The objective was to evaluate the effect of housing type on health and performance of preweaned dairy calves. One hundred calves, Holsteins (HO) or Holstein-Jersey crosses (HJ), were randomly assigned to a Calf-Tel (L. T. Hampel Corp., Germantown, WI) polyethylene hutch exposed to direct sun light (n=25 for both HO and HJ) or a wire hutch with a plywood shade located under trees (n=24 and 26 for HO and HJ, respectively). Calf rectal temperature, respiratory rate, health scores, and weaning weight were compared by housing type. Rectal temperatures were higher in calves in Calf-Tel hutches compared with calves in wire hutches at 1500 h, at 40.1±0.28 and 39.1±0.22°C, respectively. Similarly, respiratory rates were higher in calves in Calf-Tel hutches compared with calves in wire hutches at 1500 h, at 90±15 and 65±10 breaths per minute, respectively. Frequencies of calves presenting abnormal ear scores did not differ between calves in Calf-Tel or wire hutches. Abnormal eye scores were less likely to occur for calves in the wire hutches. Frequencies of calves with signs of respiratory disease, such as nasal discharge and coughing, were higher in the wire hutches compared with the Calf-Tel hutches. No differences were noted in the incidence and time of first diarrhea event in calves between hutch types. Calves in wire hutches had 5.47 greater odds of receiving veterinary treatment compared with calves in the Calf-Tel hutches. Weaning weights were not different for calves in Calf-Tel or in wire hutches. The lower frequency of calves with abnormal health scores and receiving veterinary treatment in Calf-Tel hutches and the lack of difference in weight gain suggests that this housing system adapted well to the specific environmental conditions of this study.

Mastitis is one of the most prevalent and costly diseases in dairy cattle. Key components for adequate mastitis control are the detection of early stages of infection, as well as the selection of appropriate management interventions and therapies based on the causal pathogens associated with the infection. The objective was to characterize the pattern of electrical conductivity (EC) in milk during intramammary infection, considering specific mastitis-causing pathogen groups involvement. Cows (n = 200) identified by an in-line mastitis detection system with a positive deviation ≥15% in the manufacturer’s proprietary algorithm for EC (high electrical conductivity (HEC)) were considered cases and enrolled in the study at the subsequent milking. One control (CON) cow, within normal ranges for EC, was matched to each case. A composite milk sample was collected aseptically from each cow for bacteriological culture. Milk yield (MY) and EC were recorded for each milking during ±7 days relative to enrollment. Milk cultures were categorized into gram positive (GP), gram negative (GN), other (OTH) and no growth (NOG). Data were submitted for repeated-measures analysis with EC as the dependent variable and EC status at day −1, bacteriological culture category, parity number, stage of lactation and days relative to sampling as main independent variables. Average (± standard error (SE)) EC was greater in HEC than in CON cows (12.5 ± 0.5 v. 10.8 ± 0.5 mS/cm) on the day of identification (day −1). Milk yield on day −1 was greater in CON than in HEC (37.6 ± 5.1 v. 33.5 ± 5.2 kg). For practical management purposes, average EC on day −1 was similar for the different bacteriological culture categories: 11.4 ± 0.6, 11.7 ± 0.5, 12.3 ± 0.8 and 11.7 ± 0.5 mS/cm in GN, GP, OTH and NOG, respectively. Parity number was only associated with day −1 EC in HEC group, with the greatest EC values in parity 3 (12.3 ± 0.3 mS/cm), followed by parity 2 (11.9 ± 0.2 mS/cm), parity >3 (11.6 ± 0.5 mS/cm) and primiparous cows (11.2 ± 0.2 mS/cm). An effect on EC for the interaction of day relative to identification by pathogen gram category was observed. The same interaction effect was observed on daily MY. Overall, the level of variation for MY and EC between- and within-cows was substantial, and as indicated by the model diagnostic procedures, the magnitude of the variance in the cows in the CON group resulted in deviations from normality in the residuals. We concluded that characteristic temporal patterns in EC and MY in particular pathogen groups may provide indications for differentiation of groups of mastitis-causing pathogens. Further research to build detection models including EC, MY and cow-level factors is required for accurate differentiation.

The use of milk leukocyte differential (MLD) test has been proposed as a complement to somatic cell count (SCC) to assess the presence and the severity of intramammary infection. However, detailed information regarding the behavior of MLD under different physiological or pathological stages of the cow is nonexistent. The objective was to analyze the association between milk leukocyte proportions provided by a commercial automated MLD test and multiple cow and quarter-level variables. The study population consisted of 104 Holstein cows (32 primiparous and 72 multiparous) in one farm. Cows were categorized by days in milk as early (<50 DIM; n=29), middle (50–250 DIM; n=25), and late lactation (>250 DIM; n = 50). Milk from 416 quarters was collected and analyzed for lymphocytes (LYM), neutrophils (NEU), and macrophages (MAC) counts using an automated milk fluorescence microscopy system. Concurrently, a sterile composite milk sample was collected from each cow for pathogen identification through microbiological culture. Culture results were classified as no growth (NOG), gram-negative (GN), gram-positive (GP), or other (OTH). Milk leukocyte proportions varied depending on the level of total leukocyte counts (TLC; P < 0.001). Similarly, leukocyte ratios (NEU:LYM, NEU:MAC, and phagocyte:LYM) were different for multiple TLC categories (P < 0.05). There was no association between parity number and MLD; however, cows in early lactation had the greatest proportions of NEU and LYM. Leukocyte ratios varied depending on parity number and stage of lactation. Cows in the medium milk-yield category had the smallest proportions of NEU and LYM, and there was significant variation in leukocyte ratios, depending on the level of milk yield. In healthy quarters, MLD were not associated with quarter position; however, the NEU:MAC ratio was greater in rear quarters than in front quarters. In quarters with TLC >100,000, NEU% was greater in rear quarters than in front quarters (P = 0.03). For quarters with pathogen growth, TLC was greatest for GN followed by OTH and GP (P < 0.001). Milk LD depended on the isolated pathogen group, although the magnitudes of the differences were small. Although the changes in the proportions of leukocytes in milk were associated with categories of TLC, levels of milk yield, and mastitis-causing pathogen groups, the deviations were small in magnitude. Additional research is necessary to determine the potential applications for this methodology.

Ketosis is a common metabolic disease in fresh dairy cows. Clinical and subclinical ketosis (SCK) can cause reduced milk yield, decreased milk protein, reduced reproductive capacity, and increased risk of displaced abomasum. Usually, diagnosing ketosis is performed by measuring acetoacetate or BHBA levels in the blood, urine, or milk samples. Measuring BHBA in serum or plasma is considered the gold standard diagnostic test for subclinical ketosis, because this method has stability, but the price for ketone strips is approximately $0.08/strip while the price for the electronic BHBA measuring system is approximately $1.00. UF/IFAS researchers conducted a study to compare the two, using 72 Holstein cows between 14–40 days in milk from three dairy farms in north-central Florida with 450–800 lactating dairy cows. The key finding for this experiment is that no difference exists in BHBA concentration between cows that had a trace or small in the ketone strip reading. This 3-page fact sheet was written by Klibs N. Galvão, Achilles Vieira Neto, Gustavo Peña, Joao Bittar, and Lucas Ibarbia, and published by the UF Department of Veterinary Medicine-Large Animal Clinical Sciences, October 2012. VM186/VM186: Comparing the Urine Ketone Strip Test and the Handheld Ketone Meter to Diagnose Ketosis in Early Lactation Dairy Cows (ufl.edu)

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