Improvement of subcutaneous fat quality of pigs by means of dietary manipulation

English: The objectives of this study were to identify feed ingredients with the potential to improve fat quality of pigs and to illustrate experimentally that it is possible to produce baconer pigs in the P and 0 classification groups with good fat quality. A questionnaire was sent to animal feed companies in South Africa to identify individual feed ingredients available as well as typical inclusion levels of such ingredients. All available lipid containing feed ingredients were then analyzed for iodine value and fatty acid composition. From this data, individual feedstuffs with the potential of improving fat quality was identified. A diet was formulated with the aim of improving fat quality of pigs cost effectively. A feeding trial was performed, comparing a control diet with the one optimized for fat quality. Fourteen Large White x Duroc gilts weighing on average ± 43 kg were randomly divided into two groups of seven pigs each and assigned to either the control or experimental diet. Pigs were provided with ad libitum access to feed and water. Feed intake was measured daily and weight was recorded every week. At ± 95 kg . live weight the pigs were slaughtered. Firmness of the subcutaneous fat was measured and colour of the backfat was determined. Lipid quality characteristics were determined on control and experimental pigs and compared with international guidelines for good fat quality. Differences in parameters between treatments were statistically compared. 102 The first objective of this experiment, namely the formulation of an experimental diet with the potential to improve the backfat quality of pigs, was successfully achieved. The experimental diet had a more saturated fatty acid profile than the control diet as indicated by iodine value and fatty acid analysis. No significant differences (P > O.O~) were observed in growth performance and carcass characteristics between the control and experimental groups. All pig carcasses were classified as either P or 0 carcasses. Minolta colour measurements (L*, a*, and b* values) of the backfat did not differ significantly (P > 0.05) between the control and experimental group. The fat hardness measurement of the experimental group was significantly higher (P < 0.01) than that of the contro 1 group, indicating that backfat from the experimental group was firmer than that of the control group. The same significant (P < 0.001) trend was observed in refraction index value with refraction index of backfat from the experimental group lower than the internationally proposed maximum of 1.4598 while the control group had a value higher than 1.4598. A significant difference (P < 0.001) was also observed in backfat iodine value with the experimental group having an iodine value lower than the internationally proposed maximum of 70 and the control group having a value higher than this maximum. Anatomical differences was found in subcutaneous fat saturation. Backfat had higher iodine values (more unsaturated) than subcutaneous fat in the belly area (more saturated). As far as the fatty acid composition were concerned, the experimental group had a significantly higher (P< 0.001) content of saturated fatty acids (C16:0 and C18:0) than the control group. Linoleic acid content of subcutaneous fat from the experimental group was lower than the internationally proposed maximum of 15 % while C18:2 content of the control group was higher than this maximum. These fatty acid differences were also reflected in the fatty acid ratios and resulted in the experimental group conforming to most international guidelines for fat quality. The experimental group conformed to the following international guidelines for fatty acid ratios while the control group did not: total trienoic fatty acids, total penta- + hexaenoic fatty acids, total UFA, total PUFA, C18:0/C18:2 ratio and double bond index.