Feeding Red Osier Dogwood (Cornus sericea) Affected Feed Intake and Digestion in the Digestive Tract of Beef Heifers Fed High-Grain Diet

Red osier dogwood (ROD; Cornus sericea) is an abundant native shrub plant across Canada and it is rich in bioactive compounds with total phenolic concentration varying between 40 to 220 mg/g depending on the season. The phenolics include anthocyanins, gallic acid, ellagic acid, quercetin, and cyanin have both antioxidant and antimicrobial properties. Studies demonstrated that feeding ROD may reduce the use of antibiotics in livestock animals. It is hypothesized a greater feed value than barley silage in beef cattle diet. The objective was to determine the effect of increasing substitution of ROD for barley silage in high-grain diet on ruminal pH and fermentation, feed digestion in the total digestive tract in beef heifers. Five rumen cannulated Angus heifers (BW = 660 ± 40.8 kg) were used in a 5 × 5 Latin square design. Treatments were control diet containing 15% barley silage and 85% barley concentrate (DM basis), diet that substituted with 3%, 7% or 15% of ROD for equal barley silage, or diet supplemented with monensin (28 mg/kg diet DM). Ruminal pH was monitored continuously for 4 days using wireless pH probe of each period. Fermentation characteristics were measured for two consecutive days at 1, 3, 5, and 7 h of each day after the morning feeding. Apparent digestibility was determined using Cr₂O₃ as external marker by sampling feces from the rectum. Data were analysed using the MIXED procedure of SAS with model including fixed effect of diets and random effects of heifer and period. Intake of DM quadratically (P<0.02) increased with increasing the replacement of silage by ROD from 0, 3, 7 to 10% (11.5, 12.1, 12.4 and 11.8 kg/d). Mean ruminal pH ranged from 5.95 to 6.14 and were not affected by diets, and no effects of diets on total VFA concentration (averaged 138 mM) were observed. However, ruminal NH₃-N concentration linearly (P < 0.01) decreased with increasing ROD (10.7, 9.0, 9.8 and 8.0 mM). Digestibility of DM quadratically (P<0.01) increased with increasing ROD from 0, 3, 7 to 10% (72.9, 74.8, 77.2 and 75.0%). Furthermore, feeding ROD vs. monensin increased DM intake (12.1 vs. 11.2 kg/d; P<0.01), DM digestibility (75.8 vs. 72.1%; P<0.01), and VFA concentration (141 vs. 130 mM; P<0.05). These results indicate greater feed value of ROD vs. barley silage or monensin but it was dose-dependant. It suggests that ROD could be fed potentially as an alternative to silage or monensin in beef cattle.