Effects of different iron contents in the milk replacer on the development of iron deficiency anaemia in veal calves.

The effect of different iron concentrations in the milk replacer on the development of iron deficiency anaemia during a fattening period of 28 weeks was studied in three groups of 14 calves. The iron contents in the milk replacer differed during the first seven weeks: 60, 100 and 150 mg Fe/kg in groups A, B and C, respectively. In all three groups blood haemoglobin, mean corpuscular volume, plasma iron concentration and saturation decreased during the fattening period, whereas the total iron-binding capacity increased. At week 7, liver iron concentrations were high with a large individual variation [A: 201 (61-706), B: 99 (47-129), C: 296 (77-1572) micrograms/g dry matter]. During the fattening period, liver iron concentrations decreased, with the lowest values at week 25 [A: 54 (34-82), B: 55 (44-83), C: 57 (42-79) micrograms/g dry matter]. Muscle iron concentrations decreased between week 7 and 19. Except plasma iron and saturation in group C, no differences in haematological and tissue iron variables were found throughout the fattening period in spite of different iron contents in the milk replacer during the first seven weeks.     

Mucosal uptake,mucosal transfer and retention of iron in veal calves

A method for studying iron absorption in humans was adapted to veal calves. Three 10-week-old calves with moderate (calves 1 and 2) or severe (calf 3) iron deficiency were given an abomasal injection of⁵⁹Fe and⁵¹Cr and all their faeces were collected over 15 days in order to measure mucosal uptake, mucosal transfer and retention of iron. The mucosal uptake was 62.2, 53.4 and 71.8% in calves 1, 2 and 3, respectively. The iron retention measured 14 days after administration of the test dose was 57.4, 52.3 and 56.4% in calves 1, 2 and 3, respectively. Maximal plasma activity was found in all three calves between 1 1/2 and 2 h after injection of the test dose. The plasma activity decreased rapidly, with a slight increase between the 5th and the 10th hour. After 21 h, less than 0.25% of the injected dose was still present in 1 litre of plasma. Not all the⁵¹Cr was recovered in the faeces. No⁵⁹Fe was found in the urine but some⁵¹Cr could be detected. The results of this study show that the method described is useful for measuring the different steps of iron absorption in iron-deficient veal calves.Abbreviations Hb haemoglobin concentration - MCV mean corpuscular volume - PCV packed cell volume - PI plasma iron - RBC red blood cell count - R iron retention - TIBC total iron-binding capacity - TIBC-SAT saturation of the total iron-binding capacity - U mucosal uptake     

Pharmacokinetics of florfenicol in veal calves

The pharmacokinetic disposition of florfenicol was described in veal calves after administration of a single 22-mg/kg dose intravenously, orally after a 12-h fast and orally 5 min post feeding. Both serum concentrations and urinary excretion were studied. After intravenous administration the median elimination half-life was 171.9 min while the half-life of the distribution phase was 5.9 min. The median body clearance (Cl) and apparent volume of distribution (Vz) were 2.85 ml/kg/min and 0.78 l/kg, respectively. Following oral administration the median bio-availability (f) was 0.88 for calves dosed after a 12-h fast and 0.65 for calves dosed 5 min post feeding. Calves given the oral doses had a complex absorption pattern with delayed absorption. Slightly more than 50% of the administered dose both orally and intravenously was recovered as unchanged florfenicol in the urine by 30 h.     

Distribution of iron and copper in the liver and spleen of veal calves in relation to the concentration of iron in the diet

The distribution of iron and copper in the liver and spleen of veal calves was determined in a group of calves fattened with a commercial milk replacer supplemented with 5 ppm iron and in a control group fed the unsupplemented milk replacer. No marked variations were detected in the distribution of iron and copper. A liver biopsy is therefore likely to be a representative sample of the whole liver with respect to iron and copper concentration.     

Transportation of veal calves in Switzerland

The analysis and optimization of transportation routes of calves to slaughterhouses by means of a GIS (geographical information system) route planning and time limitation software for the fleet management in transportation industry was performed. As basic data the farms (last locations of the calves) and the slaughterhouses were available in each case with addresses and coordinates. 150 data records from 258 veal calves could be evaluated. None of the calves was transported longer than 6 hours. Therefore, in all cases the Swiss law for animal protection was obeyed concerning maximum length of transportation time. In the road model, 82% of calves were transported too far.     

Some indicators of welfare of crated veal calves on three dietary iron regimens

Holstein calves were managed from less than 1 wk of age as in the special-fed veal industry but subjected to three dietary regimens (n = 10/group): low dietary iron (LI = approximately 5 mg iron/kg dry milk replacer) throughout 16 wk; 2) high then low dietary iron (H-LI = 140 mg/kg through d 18, then approximately 5 mg/kg through wk 16; a typical industrial scheme) or 3) high dietary iron (HI = approximately 105 mg/kg throughout the study). Several physiologic, behavioral and health indicators of welfare were monitored at various times. From wk 7 on, blood hemoglobin concentration was higher in HI calves than in LI, whereas that in H-LI calves was intermediate. Blood red cell count was higher in HI calves than in LI from wk 11 to 16, and was higher in HI than in H-LI from wk 14 to 16. Ratio of blood segmented neutrophils to lymphocytes (an indicator of stress) did not differ due to dietary regimen. Between wk 2 and 16, lying time increased from 69.5 to 76.6% of total time. Oral behaviors (e.g., licking and gnawing) occupied less than 15% of total time. Dietary regimen did not affect time spent either lying or engaging in oral behaviors. Calves in all dietary-regimen and slaughter-age groups experienced high frequencies of pneumonia, digestive-tract maladies and trichobezoars, but neither disease nor medical-treatment frequency was related to dietary regimen. Live, hot-dressed carcass and liver weights of the five calves/group slaughtered at 16 wk were not affected by dietary regimens, but carcass grade was highest for LI calves and lowest for HI.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ferrokinetic studies in normal and iron deficiency anemic calves.

Ferrokinetic studies were performed on control calves and on calves with experimentally induced iron deficiency anemia, all 15 weeks old.The plasma iron clearance half time was about 4 times shorter in the experimental than in the control group. The low plasma iron concentration in the anemic calves was partially compensated by a more rapid plasma iron disappearance. Therefore the difference in the plasma iron turnover rate was reduced.The mean value of plasma iron daily renewal rate was about 3 times higher in the experimental than in the control group.The maximum uptake of injected ⁵⁹Fe into blood cells was reached 14 to 16 days after injection. The uptake of ⁵⁹Fe was about 10% higher in the control than in the experimental group.Using the values from the ferrokinetic study, the iron need for calves could be estimated. The requirement of iron to maintain a normal and constant Hb in a calf weighing 100 kg at a growth rate of 1 kg/daily was estimated as being 17.5 mg/day. Based on information in the literature and assuming a retention of dietary Fe of 25%, the total daily iron need for such a calf gaining 1 kg/day would be 160–180 mg.     

Oral absorption and bioavailability of flumequine in veal calves

Summary

The oral absorption and bioavailability of flumequine was studied in 1‐, 5‐ and 18‐week‐old calves following intravenous and oral administration of different formulations of flumequine (Flumix^®, Flumix C^® and pure flumequine). Increasing age had a negative influence on the C_max after the administration of Flumix^®, based on a larger V_D in the older calves. The C_max decreased from 5.02 ± 1.46 μg/ml in the first week to 3.28 ± 0.42 μg/ml in the 18th week. Adding colistin sulfate to the flumequine formulation and administring pure flumequine mixed with milk replacer had a negative effect on the C_max of flumequine after oral administration of 5 and 10 mg/kg body weight. The bioavailability of the orally administered flumequine formulations was 100% in all cases except after the administration of Flumix C^®, for which it was 75.9 ± 18.2%. The urinary recovery of flumequine after intravenous injection of a 10% solution varied from 35.2 ± 2.3% for Group B. to 41.2 ± 6.3% for Group C.

The dosage of 5 mg/kg body weight Flumix^® twice daily in 1‐week‐old veal calves is sufficient to reach therapeutic plasma concentrations, based on a MIC value of 0.8 μg/ml of the target bacteria.

In older calves it is advisable to increase the dosage 7.5 or 10 mg/kg body weight every 12 hours. In combination with colistin sulfate it is also advisable to increase the dosage slightly because of the negative effect of the colistin sulfate on the C_max of flumequine.     

Pharmacokinetics of oxytetracycline and therapeutic implications in veal calves

Pharmacokinetic parameters of oxytetracycline were analysed in healthy preruminant veal calves after intravenous, intramuscular and oral administration. The serum half-lives in the β-elimination phase of both 10% and 20% solutions after i.v. injection of 10 mg/kg were similar (7.07 ± 1.36 h and 7.16 ± 1.17 h, mean ± SD), whereas the total body clearance and the apparent volume of distribution were higher for the 20% solution. Serum concentrations above 0.5 μg/ml were maintained with both formulations during 12–24 h but were only above 4 μg/ml to 5 h. Intramuscular administration of the 20% solution gave a complete absorption with two rate constants of absorption, a faster (t_1/2a1= 0.27 h) and a slower one (t_1/2a2= 10.90 h) responsible for the delayed elimination half-life after this route of application (t_1/2β= 9.83 ± 1.35 h). Mean serum concentrations reached a maximum level of 3.01 ± 0.72 μg/ml at 4.01 ± 2.84 h and decreased to 0.5 μg/ml between 12 and 24 h. 50 mg/kg given orally with a milk replacer were found to have a mean bioavailability of 46.35%. A mean serum peak level of 4.99 ± 1.37 μg/ml was achieved at 9.16 ± 1.99 h and the mean concentration was still above 0.5 μg/ml after 48 h. The elimination half-life (t_1/2β= 10.66 ± 3.15 h) reflected the slow absorption step (t_1/2a2= 10.15 h) following that responsible for the initial faster absorption (t_1/2a2= 1.99 h). Comparison of the area under the serum curves gave mean values of 117% for tetracycline and of 53% for chlortetracycline relative to oxytetracycline (arbitrarily fixed at 100%) after identical oral dosage of the three tetracyclines. We also propose and discuss a dosage schedule based on minimal inhibitory concentrations of different susceptible pathogens     

Relative bioavailability of microgranulated sulfadimidine in veal calves

The kinetics of free and microgranulated sulfadimidine were compared in milk-fed calves dosed orally (180 mg/kg) in a crossover study. Microgranulation results in delayed absorption of sulfadimidine and poor bioavailability, with the area under the plasma concentration-time curve ( AUC (O-oo)) reduced from 7400 to 3781 μg·h/mL, and maximum plasma concentration ( C _max) reduced from 188.1 ± 39.0 to 84.41 ± 22.6 μg/mL. It is concluded that sulfadimidine microgranulated with long chain fatty acids is not suitable for use in milk-fed calves; the gastrointestinal transit time is too rapid to allow full release of the drug, markedly limiting its bioavailability. In adult animals, or in the young of other animal species in which digesta transit time is slower than in calves, the bioavailability of microgranulated sulfadimidine may be much greater.     

Oral absorption and bioavailability of flumequine in veal calves

The oral absorption and bioavailability of flumequine was studied in 1-, 5- and 18-week-old calves following intravenous and oral administration of different formulations of flumequine (Flumix, Flumix C and pure flumequine). Increasing age had a negative influence on the Cmax after the administration of Flumix, based on a larger VD in the older calves. The Cmax decreased from 5.02 +/- 1.46 micrograms/ml in the first week to 3.28 +/- 0.42 micrograms/ml in the 18th week. Adding colistin sulfate to the flumequine formulation and administring pure flumequine mixed with milk replacer had a negative effect on the Cmax of flumequine after oral administration of 5 and 10 mg/kg body weight. The bioavailability of the orally administered flumequine formulations was 100% in all cases except after the administration of Flumix C, for which it was 75.9 +/- 18.2%. The urinary recovery of flumequine after intravenous injection of a 10% solution varied from 35.2 +/- 2.3% for Group B, to 41.2 +/- 6.3% for Group C. The dosage of 5 mg/kg body weight Flumix twice daily in 1-week-old veal calves is sufficient to reach therapeutic plasma concentrations, based on a MIC value of 0.8 micrograms/ml of the target bacteria. In older calves it is advisable to increase the dosage 7.5 or 10 mg/kg body weight every 12 hours. In combination with colistin sulfate it is also advisable to increase the dosage slightly because of the negative effect of the colistin sulfate on the Cmax of flumequine.     

A survey of abomasal ulceration in veal calves

Abomasal ulceration was found in 264 of 304 commercially reared veal calves at slaughter. The incidence and severity of lesions were greatest in loose housed calves with access to straw and fed milk substitute ad libitum. The majority of lesions were located in the distal pylorus. There was no evidence that the abomasal erosions and ulcers found in the majority of veal calves affected their growth rate or were deleterious to their welfare. It is suggested that pyloric ulceration may be related to the diet of veal calves.     

The pharmacokinetics and residues of clenbuterol in veal calves.

Seven female Brown Swiss calves were used to study the pharmacokinetics of clenbuterol after an effective anabolic dosage of 5 micrograms/kg of BW was given twice daily for 3 wk. Analyses of clenbuterol concentrations in different tissues was done by enzyme immunoassay (EIA). Tissue samples were taken from three calves on the last day of administration and from two more after 3.5 or 14 d of clenbuterol withdrawal. The rate of clenbuterol elimination was dependent on time and tissue. Clenbuterol concentrations in the lung dropped from a mean of 76 ng/g to a level of less than .08 ng/g after 14 d, whereas in the liver the clenbuterol concentrations decreased from 46 ng/g to .6 ng/g within 14 d of withdrawal. Highest levels were always found in the eye: 118 ng/g, 57.5 ng/g, and 15.1 ng/g after 0, 3.5, and 14 d of withdrawal, respectively. These data reveal that different compartments contribute to the elimination of clenbuterol; therefore, concentrations in urine do not follow first order kinetics. An initial rapid decline in the concentration of clenbuterol in urine with a half-life of 10 h is followed by a slower elimination with a half-life of about 2.5 d. Treatments using the anabolic dose of 5 micrograms/kg of BW require longer withdrawal times than the therapeutic dose (.8 micrograms/kg BW).     

Some aspects of the gastrointestinal microflora of veal calves fed different rations: a pilot study

The gastrointestinal microflora of veal calves reared on different diets was studied because the nature of this microflora affects the quality of veal as a result of contamination of carcass surfaces with intestinal contents during slaughter. Diet A consisted of a milk substitute, diet B of milk substitute + straw pellets and diet C of milk substitute + straw pellets + concentrates. In the rumen fluid of calves reared on diet A significantly higher counts of Gram-negative bacteria but lower counts of thermotrophic enterobacteriaceae were found than in calves reared on diets B or C. As for the faecal flora, diets B and C seem to result in significantly lower counts of Gram-negative bacteria and thermotrophic enterobacteriaceae. In 46% of the faecal specimens and 62% of the specimens of rumen fluid from calves fed on milk substitute only, Pseudomonas aeruginosa was isolated in mean counts of 4.1 log cfu/g and 5.2 log cfu/g respectively. P. aeruginosa could not be isolated from any specimen from calves receiving straw pellets. These results indicate that the inclusion of straw pellets in the diet of veal calves may increase the bacteriological safety and keeping quality of veal.     

In vitro transport of carbon in the trachea of veal calves

Summary

Carbon transport was studied in vitro in preparations of trachea and bronchus from veal calves. The mean velocity varied from 4.2 mm/min in the main bronchi to 6.3 mm/min in the ventral trachea. In some locations no transport was observed. Stereomicroscopic evaluation of Alcian blue‐phloxine stained mucosal surfaces revealed differences in the appearance of the mucus layer between locations with and without mucus transport. It is concluded that quality and integrity of the mucus layer play an important role in mucus transport.     

Bone characteristics and body weight of broilers in different husbandry systems

1. An experiment was conducted to determine the effect of husbandry systems on bone characteristics and body weight. Broilers were reared in 5 different husbandry systems: wire mesh (WM) floored cages from 0 to 7 weeks; WM floored cages from 0 to 3 weeks and then transferred to floor pens; plastic mesh (PM) floored cages from 0 to 7 weeks; PM floored cages from 0 to 3 weeks and then transferred to floor pens; floor pens from 0 to 7 weeks.

2. Body weight at 3 weeks of age was affected by the husbandry systems, being greatest for the birds reared in floor pens. At 7 weeks of age, male broilers reared in PM floored cages had the lowest body weight and body weight gain from 4 to 7 weeks.

3. Humerus weight and ash content were affected by cage rearing whereas tibia weight and ash were not. Birds reared in PM cages had shorter tibia and humeri than birds reared in floor pens.