Large Animal Medicine: Advances in Calf Health

In all bovine production systems, neonatal calf diarrhea remains worldwide an important issue of economic losses and animal welfare. The aim of the present study was to identify risk factors for neonatal calf diarrhea as a herd health problem on Bavarian dairy farms. For the purpose of this study, management factors related to calf health were retrospectively compared between 59 dairy farms with calf diarrhea as a herd problem with those of 18 control farms, where no veterinary treatment of calves for neonatal calf diarrhea took place for at least one year prior to the farm visit. A multivariable binary logistic regression analysis of management factors indicated that administration of 3 L or more of colostrum at the second feeding after birth (Odds ration [OR] = 0.21, 95% confidence interval [95% CI] = 0.05–0.89), ad libitum feeding of milk during the first week of life (OR = 0.06, 95% CI = 0.006–0.60), and administration of an iron containing preparation after birth (OR = 10.9, 95% CI = 1.25–95.6) were independently associated with the presence of a herd problem with neonatal diarrhea. Results of this study therefore suggest that a higher plane of nutrition is a protective factor with regard to the occurrence of neonatal diarrhea on Bavarian dairy farms. These findings support the establishment of ad libitum feeding programs in dairy calf rearing. Full article

Several aspects of postnatal pulmonary adaption in the bovine neonate remain unclear, particularly the dynamics and regional ventilation of the lungs. We used electric impedance tomography (EIT) to measure changes in ventilation in the first 3 weeks of life in 20 non-sedated neonatal calves born without difficulty in sternal recumbency. Arterial blood gas variables were determined in the first 24 h after birth. Immediately after birth, dorsal parts of the lungs had 4.53% ± 2.82% nondependent silent spaces (NSS), and ventral parts had 5.23% ± 2.66% dependent silent spaces (DSS). The latter increased in the first hour, presumably because of gravity-driven ventral movement of residual amniotic fluid. The remaining lung regions had good ventilation immediately after birth, and the percentage of lung regions with high ventilation increased significantly during the study period. The centre of ventilation was always dorsal to and on the right of the theoretical centre of ventilation. The right lung was responsible for a significantly larger proportion of ventilation (63.84% ± 12.74%, p < 0.00001) compared with the left lung. In the right lung, the centrodorsal lung area was the most ventilated, whereas, in the left lung, it was the centroventral area. Tidal impedance changes, serving as a surrogate for tidal volume, increased in the first 3 weeks of life (p < 0.00001). This study shows the dynamic changes in lung ventilation in the bovine neonate according to EIT measurements. The findings form a basis for the recognition of structural and functional lung disorders in neonatal calves. Full article

Calf morbidity and mortality rates are often high in dairy herds, raising animal welfare concerns and negatively affecting farm economic efficiency and future performance. Disease prevention is critical to maintain calves in good health, but interventions are dependent upon the persons conducting them. This paper explores the perceptions of farmers, farm workers, veterinarians, and other advisors on the management of calfhood disease on dairy farms in England. Participants were recruited using purposive and “snowball” sampling, resulting in 40 in-depth, semi-structured interviews—26 with dairy farmers and 14 with advisors. Interviews were recorded, transcribed, and thematically coded. Three major themes were derived on the basis of interview data: disease occurrence and treatments, management of calf environment, and the role of stockmanship and perceived control. Respiratory and gastrointestinal diseases in calves were those reported to be most problematic on dairy farms. Limited time and financial resources caused some farmers and advisors to experience a perceived inability to control calf health without antimicrobial treatments. Overall, the findings emphasise the importance of human influences on calf health and disease in the context of influencing the interactions among the host, pathogens, and the environment. Further research should investigate what “attention to detail” means within different farm contexts and practices, as this was believed to be important in the promotion of better husbandry standards and health. We recommend the use of supportive knowledge exchange processes, including facilitation, to empower farmers to promote continuous improvement in calf health. Full article

Calf housing is naturally thermodynamic, with interactions between various elements such as wind speed, air temperature, and humidity. This study investigated the effect of the proportion of time for which calves were exposed to effective environmental temperatures below their lower critical temperature (LCT) on their daily liveweight gain (DLWG) within their first month of life. This study used the naturally occurring climatic environment, whereas other such studies have been conducted under climatically controlled conditions. Air temperature (°C), relative humidity (%), and wind speed (m/s) were recorded within the calf housing from birth until approximately 28 days of age, with calves being health-scored and weighed at regular intervals. Calves were housed from birth until 6–14 days old in individual hutches, and then moved into group housing igloo pens. Whilst individually housed, calves that spent less than 32% of their time below their LCT had a DLWG of 0.06 ± 0.34 kg/d (mean ± SE) compared to calves that spent more than 97% of their time below their LCT, which had a DLWG of −0.19 ± 0.045 kg/d. When group housed, calves that spent less than 1% of their time below their LCT had a DLWG of 0.59 ± 0.18 kg/d, whereas calves that spent more than 28% of their time below their LCT had a DLWG of 0.53 ± 0.23 kg/d. The proportion of time for which calves were exposed to effective environmental temperatures below their LCT had a significant effect on DLWG when calves were individually housed. Therefore, exposure to effective environmental temperatures below the LCT can be detrimental to the growth of the calf in the early stages of its life. Full article

Fatty acids are known for their regulatory role in inflammation and oxidative stress. The present study investigated 38 calves born from dams, abomasally supplemented with coconut oil, essential fatty acids (EFA), conjugated linoleic acid (CLA) or EFA + CLA, according to immunological traits and the oxidative and anti-oxidative status for the first 5 days of life. On day 2 of life, plasma total bilirubin, cholesterol, interleukin 1-β and ferric ion reducing anti-oxygen power (FRAP) were lower in calves with than without maternal EFA supplementation, and FRAP additionally on day 4. On day 3, the concentrations of reactive oxygen metabolites were higher in calves with than without maternal EFA supplementation and additionally on day 5 together of retinol. Total leucocyte counts were decreased in the EFA group compared to the CLA group on day 5. Lymphocyte proportions decreased from day 1 to 5 only in the EFA + CLA group. On day 2, plasma total protein was higher in CLA and EFA + CLA than in EFA calves. Similarly, CLA calves had higher interleukin 1-β concentrations compared to EFA + CLA calves. FRAP was decreased by CLA on day 4. Overall, the maternal fatty acid supply affected the inflammatory response and the oxidative and anti-oxidative status of the neonatal offspring. Full article

The first few months of life are of great importance to the longevity and lifetime performance of dairy cows. The nutrition, environment and healthcare management of heifer calves must be sufficient to minimise exposure to stress and disease and enable them to perform to their genetic potential. Lack of reporting of farm management practices in Northern Ireland (NI) makes it difficult to understand where issues impacting health, welfare and performance may occur in the rearing process. The objective of this study was to investigate housing design and management practices of calves on 66 dairy farms across NI over a 3-month period and also identify areas that may cause high risk of poor health and performance in dairy calves. An initial survey was used to detail housing and management practices, with two subsequent visits to each farm used to collect animal and housing-based measurements linked to hygiene management, animal health and performance. Large variations in key elements such as weaning criteria and method, calf grouping method used, nutritional feed plane, and routine hygiene management were identified. The specification of housing, in particular ventilation and stocking density, was highlighted as a potential limiting factor for calf health and performance. Lack of measurement of nutritional inputs, hygiene management practices and calf performance was observed. This poses a risk to farmers’ ability to ensure the effectiveness of key management strategies and recognise poor calf performance and health. Full article

The prevention of bovine respiratory disease is important, as it may lead to impaired welfare, economic losses, and considerable antimicrobial use, which can be associated with antimicrobial resistance. The aim of this study was to describe the prevalence of respiratory viruses and to identify risk factors for their occurrence. A convenience sample of 764 deep nasopharyngeal swab samples from veal calves was screened by PCR for bovine respiratory syncytial virus (BRSV), bovine parainfluenza-3 virus (BPI3V), bovine coronavirus (BCoV), influenza D virus (IDV), and influenza C virus (ICV). The following prevalence rates were observed: BRSV, 2.1%; BPI3V, 3.3%; BCoV, 53.5%; IDV, 4.1%; ICV, 0%. Logistic mixed regression models were built for BCoV to explore associations with calf management and housing. Positive swab samples were more frequent in younger calves than older calves (>100 days; p < 0.001). The probability of detecting BCoV increased with increasing group size in young calves. Findings from this study suggested that young calves should be fattened in small groups to limit the risk of occurrence of BCoV, although an extended spectrum of risk factors for viral associated respiratory disorders such as nutritional aspects should be considered in future studies. Full article

Failure of transfer of passive immunity (FTPI) due to inadequate ingestion of colostral immunoglobulins by calves is associated with increased mortality and morbidity risks. Feeding calves a sufficient amount of quality-tested colostrum within the first hours of life is essential for successfully transferring passive immunity. Many farms have implemented a second meal of colostrum to maximize the opportunities for passive immunity transfer. However, excellent passive immunity can be achieved with a single feeding of sufficient quality-tested colostrum. Moreover, there is currently no evidence demonstrating the impact of a second colostrum feeding within 24 h of life in calves receiving adequate volumes of quality-tested colostrum in an initial feeding. Hence, the objective of this retrospective cohort study was to compare the risks of FPTI, pre-weaning morbidity and mortality, and growth and performance between dairy calves that received one or two feedings of colostrum. For this, the health and production records of a large dairy herd were analyzed. At this farm, newborn calves receive 3 L of quality-tested colostrum soon after birth, followed by another 2 L 5–6 h later. However, at times of shortages of colostrum, calves only receive the initial 3 L meal. The records of 2064 male and 2272 female calves were analyzed, where 4156 and 180 calves received 2 and 1 colostrum meals, respectively. Data from both sexes were included in the analysis of the risks of FTPI, morbidity, and mortality; however, only data from heifer calves were utilized for growth and performance analysis. Survival analysis, and logistic and linear regression models were used to investigate the impact of receiving two feedings of colostrum on calf FTPI status, morbidity, mortality, reproductive indices, pre-weaning average daily gain (ADG), and first lactation 305-d Mature Equivalent milk production (305ME). Calves that received two feedings of colostrum had lower odds of FTPI, a lower probability of being treated for respiratory disease, diarrhea, or any disease, and a greater pre-weaning ADG. However, there was no association between the number of colostrum feedings and pre-weaning mortality, and the probabilities of first insemination and first calving, although heifers receiving two colostrum feedings tended to receive fewer inseminations and to have a greater first lactation 305ME. Collectively, our results suggest that feeding calves a second feeding of colostrum 5–6 h after the initial feeding soon after birth could be an effective strategy to decrease FTPI and morbidity and optimize ADG in dairy calves pre-weaning. Full article

Housing management of dairy calves is one of the factors that contributes to a successful rearing outcome. Individual housing of pre-weaned calves is thought to provide enhanced biosecurity and easier monitoring of the individual, and so remains prevalent in the UK. Behavioural studies have, however, found that pair housing is important for social learning, with positive impacts on health and welfare. This study utilised a single UK commercial dairy farm to establish if individual housing, pair housing from birth, or pair housing from three weeks of age affected health and behavioural parameters. Calves were housed in these allocated groups from birth to eight weeks of age, when they were moved into group pens of five calves for weaning at 10 weeks of age. All management routines other than the housing group were the same for enrolled calves. One hundred Holstein calves were recruited over a six-month period, and systematically allocated to a housing group. Weekly visits were conducted up to 10 weeks of age (weaning) for each calf, with weight, solid feed intake, and presence of clinical disease measured. In addition, a novel object approach test was carried out at six weeks, and a thoracic ultrasound was performed at seven weeks. Housing group had no effect on the average daily liveweight gain (ADLG) (p = 0.74), with an average of 0.66 kg/day over the pre-weaning period. However, on group housing at 8–10 weeks of age, there was a numerical increase in ADLG in the pair housed calves compared to the individually housed calves over the weaning period. Housing group had no significant effect on disease prevalence (p = 0.98) or the time taken to approach the novel object (p = 0.29). However, pair housed calves had increased mean total solid feed intakes from weeks 2–8 (p = 0.011), with 6.2 ± 0.67 kg (standard error of the mean—SEM), 12.7 ± 0.73 kg and 13.6 ± 0.70 kg ingested by individually housed, pair housed from birth and pair housed from three weeks of age, respectively. The overall findings of this study indicate that within a UK commercial dairy management system, there is no detrimental effect of housing calves within pairs (either from birth or three weeks of age) compared to individual housing. Full article

Dairy heifer calves experience high levels of contagious disease during their preweaning period, which may result in poor welfare, reduced performance or mortality. We determined risk factors for disease in a cohort study of 492 heifers recruited from 11 commercial UK dairy farms. Every animal received a weekly examination by a veterinarian from birth to nine weeks using the Wisconsin scoring system. Multivariable models were constructed using a hierarchical model with calf nested within farm. Outcome variables for each disease included a binary outcome (yes/no), disease duration and a composite disease score (CDS) including both severity and duration. Diarrhoea, bovine respiratory disease (BRD) and umbilical disease were recorded in 48.2%, 45.9% and 28.7% of calves, respectively. A higher heifer calving intensity in the week of birth reduced the CDS for diarrhoea, with a marginal benefit of improved passive transfer (serum immunoglobulin G (IgG) measured at recruitment). The CDS for BRD was reduced by housing in fixed groups, higher mean temperature in month of birth, increasing milk solids fed, increasing IgG, and higher plasma IGF-1 at recruitment. Conversely, higher calving intensity and higher temperature both increased the CDS for umbilical disease, whereas high IGF-1 was again protective. Although good passive transfer reduced the severity of BRD, it was not significant in models for diarrhoea and umbilical disease, emphasising the need to optimise other aspects of management. Measuring IGF-1 in the first week was a useful additional indicator for disease risk. Full article

Platelet and leukocyte count reference intervals (RIs) for cattle differ by age and while adult RIs are known, RIs for calves are studied less. The aims of this observational study are to evaluate variation of platelet counts of Holstein Friesian calves over the first 14 days of life and to propose RIs for platelet and leukocyte counts of Holstein Friesian calves aged 0–60 days. In a longitudinal study, 19 calves were blood sampled 17 times, in the first 14 days of their lives. Blood was collected in a citrate blood tube and platelet counts were determined. We assessed the course of platelet counts. In a field study, 457 healthy calves were blood sampled once. Blood was collected in an EDTA blood tube and platelet and leukocyte counts were determined. The RIs were calculated by the 2.5 and 97.5 percentiles. Platelet counts started to increase 24 h after birth (mean platelet count 381 × 10⁹/L ± 138 × 10⁹/L) and stabilized after five days (mean platelet count 642 × 10⁹/L ± 265 × 10⁹/L). In calves up to six days of age, platelet counts were lower than in calves older than five days. In conclusion, the RIs of platelet and leukocyte counts in calves were wider in range than the RIs for adult cattle, therefore, calf specific RIs for platelet and leukocyte counts should be used. From 6 until 60 days of age, we propose an RI for platelet counts of 287–1372 × 10⁹/L and for the first 60 days of life an RI for leukocyte counts of 4.0–18.9 × 10⁹/L. Full article

The “outdoor veal calf” system was developed to encounter the demand for a veal fattening system that allows for reducing antimicrobial use without impairing animal welfare. Management improvements including direct purchase, short transportation, vaccination, three-week quarantine in individual hutches, and open-air housing in small groups in a roofed, straw-bedded paddock with a group hutch were implemented in a prospective intervention study (1905 calves, 19 intervention and 19 control farms, over one year): antimicrobial use was five times lower in "outdoor veal" farms compared to control farms (p < 0.001), but it was crucial to ensure that antimicrobial treatment reduction was not associated with decreased animal welfare, i.e., that sick animals were not left untreated. Welfare was assessed monthly on the farms, and organs of 339 calves were examined after slaughter. Cough and nasal discharge were observed significantly (p ≤ 0.05) less often in intervention than in control farms, mortality (3.1% vs. 6.3%, p = 0.020) and lung lesion prevalence (26% vs. 46%, p < 0.001) were lower; no group difference was seen in abomasal lesion prevalence (65% vs. 72%). Thus, besides reduced antimicrobial use, calf health and welfare were improved in "outdoor veal calf" farms in comparison to traditional operations. Full article

The evaluation and assessment of the level of pain calves are experiencing is important, as the experience of pain (e.g., due to routine husbandry procedures) severely affects the welfare of calves. Studies about the recognition of pain in calves, and especially pain management during and after common procedures, such as castration, dehorning, and disbudding, have been published. This narrative review discusses and summarizes the existing literature about methods for pain assessment in calves. First, it deals with the definition of pain and the challenges associated with the recognition of pain in calves. Then it proceeds to outline the different options and methods for subjective and objective pain assessment in calves, as described in the literature. Research data show that there are several tools suitable for the assessment of pain in calves, at least for research purposes. Finally, it concludes that for research purposes, various variables for the assessment of pain in calves are used in combination. However, there is no variable which can be used solely for the exclusive assessment of pain in calves. Also, further research is needed to describe biomarkers or variables which are easily accessible in the field practice. Full article