• M N Kutty

      Articles written in Proceedings – Animal Sciences

    • Excretion of lactic acid in exercised fishTilapia mossambica

      N V Karuppannan M N Kutty

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      Lactic acid excreted by the fish,Tilapia mossambica subjected to exercise has been measured in ambient water. The method of Barker and Summerson has been modified suitably for estimating lactic acid in the fish medium: decarbonated tap water.T. mossambica excreted 25·7, 31·1 and 31·6 mg/kg/hr of lactate at 35 cm/sec of swimming speed and 47·0, 60·2 and 54·6 mg/kg/hr of lactate at 93 cm/sec of swimming speed at the end of 1 hr of exercise at 25, 30 and 35°C respectively.

    • Oxygen consumption and nitrogen excretion in mullet,Rhinomugil corsula (Hamilton), with special reference to swimming speed

      N Sukumaran M N Kutty

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      An attempt is made to study the oxygen consumption, CO2 output and the nitrogen excretion of the freshwater mulletRhinomugil corsula. It is found that whereas the O2 consumption, the CO2 output and the respiratory quotient decreased with increase in the duration of exercise, the NH3-N and total-N excretion showed the opposite trend.

    • Influence of ambient oxygen on random activity in some freshwater teleosts

      M Peer Mohamed M N Kutty

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      The influence of ambient oxygen concentrations on random (spontaneous) activity was tested in four freshwater teleosts (mullet,Rhinomugil corsula, cichlid,Tilapia mossambica, minor carp,Puntius sarana and goldfish,Carassius auratus) at various ambient oxygen concentrations below air saturation at two temperatures 30 and 35° C. A modification of Fry’s respirometer and fish activity counter was used for the experiments. The initial ambient oxygen gradually fell from air saturation to reach the asphyxial level (the concentration at which the fish begin to lose equilibrium) by the depletion of oxygen due to the respiration of the fish itself. Among the four species tested, only inTilapia mossambica the random activity decreased with decrease in ambient oxygen whereas the other three species indicated a reverse trend. The differences in responses of random activity to ambient oxygen may be due to a dichotomy in behavioural evolution and may have a major role in the survival of the species.

    • pH regulation during long-term swimming in the mullet,Rhinomugil corsula (Hamilton)

      N Sukumaran M N Kutty

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      The regulation of blood pH during long-term swimming in mullet,Rhinomugil corsula (Hamilton) acclimated to 30° C and forced to swim in a tunnel type apparatus for five hours continuoustly was studied. The accumulation of lactic acid in muscle caused a reduction of muscle pH. But in blood the reduction of pH during the 1st hour of exercise was followed by the recovery of pH to norma level during the later hours of exercise. The maintenance of pH was apparently caused by the retention of CO2 in the form of HCO3 ions in blood.

    • Influence of hypoxia on metabolism and activity inPuntius sarana (Hamilton) (Pisces: Cyprinidae)

      M Peer Mohamed M N Kutty

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      InPuntius sarana, changes in metabolic rates in relation to ambient oxygen fell into the general pattern at 30 and 55° C, the differences being mainly in the levels of metabolism, both aerobic and anaerobic. The mean RQs at high ambient oxygen were 0.77 and 0.63 revealing that the fish were aerobic under adequate ambient oxygen. The hypoxic RQ were 1.42 and 1.90 suggesting that the fish derived considerable energy anaerobically. The aerobic AQs ranged between 0.06 and 0.18 depending on the utilization of protein and the hypoxic AQs were in consonance with the corresponding changes in hypoxic RQs. As judged from the asphyxiai oxygen level,P. sarana can live, below air saturation, up to 0.41 and 0.49 mg O2/1 at 30° and 35°C respectively. The random activity of the fish increased with decrease of ambient oxygen.

    • Influence of ambient oxygen and random swimming activity on metabolic rates and quotients in the freshwater mulletRhinomugil corsula (Hamilton)

      M Peer Mohamed M N Kutty

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      Oxygen consumption and carbon dioxide production increased with increase in random (spontaneous) swimming activity in mullet,Rhinomugil corsula in high oxygen (normoxia), but the oxygen consumption in low oxygen (hypoxia) was negatively correlated with swimming activity in tests at both 30 and 35°C. The RQ of mullet under hypoxia always remained over unity and increased with increase in activity, clearly indicating intense utilization of anaerobic energy. The RQ under normoxia remained near unity irrespective of random swimming activity change. The AQ of normoxic and hypoxic mullet showed opposing trends, the quotient increasing with decreasing activity in the former and increasing with activity increase in the latter. The AQ change suggests increased protein utilization in quieter fish when adequate ambient oxygen is available, but the hypoxic mullet utilizes more protein the more active it is. The latter change in AQ is consonant with the change in hypoxic RQ and it is likely that increased anaerobic energy utilization demanded by the increased activity is accompanied by increased protein breakdown and ammonia release, thereby helping in acid-base balance and ionic (Na+) regulation. Results obtained at 30 and 35°C are almost identical. Within the small range temperature does not seem to cause a marked metabolic difference in mullet.

    • Energy utilization in freshwater mullet,Rhinomugil corsula (Hamilton) under exercise

      N Sukumaran M N Kutty

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      Energy utilization in mullet,Rhinomugil corsula, exercised continuously for 5 h at different swimming speeds ranging between 20 and 77 cm s−1 was studied in a tunnel type apparatus. Oxygen consumption, carbon dioxide output and respiratory quotient decreased with increase in the duration of exercise. The initial (1st h) respiratory quotient, which was always above unity, increased with intensity of swimming speed, but the steady (5th h) respiratory quotient remained below unity, at about the same level irrespective of the increase in activity.

      Nitrogen (NH3 and total) excretion, ammonia quotient and nitrogen quotient increased with both duration and intensity of exercise, indicating the increased protein utilization during the later phase of exercise.

      An attempt has been made to estimate the relative energy derivation from different substrates with some assumptions for the entire 5 h of exercise at 20 and 77 cm s−1. At 20 cm s−1 the energy derived aerobically from proteins, carbohydrates and fats and that from anaerobic source (carbohydrate) were estimated as 13040·3, 1378·2, 2367·3 and 1048·5 J kg−1 fish, being 73·1, 7·7, 13·3 and 5·9% of a total of 17834·3 J kg−1 fish, whereas at a swimming speed of 77 cm s−1 it was estimated as 33587·9, 2841·4 and 1305·4 J kg−1 fish from proteins, fats and anaerobic source respectively, being 89·0, 7·5, 3·5% of a total of 37734·7 J kg−1 fish.

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