Previous models to calculate sow requirements were mainly focused on the gestation or lactation periods without paying attention to the changes that occur during the transition period. Therefore, precision and understanding may be enhanced if traits describing this changing period are also taken into account. This study aimed to quantify daily requirements for metabolizable energy (ME) and standard ileal digestible (SID) lysine in late gestating and lactating sows using a factorial approach. Metabolizable energy and SID lysine required for foetal and mammary growth, colostrum and milk production, uterine components (including uterus wall, placenta and membrane fluids) and maintenance were estimated.
It was estimated that maintenance, additional heat loss, colostrum production, fetal growth, mammary growth and uterine components accounted for 66.8%, 19.3%, 7.2%, 5.0%, 1.3% and 0.5% of total ME requirements, respectively, in the last 12 days of gestation. Oxidation/transamination, fetal growth, mammary growth, colostrum production, maintenance and uterine components were estimated to account for 29.5%, 22.7%, 16.8%, 16.1%, 10.4% and 4.5% of total SID lysine requirements, respectively, in the last 12 days of gestation. After parturition, ME and SID lysine requirements increased daily until peak lactation (day 17). At peak lactation, 95% and 72% of total required SID lysine and ME, respectively, were associated with milk production (including oxidation). Relative to day 104 of gestation, ME and SID lysine requirements increased by 60% and 149% at day 115 of gestation, and by 228%, and 338% at peak lactation, respectively. A dietary SID lysine: ME ratio of 0.55 was estimated as the ideal ratio to optimize milk production at peak lactation. It was estimated that the regressing uterus released about 30 g SID lysine and 14 MJ ME into the endogenous plasma pool during lactation. It was concluded that dramatic changes in nutrient requirements and nutrient balances take place during transition and lactation and both, live weight and milk yield substantially affects the amount of energy and lysine required during transition and lactation. Sows with a high milk yield require feed with a high SID lysine: ME ratio whereas sows with a high live weight require feed with a lower SID lysine: ME ratio. Therefore, feeding strategy with two components will likely enhance sow productivity in the future.
Feyera, T., & Theil, P. K. (2017). Energy and lysine requirements and balances of sows during transition and lactation: A factorial approach. Livestock Science, 201, 50-57. https://doi.org/10.1016/j.livsci.2017.05.001