USDA regulation of residues in meat and poultry products

The National Residue Program conducted by the Food Safety and Inspection Service (FSIS) of the USDA includes a comprehensive testing program for residues of pesticides, drugs and other chemical contaminants in meat and poultry. Prevention strategies encourage producers to adopt quality control measures in their production management to prevent illegal residues in food. These activities have been effective in reducing the occurrence of violative residues and the potential for adverse health effects. Overall, the number of domestic monitoring samples containing violative residues is low-about 1% of samples tested. Violative residues are found less frequently in poultry than in livestock. More occur in swine than in other species; the least number occur in fed cattle and broilers. Testing results over the last 10 yr show that most drugs and pesticides used to enhance agricultural productivity are not causing a residue problem in meat and poultry. However, the FSIS cannot be complacent about its program achievements. Unacceptably high incidences of violative residues of certain drugs, namely, sulfonamides and antibiotics, still occur in particular production classes. For example, the incidence of violative sulfonamide residues in liver samples from swine slaughtered in 1985 was about 6%, with significant differences between geographical areas. An estimated 2.5% of market hogs had violative sulfamethazine residues in the muscle tissue. The FSIS is taking steps to correct this and other residue problems by strengthening the link between residue detection and enforcement and by expanding its analytical capability to monitor for residues.     

Sulfamethazine residues in swine

Two possible causes of violative sulfonamide residues in swine were studied. To determine if sulfamethazine accumulated in the tissues of swine when the drug was administered in feed, the rates of plasma drug disappearance following a single oral dose and continuous feeding of the drug were compared. The rate of plasma drug disappearance was not significantly different (α= 0.05) when the two methods of drug dosing were compared. When feed containing 2 μg sulfamethazine/gm was fed to swine during a 7—day period preceding slaughter, the animal's liver contained violative residues. Violative concentrations of sulfamethazine were detected in the livers, kidneys, and skeletal muscle of swine which consumed feed containing 8 μg sulfamethazine/gm.     

Tissue disposition and depletion of penicillin G after oral administration with milk in unweaned dairy calves

OBJECTIVE: To determine tissue depletion of penicillin G in calves after oral ingestion with milk replacer and estimate a withdrawal period. DESIGN: Longitudinal controlled trial. ANIMALS: 26 Holstein calves. PROCEDURE: Once daily, 24 calves were fed milk replacer containing procaine penicillin G (0.68 mg/kg [0.31 mg/lb] of body weight); 2 calves served as controls. After 1 feeding, 12 calves were euthanatized in groups of 3 each 4, 6.5, 9.5, and 13 hours after feeding. After 14 days, 12 calves were euthanatized in groups of 3 each 4, 6.5, 9.5, and 13 hours after the final feeding. Concentrations of penicillin G were determined in tissues, blood, and urine by use of high-performance liquid chromatography. RESULTS: Penicillin G was not detected in muscle samples of treated calves. The highest concentrations of penicillin G in plasma, kidney, and liver were 13 ng/ml, 92 ng/g, and 142 ng/g, respectively. Thirteen carcasses had violative drug residues; 12 had violative residues in the liver only, and 1 had violative residues in the liver and kidney. A 21-hour withdrawal period was estimated. CONCLUSIONS AND CLINICAL RELEVANCE: Liver had the highest concentration of penicillin G and was most likely to have violative residues. Feeding calves milk containing penicillin G has the potential to cause violative drug residues in tissues. It is recommended to observe an appropriate withdrawal time prior to slaughter if calves are fed milk from cows treated with penicillin G.     

Plasma/muscle ratios of sulfadimethoxine residues in channel catfish (Ictalurus punctatus)

Channel catfish ( n = 84) maintained at a water temperature of 27°C were used in a feeding study to determine the plasma to muscle concentration ratios of sulfadimethoxine (SDM) and 4-N-acetylsulfadimethoxine residues. Sulfadimethoxine medicated feed was provided free choice at 42 mg SDM/kg body weight once daily for 5 days and the plasma and muscle concentrations of SDM were determined at selected withdrawal times (6, 12, 24, 48, 72, and 96 hours) following the last dose. Considerable variation in total SDM tissue concentration among fish within a sampling period was observed. For fish ( n = 12) at six hours post-dose, total SDM concentrations ranged from 1.4–24.8 μg/mL and 0.6–12.6 μg/g, with mean total SDM concentrations of 9.1 μg/mL and 5.3 μg/g for plasma and muscle, respectively. However, a mean plasma:muscle concentration ratio of 1.8:1 ± 0.3:1 was obtained over all concentrations and sampling periods. The plasma:muscle 95% t distribution interval for individual fish was 1.2:1 to 2.4:1. A correlation coefficient of 0.967 was obtained for the relationship between plasma and muscle total SDM concentration among individual fish ( n = 25). Results of this study indicate that plasma total SDM concentration may be used to identify samples containing violative SDM muscle residue. No fish contained total SDM muscle residues greater than the FDA tolerance (0.1 μg/g) by 48 hours following the final dose.     

Evaluation of certification in the Milk and Dairy Beef Quality Assurance Program and associated factors on the risk of having violative antibiotic residues in milk from dairy farms in Michigan

OBJECTIVE: To determine whether certification in a Milk and Dairy Beef Quality Assurance Program (MDBQAP) was associated with a reduced risk of having antibiotic residues in milk and to define specific management factors that may have predisposed dairy farms to having violative antibiotic residues in milk. SAMPLE POPULATION: 124 dairy farms in Michigan that had > 1 violative residue in milk during 1993 and 248 randomly selected control farms in Michigan that did not have violative residues in milk during 1993. PROCEDURE: A pretested structured questionnaire was mailed to case and control farms. A conditional multivariate logistic regression model was developed to determine risk factors associated with having a violative antibiotic residue in milk. RESULTS: Certification in the MDBQAP did not significantly reduce the risk of having a violative antibiotic residue. Annual treatment of > 10% of a herd for metritis was associated with a reduced risk of having a violative residue. Evidence suggested that a routine request for a milk processor to perform residue testing was associated with a decreased risk of having had a violative antibiotic residue, but routine on-farm residue testing was associated with an increased risk of having had a residue. CONCLUSIONS AND CLINICAL RELEVANCE: MDBQAP certification was associated, although not significantly, with a reduced risk of having violative antibiotic residues in milk. Risk factors significantly associated with violative antibiotic residues are addressed by various critical control points in the MDBQAP and may be indicators for strengths and weaknesses of MDBQAP.     

市售猪肉及其组织中"瘦肉精"残留调查

采用德国r-Biopharm拜发公司试剂盒，用竞争性EUSA法对某市13个菜场共抽取40份瘦肉、30份猪肝、18份猪肾脏、30份猪肺、15份猪骨和30份猪血、30份猪毛，总计样品进行了瘦肉精残留检测。结果表明，在抽检的193份样品中共有38份瘦肉精含量大于1．0ng／g，占总数的19．7％，其中猪肝与猪毛的检出率最高。同时在瘦肉精含量大于1．0ng／g的样品中抽取9份，用GC／MS／MS法确证，结果与ELISA法相符。     

Prevalence of streptococcus bovis in racing pigeons

Summary

The prevalence of S. bovis in the intestinal tract of healthy racing pigeons was determined. Crop and cloaca swab samples obtained from 810 pigeons from 14 different lofts and from 122 pigeons that were presented for routine health control were examined for the presence of S. bovis. Pooled faecal samples were also obtained from pigeons in 82 different pigeon lofts. S. bovis was isolated from crop or cloaca samples of approximately 40 % of pigeons of all ages by direct culture and from 80 % of the pooled faecal samples by enrichment culture.

In a longitudinal study, crop and cloaca samples were collected every 3 months from pigeons in seven different pigeon lofts. The prevalence of S. bovis in these pigeons ranged from 0 to 100 %. The carriage rate was not related to the season or to the age of the pigeons.

The prevalence of S. bovis in organ lesions of pigeons examined at necropsy was investigated over a 35‐month period. S. bovis was isolated from 10 % of the birds examined. The incidence of S. bovis septicaemia was significantly higher in January to August than in September to December. It was concluded that S. bovis is an opportunistic pathogenic agent in pigeons.     

Prevalence of antimicrobial residues in pork meat in Madagascar

Residual antimicrobials in food constitute a risk to human health, but poor knowledge is available about the significance of contaminated meat in developing countries. The purpose of the study was to determine the occurrence of antimicrobial drug residues in pork products in Madagascar. The occurrence of antimicrobial drug residues in pork meat were investigated by the Premi® test (DSM^©) technique. There was a high incidence rate of drug residues, with 360 (37.2 %) meat samples being contaminated. A significant increase was observed between 2010 and 2011, with 32 and 39%, respectively. Pork meat samples are less contaminated by drug residues when animals are slaughtered in urban abattoirs (34.4%) vs in provincial abattoirs (42.2%), suggesting that animals under treatment (or sick) are sold preferentially in local abattoir. Drug residue levels in pork meats purchased in Madagascar appear to be serious public health problem at the moment.     

Antibiotic residues in milk samples obtained from cows after treatment for papillomatous digital dermatitis.

OBJECTIVE: To determine whether there would be detectable antibiotic residues in milk obtained from dairy cattle with papillomatous digital dermatitis (PDD) after topical treatment with oxytetracycline. DESIGN: Randomized controlled clinical trial. ANIMALS: 28 lactating Holstein cows with PDD. PROCEDURE: Cows were assigned to 2 treatment groups. Treatment 1 (n = 16) consisted of spraying of PDD lesions with 15 ml of a solution containing 100 mg of oxytetracycline/ml; lesions were sprayed twice daily for 7 days, using a garden sprayer. Treatment 2 (n = 12) consisted of a one-time application of a bandage that consisted of cotton soaked with 20 ml of a solution containing 100 mg of oxytetracycline/ml. Milk samples were obtained before and after treatment and assayed for tetracycline content by use of high-performance liquid chromatography and a commercially available tetracycline screening test. RESULTS: None of the cows in either treatment group had violative residues of oxytetracycline in milk samples. CONCLUSIONS AND CLINICAL RELEVANCE: Producers treating lactating cows that have PDD, via topical application of oxytetracycline solution at the concentrations reported in this study, have a low risk of causing violative antibiotic residues in milk.     

Efficacy and Dissipation of Permethrin for the Control of the Northern Fowl Mite in Hens

Laying hens were treated with permethrin at the rate of 20 mg per bird to determine efficacy against northern fowl mites Ornithonyssus sylviarum (Canestrini and Fanzago) and the dissipation of residues over a 42-day period. Permethrin provided greater than 99% control of mites for at least 42 days posttreatment as compared to malathion which did not substantially reduce mite infestations. Carbaryl and coumaphos treatment resulted in limited reductions with mite populations recovering by two to three weeks posttreatment.

Maximum residues of permethrin in breast muscle, body fat and the uropidium occurred on day 1 posttreatment and were still present in fatty tissue in detectable quantities on day 42. Residues in egg yolk appeared on day 3 posttreatment and peaked on day 7 with trace quantities still present on day 21. Permethrin was not found in egg white. Low residues were found in the liver and gizzard from day 1 through to day 7.

     

Reduction of ochratoxin A in broiler serum and tissues by Trichosporon mycotoxinivorans

The present study was planned to evaluate the possible transmission of ochratoxin A (OTA) in serum and targeted organs of broilers fed on two levels (500 and 1000 ppb) this toxin in the presence or absence of a toxin deactivator (containing a mycotoxin deactivating yeast Trichosporon mycotoxinivorans) at two inclusion levels (1 and 2 kg/ton of feed) to 270 day-old broiler chicks divided into nine groups (A-I) over a 42 days period. Serum samples were collected at 14, 28 and 42nd day of experiment, whereas, liver and kidney tissues were obtained from broilers slaughtered at 42nd day of experiment. The highest OTA levels were detected in serum, livers and kidneys of OTA treated groups without supplementation of toxin deactivator (groups D and G) at day 42 of experiment, while the residues were significantly (P<0.01) lower in treatment groups (F and I) supplemented with toxin deactivator at 2 kg/ton of feed. The order of OTA level was serum>kidneys>liver.     

Some observations on the liver copper status of pigs in the northern part of New Zealand

The copper content of the livers from 347 pigs was analysed. Two hundred and three of these samples were from animals varying in age from full term foetus to five years, which were submitted to the laboratory (laboratory cases) for a variety of diagnostic tests. The remaining 144 liver samples were obtained from pigs slaughtered at an abattoir (abattoir survey) at 75-S kg liveweight (approximately 20–30 weeks old).

Liver copper levels of 12 mg/kg D.M. (Dry Matter) or less, a level consistent with copper deficiency, were found in 6.9% of the laboratory cases and in 9.0% of the abattoir survey pigs. Liver levels less than 20 mg/kg suggesting insufficient dietary copper to produce a growth-promoting effect, were found in 21.6% of the former and 36.1% of the latter pigs.

A significantly greater frequency of illthrift and anaemia was found in the laboratory cases in which liver copper levels were less than 20 mg/kg compared with animals with higher levels. Liver copper levels less than 20 mg/kg were also more common in pigs derived from dairy farms or fed garbage than in animals from pig farms or fed on meal.

All of 26 samples of commercial pig meal analysed contained sufficient copper to satisfy the daily essential copper requirements of pigs (greater than 5–6 mg/kg) but 14 of these (53.8%) contained less than 125 mg/kg levels of copper and were unlikely to produce a growth-promoting effect.     

饲粮精氨酸水平对肉仔鸡免疫功能及其抗FAdV-4影响的研究

本试验旨在研究饲粮精氨酸水平对肉仔鸡免疫功能及其抗禽腺病毒I群4型（fowl adenovirus serotype 4,FAdV-4）的影响。选取1日龄罗斯（Ross）308肉仔鸡300只,随机分为5组（每组5个重复,每个重复12只）,设置5个饲粮精氨酸水平组,分别为0.96%、1.20%、1.44%、1.68%和1.92%,试验鸡饲养至21日龄,各重复随机选取4只测定血清免疫指标和免疫相对器官指数。随后各重复再次随机选取6只,并分为感染组和对照组,感染组肌肉注射FAdV-4 NP毒株0.2 mL（TCID₅₀=10^-6.23/0.01 mL）,对照组肌肉注射等量灭菌生理盐水,感染2 d后,统计死亡率、发病率,ELISA测定肝组织iNOS水平、qPCR测定肝iNOS mRNA表达量及病毒载量。结果表明：1）饲粮精氨酸水平为1.44%、1.68%和1.92%时,均能显著提高脾脏指数（P<0.05）且精氨酸水平为1.68%能显著提高胸腺指数（P<0.05）,而精氨酸水平为0.96%会显著降低脾脏、胸腺和法氏囊指数（P<0.05）。2）1.68%精氨酸水平组能显著提高血清球蛋白（GLO）、IgG水平和球蛋白/白蛋白（G/A）比值（P<0.05）;精氨酸水平为0.96%显著降低血清球蛋白和IgG水平（P<0.05）。3）精氨酸水平为0.96%可显著降低肉仔鸡血清中IL-1β、TNF-α、iNOS和NO水平（P<0.05）,而1.68%和1.92%精氨酸水平组均能显著提高肉仔鸡血清中IL-1β、TNF-α、IFN-γ和iNOS水平（P<0.05）。4）肉鸡感染FAdV-4后,0.96%精氨酸水平组的死亡率会显著高于1.20%、1.44%、1.68%和1.92%组（P<0.05）。5）ELISA测定结果显示,1.44%、1.68%和1.92%精氨酸水平组能显著提高感染后的肝组织iNOS水平。6）1.44%、1.68%和1.92%精氨酸水平组均能显著提高肝iNOS mRNA表达水平（P<0.05）;肉鸡感染FAdV-4,iNOS mRNA水平均会显著降低（P<0.05）,1.44%、1.68%和1.92%精氨酸水平组能提高感染FAdV-4后肝iNOS mRNA水平（P<0.05）并显著降低肝的病毒载量（P<0.05）。由此可见,肉仔鸡饲粮中精氨酸的不足会降低其机体的免疫功能及抗FAdV-4病毒能力。提高肉仔鸡饲粮中精氨酸水平不仅能提高免疫器官指数、血清免疫因子水平及肝iNOS mRNA表达水平,降低肝的病毒载量,从而提高机体免疫功能和抗病毒能力。     

Trace element levels in liver and kidney from cattle, swine and poultry slaughtered in Canada.

Levels of arsenic, cadmium, copper, mercury and lead were determined in approximately 650 samples of liver and kidney from cattle, swine and poultry slaughtered in Canada during 1979-81. In addition zinc levels were determined in livers and kidneys from swine, and selenium and zinc levels were determined in the livers and kidneys from cattle. Depending on the element several methods of atomic absorption spectroscopy were used to analyze samples including flame, hydride generation, cold vapour generation and graphite furnace atomization. Analyses were also done by plasma emission spectroscopy. Levels of arsenic over 2.0 micrograms/g were detected in 0.9% of swine livers and 0.3% of swine kidneys. Cadmium levels higher than 1.0 micrograms/g were detected in 0.3% of cattle livers, 10.8% of cattle kidneys, 1.8% of swine kidneys, 0.4% of poultry livers and 0.3% of poultry kidneys. Levels of copper over 150 micrograms/g were detected in 0.4% of cattle and swine livers. Levels of lead over 2.0 micrograms/g were detected in 1.4% of poultry livers and 1.6% of poultry kidneys. The highest level of mercury detected in all species was 0.25 micrograms/g and the highest level of selenium was 1.9 micrograms/g. Zinc levels of over 100 micrograms/g were detected in 1.7% of cattle livers, 0.2% of cattle kidneys and 5.0% of swine livers.     

The Duration of Farrowing in Relation to the Reproductive Performance of Yorkshire Sows

Records for 212 attended farrowings by 38 Yorkshire sows were examined. Eighty per cent of the farrowings were less than six hours, 18 per cent between six and 12 hours and two per cent between 12 and 17 hours duration. There appeared to be no marked relationship between the duration of farrowing and the size of litter.

In spite of a higher stillbirth rate in males, there were more male (52.3 per cent) than female piglets born alive. As the time taken to farrow increased from within 1-3 hours to more than eight hours, the percentage of stillborn piglets and the percentage of litters with stillbirths increased to 10.5 from 2.4 and to 61.1 from 18.2 per cent respectively.

Twenty-nine per cent of the litters were farrowed on the 114th day of gestation. As the gestation period lengthened to 117 days or more, from 113 days or less, there were corresponding increases in the duration of farrowing and the incidence of stillbirths, and a decrease in litter size.

A need to investigate the use of hormones to control parturition in sows was suggested.

     

Effects of a mastitis control programme on the incidence of clinical mastitis

Summary

The results of a mastitis control field experiment in Utrecht over three and a half years, including sevens herds with a total of 225 lactating cows are presented. Every case of clinical mastitis was examined bacteriologically. Quarter samples were taken routinely at an average interval of five weeks.

The incidence of clinical mastitis in each herd at the start of the experiment varied from 10 to 104 quarter cases per 100 cows per year. The majority of cases of clinical mastitis (33.1 per cent) occurred during the first month of lactation.

In 74.4 per cent of the lactations marked by clinical mastitis only a single case was observed during that lactation period. If the animals were on pasture during the first month of lactation, the incidence of clinical mastitis was significantly lower during this month, compared with the first month when they were housed. Str. dysgalactiae was the most common isolate from clinical cases (21.5 per cent). A total proportion of 40.3 per cent of the clinical cases were caused by cocci, 20.3 per cent by Gram‐negative bacteria and 16.0 per cent were bacteriologically negative. Of the clinical cases caused by streptococci and staphylococci, 33.3 per cent were preceded by subclinical infection, compared with 11.8 per cent of the clinical cases due to E. coli. The overall incidence of clinical mastitis in this experiment decreased from 47 to 31 per 100 cows per year.     

气相色谱-质谱法同时测定猪肝中盐酸克伦特罗、莱克多巴胺残留

猪肝用乙酸乙酯、盐酸溶液提取后，经SCX固相萃取柱净化、BSTFA衍生化，定容后用气相色谱-质谱（GC／MS）外标法测定。测定结果表明：采用该方法，猪肝中盐酸克伦特罗和莱克多巴胺的检出限分别为0．3、1．0ng／g。盐酸克伦特罗在3．0～300ng／mL范围内与峰面积具有良好的线性关系，平均回收率为85．6％；莱克多巴胺在10～1000ng／mL范围内与峰面积具有良好的线性关系，平均回收率为76．6％。该方法简便可靠、干扰小、灵敏度高，可用作猪肝中克伦特罗和莱克多巴胺残留的同时测定。     

Subclinical ketosis in post-partum dairy cows fed a predominantly pasture-based diet: defining cut-points for diagnosis using concentrations of beta-hydroxybutyrate in blood and determining prevalence

AIMS: Firstly, to define, in dairy cows in the first 5 weeks post-calving fed a predominantly pasture-based diet, cut-points of concentrations of beta-hydroxybutyrate (BHBA) in blood, above which there were associations with purulent vaginal discharge (PVD), reduced pregnancy rates (PR) and decreased milk production, in order to better define subclinical ketosis (SCK) in such cattle; and secondly, to determine the prevalence, incidence and risk factors for SCK.

METHODS: An observational field study was conducted in 565 cows from 15 spring-calving and predominantly pasture-fed dairy herds in two regions of New Zealand during the 2010– 2011 dairy season. Within each herd, a cohort of randomly selected cows (approximately 40 per herd) was blood sampled to determine concentrations of BHBA on six occasions at weekly intervals starting within 5 days of calving. The key outcome variables were the presence/absence of PVD at 5 weeks post-calving, PR after 6 weeks (6-week PR) and after the completion of the breeding season (final PR), and mean daily milk solids production.

RESULTS: Two cut-points for defining SCK were identified: firstly concentration of BHBA in blood ≥1.2?mmol/L within 5 days post-calving, which was associated with an increased diagnosis of PVD (24 vs. 8%); and secondly concentration of BHBA in blood ≥1.2?mmol/L at any stage within 5 weeks post-calving, which was associated with decreased 6-week PR (78 vs. 85%). The mean herd-level incidence of SCK within 5 weeks post-calving was 68 (min 12; max 100)% and large variations existed between herds in peak prevalence of SCK and the interval post-calving at which such peaks occurred. Cows >8 years of age and cows losing body condition were at increased risk of SCK within 5 weeks of calving.

CONCLUSIONS: Cows with concentration of BHBA in blood ≥1.2?mmol/L in early lactation had a higher risk of PVD and lower 6-week PR. Cow and herd-level prevalence of SCK varied widely in early lactation.

CLINICAL RELEVANCE: Subclinical ketosis is common and is significantly associated with reproductive performance in mainly pasture-fed New Zealand dairy cattle. Controlling SCK may therefore result in improvements in herd reproductive performance. However considerable variation exists among herds in the incidence of SCK and in the timing of peak prevalence which means that herd-specific monitoring programmes are required to define herd SCK status accurately.     

Milk residues and performance of lactating dairy cows administered high doses of monensin

Milk residues and performance were evaluated in lactating cows that were fed up to 10 times the recommended dose of monensin. Following an acclimatization period of 14 d, during which cows were fed a standard lactating cow total mixed ration containing 24 ppm monensin, 18 lactating Holstein dairy cows were grouped according to the level of feed intake and then randomly assigned within each group to 1 of 3 challenge rations delivering 72, 144, and 240 ppm monensin. Outcome measurements included individual cow daily feed intakes, daily milk production, body weights, and monensin residues in composite milk samples from each cow. There were no detectable monensin residues (< 0.005 microg/mL) in any of the milk samples collected. Lactating cows receiving a dose of 72 ppm monensin exhibited up to a 20% reduction in dry matter intake, and a 5% to 15% drop in milk production from the pre-challenge period. Cows receiving doses of 144 and 240 ppm monensin exhibited rapid decreases in feed intake of up to 50% by the 2nd d and milk production losses of up to 20% and 30%, respectively, within 4 d. Lactating cows receiving up to 4865 mg monensin per day had no detectable monensin residues (< 0.005 microg/mL) in any of the milk samples collected. Results of this study confirm that food products derived from lactating dairy cattle receiving monensin at recommended levels are safe for human consumption.     

Ostertagiasis in calves. II. infection parameters and body weight gains following housing

The performance of six groups of six calves each from a previous field experiment was followed from the beginning of housing until turning out seven months later. When housed the groups harboured different levels of infection with Ostertagia ostertagi and had corresponding weight and gain reductions. The most heavily infected groups improved rapidly following housing. Elevated serum pepsinogen levels decreased markedly, and approached normal values at eight weeks. Differences in serum pepsinogen levels between groups diminished considerably, but remained significant over the entire stabling period. The serum albumin level was low in the most seriously affected animals at the time of housing, but normal levels were restored within the first twelve weeks. In general, the number of parasite eggs in the faeces of the animals decreased, but there was considerable fluctuation. Apart from a single sampling date, no significant difference in egg per gram (EPG) could be demonstrated between the experimental groups during the stabling period.The calves were fed according to their age. The live weight differences between most and least affected groups diminished from 64 kg at the time of housing to 37 kg at the end of the stabling period. The reduction took place particularly during the first four weeks of housing.Considering both the grazing and stabling periods, it appeared that anthelmintic treatment twice during the period had no effect on the final live weight, whereas remeated treatments at three-week intervals resulted in an increase of 24 kg. Similarly, moving the animals to a clean pasture in mid-July resulted in an increase of 39 kg at the end of the stabling period when compared to calves which were not moved. Treatment of moved animals did not result in further body weight gain after seven months of housing.No significant correlation was found between parasite EPG of faeces and growth rate during the stabling period. However, a positive correlation was found between serum pepsinogen during the first eight weeks of housing and the weight gain over the entire stabling period. This was in contrast to the correlation experienced during the grazing period.