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 Agricultural Science Paper 2, Nov/Dec 2009
 Questions: 1 2 3 4 5 6 7 8 9 10 Main
General Comments
Weakness/Remedies
Strength

Question 8

(a)    Explain the term fodder as used in animal nutrition.                          [ 2 marks]
(b)    State four functions of water in farm animals.                                     [ 4 marks]
(c)    State five objectives of animal improvement programmes.                 [4 marks]
(d)     If the size of a fish pond is 40m x 21 m and the stocking rates of Tilapia spp. and catfish
fingerlings are 2.0 per m2 and 1.0 per m2 respectively.

Calculate the:

1.  population of Tilapia spp. and catfish needed to stock the pond;     [2 marks]
2. yield at harvest if the mortality rates of Tilapia spp. and catfish

are 5.0% and 3.0% respectively;                                                         [2 marks]

1. yield at harvest in tonnes, if the average live weights of Tilapia spp.

and catfish are 600g and 1.5 kg respectively.                                       [2 marks]

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OBSERVATION

This question was poorly attempted by the candidates.   In 8(a), many candidates could not explain the term fodder as used in animal nutrition.  However, in 8(b) and (c), many candidates were able to state functions of water in farm animals and objectives of animal improvement programmes in West Africa.  In 8d( i – iii), majority of the candidates could not carry out the required calculations on fish pond stocking with Tilapia spp. and catfish fingerlings.
The expected answers include:
Explanation of the term fodder as used in animal nutrition:
Fodder is freshly harvested grass or legume fed to animals.
Calculation on the population of Tilapia spp.and catfish needed to stock the pond.
Population of Tilapia spp.and catfish.
= size of the pond x stocking rate of each species/m2
=   (40 x 21)m2 x 2                           (Tilapia spp.)
m2

=  840 x 2 = 1,680 fingerlings of Tilapia spp.
Catfish
=   (40 x 21)m  x 1 = 840
m2
= 840 fingerlings of catfish
Yield at harvest
Tilapia spp. mortality  =  5%
=        5 x 1680    =   84 (mortality number)
100      1

Tilapia spp. yield at harvest
= Total yield – Mortality number

=  1,680 – 84
=  1,596 Tilapia spp.

Catfish mortality  =  3%
=   3  x  840   =     25 (mortality number)
100      1

Catfish yield at harvest
=   Total yield – Mortality number
840  -  25
=  815 catfish

(iii)      Yield at harvest in tonnes

Average  live weight of tilapia spp.
=  600g

1,596 x 600g
=  957600g

1000g = 1 kg
957600g = 957.6kg
1000g

1000kg  =  1 tonne
957.6 tonnes
1000 kg

=  0.9576 tonnes
= 0.96 tonnes

Catfish
Average liveweight of catfish
= 1.5. kg
815 x 1.5kg
=   1222.5 kg
1000kg = 1 tonne
1222.5kg
1000 kg

=  1.2225 tonne
=  1.22 tonnes

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