Abstract
This study was conducted to evaluate the effect of supplementing tuna oil to diets of growing-finishing pigs (barrows and gilts) on backfat characteristics when slaughtered at different weights. Four hundred and eighty crossbred (Large White×Landrace× Duroc) pigs averaging 30 kg were allotted to 12 treatment combinations (40 pigs/treatment combination) in a completely randomized design with a 2×2×3 factorial arrangement of treatments. The treatments were: dietary tuna oil supplementation (0 and 2%); sex (barrows and gilts); and slaughter weight (90, 100 and 110 kg). As pigs reached their slaughter weight, they were randomly selected (8 pigs/treatment combination; 96 pigs in total) and slaughtered. Backfat colour, hardness and fatty acid profile were assessed. There was significant (p<0.05) differences in colour (L* and a* values) among treatments. Backfat of control group was harder than those on the tuna oil (p<0.001) and also that of barrows was harder than of gilts (p<0.05). In addition, the thiobarbituric acid reactive substances (TBARS) values of fat from tuna oil group stored for 3 days was higher (p<0.001) than that of the control group. The TBARS values of gilts tended to be higher than that of barrows and it increased with increasing slaughter weight in the tuna oil group. The cholesterol and triglyceride levels were not affected by diet and sex but the triglyceride level increased with increasing slaughter weight (p<0.01). The tuna oil group had higher polyunsaturated fatty acid (PUFA) content, ratio of PUFA: saturated fatty acid (SFA) and total n-3 fatty acids but lower monounsaturated fatty acids content and n-6:n-3 fatty acids than those of the control group (p<0.01). Gilts had higher PUFA and n-6 fatty acids in backfat than barrows (p<0.05). The backfat from both 90 and 100 kg slaughter weight groups had a lower ratio of n6:n3 fatty acid than that of the 110 kg slaughter weight group (p<0.05). However this was more pronounced in tuna oil group. The PUFA: SFA was also increased while the n-6:n-3 ratio tended to reach the recommended levels for healthy eating in human beings of <5. However, due to oxidative susceptibility, barrows should not be slaughtered at more than 100 kg for the meat to be acceptable to
Highlights
Worldwide, people are concerned of the danger of developing atherosclerosis and coronary heart diseases when consuming food of animal origin
The most notable increases were in the proportions of C20:4n-6, C20:5n-3 and C22:6n-3 and a decrease in the proportion of C18:2n-6 when tuna oil was included in the diet
The main objective of the present study was to establish whether feeding long-chain n-3 fatty acids from tuna oil to barrows and gilts slaughtered at different weights would result in changes in backfat characteristics and composition
Summary
People are concerned of the danger of developing atherosclerosis and coronary heart diseases when consuming food of animal origin. Significant research studies have been conducted with the objective of increasing the omega fatty acid in foods of animal origin so as to minimise the risk of heart diseases (Harris, 1997; Holub, 2002). Marine fish oils are rich in omega-3 fatty acids These are presumed to reduce the risk of coronary heart diseases and atherosclerosis (Harris, 1997; Simopoulos; 2001; Holup, 2002; Morel et al, 2006). Earlier work by Jaturasitha et al (2002) demonstrated the feasibility of enriching pork and pork products with omega fatty acids by feeding tuna oil to pigs.
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