Influence of chitin on growth and fatty acid composition in growing pigs

Abstract

A study was carried out to find out the influence of feeding chitin to pigs on their growth, carcass characteristics, blood cell count and haemoglobin concentration, serum cholesterol and triglyceride levels, and fatty acid profile of muscle and backfat. Twenty-four weaned female piglings of Large White Yorkshire breed were assigned to three groups of eight each. Two groups were fed chitin with a standard farm ration at levels of 0.5 per cent (Group I) and I per cent (Group 2), and the remaining group, which served as the control, was fed only the ration without addition of chitin (Group 3). All animals were housed individually and were fed in two I-hour feeding periods daily. Digestibility of chitin did not differ between the two chitin-fed groups. The percentage of digestibility increased from age 3 months (79.37 ± 1.85 to 80.49 ± 1.85) to 5 months (95.36 ± 1.13 to 96.54 ± 1.05) and thereafter remained constant at 7 months (95.35 ± 1.33 to 95.77 ± 1.57). The chitin-fed groups had significantly (P<0.05 or 0.01) higher body weights than the controls from 18th to 40th week of age. Compared with the controls, the chitin-fed groups had higher total gains in weight by 11 to 12 kg. Both the chitin-fed groups also had significantly (p<0.05 or 0.01) higher average daily gains than the controls from 18th to 40th week of age. The pigs in all groups showed a peak rate of gain at 32nd week of age. The chitin-fed groups also averaged higher body lengths, heights and girths, and also higher daily gains in these measures as compared with the control group. Daily feed intake increased with age of animals in all the groups. Daily feed intake did not differ significantly between the groups. For all the groups, maximum feed efficiency was recorded between 16th and 30th week of age. As compared with the controls, the chitin-fed groups showed higher feed efficiency. The difference between the control and chitin-fed groups were found to be significant (P<0.05) at the end of the experiment. The pigs in the chitin-fed groups averaged higher slaughter weights than the controls at 5, 7 and 9 months of age. For all the pigs in all groups, carcass length, ham weight and eye-muscle area showed higher percentages of gain between 5 and 7 months than between 7 and 9 months of age. The percentage of ham decreased with increase in age and weight of animals. The chitin-fed groups of pigs showed higher carcass lengths, ham weights and eye-muscle areas than the control group at each stage of slaughter. The backfat deposition showed a higher deposition between 5 and 7 months than between 7 and 9 months of age, while the majority of leaf fat deposition took place between 7 and 9 months of age. The percentage of leaf fat increased with increase in age and weight of animals in all the groups. The chitin-fed groups showed lower backfat thickness and lower percentages of leaf fat than the controls at each stage of slaughter. The increase in dressing percentage was found to be higher between 7 and 9 months than between 5 and 7 months of age, for all groups of pigs. The chitin-fed groups yielded higher dressing percentages than the control group at each stage of slaughter. The weight of internal organs increased with age of animals, whereas weight of internal organs as percentage of live weight decreased. The control group of pigs had higher percentages of internal organs than the chitin-fed groups at each slaughter age. The haemoglobin concentration, total erythrocyte count, total leukocyte count, and differential leukocyte count did not differ significantly between the groups of pigs at 5, 7 or 9 months of age. The pigs in group 2 averaged the lowest serum cholesterol and triglyceride levels followed by the pigs in group I and group 3, in that order, at 5,7 and 9 months of age. The difference in serum cholesterol concentration between the pigs in group 2 and the pigs in either group 1 or group 3 were found to be significant (p<0.05) at 7 months and highly significant (p<0.01) at 9 months of age. The serum triglyceride concentration followed the same trend as serum cholesterol concentration, between the groups of pigs. However, the differences were not found to be statistically significant. The fatty acid composition of muscle and backfat did not differ noticeably between the groups at 5 months of age. At the subsequent ages of 7 and 9 months, the chitin-fed groups showed markedly higher degree of unsaturation and lower saturation than the control group. Higher percentages of oleic acid and lower percentages of palmitic acid were recorded for the chitin-fed groups as compared with the control group. The results revealed that chitin had growth-promoting, hypolipidemic and hypocholesterolemic effect in pigs. It also improved the degree of unsaturation in pig meat.