| Five ruminally and duodenally cannulated Angus heifers were used in a5x5Latin square with2×2+1factorial arrangement to determine the effects of increasing inclusion of corn dried distillers grain with solubles (DDGS) and monensin (Mon) supplementation on rumenal fermentation, energy metabolism, fatty acid metabolism by determined pH, volatile fatty acid (VFA), nitrogen metabolism and biohydrogenation in rumen and nutritions flow. The results showed that:intake of dry matter (DM) tended to be less (P<0.10), and ruminal degradability of crude protein (CP) was less (P<0.01), but the total digestibility of CP was greater (P<0.01) for corn DDGS than for the control diets. With increasing corn DDGS inclusion (0,20%,40%) in diets, flow of organic matter (OM) to duodenum was increased (P<0.05), ruminal digestibilities of OM, neutral detergent fiber (NDF) and??were linearly (P<0.01) decreased, but the total digestibility was not different, total VFA concentration was not affect, but ratio of acetate to propionate was linearly decreased (P<0.05),intake of N and flows of total N were increased (P<0.05) and microbial N efficiency was linearly (P<0.04) improved. With increasing Mon dosage from28to48mg/kg in diets,dry matter intake (DMI) was reduced (P<0.05), flow of OM to duodenum was decreased (P<0.01), ruminal digestibility of OM was increased (P<0.05), the total digestibility of OM was not affected, molar proportion of acetate and NH3-N concentration were increased (P<0.05). With increasing com DDGS inclusion in diets, intakes of total and individual fatty acid were linearly increased (P<0.01), flows (g/d) of CLA c9,t11, C18:3c9,c12,c15, monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) to the duodenum were linearly increased (P<0.01) However, intakes of total and individual FA tended (P<0.10) to be decreased, the flows of C18:2c9,c12, C18:3c9,c12,c15, MUFA and PUFA were decreased (P<0.05) with increasing Mon dosage in diets.Two hundred crossbred steers were assigned to5treatments with2×2+1factorial arrangement to determine the effects of increasing monensin supplementation and varying in wheat type on growth performance, carcass trait and composition of fatty acid in carcass of feedlot steers. The results showed that:DMI was not different between barley and wheat or between soft and hard wheat diets. However, increasing Mon reduced (P<0.01) DMI by6%. Final BW, average daily gain (ADG) and gain:feed intake (G:F) were not different between treatments. Carcass characteristics were generally not affected by treatments except that dressing percentage was slightly greater (P<0.05) for barley than for wheat diet. Additionally, steers fed soft wheat had less (P<0.05) back fat and greater (P<0.05) meat yield compared with hard wheat diet. Substitution of wheat for barley grain did not affect the total MUFA and PUFA, but decreased (P<0.05) C18:1t11and C18:3c9,c12,c15in the pars costalis diaphragmatic (PCD) muscles from beef cattle.These results indicate that increasing DDGS in finishing diet increases energy and protein availability and increases the provision of PUFA to feedlot cattle due to increased intake and flows of PUFA to the duodenum. Wheat can effectively replace barley grain in finishing ration without negatively influencing growth performance, carcass traits and fatty acid composition in meat. Feeding Mon at48vs.28mg/kg DM potentially improves feed efficiency and decreases intake and duodenal flows of FA as a result of reduced DMI, but had little effect on ruminal fermentation and had limit benefits to production efficiency even though DMI was reduced. |
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