Riboflavin supply strategies in male turkey production including either supply of alfalfa silage or free-range access in organic farming

Abstract

Abstract The objective of this study was to determine an optimal riboflavin supply strategy for an organically reared and fattened male fast-growing turkey line including supply of silage and free-range access. A total of 768 one-day old B.U.T. 6 turkey poults were allocated to one out of four riboflavin supply strategies and raised in 5 feeding phases (P1-P5). In each phase, concentrate based diets were formulated with different riboflavin contents. In the “Low” diet (L) riboflavin content was according to the NRC/GfE riboflavin recommendations (4.0, 4.0, 2.9, 2.4 and 2.4Â mg/kg diet in P1-P5) and the “High” diet (H) it was twice the level of the L diet. In the rearing (P1Â +Â P2) and fattening period (P3-P5) animals received either the L or H diet resulting in 4 riboflavin supply strategies (LL, LH, HL and HH). From day 56 (P3-P5) different feeding strategies were provided: concentrate based diets only (C), C with additional alfalfa silage (C+Si) or C with free-range access to pasture (C+Pa). Results showed that the riboflavin strategy had no influence on growth and slaughter performance or on the liver measurements (PÂ >Â 0.05). As compared to C, supplemental silage or free-range access decreased the total concentrate feed intake by about 5Â kg (8%) and 10Â kg (16%) for the C+Pa and C+Si groups, respectively (PÂ <Â 0.05). However, at day 140 final body weights of all treatments were on a high level. The dressing percentage of all groups was equal, but the breast muscle portion of the C+Pa treatment was significantly higher than in the other groups (PÂ <Â 0.05). In conclusion riboflavin recommendations on the level of NRC/GfE are sufficient for fast growing male turkeys in organic farming systems. High performance levels can be realized using supplemental alfalfa silage or pasture from free-range access with a simultaneous reduction in concentrate feed intake.