1897
Effect of method of flaxseed processing and tannins on the growth performance and carcass fatty acid profile of lambs
The objective of this study was to evaluate the effect of flax, method of processing, and tannin inclusion on the growth performance of feedlot lambs and the carcass fatty acid composition. Forty Suffolk × Arcott lambs (22 females and 18 males) with an initial BW of 37.7 ± 5.87 kg were assigned to 1 of 2 blocks and within block to 1 of 5 dietary treatments in a randomized complete block design. Treatments (DM basis) were 1) CONT, a diet containing 15% barley silage, 53.6% ground barley, 11.9% canola meal, 6.4% alfalfa dehydrated, 4.0% oat hulls, 3.7% beet pulp, 3.3% fat and 2.1% mineral supplement; 2) FLAX, inclusion of 8.6% flaxseed; 3) FLAX+T, inclusion of 8.6% flaxseed and 4% tannins; 4) EF, inclusion of 20.5% extruded flaxseed; 5) EF+T, inclusion of 20.5% extruded flaxseed and 4% tannins. At the end of the 60 d study, ruminal fluid, blood, longissimus dorsi (LM), and subcutaneous back fat samples were collected and analyzed for fatty acid composition. Fatty acids were expressed as percentage of total fatty acid methyl esters. Data were analyzed as a randomized complete block design using the MIXED procedure of SAS. Treatment did not affect final BW (P = 0.60) or ADG (P = 0.36) with averages of 55.3 ± 3.10 kg and 324.0 ± 29.75 g/d, respectively. The proportion of saturated fatty acids in ruminal fluid (P < 0.01) and plasma (P < 0.05) was greatest in lambs fed CONT and CONT had the lowest (P < 0.01) proportion of polyunsaturated and omega-3 fatty acids in plasma. The proportions of saturated (P = 0.93) and polyunsaturated (P = 0.15) fatty acids in LM were unaffected. However, lambs fed FLAX+T, EF or EF+T had the greatest (P < 0.01) proportion of omega-3 fatty acids, with a minimum of a 2.3 fold greater concentration (P < 0.01) than CONT. The proportion of polyunsaturated fatty acids in subcutaneous fat was greatest (P < 0.01) in lambs fed FLAX+T or EF+T. Lambs fed FLAX+T had the greatest (P < 0.01) concentration of omega-3 fatty acids in subcutaneous fat with an estimate of 3.13 ± 0.189%: a value 3.3 fold higher (P < 0.01) than CONT. Overall, the fatty acid profile of lamb was improved when flaxseed or extruded flaxseed was fed without affecting growth performance. Tannins had minimal additional effects on carcass fatty acid profile.
Keywords: Extrusion, flaxseed, omega-3 fatty acids