|Keywords (Extracted from title, table of contents and abstract of thesis)
fatty acid, ruminents milk, meat, dairy products,livestock, sindh, saturated fatty acids, cholesterol, monounsaturated fatty acids, polyunsaturated fatty acids, omega-3, eicisopentanoic acids, docosahexaenoic acid, conjugated linolenic acids, butyric acid, milk lipids, buffaloes, cows, ewes, goats
Fatty acids being essential components of human diet play an important role in our metabolism and growth. They are classified as essential and non-essential based upon their properties. There is a considerable evidence to suggest that saturated fatty acids (SFA) increases serum cholesterol level in humans and thus contributes to various heart diseases. However, monounsaturated fatty acids (MUFA) and polyunsaturated Fatty acids (PUFA) including essential fatty acids such as Omega-3s have beneficial effect in reducing cholesterol. Considerable progress has been made in enriching the omega-3 PUFA content of animal foodstuffs, particularly Eicisopentanoic acids (BP A; C 20:5) and docosahexaenoic acid (DHA, C 22:6) which are of great importance due to their beneficial effects on humans. Like wise conjugated linolenic acids (CLA) and butyric acids originated from ruminant (buffalo, cow, goat, sheep) metabolism are also of major interest due to their anti- carcinogenic and anti- diabetic's properties in human and several animal models.
Pakistan is the 5th largest producer of milk in the world and dairy by far is the largest livestock sector contributing 13.4 % of country total GDP during the year 2004-05. Considerable efforts are being made to enhance the milk production due to increasing population in the country; however the nutritional side has been neglected. Therefore, the present work was undertaken to evaluate the nutritional quality of milk fat from ruminants (buffalo, cow, goat and sheep), their meat and dairy products in selected areas of Sindh province. These ruminants are raised under traditional feeding system.
This is an overall three year study divided into five parts. In the first part of the study the fatty acid composition particularly level of conjugated linoleic acid (CLA) content in ruminants milk (Buffalo, cow, goat and sheep) from Sindh, (pakistan) with varying season was investigated. Milk samples (n= 404) were collected throughout the year (July 2003 -June 2004) during four periods i.e. winter (December to February), spring (March-April), summer (May-September) and autumn (October-November) seasons. The result of that part of study shows that summer milk produces better profile with less saturated fatty acids, more unsaturated and CLA proportions in all ruminant milk investigated compared to rest of the year. It appears that naturally grown fresh grass during summer (monsoon) affects the biohydrogenation pathways. Due to changes in the rumen population, altered pH or unidentified factors in grass that inhibit biohydrogenation and increases CLA and trans-C 18:1 fatty acids content (biohydrogenation intermediates).
In the Second part of the study difference among indigenous breeds of cows (Red Sindhi, White Thari), water buffaloes (Kundi, Nili Ravi), goats (Kamori, Pateri) and ewes (Kooka, Kacihi) for fatty acid composition were investigated. Results of that of the study showed that breed impacted significant difference in milk fatty acid composition of ruminants received same diet and housed under the same conditions, comparable to previous reported data. The variability among breeds might be useful in the quality improvement of milk and derived products. Also, implementation of feeding strategies for ruminates; in order to improve milk fat nutritional value and consumer's acceptation should be considered
In third phase analysis of dairy products (n =140) including yogurt (n= 35), cheese (n = 42), butter (n= 49) and cream (n =14), were carried out for their fatty acid potential. The study reveals that among dairy products no significant differences were observed for fatty acids profile, however the results for beneficial fatty acids especially CLA and essential fatty acids for dairy products were lower than literature values. This is attributed to the fact that buffalo milk (low in beneficial fatty acids and high in cholesterol raising fatty acids) is used in most of the dairy products in Pakistan which is in contrast to Europe and America where cow / sheep milk is used for making these products.
In the fourth part meat sample of Kundi steers (n=15) and goat (n=25) was analyzed for intramuscular fatty acid profile. The samples were taken from longissimus dorsi region (loin portion, and ribeyeportion) and distal region of semitendinosus muscle. Intramuscular fat from Kundi steers and Kamori goats reared under the typical production system of Pakistan did not show significant differences in fatty acid composition of three localized muscles investigated in the present work.
In fifth and last part of the study a simple, economical, producible and cost effective method for the fatty acid methyl ester (FAME) preparation was proposed using anion-exchange resin. The use of anion exchange resin Amberlite lRA-904 offers the FAMEs preparation method which is rapid, avoids solvent extraction and classical sponification procedure. A Plackett-Burman factorial experimental design was used as a multivariate strategy for the evaluation of the effects of varying several variables at once. A standard IUPAC method was used to prepare FAMEs from vegetable oil / fats for comparative purpose. Analytical results for the FAMEs by resin based