Table 1.

Comparison between the productive parameters of the elite modern lactating sow and the reference sow of the past

	1985a	2012b
Item	Average sow	Average sow	Elite sowc
Total pigs born, n	11.2	13.4	15.1
Pigs weaned,d n	8.6	10.3	11.5
Litter gain,e kg/d	1.60	2.09	2.35
Milk production,f kg/d	6.9	8.2	9.2
Nutrient output,f g/d
Lactose	385	458	512
Protein	379	450	501
Fat	526	626	699

^aSource: [2, 3]

^bSource: [1]

^cTop 10 % of farms

^dLactation length: average sow 1985 = 25.1, average sow 2013 = 20.5, and elite sow 2013 = 22.3 d

^eFor the average sow of 1985, litter gain estimation used information provided by Noblet and Etienne [3]

^fMilk production and nutrient output was calculated based on litter weight gain and litter size at weaning using a set of equations derived from Hansen et al. [40]