Condition of bob veal calves on arrival at an abattoir in Ohio.

Previous research has shown surplus dairy calves arrive at 'formula-fed' veal operations in North America in sub-optimal condition; however, little is known about the condition of 'bob' veal calves on arrival at abattoirs. The objectives of this study were to assess the condition of bob veal calves on arrival at an abattoir in Ohio and determine risk factors for poor health outcomes. On arrival, 35 calves in each of 12 cohorts (n = 420 calves) were assessed using a standardised health examination. A blood sample was also collected to assess failed transfer of passive immunity (FTPI) and hypoglycaemia. Descriptive statistics were used to describe the prevalence of poor health outcomes. Mixed-effects logistic regression models were used to identify if calf breed, sex, or source were risk factors for poor health outcomes. The most common physical health concern observed on arrival at the abattoir was dehydration (mean: 68.6%), followed by thin body condition (39.8%), and navel inflammation (25.7%). Approximately one-quarter (23.4%) of calves had FTPI and 73.4% were hypoglycaemic. Male calves were more likely than females to arrive hypoglycaemic. Hydration status was associated with breed; Jersey and crossbreed calves were less likely to be dehydrated than Holstein-Friesian calves. Buying station tended to be associated with FTPI. These results underline the need for more studies investigating morbidity, mortality, and their underlying risk factors to promote calf welfare prior to slaughter in each stage of the production chain: on the dairy farm of birth, during marketing, and in transit.

Can calf age be estimated using a combination of serum gamma-glutamyl transferase, total protein and immunoglobulin G?

Our aim was to test a novel method for estimating the age of young calves, using serum γ-glutamyl transferase (GGT) activity, total protein concentration and immunoglobulin G (IgG) concentration. Blood samples were taken from 59 dairy calves at 2, 4, 6, 8, 10, 12, and 14 days of age, and serum GGT activity, total protein concentration, and IgG concentration were measured. Bayesian regression models were used to estimate the association of GGT, total protein, and IgG, with calf age. A multivariate hierarchical regression model was then created, and the model's reliability in estimating the age of simulated subjects was assessed. The univariate models showed a strong within-calf relationship between age and GGT (conditional R2 (cR2) = 0.93), and age and total protein (cR2 = 0.75), while the relationship between calf age and IgG was less consistent (cR2 = 0.63). There was a high degree of variation between calves for these parameters, particularly for the relationship between age and total protein (marginal R2 (mR2) 0.02), and age and IgG (mR2 0.01); somewhat less between-calf variation was seen for GGT (mR2 0.30). For the final multivariate model, we tested the model reliability by simulating new subjects. The credible intervals for estimates of calf age generated from the model were wide, indicating poor reliability. We concluded that single measurements of serum GGT activity, total protein concentrations and IgG concentrations cannot be used to reliably estimate the age of young calves to within 1-2 days.

Blood parameters of young calves at abattoirs are related to distance transported and farm of origin.

Nonreplacement dairy calves, or bobby calves, are fasted and transported to abattoirs from as young as 5 d of age in Australia. The aims of this cross-sectional observational study were (1) to assess the welfare status, as measured by blood parameters, of bobby calves in the commercial supply chain after transport and lairage, and (2) to assess whether distance and duration of transport are risk factors for poor bobby calf welfare, as measured by blood parameters. We hypothesized that bobby calves transported greater distances would be more likely to show evidence of compromised welfare, as measured by blood indicators of hydration, energy status, and muscle fatigue or damage. We also hypothesized that there would be a large amount of variability in indicators of energy status between calves from different farms. We analyzed blood samples collected at slaughter over a spring and an autumn calving period from 4,484 Australian bobby calves aged approximately 5 to 14 d old from 3 different states, after transport, fasting, and lairage. Packed cell volume (PCV), plasma glucose, and serum urea, total protein, ß-hydroxybutyrate (BHB), and creatine kinase (CK) were measured. Radio frequency identification ear tag data were used to estimate the distance that the calves were transported and to identify the farm of origin. Data were analyzed using linear mixed models, except for BHB, which was analyzed using a Goodman-Kruskal gamma test due to left censoring of the data. Twelve percent of calves showed evidence of anemia (PCV less than 0.23 L/L), and 11% had urea concentrations consistent with dehydration (urea more than 7.7 mmol/L). Thirty-six percent of calves had CK activity above normal resting values, and 1% of calves had CK >2,000 U/L, indicating muscle fatigue or damage. Distance transported had significant effects on all blood variables except urea and BHB. With increasing distance transported, calves were more likely to show evidence of a negative energy balance (low plasma glucose) or dehydration (high PCV or total protein). The estimated effect of distance overall was small, but for calves transported more than 500 km, plasma glucose concentration declined more per kilometer. The calves' farm of origin accounted for a reasonable amount of the random variation between calves for plasma glucose (20%). Our results suggest that longer transport distances may increase the risk of poor calf welfare (dehydration, negative energy balance) after transport, and on-farm calf management (e.g., nutrition, timing of feeding before transport) may affect transported calves' energy status; improving this area could result in better energy availability during fasting.

Biochemistry and hematology reference intervals for neonatal dairy calves aged 5-12 days.

BACKGROUND: Comprehensive hematology and biochemistry RIs are currently lacking in the literature for young dairy calves based on sample sizes more than 120. Young dairy calves are at a relatively high risk of poor health and welfare outcomes. They have a high risk of morbidity and mortality in the first 2 weeks of life, and many are transported and fasted during this time. For example, non-replacement calves in Australia and New Zealand are usually 5-12 days old when transported to abattoirs, meaning that calves of this age group are potentially at risk of both health and welfare compromise. Given these factors, sound, comprehensive, age-specific biochemical and hematologic RIs are needed for both veterinary clinical practice and to inform research on calf health and welfare. OBJECTIVES: The aim of this study was to generate age-specific hematology and biochemistry RIs for dairy calves aged 5-12 days. METHODS: We collected blood samples from 141 fasted, healthy dairy calves on 10 Australian farms. Reference Value Advisor software was used to calculate nonparametric RIs for multiple biochemistry and hematology variables. RESULTS: RIs for a panel of hematology and biochemistry variables in dairy calves aged 5-12 days old were derived. CONCLUSIONS: These RIs will be useful for clinical veterinary practice, as well as for research on dairy calf health and welfare.

Invited review: The welfare of young calves transported by road.

The transport of young calves is a welfare concern. Young calves aged ≤3 mo are particularly vulnerable to compromised welfare, and are at a relatively high risk of morbidity and mortality compared with adult cattle. Calves face several potential challenges to welfare during and after transport, including food and water deprivation, disease, injury, and stress from handling, social mixing, and new environments. The key risk factors identified for poor calf welfare associated with transport include long transport and fasting durations, young age at transport, poor colostral immunity, timing within the calving season, lack of bedding in trucks, and high stocking density. Maximizing calf welfare thus requires a multifaceted approach, such as minimizing transport and fasting durations, transporting at an appropriate stocking density with comfortable bedding, only transporting calves that are healthy and fit, and optimizing pre-transport calf management. More research is needed to understand the effect of transport on the mental or affective state of calves.

Blood collection from dairy calves at exsanguination post-slaughter yields similar biochemical and packed cell volume measurements compared with in vivo collection during lairage.

Blood collection at exsanguination is a method of collecting samples at abattoirs which itself has no effect on animal welfare, compared with collection prior to stunning. However, there is the potential for artefact to affect measurements. It was hypothesised that, for most blood analytes measured, the differences between lairage and exsanguination measurements would be minimal, except for creatine kinase, which was expected be higher in exsanguination samples. Fifty-nine male dairy calves approximately 5-10 days old were sampled prior to slaughter, and again during exsanguination after stunning. Each sample was analysed for packed cell volume, serum urea, beta-hydroxybutyrate, gamma-glutamyl transferase, total protein, glucose and creatine kinase concentrations. Exsanguination and lairage blood results were compared using a paired t-test. There were no significant differences between the measurements taken at exsanguination compared with lairage for packed cell volume, urea and beta-hydroxybutyrate. Glucose concentrations were higher in exsanguination samples, and total protein concentrations were lower, but for both of these analytes the differences were clinically small. Gamma-glutamyl transferase activity was lower in exsanguination samples compared with lairage samples. Creatine kinase activity was higher in exsanguination samples. It was concluded that collecting blood at exsanguination is a valid method for collecting samples for measurement of packed cell volume, urea, and beta-hydroxybutyrate in calves. Glucose and total protein can also yield useful measurements in these samples, though care needs to be taken with interpretation given the minor differences between exsanguination and lairage measurements. Exsanguination samples may be unsuitable for creatine kinase and gamma-glutamyl transferase measurement.