The effect of slow-release milk replacer feeding on health and behaviour parameters in dairy breed calves.

The aim of this research paper was to evaluate the effect of a slow-release milk replacer on health and behaviour of neonatal dairy calves. This was done with the potential benefits to welfare during transport in mind. A total of 15 calves were randomly divided into three groups of 5, namely, a control group fed twice in 24 h with 3 l of a conventional milk replacer, a slow-release group fed once in 24 h with 2 l of conventional milk replacer and 1 litre of a specialised micro-encapsulated feed and an enriched-replacer group fed once in 24 h with 3 l of milk replacer enriched with micellar casein. Blood samples were taken before feeding and 6, 12, 18 and 24 h after and analysed for acid-base parameters, electrolytes, glucose, haemoglobin, cortisol, insulin, cholecystokinin and adiponectin. Calf behaviour was recorded between 6 and 14 h after feeding. There was a significant increase in blood pH 6 h after feeding in all groups, but the glucose, HCO3 - and base excess increased significantly in the slow-release group only, whereas sodium increased significantly in the enriched group only. Glucose levels remained significantly higher in the slow-release group, relative to the control, at 6, 12, and 18 h after feeding. Insulin levels changed significantly over time in the enriched and control group but remained constant in the slow-release group. Insulin levels were significantly higher in the control group when compared to the slow-release group after feeding. Adiponectin changed significantly over time after feeding in the control group only, but no significant changes were observed between the feeding groups. Behavioural patterns were similar in control and slow release groups but less favourable (less lying time, more vocalisations) in the enriched group. In conclusion, once-daily feeding of slow-release milk replacer demonstrated favourable patterns of blood variables related to satiety and hunger as well as behavioural patterns that did not differ from conventional twice-daily feeding.

Evaluation of the optimal strong ion difference concentration of an oral electrolyte and buffering solution for the treatment of neonatal calf diarrhea.

An observational study was conducted to comparatively assess the efficacy of three different oral rehydration and buffering solutions, differentiated by their strong ion difference (SID) concentration, for treatment of neonatal calves with naturally acquired diarrhea. The SID concentrations tested were 100 mM, 170 mM and 230 mM for treatments SID100, SID170 and SID230, respectively. Clinical assessment and blood gas analysis were completed for 18 diarrheic calves once pre- and twice post- (6 and 24 hr after) oral administration with one of the three treatments. A repeated measure mixed model approach was used to analyze (a) the within-group efficacy of each treatment over time and (b) the between-group comparison at each timepoint. SID230 treatment resulted in a significant increase in blood pH, HCO3-, BE, SID and Na+ at 6 and 24 hr after treatment, and a significant decrease in AG and K+ by 24 hr after treatment. There were no significant changes in any of the blood gas parameters after treatment with SID100 and SID170. SID230 treatment also resulted in blood gas parameter changes that were significantly different to the other two groups. These results suggest that the optimum SID concentration for the treatment of calves with diarrhea is likely to be higher than current recommendations.

Determining the predictive capability of a Clinical Assessment Scoring Chart to differentiate severity of the clinical consequences of neonatal calf diarrhea relative to gold-standard blood gas analysis.

Neonatal calf diarrhea (NCD) is a major problem to calf health worldwide, in terms of both morbidity and mortality. A five-point ordinal scale clinical assessment scoring (CAS) chart was utilized to assess calves suffering from NCD-related clinical abnormalities (acidosis and dehydration) on commercial farms. The objective of this research was to determine the predictive capability of this CAS chart against gold standard blood gas parameters, designed to assist farmers in the accurate assessment of the clinical consequences of NCD. A total of 443 diarrheic and non-diarrheic calves were enrolled in the study. The CAS chart rated a calf's health from no clinical signs to varying degrees of clinical severity on a 0 (clinically normal) to 4 (grave) scale, based on clinical indicators including calf demeanour, ear position, mobility, suckle reflex, desire-to-feed, and enophthalmos. Blood gas analysis was conducted for individual calves, consisting of pH, base excess, Na+, K+, Ca2+, Cl-, glucose, total hemoglobin, bicarbonate, anion gap, and strong ion difference. Statistical evaluation was performed by comparison of the CAS score with blood gas profiles using ordinal logistic regression and a non-parametric estimation of the Receiver Operating Characteristics (ROC). The ROC analysis indicated that the CAS chart had acceptable specificity (>95%) with low sensitivity (<60%) in differentiating clinically normal from acidotic/dehydrated cases. Assessment of individual severity classes indicated that the chart can predict and differentiate both clinically normal and advanced cases from the other severity classes (peak estimations >80%) but had reduced accuracy in differentiating mild and moderate cases (peak estimations >50%). The chart, as presented, provides a simple tool to differentiate clinically normal from calves suffering the consequences of diarrhea, but fails to accurately differentiate severity for NCD related acidosis and dehydration. Further efforts are required to enhance the sensitivity and differential diagnostic value of this type of chart.

Liver fluke in Irish sheep: prevalence and associations with management practices and co-infection with rumen fluke.

BACKGROUND: The present study aimed to identify the national prevalence of Fasciola hepatica in Irish sheep and to conduct a risk analysis assessment based on management and treatment practices in participating flocks. Also, co-infection with rumen fluke was quantified and its association with liver fluke and management practices was assessed. METHODS: A total of 305 sheep flocks were selected ensuring even national representation of the sheep population. Participating farms were asked to complete a survey questionnaire on farm management practices and submit faecal samples during the winter of 2014-2015. Pooled faecal samples were analysed for the presence of F. hepatica and co-infection with rumen fluke. Apparent and true prevalence were calculated, additionally, the rate of co-infection with rumen fluke was also obtained. Correlation and regression analyses were used for assessing associations between management practices, liver fluke infection and co-infection with rumen fluke. RESULTS: The national true prevalence of F. hepatica was 50.4% (n = 305). Regional prevalence varied from 41% in the east to 52% in the south. Co-infection with rumen fluke was observed in 40% of the studied population and correlated with increased F. hepatica egg counts (OR = 2.9; P ≤ 0.001). Predominant breeds were Suffolk, Texel and Horned Mountain breeds. Beef cattle were the most frequent type of other livestock present on farms and mixed species grazing was frequently reported (73%). More than half of the flocks reported a mid-to-late lambing period (March-April). Use of mountain land for grazing was of 32%. Flukicides were most commonly used twice over the autumn-winter period. Regression analyses highlighted significant association of F. hepatica status, with the presence of other livestock on farm, frequency of flukicides used during the winter and clinical presentation of liver fluke. A significant increase in eggs per gram of faeces was observed in Charollais sheep in comparison with all other breeds. Co-infection with F. hepatica and Calicophoron daubneyi was also significantly associated with the presence of other livestock on the farm, type of flukicide used and clinical fasciolosis. CONCLUSIONS: The present study provides up-to-date information on the prevalence of F. hepatica in Irish sheep and adds insight to the epidemiology of the disease. These findings will be useful for designing new holistic control measures for F. hepatica infection.

Establishing blood gas ranges in healthy bovine neonates differentiated by age, sex, and breed type.

Calf mortality and morbidity commonly occurs within the first month of life postpartum. Standard health ranges are invaluable aids in diagnostic veterinary medicine to confirm normal or the degree and nature of abnormal parameters in (sub)clinically ill animals. Extensive research has indicated significant differences between the physiologies of neonate and adult cattle, particularly for blood parameters such as pH, base excess, anion gap, and bicarbonate (HCO3-). The objective of this research was to determine the influence of age, sex, and breed type, in addition to environmental factors, on the normal blood gas profiles of neonatal calves, and thus develop a scientifically validated reference range accounting for any significant factors. The study was conducted on healthy neonatal calves (n = 288), and completed over a 2-yr period. Individual calf blood gas analysis was conducted for parameters of pH, base excess, Na+, K+, Ca2+, Cl-, glucose, total hemoglobin, HCO3-, pCO2, anion gap, strong ion difference, and hematocrit levels. Regression procedures examined the combined effect of year, farm, age, breed type, sex, and hours postfeeding on each variable. Significant effects were observed for age, sex, and breed type on several of the blood gas variables. Furthermore, year, farm, and hours postfeeding appeared to have less of an influence on neonatal bovine blood gas profiles. Consequently, specific ranges based on the neonate's age, sex, and breed type will allow for more detailed and accurate diagnosis of health and ill health in neonatal calves.

Genetic correlations between endo-parasite phenotypes and economically important traits in dairy and beef cattle.

Parasitic diseases have economic consequences in cattle production systems. Although breeding for parasite resistance can complement current control practices to reduce the prevalence globally, there is little knowledge of the implications of such a strategy on other performance traits. Records on individual animal antibody responses to Fasciola hepatica, Ostertagia ostertagi, and Neospora caninum were available from cows in 68 dairy herds (study herds); national abattoir data on F. hepatica-damaged livers were also available from dairy and beef cattle. After data edits, 9,271 dairy cows remained in the study herd dataset, whereas 19,542 dairy cows and 68,048 young dairy and beef animals had a record for the presence or absence of F. hepatica-damaged liver in the national dataset. Milk, reproductive, and carcass phenotypes were also available for a proportion of these animals as well as their contemporaries. Linear mixed models were used to estimate variance components of antibody responses to the three parasites; covariance components were estimated between the parasite phenotypes and economically important traits. Heritability of antibody responses to the different parasites, when treated as a continuous trait, ranged from 0.07 (O. ostertagi) to 0.13 (F. hepatica), whereas the coefficient of genetic variation ranged from 4% (O. ostertagi) to 20% (F. hepatica). The antibody response to N. caninum was genetically correlated with the antibody response to both F. hepatica (-0.29) and O. ostertagi (-0.67); a moderately positive genetic correlation existed between the antibody response to F. hepatica and O. ostertagi (0.66). Genetic correlations between the parasite phenotypes and the milk production traits were all close to zero (-0.14 to 0.10), as were the genetic correlations between F. hepatica-damaged livers and the carcass traits of carcass weight, conformation, and fat score evaluated in cows and young animals (0.00 to 0.16). The genetic correlation between F. hepatica-damaged livers in cows and milk somatic cell score was 0.32 (SE = 0.20). Antibody responses to F. hepatica and O. ostertagi had favorable genetic correlations with fertility traits, but conversely, antibody response to N. caninum and F. hepatica-damaged livers were unfavorably genetically correlated with fertility. This study provides the necessary information to undertake national multitrait genetic evaluations for parasite phenotypes.

Is TB Testing Associated With Increased Blood Interferon-Gamma Levels?

The Republic of Ireland reports a relatively low prevalence of Johne's disease (JD) compared to international counterparts. Postulated reasons for this include a lower average herd size and a grass-based production system. Ireland also engages in high levels of bovine tuberculosis (bTB) testing. As interferon-gamma (IFN-γ) is believed to play a key role in protecting against JD, it is our hypothesis that administration of purified protein derivative (PPD), as part of the bTB test, is associated with a systemic increase in IFN-γ production, which may potentially limit clinical progression of the disease. We studied 265 cows (202 Friesian and 63 "Non-Friesian," e.g., JerseyX, Norwegian Red) to assess IFN-γ levels and Mycobacterium avium subspecies paratuberculosis (MAP) antibody response before and after the bTB test. As part of the compulsory annual bTB test, avian and bovine PPD were administered at two separate cervical sites. To assess IFN-γ production, blood samples were taken before and 72 h after PPD administration. MAP antibody response was assessed before and 10 days post-PPD administration. A significant increase in MAP antibody response was identified post-bTB compared to pre-bTB response (p < 0.001). Additionally, IFN-γ production significantly increased at the post-bTB time point (p < 0.001) compared to the pre-bTB test readings. This may indicate a beneficial effect of bTB testing in controlling JD.

Associations between exposure to bovine herpesvirus 1 (BoHV-1) and milk production, reproductive performance, and mortality in Irish dairy herds.

As cost-benefit analyses are required to prioritize and promote disease control and eradication programs within a jurisdiction, national data relating to disease-related production losses are particularly useful. The objectives of the current study were to use Irish bovine herpesvirus 1 (BoHV-1) prevalence data in dairy herds, obtained by bulk milk sampling on 4 occasions over the 2009 lactation, to document associations between milk production, fertility performance, mortality, and BoHV-1 herd status. Bulk milk (n = 305) antibody ELISA was used to classify farms as positive or negative in terms of endemic BoHV-1. Cow-level (milk parameters only) and herd-level performance data were sourced from the Irish Cattle Breeding Federation. Ordinary linear and negative binomial regressions were used to investigate associations between milk, fertility, and mortality performance and herd-level BoHV-1 results (both categorical and continuous variables). Only slight effects on the rates of carryover cows, nonpregnant cows, and total deaths were highlighted with increasing ELISA sample/positive (%) values (incidence rate ratio = 1.001). Multiparous cows in herds BoHV-1 bulk milk antibody positive recorded a reduction in milk yield per cow per year of 250.9 L in the multivariable linear model. Milk fat and protein yields were also affected by herd BoHV-1 status, again highlighting sub-optimal milk production in BoHV-1 bulk milk-positive herds. The current study has highlighted an economical method of investigating losses due to endemic infection using repeated bulk milk sampling over a single lactation. These data can contribute to analyzing the cost-benefit of applying BoHV-1 control strategies both on farm and at a national level.

An observational study using blood gas analysis to assess neonatal calf diarrhea and subsequent recovery with a European Commission-compliant oral electrolyte solution.

An observational study was conducted on dairy calves (51 healthy, 31 with neonatal diarrhea) during outbreaks of diarrhea on 4 dairy farms. Clinical assessment scores (CAS) were assigned to each healthy and diarrheic calf [from 0 (healthy) to 4 (marked illness)]. Blood gas analysis [pH, base excess (BE), Na(+), K(+), Ca(2+), Cl(-), glucose, total hemoglobin, standard HCO3(-), strong ion difference (SID), and anion gap (AG)] was completed for each calf. Repeated measurements were taken in healthy animals, and pre- and postintervention measurements were taken for diarrheic calves. The mean CAS of diarrheic calves was 1.7, with 51, 30, 17, and 2% of calves scoring 1, 2, 3, and 4, respectively. The mean value for blood pH, BE, AG, and SID was 7.26, -4.93mM, 16.3mM, and 38.59mM, respectively. Calves were administered an oral rehydration and buffering solution (ORBS; Vitalife for Calves, Epsilion Ltd., Cork, Ireland) and reassessed. The mean CAS decreased to 0.38 (65% of calves scored 0 and 35% scored 1) at 6 to 18h posttreatment and to 0.03 (98% of calves scored 0 and 2% scored 1) within 24 to 48h. Significant increases in mean value for pH, BE, HCO3(-), Na(+), and SID, and significant decreases in AG, K(+), Ca(2+), and total hemoglobin were recorded posttreatment. The correlation estimates indicated that pH, HCO3(-), and BE were strongly correlated with CAS, with values exceeding 0.60 in all cases. Administration of an ORBS with a high SID and bicarbonate buffer demonstrated rapid recovery from a diarrheic episode in dairy calves.

Prevalence of BoHV-1 seropositive and BVD virus positive bulls on Irish dairy farms and associations between bull purchase and herd status.

BACKGROUND: BVD and IBR are contagious viral diseases highly prevalent in Irish cattle. Despite their significant reproductive and economic impact very little is known about the BVD and IBR status of stock bulls (a bull used for breeding purposes). There are still a high proportion of dairy farms in Ireland that rely on the use of a bull for breeding cattle and ensuring the fertility of the bulls is of paramount importance for the efficiency of the farms. The prevalence of BoHV-1 and BVD in stock bulls in Irish dairy herds has never been investigated. The objectives of this study therefore were: (i) to provide descriptive, observational data on the use of stock bulls on Irish dairy farms; (ii) to investigate the BVD and BoHV1 status of a sub-set of stock bulls; (iii) to investigate factors associated with BVD and BoHV1 status of stock bulls and (iv) to investigate factors associated with dairy herd status for BVD and BoHV1, including any associations with the use of stock bull. A total of 529 blood samples from bulls involved in the dairy breeding process were analysed for BVD virus using RT-PCR, and BoHV-1 antibodies by ELISA test. A total of 305 different dairy herds took part in the study and the overall BVD and BoHV-1 herd status was determined by ELISA using four bulk tank milk samples over the 2009 lactation. Logistic regression was used to investigate the associations between the stock bulls and BVD and BoHV-1 herd and individual status. RESULTS: Of the 305 total participating farms, 235 farms (77 %) had at least one bull and 167 farms had purchased bulls. Two bulls (0.4 %) out of 529 tested were found positive for BVD virus and 87 (16.7 %) tested seropositive for BoHV-1. Some significant associations were identified between the purchase of bulls and both viral diseases. Purchased bulls were three times more likely to be seropositive for BoHV-1 than homebred bulls. In the same way, herds with purchased bulls were three times more likely to be classified as seropositive for BVD and four times more likely to have evidence of recent BoHV-1 circulation than farms where all the bulls were homebred. CONCLUSIONS: The prevalence of BoHV-1 and BVD in stock bulls in Irish dairy herds has never been investigated. This study highlights the widespread use of stock bulls in Irish dairy herds, as well as the high rate of exchange of bulls between farms. Significant associations were found between the origin of the bull and their serological BoHV-1 status. In keeping with these results, bulls with higher number movements between farms were more likely to be seropositive for BoHV-1.

Impact of three inactivated bovine viral diarrhoea virus vaccines on bulk milk p80 (NS3) ELISA test results in dairy herds.

Bovine viral diarrhoea virus (BVDV) is endemic in many countries and vaccines are used as a component of control and eradication strategies. Surveillance programmes to detect exposure to BVDV often incorporate the use of bulk milk (BM) testing for antibodies against BVDV p80 (NS3), but vaccination can interfere with these results. The aim of this study was to evaluate whether BVDV vaccines would confound BM testing for specific antibodies in a nationally representative group of commercial dairy farms in the Republic of Ireland. A total of 256 commercial dairy herds were included in the statistical analysis. Quarterly BM or serum samples from selected weanling heifers (unvaccinated homeborn youngstock) were assessed by ELISA for antibodies against the BVDV p80 subunit and whole virus. Wilcoxon rank-sum and receiver operating characteristic (ROC) analyses were used to examine differences among groups vaccinated with one of three commercially available inactivated BVDV vaccines. Two of the three vaccines showed evidence of interference with ELISA testing of BM samples. ROC analysis highlighted that one vaccine did not reduce the discriminatory power of the BVDV p80 ELISA for identification of herds with evidence of recent BVDV circulation, when compared with unvaccinated herds; thus, administration of this vaccine would allow uncomplicated interpretation of BM ELISA test results in vaccinated seropositive herds. Seasonal differences in BM antibody results were identified, suggesting that the latter half of lactation is the most suitable time for sampling dairy herds containing predominantly spring calving cows. The results of the present study are likely to prove useful in countries allowing vaccination during or following BVDV eradication, where BM testing is required as part of the surveillance strategy.

The Single Intradermal Cervical Comparative Test Interferes with Johne's Disease ELISA Diagnostics.

Enzyme-linked immunosorbent assays (ELISA) of milk and serum samples are a routinely used method of screening herds for Mycobacterium avium subspecies paratuberculosis (MAP). Infection with MAP causes granulomatous enteritis of ruminants known as Johne's disease (JD). The sensitivity (Se) and specificity (Sp) of MAP ELISAs leads to difficulties in the identification of both infected and infectious animals. Interference with MAP ELISA Se and Sp has been reported in MAP seronegative cows following administration of purified protein derivative (PPD) as part of intradermal testing for bovine tuberculosis (bTB). The aim of this study is to examine the impact of the single intradermal cervical comparative test (SICCT) for bTB, on both serum and milk MAP ELISA tests, in a herd containing both seropositive and seronegative cows pre-SICCT. A secondary objective is to provide appropriate timing of JD ELISA tests in relation to the SICCT. A herd of 139 cows were serum and milk sampled pre- and post-SICCT administration. Prior to SICCT, 6% of the herd tested seropositive for MAP using milk ELISA, with 8% positive on serum. ID Screen Paratuberculosis Indirect Screening Test (ID Vet) was used to screen the herd. Within 14 days of PPD administration, a significant increase in the prevalence of seropositive cows was recorded. Identical prevalence's were recorded with both test matrices (39%). ELISA values remained significantly higher until day 43 post-SICCT in milk (P = 0.850), and day 71 in serum (P = 0.602). If the "new" positives detected post-bTB testing are deemed false positives due to generation of cross-reacting antibodies by administration of PPD, milk would appear a more suitable sample for JD ELISA testing within 2 months of SICCT. In summary, sampling for JD utilizing milk ELISA should be avoided in the 43-day period following PPD administration, with serum ELISA sampling avoided for an additional 28 days.

A survey of management practices on Irish dairy farms with emphasis on risk factors for Johne's disease transmission.

BACKGROUND: Johne's disease (JD) is a chronic granulomatous enteritis affecting ruminants. A number of farm management practices are associated with increased risk of JD transmission. The aim of the current study was to document JD-related management practices currently employed on Irish dairy farms. Survey questions focused on calving area (CA), calf and manure management. Independent variables (region, calving-season, enterprise type, herd size and biosecurity status) were used to examine influences on JD associated dependent variables (survey questions). Additionally general biosecurity practices were also examined. RESULTS: Results showed management practices implemented by Irish dairy farmers pose a high risk of JD transmission. Of the farmers surveyed, 97% used the CA for more than one calving, 73.5% and 87.8% pooled colostrum and milk respectively, 33.7% never cleaned the CA between calving's, and 56.6% used the CA for isolating sick cows. Survey results also highlighted that larger herds were more likely to engage in high risk practices for JD transmission, such as pooling colostrum (OR 4.8) and overcrowding the CA (OR 7.8). Larger herds were also less likely than smaller herds to clean the CA (OR 0.28), a practice also considered of risk in the transmission of JD. CONCLUSION: Many management practices associated with risk of JD transmission were commonly applied on Irish dairy farms. Larger herds were more likely to engage in high risk practices for JD transmission. Control programmes should incorporate educational tools outlining the pathogenesis and transmission of JD to highlight the risks associated with implementing certain management practices with regard to JD transmission.