Rebecca S. Stokes

Assessment of algae meal as a ruminant feedstuff: Nutrient digestibility in sheep as a model species.

Heterotrophic microalgae combined with soyhulls forms an algae meal (ALG), which contains partially deoiled microalgae (PDM; 57% DM basis) and soyhulls (43%). Two experiments were conducted to evaluate the effects of PDM and ALG on lamb digestibility. In Exp. 1, 8 wethers (23.02 ± 0.54 kg) were used in a 4 × 4 Latin square design to determine the effect of the PDM portion of ALG on total tract nutrient digestibility. Diets included a soyhull-based control (CON; 53% soyhulls), 10% PDM from ALG, 20% PDM from ALG (PDM20), and 30% PDM from ALG. Dry matter and OM intake and fecal DM and OM output were similar ( ≥ 0.11) between CON- and ALG-fed lambs. Urine output linearly increased ( = 0.02) as PDM increased in diets. Dry matter, OM, NDF, and ADF digestibility linearly decreased ( < 0.01) as PDM increased in diets. Ether extract digestibility did not differ ( = 0.24) between CON- and PDM-fed lambs. Nitrogen digestibility and N retention linearly decreased ( ≤ 0.05) as PDM increased in the diet. In Exp. 2, to determine the effects of ALG on diet and nutrient digestibility and N retention, 10 whiteface cross wethers (33.71 ± 0.55 kg) were used in a replicated 5 × 5 Latin square. Diets included a cracked corn-based control (CORN), 15% ALG, 30% ALG, 45% ALG (ALG45), and 60% ALG (ALG60). Dry matter and OM digestibility linearly ( < 0.001) decreased as ALG inclusion increased. Digestibility of NDF and ADF were lesser ( ≤ 0.03) for CORN-fed sheep than for ALG-fed sheep and linearly ( ≤ 0.03) increased as ALG increased in the diet. Ether extract digestibility was lesser ( = 0.002) for CORN than ALG, with a linear ( = 0.002) increase as ALG inclusion increased. There was a cubic ( = 0.03) effect for N digestibility with ALG45 and ALG60 being lesser and CORN being greater than all other treatments. Retention of N and plasma urea N concentration did not differ ( ≥ 0.22) between CORN and ALG. Nonfibrous carbohydrate digestibility linearly ( < 0.001) decreased as ALG increased in the diet. These results suggest that the PDM portion of ALG may be less digestible than soyhulls in ruminants, and differences in N retention in Exp. 1 may suggest an effect on growth in lambs. Furthermore, changes in digestibility of specific nutrients suggest that ALG is more characteristic of a concentrate rather than a fibrous feedstuff. However, lambs will readily consume ALG and this novel feedstuff could potentially serve as a viable component of ruminant diets.

Effects of increased inclusion of algae meal on finishing steer performance and carcass characteristics.

The deoiled residue from the production of heterotrophic microalgae can be combined with soyhulls to form a novel feedstuff called algae meal (ALG). To determine the effects of replacing corn in a finishing diet with ALG on growth, mineral status, carcass characteristics, and longissimus thoracis fatty acid profile, crossbred steers (168) were blocked by BW (432 ± 30.8 kg) into pens of 6 steers (7 pens per treatment). Pens received 1 of 4 diets: a corn-based control (CON), 14% ALG, 28% ALG (ALG28), and 42% ALG (ALG42). Corn was replaced by ALG on a DM basis. Steer BW were taken on d 0, 1, 28, 56, 74, 101, and 102, and steers were harvested on d 103. Pen was the experimental unit and DMI, ADG, and G:F data were analyzed as repeated measures. Two steers per pen were selected for sampling of blood and liver (d -1 and 96) and collection of rib steaks at harvest. There was a treatment by × time effect ( = 0.10) for overall DMI, where DMI linearly increased ( ≤ 0.008) across all time periods except Day 28 through, 56 when DMI was not different between ALG28 and ALG42. There was a treatment by time effect for ADG ( < 0.01), with ADG linearly decreasing ( ≤ 0.03) in the first and third month, not differing ( = 0.95) in the second month, and linearly increasing ( < 0.01) in the fourth month as ALG increased in the diet. Final BW and HCW did not differ ( ≥ 0.50) between CON- and ALG-fed cattle. There was a treatment × time effect for G:F ( < 0.01), with G:F linearly decreasing ( ≤ 0.01) in the first 3 mo as ALG increased in the diet, whereas G:F linearly increased ( < 0.01) in the fourth month. Based on steer performance, calculated dietary NEg linearly decreased ( < 0.01) as ALG increased in the diet. Yield grade linearly decreased ( = 0.02) and there was a tendency for dressing percent and 12th-rib back fat to linearly decrease ( ≤ 0.10) as ALG increased in the diet. Plasma Cu, Fe, and Mg concentrations were not different ( ≥ 0.31) in CON vs. ALG cattle; however, plasma Zn concentrations linearly increased ( = 0.03) as ALG increased in the diet. Total lipid, SFA, MUFA, and PUFA concentrations in the longissimus thoracis did not differ ( ≥ 0.13) between CON- and ALG-fed cattle. Interestingly, the atherogenic index linearly decreased ( < 0.01) as ALG increased in the diet. Algae meal may have a lesser energy value than corn; however, a minimal effect on carcass performance suggests ALG may serve as a potential replacement for corn in feedlot diets.

Effects of a Saccharomyces cerevisiae fermentation product in receiving diets of newly weaned beef steers. I. Growth performance and antioxidant defense1

To evaluate the effects of a Saccharomyces cerevisiae fermentation product (SCFP; Original XPC, Diamond V, Cedar Rapids, IA) on growth performance and antioxidant defense of newly weaned beef cattle, 180 single-source steers (278 ± 21 kg; SD) were used in a 56-d receiving study. Seven days after arrival, steers were blocked by body weight (BW) to pens of six and randomly assigned to treatments: SCFP at 0 (CON), 14 (SCFP14), or 28 (SCFP28) g·steer-1·d-1. Pen was the experimental unit (n = 10 per treatment). On d 0 steers were boostered against Bovine Viral Diarrhea Virus (BVDV) Type 1 and 2 (Vista Once, Merck, Madison, NJ). Weights were collected on d -1, 0, 14, 27, 42, 55, and 56. One steer per pen was bled on d 0, 14, 27, 42, and 56 for analysis of BVDV antibody titers; blood from d 0, 27, and 56 was analyzed for red blood cell lysate superoxide dismutase (SOD) activity and glutathione (total = tGSH, oxidized = GSSG, and reduced = GSH) concentrations, plasma malondialdehyde (MDA) concentrations, and serum lysozyme activity. Performance and blood data were analyzed as a randomized complete block design using Proc Mixed of SAS with fixed effects of treatment and block and random effect of pen. Linear and quadratic contrast statements were used. Antibody titers were log transformed and analyzed as repeated measures. There were no treatment by day interactions (P ≥ 0.16), and no linear or quadratic effects of SCFP on feedlot performance, antibody titers, or lysozyme activity (P > 0.10). Day 27 MDA concentrations tended to linearly increase (P = 0.09). A quadratic effect of SCFP on d 56 SOD activity (P = 0.004) was driven by lesser activity for SCFP14-fed steers. On d 27 a tendency for a quadratic effect of SCFP (P = 0.09) on GSH was driven by greater concentrations for SCFP14-fed steers resulting in a lesser GSSG:GSH ratio (P = 0.05). Greater GSH for SCFP14-fed steers caused a tendency for a quadratic effect on d 56 (P = 0.07); however, this did not result in an effect of SCFP on the GSSG:GSH ratio (P ≥ 0.25). A tendency for a linear effect of SCFP on tGSH was noted on d 56 (P = 0.09). Morbidity data were analyzed using Proc Glimmix of SAS. There was a quadratic effect of SCFP on percentage of respiratory treatments prior to d 14 (P = 0.04). These results could indicate lesser levels of oxidative stress for steers receiving SCFP at 14 g/d vs. 0 or 28 g/d. Under the conditions of this study no performance benefit of SCFP was noted.

Effects of a Saccharomyces cerevisiae fermentation product in receiving diets of newly weaned beef steers. II. Digestibility and response to a vaccination challenge

Thirty-six newly weaned, crossbred beef steers (323 ± 12 kg; SD) from a single-source were used in a 56-d study to examine the effects of a Saccharomyces cerevisiae fermentation product (SCFP; Original XPC, Diamond V, Cedar Rapids, IA) on total tract nutrient digestibility and response to a vaccination challenge. Twelve d after arrival, steers were blocked by body weight (BW) and randomly assigned to treatments: SCFP at 0 (CON), 14 (SCFP14), or 28 (SCFP28) g·steer-1·d-1. Steers were fed via bunks that measured individual intake and received ear tags (CowManager, Select Sires, Plain City, OH) that recorded rumination and activity. Body weights were collected on d -1, 0, 14, 28, 42, 55, and 56. Titanium dioxide was fed as an indigestible marker to all steers from d 12 to 27, followed by consecutive d fecal samples, for determination of total tract nutrient digestibility. On d 34, steers received a Mannheimia haemolytica vaccination (One Shot, Zoetis, Kalamazoo, MI) to induce an acute phase protein (APP) response. Blood was collected from all steers on d 34 (prior to vaccination) and 3, 6, 9, 11, and 14 d post-vaccination. Data were analyzed using Proc Mixed of SAS (experimental unit = steer; n = 12/treatment); the model included the fixed effect of treatment and block and the random effect of steer. Blood measures, ear tag, and dry matter intake (DMI) data for the 15-d vaccination period were analyzed as repeated measures. Contrast statements (CON vs. SCFP14; SCFP14 vs. SCFP28) were used to compare treatment means. Digestibility of dry matter and organic matter was greater for SCFP14 vs. SCFP28 (P ≤ 0.03). Steers fed SCFP14 exhibited greater crude protein digestibility compared to CON (P < 0.01). Steers fed SCFP14 exhibited greater DMI for 15 d post-vaccination (P = 0.02) and greater ADG from d 28 to 56 (P = 0.05) vs. SCFP28-fed steers. Post-vaccination, steers fed SCFP14 spent less time ruminating per kg of dry matter, neutral detergent fiber (NDF), and physically effective NDF consumed than CON or SCFP28 (P ≤ 0.07). Serum IL-8 and haptoglobin concentrations tended to be lesser for steers fed SCFP14 vs. SCFP28 (P ≤ 0.08). Ceruloplasmin concentrations were lesser on d 14 post-vaccination for steers fed SCFP14 vs. CON or SCFP28 (treatment × d; P = 0.004); there were no differences on other sampling days due to treatment. Although no overall performance benefit was noted, steers fed SCFP14 responded better to a vaccination challenge vs. SCFP28-fed steers.

Effects of Increased Inclusion of Algae Meal on Lamb Total Tract Digestibility

and Implications Algae meal is a novel coproduct created by the unique combination of soybean hulls and oil-extracted heterotrophic micro algae. Algae meal is highly digestible by ruminants and was readily consumed by lambs when included at up to 60% of the diet dry matter. This suggests that algae meal could potentially replace corn or soybean hulls and serve as a valuable component of feedlot diets. Introduction Recently a new coproduct has become available from the large scale commercial production of heterotrophic microalgae utilized for bioenergy and oil. This coproduct, when combined with soyhulls, offers a unique combination of fiber, protein, and fat and may play a role as an alternative feedstuff in animal diets. The ruminant animal, with their unique capability to convert what would otherwise be waste products into nutritious animal protein via fermentation, serves as the ideal model for analyzing this coproduct. Naturally produced microalgae has been previously studied however, concentrations of Na, Fe, Cu, and Al, ultimately limited inclusion in diets because of potential for toxicity of micro-and macro minerals. The algae used in the current study is produced by a heterotrophic fermentation process and grown in dark fermenters, and the resulting algae meal is not limited by excess micronutrients. Previous research showed that beef cattle will readily consume algae meal at concentrations less than 45% diet DM. The nutrient composition of algae meal suggests that this feedstuff may serve as a valuable replacement for soyhulls or perhaps corn. Therefore the objective of this study was to determine the impact of replacing corn with increasing inclusions of algae meal on total tract nutrient digestibility in sheep.