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Take a walk down memory lane as we pick out some of the most witty and pithy letters that you, dear readers, have sent us over the past three decades of Physics World.

Two hundred ninety-nine crossbred yearling steers (363 ± 15 kg initial BW) were fed for an average of 114 d in a finishing study comparing 7 diets in which steam-flaked corn was used as the principal energy source. Forty-nine pens were used in this study with 7 BW blocks, 7 pens per treatment, and 5 to 7 steers per pen. A control diet with no distillers grains with solubles (DGS) was compared with 6 diets containing 15% DGS (DM basis). The diets contained wet sorghum DGS with 0 or 6% alfalfa hay, dried sorghum DGS with 0 or 6% alfalfa hay, wet corn DGS with 6% alfalfa hay, or dried corn DGS with 6% alfalfa hay. Apparent total tract digestibilities were calculated by total collection of fecal material from the concrete-surfaced pens over a 72-h period. Dry matter intake, ADG, G:F, and carcass characteristics were similar (P≥ 0.18) for steers fed finishing diets with or without 15% DGS. However, apparent total tract digestibilities of DM and OM were 2.8% less (P≤ 0.03) for finishing diets containing 15% DGS (DM basis). Dry matter intake, ADG, G:F, apparent total tract digestibility, and carcass characteristics were not different (P≥ 0.09) for steers fed finishing diets containing sorghum or corn DGS. Dry matter intake, ADG, G:F, apparent total tract digestibility, and carcass characteristics also were not different (P≥ 0.10) for steers fed finishing diets containing wet or dried DGS. Steers fed sorghum DGS with 6% hay consumed more DM (P< 0.01) and gained more BW (P< 0.01) than steers fed diets without hay, but G:F were not different (P> 0.78). Sorghum DGS diets containing alfalfa hay were 4% less (P= 0.01) digestible than sorghum DGS diets containing no hay. Carcasses of steers fed sorghum DGS diets without hay were lighter, leaner, and had decreased USDA yield grades (P= 0.01) compared with steers fed sorghum DGS diets containing hay. Feeding moderate levels (i.e., 15%, DM basis) of DGS resulted in growth performance and carcass characteristics similar to those of cattle fed no DGS. In addition, sorghum- and corn-based DGS had similar feeding values, and wet (≈31% DM) and dried (≈91% DM) DGS also had similar feeding values. Complete removal of alfalfa hay in diets containing DGS improved diet digestibility but reduced growth performance and carcass finish.

Six hundred sixty-five crossbred beef heifers initially weighing 225 kg were used in a completely randomized design to measure plasma glucose, lactate, and urea N concentrations at time of initial processing, determine the incidence of apparent bovine respiratory disease (BRD) in receiving cattle, and evaluate the effect of apparent BRD on subsequent cattle growth and carcass characteristics. Heifers were processed within 24 h of arrival, and processing included vaccination against common viral and clostridial diseases, recording rectal temperature, and sampling whole blood for subsequent measurement of plasma glucose, lactate, and urea concentrations. Heifers were monitored for clinical signs of apparent BRD, including depression, lethargy, anorexia, coughing, rapid breathing, and nasal or ocular discharge. Heifers exhibiting signs of apparent BRD received antibiotic therapy, and the number of times a heifer was treated for apparent BRD was recorded. Following the 36-d receiving period, heifers were transported to native grass pastures and allowed to graze for 136 d. At the end of the grazing season, heifers were transported to a commercial feedlot where they were adapted to a common finishing diet offered for ad libitum consumption. Following the 124-d finishing period, heifers were slaughtered and carcass data were collected. Heifers treated for apparent BRD had decreased plasma glucose (linear, P< 0.01), lactate (linear, P< 0.01), and urea N concentrations (linear, P< 0.06) measured at time of initial processing. Rectal temperature measured at time of initial processing tended to be greater (linear, P< 0.11) for heifers treated for apparent BRD. Heifers treated for apparent BRD during the receiving period had decreased overall ADG (linear, P< 0.10), final BW (linear, P< 0.01), HCW (linear, P< 0.01), fat thickness (linear, P< 0.01), and marbling score (linear, P< 0.03). These data suggest that initial plasma glucose and lactate concentrations might be affected by the health status of receiving cattle and that increased incidence of apparent BRD in cattle decreases ADG and carcass quality.

Six hundred ten crossbred-yearling heifers (347 ± 5 kg of initial BW) were obtained and used in a randomized complete-block design finishing study. Finishing diets were based on steam-flaked corn and ground alfalfa hay. The control (CONT) treatment contained no distillers grains with solubles (DGS), the second diet was formulated to contained 13% (DM basis) dried corn DGS derived from a traditional dry-grind ethanol process (TRAD), and the third diet was formulated to contained 13% (DM basis) dried corn DGS derived from a partial fractionation dry-grind process (FRAC). Dry matter intake, ADG, and gain efficiency were not different (P≥ 0.48) for yearling heifers fed CONT when compared with heifers fed DGS. Heifers fed TRAD consumed more (P= 0.01) feed than heifers fed FRAC. However, ADG and feed efficiency were not different (P≥ 0.07) for heifers fed DGS. Moderate inclusion levels of DGS in finishing flaked corn diets yielded satisfactory performance. Growth performance was not different for heifers fed DGS originating from either ethanol processing method.

Three hundred seventy-one crossbred-yearling heifers (299 ± 9 kg initial BW) were obtained from a common source and used in a randomized complete-block designed finishing study. A 2 × 3 factorial arrangement of treatments was used with one factor being diet: based on steam-flaked corn finishing diet (SFC) or SFC plus 25% (dry basis) corn wet distillers grains with solubles (WDGS). The second factor was feed additives: no added antibiotics (NONE), 300 mg of monensin daily (MONENSIN), or 300 mg of monensin + 90 mg of tylosin daily (MON+TYL). Main effect of diet resulted in no difference in DMI (P= 0.34). Heifers fed SFC gained 9% faster (P= 0.01) and were 7% more efficient (P= 0.01) than heifers fed WDGS. In addition, heifers fed SFC had 3% heavier (P= 0.01) HCW; 1% greater (P= 0.01) dress yield; and had 3% larger (P= 0.05) LM area. Marbling score and carcasses that graded USDA Choice or better were both greater (P≤ 0.03) for heifers fed SFC. Heifers fed MONENSIN had a smaller (P= 0.01) LM area than heifers fed NONE and tended (P= 0.09) to have smaller LM area than heifers fed MON+TYL. Marbling score, USDA quality grade, and USDA yield grade were not different (P≥ 0.12) among feed additive treatments. Kidney, pelvic, and heart fat and s.c. fat thickness at the 12th rib were also not different (P≥ 0.55) for main effects of diet and feed additive. There was a tendency (P= 0.09) for a diet × feed additive interaction for the most severe (A+) liver abscesses. Heifers fed NONE yielded the greatest percentage (16%) of A+ livers in the SFC treatment, whereas heifers fed MON+TYL yielded the greatest percentage (10%) in the WDGS treatment. Including wet distillers grains with solubles in diets based on steam-flaked corn decreased finishing heifer performance, HCW, and marbling. Tylosin addition tended to decrease severity of liver abscesses in diets containing SFC, but not in diets containing WDGS. These data indicate that monensin and tylosin may not be as effective when used in steam-flaked corn diets with 25% WDGS.

Two experiments were conducted at the Kansas State University Beef Cattle Research Center to determine the effects of ractopamine-HCl (Optaflexx) on growth performance, carcass characteristics, and meat quality of finishing feedlot heifers. In Exp. 1, heifers implanted with Revalor-H (n = 302, initial BW = 479 kg) were fed steam-flaked corn diets with 0 (control) or 200 mg of ractopamine-HCl (OPT) per heifer daily for 28 d before slaughter. Average daily gain and DMI were not different between treatments (P> 0.17); however, OPT cattle tended to have a greater G:F (P= 0.06). Treatments did not differ with respect to final BW, HCW, dressing percentage, USDA yield grade, USDA quality grade, marbling score, LM area, KPH, Warner-Bratzler shear force, weight loss during cooking, or L*, a*, or b* colorimetric values during a 7-d retail display or purge loss from loin steaks during retail display (P> 0.19). In Exp. 2, nonimplanted crossbred heifers (n = 281, BW = 451 ± 2 kg) were fed finishing diets based on steam-flaked corn. A control diet (no ractopamine) was compared with diets providing 200 mg of OPT per heifer daily for periods of 28 or 42 d (200 × 28 and 200 × 42, respectively), 300 mg/d for 28 d (300 × 28), and a step-up regimen consisting of 14 d at 100 mg, followed by 14 d at 200 mg, and the final 14 d at 300 mg of OPT (step-up). Feeding OPT had no effect on carcass weight gain among treatments (P= 0.18). The efficiency of carcass gain was 34 and 35% greater (P= 0.06) for the 200 × 42 and step-up groups compared with control, respectively. Feeding OPT at 300 mg for 28 d reduced DMI compared with the control, 200 × 28, and 200 × 42 (P< 0.05) groups. Administration of OPT had no effect on marbling score, yield grade, LM area, KPH, or percentages of carcasses grading USDA Choice (P> 0.10). Feeding ractopamine-HCl (Optaflexx) to finishing heifers generally improved the efficiency of carcass gain with minimal effect on carcass characteristics. These effects were most pronounced in heifers fed ractopamine for 42 d.

Manipulation of cattle diets has been proposed as a possible preharvest control measure for Escherichia coliO157. Altering hindgut fermentation through diet changes may be a means to reduce fecal shedding of E. coliO157. In Exp. 1, the objective was to determine whether fecal shedding of E. coliO157 was related to fecal starch concentration. Beginning on d 20, and every week thereafter until d 61, steers in 54 pens (6 to 7 steers per pen) were sampled (n = 122) by fecal collection and rectoanal mucosal swabs (RAMS) for E. coliO157 and fecal starch concentration determinations. Escherichia coliO157 prevalence was 3.3% in fecal samples, 4.1% as measured by RAMS, and 4.9% by fecal or RAMS samples. Steers positive for E. coliO157 contained 21% more (P< 0.05) fecal starch than steers that were negative for E. coliO157. In Exp. 2, we attempted to alter the concentration of starch escaping rumen fermentation by feeding finishing diets based on steam-flaked corn (SFC) and dry-rolled corn (DRC) to 30 heifers prescreened for being culture positive for fecal E. coliO157. Beginning on d 13, heifers were sampled (feces and RAMS) weekly to monitor fecal pH and starch concentration, and prevalence of E. coliO157. Prevalence of E. coliO157 remained above 30% for the first 13 d, but declined (P< 0.05) over the entire 7-wk period. Based on RAMS, the prevalence of E. coliO157 tended to be greater (P= 0.08) for heifers fed SFC than for those fed the DRC diet. After d 20, heifers fed DRC had greater (P< 0.05) fecal starch and lower (P< 0.05) fecal pH than heifers fed SFC. Fecal pH was negatively correlated (r = − 0.34; P< 0.05; n = 143) with fecal starch concentration. Fecal starch concentration and pH were not different (P> 0.05) for heifers that were positive or negative for E. coliO157. Our data suggest that fecal shedding of E. coliO157 was not related to fecal pH or starch concentration in cattle fed grain-based diets.

Previous research from our laboratory has indicated that melengestrol acetate (MGA) added to the diet during the first 35 d after arrival in the feedlot improves growth rates and tends to reduce chronic respiratory disease in heifers naturally challenged with bovine respiratory disease. The current study was conducted to provide further insight into the possible immunomodulatory effects of MGA. Crossbred heifers (n = 48; 232 ± 5.5 kg of BW) were used in a randomized complete block design to determine the effects of MGA on lung pathology and markers of inflammation after Mannheimia haemolyticachallenge. On d 0, cattle were blocked by BW and randomly assigned, within block, to diets (54% concentrate) that provided 0 or 0.5 mg of MGA per heifer daily for the duration of the experiment. Inoculum containing from 1.3 × 109to 1.7 × 109cfu of M. haemolytica(20 mL) was instilled at the bifurcation of the trachea on d 14. Blood samples were collected, clinical observations were made, and rectal temperatures were recorded for each animal at 0, 12, 24, 48, 72, 96, 120, and 138 h after inoculation. Heifers fed MGA had greater circulating concentrations of eosinophils and postchallenge concentrations of segmented neutrophils and white blood cells (P< 0.01) than controls, as well as elevated plasma protein, serum haptoglobin, and fibrinogen after M. haemolyticachallenge (P< 0.01). Heifers fed MGA had lower plasma glucose (P< 0.01), greater plasma urea N (P= 0.02), and elevated respiratory indices (P< 0.01) compared with controls. Necropsies performed on d 6 after inoculation suggested that M. haemolyticachallenge was relatively mild, because lesions were confined to a small portion of the lungs. On a 0 to 100 scale, average lung lesion scores were 3 and 1 for MGA-fed and control groups, respectively (P< 0.06). Heifers fed MGA before mild M. haemolyticachallenge were more susceptible to infection, as evidenced by a greater number of heifers fed MGA exhibiting pulmonary lesions 138 h after inoculation than controls (14 out of 23 vs. 6 out of 24 for MGA and controls, respectively; P< 0.02).

An experiment was conducted to determine the relationship between feeding ractopamine and different amounts of MP on growth and carcass characteristics of feedlot heifers. Seventy-two crossbred heifers (475 kg of initial BW) were fed individually a diet based on steam-flaked corn for ad libitum intake for 29 d. Heifers were implanted with 140 mg of trenbolone acetate and 14 mg of estradiol-17β 60 d before the experiment. Treatments were arranged as a 2 × 3 factorial and included 0 or 200 mg of ractopamine-HCl (23 ppm)/ d, and urea, solvent soybean meal, or expeller soybean meal (ESBM) as the predominant protein supplement. The amounts of MP supplied by the urea, solvent soybean meal, and ESBM diets were 688, 761, and 808 g/ d, respectively, calculated according to level 1 of the NRC model. Body weights were obtained 1 d before ractopamine feeding and at slaughter. Blood samples were obtained 1 d before starting the experiment and 13 d later. Ractopamine improved ADG, efficiency of gain, carcass-adjusted ADG, and carcass-adjusted efficiency of gain (P< 0.01). For ADG, heifers demonstrated a ractopamine × protein source interaction (P< 0.05); heifers not fed ractopamine had greater ADG when fed ESBM than when fed urea, whereas for heifers fed ractopamine there were no differences (P≥ 0.10) among protein supplements. This interaction was not observed for carcass-adjusted ADG (P= 0.60). Final live weights (P= 0.02) and carcass weights (P= 0.01) were greater with ractopamine feeding. Carcass marbling scores and yield grades were not affected by ractopamine or protein source (P≥ 0.39). Plasma total α-amino N and glucose concentrations decreased more from pretreatment concentrations when heifers were fed ractopamine (P< 0.05). Feeding ractopamine to heifers for 28 d before slaughter improved ADG and efficiency of gain without any large effects on carcass characteristics. The MP supply does not need to be increased from that provided by finishing diets based on steam-flaked corn with urea as the primary N supplement to allow the maximal response to ractopamine by finishing heifers.

Two experiments were conducted to evaluate combinations of wet corn gluten feed (WCGF) and barley, as well as the particle size of dry-rolled barley and corn, in finishing steer diets containing WCGF. In Exp. 1, 144 crossbred steers (initial BW = 298.9 ± 1.4 kg) were used to evaluate barley (0.566 kg/L and 23.5% NDF for whole barley) and WCGF combinations in finishing diets containing 0, 17, 35, 52, or 69% WCGF (DM basis), replacing barley and concentrated separator byproduct. A sixth treatment consisted of corn (0.726 kg/L and 11.1% NDF for whole corn), replacing barley in the 35% WCGF treatment. In Exp. 2, 144 crossbred steers (initial BW = 315.0 ± 1.5 kg) were used to evaluate coarse or fine, dry-rolled barley or corn (0.632 and 0.699 kg/L; 26.6 and 15.9% NDF for whole barley and corn, respectively) in finishing diets containing WCGF. A factorial treatment design was used; the factors were grain source (corn or barley) and degree of processing (coarse or fine). The diets contained 50% WCGF, 42% grain (corn or barley), 5% alfalfa hay, and 3% supplement (DM basis). In Exp. 1, DMI and ADG responded quadratically (P≤ 0.03), peaking at 35 and 52% WCGF, respectively. The efficiency of gain was not affected (P≥ 0.42) by dietary treatment. Steers fed dry-rolled corn and 35% WCGF had heavier HCW, lower DMI, greater ADG, increased G:F, increased s.c. fat thickness at the 12th rib, and greater yield grades compared with steers fed dry-rolled barley and 35% WCGF (P≤ 0.04). The apparent dietary NEgwas similar among the barley and WCGF combinations (P≥ 0.51); however, the corn and 35% WCGF diet was 25% more energy dense (P< 0.001) than was the barley and 35% WCGF diet. In Exp. 2, no grain × processing interactions (P≥ 0.39) were observed. Particle size was 2.15 and 2.59 mm for fine- and coarse-rolled barley and was 1.90 and 3.23 mm for fine- and coarse-rolled corn. Steers fed a combination of corn and WCGF had increased ADG, greater G:F, heavier HCW, larger LM area, more s.c. fat thickness at the 12th rib, greater yield grades, increased marbling, and more KPH compared with steers fed a combination of barley and WCGF (P≤ 0.03). Fine-rolling of the grain increased fat thickness (P= 0.04). The addition of WCGF to the barley-based diets increased DMI and gain. Decreasing grain particle size did not greatly affect performance of the steers fed the 50% WCGF diets; however, carcasses from the steers fed the fine-rolled grain contained more fat.

Performance and digestibility experiments were conducted to determine the influence of moisture and flake density (FD) on the feeding value of steam-flaked corn (SFC). Dietary treatments consisted of finishing diets that contained 78% (DM basis) SFC that was tempered using 0, 6, or 12% moisture and processed to either 360 (SF28) or 310 (SF24) g/L. A 3 × 2 factorial arrangement of treatments was used. In Exp. 1, 78 steers were individually fed the respective treatments for 106 d. Moisture added during tempering tended (linear; P< 0.10) to increase starch availability but linearly decreased (P< 0.01) particle size. Decreasing flake density increased (P< 0.001) starch availability and also decreased (P< 0.001) particle size. Starch availability (P< 0.001), moisture (P< 0.001), and particle size (P= 0.05) were all greater for SFC that was collected the day of processing compared with SFC that had been processed the previous day. Steers fed diets containing SF24 consumed less DM as the moisture level increased, whereas steers fed diets containing SF28 had increased DMI as moisture level increased (moisture × FD interaction; P< 0.01). Nonetheless, ADG, G:F, and most carcass characteristics did not differ among treatments. In Exp. 2, 6 multicannulated Jersey steers were used in a 6 × 6 Latin square using the same treatments as in Exp. 1. Increasing moisture intake linearly decreased (P< 0.05) starch intakes. Organic matter and N intakes followed similar trends but were not different. Decreasing FD tended to increase (P< 0.10) microbial N flow to the duodenum and increased microbial efficiency (P< 0.05). Ruminal starch digestibility was 90.5%, and total tract starch digestibility was 99.5% without adding moisture or processing beyond SF28. Moisture additions to corn before steam flaking resulted in few differences in performance or digestibility, despite increases in starch availability that occurred as moisture increased. Processing corn more extensively than SF28 may be unnecessary and cost-prohibitive.

Three experiments were conducted to identify factors influencing steam-flaked corn (SFC) characteristics and feeding value. In Exp. 1, corn samples (n = 108) were tempered for 2 h using 6, 10, or 14% moisture containing 0 or 0.67 mL of surfactant/L. Samples were steamed for 20 or 40 min and flaked to 360, 335, or 310 g/L. Treatments were arranged in a 3 × 2 × 2 × 3 factorial. No interactions existed in Exp. 1. Increasing tempering moisture linearly (P< 0.001) increased corn moisture after tempering, steaming, and flaking; however, SFC moisture was not increased (quadratic; P< 0.001) greatly by applying more than 10% water during tempering. The surfactant, steam time, and flake density had no effect (P= 0.16 to 0.93) on corn moisture after tempering, steaming, or flaking, but adding a surfactant during tempering decreased (P= 0.05) moisture loss after flaking. Starch availability was unaffected (P= 0.31 to 0.84) by tempering moisture concentration, tempering with a surfactant, or steam time but was increased (linear; P< 0.01) by decreasing flake density. Flake durability was increased by increasing tempering moisture (linear; P< 0.001), tempering with a surfactant (P= 0.04), increasing steam time (P< 0.001), and decreasing flake density (linear; P= 0.02). In Exp. 2, 89 heifers (initial BW = 350 kg) were fed 75% SFC-based diets for 108 d to determine the effects of SFC particle size on performance and carcass traits. Treatments were SFC that was mixed for 0 (4,667 μm) or 15 min (3,330 μm) before addition of other ingredients. Heifers fed 3,330-μm SFC tended (P= 0.13) to eat less DM, but ADG and G:F did not differ (P= 0.58 to 0.65) between treatments. Carcass traits did not differ, except that heifers fed 3,330-μm SFC had less (P= 0.008) KPH. In Exp. 3, 96 heifers (initial BW = 389 kg) were fed for 82 d diets containing 73% SFC that was either 18 or 36% moisture. Heifers fed 36% moisture SFC ate less DM (P= 0.02) and gained slower (P= 0.05) than heifers fed 18% moisture SFC, but G:F did not differ (P= 0.93) with SFC moisture. Heifers fed 36% moisture SFC were fatter at the 12th rib (P= 0.009), but all other carcass traits did not differ. Methods that increase moisture of SFC improved durability, but extreme moisture levels negatively affected cattle performance. Flake particle size did not affect cattle performance. Flake density is the major factor affecting starch availability in SFC.

1. The relation between discharge frequency and angular head position was determined for a population of regularly discharging single first‐order vestibular neurones in the eighth nerve of the barbiturate anaesthetized cat.

Our objectives were to evaluate the efficacy of feeding a novel nutritional supplement providing trace minerals (CTM; zinc (Zn), manganese (Mn), and copper (Cu) as amino acid complexes and cobalt glucoheptonate compared to a supplement that provided a trace mineral profile from predominantly inorganic sources (Control; CON) on incidence and severity of digital dermatitis (DD) and related production parameters for growing-finishing feedlot heifers. Both treatments provided ethylenediamine dihydroiodide (EDDI) as a source of iodine. Analyzed values for diet samples (n=33) for CON and CTM diets, respectively, were (mg∙kg-1DM): Cu: 19 and 20; Mn: 62 and 102; Zn: 97 and 124. The study was conducted on a commercial feedlot with a history of DD. Following a 30 d starting period, 1,120 growing-finishing heifers (Initial BW = 277 kg) were randomly allotted to 8 pens (140 heifers / pen; 4 CON and 4 CTM pens). Heifers were fed the same basal diet, with ractopamine (300 mg∙hd-1∙d-1fed the last 30 d prior to slaughter. On d 189, heifers were sorted into terminal slaughter groups with total d on study being 323 (Heavier group) and 387 (Lighter group). Heifers were visually evaluated and scored for DD lesion incidence and severity using the M-stage system (M0, M2 and M4 lesions) four times throughout the study (d 70; d 148; d 189; d 248). Baseline prevalence of DD lesions was negligible and similar at initial evaluation (d 70) and increased throughout the trial with greatest prevalence observed post d 188. Feeding CTM reduced overall rate of increase for prevalence of DD lesions (active M2+chronic M4 lesions; P ≤ 0.001) compared to CON. Total weight gain for the entire trial was increased by 8 kg (P ≤ 0.09) and carcass weight increased by 5.9 kg (P ≤ 0.10) for CTM compared to CON heifers. Logistic regression analyses indicated an increase in individual animal carcass weight (HCW) of 11.8 kg (95% C.I. 5.40 – 18.7 kg) determined as a departure from overall centered mean value (HCWc) for CTM heifers compared to CON heifers. Results confirmed previous research indicating the increase in prevalence of active M2 +chronic M4 DD lesions observed with increasing days on feed was significantly mitigated in the CTM pens compared to CON pens. Providing CTM supplementation was associated with improvements in growth performance and carcass yield compared to CON pens which would provide economic benefits to feedlot management.