Different combinations of saturated and unsaturated fatty acids were fed to broilers to establish their effect on the fatty acid composition of the broiler carcass and the abdominal fat pad. Six combinations of Canola acid oil (CAO, high levels of C18:3n-3 and monounsaturated fatty acids) and Famarol acid oil (FAO, high levels of C18:2n-6 and saturated fatty acids) were included in the broiler diets from one day of age to six weeks of age, viz. 100% FAO, 80% FAO-20% CAO, 60% FAO-40% CAO, 40% FAO-60% CAO, 20% FAO-80% CAO, 100% CAO. There were no statistically significant differences between dietary groups in weight gain (1.71 ± 0.059 kg) or feed conversion ratios (1.97 ± 0.051 g feed/g gain). No significant differences between treatments were found in the moisture (66.20 ± 0.112%), protein (17.63 ± 0.484%), lipid (15.92 ± 1.507%) and ash (0.95 ± 0.115%) concentration of the carcasses, nor in the moisture (28.77 ± 0.112%), protein (3.03 ± 0.484%), lipid (63.32 ± 9.789%) and ash (0.45 ± 0.135%) concentrations of the abdominal fat pads. With the increase in dietary CAO levels, the mean percentages of C18:2n-6 and C20:4n-6 in the carcasses decreased respectively with 1.78% units from 20.88% and 0.35% units from 1.05%, whilst C18:3n-3 and longer chain n-3 fatty acids such as C20:5n-3 and C22:6n-3 increased respectively with 2.25% units from 1%, 0.1% units from 0.1% and 0.67% units from 0.2%. The same tendency was seen in the abdominal fat pads where C18:2n-6 and C20:4n-6 decreased respectively with 1.55% units from 20.75% and 0.98% units from 1.2% with an increase in dietary CAO, whilst C18:3n-3, C20:5n-3 and C22:6n-3 increased respectively with 2.13% units from 1.15%, 0.45% units from 0.03% and 0.95% units from 0.05%. The n-3/n-6 ratio in the carcasses and abdominal fat pads increased respectively with 0.16% units from 0.06% and 0.19% units from 0.06% with an increase in dietary CAO. These results clearly indicate that dietary CAO enriched with α-linolenic acid lowered the saturated fatty acid concentrations in broiler carcasses and abdominal fat pads with 4.88% units and 10.63% units respectively, and increased the monounsaturated fatty acid concentrations with 3.87% units and 7.25% units, respectively and polyunsaturated fatty acid concentrations with 1.02% units and 2.38% units, respectively. The results of this experiment showed that substitution of Famarol oil with Canola oil in broiler diets can increase the ratio of n-6 to n-3 fatty acids in broiler carcasses and abdominal fat pads to 5:1, a ratio more suitable for human health. Increasing the level of n-3 fatty acids in the diets was also effective in reducing the level of saturated fatty acids in the carcasses and abdominal fat pads of broiler chickens resulting in "healthier" chickens.

Experiment 1 was carried out with 220 one-day-old broiler chicks to evaluate the effect of 11 different levels of vitamin E supplementation (viz. 0 to 200 mg α-tocopheryl acetate/kg diet) on the production performance of broilers and oxidative stability of frozen broiler carcasses. The diets with vitamin E levels of 0 to 100 mg were fed from day-old to 42 days of age, and the diets with vitamin E levels of 120 to 200 mg were fed from 21 to 42 days of age. The oxidative stability, evaluated by thiobarbituric acid reactive substances (TBARS), was determined after 30, 90, 120 and 150 days of storage at -20 °C. There were no differences in weight gain (2.29 ± 0.397 kg) or feed conversion ratios (1.85 ± 0.111 kg feed/kg gain) between dietary treatments. TBARS values increased with increasing time of storage (basal diet: day 30 = 1.71 ± 0.51; day 150 = 4.89 ± 0.51), but decreased with increasing vitamin E levels (day 150: basal = 4.89 ± 0.51; 100 mg/kg = 1.09 ± 0.27). Experiment 2 was carried out with day-old broiler chicks to evaluate the effect of five levels of vitamin E supplementation (viz. 0 to 160 mg α-tocopheryl acetate/kg diet) on performance parameters and the oxidative stability of refrigerated carcasses. The experimental diets were fed from dayold to 42 days of age. Oxidative stability, evaluated by TBARS, colour deterioration and microbiological stability was determined after 0, 4, 8, 10 and 12 days of storage at 4 °C. Fatty acid analysis was done on samples obtained on days 0 and 12. There were no differences in total weight gain (2.37 ± 0.467 kg) or feed conversion ratio (1.88 ± 0.117 kg feed/kg gain) between dietary treatments. TBARS values increased with increasing storage time, but decreased with increasing vitamin E levels. There were no differences between treatments for colour measurements for L* (44.97 ± 0.662), a* (5.23 ± 0.315) or b* (12.76 ± 0.321) values. Microbiological counts increased over time, but dietary vitamin E concentration had no effect. There were no differences between dietary treatments for any of the groups of fatty acids measured (SFA: Day 0 = 26.1 ± 1.13 %, Day 12 = 26.1 ± 1.17 %; MUFA: Day 0 = 41.4 ± 1.46 %, Day 12 = 40.2 ± 2.28 %; PUFA: Day 0 = 32.4 ± 1.95 %, Day 12 = 33.8 ± 2.52 %). Similarly, fatty acid proportions did not change over time. There were no differences between dietary groups for mean muscle pH (6.01 ± 0.206).

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