chilled for 24 h prior to the removal of the m. Longissimus thoracis (LT) from the right-hand side of each carcase. Results indicated that alpaca meat quality varied across the year, with increased moisture loss through summer and spring and a trend toward improved summer tenderness. Resting alpacas for 7 days pre-slaughter had a negative effect on meat quality, with reduced muscle glycogen content and tenderness, and increased moisture loss. The second study (Chp 3 and 4) investigated the effects of combining tenderstretching (TS) with medium voltage electrical stimulation (ES) during processing on tenderness, oxidation and eating quality traits of alpaca. Thirty-six castrated male huacaya alpacas (23 ± 1 month of age) were processed over 2 days, two months apart. Carcases were split and treatments applied to sides at random, in a 2×2 factorial arrangement. Treatments included; (1) Achilles Hung + No ES; (2) Achilles Hung + ES; (3) TS + No ES; and (4) TS + ES. After 24 hours chilling, carcase sides were broken down and the Longissimus thoracic et lumborum (LTL), Adductor femoris (AF), Semimembranosus (SM), Semitendinosus (ST) and Psoas major (TL) muscles were extracted for meat quality and consumer sensory evaluation. Results indicated that combined processing treatments improved alpaca meat SF and eating quality across the carcase, while having no detrimental effects on colour stability and oxidation. However, alpaca LTL SF values remained high comparative to that of hind quarter muscles. The third study (Chp 5) aimed to build on the findings study one and two. The effect on alpaca meat quality from applying medium voltage ES in combination with TS to whole carcases was investigated, along with the effect of enzyme (actinidin) infusion on alpaca LTL quality. Thirty-six entire male huacaya alpacas (23 ± 1 month of age) were processed over two days, two weeks apart. Carcases were randomly allocated to one of two processing treatments; (1) Achilles hung + No ES, and (2) TS + ES, in order to investigate the effect of combined processing methods on whole alpaca carcases. After 24 h, carcases were broken down with both the left-and-right-hand-side LTL of each carcase allocated to one of three infusion treatments, including; (1) no infusion; (2) infusion with water, and; (3) infusion with enzyme. In addition, the SM from the right hind leg of each carcase was collected for meat quality evaluation. Results supported the use of combined TS with ES in commercial alpaca processing and indicated no advantages in infusing alpaca LTL with actinidin. The results indicate that maximising on-farm feed quality and availability leading to slaughter and avoiding lengthy lairage periods after 4 h transportation will maximise alpaca carcase tenderness. Residual variation in quality across multiple muscles arising from intrinsic factors such as nutrition and pre-slaughter stress can be minimised through the application of ES and TS in combination. Due to the limitations in achieving optimal alpaca LTL tenderness, it is suggested that a fresh market for the product be avoided until consumers become more familiar with the novel meat, focussing instead on value added, ready to eat product development and sales through restaurant trade. Future areas of research for alpaca must focus on genetic influences and specific biochemical processes occurring during the toughening and tenderisation phases of processing in order to further the understanding of alpaca meat tenderness.

Reducing variation in tenderness is a goal for the meat industry. The objective of this study was to determine if different growth patterns, not caused by nutrient restriction, impacted carcass characteristics and tenderness. Simmental × Angus steers (n = 18) reared under similar conditions, fed in the same pen at the feedlot, were allocated into fast (n = 9) and slow (n = 9) growing groups based upon four sets of weight data. After slaughter, carcass data were obtained. The striploin was removed, cut into steaks, and aged for 1, 3, 7, 14, and 21 days. For each aging period, one steak per steer underwent evaluation of shear force and MFI. Myofibrils were isolated from aged muscle samples and protein degradation was visualized with the use of SDS-PAGE. Carcass weight (P< 0.0001) and LD area (P = 0.0093) were significantly affected by growth rate. Shear force (P = 0.0003) and MFI (P< 0.0001) were significantly affected by length of aging, but not by growth rate (P≥ 0.3184); nor was there a significant interaction between growth rate and length of aging (P≥ 0.6555). Even though the shear force × growth rate finding was not statistically significant, shear force of steaks from fast-growing animals had a greater reduction in shear force values indicating a difference in early tenderization. A currently unidentified protein with a molecular weight between 130 and 100kDa was seen earlier postmortem in more tender muscle. This degradation was more apparent in muscle from fast growing steers. A 30kDa component also appeared earlier, and at a greater band intensity, in more tender muscle. Degradation of the 30kDa component was also more evident in fast growing steers. These results suggest that there is a difference in protein degradation in muscle from animals with differing growth paths. The results of this study suggest that more research is warranted to identify differences in protein degradation due to growth rate and to elucidate the effect of growth rate on variation in tenderness.

Forage halophytes such as saltbush (Atriplex spp) are being widely used to revegetate Australian saline land and can also provide a medium quality fodder source. There is widespread anecdotal evidence that sheep grazing on saltbush are leaner, tastier and juicer. This thesis investigated the potential to produce a high quality carcass with improved eating quality from grazing sheep on saltbush on saline land. The first experimental chapter in this thesis details an animal house experiment investigating the carcass, eating and wool quality and physiological responses of sheep ingesting a 60:40 dried saltbush (Atriplex nummularia):barley grain (S+B), ration verses a 33:25:42 lupin grain:barley grain:oaten hay ration (Control, C) for 10 weeks prior to commercial slaughter (Chapter 4). Subsequently, two field experiments were conducted to examine the effects of grazing saltbush on saline land compared to dry senesced pasture on carcass and eating quality of lambs (Goomalling 2003) and hoggets (Wickepin 2004) (both chapter 6) for 14 weeks. Both chapters demonstrated that the ingestion of saltbush resulted in significantly less fat and in the 2 field experiments the ingestion of saltbush resulted in more lean on the carcass compared to sheep grazing a stubble/pasture (control) ration. These are positive findings for processors as costs of fat denudation are high so the lower the fat content and for farmers because less fat is deposited on the carcass per unit of liveweight gain. The decreased deposition of fat was attributed to the higher protein:energy ratio available for production, secondary compounds in saltbush and lower circulating insulin and higher growth hormone of the S+B fed sheep compared to the control fed sheep. Further work is needed to determine if these beneficial improvements in carcass composition can be achieved without compromising animal production. The long term grazing of saltbush did not result in commercially desirable hot carcass weights unless the sheep were supplemented with a high energy source such as barley. The low growth rates are attributed to a decreased availability of energy substrates, low feed intake and increased energy output of sheep fed high salt diets. The low energy intake of the S+B fed sheep also resulted in an a significantly lower percentage of unsaturated fat and unchanged levels of saturated fat in the fat depots compared to the C treatment. Consumer taste tests conducted on meat from experiments in both chapter 4 and 6 indicated no difference between the treatments for any of the eating quality traits assessed. This can be considered a positive result as sheep can be finished on saltbush without any detriment to eating quality. High vitamin E levels in the meat may have also prevented the development of rancid flavours and aroma. It can be speculated that saltbush does not impart beneficial flavour and aroma volatiles as previously thought; instead the high vitamin E levels inhibit off-flavour and aroma development compared to meat from sheep grazed on dry pasture. The long term ingestion of saltbush also resulted in significantly lower urine specific gravity (USG), muscle dry matter and higher urine weights suggesting that the saltbush fed sheep had a better hydration status compared to control fed sheep. However, this finding did not correspond with higher hot carcass weight or dressing percentages. The increases in muscle fluid content of the saltbush fed sheep were attributed to changes in body composition. The saltbush fed sheep had a higher lean and lower fat content which corresponded with a greater body fluid content as found in the animal house study. Under conditions where the body composition of sheep remains the same, the use of short term strategic feeding of components of saltbush was investigated (mimicked in the form of salt and betaine) to reduce dehydration and subsequent reductions in carcass weight and dressing percentages (Chapter 7). Salt and or betaine were fed for 1 week either prior to a 48 h period of water deprivation or prior to 48 h commercial slaughter process where water was available in lairage from 24-48 h. Under both scenarios the diets did not result in improved dressing percentages, hot carcass weights, muscle dry matter or muscle weights. The ingestion of high salt diet prior to slaughter, did increase fluid retention in the extracellular spaces prior to slaughter however by 48 h both groups were at a similar physiological and therefore similar hydration status. Therefore similar levels of fluid were present in the muscles and no difference in carcass weight or dressing percentage could be expected. An important observation from the second experiment was that the high salt group drunk more water than the low salt fed sheep but the low salt group consumed fluid in lairage also. The low salt fed sheep may have been encouraged to drink water after observing the frequent drinking patterns of the high salt group. This thesis has also shown that saltbush contains high levels of vitamin E (á-tocopherol) (193 mg/kg dry matter). As a result the concentration of á-tocopherol in plasma, liver and muscle of the saltbush fed sheep was elevated compared to those grazing dry pasture. The high muscle concentrations of vitamin E in the saltbush-grazed sheep resulted in improved meat colour stability. The high vitamin E levels did not influence the drip and cooking loss of the meat despite a decrease in the muscle dry matter of the meat. The browning of meat and increased drip loss results in large losses to the meat industry due to value deterioration at the supermarket. There is also great potential for the high vitamin E content in saltbush to be used for the prevention of nutritional myopathy instead of using expensive and labour intensive synthetic supplements. In conclusion, this thesis has provided an insight into the carcass and eating quality of sheep grazed on saltbush based saline pasture systems. The most significant findings were that

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Conselho Nacional de Desenvolvimento Científico e Tecnológico
Este trabalho foi conduzido com o objetivo de avaliar os efeitos da adição de cromo, ácido linoleico conjugado, e ractopamina no desempenho, características de carcaça e qualidade de carne de suínos abatidos aos 115 kg. Foram utilizados 96 suínos machos castrados com peso inicial de 70,21 ± 1,98 kg. Os animais foram distribuídos ao acaso em seis tratamentos. Foram utilizadas oito repetições por tratamento e dois animais por unidade experimental (48 baias, 2 suínos por baia). Os tratamentos consistiram de uma dieta controle (CON) formulada para atender as exigências nutricionais de suínos machos castrados de alto potencial genético. As demais dietas foram formuladas utilizando a dieta CON como base, à qual foram adicionados os aditivos a serem testados, da seguinte maneira: 400 ppb de cromo levedura (CrL); 0,5% de CLA (CLA); 400 ppb CrL e 0,5% CLA (CrL+CLA); 20 ppm de ractopamina (RAC); 400 ppb cromo levedura e 20 ppm de ractopamina (CrL+RAC). Os níveis de lisina nas dietas contendo ractopamina foram aumentados em 20% em relação à dieta CON. Os suínos alimentados com RAC e CrL+RAC receberam a dieta CON durante os primeiros 17 dias de experimento, e passaram a consumir as respectivas dietas nos últimos 28 dias de experimento. As médias entre os tratamentos contendo aditivos foram comparadas usando o teste Tukey. A média de cada tratamento contendo aditivos foi comparada à média da dieta CON utilizando o teste Dunnett. O peso médio inicial foi usado como covariável. Os suínos alimentados com RAC e CrL+RAC apresentaram maior (P < 0,01) peso final e ganho de peso médio diário do que os suínos dos demais tratamentos. A eficiência alimentar foi maior (P < 0,01) nos suínos recebendo CrL+RAC em comparação com os suínos recebendo dieta contendo aditivos, com exceção dos animais alimentados com RAC, que tiveram eficiência alimentar similar aos alimentados com CrL+RAC. Suínos alimentados com RAC e CrL+RAC apresentaram eficiência alimentar semelhantes, ambas superiores (P < 0,01) à eficiência alimentar dos animais alimentados com dieta CON. O consumo de ração foi semelhante (P = 0,89) para todas as dietas. Suínos alimentados com CrL+RAC apresentaram maior área de olho de lombo (AOL) (P < 0,01) e rendimento de carcaça (P < 0,05) do que os animais alimentados com as dietas CON, CrL, CLA e CrL+CLA. Os resultados de AOL e rendimento de carcaça de suínos alimentados com RAC foram similares aos resultados obtidos nos animais alimentados com as demais dietas. Os animais alimentados com CLA, RAC e CrL+RAC apresentaram menor (P = 0,22) espessura de toucinho quando comparados aos animais recebendo dieta CON. Os aditivos não influenciaram o pH (P > 0,05), a temperatura (P > 0,05), as perdas de água (P = 0,87) e a força de cisalhamento (P = 0,70) da carne. Menores valores de L* foram encontrados na carne de suínos alimentados com CrL+CLA em comparação aos suinos alimentados com CON (P < 0,05) e RAC (P < 0,01). Suínos alimentados com RAC apresentaram menores (P < 0,05) valores de a* em comparação aos suinos alimentados com CON. Os valores de b* foram semelhantes (P = 0,20) para todas as dietas. Não houve diferença significativa (P = 0,89) na concentração de gordura intramuscular. Não foram observadas diferenças nas concentrações séricas de glicose (P = 0,32), colesterol (P = 0,67) e triglicerídeos (P = 0,46). A concentração sérica de ureia foi menor (P = 0,03) nos suinos alimentados com CrL+RAC em comparação aos suinos alimentados com CON e RAC. A suplementação combinada de cromo e ractopamina aumenta a AOL e o rendimento de carcaça de suínos em terminação, sugerindo a existência de um sinergismo que pode estar relacionado a capacidade de cromo de aumentar a utilização de nutrientes em suinos suplementados com ractopamina. Os aditivos suplementados não apresentam efeitos importantes sobre a qualidade de carne.
This study aimed to evaluate the effects of dietary chromium, CLA, and ractopamine on performance and pork quality of finishing pigs slaughtered at 115 kg BW. Ninety-six crossbred barrows (initial BW= 70.21 ± 1.98 kg) were randomly assigned to 1 of 6 dietary treatments. A diet formulated according to the nutritional requirements of 70- to 100-kg barrows of high lean genotype gaining l.l3 kg/day was used as the control (CON). The other five diets were based on the CON and supplemented as follows: 400 ppb Cr yeast (CrY); 0.5% CLA (CLA); 400 ppb CrY and 0.5% CLA (CrY+CLA); 20 ppm RAC (RAC); 400 ppb CrY and 20 ppm RAC (CrY+RAC). Lysine levels on diets containing RAC were raised by 20% compared to CON. Pigs fed RAC and CrY+RAC were fed CON for the first 17 d, and then the respective diets for the last 28 d on trial. There were 8 replicates per treatment (48 pens; 2 pigs per pen). Means were compared using Tukey test, excluding the CON. Dunnett test was used to compare the means of each diet containing additives to the CON. Initial BW was used as covariate. Pigs fed RAC and CrY+RAC had the highest (P < 001) final BW and ADG. Pigs fed CrY+RAC had higher (P < 001) G:F than pigs fed diets containing additives, except for the RAC. Pigs fed CrY+RAC and RAC had similar G:F, both higher (P < 001) than pigs fed CON. Feed intake was similar (P = 0.89) for all diets. Pigs fed CrY+RAC had higher LM area (P 005) and carcass yield (P < 001) than pigs fed CON, CrY, CLA, and CrY+CLA. Loin muscle area and carcass yield of pigs fed RAC were not statistically different from pigs fed the others diets tested. Back fat depth was lower (P = 022) in pigs fed CLA, RAC and CrY+RAC compared to pigs fed CON. The additives did not affect pork pH (P > 005), temperature (P > 005), water losses (P = 0.87), and shear force (P = 0.70). Lower L* values were found on pork from pigs fed CrY+CLA compared to pigs fed CON (P < 005), and RAC (P < 0.01). Pigs fed the RAC had lower (P 005) a* values compared to pigs fed CON. Pork b* values were similar (P = 0.20) for all diets. There were no significant differences (P = 089) on intramuscular fat content. Serum urea nitrogen (SUN) concentration was lower (P = 003) in pigs fed CrY+RAC than in pigs fed CON and RAC. In summary, when combined, CrY and RAC increase LM area and carcass yield and reduce SUN, suggesting a synergism that might be related to the ability of Chromium to improve nutrient utilization in RAC-fed pigs. Additionally, CrY, CLA and RAC have no major effects on pork quality.

Skin damage and meat quality are very important issues for the whole pig industry as well as animal welfare. To investigate the real impact of pre-slaughter period and its entity on carcass apperance and meat quality, a Risk Assessment approach was applied on 1680 Italian heavy pigs which were examinated and frequency of pigs’behaviour was recorded and related to carcass, ham, loin and shoulder/head damage. The operators’handling was recorded too. The main potential cause of damage both unloading and to the stunning resulted the use of driving devices by operators for the highest frequency and calculated risk of lesions. The effect of pre-slaughter stress was also evaluated on some quality traits of pork. Twenty-eight pigs of different breed (Italian large White, Italian Duroc and Pietrain) were subjected to rough and gently handling before stunning and the level of lactate, pro-, macro- and total glycogen were evaluated in longissimus dorsi and semimembranosus musles. Pigs rough handled before death tended to presents muscles with lower level of pro-, macro- and total glycogen and higher level of lactate, with little differences among breeds. Also transport is known to be another very stressful event for pigs which influence skin damage score and meat quality. Data of 3.650 heavy pig batches were collected to identify the relationship between the transport and ham estetical and technological defects that make them rejected from PDO Parma Consortium. The results shown that short (<37 km) or long (>170 km) travel distances may have adeverse effects on the incidence of defects on fresh hams together the season of transport, where Autumn and Spingtime are the seasons with highest incidence of ham defects. It’s clear that pre-slaughter events as transport and handling affect animal welfare and ham defects, total carcass damage and meat quality parameters.

Skin damage and meat quality are very important issues for the whole pig industry as well as animal welfare. To investigate the real impact of pre-slaughter period and its entity on carcass apperance and meat quality, a Risk Assessment approach was applied on 1680 Italian heavy pigs which were examinated and frequency of pigs’behaviour was recorded and related to carcass, ham, loin and shoulder/head damage. The operators’handling was recorded too. The main potential cause of damage both unloading and to the stunning resulted the use of driving devices by operators for the highest frequency and calculated risk of lesions. The effect of pre-slaughter stress was also evaluated on some quality traits of pork. Twenty-eight pigs of different breed (Italian large White, Italian Duroc and Pietrain) were subjected to rough and gently handling before stunning and the level of lactate, pro-, macro- and total glycogen were evaluated in longissimus dorsi and semimembranosus musles. Pigs rough handled before death tended to presents muscles with lower level of pro-, macro- and total glycogen and higher level of lactate, with little differences among breeds. Also transport is known to be another very stressful event for pigs which influence skin damage score and meat quality. Data of 3.650 heavy pig batches were collected to identify the relationship between the transport and ham estetical and technological defects that make them rejected from PDO Parma Consortium. The results shown that short (<37 km) or long (>170 km) travel distances may have adeverse effects on the incidence of defects on fresh hams together the season of transport, where Autumn and Spingtime are the seasons with highest incidence of ham defects. It’s clear that pre-slaughter events as transport and handling affect animal welfare and ham defects, total carcass damage and meat quality parameters.

The consumer is becoming more conscious about the quality of products and he is willing to pay more for superior products. To respond to the new and diversified consumer demand it is necessary to develop animal production with concerns of safe and quality products. Meat quality is a complex concept including carcass composition and conformation, lack of microbiological hazards, animal welfare and environmental impact. Traits concerning beef quality have low/medium heritabilities, and measures are difficult and expensive to be carried out. The development of DNA technologies applied to cattle represents a promising tool suitable to solving these problems. Markers found in various candidate genes linked to quality traits have been identified and included into a commercially genetic test for carcass/beef quality traits. However, before including these candidate genes in genetic tests and using them in breeding programs it is important to perform validation studies in different breeds to establish whether the observed marker effects are found in the breed or population of interest. Aims of this thesis were to analyze a group of candidate genes polymorphisms in order to provide further information about their allelic frequencies in Piemontese population and their association with the main carcass/beef quality traits. A prescreening was carried out to investigate the variability of a set of polymorphisms located in 15 candidate genes for meat quality traits. Meat samples of Longissimus thoracis muscle collected on 1,208 Piemontese young bulls, progeny of 109 AI sire, were available. Phenotypic data for carcass and meat quality traits used included carcass weight (CW), shear force (SF), cooking loss (CL) and pH (pH24h). For each trait, 48 samples were chosen from each tail of the trait distribution. One or more single nucleotide polymorphisms (SNPs) were determined in the following candidate genes: calpastatin (CAST), calpain 1 (CAPN1), B and D cathepsin (CTSB, CTSD), growth hormone (GH), growth hormone receptor (GHR), pro-opiomelanocortin (POMC), pituitary-specific positive transcription factor 1 (POU1F1), melanocortin-4 receptor (MC4R), corticotrophin-realising hormone (CRH), insulin-like growth factor binding protein-3 (IGFBP3), diacylglycerol acyltransferase 1 (DGAT1), thyroglobulin (TG), carboxypeptidase E (CPE), and protein kinase adenosine monophosphate-activated γβ-subunit (PRKAG3). A total of 20 SNPs were genotyped using allele refractory mutation system polymerase chain reaction (ARMS-PCR) or restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR). Allelic frequencies, test for Hardy-Weinberg (HW) equilibrium, as well as genic differentiation for sampled populations (i.e., 2 sub-populations per trait corresponding to the tails of its phenotypic distribution) were obtained using Genepop software version 4.0. A total of 6 SNPs showed a minor allele frequency less than 10%. Samples from the tails of each trait distributions were treated as different populations to investigate any possible difference in allelic frequencies. Only MC4R locus showed a significant difference in the allelic frequency across tails for CW. Based on these results, only variable loci were further investigated (Chapter 3). It was demonstrated that calpain system (μ-calpain, m-calpain, and calpastatin) and a lysosomal enzyme (cathepsin) influence some meat quality traits. In this study, 5 SNPs previously tested: CAPN530 (AF_288054.2:g.4558G>A), CAPN4751 (AF_288054.2:g.6545C>T), CAST2959 (AF_159246.1:g.2959A>G), CAST2870(AF_159246.1:g.2870A>G), CAST282 (AY_008267:g.282G>C) and CTSD (AB_055312:g.77G>A), were investigated in 990 Piemontese young bulls. A univariate Bayesian mixed-inheritance animal model was used to evaluate the effects of genotypes on variation of pH24, lightness (L*), redness (a*), yellowness (b*), cooking loss (CL), drip loss (DL), and shear force (SF). An association was observed only for CAST282 G allele and CAPN530 A allele on DL, CAPN530 A allele was also associated with b* and CAST2959 A allele with a*. It is reasonable to hypothesize that the effect obtained in this study might has been due to a variation of degradation of myofibril proteins and consequently activation/deactivation of drip channel that origin drip losses (Chapter 4). The last 10 variable polymorphisms tested in the prescreening phase were: GH1547 (M57764:g.1547TC>G), GHR257 (AF_140284:g.257A>G), POMC254 (J00021:g.254C>T), POU1F1 208 (EF090615:g.208A>G), MC4R1069 (AF_265221:g.1069C>G), CRH240 (AF_340152:g.240G>C), DGAT10343 (AJ_318490:g.10343GC>AA), TG1696 (M35823:g.1696C>T), CPE601 (AY_970663:g.601C>T), and PRKAG3 1609 (AY_692035:g.1609G>A). All of these SNPs were analyzed to calculate allelic frequency and to test their association with CW, pH24h, L*, a*, b*, CL, DL, and SF. All SNPs were informative in Piemontese population except for CPE601. Bayesian association analysis showed that 8 out of the 10 investigated SNPs had and additive deviation with at least one of the carcass and beef quality traits investigated. Some of these associations were new, whilst others confirmed previous investigations (Chapter 5).
Il consumatore sta diventando sempre più consapevole della qualità dei prodotti alimentari ed è disposto a pagare di più prodotti di qualità superiore. Per far fronte alle nuove e diversificate richieste dei consumatori, è necessario migliorare la produzione animale prestando particolare attenzione alla sicurezza e alla qualità. La qualità della carne è un concetto complesso che include composizione e conformazione della carcassa, assenza di rischi microbiologici, benessere animale e impatto ambientale. I caratteri che influenzano la qualità delle carni bovine hanno ereditabilità medio/bassa e inoltre misurarli è spesso difficile e costoso. Lo sviluppo delle tecnologie basate sul DNA, applicate agli animali da reddito, rappresenta un promettente strumento adatto a risolvere tali problemi. Molti marcatori presenti su geni candidati per la qualità della carne sono stati identificati e inclusi in test disponibili in commercio. Tuttavia prima di utilizzare questi test in programmi di miglioramento genetico è importante valutare se e quali effetti questi geni hanno nella popolazione in cui si vogliono utilizzare. Gli obiettivi di questa tesi sono stati: analizzare un gruppo di polimorfismi di geni candidati, al fine di fornire informazioni sulle loro frequenze alleliche nella popolazione Piemontese e valutarne l’associazione con i caratteri per la qualità della carcassa e della carne. Una pre-analisi è stata eseguita per individuare la variabilità di venti polimorfismi a singolo nucleotide (SNP) situati su quindici geni candidati per la qualità della carne. I campioni di Longissimus thoracis sono stati prelevati da 1.208 vitelloni Piemontesi, generati da 109 tori del centro d’inseminazione artificiale. Su tali campioni erano disponibili i dati fenotipici per la conformazione della carcassa e per la qualità della carne: peso della carcassa (CW), forza di taglio (SF) perdite di cottura (CL), e pH (pH24). Per ogni carattere, quarantotto campioni sono stati scelti da ciascuna delle due code della distribuzione normale del carattere stesso. Uno o più polimorfismi a singolo nucleotide (SNP) sono stati determinati nei seguenti geni candidati: calpastatina (CAST), calpaina 1 (CAPN1), B e D catepsina (CTSB, CTSD), ormone della crescita (GH), recettore dell’ormone della crescita (GHR), pro-opiomelanocortina (POMC), POU classe 1 homeobox 1 (POU1F1), recettore della melanocortina-4 (MC4R), ormone corticotropina rilasciante (CRH), proteina legante il fattore di crescita insulino-simile 3 (IGFBP3), diacilglicerolo aciltransferasi 1 (DGAT1), tireoglobulina (TG), carbossipeptidasi E (CPE) e subunità -γβdella proteina chinasi AMP-attivata (PRKAG3). Venti SNPs sono stati sottoposti a genotipizzazione mediante tecniche basate sulla reazione a catena sella polimerasi (PCR). Le frequenze alleliche, il test di equilibrio di Hardy-Weinberg (HW), così come la differenziazione genica per le popolazioni campionate (ovvero, due sub-popolazioni una per ciascuna coda della distribuzione del carattere) sono stati ottenuti utilizzando il software Genepop la versione 4.0. Un totale di sei SNPs ha presentato alleli minori con frequenza inferiore al 10%. I campioni presi delle code delle distribuzioni di ogni carattere sono stati trattati come popolazioni diverse al fine di rilevare eventuali differenze tra le frequenze alleliche. Solo il locus MC4R ha mostrato una differenza statisticamente significativa nella distribuzione allelica tra le due popolazione per il CW. I loci variabili ottenuti da questa prima analisi saranno analizzati su tutto il campione (capitolo 3). E’ stato dimostrato che sia il sistema calpaina/calpastatina (μ-calpaina, m-calpaina e calpastatina) sia un enzima lisosomiale (catepsina) influenzano alcuni caratteri legati alla qualità della carne. In questo studio cinque SNP, testati in precedenza: CAPN530 (AF_288054.2: g.4558G> A), CAPN4751 (AF_288054.2: g.6545C T>), CAST2959 (AF_159246.1: g.2959A> G), CAST2870 (AF_159246.1: g.2870A> G), CAST282 (AY_008267: g.282G> C) e CTSD (AB_055312: g.77G> A) sono stati genotipizzati su 990 vitelloni Piemontesi. Un animal model implementato con metodi Bayesiani è stato utilizzato per valutare gli effetti dei genotipi sulle variazione di pH24, di luminosità (L *), del rosso (a *), del giallo (b *), delle perdite di cottura (CL), delle perdite di gocciolamento (DL) e della forza di taglio (SF). L'associazione con la DL è stata osservata solo per CAST282 allele G e CAPN530 allele A. L’allele A di CAPN530 ha presentato associazione anche con a * e b * e l’allele A di CAST2959 con a*. Si potrebbe ipotizzare che l'effetto ottenuto, in questo studio, sul DL sia dovuto ad una variazione nella degradazione delle proteine miofibrillari che determina l'attivazione/disattivazione dei canali causando così la perdita d’acqua (capitolo 4). Gli ultimi dieci polimorfismi, risultati variabili nelle pre-analisi, sono: GH1547 (M57764: g.1547TC> G), GHR257 (AF_140284: g.257A> G), POMC254 (J00021: g.254C T>), POU1F1 208 (EF090615: g 0,208 A> G), MC4R1069 (AF_265221: g.1069C> G), CRH240 (AF_340152: g.240G> C), DGAT10343 (AJ_318490: g.10343GC> AA), TG1696 (M35823: g.1696C T>), CPE601 (AY_970663: g.601C T>), e PRKAG3 1609 (AY_692035: g.1609G> A). Tutti questi SNP sono stati genotipizzati per calcolarne le frequenze alleliche e per testare la loro associazione con CW, PH24h, L *, a *, b *, CL, DL, e SF. Tutti gli SNPs sono risultati informativi nella popolazione Piemontese, tranne CPE601. L’Analisi statistica ha dimostrato che otto dei dieci SNPs indagati avevano effetto additivo con almeno un carattere relativo alla qualità della carcassa e delle carni bovine. Alcune di queste associazioni sono presentate per la prima volta, mentre altre hanno confermato studi già effettuati (capitolo 5).

Forage halophytes such as saltbush (Atriplex spp) are being widely used to revegetate Australian saline land and can also provide a medium quality fodder source. There is widespread anecdotal evidence that sheep grazing on saltbush are leaner, tastier and juicer. This thesis investigated the potential to produce a high quality carcass with improved eating quality from grazing sheep on saltbush on saline land. The first experimental chapter in this thesis details an animal house experiment investigating the carcass, eating and wool quality and physiological responses of sheep ingesting a 60:40 dried saltbush (Atriplex nummularia):barley grain (S+B), ration verses a 33:25:42 lupin grain:barley grain:oaten hay ration (Control, C) for 10 weeks prior to commercial slaughter (Chapter 4). Subsequently, two field experiments were conducted to examine the effects of grazing saltbush on saline land compared to dry senesced pasture on carcass and eating quality of lambs (Goomalling 2003) and hoggets (Wickepin 2004) (both chapter 6) for 14 weeks. Both chapters demonstrated that the ingestion of saltbush resulted in significantly less fat and in the 2 field experiments the ingestion of saltbush resulted in more lean on the carcass compared to sheep grazing a stubble/pasture (control) ration. These are positive findings for processors as costs of fat denudation are high so the lower the fat content and for farmers because less fat is deposited on the carcass per unit of liveweight gain. The decreased deposition of fat was attributed to the higher protein:energy ratio available for production, secondary compounds in saltbush and lower circulating insulin and higher growth hormone of the S+B fed sheep compared to the control fed sheep. Further work is needed to determine if these beneficial improvements in carcass composition can be achieved without compromising animal production. The long term grazing of saltbush did not result in commercially desirable hot carcass weights unless the sheep were supplemented with a high energy source such as barley. The low growth rates are attributed to a decreased availability of energy substrates, low feed intake and increased energy output of sheep fed high salt diets. The low energy intake of the S+B fed sheep also resulted in an a significantly lower percentage of unsaturated fat and unchanged levels of saturated fat in the fat depots compared to the C treatment. Consumer taste tests conducted on meat from experiments in both chapter 4 and 6 indicated no difference between the treatments for any of the eating quality traits assessed. This can be considered a positive result as sheep can be finished on saltbush without any detriment to eating quality. High vitamin E levels in the meat may have also prevented the development of rancid flavours and aroma. It can be speculated that saltbush does not impart beneficial flavour and aroma volatiles as previously thought; instead the high vitamin E levels inhibit off-flavour and aroma development compared to meat from sheep grazed on dry pasture. The long term ingestion of saltbush also resulted in significantly lower urine specific gravity (USG), muscle dry matter and higher urine weights suggesting that the saltbush fed sheep had a better hydration status compared to control fed sheep. However, this finding did not correspond with higher hot carcass weight or dressing percentages. The increases in muscle fluid content of the saltbush fed sheep were attributed to changes in body composition. The saltbush fed sheep had a higher lean and lower fat content which corresponded with a greater body fluid content as found in the animal house study. Under conditions where the body composition of sheep remains the same, the use of short term strategic feeding of components of saltbush was investigated (mimicked in the form of salt and betaine) to reduce dehydration and subsequent reductions in carcass weight and dressing percentages (Chapter 7). Salt and or betaine were fed for 1 week either prior to a 48 h period of water deprivation or prior to 48 h commercial slaughter process where water was available in lairage from 24-48 h. Under both scenarios the diets did not result in improved dressing percentages, hot carcass weights, muscle dry matter or muscle weights. The ingestion of high salt diet prior to slaughter, did increase fluid retention in the extracellular spaces prior to slaughter however by 48 h both groups were at a similar physiological and therefore similar hydration status. Therefore similar levels of fluid were present in the muscles and no difference in carcass weight or dressing percentage could be expected. An important observation from the second experiment was that the high salt group drunk more water than the low salt fed sheep but the low salt group consumed fluid in lairage also. The low salt fed sheep may have been encouraged to drink water after observing the frequent drinking patterns of the high salt group. This thesis has also shown that saltbush contains high levels of vitamin E (alpha-tocopherol) (193 mg/kg dry matter). As a result the concentration of alpha-tocopherol in plasma, liver and muscle of the saltbush fed sheep was elevated compared to those grazing dry pasture. The high muscle concentrations of vitamin E in the saltbush-grazed sheep resulted in improved meat colour stability. The high vitamin E levels did not influence the drip and cooking loss of the meat despite a decrease in the muscle dry matter of the meat. The browning of meat and increased drip loss results in large losses to the meat industry due to value deterioration at the supermarket. There is also great potential for the high vitamin E content in saltbush to be used for the prevention of nutritional myopathy instead of using expensive and labour intensive synthetic supplements. In conclusion, this thesis has provided an insight into the carcass and eating quality of sheep grazed on saltbush based saline pasture systems. The most significant findings were that ingesting saltbush can reduce the carcass fat content, improve meat colour stability and not result in any detriment to eating quality. A potentially useful way to incorporate these results into an Australian farming system may be to use saltbush on a short term basis, not for the length of period grazed in this thesis. The short term use of saltbush should provide sufficient grazing time for an elevation of vitamin E levels in the muscle to improve meat colour stability, increase the amount of lean and decrease fat levels of a carcass all without changing eating quality and decreasing liveweight. Further work is needed to ensure that these benefits can be achieved without compromising animal production. The opportunity to utilise saltbush to produce leaner carcasses with better colour stability may encourage farmers to consider previously unproductive land planted to saltbush to be a highly useful enterprise.

Forage halophytes such as saltbush (Atriplex spp) are being widely used to revegetate Australian saline land and can also provide a medium quality fodder source. There is widespread anecdotal evidence that sheep grazing on saltbush are leaner, tastier and juicer. This thesis investigated the potential to produce a high quality carcass with improved eating quality from grazing sheep on saltbush on saline land. The first experimental chapter in this thesis details an animal house experiment investigating the carcass, eating and wool quality and physiological responses of sheep ingesting a 60:40 dried saltbush (Atriplex nummularia):barley grain (S+B), ration verses a 33:25:42 lupin grain:barley grain:oaten hay ration (Control, C) for 10 weeks prior to commercial slaughter (Chapter 4). Subsequently, two field experiments were conducted to examine the effects of grazing saltbush on saline land compared to dry senesced pasture on carcass and eating quality of lambs (Goomalling 2003) and hoggets (Wickepin 2004) (both chapter 6) for 14 weeks. Both chapters demonstrated that the ingestion of saltbush resulted in significantly less fat and in the 2 field experiments the ingestion of saltbush resulted in more lean on the carcass compared to sheep grazing a stubble/pasture (control) ration. These are positive findings for processors as costs of fat denudation are high so the lower the fat content and for farmers because less fat is deposited on the carcass per unit of liveweight gain. The decreased deposition of fat was attributed to the higher protein:energy ratio available for production, secondary compounds in saltbush and lower circulating insulin and higher growth hormone of the S+B fed sheep compared to the control fed sheep. Further work is needed to determine if these beneficial improvements in carcass composition can be achieved without compromising animal production. The long term grazing of saltbush did not result in commercially desirable hot carcass weights unless the sheep were supplemented with a high energy source such as barley. The low growth rates are attributed to a decreased availability of energy substrates, low feed intake and increased energy output of sheep fed high salt diets. The low energy intake of the S+B fed sheep also resulted in an a significantly lower percentage of unsaturated fat and unchanged levels of saturated fat in the fat depots compared to the C treatment. Consumer taste tests conducted on meat from experiments in both chapter 4 and 6 indicated no difference between the treatments for any of the eating quality traits assessed. This can be considered a positive result as sheep can be finished on saltbush without any detriment to eating quality. High vitamin E levels in the meat may have also prevented the development of rancid flavours and aroma. It can be speculated that saltbush does not impart beneficial flavour and aroma volatiles as previously thought; instead the high vitamin E levels inhibit off-flavour and aroma development compared to meat from sheep grazed on dry pasture. The long term ingestion of saltbush also resulted in significantly lower urine specific gravity (USG), muscle dry matter and higher urine weights suggesting that the saltbush fed sheep had a better hydration status compared to control fed sheep. However, this finding did not correspond with higher hot carcass weight or dressing percentages. The increases in muscle fluid content of the saltbush fed sheep were attributed to changes in body composition. The saltbush fed sheep had a higher lean and lower fat content which corresponded with a greater body fluid content as found in the animal house study. Under conditions where the body composition of sheep remains the same, the use of short term strategic feeding of components of saltbush was investigated (mimicked in the form of salt and betaine) to reduce dehydration and subsequent reductions in carcass weight and dressing percentages (Chapter 7). Salt and or betaine were fed for 1 week either prior to a 48 h period of water deprivation or prior to 48 h commercial slaughter process where water was available in lairage from 24-48 h. Under both scenarios the diets did not result in improved dressing percentages, hot carcass weights, muscle dry matter or muscle weights. The ingestion of high salt diet prior to slaughter, did increase fluid retention in the extracellular spaces prior to slaughter however by 48 h both groups were at a similar physiological and therefore similar hydration status. Therefore similar levels of fluid were present in the muscles and no difference in carcass weight or dressing percentage could be expected. An important observation from the second experiment was that the high salt group drunk more water than the low salt fed sheep but the low salt group consumed fluid in lairage also. The low salt fed sheep may have been encouraged to drink water after observing the frequent drinking patterns of the high salt group. This thesis has also shown that saltbush contains high levels of vitamin E (alpha-tocopherol) (193 mg/kg dry matter). As a result the concentration of alpha-tocopherol in plasma, liver and muscle of the saltbush fed sheep was elevated compared to those grazing dry pasture. The high muscle concentrations of vitamin E in the saltbush-grazed sheep resulted in improved meat colour stability. The high vitamin E levels did not influence the drip and cooking loss of the meat despite a decrease in the muscle dry matter of the meat. The browning of meat and increased drip loss results in large losses to the meat industry due to value deterioration at the supermarket. There is also great potential for the high vitamin E content in saltbush to be used for the prevention of nutritional myopathy instead of using expensive and labour intensive synthetic supplements. In conclusion, this thesis has provided an insight into the carcass and eating quality of sheep grazed on saltbush based saline pasture systems. The most significant findings were that ingesting saltbush can reduce the carcass fat content, improve meat colour stability and not result in any detriment to eating quality. A potentially useful way to incorporate these results into an Australian farming system may be to use saltbush on a short term basis, not for the length of period grazed in this thesis. The short term use of saltbush should provide sufficient grazing time for an elevation of vitamin E levels in the muscle to improve meat colour stability, increase the amount of lean and decrease fat levels of a carcass all without changing eating quality and decreasing liveweight. Further work is needed to ensure that these benefits can be achieved without compromising animal production. The opportunity to utilise saltbush to produce leaner carcasses with better colour stability may encourage farmers to consider previously unproductive land planted to saltbush to be a highly useful enterprise.

Cette these comporte deux objectifs : d'une part, on cherche a estimer le rendement de viande noble (filets et cuisses) d'un lot de carcasses a partir de l'outil de vision industrielle ; d'autre part, on cherche a detecter et identifier, grace a l'information couleur, les defauts d'aspect visibles apres la plumaison (hematomes, dechirures, griffures, etc. ). Ce projet s'articule donc autour de thematiques complexes : d'une part, l'analyse d'images de produits a morphologie fortement variable ; d'autre part, la mise en place d'un systeme de vision couleur capable d'apprecier des differences de couleurs relativement fines, afin de detecter les defauts d'aspect. Les travaux qui ont ete realises portent non seulement sur les aspects scientifiques du probleme mais aussi sur le plan technique, puisque cette these cifre (convention industrielle de formation par la recherche) s'inscrit dans la phase de transfert industriel du projet. La conception du poste de prise de vues est soumise a nombre important de contraintes : humidite des carcasses, uniformite d'eclairage sur un objet en relief, rendu de couleurs, environnement industriel, etc. Un logiciel de simulation d'eclairage a permis de specifier la geometrie du poste d'eclairage ; en outre, un processus d'etalonnage couleur garantit la stabilite des mesures effectuees sur l'image. L'estimation du rendement met en uvre des techniques statistiques couplees a des algorithmes d'analyse d'images dont le role est d'extraire des caracteristiques morphologiques de la carcasse. Les defauts d'aspect sont detectes par leur couleur. Les resultats de differentes methodes de detection ont ete compares objectivement, par rapport a une reference visuelle. Les methodes de detection et d'identification developpees au cours de cette these mettent en uvre des histogrammes couleur. Cette approche permet d'exploiter precisement l'information couleur tout en restant en accord avec les contraintes temps-reel liees au projet.

The effects of age and plane of nutrition on the body and carcass composition and mohair fibre yield and quality of British Angora wether goats slaughtered at six, 12, 18 and 24 months of age were investigated. Carcass yield, composition and conformation improved with increasing age and plane of nutrition. Greasy fleece weight also increased with increasing age and plane of nutrition but fibre quality declined since the increase in mass was achieved by means of increased fibre diameter with no effect of age or plane of nutrition on the fibre elongation rate. There was a constant relationship between the increase in fibre diameter with age and fleece mass which was not affected by plane of nutrition. Similarly there was no significant effect of plane of nutrition on the relationships between fibre diameter and the weight of various body and carcass components. A strong relationship between fibre diameter and the weight of fat in the body or carcass suggested that the increase in fibre diameter with age of the goat was influenced by cumulative feed intake rather than by fat-free body size. The allometric growth patterns of the body and carcass of the Angora goat conformed with the patterns established for other domestic species, with early maturity of the external offal and vital organs, later maturity of the carcass and body fat, and a centripetal pattern of development. There was no effect of plane of nutrition on the allometric growth patterns of the fat-free body or carcass, but decreasing the plane of nutrition resulted in a uniform retardation of all body parts and carcass tissues and a significant effect on the relative growth rate of body and carcass fat. Regression equations were formulated to predict the half carcass composition of Angora wether goats using sample joint dissection data. The most accurate predictions were achieved with data from the leg and the best end of neck combined in multiple regression equations. A second experiment to investigate the effects of long term undernutrition followed by realimentation on the growth rate and composition of empty body weight gain revealed no evidence of compensatory liveweight gain in the Angora goat.

Pig meat quality is determined by several parameters, such as lipid content, tenderness, water-holding capacity, pH, color and flavor, that affect consumers’ acceptance and technological properties of meat. Carcass quality parameters are important for the production of fresh and dry-cure high-quality products, in particular the fat deposition and the lean cut yield. The identification of genes and markers associated with meat and carcass quality traits is of prime interest, for the possibility of improving the traits by marker-assisted selection (MAS) schemes. Therefore, the aim of this thesis was to investigate seven candidate genes for meat and carcass quality traits in pigs. In particular, we focused on genes belonging to the family of the lipid droplet coat proteins perilipins (PLIN1 and PLIN2) and to the calpain/calpastatin system (CAST, CAPN1, CAPN3, CAPNS1) and on the gene encoding for PPARg-coactivator 1A (PPARGC1A). In general, the candidate genes investigation included the protein localization, the detection of polymorphisms, the association analysis with meat and carcass traits and the analysis of the expression level, in order to assess the involvement of the gene in pork quality. Some of the analyzed genes showed effects on various pork traits that are subject to selection in genetic improvement programs, suggesting a possible involvement of the genes in controlling the traits variability. In particular, significant association results have been obtained for PLIN2, CAST and PPARGC1A genes, that are worthwhile of further validation. The obtained results contribute to a better understanding of biological mechanisms important for pig production as well as for a possible use of pig as animal model for studies regarding obesity in humans.

Pig meat quality is determined by several parameters, such as lipid content, tenderness, water-holding capacity, pH, color and flavor, that affect consumers’ acceptance and technological properties of meat. Carcass quality parameters are important for the production of fresh and dry-cure high-quality products, in particular the fat deposition and the lean cut yield. The identification of genes and markers associated with meat and carcass quality traits is of prime interest, for the possibility of improving the traits by marker-assisted selection (MAS) schemes. Therefore, the aim of this thesis was to investigate seven candidate genes for meat and carcass quality traits in pigs. In particular, we focused on genes belonging to the family of the lipid droplet coat proteins perilipins (PLIN1 and PLIN2) and to the calpain/calpastatin system (CAST, CAPN1, CAPN3, CAPNS1) and on the gene encoding for PPARg-coactivator 1A (PPARGC1A). In general, the candidate genes investigation included the protein localization, the detection of polymorphisms, the association analysis with meat and carcass traits and the analysis of the expression level, in order to assess the involvement of the gene in pork quality. Some of the analyzed genes showed effects on various pork traits that are subject to selection in genetic improvement programs, suggesting a possible involvement of the genes in controlling the traits variability. In particular, significant association results have been obtained for PLIN2, CAST and PPARGC1A genes, that are worthwhile of further validation. The obtained results contribute to a better understanding of biological mechanisms important for pig production as well as for a possible use of pig as animal model for studies regarding obesity in humans.

Thesis (MSc)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: The purpose of this study was to evaluate the effects of age, sex, region and cropping methodology on the meat quality of impala. Forty impala were cropped during separate day and night operations at the Mara Agricultural Development Centre. Carcass pH45 (measured in M. longissimus dorsi 45 minutes post mortem) was higher in night cropped animals (6.67 ± 0.111; P<0.05) compared to the day cropped animals (6.55 ± 0.236). The ultimate carcass pH (pHu) of animals cropped at night was lower (5.39 ± 0.081; P<0.05) compared to those cropped in the day (5.45 ± 0.108). Non-linear regression analysis showed that the rate of pH decline of the night cropped animals was slower than that of the day cropped animals (P<0.05). The cooling rate of the M. longissimus dorsi was twice as fast in the night cropped group (P<0.05). Shear force values and drip losses of the night cropped animals were both lower (19.11 ± 5.675 g/mm2 and 2.93 ± 1.597% respectively; PO.OS) compared to those of day cropped animals (23.42 ± 8.128 g/mm2 and 4.15 ± 2.339%). The results indicate that nighttime cropping has a beneficial effect on certain meat quality parameters compared to daytime cropping. A second group of impala was sampled at the Musina Experimental Farm in the Limpopo Province of South Africa. Live weights of the Mara animals (50.23 ± 9.32 kg) were higher (P<0.05) than the Musina animals (44.25 ± 10.81 kg). Impala sampled at Mara had significantly higher dressing percentages than those at Musina (P<0.05). Impala ewes from both regions had a higher lipid content (P<0.05), but the sex of the animal had no effect on the remaining chemical parameters. The crude protein content of impala at Musina (24.88 ± 1.044%) was higher (P<0.05) than the Mara animals (23.80 ± 0.840%). Regional differences (P<0.05) were found in the amounts of phosphorous and calcium in the meat. Female animals at Mara showed higher proportions (P<0.05) of saturated (SFA), and mono-unsaturated fatty acids than the male animals. Males from both regions showed higher proportions (P<0.05) of poly-unsaturated fatty acids. Myristic, palmitic and stearic acid formed the greatest proportion of the SFA component for males and females from both regions. Samples of the M. semi-membranosus (SM), M. deltoideus (D), M. longissimus dorsi et laborum (LO), and M. psoas major (PS) were analysed for citrate synthase (CS) and phosphofructo-kinase activities. MHC distribution varied significantly between 0, SM and LD (PAFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die invloed van ouderdom, geslag, area, en uitdunmetodes op die vleiskwalitiet van rooibokke te evalueer. Veertig rooibokke is gedurende afsonderlike dag en nag uitdunningsoperasies by die Mara Landboukundige Ontwikkelings Sentrum geoes. Karkas pH45 (gemeet in die M. longissimus dorsi 45 minute post mortem) was hoër (P<0.05) in nag-geoesde diere (6.67 ± 0.11) in vergelyking met die dag-geoesde diere (6.55 ± 0.23). Die finale pH (pHu) van diere wat in die nag geoes is (5.39 ± 0.08) was laer (P<0.05) in vergelyking met die wat in die dag geoes is (5.45 ± 0.11). Nie-lineêre regressie analise toon dat die tempo van pH-daling van die nag-geoesde diere merkbaar stadiger was as die dag-geoesde diere (P<0.05). Die afkoelings tempo van die M. longissimus dorsi et lumborum was twee keer vinniger in die nag geoesde groep (P<0.05). Die gemiddelde skeurkragwaarde en drupverlies was beide laer (P<0.05) vir nag geoesde diere (respektiewelik 19.11 ± 5.67 g/mm2 en 2.93 ± 1.59%) in vergelyking met diere wat in die dag geoes is (23.42 ± 8.12 g/mm2 en 4.15 ± 2.33%). Die resultate toon dat nag-uitdunning 'n voordelige effek op vleiskwaliteit gehad het, in vergelyking met dag-uitdunning. 'n Tweede groep van rooibokke is gemonster by die Musina Eksperimentele plaas in die Limpopo Provinsie in Suid-Afrika. Die gewigte van die Mara diere (50.23 ± 9.32 kg) was hoër (P<0.05) as die van die Musina diere (44.25 ± 10.81 kg). Die Mara groep het hoër uitslag persentasies (P<0.05) gehad. Vroulike diere in beide areas het 'n hoër vet inhoud (P>O.05) gehad. Die ru-proteien inhoud van die Musina diere (24.88 ± 1.04%) was hoër (P<0.05) as die van die Mara diere (23.80 ± 0.84%). Area verskille (P<0.05) is gevind in die fosfaat en kalsium inhoud in die vleis. Vroulike diere by Mara het 'n hoër proporsie (P<0.05) van versadigde en mono-onversadige vetsure in die weefsel as manlike diere gehad. Manlike diere van beide areas het 'n hoër proporsie (P<0.05) van poli-onversadige vetsure (P<0.05) as die vroulike diere getoon. Miristien, palmitien en stearien suur was kwantitatief die belangrikste vetsure in manlike en vroulike diere van beide areas. Monsters van die M. semi-membranosus (SM), M. deltoideus (D), M. longissimus dorsi et laborum (LO), en M. psoas major (PS), van die rooibokkarkasse is ontleed vir sitraatsintase (SS) en fosfofruktokinase aktiwiteite (FFK). MSK verspreiding het merkbaar varieer tussen 0, SM en LO (P