Spirulina supplementation during the transition period by grazing dairy cattle at tropical highland conditions.

The objective of this experiment was to evaluate the effects of spirulina supplementation on oxidative stress, immunity, and productive performance during the transition period by grazing dairy cattle. Thirty multiparous gestating cows with an initial body weight (BW = 544 ± 57 kg) were enrolled in this experiment and were stratified by expected calving date. Cows were randomly assigned to one of the three experimental groups: (1) control, no supplementation of spirulina; (2) spirulina-15 (15 g/day of spirulina); and (3) spirulina-30 (30 g/day of spirulina). Body weight and body condition score (BCS) were recorded and blood samples were collected at - 21, 1, and 14 days, relative to calving. The day of parturition, colostrum and blood samples from calves were collected to measure IgG concentrations. After parturition milk yield, milk components and somatic cell count were monitored. Body weight, BW loss, BCS, and total antioxidant capacity were not affected by spirulina supplementation (P > 0.23) at any time point measured. Milk yield, milk components, and somatic cell count were not altered by treatment (P > 0.13). Results from this experiment suggest neither positive nor negative effects of spirulina supplementation on oxidative stress and productive performance during the transition period.

Effects of wet corn distillers grains with solubles on visceral organ mass, trace mineral status, and polioencephalomalacia biomarkers of individually-fed cattle.

Twenty-four steers (initial BW = 385 ± 1.1 kg) were blocked by BW and randomly assigned to 3 dietary treatments (0, 30, or 60% wet distillers grains with solubles [WDGS]; DM basis) and were fed individually to determine the effect of WDGS on live growth and carcass performance, visceral organ mass, trace mineral status, and polioencephalomalacia biomarkers. Steers were slaughtered at 125, 150, 164, and 192 d (2 blocks/slaughter date) when external fat depth was approximately 1.3 cm based on visual appraisal. Steers fed 30% WDGS had greater DMI than those fed 0 or 60% WDGS (P < 0.05), and steers fed 60% WDGS had the lowest carcass-adjusted ADG (P < 0.09) of the 3 treatments. Nonetheless, WDGS concentration did not alter feed efficiency (P > 0.41) on either live or carcass-adjusted basis. Steers fed 30% WDGS had greater liver S and Mn concentrations (DM basis) and lower liver Fe concentrations than control steers (P < 0.10; initial values used as a covariate), and feeding 60% WDGS decreased liver Cu and increased liver Fe (P < 0.10) compared with feeding 30% WDGS. Cytochrome c oxidase (COX) activity in brain tissue tended to be decreased with 60 vs. 30% WDGS (P = 0.12), and COX activity decreased linearly (P = 0.06) in lung tissue as dietary WDGS concentration increased. Likewise, gut fill linearly increased (P = 0.01) with increasing WDGS concentration. Feeding 30% WDGS increased fractional mass (g/kg of empty BW) of the small intestine (P < 0.10) compared with controls, whereas 60% WDGS increased fractional kidney mass (P < 0.10) compared with 30% WDGS. Overall, results suggest that gut fill, Cu status, and COX activity seem to be compromised by WDGS when fed at 60% of diet DM in diets based on steam-flaked corn, which suggests a greater susceptibility to polioencephalomalacia.

Effects of a dietary sweetener on growth performance and health of stressed beef calves and on diet digestibility and plasma and urinary metabolite concentrations of healthy calves.

Two experiments were conducted to explore the effects of a sodium saccharin-based dietary sweetener (Sucram) on growth performance, health, and physiological responses of feedlot steers. In Exp. 1, 173 newly-received male calves purchased from auction barns were fed 0, 100, 200, or 300 g of Sucram/t of DM over 56 d. Overall, ADG and G:F (P > 0.10) were not different among treatments, but steers receiving 200 g Sucram/t displayed numerically greater ADG (23%). In addition, DMI was 17% greater for steers receiving 200 g of Sucram/t compared to steers fed the control diet (cubic effect, P = 0.09). The morbidity rate for respiratory disease did not differ (P > 0.50) among treatments. In Exp. 2, 15 steers (initial BW = 261 ± 28 kg) were used to evaluate the effects of Sucram on apparent total tract digestibility, plasma metabolite concentrations, and urine monoamine metabolite concentrations. Treatments consisted of ad libitum access to a 60% concentrate diet (Control), ad libitum access to Control + 200 g of Sucram/t of DM (Adlib), and Control + 200 g of Sucram/t of DM with feed intake paired to the Control (Paired). By design, steer DMI during the metabolism period did not differ (P = 0.34) between Paired and Control, but DMI tended (P = 0.14) to be 8.2% greater for Adlib than for Control. Treatments did not alter (P > 0.17) apparent total tract nutrient digestibility. Postprandial plasma citrulline concentration was lower (P = 0.03) for Adlib than for Control and tended to be lower (P = 0.13) for Paired than for Control. Plasma homocysteine concentration was reduced (P < 0.03) by feeding Sucram. Urinary concentrations of ethylmalonic acid, vanillymandelic acid, and 5-hydroxyindolacetic acid were greater (P < 0.06) for Adlib than for Control; Paired steers had a greater (P = 0.02) urine vanillymandelic acid concentration than Control steers and tended (P < 0.12) to have a greater urinary concentration of ethylmalonic and 5-hydroxyindolacetic acid than Control steers. Serum insulin was greater for Adlib than for Control steers (P = 0.04) and tended to be greater for Paired than for Control steers (P = 0.14), but serum prolactin area did not differ (P > 0.22) among treatments. Supplementation with Sucram may increase feed intake by newly-received, stressed feedlot calves. Saccharin supplementation reduced plasma homocysteine and increased urinary excretion of vanillymandelic acid, suggesting an improved activity of the dopamine reward system.

Effects of bulk density of steam-flaked corn in diets containing wet corn gluten feed on feedlot cattle performance, carcass characteristics, apparent total tract digestibility, and ruminal fermentation.

The effects of varying bulk density of steam-flaked corn (SFC) in diets containing wet corn gluten feed (WCGF; Sweet Bran; Cargill Corn Milling, Blair, NE) have not been defined. In Exp. 1, yearling steers (n = 108; initial BW = 367 ± 1.18 kg) were housed in 27 pens (4 steers/pen) and received 1 of 3 different SFC bulk density treatments in a randomized complete block design. Bulk density treatments were 283, 335, or 386 g/L SFC in diets containing 25% WCGF (% of DM). Steers were fed once daily to provide ad libitum access to feed for an average of 163 d. For a 5-d period before d 70 of the experiment, DMI was measured, and fecal samples were collected from each pen for measurement of nutrient digestibility using dietary acid insoluble ash as a marker. Varying bulk densities of SFC did not affect (P ≥ 0.233) overall DMI, ADG, or G:F on a live- or carcass-adjusted basis. Dressing percent and LM area increased linearly (P ≤ 0.05) as bulk density increased, but other carcass traits were not affected by treatments. Intake of DM, OM, and CP during the 5-d digestion phase did not differ among bulk densities; however, starch intake increased linearly (P = 0.004) as bulk density of SFC increased. Digestibility of DM, OM, and CP tended (P ≤ 0.065) to decrease and starch digestibility decreased (P = 0.002) linearly as bulk density of SFC increased. In Exp. 2, a 3 × 3 Latin square design was used for collection of ruminal fluid from 3 ruminally cannulated Jersey steers adapted to the same diets used in Exp. 1. Bulk density did not affect NH3 concentrations, VFA molar proportions, ruminal fluid osmolality, and IVDMD of the diets. Total gas production increased linearly (P = 0.003) as bulk density of SFC increased from 283 to 335 g/L, but it decreased (P = 0.002) at 386 g/L. Present data suggest that bulk density can be increased up to 386 g/L in finishing diets containing 25% (DM basis) WCGF without affecting cattle performance and with limited effects on ruminal fermentation; however, digestibility of starch seemed to be affected negatively by increased bulk density in these diets.

Effects of dietary concentration of wet distillers grains on performance by newly received beef cattle, in vitro gas production and volatile fatty acid concentrations, and in vitro dry matter disappearance.

Three studies were designed to evaluate effects of wet distillers grains with solubles (WDGS) on health and performance of newly received beef cattle, in vitro gas production, molar proportions and total concentrations of VFA, and IVDMD. In Exp. 1 and 2, 219 (BW = 209 kg, SE = 2.2 kg; Exp. 1) and 200 beef steers (BW = 186 kg, SE = 3.2 kg; Exp. 2) were used in randomized complete block design receiving studies. The 4 dietary treatments (DM basis) were a 65% concentrate, steam-flaked corn (SFC)-based receiving diet without WDGS (CON) or diets that contained 12.5, 25.0, or 37.5% WDGS. There were no differences among the 4 receiving diets in BW (P ≥ 0.61), ADG (P ≥ 0.75), DMI (P ≥ 0.27), and G:F (P ≥ 0.35), or in the proportion of cattle treated for morbidity from bovine respiratory disease in either of the 2 experiments. In Exp. 3, in vitro methods were used to determine the effects of WDGS on IVDMD, total gas production, and molar proportions and total concentrations of VFA. Substrates used for the incubations contained the same major components as the diets used in Exp. 1, with ruminal fluid obtained from steers fed a 60% concentrate diet. Total gas production was less (P = 0.03) for the average of the 3 WDGS substrates than for CON, with a linear decrease (P = 0.01) in total gas production as WDGS concentration increased in the substrates. In contrast to gas production, IVDMD was greater for the average of the 3 WDGS concentrations vs. CON (P ≤ 0.05) at 6 and 12 h and increased (P ≤ 0.02) with increasing WDGS concentration at 6 (linear and quadratic) and 12 h (linear) of incubation. At 48 h, there was a quadratic effect (P = 0.05) on IVDMD, with the greatest value for 25% WDGS. Molar proportion of butyrate increased linearly (P < 0.01) as the concentration of WDGS increased in the substrate, and the average of the 3 substrates containing WDGS had a greater proportion of butyrate (P = 0.03) than CON. Performance data from Exp. 1 and 2 indicate that including WDGS in the SFC-based diets for newly received cattle can be an effective at concentrations up to 37.5% of the DM. In vivo measurements are needed to corroborate the in vitro fermentation changes noted with addition of WDGS.

Effects of roughage source and distillers grain concentration on beef cattle finishing performance, carcass characteristics, and in vitro fermentation.

Two experiments were conducted to evaluate the effects of wet distillers grains plus solubles (DG) and roughage source on finishing cattle performance, carcass characteristics, and in vitro fermentation. In Exp. 1, crossbred beef steers (n=224, initial BW=349 kg) were used in a randomized complete block design with a 2 × 3 + 1 factorial arrangement of treatments. Experimental diets were a standard steam-flaked corn (SFC)-based control (no DG and 10% alfalfa hay), and either 15 or 30% DG (DM basis) with roughage sources of alfalfa hay (15-AH and 30-AH), Coastal bermudagrass hay (15-BG and 30-BG), or sorghum silage (15-SS and 30-SS). Within each DG concentration, roughages provided an equivalent percentage of NDF to 7.5% AH. Steers consuming 15% DG had greater (P < 0.04) final BW, ADG, and G:F than those fed 30% DG. Feeding AH as the roughage source with DG resulted in decreased final shrunk BW and ADG (P < 0.02) compared with BG and SS. Feeding SS as the roughage source decreased (P=0.01) G:F relative to BG. Hot carcass weight was greater (P < 0.01) for steers consuming 15 vs. 30% DG, tended to be least for diets with AH as the roughage source (P=0.06), and did not differ for the control vs. the other diets (P=0.86). Control cattle had an increased (P=0.05) proportion of USDA Choice or greater carcasses compared with the average of the other treatments. In Exp. 2, the same 2 × 3 +1 factorial arrangement as in Exp. 1 was used to examine the effects of roughage source and DG on IVDMD, culture fluid osmolality, and gas production kinetics. In vitro DMD tended (P < 0.09) to be greater for BG compared with SS at 6 and 36 h of incubation and was greater for AH vs. the mean of BG and SS at 18 h (P=0.01). Culture fluid osmolality, asymptotic maximal gas production, fractional rate of gas production, and lag time of gas production did not differ among treatments (P > 0.14). Overall, feeding 15% DG in SFC-based diets increased ADG, BW, and HCW relative to 30% DG. In addition, feeding AH tended to decrease ADG, final BW, and HCW relative to the other 2 roughage sources, whereas BG improved G:F over SS. These data suggest that including the smaller amount of DG and BG as the roughage source resulted in improved performance relative to other combinations, and that substituting roughages on the basis of equivalent NDF concentration might not be ideal for optimizing performance when feeding SFC-based finishing diets that contain DG.

Substrate utilization and dose response to insulin by subcutaneous adipose tissue of Angus steers fed corn- or hay-based diets.

We hypothesized that, at a common age endpoint, adipose tissue from corn-fed steers would be less sensitive to insulin than adipose tissue from hay-fed steers. Angus steers were assigned to either a corn-based diet (n = 6) or hay-based diet (n = 6) and fed to common days on feed. Steers fed the corn-based diet had 2.44 cm of fat thickness over the 12th thoracic rib, whereas hay-fed steers had 1.04 cm of fat thickness. At slaughter, subcutaneous adipose samples were collected and portions of subcutaneous adipose tissue were incubated with [U-(14)C]acetate to quantify fatty acid synthesis or with [U-(14)C]glucose to assess glucose utilization in the presence of 0, 100, or 500 ng/mL of insulin. Additional subcutaneous samples were used to evaluate glycolytic intermediate concentrations as indicators of glycolytic flux. Data were analyzed as a split-plot with diet in the main plot and insulin concentration and its interaction with diet in the sub-plot. Within diet, linear and quadratic contrasts of insulin concentration were tested. Diet had no effect (P > or = 0.31) on glucose metabolism or acetate carbon incorporation into total lipids (P = 0.32). Insulin had no effect (P > 0.21) on glucose conversion to CO(2), lactate, or total lipids, nor did it affect (P = 0.28) acetate conversion to total lipids. No diet x insulin interaction (P > 0.36) was observed for any measure of subcutaneous metabolism in vitro. Steers fed the corn-based diet exhibited neither a linear (P > 0.22) nor a quadratic (P > 0.24) effect to increasing insulin concentration. However, when steers were fed the hay-based diet, there was a positive linear (P = 0.06) effect for glucose oxidation. These results suggest that subcutaneous adipose tissue may become resistant to stimulation by insulin in steers fed to a fat thickness above the average feedlot steer, but this is independent of diet.

Adaptation of beef cattle to high-concentrate diets: performance and ruminal metabolism.

The diet adaptation period is widely considered a critical period of time in which nutritional management practices can promote or impair subsequent performance and health. Performance studies indicate that adapting feedlot cattle with incremental increases in dietary concentrate, from approximately 55 to 90% of diet DM, in 14 d or less, while allowing ad libitum access to the diet, generally results in reduced performance during adaptation or over the entire feeding period. However, the number of cattle involved in these studies does not allow insight into the frequencies of metabolic disorders associated with the management practices tested. Adapting cattle by restricting the quantity of higher-concentrate diets offered shows promise for improving production efficiency, but further development is needed for application in commercial feedlots. Evidence suggests considerable diversity in the ability of animals to cope with ingested cereal grain, and indicates that diet adaptation procedures should affect the frequency of health-impaired or low-performing cattle in a pen. Individuals that seem to effectively regulate voluntary feed intake during adaptation generally display a steady increase in DMI as dietary concentrate is increased. These data also highlight a seemingly counterproductive, repeating cycle of overconsumption, followed by a pronounced reduction in ruminal pH, by cattle that appear to cope less favorably with grain adaptation. At least a portion of this diversity may relate to the maintenance of protozoal populations. Increases in amylolytic bacteria seemed to follow the increment of additional concentrate. Protozoa were most numerous when the diet contained approximately 60% concentrate, and lactate-utilizing bacteria increased more markedly when the diet contained more than approximately 70% concentrate. Available in vivo data suggest that the number of lactate-utilizing bacteria may reach a plateau for a given diet composition after 2 to 7 d, but thorough assessments of the time course of events using modern techniques are lacking. Further research is needed to characterize how the quantity and frequency of increases in cereal grain consumption, reflective of industry practices, impact microbial dynamics, and to identify the biological features that allow certain animals to adapt more readily to high-concentrate diets.