Biomedical subjects

M L Galyean

Publications and source records attributed to M L Galyean.

At least 37 records · Page 2Linked to original sources

PubMed2003

Prevalence of Escherichia coli O157:H7 and performance by beef feedlot cattle given Lactobacillus direct-fed microbials.

Fecal shedding of Escherichia coli O157:H7, the prevalence of Escherichia coli O157:H7 in pens and on carcasses and hides, and cattle performance as a result of daily dietary supplementation with Lactobacillus-based direct-fed microbials (DFMs) were evaluated in a feeding trial involving 180 beef steers. Steers were evaluated for shedding of E. coli O157:H7 by an immunomagnetic separation technique on arrival at the feedlot, just before treatment with the DFMs, and every 14 days thereafter until slaughter. Composite pen fecal samples were collected every 14 days (alternating weeks with animal testing), and prevalence on hides and carcasses at slaughter was also evaluated. Feedlot performance (body weight gain and feed intake) was measured for the period during which the DFMs were fed. Gain efficiency was calculated as the ratio of weight gain to feed intake. Lactobacillus acidophilus NPC 747 decreased (P < 0.01) the shedding of E. coli O157:H7 in the feces of individual cattle during the feeding period. E. coli O157:H7 was approximately twice as likely to be detected in control animal samples as in samples from animals receiving L. acidophilus NPC 747. In addition, DFM supplementation decreased (P < 0.05) the number of E. coli O157:H7-positive hide samples at harvest and the number of pens testing positive for the pathogen. Body weight gains (on a live or carcass basis) and feed intakes during the DFM supplementation period did not differ among treatments. Gain efficiencies on a live-weight basis did not differ among treatments, but carcass-based gain/feed ratios tended (P < 0.06) to be better for animals receiving the two DFM treatments than for control animals. The results of this study suggest that the feeding of a Lactobacillus-based DFM to cattle will decrease, but not eliminate, fecal shedding of E. coli O157:H7, as well as contamination on hides, without detrimental effects on performance.

Animal Feed↗

PubMed2002

Effects of supplemental vitamin E on performance, health, and humoral immune response of beef cattle.

Three experiments were conducted to examine the effect of dietary vitamin E on receiving performance and health and on finishing performance of beef cattle. One hundred twenty beef steers (Exp. 1; initial BW = 173 kg) and 200 beef heifers (Exp. 2; initial BW = 204 kg) were assigned randomly to one of three treatment diets formulated to supply 285, 570, or 1,140 IU/animal daily of supplemental vitamin E during the receiving period. Average daily gain, gain:feed, and DMI were calculated every 14 d, with pen as the experimental unit. Morbidity and retreatment data were analyzed using a nonparametric procedure. After the receiving period, cattle were assigned to a grazing period followed by a finishing program and fed until slaughter. In Exp. 3, 17 beef steers were used to evaluate effects of the same three vitamin E levels on humoral immune response to an ovalbumin vaccine given on d 0 and 14. Jugular blood samples were collected on d 0, 7, 14, and 21. In Exp. 1, vitamin E did not affect (P > 0.10) ADG, DMI, or gain:feed for d 0 to 14, 14 to 28, or 0 to 28. No effects were noted for percentage of morbidity; however, cattle receiving 1,140 IU/d had a numerically (P = 0.15) lower incidence of retreatment. During the 91-d finishing phase, a quadratic effect (P < 0.08) was noted for DMI, ADG, backfat thickness, longissimus muscle area, and yield grade. In Exp. 2, a tendency for a linear (P = 0.10) increase in ADG was observed for the first 14 d of receiving; however, ADG decreased linearly (P = 0.06) with vitamin E concentration thereafter. For the 28-d period, ADG and DMI did not differ among treatments, but gain:feed decreased linearly (P < 0.05) for d 14 to 28 and for d 0 to 28. No effects on percentage morbidity were noted in Exp. 2, and no differences were detected for ADG, gain:feed, or DMI for the 98-d finishing period. There was a linear increase in yield grade (P < 0.05) and a linear (P < 0.08) decrease in longissimus muscle area with increasing vitamin E. Heifers receiving 570 IU of vitamin E during the receiving period tended to have a higher (P < 0.09) dressing percentage at slaughter. In Exp. 3, no significant differences were detected in serum IgG titers to ovalbumin on d 0, 7 or 14; however, on d 21, a linear increase (P = 0.07) in serum IgG titers was noted with supplemental vitamin E. Supplemental vitamin E had limited effects on performance; however, effects on humoral immune response and recovery from respiratory disease warrant further research.

Age Factors↗

PubMed2002

Effect of vitamin D3 supplementation level on the postmortem tenderization of beef from steers.

The objective of this experiment was to determine the effect of different doses of vitamin D3 (VITD) on beef feedlot performance, plasma and muscle Ca2+, tissue residues, and improvement of Warner-Bratzler shear force (WBS) and panel tenderness. A total of 167 steers were fed one of six levels of VITD. The VITD treatments (28 steers/treatment) were 0, 0.5 x 10(6), 1 x 10(6), 2.5 x 10(6), 5 x 10(6), and 7.5 x 10(6) IU/steer daily of VITD fed nine consecutive days before slaughter. Feedlot performance and plasma Ca2+ were measured during the last 21 days on feed. Warner-Bratzler shear force was measured on strip loin and top round steaks at 7, 10, 14, and 21 d postmortem. The VITD treatments of 5 and 7.5 x 10(6) IU/steer daily decreased (P < 0.05) ADG, and VITD supplementation of 2.5, 5, and 7.5 x 10(6) IU/steer daily decreased average dry matter feed intake (P < 0.05) at the end of the feeding trial. Plasma Ca2+ increased linearly with VITD treatment (P < 0.01). Calpastatin and calpain activity were not influenced by treatment (P > 0.05), but muscle Ca2+ was increased (P < 0.05) by VITD treatments of 1, 2.5, 5, and 7.5 10(6) IU/steer daily. Feeding VITD did not influence (P > 0.05) carcass quality or yield traits. Supplementing VITD at levels of 1, 2.5, 5, and 7.5 10(6) IU/steer daily increased (P < 0.05) VITD concentrations in strip loin and liver samples. Cooking liver decreased VITD concentrations 10 to 28%. Vitamin D3 treatments of 0.5 and 7.5 x 10(6) IU/d reduced strip loin steak WBS at d 7 (P < 0.05), but VITD treatments did not decrease strip loin steak WBS at any other time postmortem. The VITD treatments of 0.5, 1, and 5 x 10(6) IU/steer daily decreased top round steak WBS at 7 d, and all VITD treatments decreased 10-d top round steak WBS (P < 0.05). Supplementing steers with 0.5 x 10(6) IU/steer daily of VITD also decreased (P < 0.05) top round steak WBS at 21 d postmortem compared with controls. Sensory tenderness at 7 d postmortem was increased (P < 0.05) by all VITD treatments in top round steaks, yet strip loin tenderness scores were not affected (P > 0.05) by VITD treatment. Treatment with VITD quadratically decreased (P < 0.05) round WBS. Thus, VITD treatment will effectively improve tenderness when cattle tend to be tough and have no impact on cattle that produce tender beef. Feeding steers 0.5 x 10(6) IU of VITD daily for 9 d improved tenderness in two muscles without negatively affecting feedlot performance or tissue residues.

Administration, Oral↗

PubMed2002

Effects of roughage source and concentration on intake and performance by finishing heifers.

Three experiments were conducted to evaluate the effects of roughage source and concentration on intake and performance by finishing heifers. In Exp. 1, 12 medium-framed beef heifers (average BW = 389 kg) were used in three simultaneous 4 x 4 Latin square intake trials to evaluate the effects of dietary NDF supply from alfalfa hay, sudan hay, wheat straw, or cottonseed hulls fed in each Latin square at 5, 10, or 15% of dietary DM. Within each roughage concentration, roughage NDF accounted for the majority of variation in NEg intake/kg of BW0.75 among the roughage sources. Averaged across roughage concentrations, NEg intake/kg of BW0.75 tended to be greater (P < 0.10) when heifers were fed cottonseed hulls, sudan hay, or wheat straw than when they were fed alfalfa. In Exp. 2, six medium-framed beef heifers (average BW = 273 kg) were used in a 3 x 3 Latin square design to determine whether diets containing 10% (DM basis) alfalfa, cottonseed hulls, or sudan silage differed in eating rate. Average DM eating rates did not differ (P > 0.10) among roughage sources, which we interpreted to suggest that 90% concentrate diets containing alfalfa, cottonseed hulls, and sudan silage do not differ in the amount of chewing required during eating. In Exp. 3, 105 medium-framed beef heifers (average BW = 275 kg) were used in a 140-d finishing trial to evaluate three methods of dietary roughage exchange. Alfalfa at 12.5% of the dietary DM (ALF12.5) was used as a standard, and cottonseed hulls and sudan silage were each fed at three different levels: exchanged with ALF12.5 on an equal percentage DM basis, an equal NDF basis, or an equal NDF basis, where only NDF from particles larger than 2.36 mm (retained NDF) were considered to contribute to the NDF. No differences (P > 0.10) in ADG, DMI, gain:feed ratio, or NEg intake/kg of BW0.75 were detected between alfalfa and cottonseed hulls exchanged on an equal NDF basis. For sudan silage, exchanging with ALF12.5 on an equal retained NDF basis resulted in no differences (P > 0.10) in ADG, DMI, or NEg intake/kg of BW0.75. These data provide a preliminary indication that depending on the roughage sources evaluated, roughage NDF content and(or) roughage NDF from particles larger than 2.36 mm might provide a useful index of roughage value in high-concentrate finishing diets.

Animal Feed↗

PubMed2002

Shade effects on performance, carcass traits, physiology, and behavior of heat-stressed feedlot heifers.

To determine whether shade influences performance, carcass traits, immunology, respiration rate, and behavior of cattle under conditions similar to those in commercial feedlots, we used 168 heifers in 12 soil-surfaced pens. Six pens were shaded with a galvanized steel-roofed shade (approximately 4 m high), allowing for 2.12 m2 of shade/heifer, and six pens served as the unshaded control. Heifers were fed a 90% concentrate diet during the 121-d trial that began in mid-June, performance variables (DMI, BW, ADG, gain:feed) were measured, and dietary concentrations of NEm and NEg calculated from performance data. A blood sample was collected to assess immune measures. Respiration rates and behaviors (feeding, drinking, walking, standing, lying, agonistic, and bulling) also were measured during the study. Carcass data (yield grade, kidney, pelvic, and heart fat, longissimus muscle area, hot carcass weight, quality grade, liver abscess rate, and incidence of dark-cutting beef) were collected at slaughter. Shaded heifers had higher (P < 0.05) DMI, ADG, and final BW than unshaded heifers. The gain:feed ratio and calculated dietary NEm and NEg concentrations did not differ (P > 0.26) between treatments. Most carcass traits did not differ between treatments, but more (P < 0.02) carcasses ofheifers in shaded pens graded USDA Choice than those in unshaded pens, which resulted primarily from the incidence of dark cutters being decreased (P < 0.04) by approximately half in carcasses from shaded compared with unshaded heifers. Respiration rate and percentage of circulating neutrophils were decreased (P < 0.01) for shaded compared with unshaded heifers. The treatment x time of day effect was significant (P < 0.05) for all behavioral measurements. Shaded heifers spent more time laying down (0800, 1200, and 1500, P < 0.05) and less time standing (1200 and 1500, P < 0.05) than unshaded heifers. Agonistic behavior was less (P < 0.05) for shaded than for unshaded heifers at 1900 and 2000, and bulling was less (P < 0.05) for-shaded than unshaded heifers at 2100. Results suggest that shade improved performance and altered behavior by feedlot heifers during the summertime in West Texas.

Animal Husbandry↗

PubMed2001

Effects of grain sorghum planting density and processing method on nutrient digestibility and retention by ruminants.

Grain sorghum grown in 38-cm rows (high density [HD]) or 76-cm rows (normal density [ND]) was treated as follows: steam-flaked (SF), high-moisture-harvested followed by rolling and ensiling (HM), or dry-rolled (DR). Resulting grains were evaluated using lambs in two 5 x 5 Latin square digestion trials. Treatment diets contained either SF-HD, SF-ND, HM-HD, HM-ND, or DR-ND grain sorghum in two trials; a 90 or a 60% concentrate diet was fed in each trial. High-density planting increased (P < 0.10) the apparent absorption of P relative to ND planting for both 60 and 90% concentrate diets. Steam flaking decreased (P < 0.10) the apparent absorption of P in the 90% concentrate diet and decreased (P < 0.10) the apparent absorption of N in both the 90 and 60% concentrate diets. Despite differences in N digestibility, steam flaking and HM ensiling resulted in similar (P > 0.10) N retention as a percentage of N intake in both trials. However, changes in the distribution of N between feces and urine among processing methods could affect N content of manure and alter nutrient management strategies. These results indicate that both planting density and grain processing can alter the apparent absorption of grain sorghum P by ruminants. Furthermore, it seems that grain processing can alter the route of N excretion in ruminants without changing total N retention.

Agriculture↗

PubMed2001

Shade and water misting effects on behavior, physiology, performance, and carcass traits of heat-stressed feedlot cattle.

One hundred twelve crossbred feedlot heifers were used in two experiments to assess the impact of heat stress and its relief by shade and(or) water misting on behavior, physiology, performance, and carcass traits. Treatments were 1) no shading or misting (CONT); 2) only misting (MIST); 3) only shading (SHADE); and 4) shading plus misting (SHMI). Head in the feed bunk, head in or above the waterer, walking, standing, and lying behaviors were observed. Rectal temperature, respiration rate, and carcass traits were measured, as well as DMI, ADG, and feed:gain. Dietary NEm and NEg concentrations were calculated from performance data. In Exp. 1, (32 heifers; average BW 288 kg) the CONT heifers spent more time lying down than all others (P < 0.01). In addition, CONT heifers spent less time (P < 0.01) standing than SHADE and MIST heifers. Misting decreased (P < 0.01) rectal temperature and MIST as well as SHADE lowered (P < 0.05) respiration rates. In Exp. 2 (80 heifers; average BW = 336 kg), lying and walking behaviors did not differ among treatments, but shade increased (P < 0.01) standing behavior in heifers. The MIST cattle performed less (P < 0.05) head-above-water behavior than unmisted cattle. Rectal temperatures did not differ among treatments, but respiration rate was lower in shaded than in unshaded heifers (P < 0.05). Shaded compared with unshaded heifers had greater DMI (9.46 vs 8.80 +/- 0.14 kg/d, P < 0.01) and ADG (1.6 vs 1.41 +/- 0.1 kg/d, P < 0.01). Heifers provided with shade reached their target BW 20 d earlier than the unshaded heifers and differed in final BW (547 vs 520 +/- 6 kg, P < 0.01). Feed:gain and calculated NEg and NEm concentrations did not differ among treatments, and carcass traits were generally similar among treatments. In conclusion, cattle without shade had a physiological and behavioral stress response to heat that negatively affected productivity. Providing shade for beef cattle was a suitable solution to decrease heat stress and to lower the negative effects of heat on performance, whereas misting was largely ineffective.

Animal Husbandry↗

PubMed2000

Association between changes in eating and drinking behaviors and respiratory tract disease in newly arrived calves at a feedlot.

OBJECTIVE: To investigate eating and drinking behaviors and their association with bovine respiratory disease complex (BRDC) and to evaluate methods of diagnosing BRDC. ANIMALS: 170 newly arrived calves at a feedlot. PROCEDURE: Eating and drinking behaviors of calves were recorded at a feedlot. Calves with clinical signs of BRDC were removed from their pen and classified retrospectively as sick or not sick on the basis of results of physical and hematologic examinations. Pulmonary lesions of all calves were assessed at slaughter. RESULTS: Calves that were sick had significantly greater frequency and duration of drinking 4 to 5 days after arrival than calves that were not sick. Sick calves had significantly lower frequency and duration of eating and drinking 11 to 27 days after arrival but had significantly greater frequency of eating 28 to 57 days after arrival than calves that were not sick. Calves at slaughter that had a higher percentage of lung tissue with pneumonic lesions had significantly lower frequency and duration of eating 11 to 27 days after arrival but had significantly higher frequency and duration of eating 28 to 57 days after arrival. Agreement for calves being sick and having severe pulmonary lesions at slaughter was adequate. Agreement for calves being removed and having pulmonary lesions at slaughter was low. CONCLUSIONS AND CLINICAL RELEVANCE: Eating and drinking behaviors were associated with signs of BRDC, but there was not an obvious predictive association between signs of BRDC in calves and eating and drinking behaviors. Fair to poor agreement was observed between antemortem and postmortem disease classification.

Animal Husbandry↗

PubMed2000

Lesions and effects of location for administration of clostridial bacterin-toxoid vaccines on growth performance and eating and drinking behaviors in newly arrived calves at a feedlot.

OBJECTIVES: To determine the effect of location for administration of clostridial vaccines on behavior, growth performance, and health of calves at a feedlot, the relative risk of calves developing an injection-site reaction or being misdiagnosed as having bovine respiratory disease complex (BRDC), and the percentage of subcutaneous injection-site reactions that were detectable on carcasses after the hides were removed. ANIMAL: 170 newly arrived calves at a feedlot. PROCEDURE: Eating and drinking behaviors of calves during the initial 57 days after arrival were observed at a commercial feedlot, using an electronic monitoring system. Calves were assigned randomly to receive a clostridial vaccine (base of ear or neck). Data on reactions at the injection site were collected. RESULTS: Mean daily gain (MDG) for the initial 57 days did not differ significantly between treatments. Risk of being misdiagnosed as having BRDC was not associated with location for administration of vaccine. Calves vaccinated in the base of the ear were at higher risk of having an injection-site reaction at day 57 or at slaughter. Eighty-nine percent (95% confidence interval, 52 to 100%) of injection-site reactions in the neck could not be located on the carcasses after hides were removed. Calves vaccinated in the neck drank significantly fewer times per day during the first 57 days than calves vaccinated in the base of the ear. CONCLUSIONS AND CLINICAL RELEVANCE: Location for administration of a clostridial vaccine did not significantly affect health, growth performance, or eating behavior. Most subcutaneous injection-site reactions were not detectable after the hide was removed.

Animal Husbandry↗

PubMed2000

Evaluation of models of acute and subacute acidosis on dry matter intake, ruminal fermentation, blood chemistry, and endocrine profiles of beef steers.

Crossbred steers (n = 20; 316 +/- 4 kg BW), each fitted with a ruminal cannula, were used to evaluate the effects of acute acidosis (AA) and subacute acidosis (SA) on DMI, ruminal fermentation, blood chemistry, and endocrine profiles. Animals were blocked by BW and assigned to treatments including 1) intraruminal (via cannula) steam-flaked corn (3% of BW; AA); 2) intraruminal dry-rolled wheat:dry-rolled corn (50:50; 1.5% of BW; SA); 3) offering forage-adapted steers ad libitum access to a 50% concentrate diet (AA control; AC); and 4) offering 50% concentrate diet-adapted steers ad libitum access to a 50% concentrate diet (SA control; SC). Samples of ruminal fluid and whole blood were collected on the day of the challenge (d 0) and 3, 7, 10, and 14 d after the challenge. Daily DMI responded quadratically (P < 0.01) through d 7 for AA and SA steers and increased linearly (P < 0.01) for AC steers. Dry matter intake by AA steers reached a nadir (< 3 kg/d) on d 3 and gradually increased to a level similar to other treatments (7 kg/d) by d 10, whereas DMI by SA steers increased through d 3. Blood pH, bicarbonate, base excess, and total CO2 were decreased (P < 0.03) for AA steers and increased (P < 0.03) for SC steers through d 7. Ruminal pH decreased quadratically (P < 0.01) in AA and AC steers and increased (P = 0.01) in SA steers through d 7. Ruminal total lactate concentration and osmolality responded quadratically (P < 0.01) for AA and AC steers. Ruminal total lactate peaked on d 3 for AA steers and on d 0 for AC and decreased to basal concentrations by d 7. Plasma NEFA concentration increased (P < 0.04) on d 3 and 7 for AA steers. Serum Na decreased (P < 0.05) on d 0 for AA and SA steers and on d 7 and 14 for AA steers. Serum P decreased (P = 0.01) for AA steers through d 7 and decreased quadratically (P = 0.01) for AC steers through d 7. Serum albumin and cholesterol decreased (P < 0.02) for AA and AC steers through d 7. Area under the GH curve decreased (P = 0.02) for AA and AC steers through d 7. Considerable variation was evident in the ability of an animal to cope with a carbohydrate challenge. Results of data modeling generally suggest that serum amylase activity, cholesterol and potassium concentrations, and plasma NEFA concentrations were useful in distinguishing between steers classified as experiencing subacute acidosis or not affected by a carbohydrate challenge.

Acidosis↗

PubMed2000

Effects of planting density and processing method on laboratory characteristics of grain sorghum for ruminants.

Grain sorghum grown in 38-cm (high-density) or 76-cm rows (normal-density) was steam-flaked, harvested as high-moisture grain followed by rolling and ensiling, or dry-rolled. Chemical composition, enzymatic starch availability, CP insolubility, and IVDMD in a reduced-strength buffer were evaluated. High-density planting increased (P < .10) OM and starch concentration and decreased (P < .0001) CP concentration but did not affect (P > .10) P concentration, enzymatic starch availability, or CP insolubility. High-density planting resulted in lower (P < .10) in vitro ruminal culture pH at 6, 12, and 18 h of incubation when grain sorghum was processed by steam flaking, and lower (P < .10) IVDMD at 6, 12, and 18 h of digestion when grain sorghum was processed by dry rolling. Steam flaking decreased (P < .10) CP concentration and solubility and increased (P < .10) OM concentration. High-moisture ensiling decreased (P < .10) the insolubility of CP but did not otherwise seem to alter the chemical composition of grain sorghum relative to dry rolling. Starch was more available (P < .10), and DM was digested more rapidly and extensively (P < .10) in vitro, in steam-flaked sorghum followed by high-moisture sorghum. Based on these data, it seems that planting density primarily affected chemical composition of grain sorghum, whereas processing primarily affected CP insolubility and rate and extent of starch fermentation.

Agriculture↗

PubMed2000

Influence of feed intake fluctuation and frequency of feeding on nutrient digestion, digesta kinetics, and ruminal fermentation profiles in limit-fed steers.

Nine crossbred beef steers (344 +/- 26 kg) fitted with ruminal cannulas were used in a randomized complete block design to evaluate the effects of feeding frequency and feed intake fluctuation on total tract digestion, digesta kinetics, and ruminal fermentation profiles in limit-fed steers. In Period 1, steers were allotted randomly to one of four dietary treatments: 1) feed offered once daily at 0800; 2) feed offered once daily at 0800 with a 10% fluctuation in day-to-day feed intake; 3) feed offered twice daily at 0800 and 1700; and 4) feed offered twice daily at 0800 and 1700 with a 10% fluctuation in a day-to-day feed intake. In Period 2, steers were reallocated across treatments. The 90% concentrate diet was fed at 90% of the ad-libitum consumption by each steer. Chromium-EDTA and Yb-labeled steam-flaked corn were intraruminally infused at 0800 on d 1 and 3 and Co-EDTA and Er-labeled steam-flaked corn were infused on d 2 and 4 of the 4-d collection period. Ruminal samples were collected at 0, 3, 6, 9, 12, 15, 18, and 24 h after the 0800 feeding, and total feces were collected for 4 d. Total tract digestibilities of OM, N, and starch were lowest (fluctuation x frequency, P < .05) when feed was offered twice daily with a 10% fluctuation in intake. Ruminal fluid volume and passage rate were not affected (P > .10) by feeding frequency or intake fluctuation. A frequency x fluctuation x sampling time interaction occurred (P < .01) for ruminal pH. Steers fed a constant amount of feed once daily had higher (P < .05) ruminal pH at 0, 3, 18, and 24 h than steers fed once daily with a 10% fluctuation in feed intake. Total VFA concentration was greater (P < .01) at 9 h after the 0800 feeding when feed was offered once vs twice daily. Feeding twice daily increased (P < .05) the molar proportion of acetate and decreased (P < .05) the molar proportion of propionate. Increasing feeding frequency resulted in a more stable ruminal environment; however, the increased acetate:propionate ratio with twice-daily feeding might result in lower efficiency of energy utilization by limit-fed steers.

Animal Feed↗

PubMed2000

Effect of degree of corn processing on urinary nitrogen composition, serum metabolite and insulin profiles, and performance by finishing steers.

Two experiments were conducted to determine the effect of degree of corn processing on urinary ammonia and urea N concentrations, serum metabolite and insulin concentrations, and feedlot performance of steers. Corn was processed by either dry rolling to .54 kg/L bulk density (DR42; 42 lb/bushel) or steam flaking to a bulk density of .36 or .26 kg/L (28 [SF28] and 20 [SF20] lb/bushel, respectively). Degrees of processing were selected to generate final products with 25, 50, or 75% enzymatically available starch. Available starch, expressed as a percentage of total starch for DR42, SF28, and SF20, averaged 24.5, 56.4, and 81.1% in Exp. 1 and 22.4, 60.1, and 80.1% in Exp. 2. In Exp. 1, 29 steers were housed in individual outdoor pens and adapted to a 90% concentrate diet over 21 d. Whole blood and urine were collected before feeding and at 4 and 8 h after feeding on d 0, 7, 14, 21, 28, 84, and 140. Daily DMI decreased linearly (P < .03) as degree of processing increased, whereas water intake did not differ (P > .42) among treatments. Average daily gain, ADG:DMI, and hot carcass weight responded quadratically (P < .04) to an increasing degree of processing. Urinary ammonia and urea N concentrations were not influenced (P > .30) by degree of processing. Whole blood packed cell volume, serum glucose, creatinine, D(-)-lactate, L(+)-lactate, and lactate dehydrogenase activity did not differ (P > .15) among treatments. For insulin data, ME intake on the day of sample collection was evaluated as a covariate. On d 28, serum insulin (2.49, 2.95, and 1.80+/-.33 ng/mL) responded quadratically (P = .04) as degree of processing increased. Serum insulin did not differ (P = .52) on d 84, whereas insulin (5.77, 7.51, and 4.12+/-.98 ng/mL) responded quadratically (P = .02) on d 140. In Exp. 2,216 steers were blocked by BW into two blocks (18 pens; 12 steers/pen) and assigned to the same treatments used in Exp. 1. Daily DMI and carcass weight responded quadratically (P < .05), whereas ADG and ADG:DMI increased linearly (P < .04) with increasing degree of processing. Results suggest that the degree of corn processing influences serum insulin concentrations of feedlot steers; however, serum metabolites, urinary nitrogen composition, and carcass characteristics were generally not affected by degree of corn processing.

Animal Feed↗

PubMed1999

Effects of dietary level of ruminally protected choline on performance and carcass characteristics of finishing beef steers and on growth and serum metabolites in lambs.

Ruminally protected choline (RPC) was evaluated in two experiments. In Exp. 1, beef steers (n = 160; average initial BW = 350.9 kg) were fed a 90% concentrate diet with either 0, .25, .5, or 1.0% RPC (DM basis) for 112 to 140 d. Feeding .25% RPC increased ADG 11.6% compared with 0% RPC, but responses diminished with increasing RPC level (cubic response, P < .10). Daily DMI was not affected by RPC level, but feed:gain was improved 6.8% with .25% RPC compared with 0% RPC, and responses diminished with increasing RPC level (cubic response, P < .10). Carcass yield grade increased linearly (P < .10) as RPC level increased, but marbling score was lower for all three RPC-containing diets than for the 0% RPC diet (quadratic response, P < .05). In Exp. 2, 20 Suffolk lambs (initial BW = 29.8 kg) were fed an 80% concentrate diet for 56 d with the same RPC levels as in Exp. 1. Serum triglycerides (TG) and cholesterol (CLSTRL) were measured in weekly blood samples, and intensive blood samples were collected on d 28 and 56 to evaluate serum insulin (INS), GH, and NEFA. For the 56-d feeding period, ADG responded quadratically (P < .10) to RPC level, but DMI and feed:gain were not affected. Serum INS and NEFA concentrations increased linearly (P < .05) and serum GH responded cubically (P < .05) to RPC level on d 28, but no differences were noted on d 56. Serum TG concentrations in weekly samples increased linearly (P < .10) with RPC level, but, averaged over all weeks, serum CLSTRL concentrations did not differ (P > .10) among treatments. Quantities of carcass mesenteric (P < .05) and kidney fat (P < .10) increased linearly, but longissimus muscle and liver fat contents did not differ (P > .10) among RPC levels. Supplementing RPC in high-concentrate diets improved performance, but results were not consistent among RPC levels or between cattle and sheep. Potential effects of RPC might be mediated through alterations in fat metabolism and(or) metabolic hormones related to fat metabolism.

Animal Feed↗

PubMed1999

Effect of ruminal glucose infusion on dry matter intake, urinary nitrogen composition, and serum metabolite and hormone profiles in Ewes.

Twelve 18-mo-old Debouillet ewes were used to determine the effect of ruminal glucose infusion on DMI, on urinary ammonium (NH4+) and urea N (UUN) concentrations, and on serum metabolite and hormone profiles. Ewes were limit-fed a 90% concentrate diet for 30 d, stratified by BW into three groups (average BW = 82.6+/-1.1 kg), and assigned randomly to receive 0, 5, or 10 g of glucose/kg of BW via esophageal intubation. Urine was collected hourly for 12 h and blood (jugular venipuncture) at 30-min intervals for 12 h. After 12 h, ewes were housed individually, allowed free access to the diet, and DMI was recorded for 5 d. Venous blood pH averaged 7.49, 7.48, and 7.48 at 0 h and decreased (linear [L], P < .01) at 12 h (7.41, 7.36, and 7.26) with increasing glucose. Serum glucose increased (L, P = .06) at 3 and 6 h. Serum L(+)-lactate increased (L, P = .08) at 3, 6, and 9 h, whereas serum D(-)-lactate increased linearly (P = .09) at 6 and 9 h and quadratically (P < .10) at 12 h. After the glucose challenge, DMI decreased (L, P < .05). Urinary pH and NH4+ were not influenced by glucose infusion; however, UUN increased at 3 (quadratic [Q], P < .05), 4, 5, 6 (L, P = .03), and 7 h (Q, P < .05) and decreased at 11 and 12 h (L, P = .09). As glucose infusion increased, serum creatinine increased at 9 (L, P < .01) and 12 h (Q, P = .02). Generally, serum Na and P increased (P = .09), whereas K decreased (P < .05), with glucose infusion. Lactate dehydrogenase activity increased with glucose infusion (Q, P < .10) at 3, 6, 9, and 12 h. Increasing glucose infusion increased serum globulin (Q, P = .06), albumin, and total protein (L, P = .08). Serum prolactin and vasopressin were not influenced (P = .22) by glucose infusion. Serum insulin and aldosterone increased quadratically (P = .08), whereas serum growth hormone decreased linearly (P = .08) as a result of increasing glucose infusion. Results suggest that UUN, serum insulin, aldosterone, and several serum constituents may serve as markers of organic acid load in ruminants fed high-concentrate diets.

Acidosis, Lactic↗

PubMed1999

Interaction of cattle health/immunity and nutrition.

The usual means of assessing the health of newly received beef cattle susceptible to bovine respiratory disease (BRD) are subjective, typically involving visual evaluation aided by minimal clinical measurements. Recent evidence based on the occurrence of pneumonic lung lesions at slaughter indicates a need for more accurate methods of diagnosing BRD. Inadequate passive immune transfer at birth may be an important risk factor in susceptibility to BRD, suggesting the need for management to improve passive transfer success rates. Preweaning management and vaccination practices offer opportunities for beef cattle producers to improve the immune status of newly weaned calves and decrease postweaning BRD. Feeding diets with higher levels of concentrate typically improves performance by newly weaned or received cattle, as does feeding diets supplemented with protein; however, limited data suggest that increasing concentrate and protein in receiving diets increases the rate and severity of subjectively determined BRD morbidity. Research with receiving diet concentrate/protein level relative to humoral and cell-mediated immune function coupled with indicators of health and performance is needed. Supplemental B vitamins are sometimes useful in receiving diets, but the effects have been variable, presumably reflecting differences in stress and associated feed intake responses. Vitamin E added to receiving diets to supply > or = 400 IU/animal daily seems beneficial for increasing gain and decreasing BRD morbidity; however, further dose titration experiments are needed. Supplemental Zn, Cu, Se, and Cr can alter immune function of newly received calves, and some field trials have shown decreases in BRD morbidity rate with supplementation; however, several experiments have shown no performance or health/immune benefits from supplementation of these trace minerals. Formulation of receiving diets should take into account decreased feed intake by highly stressed, newly received beef cattle and known nutrient deficiencies, but fortification of such diets with trace minerals beyond the levels needed to compensate for these effects is difficult to justify from present data.

Animal Nutritional Physiological Phenomena↗

PubMed1998

Nutrition and disease.

Mortality from digestive diseases in feedlot cattle is second only to that from respiratory diseases. Acidosis and bloat are the major digestive disorders and are likely to continue because of ongoing attempts to improve the efficiency of beef production by feeding more grain and less roughage. Subacute acidosis is probably the most prevalent form of acidosis in feedlots and is difficult to diagnose because of the absence of overt clinical signs. Ruminal changes in subacute acidosis are not as dramatic as those in acute acidosis. Also, the subacute form is not severe enough to induce systemic acidosis. Ruminal acidosis is also a predisposing factor for many other ailments in feedlot cattle such as laminitis, polioencephalomalacia, sudden death syndrome, and liver abscesses. Control of acidosis is achieved largely by sound nutritional management. Antimicrobial compounds (i.e., ionophores and nonionophores), have become management tools to impart stability to ruminal fermentation, modulate feed intake, and control acidosis. Bloat in feedlot cattle can be of free gas or frothy type. Frothy bloat is more common but is rarely the reason for bloat deaths. The economic impact of bloat results mainly from decreased animal performance. The etiology of bloat is complex and is the result of interactions between three major groups of factors: animal, dietary, and microbial. Presently, an effective method to control frothy bloat in feedlot cattle is not available. Ionophore antibiotics, particularly monensin, have been shown to be effective in decreasing the incidence and severity of bloat in cattle.

Acidosis↗

PubMed1998

Application of research findings and summary of research needs: Bud Britton Memorial Symposium on Metabolic Disorders of Feedlot Cattle.

Updated research findings with acidosis, feedlot bloat, liver abscesses, and sudden death syndromes were presented at the Bud Britton Memorial Symposium on Metabolic Disorders of Feedlot Cattle. Possible industry applications include the need to establish guidelines for use of clostridial vaccines in feedlot cattle, further assessment of the relationship between acidosis and polioencephalomalacia, examination of the effects of various ionophores on the incidence of metabolic disorders, and evaluation of the effects of feed bunk management and limit- and restricted-feeding programs on the incidence of metabolic disorders. A multidisciplinary approach among researchers, consulting nutritionists and veterinarians, and feedlot managers will be required for effective progress in research and in the application of research findings. Areas suggested for further research include 1) assessment of feed consumption patterns and social behavior of cattle in large-pen, feedlot settings; 2) evaluation of the relationship between feed intake management systems (feed bunk management programs, limit- and programmed-feeding) and the incidence of metabolic disorders, including delineation of the role of variability in feed intake in the etiology of such disorders; 3) efforts to improve antemortem and postmortem diagnosis, and to establish standardized regional or national epidemiological databases for various metabolic disorders; 4) ascertaining the accuracy of diagnosis of metabolic disorders and determining the relationship of previous health history of animals to the incidence of metabolic disorders; 5) further defining ruminal and intestinal microbiology as it relates to metabolic disorders and deeper evaluation of metabolic changes that occur with such disorders; 6) continued appraisal of the effects of grain processing and specific feed ingredients and nutrients on metabolic disorders, and development of new feed additives to control or prevent these disorders; and 7) application of biotechnology to develop grain varieties with altered nutrient degradation profiles that decrease the propensity for disastrous acid loads in the rumen, feed-grade enzymes and probiotics that modify nutrient digestion or microbial profiles in the rumen and intestine, and specific strains of ruminal bacteria and protozoa that alter ruminal and metabolic conditions that may precipitate metabolic disorders.

Acidosis↗