Effect of feeding onion (allium cepa var aggregatum g. don) and garlic (allium sativum linn) on lipid profile in Japanese quail (coturnix coturnix japonica)

Abstract

Poultry products are comparatively rich in cholesterol. WHO report indicates incidence of coronary heart disease and high dietary cholesterol level to be positively correlated. In such a situation, decreasing the cholesterol content in poultry products would be appropriate. Onion and garlic are ascribed with therapeutic effects such as hypocholesterolemia, hypolipidemia and immunosuppressant action in mammals, while no convincing reports are available on the effect of supplementation of these agents in reducing cholesterol level in egg and poultry meat. Hence, this study reports on the hypolipidemic effects and/or other effects of dietary onion and garlic on the lipid profile in the tissues of Japanese quails. Further, information on the physiological norms of tissues is essential for understanding any pathological entity. Although in recent years, the Japanese quail has gained increasing popularity as a biological model for various investigations, published reports on the lipid profile in the tissues of this species are very few. Essentially, all the previous studies on this aspect are based on observations in only a particular tissue or a particular lipid component or sex and age. Hence, the present investigation is also aimed at establishing a more or less complete picture of lipid profile in liver, plasma and muscle in both sexes at three different physiological stages of growth viz., three-week old (immature), six-week old (onset of sexual maturity) and in nine-week old (mature) birds. Likewise, the lipid profile that are analysed in the liver will also be: established in the egg yolk. The results revealed an increase in the liver and plasma total lipid content (Table II) due to onion and garlic. Although a trend of decrease in the cholesterol level in the liver and muscle was observed the results were statistically nonsignificant (Table III), indicating the hypocholesterolemic effect of onion and garlic to be of questionable biological significance.

The plasma free cholesterol level (Table IV) was found to be decreased due to onion and garlic, while no effect of the same was observed with regard to plasma esterified cholesterol (Table IV). The effect of onion and garlic on the cholesterol content in different lipoproteins (Table IV) indicated that these alliums are causing recirculation of plasma cholesterol between different lipoproteins and/or tissues in such a way that the plasma LDL-C is not increased. There was an increase in the triglyceride content in the liver and plasma due to dietary alliums (Table V). The phospholipid level in the plasma was found to be increased with a decrease in the plasma free fatty acid (Table XII) level due to dietary alliums. The variations in the plasma esterified fatty acid content (Table XII) due to alliums are in accordance with the variations in the plasma content of esterified form of lipids. The iodine value of liver lipid was increased due to alliums in both sexes, while these alliums were found to have no influence on the saponification and acid value of the liver lipid. In all the above instances where onion and garlic were found to have significant effect, dietary garlic was found to have either a similar or significantly more alliaceous effect than dietary onion. No significant variations in the lipid profile of the muscle and yolk were observed due to dietary supplementation of onion and garlic. The influence of onion and garlic on the feed consumption by birds was found to vary with duration of feeding. In the first week of feeding alliums to both sexes and in the second week in the male birds, no change in the feed consumption was observed. Thereafter in both the sexes the feed consumption increased due to dietary onion and garlic. Dietary onion and garlic caused a nonsignificant increase in the body weight. Feed efficiency in both the sexes and egg production in the females were unaltered due to dietary supplementation of onion and garlic.

The levels of total lipid, total cholesterol, triglycerides, total phospholipid and phospholipid fractions in liver, plasma and muscle were found to differ significantly due to effect of age within a sex and due to effect of sex within an age group. Similarly the level of plasma free cholesterol, esterified cholesterol, HDL-C, VLDL-C, HDL-C, free fatty acid and esterified fatty acid differed significantly due to age within a sex and due to sex within an age group. Iodine value and saponification value of lipid in liver were influenced due to age and sex, while the same was not observed in the muscle. The acid value of the lipid in the liver and muscle was unaltered due to age or sex. The feed consumption and body weight increased with age in both sexes and it was more in the females. The feed efficiency was unaltered due to age or sex. The egg production was also not influenced by age.