Agricultural Science


  • This is based on nutrient composition:
  • Feed additives.


Are feeds of low available nutrients per unit weight and high fibre content


  • Dry roughages,
  • Succulent roughages,
  • Residues from agricultural by products and conserved materials.


  • Low level of available nutrients.
  • Have high level of calcium especially legumes.
  • Good source of vitamin A.
  • Have high fibre content.


Are feeds of high available nutrients per unit weight.


  • Maize germ and bran,
  • malt extract,
  • milk products,
  • soyabeans,
  • oil seed cakes,
  • meat meal,
  • bonemeal


  • Low fibre content.
  • Feed content is consistently high.
  • High digestibility of the feed.
  • High in nutrient content.

Feed Additives

  • These are substances added to the feed to increase;
  • palatability,
  • medication
  • or hormones to make animals produce more.

There are two types:

  • Nutritive additives, such as mineral licks (maclick).
  • Non-nutritives additives, such as:

– medicants (coccidiostats),

– Stilboestrol (used in beef animals)

– Oxytocin (to increase milk let down).


  • Stimulate growth and production.
  • Improve feed efficiency.
  • Prevent disease causing organisms.

Compounded Feeds

  • These are the feeds prepared and mixed by use of machines.
  • These feeds can be round, pelleted, pencils, cubes or mash.

Poultry feeds can be categorized as:

  • Chick mash having 20% D.C.P. given to chicks.
  • Growers mash having 16% D.C.P. given to growers.
  • Layers mash having 12-15% D.C.P. given to layers.

Meaning of terms used to express feed values

Nutritive ratio (NR):

–  ls the proportion of protein to carbohydrates and fats.

– In young animals 13:6

– In old animals 1:8.

Crude protein (C.P): ls the total amount of protein contained in a feed.

Digestible Crude Protein (D.C.P): Is the portion of crude protein which an animal is capable of digesting.

Crude Fibre (C.F.):

–  ls the total amount of fibre contained in a feed.

–  It is mainly lignin and cellulose.

Digestible Fibre (D.F.): ls the portion of the total fibre contained in a teed which an animal is capable of digesting.

Dry Matter (D.M.): ls the material left in a feed after water has been removed.

Starch equivalent (S.E.): ls the amount of pure starch which has the same energy as 100kg of that feed.

Total Digestible Nutrients (T.D.N.): ls the sum of all the digestible organic nutrients such as fats, proteins, carbohydrates and fibre.

Author: Egbinola F

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