By Mariana Menegat, Carine Vier, Steve Dritz, Mike Tokach, Jason Woodworth, Joel DeRouchey and Robert Goodband, Kansas State University
The nutrient requirements of growing pigs generally decrease over the growing-finishing period. In commercial production, phase feeding is used to closely meet the nutrient requirements of grow-finishing pigs compared to feeding fewer phases. The lysine requirement is the core component of developing feeding strategies for grow-finish pigs, because lysine is the first limiting amino acid in typical swine diets and is involved in growth performance and lean deposition. This study was developed to compare phase feeding strategies for grow-finish pigs using different lysine specifications.
In this experiment, 1,188 pigs initially 61.5 pounds body weight were assigned to feeding programs until market weight (284.5 pounds). The phase feeding programs were based on estimated lysine requirements for maximal growth rate and feed efficiency (PIC, 2016) or on standard lysine requirements for optimal income over feed cost (adapted from Tokach et al., 2012). The phase feeding programs consisted of: (1) MAX, a four-phase feeding program with lysine levels for maximum growth (1.13, 0.96, 0.82, 0.77% SID Lys in Phases 1 to 4, respectively); (2) STD, a standard four-phase feeding program for optimum income over feed cost (1.02, 0.87, 0.76, 0.67% SID Lys in Phases 1 to 4, respectively); (3) STD/MAX, a four-phase feeding program with standard lysine levels in early finishing and lysine levels for maximum growth in late-finishing (1.02, 0.87, 0.82, and 0.77% SID Lys in Phases 1 to 4, respectively); and (4) Two-phase, a two-phase feeding program based on the average lysine levels for maximum growth in Phases 1, 2 and 3 (0.96% SID lysine) and 0.77% SID lysine in Phase 4. Lysine levels in the diets were achieved by changing the corn-to-soybean meal ratio.
Over the grow-finish period, the two-phase feeding program increased average daily gain compared to the standard four-phase feeding program (two-phase versus STD, respectively), and either the four-phase regimen for maximum growth or the combination of standard in early finishing and maximum in late-finishing, resulted in intermediate average daily gain (MAX and STD/MAX, respectively; Figure 1).
These findings demonstrate that feeding finishing pigs in either a two- or four-phase feeding program (Two-phase or MAX) results in similar growth performance, which allows for the possibility and practicality of using fewer feeding phases in the grow-finish phase. From an economic standpoint, lower feed cost per pound of gain was achieved by feeding the standard four-phase feeding program (STD; Figure 2), but income over feed cost was similar across feeding regimens (Figure 3).
In summary, feeding lysine levels for maximum growth and efficiency in either a two- or four-phase feeding program results in similar growth performance and feed cost. Formulating grow-finish diets to the range of lysine levels tested in this study do not compromise income over feed cost regardless of phase-feeding strategy.
1 PIC. 2016. Nutrient Specifications Manual.
2 Tokach, M. D., DeRouchey, J. M., Dritz, S. S., Goodband, R. D., and Nelssen, J. L. 2012. Amino acid requirements of growing pigs. Proceedings of Swine Profitability Conference, Manhattan, Kan.