How milk-fed dairy calves perform in stable versus dynamic groups

The objective of the present field trial was to compare calf performance among pre-weaned calves in two different group housing systems, stable groups (“all in–all out”) and dynamic groups (continuous introduction). Performance data was collected from 484 calves randomly assigned to the two systems at six large (230–450 cows) commercial Danish dairy herds. All six farms had both systems simultaneously in the same stall, and under identical management and feeding regimes.Calves in stable groups had significantly higher daily live weight gain than calves in dynamic groups (870 vs. 810 g/days). The prevalence of both diarrhoea and respiratory disease were more than twice as high among calves in dynamic groups compared to calves in stable groups.     

Detection of calves persistently infected with bovine pestivirus in a sample of dairy calves in south-eastern Queensland

Objective To determine the proportion and incidence of calves persistently infected with bovine pestivirus in calves (n = 1521) supplied to the Tick Fever Research Centre and to assess the test regime to detect calves persistently infected with bovine pestivirus.
Design Calves, 1 to 6 weeks old, selected for use in the production of the tick fever vaccine were collected from 21 properties in 56 separate groups between October 1990 and December 1996. Each group was examined for the presence of calves persistently infected with bovine pestivirus.
Procedure All calves were routinely tested for antibody to bovine pestivirus and bovine pestivirus antigen using a serum neutralisation test and an antigen-capture ELISA, respectively. Pooled lymphocyte samples from calves were also monitored for bovine pestivirus by inoculation of sheep. Whole herd testing was carried out in eight herds, using a serum neutralisation test as a screen test followed by an antigen-capture ELISA of cattle with a serum neutralisation test titre of less than 32.
Results Fourteen of the 1521 calves tested (0.9%), were detected as persistently infected and the incidence ranged from 0.0 to 3.0 % per year over 6 years. Persistently infected calves were found in 13 of the 59 groups and originated from 7 of the 21 herds used. In whole herd testing on the properties of origin, cattle persistently infected with bovine pestivirus were detected in four of the eight herds tested
Conclusions The proportion of calves persistently infected with bovine pestivirus is similar to that in other countries and indicates that bovine pestivirus could be a significant cause of economic loss in Australian cattle herds. In detecting calves persistently infected with bovine pestivirus, the combination of sheep inoculation, paired antigen-capture ELISA and serum neutralisation tests appeared to be highly sensitive and specific.     

Mycoplasma bovis and otitis in dairy calves in the United Kingdom

Signs of severe otitis media in 20% of dairy calves on one farm were associated with Mycoplasma bovis infection, based on isolation from the external ear canal and nares. Affected calves seroconverted to M. bovis and no other significant bacteria were isolated. Infection was considered likely to have originated from cows in the milking herd based on evidence of seroconversion and detection of infection in a milk sample. M. bovis infection should be considered when investigating otitis problems in calves.     

Prevalence of respiratory bacterial pathogens and associated management factors in dairy calves in Taiwan

This study aimed to investigate the prevalence at both farm-level and calf-level and to identify the risk factors of respiratory bacterial pathogens in dairy calves in Taiwan. The status of bovine respiratory disease (BRD) was evaluated by using the Wisconsin scoring system from a total of 400 pre-weaned calves from 32 different farms in Taiwan, then the nasopharyngeal swabs were collected. The prevalence of respiratory pathogens was 84.37% at farm-level and 45.50% at calf-level, and Pasteurella multocida (P. multocida) was the most prevalent pathogen. The presence of Mycoplasma bovis (M. bovis), P. multocida, Mannheimia haemolytica (M. haemolytica) and Histophilus somni (H. somni) were all higher in BRD positive calves than BRD negative calves, but only in H. somni was significant (P<0.001). Then nine farm management risk factors were analyzed by using multivariate logistic regression models to determine the risk factors of respiratory bacterial pathogens (farm and calf-level). In the result at farm-level, only unheated colostrum was significantly associated with pathogen positive farms (Odds Ratio (OR)=11.43). At calf-level, the predominant risk factor for each pathogen, M. bovis, P. multocida, M. haemolytica and H. somni, was late first colostrum feeding (OR=272.82), unheated colostrum (OR=3.41), waste milk feeding (OR=6.59) and high pneumonia treatment cost (OR=2.52), respectively. For effective preventive measures, farmer education on milk and colostrum feeding are urgently warranted.     

Hematology and serum biochemistry of Holstein dairy calves: age related changes and comparison with blood composition in adults

Specific reference intervals are needed for each animal species for appropriate interpretation of hematological and serum biochemical results. The aim of the present study was to investigate the blood composition of growing calves in order to evaluate the need for defining reference values for different age groups. Thirty two Holstein calves (18 male and 14 female) were blood sampled. A blood sample was taken within 24-48 h following birth and at 14, 28, 42, 56, 70 and 84 days of age. CBC determination and the measurements of some blood serum metabolites, enzymes, electrolytes and minerals were performed. There were significant age related changes for most hematological and biochemical parameters (p < 0.05) except for the numbers of band neutrophils and monocytes and the amounts of sodium, potassium, chloride and BUN. The results of the present study showed that for some hematological and biochemical parameters such as hemoglobin, MCV, MCH, MCHC, inorganic phosphorus, serum total protein, globulin, AST and ALP at the first three months of life and also, neutrophil numbers and glucose levels at the 24-48 h of life, the age specific reference values must be considered for precise interpretation of laboratory results.     

Prevalence of bovine group A rotavirus shedding among dairy calves in Ohio.

Fecal samples were collected from 450 neonatal calves, ranging from 1 to 30 days old, between May, 1988 and May, 1989 to estimate the prevalence of bovine group A rotavirus in a stratified random sample of Ohio dairy herds. Calves were from 47 dairy herds chosen to be representative of Ohio herds. Bovine group A rotavirus was detected in fecal samples by a cell culture immunofluorescence test (CCIF) and ELISA. Of 450 samples tested, 46 (10%) were positive by CCIF and 67 (15%) were positive by ELISA. The agreement beyond chance between the 2 assays was good (kappa = 0.65). The overall prevalence rate of rotavirus shedding was 16.4% (74/450). Forty-three percent (29/67) of the samples positive by ELISA were subgroup 1, none were subgroup 2, and the remaining 57% (38/67) could not be assigned to either subgroups 1 or 2. Thirty herds (62.5%) had at least 1 group A rotavirus-positive calf (mean number of samples per positive herd = 12.4), and 17 herds (37.5%) had no rotavirus-positive calves (mean number of samples per negative herd = 6.0). A live oral rotacoronavirus vaccine was used in neonatal calves of only 1 herd and 3 of 17 (17.6%) calves from this herd were positive for group A rotavirus. The percentage of the rotavirus-positive fecal samples from all calves (n = 450) when stratified by fecal consistency was as follows: 28.3% (13/46) had liquid feces; 25.6% (10/39) had semiliquid feces; 23.4% (22/94) had pasty feces; and 10.7% (29/271) had firm feces.(ABSTRACT TRUNCATED AT 250 WORDS)     

Longitudinal study of bovine rotavirus group A in newborn calves from vaccinated and unvaccinated dairy herds

Reports of rotavirus excretion in calves usually result from cross-sectional studies, and in face of the conflicting results regarding protection of calves born to vaccinated dams against diarrhea, the aim of the present study was to evaluate rotavirus excretion in dairy calves born to vaccinated or unvaccinated dams, to identify the genotypes of bovine rotavirus group A (RVA) strains isolated from these animals as well as to investigate characteristics of the disease in naturally occurring circumstances throughout the first month of life. Five hundred fifty-two fecal samples were taken from 56 calves, 28 from each farm and, in the vaccinated herd, 11/281 samples (3.91%) taken from six different calves tested positive for RVA while in the unvaccinated herd, 3/271 samples (1.11%) taken from 3 different calves tested positive. The genotyping of the VP7 genes showed 91.2% nucleotide sequence identity to G6 genotype (NCDV strain), and for the VP4 gene, strains from the vaccinated herd were 96.6% related to B223 strain, while strains from the unvaccinated herd were 88% related to P[5] genotype (UK strain). Genotypes found in this study were G6P[11] in the vaccinated herd and G6P[5] in the unvaccinated herd. All calves infected with rotavirus presented an episode of diarrhea in the first month of life, and the discrepancy between the genotypes found in the commercial vaccine (G6P[1] and G10P[11]) and the rotavirus strains circulating in both vaccinated and unvaccinated herds show the importance of keeping constant surveillance in order to avoid potential causes of vaccination failure.     

Factors associated with morbidity,mortality, and growth of dairy heifer calves up to 3 months of age

Calfhood disease is an important problem on many dairy operations that can have substantial effects on heifer survival and productivity, and has economic and welfare impacts. Neonatal calf diarrhea (NCD) and bovine respiratory disease (BRD) are the most common causes of morbidity and mortality in young dairy cattle. The objective of this observational study was to investigate factors associated with the risks of morbidity and mortality, and with growth, in commercial dairy heifers calves. A total of 2874 heifer calves from 19 commercial dairy farms in Minnesota and Ontario were enrolled at 1–7 days of age and followed for approximately 3 months. Using cut-points of serum total protein of 5.2 and 5.7 g/dl, the incidences of failure of transfer of passive immunity (FTPI) were 11 and 32%, respectively. A cut-point of 5.7 g/dl was the most predictive of BRD before 5 weeks of age (sensitivity = 40%, specificity = 69%). The positive predictive value was poor (PPV = 18%), but the negative predictive value was good (NPV = 87%). A cut-point of 5.2 g/dl was most predictive of death before 5 weeks of age (sensitivity = 27%, specificity = 89%, PPV = 5%, NPV = 98%). Serum total protein during the first week of life was a poor predictor of NCD. Over 23% of calves were treated for diarrhea. Risk factors were weight at enrollment, other diseases before 2 weeks of age, and an interaction between season of birth and herd-level incidence of NCD. Almost 22% of calves were treated at least once for BRD. Factors associated with an increased risk of BRD included herd-level incidence of BRD, season of birth, navel dipping, other diseases before 2 weeks of age, failure of transfer of passive immunity, and manual control of temperature in pre-weaning housing. Administration of supplemental antibody products at birth was associated with a reduced incidence of BRD. Overall mortality was 3.5%. Risk of mortality was increased by treatment for BRD and other diseases. The mean average weight gain was 0.95 kg/day (range: 0.11–1.62 kg/day; SD = 0.2). Twinning status, FTP, treatment for NCD or other diseases, and month of birth influenced body weight. This study illustrated relationships among various diseases, mortality, and growth. Furthermore, it demonstrated the importance of colostrum for protection against BRD and improved growth performance, while bringing into question the optimal method of determining failure of transfer of passive immunity.     

Longitudinal identification of Enterocytozoon bieneusi in dairy calves on a farm in Southern Xinjiang,China

Enterocytozoon bieneusi is the most common species responsible for human and animals microsporidiasis. A total of 250 samples were collected weekly from 25 newborn dairy calves of a farm in Southern Xinjiang, China at one to ten weeks of age. Enterocytozoon bieneusi was identified and genotyped by nested PCR amplification and sequencing of internal transcribed spacer (ITS) region.The cumulative prevalence of E. bieneusi infection was 100% (25/25), and the average infection was 52.0% (130/250). The highest infection rate was recorded at six weeks of age (92.0%, 23/25), and no infection was observed at one and two weeks of age. Sequencing analysis showed nine E. bieneusi genotypes (J, EbpC, PigEBITS5, CHV4, CHC3, CS-9, KIN-1, CH5, and CAM5) were identified. The highest genetic polymorphism was observed at ten weeks of age. Genotype J was the predominant E. bieneusi genotype. Phylogenetic analysis clustered genotype J into Group 2 and other eight genotypes (EbpC, PigEBITS5, CHV4, CHC3, CS-9, KIN-1, CH5, and CAM5), detected in 22 (16.9%, 22/130) samples, into Group 1. Among the genotypes, EbpC, KIN-1, and J have been identified in humans. The highest E. bieneusi infection rate (57.9%, 124/214) was observed in fecal samples with formed feces with no diarrhea (p < 0.01), and high genetic polymorphism was observed in class I fecal samples. The presence of zoonotic E. bieneusi genotypes in dairy calves suggests the possibility of transmitting zoonotic infections to humans. It provides the basic data on dynamic change of E. bieneusi in calves.     

Fecal excretion of alcohols and organic anions in neonatal dairy calves

To clarify colonic fermentation during the perinatal period, 22 dairy calves less than 6 weeks old were used. They were given a milk replacer following colostrum feeding. A total 100 samples of normal feces including meconium were collected from the rectum of the calves. Fecal pH, alcohols, lactate and volatile fatty acids (VFAs) were analyzed. Higher ethanol and n -propanol concentrations were found in many fecal samples particularly in the first 2 weeks after birth, but these metabolites showed consistently lower concentrations thereafter. By contrast, higher concentrations of methanol were observed in some samples for all ages examined. Fecal VFA increased abruptly within a few days of birth, and mainly consisted of acetate and n -butyrate. During the first 2 weeks, the proportion of n -butyrate in VFAs decreased and that of propionate increased gradually. Proportions of VFAs were almost stable at 3–6 weeks of age (acetate, propionate and n -butyrate in increasing order). Higher concentrations of lactate and lower pHs were observed in the fecal samples during the first 2 weeks, and concentrations decreased thereafter. Accelerated colonic production of ethanol and n -propanol was confirmed during the early 2 weeks, in addition to organic acid fermentation as reported previously.     

Detection and analysis of bovine rotavirus strains circulating in Australian calves during 2004 and 2005

Bovine rotavirus (BRV) has been detected in both dairy and beef cattle herds worldwide. Stool samples collected from calves in the Gippsland region of Victoria, Australia were screened to determine the presence of BRV. A total of 100 faecal samples were collected from calves with and without diarrhoea across three farms during 2004 and 2005. Group A BRV was detected in 26% of faecal samples (22 from diarrheic calves and four from asymptomatic calves). Genotyping analysis of rotavirus positive samples indicated that G6P[5] was the most prevalent genotype (38.5%) followed by G6P[5 + 11] (15.4%). G10P[11] and G6 + G10P[5] were each detected at a rate of 7.7%, and G6 + G10P[11] was found in a single sample (3.8%). Seven samples (26.9%) could not be G and/or P typed. Thirty percent of the BRV positive samples were mixed infections, indicating that individual calves were co-infected with more than one strain of rotavirus. The G6P[5] strains exhibited high VP7 identity (>97% amino acid identity) with B-60, a G6 strain identified in Victorian calves during 1988. A G10P[11] isolate was closely related (>97% amino acid identity in VP7 and VP4 proteins) to a Victorian G10P[11] strain (B-11) also identified during 1988. This study demonstrates that BRV is a contributing pathogen to diarrhoeal disease in Victorian calves, with sequence analysis suggesting long-term conservation of the VP7 protein over a 16-year period.     

Effects of supplementation level and particle size of alfalfa hay on growth characteristics and rumen development in dairy calves

The aim of this study was to assess the effects of particle size (PS) of alfalfa hay on growth characteristics and rumen development in dairy calves at two levels of alfalfa supplementation. Fifty newborn dairy calves (42.7 ± 2.2 kg BW) were used in a 2 × 2 factorial arrangement with the factors supplementation level (low, 8%; or high, 16% on DM basis) and PS (medium, 2.92 mm; or long, 5.04 mm as geometrical means) of alfalfa hay. In addition, a control group without alfalfa hay was used. Hence, treatments were: control (C); low level with medium PS (LM); low level with long PS (LL); high level with medium PS (HM) or high level with long PS (HL). Growth performance of alfalfa‐fed calves did not differ from control calves, but alfalfa supplementation decreased corneum thickness of the rumen wall. In alfalfa‐fed calves, post‐weaning starter intake was greater for LL calves than for LM calves. During the entire rearing period, starter intake was 26–32% higher for LL and HM calves than for LM calves. Pre‐weaning average daily gain was higher for LL and HM calves than for HL calves, but this effect was not persistent over the entire rearing period. Final body weight decreased from 86 to 79 kg when the level of long PS alfalfa hay increased from 8 to 16%, but increased from 78 to 87 kg when the level of medium PS alfalfa increased from 8 to 16%. Regardless of PS and level, morphometric characteristics of rumen wall were generally similar among alfalfa feeding groups, but corneum thickness decreased from 8.7 to 6.1 μm with greater PS at the low level. These results indicate that adequate, but not excessive, physical stimulation is required for appropriate rumen development and growth performance of dairy calves.     

Approachability and contact behavior of commercial dairy calves to humans

Calves (n = 106) on four dairy farms were observed for their approachability to humans. All calves experienced similar rearing conditions: Beginning individual pen, after birth until weaning at about 2 months, where they were housed individually and fed milk and a milk replacement; Late individual pen, after weaning until grouping at about 3.5 months, where they were housed individually and fed hay, silage and concentrate feed; Beginning group pen, after grouping until 5 months, where they were housed in groups of 2–5 animals and fed hay, silage and concentrate feed; later group pen, from 5 to 7 months. The number of calves that contacted an experimenter who stood in front of their pens for 10 min was recorded on 6 separate days over 3 months. Latency to touch and time spent in activities during touching such as sucking, licking, biting and rubbing were also measured. There were no significant differences in the latency to touch and the ratio of touch to non‐touch calves between the rearing conditions and the farms. The time spent touching was significantly affected by the interaction between the rearing condition and the farm (P < 0.01). In detail, the time spent sucking (P < 0.001) and licking (P < 0.01) was different between the rearing condition × farm variables. The proportion of calves that approached and touched the experimenter tended to be higher in the farms in which a stockperson worked longer inside and outside their pens (both ρ = 0.95, P = 0.051). These results were interpreted according to the perspectives of early positive reinforcement with food and the habituation process to humans existing nearby.     

Effects of replacing steam-flaked corn with shredded sugar beet pulp on feed sorting,behavior, blood metabolites,and growth performance of dairy calves

This experiment was conducted to investigate the effects of partial replacement of steam-flaked corn (SFC) with shredded sugar beet pulp (SBP) in the starter diet on selective intake (sorting), feeding and chewing behavior, blood biochemical parameters, and growth in newborn female Holstein dairy calves. A total of 48 calves (3 d old; 40.1 ± 0.84 kg body weight; mean ± SE) were randomly assigned to 1 of 2 feeding treatments containing 0 or 25% SBP (percentage of dry matter [DM]) in the starter diet. Calves were weaned on d 61 and remained in the study until d 81. Intake of starter feed and total intake of DM (milk DM + starter feed DM), crude protein, and neutral detergent fiber were increased (P < 0.05) by feeding SBP; however, intake of starch (P < 0.01) and total intake of ether extract (P = 0.03) were decreased with no apparent effect on total intake of ME. Average daily gain, feed efficiency, final weight, and skeletal growth also showed no significant changes. Circulating concentrations of glucose, total protein, and albumin were not affected by partial replacement of SBP with SFC; however, higher concentrations of blood urea-N (P = 0.01) and a lower albumin-to-globulin ratio (P = 0.03) were observed in SBP- vs. SFC-fed calves. Calves fed SBP sorted more for particles retained on the 4.75-mm sieve (P = 0.02) and against particles retained on the 0.6-mm sieve and bottom pan (P < 0.01). Intake of neutral detergent fibers and starch from particles retained on all sieve fractions was increased and decreased (P < 0.01), respectively, by replacing SFC with SBP. Replacement of SBP with SFC was associated with increased meal length and meal size and increased rumination frequency and length, but decreased intervals between rumination (P ≤ 0.01). Calves fed SBP spent more time eating, rumination, and standing and less time lying and non-nutritive oral behaviors (P < 0.01). In general, 25% replacement of SFC with SBP did not affect calf performance but increased time spent rumination and eating and decreased non-nutritive oral behaviors.     

Herd-level risk factors for infectious diseases in Swedish dairy calves aged 0-90 days

The effect of environmental factors and management routines on the risk of diarrhoea, respiratory disease and other infectious diseases was investigated in 3081 heifer calves 0–90 days old in 122 Swedish dairy herds. The farmers kept records on cases of diseases in their heifer calves and in addition, project veterinarians clinically examined all calves every 2–3 months. At each visit, the veterinarians also measured the ammonia concentration and relative air humidity in the housing facilities for the calves. The cleanliness of the animals and their environment was recorded as a measure of the hygienic status of the farm. The presence or absence of draught (i.e. wind velocity > 0.5 m/s) was recorded twice during the study period. The effect of these factors, as well as the placing of the calf pens, the nature of the pen walls, air volume per animal, management factors (such as the status of the caretaker and feeding routines) and presence or absence of a bovine viral diarrhoea virus (BVDV) infection in the herd, was evaluated by means of a two-level variance component logistic model. The placing of calf pens along an outer wall was significantly associated with the risk of diarrhoea (odds ratio (OR): 1.92, P < 0.01). The risk for respiratory disease was significantly associated with an ammonia concentration below 6 ppm (OR: 0.42, P < 0.05) while the odds ratio for moderately to severely increased respiratory sounds was significantly associated with a BVDV infection in the herd (OR: 2.39, P < 0.05) and draught (OR: 3.7, P < 0.02). Absence of draught was significantly associated with the risk for infectious diseases other than diarrhoea and respiratory disease (OR: 0.42, P < 0.01).     

A case-control study of Washington dairy herds experiencing drug residue violations in market calves

The purpose of this case-control study was to examine the association between management practices and the occurrence of violative drug residues in calves originating from Washington dairies. In 1992, 74 dairies were identified as first-time offenders sending to abattoirs calves less than 1 week of age that had violative residue levels. Of these, 56 answered a subset of previously validated management questions from the 1991–1992 US National Animal Health Monitoring System National Dairy Heifer Evaluation Program (NDHEP) study during a violation investigation and comprised the case group. The controls were the 51 randomly selected Washington dairies that participated in the NDHEP, completed the four NDHEP questionnaires, and had not been identified as having residue violations. Management factors investigated were those associated with maternity and pre-weaning hygiene, vaccination and preventive practices, type and management of liquid calf feed, and general management. Other factors included herd somatic cell count (SCC), the presence of clinical signs associated with diseases of body systems, and herd size. Significant associations were detected between violation occurrence and the management of calving cows, colostrum volume and management, and the person responsible for calf care. Significant associations but of the wrong direction were found between violation occurrence and type and management of liquid calf feed. No significant associations were detected between violation occurrence and the remaining management factors, herd size, animals entering the herd, or SCC.     

河南省部分地区乳牛隐孢子虫病的流行病学调查

为进一步掌握乳牛隐孢子虫病在河南省的流行动态,从河南省郑州、开封、济源和鹤壁4个地区9个奶牛场采集12月龄以内的乳牛粪便样品582份,用饱和蔗糖溶液漂浮法和改良抗酸染色法进行检测。结果显示,隐孢子虫总感染率为26．12％（152／582）。其中,断乳前犊牛（5日龄至2月龄）隐孢子虫感染率为30．91％（51／165）,断乳后犊牛（3～12月龄）感染率为24．22％（101／417）。依据形态数值初步鉴定为2种隐孢子虫,即微小隐孢子虫和安氏隐孢子虫。微小隐孢子虫在断乳前犊牛阳性样品中的比率为50．98％（26／51）,在断乳后乳牛阳性样品中的比率为9．90％（10／101）。另外,饲养方式（断乳前犊牛单独隔离饲养和未隔离饲养）对断乳前犊牛2种隐孢子虫的感染率有显著影响。