Crossbred Angus Steers Research Articles

319 Effects of repeated exposure to either energized or non-energized prods on the behavioral responses of beef cattle to handling

Abstract The cattle industry has adopted the use of low stress handling aids however, the continuous-pulse electric prod is still used on hard-to-move cattle. This study aimed to assess behavioral responses of beef cattle after five consecutive exposures to either energized or non-energized prods for 1 s while enclosed in a squeeze chute. A total of 208 7–8 mo old crossbred Angus steers (487.6 ± 41.68 kg BW) were randomly assigned to 1 of 4 treatments: non-energized prod (CT), continuous-pulse electric prod (CP), broken-pulse electric prod (BP) and a vibration prod (VP) that did not produce a shock. Prior to (d -3, -2 and -1; baseline), during (d 0, 1, 2, 3 and 4) and after (d 5, 6 and 7) the application of treatments, behavior of each steer was assessed including: using voice and touch (VAT; score), race transit time (RTT; s), squeeze chute score (SC; score) and flight speed (FS; m/s). Data was analyzed using GLIMMIX procedure of SAS including treatment, day and interaction as fixed effects. No treatment effect (P > 0.05) was found for VAT. The VP steers had greater (P < 0.05) RTT on d 4 and 5 compared to CT and CP, respectively. The CP steers had greater (P < 0.05) SC than CT, BP and VP. The CP had greater (P < 0.05) FS from d 0 to 7 compared to all other treatments with the exception that no differences (P > 0.05) were observed on d 1 between CP and BP. Based on SC and FS, the CP prod was more aversive to cattle than all other prods. However, due to the lack of differences in VAT and RTT measures between control and electric prods, further studies are required to determine the aversiveness of prods balanced with their ability to move hard-to-move cattle.

Evaluation of Pearl Millet With and Without Soybean Hull Supplementation for Forage-Finished Beef Production Systems

ObjectivesThe objective of this research was to evaluate pearl millet, a warm-season annual grass, with and without soybean hull supplementation for forage-finished beef production systems in the Southeast.Materials and MethodsEach year, 32 Angus-crossbred steers (339 ± 40 kg) were randomly assigned to one of four finishing treatments. Treatments were arranged in a 2 × 2 factorial and included two varieties of pearl millet, ‘Tifleaf 3’ (PM) and ‘Exceed’ brown mid-rib (BMR), and two levels of soybean hull supplementation, 0 and 0.75% of body weight d–1. Steers were on treatments for 90 and 84 d during the summers of 2017 and 2018, respectively, at the University of Georgia Department of Animal and Dairy Science Beef Research Unit located near Eatonton, GA. Shrunk weights were taken at initiation and termination of the finishing period and average daily gains (ADG) were calculated. At the end of the finishing period, steers were harvested under USDA inspection and carcass data was collected 24 h postmortem from the right side of each carcass. Striploins were then removed from the right side, vacuum packed, and allowed to age for 21 d prior to fabrication. Striploins were fabricated into 2.54-cm steaks and allocated to meats proximate (n = 1), 0 through 7 d of simulated shelf life (n = 8), trained sensory panel (n = 2), and instrumental tenderness analyses (n = 2). All data were analyzed using PROC GLIMMIX in SAS v. 9.4.ResultsSupplementation increased ADG over forage alone (P < 0.01) however, hot carcass weights were increased by supplementation in the PM steers only (P < 0.05). No treatment differences were observed for marbling score (P = 0.61), overall maturity (P = 0.49), 12th rib fat thickness (P = 0.21), ribeye area (P = 0.1668), and subjective fat color (P = 0.93). Objective carcass lean color values for L* and subjective lean color scores were different (P < 0.05). Treatment effects were also observed for carcass lean maturity scores (P < 0.05). No treatment differences were observed for meats proximate analysis (P > 0.05), instrumental tenderness as measured by Warner-Bratzler shear force (P = 0.94), initial and sustained tenderness (P = 0.66 and P = 0.29, respectively), beef and off-flavor intensities (P = 0.83 and P = 0.36, respectively), or juiciness (P = 0.54) as measured by a trained sensory panel. No treatment differences (P > 0.05) were observed for lipid oxidation or color change (Delta E) within any day of simulated shelf life. Calculated values for hue, chroma, and redness were unaffected (P > 0.05) by treatment within day of simulated shelf life.ConclusionResults indicate pearl millet is a viable forage option for forage-finished beef systems and soybean hull supplementation improves animal performance over forage alone with minimal impacts on carcass characteristics, meat quality, and shelf life.

Evaluation of Pearl Millet With and Without Soybean Hull Supplementation for Forage-Finished Beef Production Systems

ObjectivesThe objective of this research was to evaluate pearl millet, a warm-season annual grass, with and without soybean hull supplementation for forage-finished beef production systems in the Southeast.Materials and MethodsEach year, 32 Angus-crossbred steers (339 ± 40 kg) were randomly assigned to one of four finishing treatments. Treatments were arranged in a 2 × 2 factorial and included two varieties of pearl millet, ‘Tifleaf 3’ (PM) and ‘Exceed’ brown mid-rib (BMR), and two levels of soybean hull supplementation, 0 and 0.75% of body weight d–1. Steers were on treatments for 90 and 84 d during the summers of 2017 and 2018, respectively, at the University of Georgia Department of Animal and Dairy Science Beef Research Unit located near Eatonton, GA. Shrunk weights were taken at initiation and termination of the finishing period and average daily gains (ADG) were calculated. At the end of the finishing period, steers were harvested under USDA inspection and carcass data was collected 24 h postmortem from the right side of each carcass. Striploins were then removed from the right side, vacuum packed, and allowed to age for 21 d prior to fabrication. Striploins were fabricated into 2.54-cm steaks and allocated to meats proximate (n = 1), 0 through 7 d of simulated shelf life (n = 8), trained sensory panel (n = 2), and instrumental tenderness analyses (n = 2). All data were analyzed using PROC GLIMMIX in SAS v. 9.4.ResultsSupplementation increased ADG over forage alone (P 0.05), instrumental tenderness as measured by Warner-Bratzler shear force (P = 0.94), initial and sustained tenderness (P = 0.66 and P = 0.29, respectively), beef and off-flavor intensities (P = 0.83 and P = 0.36, respectively), or juiciness (P = 0.54) as measured by a trained sensory panel. No treatment differences (P > 0.05) were observed for lipid oxidation or color change (Delta E) within any day of simulated shelf life. Calculated values for hue, chroma, and redness were unaffected (P > 0.05) by treatment within day of simulated shelf life.ConclusionResults indicate pearl millet is a viable forage option for forage-finished beef systems and soybean hull supplementation improves animal performance over forage alone with minimal impacts on carcass characteristics, meat quality, and shelf life.

Effects of Mannheimia haemolytica challenge with or without supplementation of Saccharomyces cerevisiae boulardii strain CNCM I-1079 on immune upregulation and behavior in beef steers.

Objectives of this experiment were to examine the effects of live yeast (LY) supplementation on immunological, physiological, and behavioral responses in steers experimentally challenged with Mannheimia haemolytica (MH). Thirty-six crossbred Angus steers (BW = 352 ± 23 kg) seronegative for MH were allocated within a 2 × 2 factorial arrangement: Factor 1 = roughage-based diet with LY (Saccharomyces cerevisiae boulardii CNCM I-1079, 25 g·per steer daily) or negative control (CON). Factor 2 = bronchoselective endoscopic inoculation with MH or phosphate buffer solution (PBS). Steers were fed their respective diets for 28 d prior to MH challenge on day 0. Reticulo-rumen temperature (RUT; ThermoBolus, Medria) was measured continuously at 5-min intervals and rectal temperature on days -4, 0, 1, 2, 3, 5, 7, 10, and 14 relative to MH inoculation. Compared with PBS-treated steers, the steers inoculated with MH had increased (P < 0.05) RUT from 2 to 24 h, reaching a zenith (>41 °C) 9 to 11 h post-MH challenge, whereas rectal temperature was increased (P < 0.04) in MH-inoculated steers on day 1 post-MH challenge. Supplementation with LY increased (P < 0.05) rectal temperature on days 0, 7, and 10, relative to CON steers. There were inoculation x day interactions (P < 0.01) for lymphocyte, neutrophil, leukocyte, and haptoglobin concentrations. Steers challenged with MH had increased (P < 0.05) neutrophil concentration from days 1 to 3, leukocyte concentration on days 1 and 2 and haptoglobin concentration on days 1 to 5 post-MH challenge compared with PBS-treated steers. Steers supplemented with LY exhibited increased (P < 0.02) cortisol throughout the study compared with the CON treatment. Following inoculation, MH-challenged steers exhibited reduced (P < 0.05) DMI, eating rate, frequency, and duration of bunk visit (BV) events compared with PBS-treated steers. Results from this study demonstrate that the experimental challenge model effectively stimulated acute-immune responses and behavioral changes that are synonymous with naturally occurring bovine respiratory disease (BRD). However, supplementation with LY minimally altered the impact of the MH challenge on physiological and behavioral responses in this study. Continuously measured RUT was more sensitive at detecting febrile responses to MH challenge than rectal temperature. These results serve to guide future research on behavioral and physiological alterations exhibited during a BRD infection.

Analysis of Growth Intensity and Carcass Characteristics of Wagyu-Aberdeen Angus Crossbred Steers

The aim of this study was to evaluate growth ability (weight, daily weight gains) and selected carcass characteristics during fattening period of Wagyu × Aberdeen Angus crossbred steers (F1). A total of 72 animals were evaluated over a period of 4 years. The observed animals were monitored from rearing (8 months) to slaughter (30 months). Statistical evaluation was performed by SAS 9.3 (GLM procedure); variables were corrected for effects of the year, season of birth and sire effect. Sire effect proved to be the most significant in our evaluation. Offsprings sired by Bull 1 had significantly (P &lt; 0.05) better growth ability than offsprings of other two tested bulls. Slaughter analysis of tested steers showed, that mean value of dressing percentage was 55.61 %. Significantly highest dressing percentage was found for Bull 1 offsprings (56.72 %, P &lt; 0.05). The average carcass weight of tested steers was 443.46 kg and the highest carcass weight was again achieved by offsprings of Bull 1 (486.39 kg; P &lt; 0.05). Average value of beef marbling score was 5.21. Slaughter analyses of carcass cuts (cut‑out, round, chuck, rump, tenderloin, shank, flank) and tallow showed that average weight of these lean cuts was 127.32 kg and tallow content was 39.31 kg at average. The highest values of these parameters were observed in offspring of bulls Bull 1 (P &lt; 0.05).

Effect of condensed tannin extract supplementation on growth performance, nitrogen balance, gas emissions, and energetic losses of beef steers.

Condensed tannins (CT) may decrease greenhouse gas emissions and alter the site of N excreted by ruminants. We evaluated the effect of top-dressing a steam-flaked corn-based finishing diet (14.4% CP and NEg 1.47 Mcal/kg) for beef cattle with a commercially available CT extract at 3 levels (0, 0.5, and 1.0% of diet, DM basis). Angus-crossbred steers ( = 27; 350 ± 32 kg initial BW) were individually fed via Calan gates for 126 d. Diet digestibility and N balance were estimated after 34 and 95 d on feed (Phase 1 and Phase 2, respectively) using titanium dioxide as a marker of fecal output and the creatinine:BW ratio as a marker for urine output. Ruminal CH and metabolic CO fluxes were measured using a GreenFeed system (C-Lock Inc., Rapid City, SD) for 2 sampling periods that coincided with fecal and urine sampling. Urine energy loss was estimated from urine N excretion, assuming all excreted N was urea. Oxygen consumption was estimated from CO production assuming a respiratory quotient of 1.05. Average daily gain (2.08, 2.14, and 2.08 kg/d for 0, 0.5, and 1.0% CT, respectively) and G:F did not differ ( = 0.88) among treatments. Starch intake and OM intake did not differ ( ≥ 0.42) among treatments during each phase. Apparent total tract starch digestibility during Phase 1 linearly decreased ( = 0.04) with inclusion of CT. Apparent total tract digestibility of OM and starch were not different among treatments ( ≥ 0.13) during Phase 2. Nitrogen intake did not differ ( ≥ 0.16) among treatments during each phase, but fecal N excretion linearly increased ( = 0.05) with inclusion of CT during Phase 1. Urinary N excretion was not different ( ≥ 0.39) among treatments during both phases, but urinary N as a proportion of total N excretion linearly decreased ( = 0.01) when CT was included in the diet during Phase 1. Retained N was not different ( ≥ 0.27) among treatments during each phase. Fluxes of CO were similar ( ≥ 0.37) among treatments during both phases. No differences ( ≥ 0.23) were observed for percentage of GE intake lost as CH (2.99, 3.12, and 3.09% in Phase 1 and 3.54, 3.55, and 4.35% in Phase 2) for 0, 0.5, and 1.0% CT, respectively. No difference ( ≥ 0.42) was observed for heat production lost as a percent of GE intake during both phases. Growth performance, gas emissions, and energetic losses were not affected by the inclusion CT in a steam-flaked corn-based finishing diet.

The Effects of Ractopamine and Hormonal Growth Promotants on Growth and Meat Quality of Crossbred Angus Steers

ObjectivesMeat tenderness is an important quality parameter that influences consumer preference. The cattle industry has over the years seen the emergence of feed additives and hormonal growth promotants in the form of β-adrenergic agonists (β-AA) and steroids, respectively. The objective of this study was to analyze the effect of hormonal growth implants and ractopamine on slaughter weight and meat quality parameters of steers selected for high (inefficient) and low (efficient) residual feed intake (RFI) performance.Materials and MethodsForty-eight crossbred Angus steers identified from individual GrowSafe data as high (n = 21) or low (n = 27) RFI cattle were randomly assigned to pens according to treatment (n = 12). Treatments included control (no ractopamine hydrochloride (RAC)/no steroids), RAC and steroids, steroids only, and RAC only in a 2x2x2 factorial design. Steers on steroid treatment received a first implant (200mg progesterone, 20mg estradiol benzoate and 29mg tylosin tartrate) at about 350 d of age and 450kg live weight and a terminal implant (120 mg trenbolone acetate and 24mg estradiol) at about 100 d before slaughter. RAC was fed to the appropriate group 28 d before slaughter at a rate of 200mg head–1d–1. Cattle were slaughtered at about 16 mo of age over 6 consecutive weeks by weight and back fat, with 1 animal per treatment represented in each kill for a total of 8 animals slaughtered per week. Hot carcass weights (HCW) were recorded. Gluteus medius (GM) muscles were obtained from the carcasses 3 d post mortem and halved for ageing, with one half aged a further 12 d under vacuum. After ageing at 4°C, muscle halves were assessed for pH, color, drip loss and Warner-Bratzler shear force (WBSF). For all data the experimental unit was the steer as the effect of ageing was not considered. Data was analyzed using the General Linear Model procedure in SAS (SAS Inst. Inc., Cary, NC) with RFI, steroids, RAC and their interactions as fixed factors with slaughter day used as a covariate. Mean differences were determined using Least Square Means and Tukey’s multiple comparisons.ResultsResults revealed no effect (P > 0.05) of RFI and RAC on slaughter weight (SW) but steroids increased (P < 0.0001) SW of steers. An interaction effect (P = 0.0381) was seen between RFI, steroids and RAC on HCW, where high RFI steers that were implanted with steroids and fed RAC had a higher HCW at 389.64 ± 8.70 kg than low RFI steers that were neither implanted nor fed RAC (325.68 ± 7.05kg). An interaction between RFI, steroids and RAC (P = 0.045) for drip loss was observed on muscles aged for 12 d, where high RFI steers that were implanted but not fed RAC had a higher drip loss (1.93 ± 0.23 g) than low RFI steers that were not implanted but feed RAC (0.63 ± 0.19g). Muscles from implanted steers had a higher mean WBSF value than muscles from non-implanted steers on d 12 post-mortem (P = 0.039), while high RFI steers that received RAC had the lowest mean WBSF (P = 0.015).ConclusionResults indicated that steroids compromised the development of tenderness during post mortem ageing in the GM. This suggests that the benefit of steroid use on slaughter and hot carcass weights will compromise tenderness of this muscle. Additional post mortem ageing beyond 12 d may be required. Conversely, the use of the β-AA RAC showed potential for decreasing cooked GM toughness in high RFI steers regardless of the ageing period.

Effects of molasses and crude glycerol combined in a liquid supplement on ruminal fermentation in beef steers consuming bermudagrass hay.

Two experiments were performed to evaluate the effects of 1) increasing supplementation doses of a 50:50 (as-fed) liquid supplement of molasses and crude glycerol (M:G) on ruminal fermentation parameters and blood urea nitrogen (BUN) in beef steers consuming Tifton 85 bermudagrass ( spp.) hay and 2) different proportions of molasses and crude glycerol in a liquid supplement on in vitro fermentation and gas production kinetics. For Exp. 1, 8 ruminally cannulated, Angus-crossbred steers were used in a duplicated 4 × 4 Latin square design, had ad libitum access to Tifton 85 bermudagrass hay, and were randomly assigned to 1 of 4 treatments: 1) CTRL, no supplementation; 2) SUP1, 0.45 kg/d (as fed) of 50:50 M:G; 3) SUP3, 1.36 kg/d (as fed) of 50:50 M:G; and 4) SUP5, 2.27 kg/d (as fed) of a 50:50 M:G. For Exp. 2 in vitro batch cultures were conducted to test the same treatments from Exp. 1 and effects of different proportions of a M:G mixture (100:0, 75:25, 50:50, 25:75, and 0:100) when added to a hay substrate simulating the proportions of hay and liquid supplement used in SUP5. In Exp. 1, increasing doses of liquid supplement linearly decreased ( < 0.001) concentrations of NH-N, BUN, and acetate molar proportions, whereas propionate ( = 0.002) and butyrate ( < 0.001) molar proportions increased linearly. Treatment × time interactions were observed for ruminal pH ( < 0.001), where the greatest decrease was observed at 3 h postfeeding for animals consuming SUP5 (from 6.82 at 0 h to 6.32 at 3 h). In Exp. 2, decreases in acetate molar proportions ( < 0.001) and increases ( < 0.001) in propionate and butyrate molar proportions were also observed for either increasing doses of a 50:50 mixture or increasing proportions of glycerol in the mixture. Total VFA and in vitro organic matter digestibility were increased linearly ( < 0.001) as doses of a 50:50 mixture increased. Increasing doses of 50:50 M:G to growing beef heifers consuming bermudagrass hay caused a shift in VFA profile toward increases in propionate and decreases in acetate molar proportions. This was also confirmed in vitro, as the proportions of crude glycerol increased in a molasses:crude glycerol mix. Thus, molasses and crude glycerol combined seem to be useful to enhance performance in growing cattle consuming forage-based diets.

The effects of different flooring types on the behavior, health, and welfare of finishing beef steers.

Raising beef cattle on concrete floors can negatively impact their welfare by increasing joint swelling and body lesions, as well as abnormalities in resting behavior and postural changes. We hypothesized that the addition of rubber mats to concrete pens would improve beef cattle welfare by improving performance, health, hygiene, and resting behavior. Forty-eight crossbred Angus steers were housed in pens of 4 and randomly assigned to a single flooring treatment: (1) fully slatted concrete (CON), (2) fully slatted rubber mat (SLAT), or (3) solid rubber mat (SOLID; 60% of pen floor) from 36 to 48 wk of age. Weight, ADG, lesions, gait score, joint swelling, and animal and pen cleanliness were collected every 2 wk. Behavioral time budgets and frequency of postural changes (an indicator of floor traction and comfort) were collected at 0, 6, and 12 wk. No differences in weight gain or ADG were observed. Steers on SOLID flooring (0.80 ± 0.08) showed increased lesions compared to SLAT (0.38 ± 0.08) and CON (0.37 ± 0.08; both, = 0.05); however, there was no difference between SLAT and CON. SLAT steers (1.69 ± 0.04) showed a reduced gait score compared to SOLID (1.95 ± 0.04) and CON (1.98 ± 0.04; both, < 0.05), but SOLID and CON did not differ. Steers on SLAT flooring had less joint swelling (both knees and hocks) compared to SOLID and CON (all comparisons, < 0.05), but SOLID and CON did not differ. Steers on SOLID (3.64 ± 0.05) flooring were dirtier than those on SLAT (2.27 ± 0.05) and CON (2.19 ± 0.05; both, < 0.001), whereas SLAT and CON were similar. Additionally, SOLID and SLAT pens were less clean than CON pens ( < 0.001 and = 0.094, respectively), and SOLID was less clean than SLAT ( < 0.001). Time budget behavior was affected by treatment ( = 0.043), where SOLID differed from CON and SLAT (both, < 0.05). Steers on SOLID flooring preferred to rest on the rubber mat vs. slatted concrete ( = 0.001). Steers on SLAT flooring changed their posture more frequently than those on SOLID and CON flooring (both, < 0.05), but SOLID and CON did not differ. Compared to CON steers, SOLID steers showed an increase in lesions and a reduction in cleanliness, whereas SLAT steers showed a decrease in gait score and joint swelling and an increase in postural changes. Combined, these data suggest that the addition of slatted rubber mats to concrete pens may improve beef cattle welfare.

Feeding ferric ammonium citrate to decrease the risk of sulfur toxicity: effects on trace mineral absorption and status of beef steers.

The objective of this study was to determine the effects of adding ferric ammonium citrate (FAC; 300 mg ferric Fe/kg DM) to a 0.51% S diet on diet digestibility, mineral balance, and 56-d performance of steers fed a high concentrate diet. Angus-crossbred steers (n = 18) were randomly assigned to 1 of 3 treatments: 1) control diet (0.21% S; CON), 2) CON + sodium sulfate (0.51% S; high S [HS]), and 3) the HS diet + 300 mg of ferric Fe from FAC/kg DM (0.51% S; HS+Fe). This study included 2 phases, 1) a metabolism trial (d -1 to 20) and 2) a 56-d feedlot trial (d 22 to 79). In phase 1, 2 groups of 9 steers (370 ± 9.5 kg) were adapted to diet (10 d) and metabolism stalls (5 d), and following the adaptation period, a 5-d total collection of feces and urine was conducted. Feed offered and refused was recorded daily, and diet digestibility and retention of Cu, Fe, Mn, and Zn was determined. In phase 2, steers (384 ± 11.9 kg) were individually fed their respective diet in feedlot pens for 56 d and ADG was determined. From each steer, jugular blood and a liver biopsy were collected on d -1, 41, and 72 and d -1 and 72, respectively, for mineral content. Ruminal hydrogen sulfide concentrations (n = 18) were determined on d -1, 9, 23, 31, 41, 51, 61, and 72. In phase 1, DMI (P = 0.02), fecal output (P = 0.06), and intake of Cu, Mn, and Zn (P ≤ 0.04) were less in steers consuming the high S diets than CON, but DM and OM digestibility and urine excretion of minerals were not different (P ≥ 0.12) due to treatment. As a percent of intake, urinary excretion of Cu tended (P = 0.07) to be greater in the HS steers than the CON and HS+Fe steers, which did not differ (P = 0.74). In phase 2, BW, ADG, and G:F were not different (P ≥ 0.29) due to treatment, but DMI was lesser (P < 0.01) in the HS+Fe steers than CON and HS steers, which did not differ (P = 0.13). Ruminal hydrogen sulfide concentrations were greater (P < 0.01) in the steers fed high S diets than CON but were not different (P = 0.86) among the high S diets. Plasma Cu, Fe, and Zn concentrations were not different (P ≥ 0.27) due to treatment on all days. Final liver Cu concentrations were lesser (P < 0.01) in the steers fed high S diets compared with the CON, while liver Fe, Mn, and Zn concentrations did not differ (P ≥ 0.28) among treatments. In conclusion, adding Fe to a high S diet did not affect DM or OM digestibility or trace mineral absorption and status of steers relative to the HS diet alone.

Postgraze assessment of toxicosis symptoms for steers grazed on toxic endophyte-infected tall fescue pasture1,2

A 2-yr pen experiment was conducted using 12 different crossbred Angus steers each year to determine if short-term changes in prolactin concentrations, body temperature, and vasoconstriction reflect recovery from fescue toxicosis after steers that previously grazed toxic endophyte (Neotyphodium coenophialum)-infected Kentucky 31 tall fescue [Lolium arundinaceum (Schreb.) Darbysh] are placed on nontoxic feed. Groups of 6 steers from toxic endophyte-infected and endophyte-free tall fescue grazing treatments were blocked by BW for assignment to pens as a randomized complete block design with 2 replications. Two environments were implemented by initiating the experiment on 18 August in yr 1 and on 8 September in yr 2 for durations of 30 and 21 d, respectively. Rectal temperatures were recorded, jugular blood was collected for assaying serum prolactin, and cross sections of the caudal artery were ultrasonically imaged at selected time points to evaluate temporal changes in the response variables. Rectal temperatures in steers on the toxic endophyte pasture treatment declined (P < 0.05) linearly over time in yr 1 and 2 and were similar (P > 0.10) to those on endophyte-free treatment on d 30 in yr 1 and by d 15 in yr 2. Prolactin concentrations in steers on the toxic endophyte pasture treatment showed curvilinear increases (P < 0.05) over time and were similar (P > 0.10) to steers on the endophyte-free treatment by d 15 in yr 1 and by d 10 in yr 2. Luminal areas of the caudal artery in toxic endophyte steers were less (P < 0.05) than those in endophyte-free steers across all dates in both years. Results indicated that rectal temperatures in steers after they are removed from toxic fescue may decrease over time, but temporal changes in rectal temperatures could be affected more by prevailing ambient temperatures than by actual mitigation of fescue toxicosis. Prolactin concentrations in steers after they are removed from toxic endophyte tall fescue can increase and stabilize in less than 2 wk, but alkaloid-induced vasoconstriction that causes a vulnerability to severe heat stress is not alleviated within 30 d.

Mitochondrial complex I protein differs among residual feed intake phenotype in beef cattle

Four experiments were performed to determine if residual feed intake (RFI) was related to mitochondrial complex I (CI) protein. For Exp. 1, crossbred Angus steers (initial BW 270 ± 2.0 kg) were fed for a total of 170 d (n = 72). For Exp. 2, crossbred Braunvieh steers (initial BW 280 ± 3.0 kg) were fed for a total of 150 d (n = 50). For Exp. 3, crossbred Braunvieh heifers (initial BW 260 ± 3.0 kg) were fed for a total of 160 d (n = 40). For Exp. 4, crossbred Angus steers (initial BW 290 ± 3.0 kg) were fed for a total of 160 d (n = 40). All cattle in all experiments were fed the same diet. The variable RFI was calculated as the difference between predicted and actual DMI. Predicted DMI was calculated from regressing intake on ADG and metabolic body weight. Blood was collected, lymphocytes were isolated, and antibody used to capture CI. For Exp. 1, 2, and 3, CI quantity was measured using an ELISA commercial kit (Mitosciences, OR). For Exp. 4, CI subunits were separated by gel electrophoresis and bands were analyzed for differences in concentration (absorbance) among RFI phenotypes. For all 4 experiments, there was a significant difference (P < 0.05) between RFI and DMI but no difference (P > 0.05) was reported for ADG and metabolic midweight. For Exp. 1, 2, and 3, CI concentration in mitochondria was greater (P < 0.05) for low RFI compared with other treatments. For Exp. 4, animals with low RFI had a trend (P = 0.07) for greater concentration of Band I (protein S1) than high RFI. Correlation between RFI and Band I was -0.72 (P = 0.04). We concluded that mitochondrial function was at least in part responsible for differences among animals in metabolic efficiency.

Effects of feeding corn modified wet distillers grain plus solubles co-ensiled with direct-cut forage on feedlot performance, carcass characteristics, and diet digestibility of finishing steers1

Two experiments were conducted to evaluate the effects of feeding corn modified wet distillers grain plus solubles (MWDGS) co-ensiled with direct-cut forage (DC) to beef steers, on feedlot performance and total tract digestibility. In Exp. 1, sixty-four crossbred Angus steers (n = 64; 329 ± 43 kg) were blocked by BW and randomly assigned to 1 of 4 dietary treatments: 1) corn-silage and soybean meal (CON), 2) DC co-ensiled with MWDGS (CO-EN), 3) haylage mixed with MWDGS at feeding (H+WDG), and 4) haylage mixed with dry distillers grains plus solubles at feeding (H+DDG). Steers were harvested when they reached an endpoint of 1.1 cm of 12th-rib back fat. In Exp. 2, four ruminally cannulated beef steers (initial BW = 556 ± 31 kg) were used in a 4 × 4 Latin square to evaluate digestibility of diets used in Exp. 1. Experimental periods were 14 d in length with 10 d for diet adaptation and 4 d for sample collection. Three linear orthogonal contrasts were used to compare effects of 1) CON vs. diets containing distillers grains (DGD), 2) CO-EN vs. diets where distillers grains were mixed at feeding (MIX), and 3) H+WDG vs. H+DDG. In Exp. 1, DMI was less (P < 0.001) for steers fed CON compared with those fed DGD and greatest (P < 0.001) for steers fed CO-EN compared with MIX. Corn-silage- and soybean-meal-fed steers had more days on feed than those fed DGD (P = 0.001). Body weight gain (P = 0.02) was greater for CO-EN compared with MIX. Fat thickness at the 12th and 13th ribs was greater (P = 0.03) for DGD steers compared with CON steers. Hot carcass weight was greater (P = 0.03) for steers fed CO-EN compared with those fed MIX. Steers fed CON resulted in greater marbling scores (P = 0.01) compared DGD-fed steers. Longissimus muscle area was greater (P = 0.01) for CON-fed steers compared with all other treatments. In Exp. 2, no differences (P > 0.10) in DM, OM, or N intakes were observed. Apparent total tract DM (P = 0.01) and N (P = 0.02) digestibility were greatest in steers fed CON compared with all others. Steers fed DGD had less (P = 0.02) rumen NH(3) concentrations compared with CON. The CON diet resulted in greater molar concentrations of VFA (P = 0.03) and decreased acetate to propionate ratio (P = 0.03) compared with all DGD. These data suggest that feeding MWDGS co-ensiled with direct-cut forage results in reduced diet digestibility but equal or greater feedlot performance and similar carcass and characteristics when compared with a corn diet supplemented with soybean meal and diets where MWDGS and DDGS were added at the mixer.

Effects of distillers grains with high sulfur concentration on ruminal fermentation and digestibility of finishing diets1,2

Twelve ruminally cannulated crossbred Angus steers were used to evaluate ruminal fermentation characteristics and diet digestibility when 30% (DM) corn dried distillers grains with solubles (DDGS) containing 0.42 or 0.65% (DM) of dietary S was incorporated into finishing diets based on steam-flaked corn (SFC) or dry-rolled corn (DRC). The study was a replicated, balanced randomized incomplete block design with a 2 × 2 factorial arrangement of treatments. Factors consisted of dietary S concentration (0.42 and 0.65% of DM; 0.42S and 0.65S, respectively) and grain processing method (SFC or DRC). The 0.65S concentration was achieved by adding H(2)SO(4) to DDGS before mixing rations. Steers were assigned randomly to diets and individual, slatted-floor pens, and fed once daily for ad libitum intake. Two 15-d experimental periods were used, each consisting of a 12-d diet adaptation phase and a 3-d sample collection phase. Samples were collected at 2-h intervals postfeeding during the collection phase. Ruminal pH was measured immediately after sampling, and concentrations of ruminal ammonia and VFA were determined. Fecal samples were composited by steer within period and used to determine apparent total tract digestibilities of DM, OM, NDF, CP, starch, and ether extract. Feeding 0.65S tended (P = 0.08) to decrease DMI but resulted in greater apparent total tract digestibilities of DM (P = 0.04) and ether extract (P = 0.03). Ruminal pH increased (P < 0.05) in steers fed 0.65S diets, which may be attributable, in part, to decreased (P = 0.05) VFA concentrations and greater (P < 0.01) ruminal ammonia concentrations when 0.65S was fed, compared with feeding 0.42S. These effects were more exaggerated in steers fed DRC (interaction, P < 0.01), compared with steers fed SFC. Steers fed DRC-0.65S had greater (P < 0.01) acetate concentration than steers fed DRC-0.42S, but acetate concentration was not affected by S concentration when SFC was fed. Propionate concentration was decreased (P < 0.01) in steers fed SFC-0.65S compared with steers fed SFC-0.42S, but dietary S concentration had no effect on propionate concentration when DRC was fed. Butyrate concentration was less (P < 0.01) in steers fed 0.65S diets than in steers fed 0.42S. Lactate concentrations tended (P = 0.06) to decrease in steers fed 0.65S diets. Feeding DDGS with increased S concentration may decrease feed intake and ruminal VFA concentration but increase ruminal ammonia concentration.

Effects of grain processing and supplementation with exogenous amylase on nutrient digestibility in feedlot diets

Starch is the major source of energy in the diets of feedlot cattle, comprising 50% or more of the dietary DM. With limitations to starch digestion in the small intestine and low energetic efficiency of starch fermentation in the large intestine, it is important to maximize ruminal starch digestibility, while concurrently minimizing digestive disorders such as acidosis. Grain processing is the most common strategy to increase ruminal digestion of starch. Supplemental amylase has been proposed as a means of improving total tract starch digestion, but research on the effects of exogenous amylase in feedlot diets is limited. To evaluate addition of amylase to feedlot diets, 32 Angus and Angus-crossbred steers were used in a randomized complete block design with replication of treatments in the block in a 2×2 factorial arrangement. Factors included grain processing method (dry-rolled corn [DRC] or steam-flaked corn [SFC]) with or without α-amylase (RumiStar; DSM Nutritional Products, Inc., Kaiseraugst, Switzerland) supplemented at 600kilo novo units (KNU)/kg of dietary DM. One KNU is the amount of enzyme that releases 6μmol of p-nitrophenol per min at pH 7.0 and 37°C. Steers gradually adapted a 90% concentrate finishing diet for 28d, during which the DRC and SFC treatments were applied. Amylase was supplemented when steers reached ad libitum intake of the 90% concentrate diet (d 1 of experimental period). Experimental diets were fed for 42d, and 0.25% (DM basis) of Cr2O3 was included in the diet for 11d as an indigestible marker for measurement of nutrient digestibility from d 39 to 42. Supplementation with amylase did not affect nutrient digestibility (P≥0.21) or DMI, ADG, and G:F for the 42-d period (P≥0.35). The SFC diets had 28% less total tract digestibility of NDF (P<0.001) and 39% less total tract digestibility of ADF (P<0.001) than DRC-based diets. Total tract starch digestibility was increased by 5.5% (P<0.001) in SFC-based diets. Steers fed the SFC-based diets had lower DMI (P=0.04) and increased ADG (P=0.04) and G:F (P<0.001) compared with steers fed DRC-based diets. Overall, results suggest that supplementation with exogenous α-amylase at 600KNU/kg dietary DM did not affect nutrient digestibility or performance by feedlot steers. Steam flaking corn grain decreased total tract digestibility of NDF and ADF and increased total tract starch digestibility compared with dry rolling, which was associated with greater ADG and G:F.

Performance of Finishing Steers on Corn Silage or Forage Sorghum Silage with Corn Oil Supplementation1

<h2>ABSTRACT</h2> Thirty-two crossbred Angus steers (initial BW 524.9±63.3kg; age 24 mo) were fed a free-choice TMR consisting of 55% corn silage or low-grain sorghum silage and 45% concentrate mix [88.1% ground corn, 10% soybean meal, 1.9% mineral-Rumensin-vitamin premix (Rumensin, Elanco Animal Health, Indianapolis, IN)] on a DM basis, without and with corn oil (7% of DMI). A low-grain forage sorghum silage was compared with a high-grain corn silage. Steers were ranked by BW, randomly assigned to dietary treatments in a 2×2 factorial arrangement, and individually fed with Calan gates (American Calan Inc., Northwood, NH) for 78 d. Steers were implanted with Component TE-IS (trenbolone acetate, estradiol, tylosin tartrate, Ivy Animal Health, Shawnee Mission, KS) on d 1, and initial and final BW were means of 2 consecutive daily unshrunk BW. Steers were slaughtered and USDA QG were determined in a commercial abattoir at the conclusion of the experiment. Rib sections and subcutaneous fat samples were retained for fatty acid analysis. Steer 78-d ADG exhibited a silage×treatment interaction (P<0.05) in which the addition of corn oil depressed ADG for steers fed corn silage but increased ADG for steers fed sorghum silage. Steer DMI was higher for sorghum silage diets than corn silage diets (25.99 vs. 22.10kg; P<0.05); however, DMI was not affected (P>0.10) by corn oil supplementation. Despite increased DMI for steers receiving the sorghum silage treatments, 78-d ADG was higher (P<0.05) for steers receiving the corn silage treatments (ADG: sorghum silage=1.41kg vs. corn silage=1.75kg). Corn oil supplementation had no effect (P>0.10) on concentrations of the conjugated linoleic acid isomer cis-9, trans-11 in longissimus dorsi or subcutaneous fat samples. Steers fed corn oil had greater (P<0.05) concentrations of the conjugated linoleic acid isomer trans-10, cis-12 in subcutaneous tissue. Carcass traits were unaffected (P>0.10) by treatments, except for QG (12=US Choice-), which was greater for sorghum silage than corn silage. Corn oil supplementation had no effect (P>0.10) on the YG, QG, or hot carcass weight of steers. Corn oil supplementation had no effect on steer performance or on conjugated linoleic acid isomer concentrations.

Effects of Alternate Weaning Methods on Behavior, Blood Metabolites, and Performance of Beef Calves

Beef calves traditionally are weaned by abrupt remote separation from their dams. Alternate weaning strategies have been suggested to reduce stress and improve performance of calves after weaning. Two such strategies were compared with abrupt remote separation weaning in spring-born, Angus-crossbred steers. Cow-calf pairs were allotted to 3 treatments 7 d before (d−7 to 0) weaning: fence-line (FL, calves separated from dams by a fence), nose-clips (NC, placement of antisuckling device on calves which then remained with dams), or control (CTRL, calves remained with dams until d 0). All steers were transported away from their dams on d 0, placed on pasture on d 1, and maintained within weaning-method treatment groups. Behavioral observations were conducted from d−7 to−4 and d 1 to 4. The NC calves spent less time eating, more time idling, more time close to dams, walked less, and had reduced ADG compared with FL or CTRL calves before transport (P < 0.05). The CTRL calves spent less time eating, more time idling, and walked more than FL or NC calves (P < 0.05) after transport. Average daily gain of FL calves was greater than NC calves (P < 0.05). On d 0, NC calves had reduced (P < 0.05) creatine kinase and BUN concentrations and greater nonesterified fatty acid concentration. There were no treatment effects for any blood metabolite detected after transport. Nose-clip weaning did not seem to be a comparable method to FL weaning, whereas FL weaning may be an alternative to traditional weaning.

Influence of two-stage weaning with subsequent transport on body weight, plasma lipid peroxidation, plasma selenium, and on leukocyte glutathione peroxidase and glutathione reductase activity in beef calves

An experiment was conducted to assess the effects of two-stage weaning and subsequent transport on oxidative stress markers in calves. Thirty-six crossbred Angus steers (243 ± 20.8 kg; 221 ± 19.7 days) were allotted to control, fenceline (FL), and nose-clip (NC) weaning groups. Steers were weighed and blood samples were collected on days −7, 0 (pre-transit) and 7 surrounding transport. Leukocytes were analyzed for glutathione peroxidase and glutathione reductase activity, whereas malondialdehyde and Se were measured in plasma. Data were analyzed using PROC MIXED with the Tukey–Kramer adjustment applied post hoc. No treatment effects were detected for blood variables or weights. Glutathione peroxidase activity was not altered by time ( P = 0.27). Glutathione reductase activity, Se, and malondialdehyde declined ( P < 0.001) from day −7 to 7 in all steers. Treatment × date interaction was detected for malondialdehyde ( P < 0.02). Control and FL steers gained weight ( P < 0.03), whereas NC steers did not gain weight between days −7 and 0 ( P = 0.81). All weaning treatment groups gained weight between days 0 and 7 ( P < 0.05). Results suggest that two-stage weaning has little effect on examined markers of oxidative stress.

Effect of field peas, chickpeas, and lentils on rumen fermentation, digestion, microbial protein synthesis, and feedlot performance in receiving diets for beef cattle.

Two experiments were conducted to evaluate the use of pulse grains in receiving diets for cattle. In Exp. 1, 8 Holstein (615 +/- 97 kg of initial BW) and 8 Angus-crossbred steers (403 +/- 73 kg of initial BW) fitted with ruminal and duodenal cannulas were blocked by breed and used in a randomized complete block design to assess the effects of pulse grain inclusion in receiving diets on intake, ruminal fermentation, and site of digestion. Experiment 2 was a 39-d feedlot receiving trial in which 176 mixed-breed steers (254 +/- 19 kg of initial BW) were used in a randomized complete block design to determine the effects of pulse grains on DMI, ADG, and G:F in newly received feedlot cattle. In both studies, pulse grains (field peas, lentils, or chickpea) replaced corn and canola meal as the grain component in diets fed as a total mixed ration. Treatments included 1) corn and canola meal (control); 2) field pea; 3) lentil; and 4) chickpea. Preplanned orthogonal contrasts were conducted between control vs. chickpea, control vs. field pea, and control vs. lentil. In Exp. 1, there were no differences among treatments for DMI (11.63 kg/d, 2.32% of BW daily, P = 0.63) or OM intake (P = 0.63). No treatment effects for apparent ruminal (P = 0.10) and total tract OM digestibilities (P = 0.40) were detected when pulse grains replaced corn and canola meal. Crude protein intake (P = 0.78), microbial CP flow (P = 0.46), total tract CP digestibility (P = 0.45), and microbial efficiency (P = 0.18) were also not influenced by treatment. Total-tract ADF (P = 0.004) and NDF (P = 0.04) digestibilities were greater with field pea vs. control. Total VFA concentrations were lower for field pea (P = 0.009) and lentil (P < 0.001) compared with control. Chickpea, field pea, and lentil had lower (P < or = 0.03) acetate molar proportion than control. Ruminal pH (P = 0.18) and NH3 (P = 0.14) were not different among treatments. In Exp. 2, calves fed chickpea, field pea, and lentil had greater overall DMI (7.59 vs. 6.98 kg/d; P < or = 0.07) and final BW (332 vs. 323 kg; P < or = 0.04), whereas chickpea and lentil had greater ADG (1.90 vs. 1.71 kg/d; P < or = 0.04) than control. Gain efficiency (P = 0.18) did not differ among treatments. Steers fed pulse grains had similar CP and OM digestibilities compared with a combination of corn and canola meal in receiving diets. Pulse grains are a viable alternative for replacement of protein supplements in receiving diets for beef cattle.

Effects of winter stocker growth rate and finishing system on: I. Animal performance and carcass characteristics1,2

Angus-crossbred steers (n = 216) were used in a 3-yr study to assess the effects of winter stocker growth rate and finishing system on finishing performance and carcass characteristics. During winter months (December to April) steers were randomly allotted to 3 stocker growth rates: low (0.23 kg x d(-1)), medium (0.45 kg x d(-1)), or high (0.68 kg x d(-1)). Upon completion of the winter phase, steers were randomly allotted within each stocker treatment to a corn silage-concentrate or pasture finishing system. All steers regardless of finishing treatment were finished to an equal-time endpoint to eliminate confounding of treatments with animal age or seasonal factors. Upon completion of the finishing period, steers were slaughtered in 2 groups (one-half of pasture and one-half of feedlot cattle each time) and carcass data were collected. Winter data were analyzed as a completely randomized design, with winter treatment, pen replicate, year, and the winter x year interaction in the model. Finishing performance and carcass data were analyzed in a split-plot design with finishing system in the whole plot, and winter growth rate and winter x finish in the split-plot. Winter treatment mean within finishing replication was the experimental unit, and year was considered a random effect. Winter stocker phase treatments resulted in differences (P < 0.001) in final BW, ADG, and ultrasound LM area between all treatments for that phase. Pasture-finished cattle had lower (P < 0.001) final BW, ADG, HCW, LM area, fat thickness, KPH, dressing percent, USDA yield grade, and USDA quality grade. Winter stocker treatment influenced (P < 0.05) final BW and HCW, with low and medium being less than high. Steers with low stocker gain had greater (P < 0.05) finishing ADG. Dressing percent was greater (P < 0.001) for high than low, and USDA quality grade was greater (P < 0.05) for high than low and medium. Carcass LM area, fat thickness, KPH, and USDA yield grade were not influenced (P > 0.05) by winter rate of gain. Cattle on low during winter exhibited compensatory gain during finishing but were unable to catch the high group regarding BW or HCW. The USDA quality grade was greater for high than low or medium. Animal performance during the winter stocker period clearly impacts finishing performance, carcass quality and beef production in both pasture- and feedlot-finishing systems, when cattle were finished to an equal-time endpoint.