Effect of post-ethanol extraction sorghum silage as a forage source in growing and finishing diets on steer performance, carcass characteristics, and nutrient digestibility.

Two experiments evaluated the use of post-ethanol extraction sorghum silage as an alternative forage source in feedlot diets. Seventy-two crossbred steers (397 kg [SD 23]) were used to evaluate growth and carcass characteristics. Steers were blocked by BW into pens of 6 steers and randomly assigned to growing diets containing 40% (DM basis) sorghum silage (SS; 57.6% NDF) or grass hay (CON; 63.3% NDF) for 56 d ( = 6 pens per treatment). Within each treatment, steers transitioned to dry-rolled corn-based finishing diets (fed for 56 d) containing 6% effective NDF contributed by the forage source, resulting in forage inclusions of 16% for SS and 13.1% for CON, where forage replaced corn. A subsample of steers ( = 12 per treatment) housed in pens equipped with GrowSafe bunks were used for determination of growing phase diet total tract digestibility. From d 28 to 42, steers received titanium dioxide at approximately 10 g∙steer∙d, and fecal samples were collected on d 41 and 42. Fecal and total mixed ration samples were dried and ground for analysis of DM, OM, NDF, ADF, CP, ether extract (EE), and starch. Data were analyzed with the MIXED procedure of SAS, with fixed effects of treatment and block for performance and carcass data or treatment for digestibility data; significance was determined at ≤ 0.05 and tendencies at ≤ 0.10. Growing phase DMI and ADG did not differ due to treatment ( ≥ 0.19); however, SS-fed steers had improved G:F compared with CON-fed steers ( = 0.04). Finishing period ADG and G:F did not differ ( ≥ 0.15) between treatments, despite SS-fed steers having lesser ( = 0.008) DMI than CON-fed steers. No differences in DMI, ADG, or G:F over the whole trial were noted between treatments ( ≥ 0.12) nor were any carcass traits affected ( ≥ 0.23). During the digestibility assessment period, DMI was less ( = 0.003) in SS-fed steers. Growing phase total tract apparent digestibility of DM and starch did not differ ( ≥ 0.19) due to treatment; however, OM digestibility tended to be greater ( = 0.09) in SS-fed steers. Steers fed SS had greater ( ≤ 0.03) digestibility of EE, CP, NDF, and hemicellulose than CON-fed steers. However, CON-fed steers had greater ( < 0.0001) ADF digestibility than SS-fed steers. These data suggest that postextraction sorghum silage can be effectively used in feedlot diets as an alternative forage source.

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.

Determining the preference, in vitro digestibility, in situ disappearance, and grower period performance of steers fed a novel algae meal derived from heterotrophic microalgae.

A series of 3 experiments were conducted to determine the in vitro and in situ disappearance, preference, and performance of steers consuming increasing concentrations of a novel feedstuff called algae meal (ALG). In Exp. 1 and 2, 3 ruminally cannulated steers (998 ± 103 kg BW) and 4 treatments were utilized: a dry-rolled corn-based diet (CON), or 15% ALG (A15), 30% ALG (A30), or 45% ALG (A45) as a DM replacement of corn. Experiment 1 was performed as a 3 × 6 unbalanced Latin square with six 5-d periods, and 6 paired diet combinations to determine steer preference, based on DMI for 4 h after feed delivery. Experiment 2 was conducted as a 3 × 4 unbalanced Latin square with 3 diets fed each period and four 14-d periods to determine in situ disappearance of ALG, soyhulls, corn, and hay as ALG increased in the diet. Experiment 3 utilized 48 individually fed steers (292 ± 22.4 kg; n = 12) in a 55-d grower trial, stratified by BW into 1 of 4 dietary treatments: a control wet corn gluten feed-based diet with no ALG (ALG0), or 15% ALG (ALG15), 30% ALG (ALG30), or 45% ALG (ALG45) in place of wet corn gluten feed on a DM basis. Digestibility of ALG was greater (P < 0.001) than soyhulls at 24 h, but was similar (P = 0.82) at 48 h, with hay being least (P < 0.001) digestible at 24 and 48 h. In Exp. 1, the proportion of total DM consumed by steers during the 4-h postfeeding was affected (P = 0.01) by paired diet combination. Steers preferred A15 or A30 diets over the A45 diet (P ≤ 0.008); however, no difference in preference between CON and A45 was noted (P = 0.76). Steers tended (P = 0.09) to prefer A30 over CON, but A15 and CON were not different (P = 0.75). No other paired diet combinations altered (P ≥ 0.23) DMI. In Exp. 2, inclusion of ALG in the diet did not affect (P ≥ 0.12) rate of, or overall in situ disappearance of, corn, soyhulls, or ALG. In Exp. 3, ADG tended ( = 0.06) to increase as ALG increased in the diet. There was a linear increase ( < 0.001) in DMI as ALG increased in the diet, and as a result, G:F linearly decreased ( = 0.01). In summary, ready consumption of the novel algae meal by steers and support of growth in steers at up to 45% of the diet suggest the algae meal is a viable feedstuff for ruminants.

Influence of distillers grains resulting from a cellulosic ethanol process utilizing corn kernel fiber on nutrient digestibility of lambs and steer feedlot performance.

Two experiments evaluated the effects on animal performance of traditional wet distillers grains (T-WDG) compared to cellulosic wet distillers grains (C-WDG) from a new process converting corn kernel fiber into cellulosic ethanol. The resulting coproduct has greater CP and decreased starch and ether extract (EE) concentrations (34.0% CP, 1.6% starch, 7.3% EE) compared to T-WDG (32.5% CP, 5.1% starch, 7.7% EE). In Exp. 1, 10 wethers (34.1 ± 2.35 kg, SD) were used in a replicated 5 × 5 Latin square to evaluate digestibility of DM, fiber, EE, and N. Diets including a corn-based control with 7.5% T-WDG and 7.5% C-WDG (CORN); 30% or 45% inclusion of T-WDG; and 30% or 45% inclusion of C-WDG. Between CORN, 30% T-WDG, 45% T-WDG, or 45% C-WDG, DMI was not different (P ≥ 0.11), but lambs fed 30% C-WDG had decreased (P ≤ 0.05) DMI compared to other diets. Compared to CORN and 30% T-WDG, DM digestibility was lesser ( P< 0.05) for 45% T-WDG or 30% C-WDG, while 45% C-WDG has lesser (P ≤ 0.05) DM digestibility than all other treatments. Digestibility of NDF was not affected by treatment (P= 0.13), and ADF digestibility was not different ( 0.21) between CORN, 30% T-WDG, 30% C-WDG, or 45% C-WDG. However, digestibility of ADF tended to differ (P = 0.06) between 30% T-WDG and 45% C-WDG and was greater (P ≤ 0.05) in lambs fed 45% T-WDG compared to other treatments. In Exp. 2, 168 steers (421 ± 23.9 kg, SD) were used in a randomized complete block design to determine the impact of C-WDG or T-WDG on growth performance and carcass characteristics. Diets included a corn-based control (CON), 30% T-WDG (TRAD), 30% C-WDG (CEL), and 18% C-WDG and 12% condensed corn distillers solubles (CEL+CCDS; = 7 pens of 6 steers/pen). Steers fed TRAD had improved (P ≤ 0.01) ADG, G:F, and HCW compared to steers fed the CON diet. No differences (P ≥ 0.16) in ADG and HCW were noted for steers fed CEL compared to TRAD; however, steers fed CEL had decreased (P = 0.01) G:F due to increased (P = 0.02) DMI compared to TRAD-fed steers. Steers fed CEL or CEL+CCDS did not differ (P = 0.50) in G:F, but CEL+CCDS-fed steers had lesser (P ≤ 0.01) DMI and ADG likely due to greater S content of the CEL+CCDS diet. Overall, while DM digestibility of lambs fed 30% C-WDG was lesser than 30% T-WDG, performance of steers finished on C-WDG was similar to those fed T-WDG. However, WDG from the secondary fermentation appeared to have lesser energy than T-WDG, while maintaining similar cattle performance to corn-fed controls.

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.

Hormone secretory patterns, pituitary characteristics and selected blood metabolites in feedlot steers implanted with growth stimulants.

Twelve Charolais-crossbred steers (256 kg) received one of three treatments: nonimplanted controls (C), implanted initially and at 84 days with 36 mg zeranol (Ralgro, R) and implanted initially and at 84 days with 200 mg of progesterone and 20 mg of estradiol benzoate (Synovex-S,S). All steers were fed a corn-based diet (calculated metabolizable energy 2.89 Mcal/kg dry matter) ad libitum. In a parallel comparative slaughter trial, rates of empty body protein accretion were increased 14% in R and 24% in S steers (P less than .01). R and S steers in the present study had heavier pituitary weights (P less than .001), more pituitary growth hormone content (P less than .04) and more pituitary weight/unit live weight (P less than .05) than did C steers. Cattle implanted with R or S exhibited an increased growth hormone (GH) secretory response to a pituitary challenge with thyrotropin releasing hormone (TRH). Plasma insulin profiles were not significantly altered, but tended to be greater for steers given implants. Overall 9-hr GH secretory profiles were not affected by implantation. Plasma urea N at 94 days post-implantation was decreased (P less than .01) by implantation. Plasma glucose was increased (P less than .04) at both 94 and 199 days in R and S vs C steers. Overall mean and total (integrated area) plasma GH, as well as secretory profile components (baseline mean, amplitude of secretory spikes) were negatively correlated with body weight and size on days 94 and 199. Overall mean, baseline and integrated area of plasma insulin on days 94 and 199 were positively related to body weight and size. Thus positive protein anabolic growth responses from implantation (parallel comparative slaughter trial) were coupled with increased pituitary GH content and little change in circulating plasma GH concentrations between implanted and control steers. This may suggest that changes in tissue sensitivity, an increased plasma clearance rate of GH and/or a direct effect on target tissues may be involved in the improved growth performance of cattle implanted with R or S.

Optimal beef cattle diets formulated by nonlinear programming.

A beef diet model based on National Research Council recommendations is significantly nonlinear for feed ingredients, daily gain and weight of cattle. Solving a diet model has been difficult, but advances in nonlinear programming now allow solutions that are quick and easy. This study developed a nonlinear programming method for optimally planning a feeding program by choosing feeds, daily gains and selling weight. Two types of diets are important for this purpose:optimal-return diets and least-cost-gain diets. For a given weight of cattle, an optimal-return diet chooses feeds and daily gain to maximize returns above feed costs. A least-cost-gain diet chooses feeds and daily gain to minimize feed plus yardage costs per kilogram of gain. In an optimal feeding program, a sequence of optimal-return diets is fed to increasing weights of cattle. Feed costs plus yardage per kilogram of gain rise to equal the actual selling price at the optimal selling weight, and the cattle are sold. Cattle feeders and researchers with access to a microcomputer can maximize net returns from a feeding program.

Rate, composition and efficiency of growth in feedlot steers reimplanted with growth stimulants.

Eighty Charolais-cross steer calves (283 kg) were fed a moderately high-energy (2.89 Mcal ME/kg) diet for 189 d to examine the effects of reimplantation of 36 mg of zeranol (Ralgro) or 200 mg progesterone plus 20 mg estradiol benzoate (Synovex-S) on the rate, composition and efficiency of gain, skeletal size and carcass parameters in a comparative slaughter trial. The implant treatments included unimplanted controls (C), Ralgro initially (R1), Synovex-S initially (S1), Ralgro initially and a reimplant at 84 d (R2) and Synovex-S initially and a reimplant at 84 d (S2). Both implants increased (P less than .06) gains by 8.1% from 0 to 84 d. Ralgro and Synovex-S increased (P less than .01) daily gains by 11.5% and 25.2%, respectively, from 84 to 189 d. The duration of the response to a single implant appeared to be in excess of 140 d; thus, reimplantation did not further increase daily gains. Reimplantation did improve (P less than .05) feed utilization in Ralgro implanted steers, however. Ralgro and Synovex-S increased (P less than .01) the rate of empty body (EB) protein accretion by 14.1% and 24%, respectively, without affecting EB fat growth. The efficiency of protein gain per unit protein (P less than .05) or energy intake (P less than .04) was improved, but the efficiency of energy gain per unit energy intake was not affected by implantation. Carcass weights of implanted steers were 5% greater (P less than .04) when adjusted to an equal carcass fatness. Both growth stimulants increased hip height (P less than .02), wither height (P less than .08) and body length (P less than .08) over C steers at slaughter.