A reference unit which facilitates the aggregation of livestock from various species and age as per convention, via the use of specific coefficients established initially on the basis of the nutritional or feed requirement of each type of animal (see table below for an overview of the most commonly used coefficients).
The reference unit used for the calculation of livestock units (=1 LSU) is the grazing equivalent of one adult dairy cow producing 3 000 kg of milk annually, without additional concentrated foodstuffs.
LU’s as derived from the LUCAS land use nomenclature (http://ec.europa.eu/eurostat/ramon/other_documents/lucas/index.htm):

Bovine animals
Under 1 year old 0,400
 1 but less than 2 years old  0,700
Male, 2 years old and over 1,000
Heifers, 2 years old and over 0,800
Dairy cows 1,000
Other cows, 2 years old and over 0,800
Sheep and goats 0,100
Equidae 0,800
Pigs Piglets having a live weight of under 20kg 0,027
Breeding sows weighing 50kg and over 0,500
Other pigs 0,300
Poultry Broilers 0,007
Laying hens 0,014
Ostriches 0,350
Other poultry 0,030
Rabbits, breeding feemales 0,020