Dimethylhydrazine-induced colon tumors in rats fed diets containing beef fat or corn oil with and without wheat bran.

Male rats of the Sprague-Dawley strain were fed semisynthetic diets containing either 20% beef fat or corn oil with and without 20% wheat bran. Half of the animals received four weekly doses and the other half received eight weekly doses of dimethylhydrazine, 30 mg/kg, by intragastric intubation. The percentage of rats with tumors of the colon of all types was significantly higher in animals fed no bran than in those fed bran. Likewise, the percentage of rats with polypoid neoplasms of the colon was higher in rats fed no bran, but there was no significant difference in the percentage of rats with malignant tumors of the colon with respect to the feeding of bran. No significant differences were found between rats fed corn oil and those fed beef fat with respect to either the incidence or the kinds of colon tumors. Malignant tumors of the colon, causing death, occurred earlier in rats fed corn oil as compared to those fed beef fat. The percentage of rats with tumors of the colon and the numbers of tumors per tumor-bearing rat were significantly increased in rats given eight doses of dimethylhydrazine or compared to those given four.

Natural human interferon-alpha administered orally as a treatment of bovine respiratory disease complex.

Natural human interferon-alpha (nHuIFN-alpha) from three sources was given orally to 368 calves experiencing a natural outbreak of bovine respiratory disease complex (BRDC). In one study, 200 calves were given one treatment daily for 3 days of placebo or 20, 200, or 2,000 IU of nHuIFN-alpha before shipment. Calves treated with 20 or 200 IU had a significant (p < 0.05) weight gain benefit for the first 21 days in the feedlot, if they had rectal temperatures <40 degrees C when treated with nHuIFN-alpha. In a second trial, 168 mixed-breed calves (five groups randomized to 31-36 calves/group) were treated with one dose of placebo or 200 or 400 IU of nHuIFN-alpha after shipment to the feedlot. Using this regimen, a dose of 200 IU per calf significantly (p < 0.08) decreased the number of sick calves per group and delayed development of BRDC. Results of these studies demonstrate that oral administration of nHuIFN-alpha, which may partially mimic the nasally secreted IFN response reported during BRDC, may be beneficial in cattle.

Oral therapy with human interferon alpha in calves experimentally injected with infectious bovine rhinotracheitis virus.

Fifty-six calves, seronegative for infectious bovine rhinotracheitis (IBR) virus, were randomly divided into 7 equal groups (n = 8) and given 0.0, 0.05, 0.50, or 5.00 international units (IU) of natural or recombinant human interferon alpha per kg body weight (nHuIFN-alpha or rHuIFN-alpha, respectively) orally once daily for 4 consecutive days, starting 2 days before intranasal inoculation with virulent IBR virus. Calves given 0.05 IU nHuIFN-alpha/kg bwt had significantly greater weight gain at days 15 (P < 0.10) and 25 (P < 0.05) than the placebo-treated (0.0 IU) control group. The treatment groups given 0.05 and 0.5 IU nHuIFN-alpha/kg bwt nHuIFN-alpha had fewer days with temperature > 40 degrees C (P < 0.05 and P = 0.10, respectively), and lower mean rectal temperatures on days 8 and 11 (0.05 IU/kg bwt; P < 0.10) or on day 11 (0.5 IU/kg bwt; P < 0.10). None of the calves given 0.05 IU nHuIFN-alpha/kg bwt required antibiotic therapy. Calves given 0.50 IU/kg bwt of nHuIFN-alpha, or 0.05 IU/kg bwt of rHuIFN-alpha had fewer (P < 0.05) total days of antibiotic therapy compared to controls. These data indicate that low dose oral IFN-alpha treatment significantly reduced the clinical effects of IBR virus infection in feedlot cattle in an interferon dose-dependent fashion.

The effect of low dose oral human interferon alpha therapy on diarrhea in veal calves.

Low doses of recombinant human interferon alfa 2a (rHuIFN-alpha 2a), were given orally in milk replacer formula to veal calves to determine the efficacy of rHuIFN-alpha 2a for protection against diarrhea, ear and/or respiratory tract infections common in vealing operations. Calves given rHuIFN-alpha 2a had fewer days and a lower incidence of diarrhea, compared to placebo-treated calves. Calves treated with rHuIFN-alpha 2a had significantly (P < 0.05) fewer ear infections and fewer total days of ear infection than did placebo-treated calves. The mortality rate was lower in the rHuIFN-alpha 2a treatment group (1.6%) than in the placebo treatment group (2.9%) and calves given rHuIFN-alpha 2a had a greater average weight gain (13.1 lbs. more per calf) than calves given placebo. These data demonstrate that orally administered rHuIFN-alpha 2a exhibited a protective effect against clinically significant signs of disease in veal calves, reduced the mortality rate in this population, and enhanced average weight gain.

The use of interferon modulates the negative effects of heat stress on poultry production.

A trial was conducted with broilers reared in two temperature environments; one was thermoneutral and the other had cycling ambient temperatures. Human interferon alpha (HuIFN-alpha) was added to the drinking water daily at four dose levels (0.0, 0.01, 0.1 and 1.0 international units (IU) per ml of drinking water). The trial began with 21 day old chicks housed either in a thermoneutral (24 degrees C) or a cycling ambient temperature (24-36 degrees C) environment. Interferon added to water at the highest concentration (1.0 IU/ml) improved surviability of birds in the cycling ambient temperature (24-36 degrees C) environment (P < 0.05). Birds housed in the cycling (24-36 degrees C) environment, drinking the lowest concentration of IFN-alpha 0.01 IU/ml, had a significantly improved weight gain-to-feed ratio. Oral IFN-alpha reduced the cost of production for birds reared in a cycling ambient temperature environment.

Oral treatment of transmissible gastroenteritis with natural human interferon alpha: a field study.

During a natural outbreak of transmissible gastroenteritis (TGE), groups of piglets were treated orally for 4 consecutive days with placebo or 1.0, 10.0 or 20.0 international units (IU) natural human interferon alpha (nHuIFN alpha). Piglets that were 1-12 days of age and given 1.0, 10.0 or 20.0 IU nHuIFN alpha had significantly (P < 0.01) greater survival rates than placebo-treated piglets; survival rates were the greater for the highest level of nHuIFN alpha treatment. In contrast, beneficial effects of nHuIFN alpha were not observed in piglets farrowed during the disease outbreak and given nHuIFN alpha within hours of birth. Oral nHuIFN alpha therapy modulates the natural course of high morbidity and mortality commonly seen with TGE.

Physiochemical properties of oviductal fluid from rabbits exposed to heat stress.

Oviductal fluids (OF) were collected at 24 hour intervals from 27 does. Fluids were collected from all does during estrus and subsequent pregnancy or pseudopregnancy. After collecting OF for 15 days from all does maintained at 21 degrees C and 45% relative humidity (RH), approximately one-half of the does were then subjected to heat stress (33.20+/-0.75 degrees C and 65.4+/-2.3% RH). Oviductal fluid was then collected for 5 days from heat stressed estrous does (HSER), after which all does (both control and HSER) were mated to fertile bucks. Human chorionic gonadotropin was administered to each doe to insure ovulation. Fluids were compared between HSER and heat stressed pregnant rabbits (HSPR) and control estrous (NHER) and pregnant rabbits (NHPR) for volume, pH, various protein concentrations, and total protein content. Fluid volume decreased due both to heat stress and pregnancy. Heat stress increased pH, whereas pregnancy resulted in a decrease. Protein concentration of OF from HSER declined due to heat stress. Protein concentration of OF from NHPR increased prior to breeding, peaking at day 3 of pregnancy, then declined to initial levels. While from HSPR there was also a tendency to have a similar increase, the peak in protein concentration was on day 4 and then decreased on day 5. Total protein content (concentration x volume) of OF from HSER decreased due to heat stress. Total protein content from HSPR and NHPR had similar changes with or without heat stress, although the total protein content from OF of HSPR was less (except for day 3) for the entire 5 day period studied. Relative percentages of albumin decreased and postalbumin increased during the first day of pregnancy (NHPR). These trends were reversed (a relative increase in albumin and a decrease in postalbumin) in OF from HSPR.

Ultrasonic measurement of arterial blood pressure in conditioned thoroughbreds.

Indirect systolic and diastolic arterial pressure measurements of 456 Thoroughbred horses of various ages and sex stabled at 9 different race tracks were measured with an ultrasonic-Doppler device interfaced with a sphygmomanometer cuff. The mean systolic pressure was 111.8 +/- 13.3 mmHg and the mean diastolic pressure was 69.6 +/- 13.8 mmHg in this population.

Recovery from anaesthesia in ponies: a comparative study of the effects of isoflurane, enflurane, methoxyflurane and halothane.

The duration and quality of recovery after separate 2 hour anaesthetic periods with equipotent alveolar concentrations of isoflurane, enflurane, halothane and methoxyflurane were evaluated in experimental ponies. Recovery was shortest after isoflurane anaesthesia, followed by enflurane, halothane and finally methoxyflurane, although standing was achieved more rapidly after enflurane than after isoflurane. This sequence of recovery times was compatible with the respective solubilities of the 4 agents. The smoothest recovery was obtained after isoflurane anaesthesia, followed by methoxyflurane, halothane and then enflurane. The isoflurane recovery was characterized by very quiet and prolonged sternal recumbency with excellent coordination upon standing. The chief difficulties with halothane recovery were shivering and delayed coordination upon standing. Enflurane anaesthesia was followed by a very brief period of sternal recumbency but there was considerable shivering and incoordination upon standing. This may have been due to central nervous stimulation during anaesthesia producing a residual excitatory effect. On the basis of this investigation, isoflurane was considered to be the most satisfactory volatile anaesthetic for the horse.

Changes in the caecal flora associated with the onset of laminitis.

Caecal fluid samples collected 8 and 24 hours after carbohydrate overload were quantitatively compared to control samples in terms of aerobic and anaerobic bacteria. Concomitant increases in lactic acid-producing bacteria and decreases in Gram negative bacteria were substantiated during the onset of acute laminitis. Progressive decreases in caecal fluid pH were also quantitated. Although endotoxin assays of caecal fluid and blood were not done, the caecal flora changes suggest its presence during the onset of acute laminitis.

Influence of protein concentration in prefast and postfast diets on feed intake of steers and nitrogen and phosphorus metabolism of lambs.

Two trials were conducted to determine the influence of prefast and postfast dietary protein concentration on feed intake of steers (avg wt 250 kg) and the N and P metabolism of lambs (avg wt 50 kg). In Trial 1, crossbred steers were fed prefast diets containing 8, 12 or 16% crude protein (CP) for 14 d before being deprived of feed and water for 24 h. Next, they received feed for 24 h and again were deprived for 48 h. Finally, they were fed diets containing either 10 or 15% CP. Steers fed the 16% CP prefast diet that were switched to the 10% CP realimentation diet tended to have lower feed intakes than the other fasted groups. In Trial 2, 16 crossbred lambs housed in metabolism stalls were fed prefast and postfast diets containing either 11 or 16% CP both before and after a 72-h fast in a 2 x 2 factorial arrangement. Nitrogen and P balance during realimentation tended to be affected by both the prefast and postfast dietary protein concentration. Results of this study indicate that CP content of the postfast diet alters repletion of nutrients lost during a feed and water deprivation period and can affect realimentation feed intake. However, the magnitude of this effect was dependent on protein content of the prefast diet.

Influence of pre-fast dietary roughage content on recovery from feed and water deprivation in beef steers.

Sixty steer calves of mixed British breeding averaging 268 kg were randomly assigned to four treatment groups of 15 calves each to determine the influence of pre-fast dietary roughage content on recovery from feed and water deprivation. Three groups were fed diets containing either 84 (HR), 60 (MR) or 35% (LR) roughage at 1.75% of body weight for 3 d. Calves in these three groups were deprived of feed and water for 24 h, limit-refed and watered for 24 h, and deprived of feed and water for 48 h (deprivation). Calves were then fed the MR diet ad libitum for 2 wk. The fourth group of control steers was continuously fed the MR diet throughout the experiment. Realimentation weight gains and feed intakes were not affected by pre-fast diet roughage content. Blood packed cell volume increased (P less than .05) during deprivation. Blood potassium was not affected by deprivation but declined (P less than .05) upon refeeding. Plasma urea-N increased (P less than .05) during deprivation but returned to pre-fast concentrations by d 3 of realimentation. Ruminal volume was not significantly affected by deprivation but increased (P less than .05) by 50 to 100% upon refeeding. Ruminal fluid total volatile fatty acid (VFA) concentrations declined (P less than .05) during deprivation. On d 3 of realimentation, a linear contrast (P less than .05) was observed between total VFA concentrations and the pre-fast diet roughage content.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of dietary protein concentrations on performance and nitrogen repletion in stressed calves.

Three trials were conducted to determine the influence of dietary CP concentration on health and performance of market-transport-stressed feeder calves (Exp. 1 and 2) and on repletion of nutrients lost during a 3-d feed and water deprivation period in steers fed at maintenance energy intake (Exp. 3). In Exp. 1 (84 calves) and 2 (256 calves), feeder calves averaging 184 kg were transported from Tennessee to Texas. In Exp. 1, calves were fed receiving diets containing either 12 or 16% CP. In Exp. 2, calves were fed diets containing 12 or 16% CP and .8 or 1.3% potassium in a 2 x 2 factorial arrangement of treatments. In Exp. 3, four Hereford steers averaging 253 kg were used in an N balance trial. Steers were deprived of feed and water for 3 d and then were limit-fed (1 x maintenance energy requirements) diets calculated to meet 100, 120, 140 or 160% of CP maintenance requirements for 14 d in a 4 x 4 Latin square design. In Exp. 1, calves fed the 16% CP diet had faster (P less than .05) daily gains and higher (P less than .10) feed consumption than calves fed the 12% CP diet during the first 14 d. In Exp. 2, calf performance was not affected by diet CP or K content. Calves fed the 16CP-1.3K diet had lower (P less than .10) mortality than calves on the remaining treatments. In Exp. 3, N balance and serum urea N increased linearly (P less than .05) with increasing dietary CP. Results of these studies are interpreted to indicate that the CP requirement (g/d) of market-transport-stressed feeder calves is similar to requirements of nonstressed calves; however, the CP concentration of the diet of stressed calves may need to be increased when feed intakes are low.

Influence of realimentation diet on recovery of rumen activity and feed intake in beef steers.

Two trials were conducted to determine the influence of realimentation diet energy, protein, B-vitamin (BV) and Lactobacillus acidophilus (LAC) content on recovery of rumen activity and feed consumption in beef steers. In trial 1, ruminal-fistulated steers were fasted and refed 1) prairie hay, 2) 10% protein (LCP), 3) 12.5% protein (MCP), 4) LCP + BV or 5) LCP + LAC. In trial 2, calves were fasted and refed 1) 60% cottonseed hulls-40% alfalfa dehy (high roughage), 2) LCP, 3) 15% protein (HCP), 4) LCP + BV or 5) LCP + LAC. Rumen fermentative capacity declined 74% (P less than .05) during feed and water deprivation, but returned to control levels by d 7 of realimentation. On d 3 of realimentation, steers fed the LCP and MCP diets had molar proportions of ruminal butyrate in excess of 35%. Steers fed the hay, LAC and BV diets did not have a high butyrate fermentation. In trial 2, calves lost about 15% of their body weight during feed and water deprivation. Calves fed the high roughage diet appeared to return to prefast feed and energy intakes more slowly than steers fed the medium roughage diets. Results of this study indicate that rumen fermentative capacity is a factor limiting feed intake in fasted calves for 7 to 14 after the reintroduction of feed and water.

Influence of prefast feed intake on recovery from feed and water deprivation by beef steers.

A trial was conducted with 60 steers (257 kg) to determine the influence of prefast feed intake on recovery from feed and water deprivation. For 3 d, steers were fed a 35% roughage diet at 1 (LI) or 1.75% (MI) of body weight or ad libitum (AL). Steers were then deprived of feed and water for 24 h, limit-fed and watered for 24 h, deprived of feed and water for 48 h and then allowed ad libitum feed and water consumption for 2 wk. A fourth group of control steers was fed at 1.75% of body weight during the alimentation period and was not fasted. Realimentation feed intake was positively related to prefast feed intake, with the order of realimentation feed intake being AL greater than MI greater than LI (P less than .05). During deprivation, rumen volume declined (P less than .05) in AL-fed steers, but was not affected in LI and MI steers. Blood hemoglobin and serum urea-N increased during deprivation in all fasted groups. Prefast serum cholesterol levels were inversely related to prefast energy intake. During deprivation, rumen fluid total volatile fatty acid (VFA) concentrations and propionate and butyrate molar proportions declined (P less than .05) and acetate, isobutyrate and valerate + isovalerate molar proportions increased (P less than .05). Results of this study indicate that an increased prefast feed intake will provide a greater reserve of energy, water and electrolytes to the steer during deprivation and result in a shorter postfast adaptation period.

Feed intake, rectal temperature, and serum mineral concentrations of feedlot cattle fed zinc oxide or zinc methionine and challenged with infectious bovine rhinotracheitis virus.

Three experiments were conducted using feedlot steers in a randomized block design to determine the effect of zinc methionine (ZnMet) and zinc oxide (Exp. 3) on feed intake (DMI), rectal temperature, and serum mineral concentrations of feedlot cattle challenged with infectious bovine rhinotracheitis virus (IBRV). All the steers used were seronegative to IBRV. Steers were adapted for 7 d to their respective diets and challenged with 3.7 x 10(5) plaque forming units of IRBV on d 0 of each experiment. Live BW, rectal temperature, and individual daily DMI were recorded for 14 d. Blood samples were taken on d 0, 7, and 14. In Exp. 1, daily DMI of the control steers (Zn = 31 ppm) decreased 50% compared with 15% in the ZnMet (Zn = 90 ppm) steers 3 d after IBRV challenge. By d 6, the ZnMet steers had regained their pretrial mean daily DMI, but the control steers took 11 d. The ZnMet steers had lower (P less than .05) mean rectal temperature than the control steers on d 7 and 12. In Exp. 2, the control (Zn = 35 ppm) steers had lower (P less than .05) daily DMI on d 8 to 12 than the ZnMet (Zn = 89 ppm) steers. In Exp. 3, the mean decrease in daily DMI tended to be more rapid in the ZnO steers than in the control and ZnMet steers. All steers had the lowest daily DMI on d 5 and 6, coinciding with the highest rectal temperature. Serum Zn, P, and Mg concentrations decreased and serum Cu increased in all steers after infection. These data suggest that dietary Zn enhanced the recovery rate of IBRV-stressed cattle.

Nitrogen kinetics of infectious bovine rhinotracheitis-stressed calves.

Eight crossbred feeder steers were used in two consecutive N balance studies to investigate the effects of infectious bovine rhinotracheitis virus (IBRV) on N kinetics. Balance Study 1, which followed a 10-d acclimation phase, consisted of 7 d of sample collection referred to as the healthy phase (d -7 to d -1). Study 2, the IBRV-infected phase, began 2 d after a nasal IBRV challenge and continued for 6 d (d 2 to d 8). A stable isotope, [15N]-glycine, was used to determine N kinetics in both studies. Steers weighed 203 kg at the beginning of the study, 208 kg at IBRV infection and 194 kg at the end of study. Infection with IBRV increased (P less than .05) urinary N excretion from 17.9 to 31.5 g/d. Daily N balance was reduced (P less than .05) during infection from 21.2 to -3.3 g/d. Total serum proteins increased (P less than .05) during infection from 6.6 to 7.1 g/100 ml, the increase being predominantly in the alpha and gamma globulin fractions. Blood urea-N increased (P less than .05) during infection from 6.5 to 12.9 mg/100 ml. The urine excretion curve of the stable isotope and the N balance data indicated that IBRV infection increased N turnover and altered tissue utilization of N.

The effect of pre-fast diet and transport on nitrogen metabolism of calves.

Two trials were conducted to determine the effects of transport stress and pre-transport diet on N losses, blood chemistry and ruminal variables of steers. In each trial, 16 crossbred steers (261 kg avg weight) were assigned to four groups in a 2 X 2 factorial arrangement of treatments. Treatments consisted of either transported or non-transported groups and two pre-transport dietary regimens (alfalfa hay or a 50% concentrate diet fed for 3 d before fasting). The alfalfa hay contained 14.6% crude protein (CP) and had a calculated metabolizable energy (ME) content of 1.92 mcal/kg. The 50% concentrate diet contained 15.5% CP and had a calculated ME content of 2.23 mcal/kg. Steers in the transport group were transported for 13 h in trial 1 and 46 h in trial 2, while the remaining steers were not transported. Both groups were withheld from feed and water during the observation periods. Urine and feces were collected and blood samples were obtained at intervals during the observation periods. Transport increased (P less than .05) urinary and total N excretion and nonevaporative water losses compared with fasting alone. Calves fed the 50% concentrate diet had lower N and nonevaporative water losses than calves fed hay, probably due to lower pre-fast N and water intakes. Ruminal total volatile fatty acid (VFA) concentrations and molar proportions of propionate and butyrate declined (P less than .05) with time in all groups, while molar proportions of acetate and minor VFA increased. Results of these trials indicate transportation stress can cause a significant increase in total N excretion and nonevaporative water loss compared with feed and water deprivation alone. Losses of N and water were lower in calves fed a 50% concentrate diet rather than hay for 3 d before the fasting period, probably because of lower pre-fast N and water intakes.

Influence of yeast culture on feeder calves and lambs.

Four experiments were conducted to determine the influence of yeast culture on 1) the health and performance of feeder calves, 2) the response of calves to an infectious bovine rhinotracheitis virus (IBRV) infection, and 3) nutrient utilization in lambs fasted for 3 d. In Exp. 1, 108 feeder calves were transported from Tennessee to Texas (1,600 km) and fed receiving diets containing 0 or .75% yeast culture and .35 or .69% P in a 2 x 2 factorial arrangement of treatments. In Exp. 2, 101 calves were transported 950 kg from Austin, TX to Bushland, TX and fed receiving diets containing 0, .75, 1.125, or 1.5% yeast culture. Yeast culture did not significantly affect the health or performance of calves in either experiment, although morbid calves fed yeast culture required fewer (P less than .05) days of antibiotic therapy in Exp. 2. In Exp. 3, feeder steers were fed diets containing 0 or .75% yeast culture and challenged intranasally with IBRV. Calves fed yeast culture tended to maintain heavier weights and higher DMI during IBRV infection than did steers fed the control diet. In Exp. 4, feeder lambs were fasted for 3 d and refed diets containing 0, .75, 1.125, or 1.5% yeast culture during a N and mineral balance trial. Lambs fed yeast culture had greater (P less than .08) N balance and tended to have greater Zn and Fe balance than control lambs. Results of these studies are interpreted to suggest that supplementation of morbid calves with yeast culture can have beneficial effects (fewer sick days, higher feed intakes) and that these effects may be mediated by improved N, Zn, and Fe metabolism.

Effects of pretransit diets and post-transit potassium levels for feeder calves.

Two trails were conducted to study effects of K addition to receiving diets and the effects of feeding either a 55% concentrate diet or hay before shipment on the health, performance and blood chemistry of transported calves. One-hundred seven steer calves were used in trial 1 and 160 steer calves in trial 2. Postshipment diets for trial 1 contained .9 or 1.4% K and for trial 2 were .7, 1.3, 2.2 or 3.1% K. The preshipment diets were fed 3 d before shipment and the receiving diets were fed for 2 wk after feedlot arrival. Performance data were collected for 28 and 49 d for trials 1 and 2, respectively. Feeding a 55% concentrate diet before shipment significantly reduced mortality of transported calves. Potassium additions to the diet after arrival improved performance of transported calves. Upon arrival at the feedlot, calves fed the 55% concentrate diet preshipment had lower (P less than .05) plasma urea-nitrogen (PUN) values than calves fed hay preshipment. Blood packed cell volume (PCV) increased (P less than .05) as the receiving diet K level increased from .7 to 2.2%. The K recommended for transported calves was calculated to be 24.7 g/100 kg of body weight for the first 2 wk after arrival, 20% more than the requirement for nontransported calves.