Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2009
Publication Date: 8/20/2009
Citation: Spiehs, M.J., Varel, V.H. 2009. Nutrient Excretion and Odorant Production in Manure from Cattle Fed Corn Wet Distillers Grains With Solubles. Journal of Animal Science 87:2977-2984. Online. Journal of Animal Science doi:10.2527/jas.2008-1584.
Interpretive Summary: Distiller’s grains are a feed ingredient used in cattle feedlot diets. Waste from cattle fed distiller’s grains may contain more odorous compounds than waste from cattle fed corn-based diets. The waste may also contain high levels of nutrients such as nitrogen and phosphorus which are potentially detrimental to the environment. This study evaluated the effects of distiller’s grains on odor and nutrients in waste from feedlot cattle.
Technical Abstract: Twenty-four cross bred steers (BW 452. 5 ± 15.5 kg) were used to evaluate nutrient excretion and odorous compounds in urine and feces of feedlot steers fed diets containing corn wet distillers grains with solubles (WDGS). Cattle were weighed, blocked by weight, and assigned randomly to one of four dry-rolled corn-based diets containing 0, 20, 40, or 60% WDGS (DM basis). A 96-h total fecal and urine collection was conducted. Orts, feces, and urine were collected daily. Samples were analyzed for moisture, total N, total P, water soluble P, and total S. Fresh fecal samples were collected at the end of the balance trial for analysis of VFA, phenol, p-cresol, indole, skatole, ammonia-N, and lactate concentration. Total P, N, and S intake increased linearly as the level of WDGS increased in the diet (P < 0.02). Total P excretion increased linearly as the level of WDGS increased in the diet (15, 19, 21, and 25 g/d, respectively for the 0, 20, 40, and 60% diets; P < 0.01). There was a tendency for greater water soluble P excretion in feces from cattle fed the 60% WDGS compared to cattle fed the 0% WDGS diet (1.6 vs. 0.9 g/d, respectively; P = 0.06). Total N excretion increased linearly as dietary WDGS inclusion increased and was greater (P < 0.01) for cattle fed the 60% WDGS diet (174.6 g/d) than for cattle fed the 0 and 20% WDGS diets (110.2 and 120.9 g/d, respectively). Total S excretion was greater (P < 0.01) for cattle fed the 40% WDGS diet (18.7 g/d) than cattle fed the 0 or 20% WDGS diet (8.3 and 14.1 g/d, respectively). Dietary treatment did not affect the concentration of odorous compounds in urine. Total VFA concentration in feces was greater for cattle fed the 0 and 20% WDGS diets than for cattle fed the 40 and 60% WDGS diets, but branched-chained VFA concentrations (isobutyrate and isovalerate) in feces were higher for cattle fed the 60% WDGS diet than for cattle fed the other three dietary treatments. There was no difference in the concentration of aromatic compounds (phenol, cresol, indole, skatole) in feces from cattle fed the four dietary treatments. Cattle fed the 0% WDGS diet had lower (P < 0.01) ammonia-N concentration in feces (10.2 mg/g DM) compared to cattle fed the 40 and 60% WDGS diets (21 and 27 mg/g DM, respectively). This study indicates that feeding greater than 40% WDGS to feedlot cattle increases N, P, and S excretion and may increase odorants in feces of feedlot cattle.