PSXII-33 Effects of quality and inclusion rate of roughages on feed intake growth rumen fermentation characteristics and blood parameters of growing Hanwoo steers (Bos taurus coreanae).

摘要

Finding ways to reduce roughage feeding without negatively affecting rumen health has been of interest in ruminant nutrition. The present study aimed to investigate the effects of quality and content of roughage on growth performance, ruminal fermentation, and blood metabolite levels in growing steers. Twenty-four Hanwoo steers (224 ± 24.7 kg) participated in this 24-week trial. The animals were fed TMR. Two types of concentrate mixes [high spec (HS) and low spec (LS)] were prepared to formulate iso-nitrous and iso-caloric TMR. The treatments were arranged as a 2 x 2 factorial with treatments consisting of 32% timothy and 68% HS (THS), 24% timothy with 76% LS (TLS), 24% ryegrass with 76% HS (RHS), and 17% ryegrass with 83% LS (RLS). Individual feed intakes were recorded using an automated system. Rumen fluid and blood before morning feeding were sampled and BW was measured every four weeks. Rumen fluid was collected using a stomach tube for five consecutive days at different sampling times each day (0800, 1100, 1300, 1500, and 1700). Mean DMI (7.33 kg) and ADG (1,033 g) did not differ among treatments. However, interactions between forage type and concentrate mix were observed in rumen and blood parameters (P < 0.05). Total VFA concentration was higher (P < 0.05) in TLS-fed steers than in the others. When timothy was provided, lower inclusion of roughage decreased propionate, increased butyrate, and increased acetate:propionate ratio. The opposite trends were observed when ryegrass was the source of roughage. In addition, the concentrations of plasma total protein, alanine transaminase, Ca, inorganic P, total cholesterol, triglycerides, and creatine were affected by treatments (P < 0.05). We concluded that rumen fermentation and body metabolism of the growing steers were affected by the quality and inclusion level of roughage in the diet, even though growth performance was unaffected.