Nutritional value of flaxseed meal for swine and its effects on the fatty acid profile of the carcass1

Abstract

Four experiments were conducted to determine the nutritional value of flaxseed meal [FSM; 133 g of ether extract (EE) and 343 g of CP/kg of DM] for swine. In Exp. 1, apparent fecal digestibility (AD) of DM and EE, and the DE and NE contents were determined in growing pigs (n = 32; initial BW, 70 +/- 3 kg) and gestating sows (n = 24; parities, 2 to 4). Diets contained 0, 100, 200, or 300 g of FSM/kg at the expense of wheat, barley, and soybean meal. Fecal samples were collected for 3 d after a 9-d adaptation. The AD for DM and EE were 72.0 +/- 0.4% and 67.4 +/- 4.7%, respectively, for growing pigs and 68.0 +/- 0.5% and 48.9 +/- 1.9% for sows. The DE content was 3.51 and 3.54 Mcal/kg for growing pigs and gestating sows, and NE was estimated to be 2.43 and 2.44 Mcal/kg for growing pigs and sows, respectively. Five ileally cannulated barrows (initial BW, 38 +/- 3 kg) were fed semi-synthetic diets containing 400 g of FSM/kg for a 7-d period (4-d adaptation and 3-d collection) then 7 d of N-free diet to determine basal endogenous N losses in Exp. 2. Standardized ileal digestible AA contents were 29.6 +/- 1.0, 5.7 +/- 0.3, 12.1 +/- 0.8, 16.8 +/- 1.0, 10.3 +/- 0.4, 5.3 +/- 0.3, 14.0 +/- 0.7, 9.4 +/- 0.5, 2.9 +/- 0.2, and 13.8 +/- 0.8 g/kg of dry FSM for Arg, His, Ile, Leu, Lys, Met, Phe, Thr, Trp, and Val, respectively. In Exp. 3, the AD of P and the effects of phytase inclusion on P availability were determined. Five groups of 8 barrows (initial BW, 45 +/- 4 kg) were fed a 300 g of FSM/kg semi-synthetic diet with increasing concentrations of exogenous phytase [0, 575, 1,185, 2,400 and 2,570 phytase units (FTU)/kg]. The AD of P increased from 21 to 61% (P < 0.001). Broken-line analysis estimated the optimal phytase inclusion rate to be 1,415 FTU/kg of diet. Growth performance and carcass fatty acid (FA) profiles of pigs fed FSM were determined in Exp. 4. Two hundred pigs (100 barrows and 100 gilts; initial BW, 32 +/- 4 kg), blocked by sex, were housed in groups of 5 pigs per pen and fed 1 of 4 diets containing 0, 50, 100, or 150 g of FSM/kg. Six market pigs per diet were selected for carcass FA analysis. The ADG, ADFI, and G:F were not affected by dietary FSM (P > 0.05). Increasing FSM in the diet from 0 to 150 g of FSM/kg increased the alpha-linolenic acid content from 11.1 +/- 0.2 to 47.4 +/- 1.2 mg/g of backfat (P < 0.001) and from 5.0 +/- 0.1 to 10.1 +/- 0.6 mg/g of loin tissue (P < 0.001). Flaxseed meal despite its deficiency in lysine can be included up to 150 g/kg of diets for swine and will contribute to the enrichment of the carcass with n-3 fatty acids.