Thesis (MSc Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The aim of this study was to determine the proximate composition of five individual body sites of the Mustelus mustelus shark in order to evaluate the cross carcass variation of the individual proximate components (moisture, protein, lipid, ash) of the meat. This variation was determined in order to find a representative sample of the edible part of the shark (fillet and body flap). Secondly, this sample representing the entire shark fillet was used to investigate the endogenous factors (gender, size and life cycle stage) and their effects on the individual proximate components and other meat components (amino acids, fatty acids, minerals, histamine and mercury contents). Finally, all this data was combined to describe the average chemical composition and nutritional value of M. mustelus meat. None of the proximate components showed any variation between the different fillet positions. This indicated that the fillet is homogenous and samples for chemical analyses can be taken anywhere on the fillet as representative of the entire fillet. It was found that all three main effects (gender, size and life cycle stage) did not have major influences on most of the components of the chemical composition of M. mustelus meat analysed. Higher fatty acid levels (SFA, MUFA and PUFA) were observed in large females than in large males as well as in non-pregnant large females compared to pregnant large females. According to statistical analysis, large males had higher total mercury levels than large females. The only component affected by size variation was the fatty acids, showing a trend to decrease in quantity before maturity was reached. Variation due to life cycle stages was mostly evident in the fatty acid component with some small effects on two mineral components, aluminium and copper, which had slightly higher levels in pregnant large females than in non-pregnant large females. M. mustelus meat has an average proximate composition of 75% moisture, 23% protein, 1.6% lipids and 1.4% ash (weight per wet weight). The protein is, however, an over-estimation of the true protein value as the meat contains significant amounts of non-protein nitrogen (NPN) in the form of urea which contributes to the N concentration. M. mustelus meat is a good source of some essential amino acids, especially lysine and threonine (78% of the daily requirements for an adult in a 100g portion), but low in minerals. The meat has a healthy lipid content with a good ratio (>0.45) of PUFA:SFA (0.83) as well as a healthy (<4) n-6:n-3 fatty acid ratio of 0.39. The histamine content was very low or not detectable but some samples contained total mercury values above the maximum safe limit. Although further research is needed for some meat components, these results are a valuable contribution to the new South African Food Composition Tables being compiled. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die proksimale samestelling van die vleis vanaf vyf afsonderlike posisies op die liggaam van die Mustelus mustelus haai te bepaal. Sodoende is die variasie, met betrekking tot die verskillende proksimale komponente (vog, proteïen, lipiede en as), in terme van die totale karkas, bepaal. Die proksimale variasie is bepaal om vas te stel hoe ʼn verteenwoordigende monster van die totale karkas geneem kan word. Gevolglik is hierdie verteenwoordigende monster gebruik om die effek van geslag, grootte en die verskillende fases van die lewens-siklus op die afsonderlike proksimale komponente asook ander vleis komponente (aminosure, vetsure, minerale, histamien en kwik inhoud) te ondersoek. Laastens is al hierdie inligting gebruik om die algemene samestelling en voedingswaarde van M. mustelus vleis te bespreek. Geen van die proksimale komponente het enige variasie getoon tussen afsonderlike liggaamsposisies nie. Hierdie resultaat dui daarop dat die vleis van ʼn M. mustelus haai homogeen is regoor die karkas en dat ʼn vleis monster vanaf enige posisie op die karkas geneem kan word as ʼn verteenwoordigende monster. Daar is gevind dat geslag, grootte en fase van die lewens-siklus geen merkwaardige invloed het op die vleis se samestelling nie. Hoër vetsuur konsentrasies (versadigde, monoonversadigde en poli-onversadigde vetsure) is gevind in groot vroulike haaie en nie-dragtige vroulike haaie as in groot manlike haaie en dragtige vroulike haaie onderskeidelik. Statisties, het groot manlike haaie hoër vlakke van totale kwik as groot vroulike haaie. Die enigste vleis komponent wat beïnvloed is deur die grootte van die haai, is die vetsure, wat verminder het voor volwassenheid bereik is en dan weer vermeerder soos die haai groter word. Variasie as gevolg van die verskillende fases van die lewens-siklus is meestal gevind in die vetsuursamestelling, en die minimale het ook gevarieer ten opsigte van die elemente aluminium en boor wat effense hoër vlakke getoon het in dragtige haaie as in nie-dragtige haaie. M. mustelus vleis het ʼn gemiddelde proksimale samestelling van 75% vog, 23% proteïen, 1.6% lipiede en 1.4% as (nat massa). Die proteïen waarde is ʼn oorskatting van die ware proteïen waarde as gevolg van hoë nie-proteïen stikstof in die vorm van ureum wat bydra tot die totale stikstof inhoud. M. mustelus vleis blyk ʼn goeie bron van sommige essensiële aminosure soos lisien en treonien (78% van die daaglikse aanbevole dosis), maar laag in mineraal inhoud. Die vleis het ʼn gesonde vet inhoud met ʼn goeie (>0.045) poli-onversadigde:versadigde vetsuur verhouding (0.83) asook ʼn gesonde (<4) omega 6 tot omega 3 vetsuur verhouding van 0.39. Die histamien inhoud van die vleis was baie laag of onder die meetbare limiet, maar sekere monsters het ʼn totale kwik inhoud getoon wat bo die maksimum veilige limiet is. Hoewel verdere navorsing ten opsigte van sekere van die vleis komponente vereis word, lewer hierdie resultate ʼn waardevolle bydrae tot die nuwe Suid-Afrikaanse voedsel samestellings tabelle wat tans opgestel word.

This research project consisted of five experiments. The main objective of this study was to determine the effects of restricted feeding and season on growth, carcass characteristics, meat chemical composition, reproduction and egg laying performance of Koekoek chickens. Feed restriction lowered the body weight, weight gain, feed intake and improved the feed conversion efficiency during the rearing phase. During the laying phase, chickens that were in the RA treatment had higher body weights, weight gains and lower FCR. Chickens that were reared in summer had a higher body weight, weight gain and FCR, while total feed intake and mortality rates were high in winter. Feed restriction reduced the slaughter weight, defeathered weight, dressed weight, skin weight, breast muscle weight, shank width, chest width and heart girth during the rearing phase. The intestine, liver and abdominal fat pad weights were higher in chickens that were fed ad libitum. Chickens that were reared in summer had higher shank width, slaughter weight, defeathered weight, chest width, heart girth, breast muscle weight, skin weight, abdominal fat pad weight, intestine weight, liver weight and the relative skin percentage at the age of 18 weeks. During the laying phase, abdominal fat pad weight, abdominal fat pad percentage, intestine percentage, liver weight, gizzard weight and gizzard percentage were higher in the ad libitum fed chickens. Unrestricted feeding during the rearing phase increased the development of combs, wattles, pubic bones, ovaries and oviducts more than restricted feeding while at the age of 32 weeks, enhanced growth of the reproductive organs was seen in chickens that were fed ad libitum only during the laying phase (RA). The cold winter conditions hindered the growth of the combs, wattles, pubic bones, oviducts and ovaries. Restricted feeding during the laying phase reduced the laying percentage, egg weights and improved the hatching percentage. Ad libitum feeding during the rearing phase resulted in the attainment of puberty at an earlier age in chickens. Chickens that were produced in summer reached puberty first as well as 20%, 50% and 80% egg production, and had a higher average laying percentage and egg weights. / Thesis (PhD)--University of Pretoria, 2012. / Animal and Wildlife Sciences / unrestricted

The study evaluated the effects of genotype and grainless diets under stall-fed (n=72) conditions on the following parameters using the Afar, Central Highland goats, (CHG) and Long-eared Somali, (LES) goats. The diets varied in concentrate: roughage ratios. Diet 1 was a 50: 50 ratio (8.5 MJ ME/kg DM), Diet 2, 65:35 (9.2 MJ ME/kg DM) and Diet 3 an 80:20 ratio (10 MJ ME/kg DM), respectively. The same genotypes reared under the extensive grazing systems were also evaluated. Intake, feed efficiency (FE) and rumen parameters Total DMI ranged between 2.6 and 3.0 % on a body weight basis and between 53.5 and 62.3 g per kg metabolic body weight. The LES had a higher (P<0.001) DM roughage intake, total DMI (P<0.01) and FE (P<0.05). Goats on Diet 3 had higher (P<0.001) total DMI (g/d). Diet 1 however, displayed higher (P>0.05) FE. The mean concentration of NH3-N (39.4-53.7 mg/100ml rumen fluid) was above the N requirements for optimal microbial activity. The mean pH was similar between diets and ranged from 6.43 to 6.63. Total VFA was depressed (P<0.01) with increased grainless concentrate in the diet. Diet 1 recorded a higher (P<0.01) total VFA and lower (P<0.01) NH3-N concentration, indicating that feed nitrogen was more efficiently utilized in Diet 1. The molar proportions of acetate, propionate and butyrate varied (P>0.05) from 64.5 to 65.7, 17.7 to 18.8 and 10.7 to 12.8%, respectively. The ratio of acetic: propionic was not affected by diet (P>0.05) and ranged from 3.5 to 3.81. The values for degradation constants were similar (P>0.05) between the diets. However, the hay DM and neutral detergent fibre were more degradable (P<0.05) in goats fed Diet 1. Differences in DMI and FE between the genotypes were recorded with the LES breed being superior. Among the grainless diets, the 50:50 ratio created a favorable rumen environment and resulted in a better FE under a feedlot system. Carcass characteristics and meat quality of extensively managed goats Genotypes were similar (P>0.05) for most of carcass traits, at an average slaughter weight of 13.8 kg. The genotypes had a mean hot carcass weight of 5.9 kg and a dressing percentage (DP) on a slaughter body weight basis of 42.8%. The CHG had a 52% higher (P<0.01) chilling loss than the other genotypes. The rib physical composition was similar between genotypes, except for fat proportion. The CHG had the lowest (P<0.05) fat proportion. The chemical composition was similar between the genotypes, with the CHG having the lowest (P>0.05) chemical fat percentage. The composition of most muscle fatty acids was affected by genotype. The LES breed presented a beneficial ratio of n-6: n-3 PUFA favorable to consumers’ health. The goats under the extensive system in general, were characterized by a lower carcass weight and poor carcass fat cover. Hence, to improve the carcass characteristics it is essential that grazing goats should be supplemented or stall-fed with locally available concentrates depending on the grazing resources of the agro-ecologies and the objectives of the goat farmers. Growth and carcass characteristics of stall-fed goats The LES breed had significantly higher growth rates (ADG), heavier pre-slaughter, slaughter, empty body weight (EBW) and carcass weights than the Afar and CHG goats. Effect of diet was also significant on ADG, but similar for carcass traits, except for DP on EBW basis and some non-carcass components. The DP on an EBW basis, was the highest (P<0.01) for Diet 1. Stall-feeding of the goats improved the mean carcass weight by 38% over the initial slaughtered groups. Genotype affected the DP and it ranged from 42.5 to 44.6% and 54.3 to 55.8% on a slaughter weight and on EBW basis, respectively. The ultimate carcass pH was between 5.61 and 5.67 and chilling losses ranged from 2.5 to 3.1 %. The rib physical composition (fat and bone) differed between genotype and ranged from 72-73 %, 6.9-10.9% and 17.1-20.2% for muscle, fat and bone respectively. The findings indicate that breed differences were reflected in carcass characteristics. Meat quality of stall-fed goats Genotype significantly influenced the carcass fat and crude protein (CP) concentration, with the values ranging from 10.3 to 14.0% and 19.3 to 21.1%, respectively. The Afar and LES goats had higher fat concentration (P<0.001) compared to the CHG while the CP was higher (P<0.01; P<0.05) for the CHG. The effect of diet was significant on CP%, but was similar for fat concentration although Diet 3 tended to have a higher value. Cooking and drip loss differed (P<0.01, P<0.05) between genotypes and both traits increased with increased fatness. The effect of diet however, was similar for cooking and drip loss. Genotype and diet significantly influenced the composition of most muscle fatty acids. An interaction between genotype and diet was also exhibited on certain fatty acids. Compared to CHG, Afar and LES breeds had a higher PUFA, MUFA and UFA: SFA ratio, which are considered healthier for human consumption due to their lowering effect of cholesterol content. The relatively higher carcass fat, which is useful in reducing chilling loss and improves eating quality, the absence of C12:0 and lower concentration of C14:0, hypercholesterolemic, and higher C18:1, hypocholesterolemic fatty acids, are some of the important traits observed in Ethiopian goats. These findings suggest that a potential exists in the use of Ethiopian goat breeds fed a grainless diet, for the production of meat with specific quality characteristics. / Thesis (PhD (Animal Science))--University of Pretoria, 2008. / Animal and Wildlife Sciences / unrestricted