Five field trials on the efficacy of a bovine respiratory syncytial virus vaccine

Five field trials evaluated whether immunization of beef cattle prior to weaning, at weaning, or immediately upon arrival at the feedlot with a commercial bovine respiratory syncytial virus (BRSV) vaccine would reduce subsequent treatment for respiratory disease.

Bovine respiratory syncytial virus vaccination was associated with a significant (p<0.05) reduction in treatment rate in one of three groups of calves immunized prior to weaning (−12%) and in calves immunized upon arrival at the feedlot (−4%).

There was no significant (p>0.05) effect of the BRSV vaccine on treatment rate in calves immunized at weaning, in calves immunized upon arrival at the Saskatoon bull test station, or in yearlings immunized upon arrival at the feedlot.

Although the trend in these field trials was to a sparing effect of the BRSV vaccine, the small reduction in treatment rate may not justify the cost of the vaccination program.

     

The lesions of toe tip necrosis in southern Alberta feedlot cattle provide insight into the pathogenesis of the disease

Gross and histologic postmortem studies were performed on the hind feet of feedlot cattle that had, or were free from, lesions of toe tip necrosis. The hind feet of feedlot cattle were collected by 3 veterinary feedlot practices in southern Alberta, Canada. Three studies of these feet were conducted: i) prediction of disease based on the presence or absence of apical white line separation, ii) gross assessment of the distribution and severity of lesions within affected claws, and iii) microscopic evaluation of the distal phalanx and surrounding soft tissues of affected claws. Prediction of toe tip necrosis based on the presence of apical white line separation was statistically significant (P < 0.0001). This, combined with a pattern of lesions indicative of an ascending infection of the distal phalanx and the absence of other lesions, suggests that the pathogenesis involves bacterial infection originating from the most distal aspect of the toe, at the apical white line.     

Relationship of foot conformation and force applied to the navicular bone of sound horses at the trot

REASONS FOR PERFORMING STUDY: Collapsed heels conformation has been implicated as causing radical biomechanical alterations, predisposing horses to navicular disease. However, the correlation between hoof conformation and the forces exerted on the navicular bone has not been documented. HYPOTHESIS: The angle of the distal phalanx in relation to the ground is correlated to the degree of heel collapse and foot conformation is correlated to the compressive force exerted by the deep digital flexor tendon on the navicular bone. METHODS: Thirty-one shod Irish Draught-cross type horses in routine work and farriery care were trotted over a forceplate, with 3-dimensional (3D) motion analysis system. A lateromedial radiograph of the right fore foot was obtained for each horse, and various measurements taken. Correlation coefficients were determined between hoof conformation measurements and between each of these and the force parameters at the beginning (15%) of stance phase, the middle of stance (50%) and at the beginning of breakover (86% of stance phase). Significance was defined as P<0.05. RESULTS: The force exerted on the navicular bone was negatively correlated (P<0.05) to the angle of the distal phalanx to the ground and to the ratio between heel and toe height. This was attributed to a smaller extending moment at the distal interphalangeal joint. There was not a significant correlation between the angle of the distal phalanx and the degree of heel collapse, and heel collapse was not significantly correlated to any of the force parameters. CONCLUSIONS: Hoof conformation has a marked correlation to the forces applied to the equine foot. Heel collapse, as defined by the change in heel angle in relation to toe angle, appears to be an inaccurate parameter. The forces applied on the foot are well correlated to the changes in the ratio of heel to toe heights and the angles of the distal phalanx. POTENTIAL RELEVANCE: Assessment of hoof conformation should be judged based on these parameters, as they may have clinical significance, whereas parallelism of the heel and toe is of less importance.     

Efficacy of parenteral antibiotics for disease prophylaxis in feedlot calves

Trimethoprim-sulfadoxine (TMPSDX) and two formulations of oxytetracycline (OTC) were examined for their prophylactic efficacy in feedlot calves when given by intramuscular injection on arrival at a large commercial feedlot. The study included 2,112 high-risk feeder calves that developed disease early in the feeding period. Both formulations of OTC reduced bovine respiratory disease morbidity during the first two weeks on feed and for the entire feeding period by 15-19% (p<0.05), and they also reduced all fatal fibrinous pneumonia by 67% and 84% (p<0.05). All three drugs significantly reduced all fatal disease in animals first treated during the second week on feed, but not for the overall feeding period. Oxytetracycline with 2-pyrrolidone reduced the incidence of all fatal disease by 44% (p<0.05) during the entire feeding period. The case fatality risk for calves first treated during the second week on feed was lower (p<0.05) in the TMPSDX group and in the OTC with polyvinyl-pyrrolidone group.     

The effect of age at weaning on the health status of bull calves in a feedlot

Incidence of morbidity and mortality in a feedlot were compared among 381 bull calves weaned one month apart (October 3 and November 1). The calves were 156 and 192 days old at weaning in the earlier and later weaned groups, respectively. Following an adjustment period, the calves were fed a mixed finishing diet containing 90% concentrate ad lib for 140 days in a feedlot. The rate of morbidity did not differ significantly between the two weaning groups. Sick calves in the earlier weaned group had a longer treatment period than those in the later weaned group (3.2 vs 1.4 days, p<0.05). Infections of the respiratory tract were the major cause of sickness and most of the respiratory infections occurred in the early stages of the feedlot period. The frequency of respiratory infections was higher among the earlier weaned calves compared with that in the later weaned group (p<0.01) indicating a higher susceptibility to these infections when calves were weaned at younger ages. Bloat was the second most common health problem among the bulls; however, its incidence did not differ between the two groups (p>0.05). The rate of mortality did not differ significantly between the two groups.     

Risk factors related to the prevalence of infectious bovine keratoconjunctivitis

A cross-sectional epizootiologic study was conducted by mailed questionnaire to determine how the prevalence of infectious bovine keratoconjunctivitis (IBK) related to selected predisposing causes. The prevalence of IBK in Missouri during the summer of 1978 was 4.97 cases/100 cattle, with 45% of respondents reporting cases of IBK. A higher prevalence of IBK was associated with calves and yearlings, Hereford and Hereford-cross cattle, backgrounding cattle operations, and herds with a history of IBK. Vaccination of mature cattle against infectious bovine rhinotracheitis was associated with significantly higher prevalence of IBK in calves. A significantly lower prevalence of IBK was associated with dairy cattle operations, older cattle, and the winter months. There was no association between the prevalence of IBK and locale, nutrient supplementation, pasture management, use of vaccines other than infectious bovine rhinotracheitis, parasite prophylactic measures, or fly control measures.     

Studies of Enteric Pathogens and γ-Globulin Levels of Neonatal Calves in Sweden

Viring, S., S.-O. Olsson, S. Alenius, U. Emanuelsson, S.-O. Jacobsson, B. Larsson, N. Linde and A. Uggla: Studies of enteric pathogens and γ-globulin levels of neonatal calves in Sweden. Acta vet. scand. 1993, 34, 271-279.– Faecal and blood samples were taken from 10-30% of calves, 36 hours to 14 days old, in 47 dairy herds in different regions of Sweden from September 1987 to October 1988 (Olsson et al 1993). Faecal samples from 279 calves were analysed for the presence of Escherichia coli (K99⁺), rotavirus and Cryptosporidium sp. Twenty (7.2%) of these samples were from diarrhoeic calves. An ELISA was developed and used for the rotavirus analysis. E. coli K99⁺ was detected in 11.5%, Cryptosporidium sp. in 6.1% and rotavirus in 5.4% of the faecal samples. The presence of rotavirus alone and the combination rotavirus and E. coli (K99⁺) was found to be associated with diarrhoea (p<0.001 and p<0.01 respectively).Blood samples from 327 calves were analysed for the level of total protein and γ-globulin. In 43 of these samples (13%) γ-globulin did not separate from the ß₂-region by electrophoresis. The mean total protein concentration was 53.6 g/1 in calves free from diarrhoea. The mean γ-globulin concentration, adjusted to 7 days age was 5.9 g/1. The 20 diarrhoeic calves had lower levels of both total protein and γ-globulin, compared with calves without diarrhoea, but the difference was not significant. One litre more of colostrum at the first feed increased the level of total protein of the calves’ sera by 1.4 g/1 (p = 0.05). Calves born between May and September had a 2.0 g/1 higher (p<0.001) serum concentration of γ-globulin than calves born between October and April.     

An evaluation of antimicrobial therapy for undifferentiated bovine respiratory disease

A field trial of antimicrobial therapy for cases of undifferentiated bovine respiratory disease (UBRD) in beef calves was conducted at four Ontario feedlots. The primary purpose of the trial was to evaluate the efficacy of three different antimicrobials (oxytetracycline, penicillin, and trimethoprim-sulfadoxine) in the treatment of UBRD occurring within the first 28 days postarrival.

The response, relapse, and case fatality rates overall were 85.7%, 14.8%, and 1.4%, respectively, and were not significantly different among the three antimicrobials evaluated. Weight gains of calves treated with the different drugs were not statistically different over the feeding period. Calves that suffered a relapse posttreatment were first treated significantly earlier (p<0.001) in the postarrival period than those that did not relapse. Considered together, treated calves gained significantly less (p<0.05) over the first 28 days and throughout the entire feeding period than controls that were never sick. Cases of UBRD that responded to therapy and did not relapse had rates of gain that were not significantly different from the controls.

     

Incidence of Dystocia and Perinatal Calf Mortality Resulting from Reciprocal Crossing of Double-muscled and Normal Cattle

In order to study the incidence and causes of dystocia and perinatal calf mortality in double-muscled cattle, straight and reciprocal matings between double-muscled and normal cattle were made in three breeding seasons. A total of 348 matings resulted in 247 calvings in the four mating types. The frequency of normal calvings or calvings requiring slight assistance was higher among normal cows mated to double-muscled or normal bulls compared with that of double-muscled cows mated to double-muscled bulls (94% vs 78%, P < 0.05). In general the incidence of dystocia was higher among the double-muscled than the normal cows (19% vs 6%, P < 0.05). Calf birth weight, dam weight at calving, and condition score were not shown to contribute significantly to the differences in the frequencies of dystocia. A higher incidence of dystocia was found in the mating type which frequently gave rise to phenotypically muscular calves (DM × DM). The height, width, and area of pelvic opening were significantly smaller (P < 0.05) in the double-muscled than in the normal cows, indicating that the higher incidence of dystocia and perinatal mortality in double-muscled cattle can be attributed, at least partially, to the smaller area of pelvic opening in the double-muscled cattle.     

Effect of age at feedlot entry on performance and carcass characteristics of bulls and steers

Seventy Angus x Simmental calves (BW = 166.3 +/- 4.2 kg) were used in a 3 x 2 factorial arrangement to determine the effect of age at feedlot entry and castration on growth, performance, and carcass characteristics. At 82 d of age, steers were castrated. Calves were placed in the feedlot at 111 (early-weaned), 202, or 371 (yearling) d of age. Steers were implanted with Synovex-S followed 93 d later with Revalor-S. Calves were harvested on an individual basis when fat thickness was estimated to be 1.27 cm. During the feedlot phase, yearlings gained faster (P < 0.01) than calves placed in the feedlot at 202 or 111 d of age (1.88, 1.68, and 1.62 kg/d, respectively); however, from 111 d of age until harvest, ADG was greatest for early-weaned calves, intermediate for cattle placed in the feedlot at 202 d of age, and lowest for yearlings (1.62, 1.47, and 1.21 kg/d, respectively; P < 0.01). Early-weaned calves spent the most days in the feedlot, followed by calves placed in the feedlot at 202 d of age; yearlings spent the fewest days in the feedlot (221, 190, and 163 d, respectively; P < 0.01). Total DMI when in the feedlot was similar (P = 0.22) among age groups; however, daily DMI was lowest for early-weaned calves, intermediate for calves placed in the feedlot at 202 d of age, and the highest for yearlings (7.1, 8.1, 10.5 kg/ d, respectively; P < 0.01). Early-weaned calves were the most efficient, followed by calves placed in the feedlot at 202 d of age; yearlings were the least efficient (227, 207, 180 g gain/kg feed, respectively; P < 0.01). Weight at harvest (682, 582, 517 kg, respectively; P < 0.01) and hot carcass weight (413, 358, 314 kg, respectively; P < 0.01) were greatest for yearlings, intermediate for cattle placed in the feedlot at 202 d of age, and lowest for early-weaned calves. Early-weaned calves had the smallest longissimus area, followed by calves placed in the feed-lot at 202 d of age; yearlings had the largest longissimus area (77, 86, 88 cm2, respectively; P < 0.01). Calves placed in the feedlot at 111 and 202 d of age had lower yield grades (3.2, 3.1, 3.5, respectively; P < 0.04), and produced fewer select carcasses than yearlings (25, 13, 48%, respectively; P < 0.01). Bulls and implanted steers both had an ADG of 1.7 kg/d when in the feedlot; however, bulls had a greater (P < 0.09) hot carcass weight (370 vs 354 kg) and a larger (P < 0.01) longissimus area (85.8 vs 81.3 cm2) than steers. Earlier feedlot placement resulted in greater quality grades but lower carcass weights.     

Canine Leishmaniasis: Parasitological Follow-up of the Treated Subject

A cross-sectional study was carried out to determine the prevalence of gastrointestinal (GI) nematodes and flukes (Fasciola and amphistomes) infection in communally grazed traditional cattle, zero-grazed small-scale dairy cattle and intensively grazed large-scale dairy cattle through examination of helminth eggs in faeces. Results indicated that the type of management, especially the grazing habit, has a significant influence on the prevalence and intensity of GI nematodes and flukes. The prevalence of GI nematodes in traditional, large-scale dairy and small-scale dairy cattle was 67%, 44.4% and 37%, respectively, with the highest faecal egg counts in calves. The overall prevalence of Fasciola gigantica in traditional, large-scale dairy and small-scale dairy cattle was 63.8%, 46.2% and 28.4%, respectively. The prevalence of amphistomes was 81.9%, 55.5% and 41.1% in traditional, large-scale dairy and small-scale dairy cattle, respectively. The high prevalence of flukes in the traditional system was attributed to communal grazing and watering management practices. Stomach flukes recovered in examined cattle at the abattoir were Calicophoron microbothrium and Cotylophoron jacksoni. About 42.1% of infected animals had both Fasciola and amphistomes. The prevalence of both GI nematodes and flukes varied greatly among villages and farms. The prevalence of both Fasciola and amphistomes was higher in adults (58.5%, 75.2%) than in yearlings (36.5%, 51.5%) or calves (24.9%, 47.2%). The variation in the prevalence of both GI nematodes and flukes among management and age groups within systems can be used as an entry point towards rational use of anthelmintics for each management system. More studies on seasonal transmission pattern of all these parasites are required in order to design rational, economic and locally sustainable parasite control programmes.     

Indigestion in Young Calves. V. The Influence of Grass Silage and Fine Hay

In an experiment with 24 young calves, lasting 45 days, all were fed a high lactose milk replacer causing some diarrhoea. Eight calves received grass silage and 8 fine hay in addition, while 8 received no solid supplement to the milk replacer (NS). Somewhat more (P < 0.05) dry matter was ingested from silage than hay. Weight gain was similar on the 2 supplements and much greater (P < 0.001) than on NS. Both silage and fine hay reduced (P < 0.01) the frequency of diarrhoea, approximately to the same extent. Further, silage or hay gave higher pH (P = 6.0.01 and 0.02, respectively) and less gram positive cocci and rods in the rumen fluid, better developed ruminai papillae and heavier (P < 0.01) empty reticulo-rumens than NS. Some calves fed silage had ulcers in the rumen, the same having occurred on fine hay in earlier experiments, but not in the present one. Althogether, the 2 roughages gave very similar results.     

Herd-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria on dairy farms in Minnesota,USA

This study aimed to identify herd-level risk factors associated with fecal shedding of Shiga toxin-encoding bacteria (STB) on dairy cattle farms in Minnesota, USA. After adjustment for farm size, risk factors included: use of total mixed ration (TMR) for lactating dairy cows [odds ratio (OR) = 3.0; 95% confidence interval (CI): 1.8 to 5.1], no use of monensin for weaned calves (OR = 4.8, 95% CI: 2.5, 9.3), and no use of decoquinate for preweaned calves (OR = 2.2, 95% CI: 1.4, 3.6). Fecal shedding of STB was more common in small herds (< 100 cows, OR = 3.6, 95% CI: 2.1, 6.2) than in large herds (≥ 100 cows). Herd management factors related to cattle feeding practices were associated with fecal shedding of STB.     

Influence of Bos indicus crossbreeding and cattle age on apparent utilization of a high-grain diet

Ten Bos indicus x MARC III (initial BW = 303 +/- 25 kg) and 10 MARC III (initial BW = 322 +/- 16 kg) steers were used in a 2 x 2 factorial design to determine whether cattle age or Bos indicus crossbreeding influence site of digestion of a high-grain diet. Initially, five Bos indicus x MARC III and five MARC III steers were fitted with duodenal cannulas and adapted to a 95% concentrate diet that was offered for ad libitum consumption for a 237-d feeding period (calves). During the feeding period, duodenal and fecal samples were collected during 4-d periods beginning on d 14, 67, 137, and 228. The remaining 10 steers were fed a forage-based diet for a targeted daily gain of .6 to .7 kg for 210 d (yearlings). Following this period, yearling steers were duodenally cannulated and adapted to the 95% concentrate diet. Yearling steers had ad libitum access to feed for 165 d, and samples were collected during 4-d periods beginning on d 13, 42, 102, and 159. Dry matter intake was 9.8 and 7.6 kg/d and daily gain was 1.35 and 1.16 kg in yearlings and calves, respectively. Apparent OM digestion in the stomach was greater (P < .01) in yearlings than in calves. In contrast, postruminal disappearance as a percentage of OM intake was greater (P = .05) in calves than in yearlings. Duodenal flows of total N, microbial N, nonmicrobial N, and total amino acids and total tract N digestibility were not affected (P > .05) by age or Bos indicus crossbreeding. Fecal N excretion was greater (P < .01) in yearlings than in calves. Results of this experiment suggest little effect of Bos indicus influence on utilization of a high-grain diet. However, more feed is digested in the rumen of yearlings than of calves consuming a high-grain diet.     

The occurrence of Haemophilus somnus in feedlot calves and its control by postarrival prophylactic mass medication.

Three field trials were conducted in a large commercial feedlot in Saskatchewan to determine the prevalence of Haemophilus somnus in calves and to evaluate the efficacy of prophylactic mass medication with long-acting oxytetracycline on day 17 (1990, n = 1336), day 11 (1991, n = 4372), or day 8 (1992, n = 5632) postarrival. Hemophilosis accounted for > 40% of the mortality in feedlot calves each year. Haemophilus somnus was cultured from the blood of one febrile calf on day 1 (0.1%, n = 895), but it was not cultured from nasal swabs on day 1 or day 11 (n = 881) or from blood samples on day 11 (n = 883). Similarly, it was not cultured from nasal swabs or blood samples from sick calves first treated for bovine respiratory disease (BRD) (n = 219). Serological titers to H. somnus increased (p < 0.05) in unvaccinated calves from day 1 (Geometric mean titer = 11,846) to day 96 (Geometric mean titer = 63,712), indicating natural infection following feedlot entry. Calves that relapsed twice with BRD or died from BRD +/- hemophilosis had significantly (p < 0.06) lower titers to H. somnus on days 1 and 96 than those that did not relapse twice or die. Postarrival mass medication with long-acting oxytetracycline did not reduce (p > 0.05) the risk of hemophilosis mortality. However, it reduced (p < 0.05) the risk of BRD treatment by 14% and the risk of BRD mortality by 71%. Additional epidemiological studies of H. somnus are needed so that we can develop strategic medication and vaccination programs to reduce losses from hemophilosis.     

Comparison of efficacy of sulbactam: ampicillin to ampicillin and saline for treatment of experimentally induced Escherichia coli diarrhea in neonatal calves.

A study was conducted to compare the efficacy of sulbactam: ampicillin (SAMP) (3.3:6.6 mg/kg body weight (BW), IM, q24 h) to that of ampicillin trihydrate (AMP) (6 mg/kg BW, IM, q24 h) and 0.9% saline (SAL) (3 mL IM, q24 h) for the treatment of diarrhea in calves induced by oral inoculation with Escherichia coli strain B44 (O9:K30:K99:H-). Treatment was initiated when severe diarrhea was noted (T0) and continued for at least 3 d; or for 24 h after clinical signs resolved; or for a maximum duration of 7 d. Starting at T0, calves were examined twice daily: appetite; rectal temperature (TEMP); and fecal consistency (FECAL), mental status (ATTD), eye position (EYE), and skin elasticity (SKIN) scores were recorded. Feces collected at T0 were submitted for bacteriology, electron microscopy, and parasitology. A complete blood count was performed at T0 and T3 (24 h after third treatment). Severely dehydrated, depressed, and anorexic calves were euthanized and considered mortalities. Cause of death was determined by post mortem examination. A total of 30 calves were included in the study. Three calves were excluded from final analysis. E. coli strain B44 was cultured from feces of all calves at T0. At T2 (24 h after second treatment) mean TEMP of SAMP calves was significantly higher (P < 0.05) than mean TEMP of SAL calves; EYE and SKIN scores of SAMP calves were significantly lower (P < alpha beta = 0.025) than those of SAL and AMP calves; and ATTD and FECAL scores of SAMP calves were significantly lower (P < alpha beta = 0.025) than in SAL calves. At T3, SAMP calves had significantly lower (P < 0.05) mean hematocrit than SAL calves and lower mean total plasma protein concentration than AMP and SAL calves. Mean fibrinogen concentration in SAMP calves at T3 was significantly lower (P < 0.05) than that of calves receiving either SAL or AMP. The number of surviving SAMP calves (10/10) was significantly higher (P < alpha beta = 0.025) than the number of surviving SAL calves (2/9), but not significantly different from the surviving AMP calves (3/8).     

Risk Factors Associated with the Occurrence of Bovine Tuberculosis in Cattle in the Southern Highlands of Tanzania

A study was conducted in the Southern Highlands of Tanzania to determine the prevalence of bovine tuberculosis and the risk factors associated with the occurrence of the disease in cattle of different categories and in different climatic zones. The overall prevalence of the disease was 13.2%, and 51% of the herds tested contained reactor cattle. Assessment of risk factors was based on comparisons of the reactivity of the cattle in the single comparative intradermal tuberculin test (SCITT). Older cattle were more affected by the disease than yearlings and calves (p<0.0001). There were significant differences between male and female cattle (p<0.05) and between cattle with exotic blood compared to indigenous Short Horn Zebu (SHZ) cattle (p<0.05). The castrated bulls, often used for draught power, were more frequently (p<0.01) affected than the entire bulls, mainly used for breeding. Reactivity to tuberculin did not appear to be influenced by the reproductive status of the animal. The reactivity to tuberculin of pregnant cattle was not significantly different from that of the rest of the cows (p>0.05). However, significantly more (14.6%) lactating cattle reacted in the SCITT than did non-lactating cows (12.0%) (p<0.05). There was a highly significant difference (p<0.001) between reactivity in the SCITT among cattle grazing in the hot and dry lower lands (14.0%) and that in those grazing in the cool and wet highlands (8.7%).     

Increasing prevalence of Coxiella burnetii seropositive Danish dairy cattle herds

A study based on bulk tank milk samples from 120 randomly selected dairy cattle herds was conducted to estimate the prevalence of Coxiella burnetii seropositive dairy herds, to describe the geographical distribution, and to identify risk factors. Using the CHEKIT Q-fever Antibody ELISA Test Kit (IDEXX), the study revealed a prevalence of 79.2% seropositive herds, 18.3% seronegative herds, and 2.5% serointermediate herds based on the instructions provided by the manufacturer. Multifactorial logistic regression showed statistically significant associations (P < 0.01) between C. burnetii seropositivity and increasing herd size (OR = 1.02 per cow increment) and increasing regional average number of cattle per dairy herd (OR = 1.02 per animal increment). Herds >150 cows had 17.9 times higher odds of testing positive compared to herds <80 cows. The regional average number of cattle herds per square kilometer was borderline significantly related to the occurrence of seropositive dairy herds (P = 0.06). The results indicate an increased prevalence of seropositive dairy herds since the previous survey in 2008 and an adverse impact of increasing herd size and cattle density on the risk of seropositivity.     

The influence of supplemental chromium and vaccines on the acute phase response of newly arrived feeder calves.

The acute phase response as indicated by serum haptoglobin and total haemolytic complement activity (CH50) was measured in 72 cross-bred steer calves purchased at sales in Ontario. During the 28 day (d) trial, 18 steers were randomly assigned to each of the following groups: 1) control; 2) vaccinated (Infectious Bovine Rhinotracheitis, Parainfluenza-3, Bovine Viral Diarrhea, Bovine Respiratory Synctial Virus vaccine plus Pasteurella haemolytica vaccine); 3) supplemental chelated Cr (0.14 mg/kg); and 4) Cr plus vaccines. Haptoglobin concentrations were low at arrival, increased (P < 0.05) on day 7, and returned to near initial levels (P > 0.05) by day 14. Supplemental Cr reduced (P < 0.05) haptoglobin on day 7 when morbidity was highest. Following antibiotic treatment for respiratory disease haptoglobin was lower (P < 0.05) than during morbidity; however, during morbidity, haptoglobin concentrations were not greater in sick calves (P > 0.05) than in healthy calves. Complement activity was lowest on day 7 (P < 0.05) and peaked on day 14 (P < 0.05). Complement activity tended to be lower on day 7 for vaccine, Cr, and Cr+ vaccine groups; however, the difference from controls was not significant (P > 0.10). Complement activity did not increase on day 14 (P > 0.05) with Cr supplementation as in other treatments. Morbid calves had lower (P < 0.05) CH50 activity than healthy calves on day 14. Following antibiotic treatment, the Cr-supplemented group had higher (P < 0.05) CH50 than during morbidity. In general, chromium supplementation reduced the acute phase response in newly arrived feeder calves.     

Aspects of bovine herpesvirus 1 and bovine viral diarrhoea virus herd-level seroprevalence and vaccination in dairy and beef herds in Northern Ireland

Background

Infections with bovine herpesvirus 1 (BoHV-1) and bovine viral diarrhoea (BVD) virus cause diseases of cattle with a worldwide distribution. The primary objective of the present study was to describe aspects of herd-level BoHV-1 and BVDV seroprevalence (based on testing of pooled sera) and control on farms in Northern Ireland, including vaccine usage.An indirect antibody ELISA test (SVANOVA, Biotech AB, Uppsala, Sweden) was applied to serum pools which were constructed from serum samples taken for a cross-sectional study of a convenience sample of 500 Northern Irish dairy and beef cow herds in 2010, for which vaccination status was determined by telephone survey. The herd-level seroprevalence of BoHV-1 and BVDV in Northern Ireland was estimated in non-vaccinating herds and associations between possible risk factors (herd type and herd size (quartiles)) and herd-level prevalence were determined using chi-squared analysis.

Results

The herd-level seroprevalence (of BoHV-1 and BVDV) in non-vaccinating herds was 77.3% (95% CI: 73.6–80.9%) and 98.4% (95% CI: 97.3–99.5%) respectively in the cross-sectional study. A significant difference existed in BoHV-1 herd-level seroprevalence between dairy and beef herds (74.7% vs 86.5% respectively; p < 0.02) though not for BVDV seroprevalence (98.5% vs 98.3% respectively; p > 0.91). A significant association was found between herd size (quartiles) and herd-level classification for BoHV-1 herd-level seroprevalence based on cut-off percentage positivity (COPP) (p < 0.01) while no such association was found for BVDV (p = 0.22).15.5% and 23.8% of farmers used BoHV-1 and BVDV vaccines, respectively. BoHV-1 vaccine was used in 30% of dairy herds and in 11% of beef herds, while BVDV vaccine was used in 46% and 16% of dairy and beef herds, respectively.

Conclusions

The results from this study indicate that the true herd-level seroprevalences to bovine herpesvirus 1 and bovine virus diarrhoea virus in non-vaccinating herds in Northern Northern Ireland are 77.3% (95% CI: 73.6–80.9%) and 98.4% (95% CI: 97.3–99.5%), respectively. The present study will assist in guiding regional policy development and establish a baseline against which the progress of current and future control and eradication programmes can be measured.