This question was fairly attempted by the candidates.  In 7(a)(i), many candidates could
explain the terms line breeding and inbreeding as used in animal improvement.  Further
to this, in 7(b) and (c), majority of the candidates were able to mention the factors that
determine the amount of water required by farm animals and; sources of calcium in the
diet of livestock.

However, in 7(a)(ii), many candidates could not state the advantages and disadvantages
of inbreeding in animal improvement.

The expected answers include:

Advantages and disadvantages of inbreeding

 Advantages

• Inbreeding increases homozygosity, as the number of desirable genes in common increases in every generation
• Brings undesirable recessives  to light and gives the breeder the opportunity of culling them from the stock
• It separates the population quickly into families and this offers more opportunity for selection of certain traits

Disadvantages

• It causes a decline in fertility and an increase in mortality, thus leading to  a decline in productivity
• It requires skill in making planned matings and rigid selection
• It is not adapted for use by the farmer with average or below average stock, because undesirable genes express themselves
• It lowers the average merit of the population by reducing heterozygosity
• There is inbreeding depression resulting in degeneration or decline in offspring, especially in traits like milk yield and egg production