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Economic trade-offs between milk and meat production under various supplementation levels in Botswana

Year of publication 1983

Place of publication Rome, Italy ;

Product type Book (stand-alone)

Series title ILCA Research Report

Series number 0257-8409

Edition 1

Language English

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    Project
    Production, yield characteristics and economics of polyculture of Macrobrachium rosenbergii and various fish species under pond condition
    Establishment of a Network of Aquaculture Centres in Asia
    1986
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    The effect of two densities of freshwater prawn Macrobrachium rosenbergii on production,yield eristics and economics under polyculture system were examined in four ponds of 1.75 rai each during seven months growing period.Prawns stocked at about 2 (L.D) and 5 (H.D) tails per sq.m with the average weight of 3–4 g.Fish stocked in each ponds are as follows:225,500,350 and 1250 tails per pond for common carp,giant gouramy,bighead and silver carp respectively.The average production of fish in L.D and H.D amounted to 2,295 and 2,125 kg per ha respectively.Common carp had a highest growth,while silver carp and bighead were the lowest.There was an indication that the production in H.D was higher.The average production of prawn in L.D and H.D reached 722 and 910 kg per ha.It is considered that the stocking rate of common carp should be lower,since the pond productivity was not enough to support the growth of silver carp and bighead carp.It is observed that the production of fish was not affecte d by the different stocking densities of prawn.The survival rate of common carp was the highest(92%),followed by bighead carp (83%& 93%),silver carp (89% & 80%)and giant gouramy (76%& 73%).For the prawn it ranged from 49.1–61.1%,except one replicate in L.D which comprised 95%. This may probably be due to second restocking. The F.C.R of fish,based on the F.C.R of prawn (2.5),were 0.85 and 1.12 respectively in L.D and H.D.The average weight (g) of male prawn ranged widely in each category (43–102 g) compared to female prawn (29–51 g). The percentage in number of female prawn ranged 65–72% in both L.D and H.D. There is a positive relationship between stocking density and the percentage both in number ans weight of female prawn as well as the marketable yield. The marketable yield comprised about 87% of total biomass both in L.D and H.D.***
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