PSIII-17 Inducing trans-10-shifted biohydrogenation pathways improves feed conversion efficiency and carcass quality in feedlot lambs.

Abstract We previously found a negative association between the backfat concentrations of trans-10 biohydrogenation intermediates, trans(t)10-18:1, and the USDA yield grade in feedlot lambs. This study aimed to evaluate the causal effects of inducing t10-shifted biohydrogenation pathways by feeding a grain-based diet supplemented with high linoleic acid corn oil on growth performance and carcass characteristics in feedlot lambs. Twelve Dorper (BW=37.57±17.04 kg) and 12 Dark-faced Suffolk x Hampshire/Hampshire x Dorset (BW=41.82±18.97 kg) lambs were used in a completely randomized block design with breed as the block. Within each block, lambs were randomly assigned to one of three diets: a control diet (CTL, no fat supplement), a grain- based diet containing 6% palm oil-based saturated fat supplement (PAL), or a grain-based diet containing 6% high-linoleic corn oil (COR) for 35 days. Individual feed intake was recorded daily, and body weight measured weekly. Plasma samples were obtained on days 0, 18, and 35 for fatty acid analysis. Backfat thickness was measured on days 0 and 35 using ultrasound. The lambs were processed at the Superior Farms plant and graded with a USDA-inspected camera grading system. Data were analyzed using the PROC MIXED procedure in SAS. Plasma concentration of t10-18:1 was higher (P < 0.05) in COR (5.61%) compared to CTL (1.40%) and PAL (2.18%). The t10:18-1/t11:18-1 was lower (P < 0.05) in CTL (0.79) than both PAL (2.84) and COR (3.97). Final body weight (50.35±5.76kg) and body weight gain (10.73±1.92kg) did not differ among treatments (P > 0.05). COR had lower (P = 0.0311) average daily dry matter intake than PAL but was not different from CTL (1.35±0.44 kg, 1.53±0.51 kg, 1.50±0.37 kg, respectively). The feed-to-gain ratio was lower (P = 0.0108) in COR (1.90) compared to CTL (2.32) and PAL (2.34), indicating that the COR group had the best feed efficiency among the treatment groups. PAL diet resulted in increased (P = 0.0472) backfat thickness compared to CTL (10.11±2.08 mm and 7.37±2.43mm, respectively), but no increase (P > 0.10) was observed in the COR (8.32±1.98 mm). Moreover, hot carcass weight was significantly greater in COR (26.72kg) compared to CTL (25.15kg) but was not different from PAL (26.93kg). No differences (P > 0.05) were observed in yield grade or loin area gain (P > 0.05) among treatments. Overall, our data suggest that inducing trans-10-shifted pathways can improve feed efficiency and carcass quality in feedlot lambs. Long-term studies with a larger sample sizes are needed to verify these findings.