Correlation between blood glucose level and liver glycogen storage in Japanese Quail (Coturnix coturnix japonica)
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Date
1997
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Department of Physiology and Biochemistry, College of Veterinary and Animal Sciences, Mannuthy
Abstract
Literature available on the physiology of Japanese quail is scanty. It is only in the recent years that any concentrated attempt has been made to study the various aspects of metabolism in domestic fowl. The present study was undertaken to probe into some fundamental areas of carbohydrate metabolism in Japanese quail with special reference to the normal blood glucose level and liver glycogen content of both sexes at various ages and physiological conditions.
The study was carried out in four hundred and forty Japanese quails (both sexes) of the same strain (egg type) procured from Kerala Agricultural University Poultry Farm, Mannuthy. In the first phase of study the estimations were conducted in 40, zero day old (on the day of hatch) Japanese quail chicks. In the second phase, 400, two week old quail chicks were utilized. The males and females were separated at four weeks of age and grouped into G1 (males) and G2 (females) comprising of 20 birds in each subgroup. The birds were maintained on standard quail rations in separate compartments of the cage. Feed consumption was recorded at fortnightly intervals. Twenty birds each from G1 (males) and G2 (females) groups were sacrificed at fortnightly intervals from the second to 16th week of age for the estimations. At the sixth week of age two sets of males from G1 group (20+20) and females from G2 group (20+20) were maintained on 50 per cent feed restriction for a period of four weeks. At eighth (two weeks feed restriction) and tenth (four weeks feed restriction) week of age twenty birds each from control and 50 per cent feed restricted birds of G1 and G2 groups were sacrificed for the different estimations as blood glucose concentration, liver glycogen content, liver weight and body weight.
The results from the study revealed that the highest level of blood glucose was recorded at an age of zero day in Japanese quail (244.425 ± 2.204) mg/dl). A decreasing tendency in blood glucose level was observed as age advanced, may be due to an increase in the erythrocyte count of adult birds. In general female quails exhibited higher blood glucose level than the male quails. The highest content of liver glycogen (2.039 ± 0.102%) was recorded in the zero day. old quail chicks (on the day of hatch). The level of glycogen showed a decreasing tendency as age advanced, may be due to the utilisation of liver glycogen for the energy requirements of growing birds. There was no significant variation in liver glycogen level due to sex. However there was higher liver glycogen content in male quails at the age of two weeks.
Liver weight and body weight showed a tendency of steady increase from the day of hatch to sixteenth week of age in both sexes. The females had higher liver weight as well as body weight than the males. The increase in liver weight may be due to the increase in the number and size of liver cells and also by excess deposits of energy required for growth. The maximum body weight recorded at the age of 16 weeks in both males and females were 170.500 ± 2.244 g and 184.000 ± 4.542 g respectively. Female quails had a higher body weight than the male quails especially from sixth week of age onwards, when they attained sexual maturity. Two weeks feed restriction, did not influence the blood glucose concentration and liver glycogen content in both sexes of quails, whereas a significant reduction was noticed in the liver weight and body weight of both male and female quails. Four weeks feed restriction in male quails resulted in a reduction in blood glucose level, liver glycogen content, liver weight as well as body weight. However, in female quails the blood glucose level and liver glycogen content were not significantly altered, whereas body weight and liver weight showed a significant reduction. The female quails were able to withstand the situation by lowering the rate of egg production.
Blood glucose concentration and liver glycogen content exhibited a positive correlation in control as well as feed restricted (Two weeks and four weeks) birds. However, there was variation at different age levels in both male and female quails. The mean liver weight and liver glycogen content in both sexes of quails exhibited a negative correlation. However, there was variation in the correlation due to sex and age. Body weight and liver weight were found to be positively correlated in both sexes of quails at all age periods and even in feed restricted periods.
It was also observed that the daily feed consumption in both male and female quails increased with the advancement of age and female quails consumed more than the male quails. Over and above the information obtained from the present study on certain aspects of avian carbohydrate metabolism, further studies are required to investigate the factors influencing the regulation of normal levels of blood glucose and liver glycogen in birds. The indefinite relation at different age periods observed in Japanese quails between blood glucose concentration and liver glycogen content and the ability to withstand the changes in the levels of blood glucose and liver glycogen, due to feed restriction, attract further investigations. The factors involved may be either the predominance of alpha cells in avian pancreas or role of kidney in gluconeogenesis. It will also be interesting to investigate the compensatory mechanisms that operate at the time of feed restriction in the regulation of normal blood glucose level and liver glycogen content.
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