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1528
Effects of field pea supplementation on digestibility and rumen VFA concentration of diets containing high and low quality forages
Five ruminally fistulated steers (Initial BW = 202 kg; SD = 20 kg) were utilized in a 5 × 6 Latin rectangle to evaluate the effects of supplementation on total tract digestibility of diets containing either high or low quality forages. Treatments were set up as a 2 × 3 factorial (forage quality × supplement type). The first factor was high quality forage (HQ; 50% alfalfa, 50% sorghum silage, DM basis) or low quality forage (LQ; 50% brome grass hay, 50% wheat straw, DM basis). The second factor was one of three supplements: Control (CON), Dry-rolled Corn (DRC), or Field Peas (FP). Steers were supplemented at 0.43% of BW (DM basis). Periods lasted 14 days with a 9 day adaptation period and 4 day collection period. Data were analyzed using the mixed procedure of SAS and evaluating significance at α = 0.05. There were no interactions between forage quality and supplement type on digestibility (P ≥ 0.25). Dry matter intake, DM digestibility (DMD), OM intake (OMI), and OM digestibility (OMD; P < 0.01) were greater with HQ forage (6.13 kg/d, 63.1%, 4.96 kg/d, and 64.2%, respectively) than diets containing LQ (4.71 kg/d, 49.1%, 3.60 kg/d, and 50.1%, respectively). The FP supplement (P ≤ 0.03) increased DMI and OMD (6.14 ± 0.512 kg/d and 61.6% ± 1.94%, respectively) over steers receiving DRC (5.33 kg/d and 56.1%, respectively) or CON (4.80 kg/d and 53.8%, respectively), DRC and CON did not differ in intake or OMD. The acetate to propionate ratio (A:P) was affected by both forage and supplement where HQ was less than LQ (3.61 ± 0.05 and 4.09 ± 0.05, respectively) and DRC supplement produced lower A:P (3.58 ± 0.07) than FP and CON (3.99 and 3.97 ± 0.07, respectively) which were similar. Propionate proportions differed with HQ tending (P = 0.06) to have greater concentrations than LQ. There was a supplement effect (P = 0.01) where DRC increased propionate proportion over CON and FP (18.88%, 17.96%, and 17.72 ± 0.27%, respectively). Acetate proportions (P < 0.01) were greater for the LQ forage (72.3 ± 0.58%) than HQ forage diet (64.8 ± 0.58%). A supplement effect was observed for acetate (P < 0.01) with CON and FP values greater than DRC. Supplementing FP in low or high quality diets increases DMI and OMD and may be an acceptable supplement for beef cattle.
Keywords: cattle, field peas, forage quality