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Table 5 Apparent utilization efficiency of nitrogen and energy of sows fed Control (CON; 187.4 g/kg crude protein), Optimal (OPT; 137.8 g/kg crude protein) or Optimal + Leucine (OPTLEU; 142.5 g/kg) diets between day 4 and 8 of lactation (early lactation) and between day 14 and 18 of lactation (peak lactation)1

From: Reduced protein diet with near ideal amino acid profile improves energy efficiency and mitigate heat production associated with lactation in sows

Early lactation (day 4 to 8)
 Number of sows121111    
Nitrogen (N) utilization efficiency3
 Milk N output/ME intake, g/MJ40.880.900.940.060.9600.7590.907
 Milk N output/NE intake, g/MJ41.
Energy utilization efficiency
 Total energy retention, % of energy intake55.153.350.81.60.7030.1630.537
 Total energy retention, % of energy absorbed62.661.559.61.60.8470.2980.606
 Milk energy output, % of energy intake49.555.
 Milk energy output, % of energy absorbed56.263.463.64.40.4610.4420.999
Peak lactation (day 14 to 18)
 Number of sows111111    
Nitrogen (N) utilization efficiency3
 Milk N output/ME intake, g/MJ40.861.05*0.930.060.0880.6600.384
 Milk N output/NE intake, g/MJ41.141.38*
Energy utilization efficiency
 Total energy retention, % of intake63.2*62.8*58.6*1.60.9860.1400.187
 Total energy retention, % of absorbed71.8*72.2*69.1*1.60.9730.3690.265
 Milk energy output, % of energy intake44.562.353.03.70.0070.2680.199
 Milk energy output, % of energy absorbed50.771.562.24.40.0060.1670.304
  1. 1Data are least squares means
  2. 2Maximum value of the standard error of the means
  3. 3Milk N = Milk true protein × 6.25 + milk urea N
  4. 4The ME and NE intake were based on calculated values of ME and NE
  5. *Main effect of period (early and late) was significant (P < 0.05)