Effect of dietary fatty acid composition of different lipid sources on the fatty acid composition of pork fat tissues : a numerical literature review : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North, New Zealand

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Based on the current database, in this dissertation attempts were made to investigate and summarize the effects of dietary Fatty Acid (FA) content of different lipid sources on the fatty acid composition of pork fat tissues. A total number of 84 related research publications were picked for the review, of which 23 articles were thoroughly studied and 17 were ultimately chosen for analysis based on defined criterion. All the 17 articles reported a strong correlation between dietary fatty acids and fatty acid in tissues of pigs, but their effect on increasing those FA in pig tissues was inconsistent and insignificant. In the 17 articles selected for analysis, a total of 52 dietary treatments were extracted which reported FA composition of which 45 diets displayed FA composition in Sub-Cutaneous adipose tissue (SC) and 35 displayed FA composition in Longissimus Muscle (LM). Nine major lipid sources were identified in the selected 52 diets out of which 7 sources reported enough components in diet to carry out regression analysis, correlation coefficients and provided information to compare them. Majority of the diets selected had a Soya bean Oil (SBO) source (10) followed by Linseed Oil (LO) (7) and Animal Tallow (AT) (7). As there are (9) Special Oils (SO) made up of blends and different oil sources, which are less prevalent, they were grouped together to symbolize them. Each lipid source proved to be the source of certain specific FA groups and they integrated those specific FA into fat tissues of pork, resulting in changes in FA composition. Animal Tallow (AT) diets resulted in the highest Saturated Fatty Acid (SFA) content in diets (42.03%) and Conjugated Linoleic Acid (CLA)- added diets resulted in the highest SFA content in fat tissues: SC (42.73%) and LM (45.35%). Both these lipid sources elicited most of SFA related changes in pigs' bodies. AT had better correlation values between the diets and SC (0.696), LM (0.613), while CLA- added diets had the highest regression intercepts for both the tissues: SC (95.27), LM (37.14) compared to other lipid sources. Sunflower Oil (SFO) was the major source for Monounsaturated Fatty Acids (MUFA). Highest MUFA mean percentage in tissues: SC (48%) and LM (51%) was observed with SFO treatments followed by SO. Both the oils had highest mean percentage of MUFA in diets (39.3 % and 40.6 %) respectively. In comparison to all other diets, the sunflower oil diet had one of the greatest increases in regression equation intercept (30.1%) for SC, and the highest increase (46.89%) for LM. Like SFA, the highest correlation between MUFA diet and SC is found in SFO diet (0.984) followed by SO diet (0.949). Similarly, greatest correlation between diet and LM is observed in the same diets (0.613), (0.370) respectively. SO diets and AT diets displayed higher MUFA SC percentage compared to LM percentage, whereas all other diets contradicted this, with higher MUFA percentage being observed in muscles but not fat tissue. SBO, LO and Fish Oil (FO) were the best providers of Poly Unsaturated Fatty Acids (PUFA) among the lipid sources identified. FO diets had one of the highest PUFA mean percentage (46.4%), less than diets like SFO (46.8%), SBO diet (54.72 %) and LO diet (56.01%). FO had slightly higher PUFA mean SC than SFO (20.38 % and 19.25 %). Though having lesser mean PUFA diet content compared to SBO and LO, FO had greatest increase in regression intercept (20.11%) for PUFA SC indicating its effective dominance in incorporating more PUFA into SC than any other diets. Highest individual PUFA content in diet is prominent in SBO diets (70.9%) indicating it as one of the best sources for PUFA. SBO also had the second highest mean PUFA in diets (54.72%) next to LO diet (56.1%). A similar trend is followed in the regression intercept of PUFA LM and PUFA SC with these diets. Though having lesser PUFA diet percentage, SBO displayed greatest mean percentage of PUFA SC and PUFA LM (27.41 and 20.99). LO diet had the highest mean percentage PUFA diet (56.01) among all the dietary treatments. Despite having highest PUFA percentage diet, LO had lesser mean percentage of PUFA SC (24.75) and PUFA LM (14.24) compared to SBO (27.41 and 20.99) respectively. LO had greater increases in regression intercept of the tissues with diets compared to SBO. SFA and MUFA can be synthesized in the bodies of pigs but not PUFA, thus they are known as essential FA, and they should be supplied to the animals through diet alone. Though having greater PUFA mean percentage in diet and tissues, SBO and LO didn’t increase n-3 PUFA such as Eicosapentaenoic Acid (EPA), Docosahexaenoic Acid (DHA) and Docosapentaenoic Acid (DPA) which are only found in FO, and which are also important in terms of human health. Keeping n-3 PUFA aside, it is evident from the review that plant-based lipid sources like SBO and LO can increase overall PUFA content better than FO and they are economical to use at farm level. Moreover, with increased commercial fishing we are causing irreparable damage to the oceans and ecology, which must be mitigated, and more agricultural practices must be pursued to reduce our carbon footprint. Therefore, using plant-based lipid sources as an alternate to FO is advised and future research should focus on developing better n-3 PUFA sources to lessen our reliance on fisheries to obtain these FA.