Pharmacokinetics of gentamicin in the calf: developmental changes

The purpose of this study was to determine the pharmacokinetic values for gentamicin in neonatal calves and to compare these values with those in adult cattle (cows). Gentamicin (4 mg/kg of body weight) was administered IV to 7 Holstein bull calves on days 1 (between 12 and 24 hours of age), 5, 10, and 15 after birth, and was administered once IV to 7 Holstein cows. Serum was collected from each animal before administration and at 22 different time intervals from 2 to 400 minutes after injection. Sera were analyzed for gentamicin concentrations. Decay of serum gentamicin concentrations was best described by a 2-compartment pharmacokinetic model. Elimination half-life (t1/2 (beta)) of gentamicin decreased from day 1 (149 minutes) to day 5 (119 minutes), but did not change between days 5 and 15 (111 minutes). Compared with the t1/2(beta) in 1- and 15-day-old calves, the t 1/2 (beta) in cows was shorter (76 minutes). In the calves, apparent volume of distribution (based on total area under the disposition curve) did not change between 1 (393 ml/kg) and 5 (413 ml/kg) days of age, decreased on day 10 (341 ml/kg) and cows day 15 (334 ml/kg), and was markedly smaller than that in cows (140 ml/kg). Total body clearance of gentamicin in cows (1.29 ml/min X kg) was lower than that seen in calves on day 1 (1.92 ml/min X kg) and on day 15 (2.10 ml/min X kg). The decrease in apparent volume of distribution of gentamicin was mirrored by a large decrease in the extracellular fluid volume, as measured by inulin space.(ABSTRACT TRUNCATED AT 250 WORDS)     

Plasma levels of chloramphenicol after oral administration in calves during the first weeks of life

Three experiments were carried out to investigate the mechanisms whereby adequate plasma levels of chloramphenicol may be obtained following oral administration in young calves but not in older animals. In the first experiment, plasma levels of chloramphenicol following an oral dose of 50 mg/kg were followed in six calves, given weekly doses for the first 11 weeks of life. A plasma chloramphenicol level of 5 μg/ml, taken as the minimum therapeutic level, was attained only for a few hours in the 1 week old calves. Thereafter plasma levels decreased very rapidly until the fourth week, and rather more slowly between the fourth and eleventh weeks. At 11 weeks the plasma chloramphenicol level fell to around 0.3 μg/ml, which was the lower limit of sensitivity for the assay technique used. In the second experiment, the same single dose was administered to calves in the twelfth or eighteenth weeks of life which had not previously been exposed to the antibiotic. Plasma levels of 1 μg/ml were barely reached. This suggests that the non-absorbtion of chloramphenicol is unlikely to be related to repeated administration of the antibiotic. In the third experiment, the same single dose was administered orally to two cows. Chloramphenicol could not be detected in the plasma following such administration, and some side-effects were observed in the 48 h following dosing. It is suggested that rumen function may interfere with the absorbtion of chloramphenicol following oral administration to ruminants, even in relatively young animals.     

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.     

Productivity of Crossbred Dairy Cows Suckling their Calves for 12 or 24 Weeks Post Calving

An experiment on restricted suckling of crossbred dairy cows was conducted at the Livestock Research Centre, Tanga in northeast Tanzania. Thirty-six Bos taurus (Holstein Friesian and Jersey) x Bos indicus (East African Zebu) cows were allocated alternately as they calved to suckling their calves for either 12 or 24 weeks after calving. Cows grazed improved pastures and were offered 4 kg concentrate daily. Milking occurred twice daily by hand; calves were allowed to suck residual milk for 30 min following each milking. Calves were also allowed access to grazing and were offered a maximum of 1 kg concentrate daily to 24 weeks of age. Weaning age had no significant effect on lactation milk yield for human consumption, the mean (SE) yield being 1806 (102.0) L and 1705 (129.1) L for 12- and 24-week weaning, respectively. Cows from the two treatments suffered similar losses of live weight and body condition score during lactation and neither group had returned to the original body condition score 40 weeks following calving. Post-partum anoestrous intervals were prolonged. Although not significant, cows suckling calves to 24 weeks had a mean interval to first oestrus extended by 38 days compared with cows suckling calves to 12 weeks. The mean (SE) daily live weight gains of the calves to 52 weeks were 263 (14.1) g/day and 230 (18.1) g/day for calves weaned at 12 and 24 weeks, respectively, such that 12-month weights were 119 (5.6) kg and 110 (7.3) kg, respectively. Twelve-week-weaned calves consumed more concentrate (p<0.05) from 13 to 24 weeks than did 24-week weaned calves. Calculation of residual milk consumption removed by calves from birth to 12 weeks indicated that it accounted for 28%) of total yield. No benefits in cow and calf performance and welfare were found to justify prolonging the suckling period to 24 weeks.     

Chloramphenicol, lincomycin and oxytetracycline disposition in calves with experimental pneumonic pasteurellosis

The effects of pneumonia on the pharmacokinetics of chloramphenicol, lincomycin, and oxytetracycline were evaluated in two-month-old calves. Pneumonia was induced by injection of Pasteurella haemolytica cultures directly through the thoracic wall into each lung. Six days prior to induction of pneumonia, the antibiotics were administered in a single i.v. dose. The antibiotics were administered again 48 (i.v.), 60 and 72 h (i.m.) following injection of P. haemolytica. The pharmacokinetics of chloramphenicol (25 mg/kg) and lincomycin (10 mg/kg) were not significantly different in calves with pneumonia. The hybrid rate constant beta for oxytetracycline was increased in calves with pneumonia from 0.0034 +/- 0.0003/min to 0.0048 +/- 0.0007/min between 2 h and 8 h. Thus the elimination half-life in serum was shortened from 212.4 +/- 20.3 min to 149.3 +/- 19.5 min. In addition, there was an apparent but not statistically significant decrease in K12 with pneumonia. These findings accentuate the need for observance of 12-h dose intervals with oxytetracycline.     

Comparative study of chloramphenicol absorption in calves after oral, intra-ruminal and intra-abomasal administration

The mechanisms responsible for the rapid decline of chloramphenicol plasma levels after oral administration in young calves during their first weeks of life were investigated. Chloramphenicol was administered by stomach tube, to four 2 week old calves on three consecutive days at a dose of 50 mg/kg. The plasma levels increased daily to a peak value on the third day. The minimum therapeutic concentration of 5 μg/ml, however, was barely obtained. Simultaneous estimation of the ruminal contents showed a parallel increase in chloramphenicol concentration. Thus it can be assumed that there is an inefficient absorption of chloramphenicol from the forestomachs of young calves. Chloramphenicol was not metabolized by the ruminal contents until the calves were 9 weeks old. Finally chloramphenicol was administered to 7 week old calves by the intra-abomasal route, intraruminal route and by mouth. Only with the intra-abomasal method could a therapeutically effective level be reached. This indicates that the rapid decline of chloramphenicol plasma levels in calves during their first weeks of life could be attributed to the delayed reticulo-rumen emptying and to inefficient absorption from the forestomachs.     

Effect of age on the acetylation and deacetylation reactions of sulphadimidine and N4- acetylsulphadimidine in calves

Following intravenous (i.v.) or intramuscular (i.m.) adminstration of sulphadimidine (SDM), the pharmacokinetics of SDM and N₄-acetylsulphadimidine (N₄-SDM) were studied in plasma of calves from the first day of life to the age of about 6 months. An obvious age dependency was observed for the elimination half-life (t1/2) of SDM: the first day of life the t1/2 ranged between 13.5 and 17 h, and decreased in approximately 3 weeks to 4–6 h and remained constant from this time. The metabolite N₄-SDM, as a percentage of the total concentration of the sulphonamide measured in plasma of neonatal calves, ranged between 21.6 and 25.5% at the first day of life, declined in 3 weeks to approximately 12.8%, and at 5 till 9 weeks the final percentage was about 6.8%. Following administration of N₄-SDM, the elimination half-life of N₄-SDM was 3 h in an 8-day-old calf declined to 1.4–1.7 h in 4-week-old calves, and was 0.9 h in calves older than 11 weeks. The percentage of SDM (a metabolite of N₄-SDM) in plasma increased with time after injection from 5.5 to 62.8% of the total sulphonamide plasma concentration. This value was age-related. The total body clearance of N₄-SDM was three- to five-fold higher than that of SDM.     

Pharmacokinetics, metabolism and renal clearance of flumequine in veal calves

The pharmacokinetics of flumequine was studied in 1-, 5- and 18-week-old veal calves. A two-compartment model was used to fit the plasma concentration-time curve of flumequine after the intravenous injection of 10 mg/kg of a 10% solution. The elimination half-life (t1/2 beta) of the drug ranged from 6 to 7 h. The Vd beta and ClB of 1-week-old calves (1.07 l/kg, 1.78 ml/min/kg) were significantly lower than those of 5-week-old (1.89 l/kg, 3.23 ml/min/kg) and 18-week-old calves (1.57 l/kg, 3.10 ml/min/kg). After the oral administration of 10 mg/kg of a 2% flumequine formulation mixed with milk replacer, the Cmax was highest in 1-week-old (9.27 micrograms/ml) and lowest in 18-week-old calves (4.47 micrograms/ml). The absorption was rapid (Tmax of approximately 3 h) and complete. When flumequine itself and a formulation containing 2% flumequine and 20 X 10(6) iu of colistin sulphate were mixed with milk replacer and administered at the same dose rate, absorption was incomplete and Cmax was lower. The main urinary metabolite of flumequine was the glucuronide conjugate (approximately 40% recovery within 48 h of intravenous injection) and the second most important metabolite was 7-hydroxy-flumequine (approximately 3% recovery within 12 h of intravenous injection). Only 3.2-6.5% was excreted in the urine unchanged. After oral administration a 'first-pass' effect was observed, with a significant increase in the excretion of conjugated drug. For 1-week-old calves it is recommended that the 2% formulation should be administered at a dose rate of 8 mg/kg every 24 h or 4 mg/kg every 12 h; for calves over 6 weeks old, the dose should be increased to 15 mg/kg every 24 h or 7.5 mg/kg every 12 h. The formulation containing colistin sulphate should be administered to 1-week-old calves at a flumequine dose of 12 mg/kg every 24 h or 6 mg/kg every 12 h.     

Strategies of supplementation of female suckling calves and nutrition parameters of beef cows on tropical pasture

The performance of female calves in creep feeding under different strategies of supplementation and milk production, intake, and digestibility of grazing Nellore and crossbred cows (Nellore?×?Holstein) during the dry-rainy transition season were assessed. Forty-four female beef suckling calves, with initial age between 90 and 150?days and average initial body weight of 117.7?±?4.3?kg, and their respective dams (24 Nellore and 20 crossbred) with average initial body weight of 417.5?±?8.3?kg, were used. The experimental treatments consisted of: control group-mineral mixture only; strategy 1-supplementation from 112?days prior to weaning (0.375?kg/animal/day); strategy 2-supplementation from 112?days prior to weaning, in increasing amounts of 0.15, 0.30, 0.45, and 0.60?kg/animal/day through the four experimental periods, respectively; and strategy 3-supplementation from 56?days prior to weaning (0.750?kg/animal/day). Calves from strategy 1 had greater (P??0.05) for nutrient digestibility among genetic types. It can be concluded that strategies of supplementation that present an equitable distribution of supplement provides greater weight gain in suckling female beef calves. Crossbred cows produce more milk and present greater DMI than Nellore cows. There are no differences in the nutrient digestibility between Nellore and Nellore × Holstein crossbred cows.     

Serum chloramphenicol concentrations in preruminant calves: a comparison of two formulations dosed orally

Serum concentrations of chloramphenicol were determined after oral doses (55 mg/kg body weight) were administered to 7–9 day old Holstein-Friesian calves. Chloramphenicol in an oral solution produced greater serum concentrations than did an equivalent dose of chloramphenicol in capsules ( P <0.005). A second dose of each formulation administered 12 h after the first dose elevated serum chloramphenicol concentrations significantly ( P <0.001). The average serum chloramphenicol concentration exceeded 5 μg/ml of serum 1 h after administration of the solution compared with 4 h for the capsules. Average serum chloramphenicol concentration was greater than 5 μg/ml for at least 12 h after the dose was administered for both formulations. Of the eight calves receiving repeat doses of chloramphenicol, seven (87.5%) developed diarrhea in 76 ± 8.6 h. Six of the eight calves (75%) died during or shortly after the period of chloramphenicol administration.     

Chloramphenicol and the neonatal calf

Pharmacokinetic values and possible toxic effects of chloramphenicol on bone marrow and hematologic and serum chemical values were determined in newborn calves given the drug (IV) once a week or in repeated doses, 12 hours between doses. The rates of elimination for chloramphenicol and antipyrine also were compared. Chloramphenicol also was administered to older calves by IM and subcutaneous routes, with an apparent bioavailability of 50% to 60%. The elimination half-lives for both chloramphenicol and antipyrine were markedly increased in the newborn calf for at least the first 3 to 4 weeks of life. Despite the high and prolonged serum chloramphenicol concentrations in these calves, there was little or no indication of toxic effects. Bone marrow aspirates did not reveal any signs of intoxication such as cytoplasmic or nuclear vacuolation. Marrow cellularity was not recognizably different from the control group.     

Pharmacokinetics of sulfadiazine/trimethoprim in neonatal male calves: effect of age and penetration into cerebrospinal fluid

Sulfadiazine (SDZ)/trimethoprim (TMP; 30 mg of SDZ/TMP/kg of body weight) was given IV to the same 6 male calves at 1, 7, and 42 days of age and to 2 additional calves at 7 days of age. Serum concentrations of SDZ and TMP were best represented by a 2-compartment open model, but in 42-day-old calves, CSF concentrations of both drugs were best represented by a 1-compartment open model with first-order input. Between 1 and 42 days of age, the elimination half-life (t1/2(beta)) of SDZ decreased from 5.7 to 3.6 hours, and total body clearance (CLtot) increased from 1.43 to 1.88 ml/min/kg; the area under the curve (AUC0----infinity) decreased from 291.5 to 225.4 mg/L.h. The distribution coefficient (Vd(area)/kg of body weight) decreased with age, changing from 0.72 to 0.59 L/kg, between 1 and 42 days of age. Therapeutic concentrations of SDZ in serum (greater than 2 micrograms/ml) were maintained for 24 hours in 1-day-old calves and for about 15 hours in 7- and 42-day-old calves. The elimination rate of TMP increased about 9-fold; t1/2(beta) was 8.4, 2.1, and 0.9 hours, respectively, at 1, 7, and 42 days of age. Other values also reflected an increase in TMP elimination rate with age: CLtot increased from 2.8 to 12 to 28.9 ml/min/kg, k13 increased from 0.336 to 0.654 to 1.664/h and AUC0----infinity decreased from 32.8 to 7.9 to 3.1 mg/L.h, respectively. Therapeutic concentrations (greater than 0.1 microgram/ml) were maintained for 15 hours, 8 hours, and about 6 hours in 1-, 7-, and 42-day-old calves, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clearance of penicillin G in the newborn calf

Sodium penicillin G was administered intravenously (4545 IU/kg) to calves on the day of birth (12-24 h old) and at 5, 10, and 15 days of age. Serum was collected at varying intervals for 120 min after injection and analysed for penicillin G. The mean total body clearance (ClB) of penicillin G on the day of birth was 2.98 ml/min/kg compared to 4.83 ml/min/kg at 5 days, 3.11 ml/min/kg at 10 days and 4.65 ml/min/kg at 15 days of age. Clearances at 5 and 15 days were significantly (P less than or equal to 0.05) higher than on the day of birth. The half-life (t1/2 beta), however, did not change significantly over the 15-day period of the study. These results indicate that the newborn calf has an appreciable ability to excrete penicillin G before it is 24 h old, and that total body clearance of the antibiotic increases rapidly in the immediate postnatal period.     

Pharmacokinetic disposition and plasma protein binding (in vitro) of chloramphenicol in Bubalus bubalis I*

Eleven buffalo calves (Bubalus bubalis) of 1-1 1/2 years of age and weighing between 64 and 174 kg were given chloramphenicol at the dose rates of 10 and 20 mg/kg body weight. Pharmacokinetic parameters were determined from the plasma levels. The median elimination half-life was estimated to be 2.95 h and the median volumes of distribution were 1.1667 litres/kg with the 10 mg/kg dose and 0.9699 litres/kg with the 20 mg/kg dose. The median metabolic clearance rates were 288.30 and 234.13 ml/h/kg, respectively. From the average plasma concentrations obtained with the 20 mg/kg i.v. dose, it was considered necessary to repeat the drug by the i.m. route with the same dose (four calves) which resulted in prolonging the therapeutic concentration (> 5 μg/ml) until 18 h. At therapeutic concentrations, about 60% of the drug was bound to plasma proteins. Using the overall elimination rate constant (0.2354 h^-1) and the apparent specific volume of distribution (0.97 litres/kg), different dosage regimens were calculated so as to obtain plasma concentrations (C_p min) of 2, 5 and 10 μg/ml.     

Low phosphorus intakes by beef suckler cows in late pregnancy and early lactation

Two groups each of 10 suckler cows were given a basal diet of oat straw and pressed unmolassed sugar beet pulp for the last 19 weeks of pregnancy and the first 6 weeks of lactation. One group received 0.88 kg extracted soya bean meal (SBM) in pregnancy and 1.03 kg in lactation. The other was given 0.27 kg of a liquid supplement (LS) (containing inter alia urea and phosphoric acid) in pregnancy increasing to 0.33 kg in lactation. Both diets provided about the same amounts of digestible crude protein and about 10 g phosphorus (P) per day in pregnancy and 12 g P per day in lactation. Cows given SBM consumed marginally more straw but there were no differences in total diet digestibility. Cows given LS lost significantly more liveweight but their calves grew equally well. There were indications that cows given LS had slightly higher mean blood inorganic P and lower mean blood calcium (Ca) concentrations. Mean blood inorganic P concentrations were not below 1.4 mmol/l in pregnancy or 1.2 in lactation. There were no signs of reduction in voluntary straw intake or depraved appetite. When transferred to grass with a bull at the end of the experiment all cows were served within 24 days. It is concluded that these amounts of dietary P were adequate over the 25 weeks.     

Effect of restricted suckling on milk yield,composition and flow,udder health,and postpartum anoestrus in grazing Holstein cows

The effect of restricted suckling on milk yield and composition, udder health, and postpartum anoestrus in dairy cows in pasture-based systems, was studied in 32 Holstein multiparous cows and their calves. At calving, each cow–calf pair was randomly assigned to one of two treatments: restricted suckling (RS) of the cows by her own or another calf, twice daily for 30 min or artificial rearing (AR) of the calves with milk obtained from the bulk tank, offered twice a day in buckets. Treatments were applied until week 8 after calving. The diet of the cows consisted of direct grazing in improved pastures, corn silage and a commercial concentrate which was offered at milking. Milk production and composition, udder health, body condition score of the cows, body weight and milk intake of the calves were measured weekly, and the first postpartum ovulation was determined three times a week by ovarian ultrasonography. Cows with RS management had a lower machine-milked milk yield (17.9 vs. 24.8 kg/d), a lower fat percentage (3.21 vs. 4.11%) and 4% fat-corrected milk yield (16.2 vs. 25.7 kg/d), and also a lower average milk flow (1.35 vs. 1.76 kg/min) than cows in the AR treatment. There was no effect of treatment on milk protein percentage or udder health as measured by milk electrical conductivity. The interval from calving to first postpartum ovulation was shorter in the AR cows than in the RS cows (18.5 vs. 21.8 days). The RS calves consumed more milk (7.2 vs. 5.4 kg/d), gained more body weight (0.813 vs. 0.656 kg/d), and had a higher body weight at weaning (84.3 vs. 73.3 kg) than AR calves. Restricted suckling of grazing dairy cows had a negative effect on machine-milked milk yield, fat percentage and 4% fat-corrected milk yield, but had no effect on udder health or on improved weight gain and body weight at weaning of the calves.     

A field trial to evaluate the efficacy of a combined rotavirus-coronavirus/Escherichia coli vaccine in dairy cattle.

A field trial was designed to determine the efficacy of a combination rotavirus-coronavirus/Escherichia coli vaccine on dairy farms in southwestern Ontario. In Part A of the trial, 321 cows on 15 farms were randomly assigned to either vaccination or placebo groups. On eight farms, 50% of the dams were vaccinated, while on the other seven farms, 80% of the dams were vaccinated. In Part B of the trial, 26 farms were randomly assigned to either a total vaccination program or to no vaccination program. Mortality, disease occurrence and weight gains were recorded on all calves for the first two weeks of life. In Part A, 23.5% of all calves were treated in the first two weeks of life, 20.9% were treated specifically for scours and 3.6% of live-born calves died. Enteropathogenic E. coli was identified on 13 of the 15 farms, rotavirus on 11 and coronavirus on ten. At least one of the three potential pathogens was found on every farm. There were no significant differences between calves from placebo-treated and vaccine-treated dams with regard to the proportion treated for all diseases, or for scours, or the proportion which died. Neither were there differences in days to first treatment for all diseases (seven days on average), days to first scour (6.7 days), duration of treatments (3.9 days for all diseases, 3.7 days for scours), or estimated weight gains (0.5 kg/day to 14 days). These results were not altered when the presence or absence of enteropathogenic E. coli, rotavirus or coronavirus on the premises was accounted for.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of different combinations of local anaesthesia,sedative and non-steroidal anti-inflammatory drugs on daily growth rates of dairy calves after disbudding

AIM: To assess the effect of sedation and local anaesthesia (LA) at disbudding, and the addition of meloxicam or ketoprofen treatment, on weight gain in dairy calves following disbudding.

METHODS: Friesian-Jersey cross calves, from four dairy farms, were enrolled when 3–6 weeks old. All calves (n=271) were disbudded by veterinary personnel and randomly assigned to six groups: 136 were disbudded without sedation or LA, of which 31 received 20 mg meloxicam S/C and 75 received 150 mg ketoprofen I/M. A further 135 were disbudded with sedation (0.25 mg/kg xylazine I/M) and LA, of which 30 also received meloxicam and 75 received ketoprofen. Calves were weighed 3 days before, and 15 and 30 days after, disbudding (Day 0). Daily weight gain was analysed using mixed models and ANOVA.

RESULTS: Complete results were obtained from 263 calves. From Day ?3 to Day 15, the growth rate of calves disbudded without pain relief (0.53 (95% CI=0.47–0.60) kg/day) was less that of calves disbudded with some form of pain relief (0.65 (95% CI=0.62–0.68) kg/d; p=0.004). There was no difference between the effect of meloxicam or ketoprofen (p=1.00). An interaction between use of sedation and LA and additional non-steroidal anti-inflammatory drugs (NSAID) meant that NSAID treatment did not increase growth rates in calves disbudded with sedation and LA but did increase growth rates for calves disbudded without pain relief (p<0.05). From Day 16 to Day 30 there was no effect of NSAID treatment on growth rate, but calves receiving LA and sedation grew faster (0.74 (95% CI=0.69–0.80) kg/day) than calves disbudded without LA and sedation (0.66 (95% CI=0.61–0.71) kg/day; p=0.018). From Day ?3 to Day 30, calves disbudded with sedation and LA grew faster (0.71 (95%CI=0.64–0.77) kg/day) than calves disbudded without sedation and LA (0.60 (95% CI=0.55–0.65) kg/day; p=0.011). However, addition of NSAID to sedation and LA made no further difference to growth rates (p=0.69).

CONCLUSIONS: Dairy calves disbudded with no pain relief had slower growth rates than calves receiving pain relief. From Day 15 to 30 calves given no pain relief, or NSAID alone, grew more slowly than those receiving sedation and LA at disbudding. The addition of NSAID treatment to sedation and LA did not further increase growth rates.

CLINICAL RELEVANCE: This study adds to the evidence that pain management when disbudding is beneficial for calf productivity as well as calf welfare.     

The impact of cow nutrition in the dry period on colostrum quality and immune status of calves

The objective of the study was to evaluate the effect of energy contents in a dry period diets in "7+1" feeding strategy of dry cow including 7 weeks of the dry period (far-off) and 1 week of a close-up period, on colostrum quality and the immune status of calves. Forty Holstein multiparous cows were dried at 56d before the expected date of calving and were assigned to the higher energy diet group (HE; 0.69 UFL/kg DM, NDF 52% DM), or the lower energy diet group (LE; 0.61 UFL/1kg DM, NDF 56% DM). From -7d to the expected calving date up to 21 d of lactation, all cows were fed the same fresh, lactation diet. Samples of colostrum were collected within 2h after parturition and its density, dry matter content and concentrations of immunoglobulins, fat, protein, lactose, urea and somatic cell counts were measured. Calves were weighed 2 h after calving and on the 21d of life. On 3d and 21d of calves' life blood samples were collected and the concentration of IgG, IgA, IgM, insulin-like growth factor 1 (IGF-1) as well as total protein and albumin concentrations were determined. Treatments had no significant effect on composition of colostrum and serum immunoglobulins and IGF-1 concentration. In both groups the weight of calves at birth was similar, still daily body weight gain during 21 day of rearing period in HE group was higher than in the LE group (P=0.05).     

Pharmacokinetics, metabolism and renal clearance of sulphatroxazole in calves and cows

The pharmacokinetic analysis of plasma concentration--time curves after a single i.v. dose of 20 mg/kg sulphatroxazole (STZ) to calves and cows revealed a small distribution volume of STZ (mean VD(area) = 0.22-0.26 l/kg) and an age dependent elimination (mean t1/2 6.6-18.8 h). In calves and cows, STZ was extensively metabolized into the N4-acetyl and 5-hydroxy derivatives. In the plasma of calves, the N4-acetyl metabolite (N4-STZ) was present in greater amounts than the hydroxy metabolite (5-OH-STZ), while in cows' plasma concentration of these two metabolites were similar. In the milk of dairy cows STZ concentrations paralleled those of the metabolites and were approximately 21 times lower than corresponding plasma concentrations. The mean plasma protein binding of STZ and its metabolites ranged from 36.4 to 82.5% of total concentration. The N4-STZ derivative was excreted by tubular secretion; the 5-OH-STZ and the parent compound, mainly by glomerular filtration. In calves the majority of STZ administered was excreted as N4-STZ (40-52%), while in cows the parent drug dominated the urinary excretion (36%).