Nitrogen Metabolism in the Young Sow

The establishment of quantitative relationships between nitrogen (N) retention and energy and protein intake in breeding animals is essential to enable producers to determine the consequences of altering nutrient intake on changes in body composition, reproductive efficiency and lactational performance. Results of an experiment with pregnant gilts revealed that maximum rates of N retention occurred at 0.58, 0.55 and 0.66 g lysine/MJ DE during early, midand late pregnancy respectively. Furthermore, the relationship between N retention and energy intake was linear over the range in dietary energy intakes normally encountered in commercial pig production. Results of a lactation study emphasised the need to relate nutrient requirements of the lactating sow to the production levels attained by the sow. Sows required a diet containing 0.85g lysine/MJ DE during their first lactation to maximise N conservation. However, maximum lactational performance appeared to occur at lower levels of dietary protein.