White Veal Calves Research Articles

Short communication: Herd-level analysis of antimicrobial use and mortality in veal calves: Do herds with low usage face higher mortality?

The veal calf sector fears that a too-rapid and large decrease in antimicrobial use (AMU) as demanded by European authorities would increase mortality, causing economic and welfare issues. To determine whether this concern is justified, the relationship between AMU (total and different classes) and mortality in dairy-type white veal calves, managed by 2 large veal companies, was explored. A retrospective cohort study was performed on electronically collected antimicrobial consumption and mortality data from the largest Belgian veal practice during the period 2014 to 2016. Mixed linear [mortality (%) as continuous outcome] and generalized linear mixed models with binary outcome for event and trial approach were built to identify factors associated with mortality. Data consisted of 76 production cycles from 29 farms managed by 2 veal companies (1 and 2) and covering 45,001 calves. Average AMU was 30.1 ± 10.4 defined daily doses for animals per year (± standard deviation) and was higher in veal company 2 than in veal company 1 (35.9 ± 9.3 and 22.4 ± 5.7 defined daily doses for animals per year, respectively). In contrast, mean mortality was lower in veal company 2 (2.3 ± 1.4%) than in veal company 1 (4.1 ± 1.4%). Both models showed a positive association between AMU and mortality in veal company 1 and no association in veal company 2. The final linear model identified increasing herd size and the use of third- or fourth-generation cephalosporins as risk factors for mortality and the use of long-acting macrolides as a protective factor. The final logistic model identified an increased mortality risk with increased use of third- or fourth-generation cephalosporins and sulfonamides-trimethoprim and decreased mortality when using long-acting macrolides. Based on these data, at the current levels of AMU in Belgian veal calves, an increase in mortality when reducing AMU could not be evidenced. Differences in herd size and factors other than AMU likely better explain why one veal company faces almost double the mortality of another one. Abandoning the use of long-acting macrolides might have negative consequences for mortality under the current state of the industry. The most ethical way to further reduce AMU in veal calves is likely simultaneously monitoring AMU and animal welfare parameters, starting with, but not limited to, mortality.

Using routinely collected data to evaluate risk factors for mortality of veal calves

From 2009 to 2012 a gradual increase in on-farm mortality of Dutch veal calves was observed. In 2012, the cattle industry decided that more information was needed on risk factors for mortality in both veal herds and herds of origin to enable implementation of risk mitigating measures. Routinely collected data were available from seven different data sources and contained information from 2.4 million white veal calves that were fattened in the period between 1 January 2011 and 30 June 2014. Survival analysis techniques (Kaplan-Meier), multilevel Poisson and multilevel Logistic regression models were applied to analyse the data. Two different models were assembled in which risk factors for veal calf mortality in respectively veal herds and herds of origin were identified. Univariable and multivariable regression techniques were used to detect risk factors significantly associated with mortality of veal calves during the fattening period. During the study period, the mean mortality was 4.9% per production cycle. The probability to die was highest during the first weeks after arrival in the veal herds and declined thereafter. Important risk factors included a veal herds with a higher use of antimicrobials, hair colour as proxy for breed, certain countries of origin, veal herd management with a limited amount of supplied feed and a not having an all-in / all-out system. A higher body weight at arrival in the veal herd was associated with lower mortality as well as veal calves that were fed an above median amount of milk, roughage and concentrates. From the calves that were fattened during the study period, observations of 1.1 million calves originated from the Netherlands and were available to study risk factors for veal calf mortality associated with the herd of origin. Important risk factors included purchase, herds with high mortality rates in the quarter in which the calf was born, fast growth in herd size, high cattle replacement rates and a higher antibiotic use in the quarter of birth. Calves that originated from herds that were certified BVD-free, Salmonella-unsuspected or Paratuberculosis-unsuspected, had a lower odds to die during the subsequent fattening period in a veal herd. Veal calf mortality was influenced by risk factors at the herd of origin as well as at veal herds. Adequate collaboration between the different industries is necessary to optimize veal calf management leading to a reduction in veal calf mortality during the fattening period.

Quantitative and qualitative analysis of antimicrobial usage in white veal calves in France

The development of antimicrobial resistance has made it necessary to measure antimicrobial usage in animal production sectors. France is a major European producer of white veal calves, but few data were previously available for that sector, even though these young animals are particularly susceptible to infection and considered as a reservoir of antimicrobial resistance. A cross-sectional study was conducted on 186 batches of French calves to estimate the exposure of white veal calves to antimicrobials and identify the potential risk factors related to antimicrobial usage. An indicator of calf exposure was calculated as a count of the number of antimicrobial treatments per calf. The indicator was based on veterinary prescriptions (products, quantity dispensed and dosage prescribed) and the estimated weight of calves at treatment, using the dates of treatment collected from farm registers.The study showed that calves were exposed to an average of 8.55 antimicrobial treatments (SD: 2.21, range: 2.75–15.86) over the five to six months of the fattening process. Group treatments were predominant (95.8%) and administered by the oral route. The “starting treatments”, given during the first two weeks of the fattening period, were administered systematically (to all the calves in all the farms) and accounted for a third of all treatments. Tetracyclines, polypeptides and macrolides were the most widely used antimicrobials, with respectively 4.32, 1.59 and 1.01 treatments per calf. Only rare uses of 3rd and 4th generation cephalosporins and fluoroquinolones, considered as critically important in human medicine, were reported.Despite low variability of exposure between farms, a linear mixed-effects model highlighted a higher variability between farmers (ICC=0.14) or veterinarians (ICC=0.12), than between integrators (ICC=0.06). The number of calves per pen, introduced as a fixed effect in the model, was also significant: calves housed in pens of 6–10 and fed in buckets had on average 2.55 more antimicrobial treatments per calf than calves housed in pairs with the same feeding system. The model also highlighted an increase of 1.48 treatments per calf for farms with more than five percent of mortality, versus those with two percent or less.The present study showed that antimicrobial treatments are numerous in veal calf fattening farms, particularly at the arrival of the animals. Taking into account the development of resistance to antimicrobials, the necessity and the effectiveness of some of these treatments should be re-evaluated.

Environmental survival of Mycoplasma bovis on a white veal farm

Mycoplasma bovis is an emerging cause of bovine respiratory disease (BRD), particularly in intensive feedlots where disease is mainly spread by aerosol route over close distances. The present study aimed...

Antimicrobial resistance in commensal Escherichia coli in veal calves is associated with antimicrobial drug use.

The aim of this study was to determine the association between farm management factors, including antimicrobial drug usage, and resistance in commensal Escherichia coli isolates from the faeces of white veal calves. Ninety E. coli isolates from one pooled sample per farm (n = 48) were tested for their phenotypical resistance against amoxicillin, tetracycline, cefotaxime, ciprofloxacin and trimethoprim/sulfamethoxazole (TMP/SMX). Logistic regression analysis revealed the following risk factors (P < 0·05); farmer wearing the same work clothes for several days [ciprofloxacin, odds ratio (OR) 2·6; tetracycline, OR 2·4], administration of trimethoprim-sulfonamide combinations (TMP/SMX, OR 3·0; amoxicillin, OR 3·1; tetracycline, OR 2·6), ⩾0·3 animal daily dosage per production cycle (ADD/pc), quinolones (ciprofloxacin, OR 2·8), ⩾1·3 ADD/pc, penicillins (ciprofloxacin, OR 3·3; tetracycline, OR 3·4), 20-40 ADD/pc, tetracyclines (tetracycline, OR 3·2) and >40 ADD/pc, tetracyclines (tetracycline, OR 13·1; amoxicillin, OR 6·5). In this study antimicrobial resistance in commensal E. coli was mainly associated with antimicrobial drug use.

Prevalence and bacterial colonisation of fundic ulcerations in veal calves

The European veal industry is specialised in raising surplus dairy calves on a low iron milk diet to obtain white meat. Next to Holstein-Friesian (HF) dairy calves, also beef calves...

Impact of respiratory disease, diarrhea, otitis and arthritis on mortality and carcass traits in white veal calves

BackgroundLittle is known on the effects of common calf diseases on mortality and carcass traits in the white veal industry (special-fed veal), a highly integrated production system, currently criticized for the intensive pro- and metaphylactic use of antimicrobials. The objective of the present study was to determine the impact of bovine respiratory disease (BRD), diarrhea, arthritis and otitis on the economically important parameters of mortality, hot carcass weight (HCW), carcass quality, fat cover and meat color. For this purpose, a prospective study on 3519 white veal calves, housed in 10 commercial herds, was conducted. Case definitions were based on clinical observation by the producers and written treatment records were used.ResultsCalves received oral antimicrobial group treatments in the milk during 25.2% of the production time on average. With an increasing percentage of the production cycle spent on oral antimicrobials, HCW reduced, whereas the odds for insufficient fat cover or an undesirable red meat color both decreased. Of the calves, 14.8%, 5.3%, 1.5% and 1.6% were individually diagnosed and treated for BRD, diarrhea, arthritis and otitis, respectively. Overall, 5.7% of the calves died and the mortality risk was higher in the first weeks after arrival. Calves that experienced one BRD episode showed a 8.2 kg reduction in HCW, a lower fat cover and an increased mortality risk (hazard ratio (HR) = 5.5), compared to calves which were not individually diagnosed and treated for BRD. With an increasing number of BRD episodes, these losses increased dramatically. Additionally, calves, which experienced multiple BRD episodes, were more likely to have poor carcass quality and an undesirable red meat color at slaughter. Arthritis increased the mortality risk (HR = 3.9), and reduced HCW only when associated with BRD. Otitis did only increase the mortality risk (HR = 7.0). Diarrhea severely increased the mortality risk (HR = 11.0), reduced HCW by 9.2 kg on average and decreased carcass quality.ConclusionsDespite the massive use of group and individual treatments to alleviate the most prevalent health issues at the fattening period, the effects of BRD, diarrhea, otitis and arthritis on survival and performance are still considerable, especially in cases of chronic pneumonia with or without arthritis. Controlling calf health by effective preventive and therapeutic strategies and in particular the prevention of chronic BRD is key for the profitability of veal operations.

Scientific Opinion on the welfare of cattle kept for beef production and the welfare in intensive calf farming systems.

Information given in previous Opinions “Welfare of cattle kept for beef production” (SCAHAW, 2001) and “The risks of poor welfare in intensive calf farming systems” (EFSA, 2006) is updated and recent scientific evidence on the topics reviewed. Risks of poor welfare are identified using a structured analysis, and issues not identified in the SCAHAW (2001) beef Opinion, especially effects of housing and management on enteric and respiratory diseases are reviewed. The Opinion covers all systems of beef production, although the welfare of suckler cows or breeding bulls is not considered. The Chapter on beef cattle presents new evidence and recommendations in relation to heat and cold stress, mutilations and pain management, digestive disorders linked to high concentrate feeds and respiratory disorders linked to overstocking, inadequate ventilation, mixing of animals and failure of early diagnosis and treatment. Major welfare problems in cattle kept for beef production, as identified by risk assessment, were respiratory diseases linked to overstocking, inadequate ventilation, mixing of animals and failure of early diagnosis and treatment, digestive disorders linked to intensive concentrate feeding, lack of physically effective fibre in the diet, and behavioural disorders linked to inadequate floor space, and co‐mingling in the feedlot. Major hazards for white veal calves were considered to be iron‐deficiency anaemia, a direct consequence of dietary iron restriction, enteric diseases linked to high intakes of liquid feed and inadequate intake of physically effective fibre, discomfort and behavioural disorders linked to inadequate floors and floor space.

Livestock-associated MRSA prevalence in veal calf production is associated with farm hygiene, use of antimicrobials, and age of the calves

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) is highly prevalent in pork and veal production chains. In this study, we used data from a cross-sectional survey on 2151 calves from 102 veal calf farms to identify potential risk factors, with the goal of reducing MRSA prevalence by developing intervention strategies. Overall, calves from rose veal farms had a lower risk of LA-MRSA carriage than calves from white veal farms. Data were analysed separately for white and rose veal calves, because management systems of the two production chains were largely different. Group treatment with antimicrobials appeared to be a risk factor for MRSA carriage in white veal calves in univariate analyses, but was not included in the final multiple regression model that included age of the calves and rodent control. Number of start treatment days was positively associated with LA-MRSA carriage in rose veal calves, and was the only risk factor selected for the final multiple regression model for this group. Interpretation of the results from this cross-sectional study is complicated by the strong correlation between antimicrobial use, LA-MRSA carriage and age of the calves. Other age-related factors may be more influential. However, taken together these findings emphasize the need for prudent use of antimicrobials, and point to improvement of farm hygiene as a control measure.

Prospective study on quantitative and qualitative antimicrobial and anti-inflammatory drug use in white veal calves

To document and quantify drug use in white veal calves, an intensive livestock production system where multidrug resistance is abundantly present. Drug consumption data were prospectively collected on 15 white veal production cohorts (n = 5853 calves) in Belgium (2007-09). Treatment incidences (TIs) based on animal defined daily dose (ADD), prescribed daily dose (PDD) and used daily dose (UDD) were calculated. Risk factors were identified by linear regression. The average TI(ADD) of antimicrobial treatments was 416.8 ADD per 1000 animals at risk. Predominantly, oral group antimicrobial treatments were used (95.8%). Of the oral group antimicrobial treatments, 12% and 88% were used for prophylactic or metaphylactic indications, respectively. The main indication for group and individual drug use was respiratory disease. The most frequently used antimicrobials (group treatments) were oxytetracycline (23.7%), amoxicillin (18.5%), tylosin (17.2%) and colistin (15.2%). Deviations from the leaflet dosage recommendations were frequently encountered, with 43.7% of the group treatments underdosed (often oxytetracycline and tylosin to treat dysbacteriosis). In 33.3% of the oral antimicrobial group treatments a combination of two antimicrobial preparations was used. Smaller integrations used more antimicrobials in group treatments than larger ones (P < 0.05); an integration is defined as a company that combines all steps of the production chain by having its own feed plant and slaughterhouse and by placing its calves in veal herds owned by producers that fatten these calves for this integration on contract. Producers used higher dosages than prescribed by the veterinarian in cohorts with a single caretaker (P < 0.01). The present study provided detailed information on the intensive antimicrobial use in the white veal industry. Reduction can only be achieved by reducing the number of oral group treatments.

Longitudinal study on morbidity and mortality in white veal calves in Belgium

BackgroundMortality and morbidity are hardly documented in the white veal industry, despite high levels of antimicrobial drug use and resistance. The objective of the present study was to determine the causes and epidemiology of morbidity and mortality in dairy, beef and crossbred white veal production. A total of 5853 calves, housed in 15 production cohorts, were followed during one production cycle. Causes of mortality were determined by necropsy. Morbidity was daily recorded by the producers.ResultsThe total mortality risk was 5,3% and was significantly higher in beef veal production compared to dairy or crossbreds. The main causes of mortality were pneumonia (1.3% of the calves at risk), ruminal disorders (0.7%), idiopathic peritonitis (0.5%), enterotoxaemia (0.5%) and enteritis (0.4%). Belgian Blue beef calves were more likely to die from pneumonia, enterotoxaemia and arthritis. Detection of bovine viral diarrhea virus at necropsy was associated with chronic pneumonia and pleuritis. Of the calves, 25.4% was treated individually and the morbidity rate was 1.66 cases per 1000 calf days at risk. The incidence rate of respiratory disease, diarrhea, arthritis and otitis was 0.95, 0.30, 0.11 and 0.07 cases per 1000 calf days at risk respectively. Morbidity peaked in the first three weeks after arrival and gradually declined towards the end of the production cycle.ConclusionsThe present study provided insights into the causes and epidemiology of morbidity and mortality in white veal calves in Belgium, housed in the most frequent housing system in Europe. The necropsy findings, identified risk periods and differences between production systems can guide both veterinarians and producers towards the most profitable and ethical preventive and therapeutic protocols.

Prevalence of gastrointestinal disorders recorded at postmortem inspection in white veal calves and associated risk factors

The study aimed at assessing the prevalence of poor rumen development, presence of rumen plaques, rumen papillae hyperkeratinization, and abomasal lesions in veal calves and to investigate risk factors for their occurrence at the farm level. Within a wide cross-sectional study, a sample of 170 veal farms representative of the European veal meat production systems was considered in the 3 major producing countries (99 in the Netherlands, 47 in France, and 24 in Italy). An average of 59±10 (SD) rumens and abomasa belonging to calves from a single batch per farm were inspected at the abattoir by trained observers to assess the incidence of these gastrointestinal disorders. Potential risk factors for their occurrence related to farm management, housing, and to the feeding plan were obtained by a questionnaire submitted to the stockperson. Prevalence of poor rumen development (almost no papillae present), rumen plaques, and hyperkeratinization were 60.4, 31.4, and 6.1% of rumens, respectively, whereas abomasal lesions in the pyloric area were recorded in 74.1% of abomasa. Independent variables related to the feeding system confirmed to be the main risk factors for the occurrence of gastrointestinal disorders in veal calves. However, additional risk sources for each given problem were identified among housing and management variables. The provision of a low amount of solid feed (≤50kg of dry matter/head per cycle) was a relevant risk for rumen underdevelopment. Rumen wall alterations (plaques and hyperkeratinization) and abomasal lesions were instead associated with the administration of large quantities of solids (151–300kg of dry matter/head per cycle) in calves receiving milk replacer during the entire fattening cycle. Among the types of solid feed, cereal grain acted as a preventive measure for low rumen development, whereas it was a risk factor for the occurrence of rumen plaques, papillae hyperkeratinization, and abomasal lesions. Some housing and management options adopted to improve veal calf welfare (i.e., higher space allowance and use of heating) were associated with lower risk for gastrointestinal disorders.

ESCHERICHIA COLI O157 IN WITHE VEAL CALVES CARCASSES

During 2006 one hundred and three white veal calves slaughtered at an abattoir in Isernia (Italy) were examined for E. coli O157 intestinal carriage and carcass contamination, using Immuno-Magnetic Separation (IMS) and multiplex PCR. Faecal material before slaughtering and carcass samples, using sponge-bag, were collected. E. coli O157 isolates were found in 10 (9,71%) faecal and 9 (8,7%) carcass samples. PCR analysis showed that all the strains from faecal and from carcass samples carried eaeA, hlyA and stx2 genes, while five strains stx1 gene. The results confirm that the slaughter practices can largely influence the rate of E. coli O157 carcasses contamination and suggest that white veal calves meat could be an important risk for human health.

Escherichia coli O157:H7 and other Shiga toxin-producing E. coli in white veal calves

The aims of the study were to determine the prevalence of enterohemorrhagic Escherichia coli O157:H7 (EHEC O157) and other Shiga toxin-producing E. coli (STEC) in feces of white veal calves in an operation in Ontario, to evaluate exposure of the calves to EHEC O157, and to investigate the milk replacer diet and antimicrobial resistance as factors that might influence the prevalence of EHEC O157. Feces from three cohorts of 20–21 calves were collected weekly for 20 weeks and processed for isolation of EHEC O157:H7 and detection of STEC by an ELISA. Exposure to EHEC O157 was also investigated by measuring IgG and IgM antibodies to the O157 lipopolysaccharide (O157 Ab) in sera by ELISA. The prevalences of EHEC O157 were 0.17% of 1151 fecal samples and 3.2% of 62 calves, and for STEC were 68% of 1005 fecal samples and 100% of 62 calves. Seroconversion to active IgG and IgM O157 Ab responses in some calves was not associated with isolation of EHEC O157. The milk replacer contained low levels of antibodies to EHEC antigens and without antimicrobial drugs, it did not inhibit the growth of EHEC O157 in vitro. Two E. coli O157:H7 that were isolated were totally drug sensitive whereas 60 commensal E. coli isolates that were examined were highly resistant. Antibodies in milk replacer that might be protective in vivo, and susceptibility to antimicrobial agents in the milk replacer may contribute to the low prevalence of EHEC O157 in white veal calves.

Control of the bioavailability of iron in heavy veal production by different feeding management systems: Use of Ca–EDTA as an iron chelating agent

Seventy male dairy black and white veal calves were allotted to five treatment groups: MILK, in which animals received exclusively milk replacer; MIX, in which animals received concentrates ad lib and milk replacer during the whole period, more specifically, 750 g of milk powder d−1 starting at week 4; GRAIN, in which animals received milk replacer during the first 4 wk and concentrates during the whole period; MIX+EDTA and GRAIN+EDTA, in which animals received the same diet as their respective controls plus 15 mg of EDTA mg−1 of Fe in the concentrates of the diet starting at week 4 of the experiment. MILK–fed calves had better average daily gains (ADG) than MIX–EDTA–fed or GRAIN+EDTA–fed calves (P &lt; 0.001). However, GRAIN+EDTA–fed calves had lower ADG than GRAIN calves (P &lt; 0.01). The EDTA treatments were without effect (P &gt; 0.10) on feed efficiency and EDTA did not affect N digestibility (P &gt; 0.10) or Fe retention (P &gt; 0.10). Treatments with EDTA lightened the color of the meat (P &lt; 0.01), reduced myoglobin and reduced muscle Fe (P &lt; 0.01). Diet reduced carcass fatness in the following decreasing order: MILK, MIX, GRAIN. Treatments with EDTA had no effect on carcass composition. Key words: Veal, milk-replacer, grain, meat color, chelator

Dietary supplements of folic acid: blood and growth responses of white veal calves

The effects of dietary supplements of folic acid on growth performances and haematological and hepatic variables of white veal calves were studied in 90 young dairy calves. From the age of approximately 2 weeks, they received twice daily 0, 4 or 16 mg of supplementary folic acid added to the milk replacer. They were fed exclusively milk replacer for 105 days. Supplements of folic acid increased serum ( P⩽0.05) and red blood cell ( P⩽0.05) folate concentrations, and slowed the decrease with age of haemoglobin and packed cell volume ( P⩽0.05). The addition of 4 or 16 mg of folic acid twice daily to the milk replacer increased hepatic folates by a factor of 39.5% and 57.4%, respectively, as compared to controls ( P⩽0.05). Folic acid improved growth ( P⩽0.05), but had no effect on feed intake ( P>0.05). Time required to reach 180 kg decreased linearly as supplements of folic acid increased ( P⩽0.05). Calves receiving 0, 4 or 16 mg of folic acid twice daily reached 180 kg in 95.3±2.7, 89.9±1.l, or 88.7±1.4 days, respectively. It was concluded that dietary supplements of folic acid improved haematological variables and shortened the rearing period of white veal calves without increasing their feed intake.

The effect of dietary electrolyte balance on blood parameters and the performance of veal calves

Ninety-six Dutch red and white male veal calves were used in a 19-week feeding trial with 5 diets differing in dietary electrolyte balance (dEB = Na + K - Cl). These dEBs were 6.4, 15.7, 25.0, 34.4 and 43.8 meq 100 g −1 of feed for Diets 1, 2, 3, 4 and 5, respectively. These balances were achieved by adding NH 4Cl (1.0 or 0.5%) or sodium citrate dihydrate (2.51 or 1.75%) to a milk replacer. With Diets 2, 3 and 4 the growth rate and the feed conversion ratio were not significantly different ( P > 0.05). Compared to the mean results obtained with the 3 other diets, the low-dEB (1) and the high-dEB (5) diets caused a mean reduction of 8% in live weight gain and a mean increase of 5% in feed conversion ratio. There were no significant differences ( P > 0.05) among treatments in carcass classification characteristics. The pH, bicarbonate level, pCO 2 and base excess of the blood were significantly decreased, while the blood chloride level was increased ( P < 0.05) in animals which received Diet 1. The haemoglobin, sodium and potassium levels and the haematocrit value of the blood were not affected by dEB. There were no differences ( P > 0.05) in the blood parameters between animals fed Diets 2, 3, 4 or 5.

BLOOD SERUM CONCENTRATIONS OF FOLATES AND VITAMIN B12 DURING GROWTH PERIOD OF WHITE VEAL CALVES

Variations of hemoglobin, hematocrit, folates and vitamin B12 concentrations in blood serum were studied during the rearing period of 62 rapidly growing (1.6 kg d−1) white veal calves. The animals were fed exclusively with milk replacers during the 110 d rearing period. Hemoglobin and hematocrit decreased linearly with time (P &lt; 0.0001). There was an age effect (P &lt; 0.0001) on serum concentrations of vitamin B12 and folates during the rearing period. The serum concentrations of vitamin B12 increased during the first 3 wk from 214.8 pg mL−1 to 422.6 pg mL−1 and then were stable until the 13th week of the rearing period. Serum concentrations of folates decreased during the 3 wk from 11.3 ng mL−1 to 5.1 ng mL−1 and then increased to reach a stable concentration of about 14 ng mL−1 from 6 wk to the end of the rearing period. Males had significantly lower serum folates concentrations than females (P &lt; 0.0001) but their serum profiles during the rearing period were similar. Further studies will be necessary to elucidate the consequences of a decrease in serum folates during the starting period on the growth performance of white veal calves. Key words: White veal calves, blood serum folates, vitamin B12