Evaluation of isotonic sodium bicarbonate solution for alkalizing effects in conscious calves

After intravenous (i.v.) infusion of various volumes of 1.35%-isotonic sodium bicarbonate solution (ISB), acid-base equilibrium, blood pressure, plasma volume and biochemical parameters in healthy Holstein calves were studied. Four calves each were randomly assigned to the low-dose (LD; i.v. infusion of 5 ml/kg ISB), middle-dose (MD; i.v. infusion of 10 ml/kg ISB) and the high-dose groups (HD; i.v. infusion of 15 ml/kg ISB). Administration volumes of ISB in the LD, MD and HD groups were decided based on the first half volumes of 5, 10 and 15 mEq of base requirement by the acceptable equation. Systemic, pulmonary artery and central venous pressures, cardiac output and plasma osmotic pressure were not changed by ISB infusion and remained constant throughout the experiment for all groups. There was good correlation (r(2) = 0.950) between relative changes in base excess and infused volume of bicarbonate (y=2.491x). The coefficient of distribution for bicarbonate ions was calculated to be 0.401 (=1/2.491). Therefore, it is suggested that a value of 0.4 would be most appropriate when calculating the base requirements in calves. Therefore, the first half volumes of ISB correcting base deficits of 5, 10 and 15 mEq in calves were estimated to be 6, 12 and 18 ml/kg, respectively. On the basis of the findings in this study, ISB may be used to correct metabolic acidosis without altering the plasma osmotic pressure, hemodynamic status and respiratory function in the calves.     

Comparison of the effects of isotonic and hypertonic sodium bicarbonate solutions on acidemic calves experimentally induced by ammonium chloride administration

The objectives of this study were to evaluate and compare the effects of intravenously (IV) administered infusion of isotonic solution (ISB) or hypertonic sodium bicarbonate solution (HSB) on acid-base equilibrium and the plasma osmolarity in acidemic calves experimentally induced by 5 M-NH(4)Cl, IV infusion (1.0 ml/kg, over 1 hr). The ISB and HSB infusion induced progressive and significant increases in their HCO(3)(-) and BE levels that persisted throughout the period of fluid administration. The plasma osmolarity in the ISB groups was significantly decreased. The plasma osmolarity in the HSB group was significantly higher than in the calves in the other groups (p<0.05). ISB solution might be safe and effective for treating and reviving conscious calves from experimentally induced metabolic acidosis.     

Clinical evaluation of sodium bicarbonate, sodium L-lactate, and sodium acetate for the treatment of acidosis in diarrheic calves

Thirty-six dehydrated diarrheic neonatal calves were used to study the effects of various alkalinizing compounds on acid-base status, the changes in central venous pressure (CVP) in response to rapid IV infusion of large volumes of fluid, and the correlation of acid-base (base deficit) status, using a depression scoring system with physical determinants related to cardiovascular and neurologic function. Calves were allotted randomly to 4 groups (9 calves/group). Over a 4-hour period, each calf was given two 3.6-L volumes (the first 3.6 L given in the first hour) of a polyionic fluid alone (control group) or were given the polyionic fluid with sodium bicarbonate, sodium L-lactate, or sodium acetate added (50 mmol/L). Acid-base status, hematologic examination, and biochemical evaluations were made immediately before infusion of each fluid (at entry) and after 3.6, 4.8, and 7.2 L of fluid had been given. Compared with control values, bicarbonate, lactate, and acetate had significantly greater alkalinizing effects on pH (P less than 0.01) and base deficit (P less than 0.01) after 3.6, 4.8, and 7.2 L of fluid were given. Bicarbonate had the most rapid alkalinizing effect and induced greater changes in base deficit (P less than 0.01) than did acetate or lactate at each of the 3 administered fluid volumes evaluated. Acetate and lactate had similar alkalinizing effects on blood. Rehydration alone did not improve acid-base status. The CVP was elevated in 10 (28%) of the 36 calves after 1 hour of fluid (3.6 L) administration, but significant differences in body weight, PCV, and clinical condition or depression score at entry were not found between calves with elevated CVP and those with normal CVP.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of unrestricted milk feeding on the growth and health of Jersey calves

This study was conducted to determine the effect of feeding high milk volumes on the growth rate, health and cross-sucking behaviour in group-fed Jersey calves. Three-day-old heifers (n = 120) in a seasonal calving dairy herd were randomly assigned to one of 6 treatment groups. Three groups received high milk volumes (HMV), consisting of ad libitum milk or milk replacer feeding twice a day, while 3 groups received restricted milk volumes (RMV), consisting of 2 l twice daily, during the pre-weaning period. After a pre-weaning period during which feeding was reduced to once daily, all calves were weaned at 42 days and monitored until 60 days of age. Adjusting for birth mass, birth date, dam parity and sire, average daily mass gain (ADG), both pre-weaning (days 0-42) and overall (days 0-60), was higher in HMV than in RMV calves (P < 0.001). After weaning, growth rates showed no differences and at 60 days of age the HMV calves maintained a 6.74 kg advantage in mean body mass (P < 0.001). The mean intake of dry starter feed was higher in RMV than in HMV calves. Overall feed conversion rate of HMV calves was 9.6 % better than RMV calves. However, the variable cost per kg mass gain was 12 % higher for HMV calves. In the RMV groups 75 % of calves showed cross-sucking behaviour pre-weaning and 18 % post-weaning, whereas in HMV calves the proportions were 2 % and 7 %, respectively. There was no significant effect of milk volume on the incidence of diarrhoea. We conclude that the feeding of high volumes of milk to Jersey calves has a positive effect on growth rate, without compromising health or reducing solid feed intake after weaning. However, the higher cost of such a feeding system may limit its implementation.     

Norfloxacin nicotinate pharmacokinetics in unwearied and weaned calves

The pharmacokinetics of norfloxacin nicotinate were investigated in unweaned and weaned calves. Following intravenous administration of 7.5 and 15 mg/kg (calculated as norfloxacin base) the clearance values were 8.5/pm 2.0 or 7.7/pm 1.2mL/min·kg (unweaned calves) and 11.7/pm 3.2 or 16.1/pm 3.3mL/min·kg (weaned calves). Norfloxacin mean residence time and volume of distribution values were 211/pm 33 or 227/pm 41 min (unweaned calves) and 185/pm 79 or 128/pm18 minutes (weaned calves), and 1.8/pm0.3 or 1.7/pm0.1L/kg (unweaned calves) and 2.0/pm0.7 or 2.1/pm0.7L/kg (weaned calves) following administration of the lower and higher dose, respectively. These results indicated that norfloxacin pharmacokinetics were similar at a dose range of 7.5-15 mg/kg. However, a significant difference was observed in clearance, mean residence time and the half-life values between the unweaned and weaned calves. The only major pharmacokinetic parameter which did not show a significant difference between the investigated groups was the volume of distribution. The pharmacokinetic differences between the non-ruminating (unweaned) and ruminating (weaned) animals seemed to result from changes in drug clearance. The absorption rate after intramuscular administration appeared to change as a result of dose increase. Norfloxacin bioavailability following intramuscular administration ranged from 73 to 106%. The results suggested that larger injection volumes may reduce the extent of absorption.     

Use of febantel or ivermectin for treatment of calves with experimentally induced Bunostomum phlebotomum infection

In the first of 2 separate trials, the efficacy of febantel, given at a dosage of 5 mg/kg of body weight, was assessed in calves with 60-day experimentally induced Bunostomum phlebotomum infection. Ten calves were given febantel paste, and 10 were given the vehicle only. All 20 calves were necropsied 7 days after cessation of treatment. Compared with untreated calves, febantel-treated calves harbored 99.4% fewer nematodes. In the second trial, the efficacy of ivermectin, given as a paste formulation at a dosage of 0.2 mg/kg, was assessed in calves with experimentally induced B phlebotomum infection. Ivermectin was given at 18 (n = 6) and 60 (n = 6) days after infection. At each treatment date, 3 additional calves were given vehicle only. At 67 days after infection, all calves were euthanatized. Efficacies of ivermectin against 18- and 60-day infections were 100 and 99.8%, respectively. Both anthelmintic preparations were easily administered, and adverse reactions were not observed.     

Investigations on the association of D-lactate blood concentrations with the outcome of therapy of acidosis, and with posture and demeanour in young calves with diarrhoea

The objective of this prospective study was to elucidate whether amounts of bicarbonate needed for correction of acidosis and normalization of clinical signs are influenced by blood D-lactate concentrations in calves with diarrhoea. In 73 calves up to 3 weeks old with acute diarrhoea and base excess values below -10 mmol/l correction of acidosis was carried out within 3.5-h by intravenous administration of an amount of sodium bicarbonate which was calculated using the formula: HCO (mmol) = body mass (kg) x base deficit (mmol/l) x 0.6 (l/kg). Clinical signs, venous base excess, and plasma D-lactate concentrations were monitored immediately following admission, following correction of acidosis at 4 h and 24 h after admission. The base excess and plasma D-lactate concentrations throughout the study were -17.8 +/- 4.0, -0.4 +/- 0.4, -3.0 +/- 5.5 mmol/l (base excess), and 10.0 +/- 4.9, 9.8 +/- 4.8, 5.4 +/- 3.4 mmol/l (D-lactate) for the three times of examination. Metabolic acidosis was not corrected in more than half of the calves (n = 43) by the calculated amount of bicarbonate, whereas the risk of failure to correct acidosis increases with D-lactate concentrations. The study shows that calves with elevated D-lactate concentrations do not need additional specific therapy, as D-lactate concentrations regularly fall following correction of acidosis and restitution of body fluid volume, for reasons that remain unclear. However, calves with distinct changes in posture and demeanour need higher doses of bicarbonate than calculated with the factor of 0.6 in the formula mentioned above probably because of D-hyperlactataemia.     

Metabolic profile of newborn calves and levels of immunoglobulins in the first days of life

After examination of the clinical state of 128 new-born calves, blood was collected from their vena jugularis for the determination of blood actual pH value, concentration of lactic acid, pCO2, base excess, buffer base and standard acid bicarbonate. The course and difficulty of parturition exerted a significant influence on the vitality of the calves and on the studied parameters of acid-base state. In the normally born calves, compared with those after dystocia, the following values were obtained: pH 7.20 +/- 0.03 : 7.11 +/- 0.07, pCO2 = 8.4 +/- 0.9 : 10.0 +/- 1.1 kPa, base excess -2.30 +/- 2.10 : 5.80 +/- 4.60 mmol/l, buffer base 43.0 +/- 2.4 : 39.5 +/- 6.5 mmol/l, standard acid bicarbonate 22.3 +/- 1.8 : 19.6 +/- 4.1 mmol/l and lactic acid concentration 5.6 +/- 2.0 : 10.7 +/- 5.1 mmol/l. The differences were statistically significant (P less than 0.05) and statistically highly significant (P less than 0.01). The continual study of the blood actual pH value and lactic acid concentration in the calves in the first 24 hours of life showed that with the same trend of changes in calves after dystocia the initial values were less favourable and that their normalization lasted longer. Attention is drawn to the importance of dystocia for the rise of respiratory metabolic acidosis and its effect on the vitality of newborn calves, and/or on their survival. The discussion deals with the importance of immunoglobulin levels in calves in the first days after birth for their further development. The determination of antibody content in colostral serum from the first milking in 33 and 29 cows on two farms showed great drawbacks in quality. A satisfactory level of IgG was found only in 36.36% and 58.62% of the cows, and a satisfactory level of IgM only in 12.12% and 24.13% of the studied cows. The determination of immunoglobulin content in their calves two to three days from birth (33 + 33 animals) showed normoglobulinemia only in 24.24% and 15.15% of cases. In 33 and 29 cows on two farms the colostrum serum from the first milking had an average content of immunoglobulins of class G amounting to 27.99 +/- 20.25 mg/ml and 36.95 +/- 21.62 mg/ml, and class M amounting to 3.64 +/- 1.25 and 2.04 +/- 1.42 mg/ml. Three days from birth, their calves had an IgG content of 4.25 +/- 2.57 mg/ml and 3.99 +/- 1.86 mg/ml and an IgM content of 0.30 +/- 0.20 and 6.38 +/- 0.25 mg/ml.     

Diagnosis of copper deficiency and effects of supplementation in beef cows.

The effects of feeding supplementary dietary copper to a herd of 400 beef cows, were studied over a two year period. In the first year of the trial, the calves showed clinical signs of copper deficiency. There was improved growth following subcutaneous injection of copper ethylenediamine tetraacetate, and the treated calves had a 2.8% increase in adjusted weaning weights. In the second year of the trial pregnant cows were fed a basal ration of bromegrass silage, barley and minerals over the winter feeding period. The feed was supplemented with copper so that half received 5.5 mg/kg of copper on a dry matter basis and half 40 mg/kg. Calving occurred in the spring and half the calves were treated with injectable copper at birth and again at 12 weeks of age. There was no evidence of copper deficiency in the calves and there was no effect of high level copper supplementation on calf birth weight, or neutrophil candidacidal activity. Susceptibility to diarrhea varied in a complex fashion; morbidity was lowest in calves born to dams fed supplementary copper and highest in calves born to supplemented dams and injected with copper at birth. The cows and calves grazed the same copper deficient pasture over the summer. The average daily gain for calves born to supplemented cows was 0.999 +/- 0.010 kg/day (x +/- SEM) which was significantly greater than the 0.972 +/- 0.009 kg/day for calves from nonsupplemented dams (p = 0.044). The benefit of copper supplementation on 200 day weaning weight was estimated at 4.8 kg. Evidence of copper deficiency was seen when a herd test showed mean serum levels below 9 mumol/L and liver values below 0.09 mmol/kg wet matter.     

Urinary GGT/creatinine ratio and fractional excretion of electrolytes in diarrhoeic calves

The aim of this study was to monitor renal function in diarrhoeic calves and to determine the effectiveness of an applied fluid therapy. A total of 28 diarrhoeic (n = 18) and healthy (n = 10) Holstein-Friesian calves of different sexes, between 1 and 30 days of age, were used. Blood and urine samples were obtained from diarrhoeic calves before the treatment and then three more times at 24-h intervals during the treatment. From healthy calves, samples were taken only once. Therapy was started by the intravenous administration of 8.4% sodium bicarbonate and 0.9% sodium chloride solutions for the first 24 h, followed by the oral application of a commercial electrolyte solution (sodium chloride 3.5 g, trisodium citrate 2.9 g, potassium chloride 1.5 g and glucose anhydrous 20 g in 1 litre H2O) up to the 48th h of therapy. Before the therapy, the average levels of pH (7.10 +/- 0.12), bicarbonate (HCO3-) (16.48 +/- 3.80 mmol/l), base deficit (-12.65 +/- 5.97 mmo/l) and fractional excretion (FE) of sodium (0.16 +/- 0.11%) and potassium (15.07 +/- 8.56%) were significantly lower while serum urea (17.48 +/- 10.32 mmol/l) and creatinine (Cr) concentrations (169.72 +/- 98.12 micromol/l), haematocrit levels (45.13 +/- 13.60%) and urinary gamma glutamyl transferase (GGT)/Cr ratio (8.6 +/- 4.3 x 1/10(3) U/micromol) were significantly higher in diarrhoeic calves than in healthy calves. Alterations in parameters indicating the presence of renal dysfunction were normalised in the diarrhoeic calves that survived (83.3%). Three calves with severe metabolic acidosis and azotaemia died at the beginning of therapy. It was concluded that the FE of Na and K (FENa, FEK) and urine GGT/Cr ratio may have an important role in assessing renal function in diarrhoeic calves and in evaluating the effectiveness of an applied fluid therapy.     

Efficacy of danofloxacin 18% injectable solution in the treatment of Escherichia coli diarrhoea in young calves in Europe

The efficacy of danofloxacin 18% against naturally occurring Escherichia coli diarrhoea was investigated in calves at seven European sites. Treatment commenced on day 0, with either a single subcutaneous injection of danofloxacin 18% (n=267) at 6 mg/kg repeated on day 2 if required, or reference product containing baquiloprim/sulphadimidine (n=37) or gentamicin (n=98) administered as recommended. E. coli was isolated from 90% to 100% of calves pre-treatment, and the prevalence of serotypes K99 and F41 was 8-46% and 46-92%, respectively. In both treatments, the majority of calves (93.2-93.9%) showed clinical improvement and completed the studies. There were significant reductions for both treatments, in severity of clinical signs on days 4 and 10 compared to day 0 (P<0.0001), and between days 4 and 10 (P<0.05), but no significant differences between treatments (P>0.05). Danofloxacin 18% was clinically safe, and as effective as the reference products in the treatment of E. coli diarrhoea in calves.     

Production practices, calf health and mortality on six white veal farms in Ontario.

A group of 4863 white veal calves reared on six commercial white veal farms in Ontario were followed through production to describe calf characteristics and production levels. Patterns of morbidity, mortality, and culling were investigated at the farm, room and individual level. The majority of the calves were male Holsteins, with approximately half originating from Ontario. The mean average daily gain for shipped calves over the entire production period was 1.1 kg/day (SE = 0.002). The overall percentage of calves receiving at least one individual treatment was 59%, with an average number of treatment days per calf of 3.3. The majority of calves receiving one or more treatment days were first treated between the fourth and seventh week of production. The mortality rate was 3.7%, and 5.1% of the calves were culled. Pneumonia was the largest single cause of death. Peak death and cull losses occurred during the seventh and eighth week of production.     

Performance and Economic Returns of Stocker Cattle on Tallgrass Prairie Under Different Grazing Management Strategies

A 4-yr study was conducted to determine performance of stocker calves on tallgrass prairie under three grazing management strategies. Pastures were assigned to one of three grazing treatments. Grazing was initiated in June, and pastures were grazed only during the summer months for 57 to 104 d (79.5 ± 20.7 d). Two of the pastures were grazed season-long. Calves in one of the season-long treatments were fed a protein supplement during the second half of the grazing season; calves in the other season-long treatment were not supplemented (control group). The third pasture, an intensive early stocking (IES) treatment, was grazed at twice the stocking rate used in the season-long pastures for the first half of the grazing season (40 ± 11 d) and rested for the second half (39.5 ± 10 d). Individual stocker performance during the first half of the summer was similar among grazing treatments. Providing supplemental protein during the second half of the grazing season increased BW gain by 30 kg/ha during the last 40 d of the 80-d grazing season and increased BW gain by 12 kg/ha for the entire summer. Over the summer, IES stocker calves produced 24% more gain/ha than season-long stocked calves. Nonetheless, IES management was not more profitable than season-long grazing with or without protein supplementation. Under short-term ownership of calves in the IES system, fixed costs represented a large portion of the total cost.     

Clinical efficacy of intravenous hypertonic saline solution or hypertonic bicarbonate solution in the treatment of inappetent calves with neonatal diarrhea

BACKGROUND: The clinical efficacy of IV administered hypertonic saline solution and hypertonic bicarbonate solution (HBS) in the treatment of inappetent diarrheic calves has not been compared yet. HYPOTHESIS: HBS is more advantageous than hypertonic saline in the treatment of calves with severe metabolic acidosis. ANIMALS: Twenty-eight dehydrated, inappetent calves with neonatal diarrhea. METHODS: In 2 consecutive clinical studies, calves were initially treated with saline (5.85%; 5 mL/kg body weight [BW] over 4 minutes; study I: N = 16) or bicarbonate solution (8.4%; 10 mL/kg BW over 8 minutes; study II: N = 12), respectively, followed by oral administration of 3 L isotonic electrolyte solution 5 minutes after injection. Clinical and laboratory variables were monitored for 72 hours. RESULTS: Treatment failed in 6 calves of study I and in 1 calf of study II as indicated by a deterioration of the general condition. All treatment failures had more severe metabolic acidosis compared with successfully treated calves before treatment. In the latter, rehydration was completed within 18 hours after injection; metabolic acidosis was corrected within 24 hours (study I) and 6 hours (study II) after injection. CONCLUSIONS AND CLINICAL IMPORTANCE: Diarrheic calves with slight metabolic acidosis (base excess [BE] >-10 mM) can be treated successfully with hypertonic saline. HBS is appropriate in calves without respiratory problems with more severe metabolic acidosis (BE up to -20 mM). Intensive care of the calves is required to ensure a sufficient oral fluid intake after the initial IV treatment.     

Use of trainer animals to improve performance and health of newly arrived feedlot calves

Four trials were conducted to determine the efficacy of using trainer animals to improve the health and performance of newly arrived feedlot calves. For all trials, trainer animals were given 3 wk to adapt to the feedlot before arrival of the feeder calves and initiation of the trials. Trainer animals were present with newly received feedlot calves for 14 d after arrival and then were removed from the pens for the remaining 14 d of the experiments. In Trial 1, trainer animals were six crossbred beef steers and six mature cull beef cows. Newly received calves were allotted to 18 pens with 10 calves/pen. Six pens contained a trainer steer and six pens contained a trainer cow. Similar procedures were used for the subsequent three trials, except 12 trainer cows and 24 pens were used, and in Trial 4 half of the calves were allotted to pasture paddocks for 14 d before placement in their feedlot pens. During wk 1 of Trial 1, calves with trainer cows and steers gained weight more rapidly (P < .10) than those without a trainer animal (1.12 vs .67 kg/d, respectively). During wk 2, this trend was reversed and overall gains did not differ (P > .20) among treatment groups. Morbidity was 16.7 for control calves, 28.3% for calves with trainer steers, and 8.3% for calves with trainer cows. Four of six trainer steers required antibiotic treatment for respiratory disease. On d 1, a greater (P < .05) percentage of calves in the trainer cow group (81.7%) were observed eating during the first 30 min after feeding compared with either the steer trainer group (60%) or the control group containing no trainer animal (48.3%). This trend continued on d 2 but was not evident on d 3 or 7. In Trial 2, overall gains were 10% greater (P < .06) and final BW was higher (P < .01) for calves with trainer cows than for those without trainers. Trainer cows resulted in a substantial reduction (P < .01) in calf morbidity compared with calves housed alone. In Trial 3, trainer cows did not improve performance or health of newly received calves. More (P < .07) calves with trainers than without were eating 5 min after feeding on d 1, 2, 4, and 8. In Trial 4, the presence of trainer cows the first 2 wk did not affect (P > .27) gains. However, calves placed on pasture after arrival had lower (P < .03) gains during wk 1 than those housed in the feedlot. Calves placed in pasture paddocks upon arrival had more than twice (P < .01) the incidence of morbidity of those placed directly in the feedlot. In these trials, trainer cows had a significant effect on eating behavior of newly received calves, but health and performance benefits were variable.     

An examination of the prevalence of and risk factors for shedding of Cryptosporidium spp. and Giardia spp. in cows and calves from western Canadian cow-calf herds

The primary objectives of this study were to describe the prevalence and risk factors for Cryptosporidium spp. and Giardia spp. infection in cows and calves during the calving season in western Canadian cow-calf herds. Through the calving season of 2002, fresh fecal samples were collected from 560 beef cows and 605 calves in western Canada. Feces were examined for the presence of Cryptosporidium spp. and Giardia spp. using a quantitative sucrose gradient immunoflourescent antibody test. Samples were collected from mature cows on 59 farms and from calves on 100 farms. Only 1.1% (5/560) of the cows were positive for Cryptosporidium spp. whereas 3.1% (19/605) of the calves were positive. Prevalence for Giardia spp. was much higher; Giardia spp. was detected in 17.0% (95/560) of the cow and 22.6% (137/605) of calf fecal samples. Data describing herd management practices, treatment and disease history, age, gender, breed and fecal consistency were gathered to assess potential risk factors associated with shedding. The association between the risk of shedding and average precipitation from December to June and ecological region were also evaluated. Risk factors for infection with Cryptosporidium spp. in either cows or calves could not be evaluated because the multilevel model would not converge due to the relatively low prevalence of the organism in this sample. The prevalence for Giardia spp. was sufficient to explore potential risk factors in both cows and calves. No risk factors were identified for Giardia spp. in beef cows following calving. After the construction of a multivariable model, the only significant predictors for Giardia spp. presence in beef calves was dam age and calf age. Calves born to 2-year-old heifers were 2.3 (95% CI, 1.09-5.06; P = 0.031) times more likely to be shedding Giardia spp. then calves born to cows that were 4-10 years of age. Calves that were 9-18 days of age and calves that were > 18 days of age were 22.4 (95% CI, 5.88-88.18; P < 0.001) and 150 (95% CI, 39.72-603.19; P < 0.001) times more likely, respectively, to be shedding Giardia spp. than calves < or = 4 days of age.     

Prevalence of Cryptosporidium parvum infection and pattern of oocyst shedding in calves in Japan

Cryptosporidium parvum infection and the pattern of oocyst shedding were observed in calves. A total of 480 fecal samples were collected from 30 calves (age, < or =30 days) over a period of 10 months from June 1998 to March 1999. A sucrose centrifugal flotation technique revealed 28/30 (93%) calves were passing Cryptosporidium oocysts. Oocyst shedding was first detected on the sixth day after birth, with 8% of the calves testing positive. This rate increased day by day and reached approximately 80% by day 15. Oocyst shedding varied from 1 to 13 days, with a mean of 7 days. Calves infected with C. parvum had a significantly higher rate of diarrhea (33%) than non-infected calves (8%) (P<0.05), suggesting C. parvum infection as the likely cause. The mean number of oocysts excreted by calves < or =30 days old was approximately 6x10(7) per gram of feces. These results indicated that one calf would excrete some 6x10(11) oocysts in the first month after birth, taking both the quantity of feces in a day and the period of excretion into consideration. Accordingly, it is clear that calves are important in the spread of cryptosporidiosis to calves and humans.     

The effects of feeding milk to diarrheic calves supplemented with oral electrolytes.

The effects of feeding different levels of milk to diarrheic calves (n = 19) supplemented with oral electrolytes were investigated. In the early stages of the disease the calves were fed either enough milk to maintain normal growth in a healthy calf, one half that volume or no milk. The three groups were further subdivided according to whether or not the electrolyte solution contained bicarbonate. A full milk ration allowed uninterrupted weight gains of 1% body weight/day (p = 0.003), but caused greater inappetence (p = 0.003 to 0.037) at the beginning of the trial than lower levels of milk intake. Electrolyte solutions with bicarbonate reduced growth rates in milk fed calves (p = 0.014). The density of fat stores increased with the level of milk feeding (p = 0.04 to 0.053). The mitotic index of the duodenal mucosa increased with milk feeding (p = 0.08), indicating a superior mucosal regeneration potential. Thymic atrophy was pronounced in those calves fed no milk (p = 0.001). It was concluded that the continued feeding of milk to diarrheic calves was beneficial. Electrolyte solutions containing bicarbonate should be avoided when milk is fed to diarrheic calves.     

Restricted suckling of tropical dairy cows by their own calf or other cows' calves

The objective of this study was to compare restricted suckling of tropical cows by their own or another cow's calf with artificial rearing of the calves and no suckling. In Exp. 1, cows were mechanically milked twice daily, after which for 15 min they were either suckled by their own calf (Treatment O) or multiple-suckled by other cows' calves (Treatment M) or unsuckled, with the calves reared artificially (Treatment A). Machine milk yield was similar for the three treatments, but in the two suckling treatments the additional milk consumed by the calf increased (P = 0.02) total production (2,682, 2,634, and 2,336 kg/lactation for Treatments O, M, and A, respectively). Machine milk fat concentration was reduced (P = 0.05) by suckling (2.90, 3.07, and 3.20% for Treatments 0, M, and A, respectively), but the milk sampled just before suckling (to represent that taken by the calves) had a high fat concentration (mean 7.9%). Machine milk somatic cell count was also reduced (P = 0.05) by suckling, from 106,000/mL (Treatment A) to 85,000/mL (Treatment M) and 95,000 (Treatment O). Cows suckling their own calf lost more weight and body condition than cows whose calves were reared artificially, with multiple-suckled calves intermediate. Cows suckling their own calf had postpartum interval to first estrus increased (P = 0.01) by 31 d and conception rates to first service of 44% compared to 77% for the other two treatments (P = 0.01). The growth of the suckled calves was compared with that of the artificially reared calves, which were given recommended milk allowances. The artificially reared calves consumed more milk and concentrates, which were available ad libitum to all calves, and gained (P = 0.03) 0.07 kg/d more weight than suckled calves. A second experiment determined that suckling once daily did not reduce reproductive performance compared to artificial rearing. We conclude that suckling cows twice daily increases total milk production but reduces body weight in early lactation. Cows suckling their own calves have reduced reproductive performance compared to those suckling other calves or reared artificially.     

Effects of Metaphylactic Antibiotics on Behavior of Feedlot Calves

Three 21-d trials were conducted at a commercial feedlot near Wellton, Arizona to determine the effects of metaphylactic injectable antibiotics on feeding and watering behavior and on animal health and growth performance of feedlot calves. Newly received male calves (n = 150, 150, and 148 for Trials 1, 2, and 3, respectively) were randomly assigned to one of four treatments: 1) no injectable antibiotic (control), 2) tilmicosin (TIL) subcutaneously (s.c.) 3) florfenicol i.m. (FIM), or 4) florfenicol s.c. (FSC). Throughout the 21-d trials, calves were observed and documented as morbid or healthy. Daily feeding and watering behaviors were collected for trials 2 and 3. A smaller (P=0.001) percentage of TIL, FIM, and FSC calves were identified as morbid (average, 27%) compared with control calves (47%), and ADG was greater (P=0.04) for TIL, FIM, and FSC calves (average, 0.42 kg/d) than for control calves (0.23 kg/d). Calves castrated before arrival had greater (P=0.001) ADG (0.53 vs 0.21 kg/d) and lower (P=0.05) mortality (0 vs 3.5%) during the first 21 d than did calves castrated upon arrival at the feedlot. Calves that remained healthy had greater (P=0.001) ADG than did calves that became morbid (0.78 vs−0.03 kg/d). Calves treated with TIL, FIM, or FSC had increased (P=0.02) feeding bouts per day in Trial 3 compared with control calves (average, 11 vs 9 bouts/d). Total feeding time was increased (P=0.005) for FIM calves compared with control, TIL, and FSC calves in Trial 3. No differences (P>0.10) were observed in watering behavior because of antibiotic treatment. Metaphylactic injectable antibiotics administered upon calves’ arrival at the feedlot did not reduce the total time newly received feedlot calves spent feeding, decreased the incidence of morbidity by 43%, and improved growth performance during the 21-d receiving period.