Amino Acid Requirements of Sows Nursing 13 to 14 Piglets

Selection for high prolific sows has increased the requirements for dietary protein, AA and energy. However, optimal daily supply to sows in farrowing units is challenging because most farms use the same diet during the last 5 to 7 days before parturition and until weaning around 4 weeks of age. Factorial calculations indicate that protein, lysine, and energy may be the limiting factor for sow productivity depending on the physiological stage. We have used different approaches to quantify how nutrients are utilized by late-gestating and lactating sows with the final aim of improving sow yield of colostrum and milk or minimizing body mobilization. For that purpose, two multi-catheterized sow models have been established; the first model to allow quantification of net portal uptake and net hepatic clearance of metabolites including AA and the second model to compare mammary uptake of AA with AA secreted into milk. Both studies indicated that intermediary metabolism of sows changed greatly from 3 days prior to parturition to 3 days after parturition. Furthermore, the studies suggested that sows lacked energy in early lactation more than dietary AA or dietary protein, whereas lysine limited the milk production at peak lactation. To match the rapid changes in daily requirements for lysine, protein and energy in early lactation, two other experiments have been conducted using 2-component feeding strategies. The 2 components were formulated to contain low and high standardized ileal digestible (SID) lysine per unit of ME to better match the requirements for maintenance and milk production, respectively, and the sows responded by producing more milk and/or by reducing the body mobilization of energy. Optimal daily protein requirement is less easy to evaluate as the loss of nitrogen via urine depends on the protein intake, the energy intake, the AA profile of the diet, and the live weight of the sow. In conclusion, major changes in nutrient requirement of sows occurred when housed in farrowing units and using a 2-component feeding strategy seems to be a promising approach to increase milk yield and/or reduce mobilization of body nutrients from lactating sows because the daily supplies of lysine and energy may be partly separated.