Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Animal Science, 2005. / "March 2003" Includes bibliographical references (leaves 237-297).

Thesis (MMedVet. (Production Animal Studies)--University of Pretoria, 2002. / Includes bibliographical references. Also available in print format.

South Africans frequently consume red meat as part of their diet. However the nutrient content of South African sheep meat is derived from other countries. The Red Meat Industry considered it essential to have more reliable data and thus the nutrient content of A2 South African lamb was recently determined and published. This is the next phase of the study in which the right sides of C2 mutton carcasses were used to determine the nutrient and physical (carcass) composition of each raw cut as well as the whole carcass by calculation. Eighteen mutton carcasses of the most commonly consumed breeds, namely Dorper and Merino, in South Africa were selected. The carcasses were obtained from large abattoirs form three mutton producing regions in South Africa namely Ermelo, the Karoo and Kalahari. Chilled carcass sides were subdivided into ten primal cuts. Three cuts (shoulder, loin and leg) from the left side were cooked in order to determine the nutrient composition thereof. The cuts were dissected into meat which consists of muscle and intramuscular fat, intermuscular - plus subcutaneous fat and bone in order to determine the physical composition per cut and for the whole carcass. Meat compromise of 63.2% of the carcass, with bone contributing to 20.5% and fat to 16.9%. Results showed differences in the physical composition of South African C2 mutton as it contains on average 47% less fat and 19% more lean muscle, when compared to previous published composition data. Three cuts (shoulder, loin and leg) from the left side were cooked in order to determine the nutrient composition thereof. Cooking resulted in an increase in the protein and cholesterol concentrations of the cooked cuts. Iron content was higher in the cooked loin and leg but decreased in the cooked shoulder. According to nutrient density, a 100g edible portion of the leg, loin and shoulder have a nutrient density higher than one for protein, iron, zinc and vitamin B12 indicating that these cuts are a good source of these specific nutrients. A 100g edible portion of the loin cut contained higher fat quantities than the cooked shoulder and leg cuts. The loin cut also had a higher cholesterol content at 70.8mg compared the 58.5mg cholesterol content in the shoulder and 57.9mg in the leg cut. However, these values were calculated with all associated subcutaneous fat and it is known that many consumers trim on plate, especially the loin cut. Considering the fact that significant differences were apparent between the current study and previous data derived from other countries, it emphasizes the importance of determining the nutrient composition of South African food products in order to increase the validity of the SA food composition tables. Food-based approaches targeting the relief of micronutrient deficiency usually encourage the consumption of animal foods together with the consumption of green leafy vegetables (GLV). The inclusion of GLV and red meat, two micronutrient rich foods, can be a strategy based on mutual supplementation to combat nutritional deficiencies as it has the potential to alleviate numerous micronutrient deficiencies including iron and vitamin A deficiency. / Dissertation (MSc)--University of Pretoria, 2009. / Food Science / unrestricted

Se estudió el efecto de la suplementación energética en la dieta de engorde de corderos sobre parámetros de crecimiento animal, presentación de sus carcasas y ciertas propiedades nutracéuticas de la carne. Dos grupos de 24 corderos, INTA-601 (IN) y Merino (ME), de 20,7 ± 1,6 kg de peso vivo (PV) fueron divididos en tres grupos y alojados en bretes individuales luego del destete durante 49 días de experimentación. Tres niveles de suplementación energética fueron comparados con ocho repeticiones por tratamiento: el grupo control (CTR) recibió heno de alfalfa ad libitum (PB=13,6%, FDN=51,1% y EM= 2,32 Mcal/kgMS), los grupos S1 y S2 recibieron adicionalmente 0,5 y 1% del peso vivo como grano de maíz entero (EM= 3,02 Mcal/kgMS), respectivamente. Luego de 7 semanas de confinamiento los corderos fueron sacrificados, al cabo de 24 hs post-mortem se realizó morfometría y tipificación de carcasas. Se determinó la composición tisular de la espalda izquierda. Sub-muestras del Longissimus dorsi fueron colectadas para determinación de calidad de carne. La adición de concentrado energético en la dieta incrementó el consumo total de materia seca (CMS), 79,2; 84,5 y 84,1 gMS/kgPV0,75 para los grupos CTR, S1 y S2 respectivamente. El genotipo IN tuvo mayor CMS total, 87,0 versus 78,2 gMS/kgPV0,75 en el ME. El CMS de heno disminuyó con la adición de concentrado. La ganancia diaria de peso (GDP) fue mejorada con ambos niveles de suplementación con valores de 0,151; 0,193 y 0,218 kg/d (CTR, S1 y S2 respectivamente) al igual que la eficiencia de conversión alimenticia (ECA) sin diferenciarse entre niveles de suplementación: 6,51; 5,42 y 4,88 (CTR, S1 y S2 respectivamente). El genotipo IN tuvo mayor GDP, 0,218 versus 0,156 kg/d y mejor ECA, 4,93 versus 6,28. Los pesos al sacrificio, de carcasa caliente, de carcasa fría y rendimiento se incrementaron con la adición de concentrado en la dieta. El genotipo IN mostró parámetros de carcasa y rendimiento superiores al ME. El grado de terminación y conformación de carcasas, la compacidad de carcasa y compacidad de pierna se incrementaron con el aporte de suplemento en la ración. El genotipo IN tuvo mayor compacidad de carcasa y pierna, y mayores índices de magro y de carnosidad. La proporción de ácido linoleico conjugado (CLA) se incrementó un 38% entre S2, respecto el grupo S1. Su precursor, el ácido vaccénico, incrementó un 125% su porcentaje en el grupo S2, solamente en el genotipo IN. Las relaciones n-6/n-3 y AGPI/AGS no fueron afectadas por el tratamiento y genotipo, sin embargo presentaron valores considerados deseables para la salud humana. El genotipo IN tuvo menor AGS y mayor AGMI, sin afectar la relación AGPI/AGS. Incrementando la concentración energética en la ración, fue posible obtener carcasas más pesadas, mejor conformadas y terminadas, sin aparentes detrimentos en la calidad de carne. El nivel de suplementación recomendable fue el 1%PV en el presente estudio, para ambos genotipos. El genotipo IN manifestó su biotipo carnicero, con carcasas magras y mejor conformadas. El genotipo ME demostró poseer una calidad de carcasa aceptable. El perfil lipídico del músculo Longissimus fue mejorado por la suplementación en relación al contenido de CLA y de su precursor, el ácido vaccénico. En resumen, el genotipo animal manifestó su influencia en la calidad de la carcasa principalmente, mientras que la suplementación energética incrementó los parámetros de crecimiento, mejorando la presentación de las carcasas sin afectar la calidad intrínseca de la carne ovina. / Was investigated the effects of energy supplementation of fattening lambs on growth parameters, carcass presentation and nutraceutical properties of meat. Two groups of 24 lambs, INTA-601 (IN) and Merino (MER) of 20.7 ± 1.6 kg average liveweight (LW) were divided into three groups and housed in individual pens for 49 days after weaning. Three energy supplementation levels were compared with eight replicates per treatment. A control group (CTR) received alfalfa hay ad libitum (CP = 13.6%, NDF = 51.1% and ME = 2,32 Mcal / kg DM), groups S1 and S2 were additionally given 0.5 and 1% of liveweight as whole corn grain, respectively. After 7 confinement weeks, lambs were slaughtered, and 24 hours post-mortem carcass morphometry measurements and carcass classification were carried out. Left shoulder tissue composition was determined. Longissimus dorsi sub-samples were collected for meat quality determination. Energetic concentrate addition to the diet increased total dry matter intake (DMI), 79.2, 84.5 and 84.1 gDM/kgLW0,75 to CTR, S1 and S2 groups, respectively. IN genotype had higher total DMI, 87.0 versus 78.2 gDM/kgLW0,75 . Hay DMI decreased with concentrate addition. Average daily gain (ADG) was improved with each supplementation level with 0.151, 0.193 and 0.218 kg/d values to CTR, S1 and S2, respectively as well as feed conversion efficiency (FCE): 6.51, 5.42 and 4.88 for CTR, S1 and S2 respectively, without differentiating between supplementation levels. IN genotype had higher ADG, 0.218 versus 0.156 kg/d, and better FCE, 4.93 versus 6.28. Slaughter weight, hot and cold carcass weight and yield increased with concentrate addition in diet. IN genotype had higher carcass and yield parameters. Carcass fattening score, carcass conformation score, carcass compactness and leg compactness increased with concentrate addition to the diet. IN genotype had more carcass and leg compactness, lean and meaty rate. Conjugated linoleic acid (CLA) proportion increased by 38% between S2 group, to S1 group. Its precursor, vaccenic acid, increased 125% their percentaje in S2 group, only in IN genotype. n-6/n-3 and PUFA/SFA ratios were not affected by treatment or genotype, however values were considered desirable for human health. IN genotype had lower SFA proportion and more MUFA proportion, without affecting PUFA/SFA ratio. Increasing the energetic concentration in diet, it was possible to obtain heavier carcasses, better shaped and finished carcasses with no apparent detriment in meat quality. The supplementation level recommended was 1% LW in the present study, for both genotypes. IN genotype expressed meaty biotype, lean carcasses and better conformation. ME genotype proved to have an acceptable carcass quality. Longissimus lipid profile was improved by supplementation in relation to CLA and its precursor, vaccenic acid. In summary, the animal genotype indicated its influence on carcass quality, while energy supplementation increased growth parameters, improving carcass presentation without affecting the quality of sheep meat.

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The aim of the study was to determine the effect of increasing levels of Maize silage in finishing diets for Merino lambs on their feed intake, production performance, feed conversion ratio, digestibility and meat quality. Concerns exist regarding the intake of high moisture and fibre containing silage in sheep due to the physical fill effect thereof. To determine the efficiency of silage as feed ingredient for sheep, maize was cut at 27% dry matter (DM), compacted into 220 litre plastic drums, sealed and left to ferment for 60 days. The silage produced was analysed for fermentation end products and the nutritive value determined. The silage produced had an optimum pH, starch and water soluble carbohydrate (WSC) content. The crude protein (CP) content (112.2 g/kg DM) was higher than expected. Four diets containing, on a dry matter (DM) basis either, 0, 20, 50 or 70% maize silage was formulated on an iso-nutrient basis with exception of neutral detergent fibre (NDF). The aim was to establish the effect of increasing levels of silage on animal production with regard to dry matter intake, growth, digestibility and meat quality. Diets were formulated on an iso-nutrient basis to match the 70% silage diet and therefore had relatively low specifications due to the high inclusion of silage from the 70% silage diet. A growth study and an in vivo and in vitro digestibility study were conducted to determine the effect of the different diets on feedlot sheep production. Meat quality was also determined to establish whether the experimental diets had an effect on meat quality. Forty lambs in a completely randomised block design, with four treatments, were used in a 60-day finishing study. The dry matter intake (DMI) of lambs decreased as silage inclusion increased above the 20% silage inclusion level. At the 20% inclusion rate, the feed intake of the animals was stimulated. This resulted in significant differences found between the cumulative intake of the low and the high silage diets. Feed conversion ratio (FCR) was poorer, however, for the control and 20% silage diets. The poor FCR most likely was related to the quality of the feed ingredients used in the formulation of the control feed and the concentrate in the 20% silage diet rather than the silage itself. Significant differences were also found in the dressing percentage of the slaughtered animals where the 20 and 50% silage diets had a higher dressing percentage than the control and 70% silage diets. It was concluded that silage can be successfully incorporated into sheep diets, especially at low levels where its inclusion stimulates intake. Eight animals per group were used in an in vivo digestibility study to determine the apparent digestibility of the experimental diets. Feed, faeces and urine samples collected during the trial period were analysed for the respective nutrients. The 20% diet, even though having the best overall apparent digestibility, did not result in better production responses. Lambs on the 20% silage diet had the highest daily DM intake, which resulted in them having the highest energy intake. There were no differences in total energy excreted between the silage-based diets. This resulted in the 20% silage diet also having the best energy retention. Nitrogen retention was the highest for the control and 20% silage diets. This can be ascribed to the low quality of the concentrate part of the diet. The 20% silage diet, as previously stated, had the highest apparent DM and organic matter (OM) digestibility, while the control diet showed the lowest overall nutrient digestibility. The low nutrient digestibility of the control diet can be ascribed to the relatively poor quality ingredients used. There were no differences in the crude protein (CP) digestibility between the control and the 20% diet. Both proved to be higher than the CP digestibility of the 50 and 70% silage diet. As the neutral detergent insoluble nitrogen (NDIN) was higher for the 50 and 70% diets, this observation was not surprising. Fibre content of the silage-based diets increased as the inclusion level of the silage increased, which resulted in a decrease in overall fibre digestion. Three cannulated sheep were adapted on each experimental diet for two weeks before rumen fluid was collected for the in vitro digestibility study. No differences between the silage based diets were found for in vitro true digestibility (IVTD). The IVTD of the 20, 50 and 70% diets were higher, however, than the IVTD of the control diet confirming earlier observations on the choice of ingredients used in the control diet to formulate iso-nutrient diets. Degradability coefficients were determined for the DM and NDF fractions of the different experimental diets and fitted to the non-linear model; p = a + b (1 – e-ct). The amount of DM that disappeared in a certain time (t) is represented by p. Constant a represents the fraction that was rapidly soluble, b represents the potential degradable fraction and c is the rate at which b was degraded. There were no differences between experimental diets for the rapidly soluble fraction. The silage-based diets had a higher potential degradable fraction (b) but did not differ in the degradability rate (c) from the control diet. Silage-based diets had higher overall effective degradability than the control but did not differ between one another. Constant a was not determined for NDF degradability since the NDF fraction did not have a rapidly soluble fraction. The control diet had the lowest potential degradable NDF fraction with the rate also being lower than the silage based diets. Effective NDF degradability was highest for the 50% silage diet. Lambs used in the finishing study were slaughtered and meat samples taken for meat quality tests. The pH, colour, drip loss, cooking loss, shear force and fatty acid composition were determined on the Longissimus dorsi samples collected at Roelcor (Malmesbury, Western Cape, South Africa). Proximate analysis was also conducted on the meat samples. The experimental diets did not have a significant effect on the proximate chemical composition of the meat. Colour differences were found; however no clear pattern could be established. There were no differences in fatty acid composition. It can be concluded that up to 70% maize silage can be included in the finishing diets of Merino lambs with no adverse effects on the meat quality. The study showed that 20% maize silage can be included in the finishing diets of Merino lambs without negatively affecting intake, production, digestibility or meat quality. Future research is needed to optimise the 20% silage diet, however, and to again look at the effect that it will have on animal production, including the effect thereof on total methane emissions. / AFRIKAANSE OPSOMMING: Die doel van die studie was om te bepaal of mielie kuilvoer doeltreffend gebruik kan word as ‘n komponent in die afronding van Merino lammers. Gedurende die proses is mielies gesny teen 27% droë materiaal (DM), en saamgepers in 220 liter plastiek dromme. Dit is toegelaat om te fermenter vir 60 dae. Die kuilvoer wat daaruit geproduseer is, is geanaliseer vir fermentasie eindprodukte, en die voedingstofwaarde is bepaal. Vier diëte met onderskeidelik 0 (kontrole), 20, 50 en 70% kuilvoer is geformuleer op ‘n iso-nutriëntbasis met die uitsondering van vesel (NDF). ‘n Groeistudie, tesame met ‘n in vivo en in vitro verteerbaarheidstudie is uitgevoer om die effek van die verskillende diëte op diere produksie te toets. Vleiskwaliteit toetse is ook gedoen om te kyk of die verskillende diëte ‘n effek op vleiskwaliteit het. Veertig lammers, in ‘n ewekeurige blokontwerp, is gebruik in ‘n 60 dae afrondingstudie. Dit is opgemerk dat die DM inname (DMI) afgeneem het soos die kuilvoer insluiting bo die 20% vlak toegneem het. By die 20% insluitingskoers, is voerinname by die diere gestimuleer. Dit het veroorsaak dat beduidende verskille gevind is tussen die kumulatiewe inname van die lae en die hoë kuilvoer diëte. Die voeromsetkoers (VOK) was egter hoër vir die kontrole en 20% kuilvoer diëte. Beduidende verskille is ook gevind in die uitslagpersentasie van die diere, waar die 20% en 50% kuilvoer diëte ‘n hoër uitslagpersentasie as die kontrole en 70% kuilvoer diëte gehad het. Agt diere is per groep gebruik in ‘n in vivo verteerbaarheidstudie om die skynbare verteerbaarheid van die eksperimentele diëte te toets. Voer, feses en urien monsters is gedurende die proefperiode ingesamel en geanaliseer. Die 20% kuilvoer dieet het die hoogste DM en organiese materiaal skynbare verteerbaarheid teenoor die kontrole diet wat die laagste gehad het. Daar was geen verskille in die ru- proteien (RP) verteerbaarheid van die kontrole en 20% kuilvoer diet nie. Beide was hoër as die RP verteerbaarheid van die 50% en 70% kuilvoer dieet. Die veselinhoud van die kuilvoergebasseerde diëte het toegeneem soos die insluitingsvlak van die kuilvoer toegeneem het, wat ‘n afname in veselvertering veroorsaak het. Lammers op die 20% kuilvoer dieet het die hoogste daaglikse DM inname gehad, wat die hoogste energie inname tot gevolg gehad het. Daar was geen verskille in die totale energie inname van die kuilvoergebasseerde diëte – dit het veroorsaak dat die 20% kuilvoer dieet ook die beste energie retensie gehad het. Stikstof retensie was die hoogste vir die kontrole en 20% kuilvoer dieet. Drie gekannuleerde skape is vir twee weke op elke eksperimentele dieet aangepas voordat rumenvloeistof ingesamel is vir die in vitro verteerbaarheidstudie. Geen verskille is gevind vir die in vitro ware verteerbaarheid (IVWV) tussen die kuilvoergebasseerde diëte nie. Hulle was egter hoër as die IVWV van die kontrole dieet. Degradeerbaarheid koëffisiënte is bepaal vir die DM en NDF fraksies van die verskillende eksperimentele diëte en is gepas in die model p = a + b (1 – e-ct). Die hoeveelheid DM wat verdwyn het binne ‘n sekere tyd (t) word voorgestel deur p. Die konstante a verteenwoordig die fraksie wat vinnig oplosbaar is, b verteenwoordig die potensieel degradeerbare fraksie en c is die koers waarteen b gedegradeer is. Konstante a is nie bepaal vir die NDF degradeerbaarheid nie, aangesien die NDF fraksie nie ‘n vinnig oplosbare fraksie gehad het nie. Daar was geen verskille in die vinnig oplosbare fraksie tussen eksperimentele diete nie. Kuilvoer gebasseerde diete het ‘n hoër potensieel degradeerbare fraksie gehad, maar daar was geen verskille in koers van degradering nie. Die kuilvoergebasseerde diëte het ‘n hoër DM effektiewe degradeerbaarheid as die kontrole dieet. Effektiewe NDF degradeerbaarheid was die hoogste vir die 50% kuilvoer dieet. Lammers in die studie gebruik is geslag en vleismonsters is geneem vir vleiskwaliteit toetse, insluitende pH, kleur, drupverlies, kookverlies en taaiheid. Proksimale analise is ook uitgevoer op die vleismonsters. Die eksperimentele diëte het nie ‘n beduidende effek op die proksimale chemiese samestelling van die vleis gehad nie. Kleur verskille is wel gevind, maar geen duidelike patroon kon vasgestel word nie. Daar was geen verskille in die vetsuur samestelling nie. Daar kan dus tot die gevolgtrekking gekom word dat mielie kuilvoer ingesluit kan word in die afrondingsdiëte van Merino lammers, tot by 70%, sonder enige negatiewe effekte op die vleiskwaliteit. Daar is tot die gevolgtrekking gekom dat mielie kuilvoer suksesvol geïnkorporeer kan word in skaapdiëte, veral teen lae vlakke (20%) waar die gebruik nie net inname stimuleer nie, maar ook geen negatiewe effekte het op produksie en verteerbaarheid nie. / Dr. Francois van de Vyver, Cape Wools and NWGA for providing funding in the form of post graduate bursaries

Thesis (MScAgric)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Genetic (co)variances for body weight, clean fleece weight and fibre diameter were estimated for the South African Dohne Merino using data transformed as proportions of contemporary group means. The data analysed included body weight, clean fleece weight and fibre diameter records for 282 513 animals, evaluated between 1992 and 2011. There were 5 698 sires, 105 886 dams and 6 291 contemporary groups in the data. A three-trait animal model was fitted, where the random variables were the direct additive genetic effects, as well as the sire-flock-season (SFS) interaction, while the fixed effects included contemporary groups (FYSSM) (6 291 classes), birth status (single, twins or triplets), age of dam (1 to 3 years), which was plotted as a linear regression as well as age at performance measurement, which was fitted as a polynomial. The direct heritability estimates (SE) for body weight, clean fleece weight and fibre diameter were 0.265 (0.005), 0.210 (0.004) and 0.437 (0.005), respectively. Genetic correlations for body weight with clean fleece weight and fibre diameter were 0.035 (0.015) and 0.139 (0.011), respectively, while the genetic correlation between clean fleece weight and fibre diameter was 0.169 (0.012). Body weight had phenotypic correlations of 0.327 (0.002) and 0.150 (0.002), respectively, with clean fleece weight and fibre diameter, which had a phenotypic correlation of 0.190 (0.002) with clean fleece weight. The moderate to high heritability estimates suggests that there is substantial genetic variation, which may result in genetic improvement if selection is applied on these traits. Genetic correlations were generally low, suggesting that progress in all these traits was possible in a scientific selection program. Genetic trends derived during the study supported the contention that genetic progress in all traits was attainable in a well-constructed breeding programme. Transformation of the data to percentages of contemporary groups resulted in adjustments to breeding values. The breeding values for sires originating from flocks maintained in limiting environments (Low group; 180 sires) were adjusted upwards, while those of sires originating from a non-limiting production environment (High group; 146 sires) were adjusted downwards. These effects were markedly obvious for the quantitative traits (body weight and clean fleece weight), but to a much lesser extent for fibre diameter. This transformation resulted in the genetic trends for the Low groups being adjusted to be comparable to those in the High group for body weight and Fibre diameter. It was concluded that sire breeding values derived from transformed data would be more robust across the typical diverse environments supporting local Dohne Merino production. The genetic value of animals entering the recorded population from a commercial base (F4 animals) was below the fully recorded part of the population. The inclusion of phantom parent groups in the genetic analysis rendered genetic trends in F4 animals comparable to that of the pedigreed portion of animals in the analyses. It was concluded that animals from a commercial base (which are alleged to have advantages in terms of fitness and robustness) were more likely to perform satisfactorily for selection with the inclusion of phantom groups than without it. It was recommended that data in the national Dohne Merino analysis be transformed proportion of contemporary group means to account for heterogeneous contemporary group variances. Phantom parent groups should also be applied to the analysis to increase the probability of those animals entering the breeding flock from a commercial base being selected. / AFRIKAANSE OPSOMMING: Genetiese kovariansies vir liggaamgewig, skoonvaggewig en veseldikte is vir die SA Dohne Merino bevolking in Suid-Afrika beraam nadat data getransformeer as ‘n proporsie van die kontemporêre groep gemiddelddes uitgedruk is. Die data het rekords in van liggaamsgewig, skoonvaggewig en veseldikte van 282 513 diere oor die tydperk van 1992 tot 2011 ingesluit. Die data sluit rekords van 5 698 vaars, 105 886 moers en 6 291 kontemporêre groepe in. 'n Meer-eienskapdieremodel met 'n additiewe diere-effekte sowel as 'n vaar-kudde-seisoen (SFS) interaksie is as ewekansige effekte gemodelleer, bykomstig tot die vaste effekte van kontemporêre groep (FYSSM) (6 291 klasse), geboortestatus (enkelling, tweeling of drieling), ouderdom van moer (1 tot 3 jaar) gepas as 'n lineêre regressive, sowel as ouderdom by prestasie meting as ‘n polinoom gepas. Die beraamde direkte oorerflikheid (SF) van liggaamgewig, skoonvaggewig en veseldikte van die meereienskap dieremodel was onderskeidelik 0,265 (0,005), 0,210 (0,004) en 0,437 (0,005). Die genetiese korrelasies van liggaamsgewig met skoonvaggewig en veseldikte was 0,035 (0.015) en 0,139 (0.011) onderskeidelik, terwyl die genetiese korrelasie tussen skoonvaggewig en veseldikte 0,169 (0.012) beloop het. Liggaamsgewig het onderskeie fenotipiese korrelasies van 0,327 (0.002) en 0.150 (0.002) met skoonvaggewig en veseldikte gehad, terwyl skoonvaggewig ‘n fenotipiese korrelasie van 0.190 (0.002) met veseldikte gehad het. Die medium tot hoë oorerflikheidhede dui daarop dat daar aansienlike genetiese variasie voorkom, wat kan aanleiding gee tot genetiese vordering as seleksie op die eienskappe toegepas word. Genetiese korrelasies was oor die algemeen laag wat daarop dui dat vordering in al die eienskappe deur ‘n wetenskaplike seleksie program moontlik is. Die aanspraak is deur genetiese tendense in die studie bevestig. Die transformasie van data na proporsies van kontemporêre groep gemiddeldes het daartoe gelei dat teelwaardes aangepas word. Die teelwaardes van vaars uit kuddes met ‘n omgewing wat beperk word (Lae groep:180 vaars), is opwaarts aangepas. Daarenteen is vaars uit 'n nie-beperkende produksie omgewing (Hoë groep:146 vaars) se teelwaardes afwaarts aangepas. Hierdie effekte was veral ooglopend vir die kwantitatiewe eienskappe, liggaamgewig en skoonvaggewig, maar tot 'n mindere mate vir veseldikte. Die transformasie het daartoe gelei dat die genetiese tendense for die Lae groep aangepas word om vergelykbaar te wees met die Hoë groep vir liggaamsgewig en skoonvaggewig. Die gevolgtrekking was gemaak dat meer toepaslike vaar teelwaardes, bereken vanaf getransformeerde data, verkry word vir regoor die diverse omgewings wat produksie van plaaslike Dohne Merinos ondersteun. Die genetiese waarde van diere wat die aangetekende populasie uit ‘n kommersiële agtergrond (F4 diere) binnekom was laer as die volledig aangetekende gedeelte van die populasie. Die insluiting van skimgroepe in die genetiese ontleding het tot genetiese tendense gelei wat die F4 diere vergelykbaar gemaak het met diere in die ontleding wat wel stamboekinligting het. Die gevolgtrekking is gemaak dat diere van ‘n kommersiële agtergrond (wat aanvaar word om voordele in te hou in terme van fiksheid en robuustheid) meer geredelik geselekteer sal word vir die stoet met die insluiting van skimgroepe as daarsonder. Dit word aanbeveel dat die data in die Nasionale Dohne Merino na proporsies van die kontemporêre groepgemiddeldes getrensformeer word om vir heterogene kontemporêre groep variansies voorsiening te maak. Skimgroepe moet ook gepas word in die ontleding om die waarskynlikheid te verhoog dat diere vanuit 'n kommersiële basis, ook geselekteer sal word.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The application of assisted reproductive biotechnologies in sheep flocks is hampered by the susceptability of ovine sperm to cryodamage. There is still considerable scope in the improvement of cryopreservation protocols for ovine sperm to minimize the degree of damage to sperm during the cryopreservation process. Pre-cryopreservation processing has a definite effect on the survivability, motility, and fertilizing ability of sperm. Little information is however available on the potential contribution of the genetic make-up of rams, divergently selected for fecundity, on the ability of sperm to offer resistance to the damage caused by cooling, cryopreservation and thawing. The study aimed to investigate the influence of genetic selection for prolificacy (i.e. High Merino Line and Low Merino Line in terms of fecundity) on the ability of ovine sperm to offer resistance to cryodamage. The study investigated the effect of pre-cryopreservation processing by comparing motility and morphometry traits recorded for fresh- and post-thaw Merino ejaculated and epididymal sperm samples obtained form the High and Low lines, respectively. The effect of different sperm concentrations, equilibration periods and the addition or omission of seminal plasma from cryopreserved samples on the viability and morphometrical traits were also investigated. Ejaculate samples were collected by means of the artificial vagina (AV) method from 8 High Line rams and 7 Low Line rams. Epididymal samples were collected from 6 rams of each of the High and Low lines respectively, by recovering the epididymal sperm via aspiration from the cauda epididymides post mortem. Ejaculate samples were subjected to macroscopic and microscopic evaluation, and epididymal samples only to microscopic evaluation, for which the Sperm Class Analyzer® program was used for the evaluation of motility and morphometric measurements. Sperm motility recordings were captured at 100 frames per second. From findings of the study, it was concluded that genotype had no positive influence on the conception rate of the ewes mated to the High or Low Line rams, even though the rams from the two lines differed significantly in terms of their serving capacity. When sperm morphometry was evaluated for fresh ejaculate samples, the two lines differed significantly in terms of the morphometric traits elongation and ellipticity. Epididymal and ejaculated sperm obtained from Low Line rams had broader and rounder heads, compared to sperm obtained from High Line rams. When morphometry was assessed for sperm samples between the two methods of sperm recovery (collected with an AV or recovery via aspiration from the cauda epididymides of sacrificed rams), no morphometrical differences were observed. Significant differences were reported for the majority of the sperm motility traits (i.e. percentage motile, rapid-, medium-, slow swimming, curvilinear velocity (VCL), straight line velocity (VSL), average path velocity (VAP), and amplitude of the lateral head displacement (ALH)) recorded for ejaculated and epididymal sperm. The motility traits ALH and beat-cross frequency (BCF) analysed for epididymal sperm differed significantly between the two lines. When epididymal sperm were evaluated post-thaw, it became evident that the sperm obtained from the High Line rams had a larger acrosome surface cover when compared to that of the Low Line ram sperm. The addition of seminal plasma to epididymal samples did not result in an improvement of the preservation of sperm motility. It is known from the literature that cryopreservation causes a decrease in sperm head size. Head width was unaffected by cryopreservation with the addition of seminal plasma in this study, indicating a potential benefit with the use of seminal plasma in the cryopreservation protocol of epididymal ram sperm. The study compared two pre-processing techniques, i.e. the more time consuming swim-up technique (SUT) with a more time-efficient ‘flush technique’ (FT) to optimize the pre-processing protocol for motility assessment of sperm samples before cryopreservation of ram sperm. Comparison of the SUT and FT indicated that almost all of the motility parameters measured using the FT compared favourably with those obtained using the SUT. The results indicated that the FT can be used a more time-efficient technique to use for determining the motility of a sperm sample prior to cryopreservation. In conclusion, line differences associated with reproduction were observed in terms of the serving capacity of the rams, with selection for fecundity influencing the morphometric traits elongation and ellipticity for sperm obtained from the two lines. Future studies should be aimed at investigating morphometric traits of ovine sperm, to correlate it with fertilizing ability of sperm post-thaw and ensure optimal cryopreservation processing. / AFRIKAANSE OPSOMMING: Die toepassing van ondersteunende reproduksie tegnieke in skaaptroppe word bemoeilik deur die onvermoë van ram sperme om weerstand teen bevriesingskade te bied. Daar is nog baie ruimte vir die verbetering van die bevriesingsprotokolle vir skaap sperm om die omvang van bevriesingskade te verminder. Voor-bevriesing verwerking het dan 'n besliste uitwerking op die oorlewing, beweeglikheid en bevrugtingsvermoë, van skaap sperme. Min inligting is beskikbaar oor die potensiële bydrae van die genetiese samestelling van ramme wat uiteenlopend op grond van vrugbaarheid geselekteer is, op die vermoë van skaap sperme om weerstand te bied teen die skade wat deur verkoeling, diepbevriesing en ontdooiing, veroorsaak word. Die doelwit van die studie was om die invloed van genetiese seleksie vir fekunditeit (d.i. Hoë Merino Lyn en Lae Merino Lyn in terme van fekunditeit) op die vermoë van skaap sperme om weerstand teen bevriesingskade te bied, te ondersoek. Die studie het getoets wat die bevriesing proses se effek op epididimale sperme is, deur sperm motiliteit en -morfometrie te vergelyk tussen vars gekollekteerde sperme en sperm monsters na ontdooiing. Die effek van verskillende sperm konsentrasies, ekwilibrasie tydperke en die byvoeging of uitsluiting van seminale plasma op die lewensvatbaarheid en morfometriese eienskappe van Merino ramsperme is ondersoek in die studie. Geëjakuleerde monsters is versamel met behulp van 'n kunsmatige vagina (AV) van 8 Hoë Lyn en 7 Lae Lyn ramme. Epididimale monsters is verkry van 6 ramme van elk van die Hoë en Lae Lyne, deur middel van aspirasie van die sperme uit die cauda epididimii nadoods. Geëjakuleerde sperm monsters is met behulp van makroskopiese en mikroskopiese metodes geëvalueer, en epididimale sperm monsters slegs mikroskopies geëvalueer, met behulp van die Sperm Class Analyzer® program wat vir die evaluasie van beweeglikheid en morfometriese afmetings gebruik is. Sperm beweeglikheids opnames is opgeneem teen 100 raampies per sekonde. Die resultate van die studie het aangedui dat genotipe geen effek het op besetting van die ooie gepaar met die Hoë of Lae Lyn ramme gehad het nie, terwyl die dekvermoë aansienlik tussen ramme van die twee lyne verskil het. Wanneer die morfometriese eienskappe van vars geëjakuleerde sperme vergelyk was, het die lyne beduidend in terme van die morfometriese eienskappe van verlenging (elongation) en elliptisiteit verskil het. Die epididimale en geëjakuleerde sperme verkry vanaf die Lae Lyn ramme het ʼn breër en ronder kopvorm getoon as sperme wat verkry is van die Hoë Lyn ramme. Wanneer die morfometriese eienskappe van sperme versamel met die twee verskillende metodes (d.i. kunsmatige vagina of aspirasie vanuit die cauda epididimides) vergelyk was, is geen morfometriese verskille waargeneem nie. Die meeste sperm beweeglikheidseienskappe (d.i. persentasie beweeglike, vinnig-, medium- en stadig-swemmende sperme, VCL, VSL, VAP en ALH) van geëjakuleerde en epididimale sperme het verskil. Die beweeglikheidseienskappe amplitude van die laterale verplasing van die spermkop (ALH) en frekwensie waarmee sperm sy eie pad kruis (BCF), soos bepaal vir epididimale sperme, het beduidend tussen die twee lyne verskil. Met die evaluering van epididimale sperme na ontdooiing was dit duidelik dat sperme verkry van die Hoë Lyn ramme 'n groter mate van akrosoom-oppervlak gehad het, in vergelyking met sperme van die Lae Lyn ramme. Die byvoeging van seminale plasma by epididimale monsters het nie bygedra tot 'n verbetering van spermbeweeglikheid nie. Bestaande literatuur dui aan dat diepbevriesing 'n afname in die kopgrootte van sperme veroorsaak. In hierdie studie het die byvoeging van seminale plasma ʼn verandering in kopgrootte voorkom, wat dui op ʼn potensiële voordeel om seminale plasma in die bevriesingsprotokol van epididimale ramsperme in te sluit. Die studie het twee beweeglikheid bepalingstegnieke vergelyk om te bepaal of die tydrowende “opswem” tegniek (SUT) vervang kan word met 'n meer tyd-doeltreffende "spoel tegniek” (FT) in die voorbevriesing verwerking protokolle van ram sperme. Vergelyking van die twee tegnieke het aangedui dat die meeste van die kinematiese eienskappe van die FT gunstig met die waardes soos verkry met die SUT, vergelyk het. Resultate het getoon dat die FT parameters goed vergelyk met die beweeglikheid parameters van die SUT, dus kan dit aangeneem word dat die FT ʼn meer tyd-doeltreffende tegniek is wat vergelykbare sperm beweeglikheidsinligting oor skaap sperm monsters voor bevriesing sal verskaf. In samevatting is verskille in terme van die dekvermoë en op morfometriese vlak, meer spesifiek die eienskappe van verlenging (elongation) en elliptisiteit, tussen die twee lyne waargeneem. In toekomstige studies moet die morfometriese eienskappe van skaapsperme verder bestudeer word, asook die korrelasie daarvan met die bevrugtingsvermoë na ontdooiing bepaal om sodoende die diepbevriesing protokolle van skaapsperme te optimaliseer.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Reproduction and robustness traits are integral in ensuring sustainable, efficient and profitable sheep farming. Increases in genetic gain of reproduction and robustness traits are however, hampered by low heritability coupled with the difficulty in quantification of these traits for traditional selective breeding strategies. The aim of the current study was therefore to identify genomic regions underlying variation in reproduction traits and elucidate quantitative trait loci (QTL) and/or genes associated with reproductive traits. The Elsenburg Merino flock has been divergently selected for the ability to raise multiple offspring and has resulted in a High and a Low line that differ markedly with regard to reproductive output and other robustness traits. The flock thus served as an ideal platform to identify genomic regions subject to selection for reproductive traits. To pinpoint genomic regions subject to selection, a whole-genome genotyping platform, the OvineSNP50 chip, was selected to determine the genotype of more than 50 000 SNPs spread evenly across the ovine genome. The utility of the OvineSNP50 chip was determined for the Elsenburg Merino flock as well as additional South African Merino samples and three other important South African sheep breeds, the Blackheaded Dorper, South African Mutton Merino (SAMM) and the Namaqua Afrikaner. Although genotyping analysis of the Elsenburg Merino flock indicated some signs of poor genotype quality, the overall utility of the genotype data were successfully demonstrated for the South African Merino and the other two commercial breeds, the Dorper and SAMM. Genotyping results of the Namaqua Afrikaner and possibly other indigenous African breeds may be influenced by SNP ascertainment bias due to the limited number of indigenous African breeds used during SNP discovery. Analysis of pedigree, phenotypic records and SNP genotype data of the Elsenburg Merino cohort used in the current study, confirmed that the lines are phenotypically as well as genetically distinct. Numerous putative genomic regions subject to selection were identified by either an FST outlier approach or a genomic scan for regions of homozygosity (ROH) in the High and Low lines. Although annotated genes with putative roles in reproduction were identified, the exact mechanism of involvement with variation in reproduction traits could not be determined for all regions and genes. Putative ROH overlapped with QTL for several reproduction, milk, production and parasite resistance traits, and sheds some light on the possible function of these regions. The overlap between QTL for production and parasite resistance with putative ROH may indicate that several, seemingly unrelated traits add to the net-reproduction and may have been indirectly selected in the Elsenburg Merino flock. A SNP genotyping panel based solely on reproduction traits may therefore be ineffective to capture the variation in all traits influencing reproduction and robustness traits. A holistic selection strategy taking several important traits, such as robustness, reproduction and production into account may as such be a more effective strategy to breed animals with the ability to produce and reproduce more efficiently and thereby ensure profitable and sustainable sheep farming in South Africa. / AFRIKAANSE OPSOMMING: Reproduksie- en gehardheids-eienskappe is noodsaaklik om volhoubare, doeltreffende en winsgewende skaapboerdery te verseker. ‘n Toename in genetiese vordering in reproduksie- en gehardheids-eienskappe word egter bemoeilik deur lae oorerflikhede tesame met die probleme in kwantifisering van hierdie eienskappe vir tradisionele selektiewe diereteelt strategieë. Die doel van die huidige studie was dus om gebiede in die genoom onderliggend tot variasie in reproduksie-eienskappe te identifiseer en die rol van verwante kwantitatiewe eienskap loki (KEL) en/of gene met reproduktiewe eienskappe te bepaal. Die Elsenburg Merinokudde is uiteenlopend geselekteer vir die vermoë om meerlinge groot te maak en het gelei tot 'n Hoë en 'n Lae lyn wat merkbaar verskil ten opsigte van reproduksie-uitsette en ander gehardheids-eienskappe. Die kudde het dus gedien as 'n ideale platform om genomiese areas onderhewig aan seleksie vir reproduksie-eienskappe te identifiseer. Om vas te stel waar genomiese areas onderhewig aan seleksie gevind kan word, is ‘n heel-genoom genotiperingsplatform, die OvineSNP50 skyfie, gekies om die genotipes van meer as 50 000 enkel nukleotied polimorfismes (ENPs) eweredig versprei oor die skaap genoom, te bepaal. Die nut van die OvineSNP50 skyfie is bepaal vir die Elsenburg Merinokudde sowel as addisionele Suid-Afrikaanse Merinos en drie ander belangrike Suid-Afrikaanse skaaprasse, die Swartkop Dorper, Suid-Afrikaanse Vleismerino (SAVM) en die Namakwa Afrikaner. Hoewel genotipe resultate van die Elsenburg Merino kudde sommige tekens van swak genotipe gehalte getoon het, kon die algehele nut van die genotipering resultate vir die Suid-Afrikaanse Merino en die ander twee kommersiële rasse, die Dorper en SAVM, bevestig word. Genotipering resultate van die Namakwa Afrikaner en moontlik ook ander inheemse Afrika rasse kan deur ENP vasstellingspartydigheid beïnvloed word as gevolg van die beperkte aantal inheemse Afrika rasse gebruik tydens ENP ontdekking. Ontleding van stamboom inligting, fenotipe rekords en ENP genotipe data van die Elsenburg Merino-kohort gebruik in die huidige studie, het bevestig dat die lyne fenotipies asook geneties verskil. Talle vermeende genomiese areas onderhewig aan seleksie is geïdentifiseer deur 'n FST uitskieter benadering of deur ‘n genomiese skandering vir gebiede van homogositeit (GVH) in die Hoë en Lae lyne. Hoewel geannoteerde gene met potensiële rolle in reproduksie geïdentifiseer is, kan die presiese meganisme van betrokkenheid by variasie in reproduksie-eienskappe nie bevestig word vir al die gebiede en gene nie. Vermeende GVH oorvleuel met KEL vir 'n paar reproduksie-, melk-, produksie- en parasietweerstand-eienskappe, en werp daarom lig op die moontlike funksie van hierdie gebiede. Die oorvleueling tussen KEL vir produksie en parasietweerstand met vermeende GVH kan daarop dui dat 'n hele paar, skynbaar onverwante, eienskappe bydrae tot net-reproduksie, wat indirek geselekteer mag wees in die Elsenburg Merino-kudde. ‘n ENP genotiperingspaneel uitsluitlik gebaseer op reproduksie-eienskappe mag daarom onvoldoende wees om die variasie in alle eienskappe wat betrekking het op reproduksie- en gehardheids-eienskappe, in te sluit. ‘n Holistiese seleksie strategie wat verskeie belangrike eienskappe, soos gehardheid, reproduksie en produksie in ag neem, mag ‘n meer effektiewe strategie wees om diere te teel met die vermoë om in 'n meer doeltreffende manier te produseer en reproduseer en om daardeur winsgewende en volhoubare skaapboerdery in Suid-Afrika te verseker.

Bibliography: leaves 325-341. Skin and fleece measurements were recorded at different ages for both male and female sheep from the Turretfield Merino Resource Flock and used to estimate the heritability of each trait and the phenotypic and genetic correlations among and between the skin and fleece traits. Generally, the heritability of each trait was high, which indicates that both the fleece and skin traits should respond well to selection.

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