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A total of 72 lactations lasting for 28 days of multiparous sows were distributed into six dietary treatments. The basal diet (1.2 g Trp/kg, 0.8 g/kg apparent ileal digestible, AID) was supplemented with 0; 0.3; 0.6; 1.2; 1.8 or 3.0 g of crystalline L-Trp/kg, resulting in six diets with increasing Trp AID content of 0.8, 1.1, 1.4, 2.0, 2.6, and 3.8 g/kg. Parameters measured were feed intake and body weight loss of the sows, weight of the litters (days 1, 21 and 28), milk output, protein and milk protein output, fat and milk fat output, and lactose in milk. Dietary nutrient concentrations, nutrient digestibility and ileal digestibility of aminoacids in lactation feed were determined in a parallel study.
Results showed that feed intake of the sows increased quadratically (maximum for treatment 4, diet presenting 2.0 g AID Trp/kg diet), and the body weight loss showed a linear and a tendence to quadratic response, being the lowest body weight lost found in the treatment 4. In the same way, daily milk production showed a quadratic response (maximum for treatment 4). However, neither the contents in protein, fat or lactose in the milk were affected by dietary treatments. The data of total litter weight demonstrated no differences on day 21, but a linear effect on day 28.
The Trp content in diet for lactating sows nursing 10-12 piglets of 1.9 g apparent ileal digestible Trp/kg (increase of 37% in the NRC recommendations) is recommended to obtain a proper feed intake and to prevent impairments of performance with regard to milk yield and piglets growth rates.
Paulicks, B. R., Pampuch, F. G., Roth-Maier, D. A. (2006) Journal of Animal Physiology and Animal Nutrition 90: 474-481
