• S Mathavan

      Articles written in Proceedings – Animal Sciences

    • Utilization of dietary protein, fat and carbohydrate by the paddy field fish (Macropodus cupanus: Anabantidae)

      S Mathavan M S M Christopher

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      Preferential utilization of protein, fat and carbohydrate by different weight classes ofMacropodus cupanus was studied exposing the fish to algal, animal and combined feed. Consumption and conversion of protein and fat was maximum in the liver fed group. At maximum feeding the small fish converted carbohydrate, fat and protein at an efficiency of 9.45, 26.55 and 18.29% respectively. The efficiency of conversion decreased with increasing body weight. At all feeding schedules carbohydrate was converted more or less efficiently. The fish exposed to minimum animal feed or 100% algal feed utilized almost equal amount of stored protein cr fat for maintenance metabolism.

    • Population dynamics of a tropical lepidopteranCatopsilia crocale (Pieridae)

      M S M Christopher S Mathavan

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      Extensive field observations were undertaken to study the population dynamics of the larvae ofCatopsilia crocale in the Madurai Kamaraj University campus during the years 1980–81 and 1981–82. Though oligophagous,C. crocale adopted ‘monophagic strategy’ for oviposition and larval feeding. Seasonal changes in the nitrogen content of the foodCassia alata leaf influenced the pupal/adult weight and oviposition. Commencement of rain triggered the reproductive activity and continued precipitation facilitated maximum egg deposition. Of total egg production in a year, about 80% was oviposited during northeast monsoon (September–December) and the rest during the south-west monsoon (May–August). Egg, I instar, V instar and pupa suffered more mortality than the other life stages. Of the total number of eggs laid, about 1·01% emerged as adult and 98·99% died during the process of larval and pupal development.

    • Effect of temperature and host seed species on the fecundity ofCallosobruchus maculatus (F.)

      J Chandrantha J Muthukrishnan S Mathavan

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      Callosobruchus maculatus was reared onVigna unguiculata, Phaseolus radiatus andDolichos lab lab from hatching to death at 20, 25, 30 and 35°C. Food consumption, growth and egg production were estimated in terms of energy. At the tested temperatures, host seed species significantly influenced feeding and energy allocated to egg production. Irrespective of the seed species, food consumption decreased with increasing temperature. Energy density of an egg did not vary with seed species but significantly decreased with increasing temperature. Fecundity (egg/females) ofCallosobruchus maculatus ranged from 73 onD. lab lab at 35°C to 118 onVigna unguiculata at 30°C. Energy allocated to egg production at 20°C was more than at other temperatures. A statistically significant inverse relationship exists between overall feeding rate ofCallosobruchus maculatus and energy allocated to egg production.

    • Effects of feeding regime on energy allocation to reproduction in the silkwormBombyx mori

      S Mathavan G Santhi B Nagaraja Sethuraman

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      Pattern of energy allocation for reproduction was studied as a function of feeding regimes in the silkwormBombyx mori. The larvae were restricted to feed for 6, 12, 18 or 24 h (ad libitum). Restriction of feeding duration resulted in slow growth and extended larval duration. Consumption, assimilation, conversion and metabolism and their rates showed steady increase with the increase in the feeding duration. On pupation, energy allocation for egg production was studied by dissecting the pupa and estimating the reproductive and body tissues separately during the entire pupal period. Length and biomass of ovary steadily increased with increasing feeding duration as well as with increasing age of pupa. During egg development, the tissue protein was transferred to the ovary. This type of conversion was more in those fedad libitum than in those restricted to feed for shorter durations. Tissue fat and ovarian fat decreased as a function of age of pupa, indicating that fat served as the main source of energy for pupal metabolism.Bombyx mori restricted to feed for 6 h duration allocated 55% pupal energy for reproduction while those fedad libitum allocated about 67% of the pupal energy for reproduction. However, they allocated about 15–19% of assimilated energy for egg production in all the feeding regimes.

    • Nitrogen budget ofCallosobruchus maculatus larva developing in different host seed species

      J Chandrakantha S Mathavan J Muthukrishnan

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      Studies on effect of seed species and their interacting influence on food utilization ofCallosobruchus maculatus clearly pointed out that rates and efficiencies of nitrogen utilization are determined by the composition of the seed also. Of the 3 species of seeds tested,Vigna unguiculata has significantly more nitrogen and water per unit weight than the other two seeds,Dolichos lab lab andPhaseolus radiatus. With increasing nitrogen content of the seed, rates of feeding, assimilation and metabolism decreased. On the other hand efficiencies of assimilation and net production increased. Nitrogen assimilation efficiency ofCallosobruchus maculatus ranged from 76·6% inDolichos lab lab to 85·8% inVigna unguiculata. The efficiency of accumulation of assimilated nitrogen was around 82%. The less nutritiousDolichos lab lab contributed more to the observed variance in the efficiencies of assimilation and production. The low efficiencies may be attributed to the presence of protease inhibitors.

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