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Breed structures of Australian dairy herds over time were described for a large subset of milk‐recording herds. The focus for this study was to describe the use of crossbreeding by dairy farmers, specifically proportions of herds using crossbreeding, whether they were using two‐breed or three‐breed crossbreeding systems, and how herd‐breed structures changed over time. The most common breed structure in Australian milk‐recording herds between 2000 and 2013 was two‐breed crossbreeding (39% of herd‐years). The next most common breed structure was purebred (35%). Over the period studied, the proportion of herds that were purebred decreased, while the proportion of herds that were crossbreeding increased (particularly three‐breed crossbreeding herds). Herd‐breed structures and changes over time varied with region and with the herd's calving system. There were also considerable changes in breed structure within herds, including herds changing breed structure before reverting back to their original breed structure. These results indicate that breed structures in milk‐recording dairy herds in Australia are dynamic, and that farmers have commonly employed crossbreeding strategies. [ABSTRACT FROM AUTHOR]

Objective: To compare fixed‐time artificial insemination (FTAI) conception rates and serum progesterone concentrations at the time of FTAI for cows treated with the original Ovsynch program (OV) with those treated with a modified Ovsynch (MO) program. Design This was a randomised clinical trial. Methods: The study used five split‐calving, pasture‐based dairy herds in Southwest Victoria, Australia. Controls (n = 851) received the OV program: day 0 gonadotropin‐releasing hormone, day 7 prostaglandin F2α (PGF), day 9 gonadotropin‐releasing hormone and FTAI at day 10. The treatment group (n = 852) received a MO program with an additional prostaglandin injection on day 8. Subsets of cows from each group were sampled for blood progesterone at the time of FTAI. Results: The treatment group demonstrated FTAI conception rates that were 7% (95% confidence interval 2%–12%) greater than the control group. After adjusting for the effect of age, days in milk at Mating Start Date and herd, the odds of conception using FTAI was 1.36 (95% confidence interval 1.12–1.66) times greater for treatment group cows compared with control group cows. The variability of serum progesterone concentrations at the time of FTAI was significantly less for treatment group cows compared with control group cows. Conclusion: For Holstein‐Friesian and Holstein‐Friesian cross‐bred cows managed in pasture‐based dairy herds in southern Australia, a MO protocol, including a second injection of prostaglandin F2α on day 8, increased FTAI conception rates compared with cows receiving the OV protocol. [ABSTRACT FROM AUTHOR]

This study aimed to determine the prevalence of antimicrobial resistance (AMR) in commensal E. coli from healthy lactating cows and calves in the Mediterranean pasture-based feeding dairy system of Western Australia (WA). Fecal samples were collected from healthy adult lactating cows and healthy calves from dairy farms in WA. Presumptive commensal E. coli was isolated from these samples and confirmed using matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Broth microdilution was used to assess the prevalence and the phenotypic AMR profiles of the E. coli isolates to 8 antimicrobial agents of dairy industry and human importance. The minimum inhibitory concentration (MIC) for each isolate was interpreted using the Epidemiologic Cutoff (ECOFF) and Clinical and Laboratory Standards Institute (CLSI) breakpoints. Genomic characterization provided multi-locus sequence types and AMR genes for a selection of isolates categorised as non-wild type (NWT) by ECOFF values for the combination of ampicillin, trimethoprim-sulfamethoxazole, and tetracycline. From a total of 1,117 fecal samples (633 adult, 484 calf) collected across 26 randomly selected farms, 891 commensal E. coli isolates were recovered (541 adult, 350 calf). Commensal E. coli classified as NWT was highest for ampicillin for both adult (68.8%; 95% CI = 64.7 - 72.7) and calf feces (67.1%; 95% CI = 62.0 - 72.0). A large proportion of tetracycline NWT and trimethoprim-sulfamethoxazole NWT organisms were also identified from calf feces, being 44.0% (95% CI = 38.7 - 49.4) and 24.6% (95% CI = 20.2 - 29.4) respectively. Clinical resistance prevalence was low, being higher for calves than for adult feces (ampicillin (adult: 7.8% (95% CI = 5.7 - 10.3); calf: 30.0% (95% CI = 25.2 - 35.1), tetracycline (adult: 6.3% (95% CI = 4.4 - 8.7); calf: 40.3% (95% CI = 35.1 - 45.6), and trimethoprim-sulfamethoxazole (adult: 2.6% (95% CI = 1.4 - 4.3); calf: 22.0% (95% CI = 17.7 - 26.7)). Commensal E. coli originating from calf feces was significantly higher in NWT prevalence compared with adult feces for ciprofloxacin (P = 0.023), gentamicin (P = 0.02), tetracycline (P < 0.001), and trimethoprim-sulfamethoxazole (P < 0.001). The overall number of antimicrobials an isolate was classified as NWT toward varied among farms and was significantly higher for isolates originating from calf than adult feces (P < 0.001). The strain type and sampling source of the commensal E. coli investigated were both associated with the commonality of the resultant resistance genome. Clinical resistance and NWT classification were highest for ampicillin, tetracycline, and trimethoprim-sulfamethoxazole, all antimicrobials commonly used in the treatment of dairy cattle in Australia. Though highly variable across farms, commensal E. coli isolated from healthy dairy calf feces had significantly higher NWT and multidrug resistance (MDR) prevalence compared with feces from healthy adult lactating dairy cows. The resistant genome identified in MDR isolates, though not always consistent with the phenotype, included QnrS1 and genes encoding AmpC β-lactamase and aminoglycoside phosphotransferase., (© 2024, The Authors. Published by Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Introduction: Quantification of antimicrobial resistance (AMR) is beneficial to inform policies and direct prudent antimicrobial use., Aim: This study aimed to assess the current published evidence of AMR from passive and active ad hoc surveillance activities within the Australian dairy cattle industry., Methods: Following a scoping review framework 373 articles published before January 2023 were retrieved using the keyword search function from two online databases (PubMed® and Web of Science™ Core Collection). The duplicate articles were removed and the title, abstract, and full text of the remaining articles were reviewed following the study objectives and inclusion criteria (location, subject/theme, and data). Data from the remaining articles were extracted, summarised, interpreted and the study quality assessed using the Grades of Recommendations, Assessment, Development, and Evaluation guidelines., Results: A total of 29 articles dating from the 1960 s until 2022 were identified to meet the study criteria (passive: n = 15; active: n = 14). Study characteristics such as sampling type, sampling method, and AMR assessment were all common characteristics from both passive and active surveillance articles, being milk samples, individual sampling, and phenotypic assessment respectively. Passive surveillance articles had a wider range in both the type of bacteria and the number of antimicrobials investigated, while active surveillance articles included a higher number of bacterial isolates and sampling from healthy populations. There was an overall low level of clinical AMR across all articles. Higher prevalence of non-wildtype Escherichia coli, Salmonella spp., and Staphylococcus spp., although limited in data, was suggested for commonly used Australian veterinary antimicrobials for these bacteria. The prevalence of phenotypic AMR varied due to the health and age status of the sampled animals. The articles reviewed in this study suggest the prevalence of AMR genes was higher for commonly used antimicrobials, although genes were not always related to the phenotypic AMR profile., Conclusions: Published evidence of AMR in the Australian dairy cattle industry is limited as demonstrated by only 29 articles included in this review following selection criteria screening. However, collectively these articles provide insight on industry AMR prevalence. For example, the suggestion of non-wildtype bacteria within the Australian dairy cattle indicating a risk of emerging or increasing industry AMR. Therefore, further surveillance is required to monitor the development of future AMR risk within the industry. Additionally, evidence suggesting that animals varying in health and age differ in prevalence of AMR imply a requirement for further research into animal population demographics to reduce potential bias in data collated in both national and global surveillance activities., Competing Interests: Declaration of Competing Interest, (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

We conducted a retrospective cohort study to validate the efficacy of the Australian multitrait fertility estimated breeding value (EBV). We did this by determining its associations with phenotypic measures of reproductive performance (i.e., submission rate, first service conception rate, and early calving). Our secondary aim was to report the associations between these reproductive outcomes and management and climate-related factors hypothesized to affect fertility. Our study population included 38 pasture-based dairy herds from the northern Victorian irrigation region in Australia. We collected records for 86,974 cows with 219,156 lactations and 438,578 mating events from the date on which managers started herd recording until December 2016, comprising both fertility-related data such as insemination records, calving dates, and pregnancy test results, and systems-related data such as production, herd size, and calving pattern. We also collected hourly data from 2004 to 2017 from the closest available weather station to account for climate-related factors (i.e., temperature humidity index; THI). Multilevel Cox proportional hazard models were used to analyze time-to-event outcomes (days to first service, days to cow calving following the planned herd calving start date), and multilevel logistic regression models for binomial outcomes (conception to first service) in the Holstein-Friesian and Jersey breeds. A 1-unit increase in daughter fertility EBV was associated with a 5.4 and 8.2% increase in the daily hazard of calving in the Holstein-Friesian and Jersey breeds respectively. These are relative increases (i.e., a Holstein-Friesian herd with a 60% 6-wk in-calf rate would see an improvement to 63.2% with a 1-unit increase in herd fertility EBV). Similar results were obtained for submission and conception rate. Associations between 120-d milk yield and reproductive outcome were complicated by interactions with 120-d protein percentage and calving age, depending on the breed and outcome. In general, we found that the reproductive performance of high milk-yielding animals deteriorated faster with age than low milk-yielding animals, and high protein percentage exacerbated the differences between low and high milk-yielding animals. Climate-related factors were also associated with fertility, with a 1-unit increase in maximum THI decreasing first service conception rate by 1.2% for Holstein-Friesians but having no statistically significant association in the Jersey breed. However, THI had a negative association in both breeds on the daily hazard of calving. Our study validates the efficacy of the daughter fertility EBV for improving herd reproductive performance and identifies significant associations between 120-d milk and protein yields and THI on the fertility of Australian dairy cows., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)

Aims: The aims of this study were to determine antimicrobial prescription patterns and the factors affecting antimicrobial selection amongst Australian dairy veterinarians., Methods: A structured questionnaire was administered to Australian dairy cattle veterinarians using the Qualtrics online survey platform. Questions focused on their (1) demographics; (2) opinions surrounding antimicrobial use, resistance, and stewardship; (3) decision-making drivers of both prescription and selection of commonly prescribed antimicrobials; (4) awareness on the guidelines for antimicrobial usage and sources of information concerning antimicrobials., Key Results: A total of 135 responses (14.1% response rate) from all eight dairying regions in Australia were received. The attitudes, perceptions, and concerns of dairy veterinarians towards antimicrobials indicated a high agreement regarding label indications (96%), consequences of off-label prescription (95%), and the presence of an antimicrobial resistance (AMR) risk (73%), when prescribing antibiotics. A four-dimensional categorical principal components analysis (CATPCA) model indicated most of the variation in opinion was due to AMR risk, trade-offs, prescription concerns and active substance concerns. The first active substance most dairy veterinarians chose for a scenario involving mastitis and dry cow therapy (DCT) treatment was cloxacillin. Decision-making drivers for antimicrobial choice when providing advice regarding the supply of antimicrobials for mastitis and DCT treatment were predominately clinical factors; however, diagnostics were rarely used in determining antimicrobial choice due to cost of implementation, diagnostic accuracy (sensitivity, specificity), and benefit issues. Non-clinical decision-making drivers included the perception of practicality for Australian Veterinary Association (AVA) prescription guidelines, opinions surrounding AMR risk and prescription concerns, consideration of Expert Advisory Group on Antimicrobial Resistance (EAGAR) scores, number of years worked with dairy farms, and the number of dairy farms they regularly consult for. When available at the practice, prescription policies were considered to impact on animal welfare outcomes and on the probability of AMR emergence. The major information sources influencing decision making on antimicrobial prescription for the Australian dairy veterinarians were clinical experience (93%) and product labels (81%)., Conclusions: Australian dairy veterinarians are generally aware of the risk of resistance to antimicrobials and the need for stewardship, with clinical factors having the most impact on antimicrobial prescription. However, non-clinical factors incorporating awareness of guidelines and their attitudes on antimicrobial resistance risk and prescription concerns impact on the choice and prescription of antimicrobials., Implications: The development of prescription policy and guidelines, alongside effective communicative extension programs to increase veterinarian uptake, provides an avenue to mitigate AMR risk in Australian dairy cattle., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Reproductive performance in dairy cattle has declined over the last 50 years as an unintended consequence of selection for high milk yield. Since the early 2000s, dairy geneticists have released successive versions of fertility estimated breeding values (EBV) to assist in reversing this trend. At the herd level, fertility EBV can help managers accelerate improvements in reproductive performance by acting as a second selection criteria when used in tandem with a breeding index. However, use of the fertility EBV in sire selection currently varies between herd managers. The aim of this study was to better understand the reasons why herd managers choose or do not choose to select high-fertility EBV sires, using the Theory of Planned Behavior (TPB) as a social research framework. Thirty-five Victorian dairy herd managers were recruited as part of a larger study investigating the daughter fertility Australian Breeding Value and interviewed using a series of questions examining TPB constructs. The interviews were recorded and transcribed using template analysis. A wide range of herd manager types were enrolled into the study, with representation from diverse systems. Out of the 35 herd managers, 27 included fertility in their list of high-priority breeding objectives. A wide variation in results was consistent with previous studies that have demonstrated marked heterogeneity in herd manager attitudes toward bull selection. Herd manager-perceived barriers to selection of sires with high daughter fertility EBV included a lack of high daughter fertility bulls with other desirable traits, a lack of trust in the fertility EBV or in the Australian EBV system, difficulty in interpreting international proofs, information overload, semen prices, low bull reliability, and difficulty in understanding bull catalogs. Not all herd managers found the process problematic, however, particularly if a breeding consultant was employed to select all or most of the sires. Herd manager-perceived barriers for choosing to select daughter fertility as a breeding objective include a lack of awareness of the EBV, a lack of interest in genetics in general, low confidence in the impact of genetic selection for fertility, and a feeling that fertility was not important for their production system. The results of this study suggest that animal geneticists and on-farm service providers need to work together to allow the opportunities arising from appropriate use of fertility EBV to be realized more broadly across the dairy industry., (Copyright © 2021 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Objective: To compare fixed-time artificial insemination (FTAI) conception rates and serum progesterone concentrations at the time of FTAI for cows treated with the original Ovsynch program (OV) with those treated with a modified Ovsynch (MO) program., Design: This was a randomised clinical trial., Methods: The study used five split-calving, pasture-based dairy herds in Southwest Victoria, Australia. Controls (n = 851) received the OV program: day 0 gonadotropin-releasing hormone, day 7 prostaglandin F 2α (PGF), day 9 gonadotropin-releasing hormone and FTAI at day 10. The treatment group (n = 852) received a MO program with an additional prostaglandin injection on day 8. Subsets of cows from each group were sampled for blood progesterone at the time of FTAI., Results: The treatment group demonstrated FTAI conception rates that were 7% (95% confidence interval 2%-12%) greater than the control group. After adjusting for the effect of age, days in milk at Mating Start Date and herd, the odds of conception using FTAI was 1.36 (95% confidence interval 1.12-1.66) times greater for treatment group cows compared with control group cows. The variability of serum progesterone concentrations at the time of FTAI was significantly less for treatment group cows compared with control group cows., Conclusion: For Holstein-Friesian and Holstein-Friesian cross-bred cows managed in pasture-based dairy herds in southern Australia, a MO protocol, including a second injection of prostaglandin F 2α on day 8, increased FTAI conception rates compared with cows receiving the OV protocol., (© 2020 Australian Veterinary Association.)

Animal welfare assessments were conducted on 50 Australian pasture-based dairy farms of varying herd sizes: 16 small (<300 cows), 15 medium-sized (300-500 cows), 11 large (501-750 cows), and 10 very large (751+ cows). A protocol based on elements of Welfare Quality adapted for Australian conditions was developed to assess the broad categories of good feeding, housing, health, and appropriate behavior. Farm records, body condition scores, integument injuries, fecal plaques, avoidance distance of humans, and fecal pat scoring for acidosis assessment were undertaken. The mean maximum kilograms of grain fed per day significantly increased with herd size, from 5.2 ± 0.38 (small), 7.7 ± 0.29 (medium-sized), 8.8 ± 0.45 (large), to 10.1 ± 0.80 kg (very large). Acidosis was not related to herd size based on either farm records or fecal pat scoring. All cows had access to water for more than 12 h in a 24-h period. More larger farms had water points on the farm tracks or at the dairy. Very large farms (90%) were more likely than others (36-39%) to provide water suitable for human consumption. Integument lesions were not related to herd size and were uncommon; 56 and 84% of farms had no cows with lesions or hairless areas, respectively, and no farm had >6% integument lesions. Heat stress is an important welfare risk in Australia. All farms had some form of cooling strategy; shade in all paddocks was more common on smaller farms (>90%) than others (<75%). Sprinklers were more common on large or very large farms (>80%) than others (<65%). Mastitis and lameness were the most common health conditions, followed by dystocia, downer cows, and gastrointestinal diseases. Prevalence of lameness, mastitis, downer cows, dystocia, and gastrointestinal disease were not related to farm size. Larger farms were more likely to have electronic infrastructure to monitor or electronically draft cows for inspection. We found wide variation in the avoidance distance of humans, but this was not related to farm size. Larger farms had longer walking distances to pasture and longer time away from pasture, which could affect the time available for behaviors such as lying down. Animal welfare risks differ on Australian farms compared with housed cattle. As animal welfare is multidimensional, both animal- and resource-based indicators can be useful. Animal-based indicators have strengths in that, when measured accurately, they genuinely reflect the outcome being measured, but they also have weaknesses in that the point-estimate of a disease prevalence on a given day may not be representative of other times of year or differences in case definition may exist when farm records are used. Similarly, resource-based indicators have strengths in that they may be applicable to longer periods, but weaknesses because the fact a resource is present does not guarantee it is being used. Identifying the major risks to animal welfare on individual farms and ensuring a plan is in place to effectively manage them should be an important element of any on-farm animal welfare assessment protocol., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

On Australian pasture-based farms, where cows may often walk several kilometers and stand for several hours per day in a crowded concrete yard while they wait to be milked, the potential for lameness to negatively affect animal welfare is of ongoing concern. Several studies have shown that farmers tend to underestimate the incidence of lameness. Further, improving farmer diagnosis/identification of lameness is likely to result in more prompt treatment, which in turn will improve clinical and animal welfare outcomes. We scored 19,154 cows over 50 farms for lameness, in herd groups ranging from approximately 100 to 1,000 cows, as they left the milking parlor. We compared these results with farmer-diagnosed lameness records on the same day. We used a scoring system of 0, walks normally; 1, walks unevenly; 2, lame; and 3, very lame. All very lame cows had been detected by the farmer, but overall, farmers detected only 24% of cows identified by lameness scoring. An analysis of the position of lame cows within the milking order showed that lameness scoring of the entire herd was necessary to detect all the lame cows as only 60% of lame cows appeared in the last 30% of cows to be milked. However, lameness scoring only the last 200 cows to be milked could be used as a screening test to identify herds with a lameness prevalence below a given threshold., (Copyright © 2019 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

In large Australian pasture-based dairy herds, it is common for the time taken to milk a herd of cows to be up to 4 h. Cows are collected from the paddock as a group, wait in turn in the dairy yard to be milked, and then return individually to the paddock or feed pad immediately after leaving the milking parlor. In such herds, we previously found a consistent milking order, resulting in some cows being regularly away from pasture for several hours per day more than others. Increased time away from pasture may affect the time budgets of cows because of decreased opportunity for grazing or lying down. Lying behavior is a high-priority behavior for cows, and the duration of lying has been used as an important measure of their welfare. We applied activity monitors for 7 d to 15 cows toward the beginning and 15 cows toward the end of the milking order in 10 dairy herds milking 500 to 730 cows as a single group to understand the effect of extra time spent in the dairy on lying behavior. Study cows typically produced 6,000 to 8,000 L in a 300-d lactation on rotary dairy platforms with 40 to 80 units, being fed 2.5 to 6 kg of grain mix in the milking parlor daily, with the rest of the diet being supplied as pasture or forage provided in the pasture or close to the exit of the dairy. Over the 10 farms, 1,948 cow-days were available for analysis. The furthest paddocks on each farm were 1.8 to 3.5 km walking distance from the dairy. A wide range of steps were taken each day, ranging from 1,705 to 15,075 (mean = 5,916). The main predictor of the number of steps was the farm on which the cows were located. Cows that spent less than an hour waiting to be milked (and would be unlikely to have their ability to lie down affected by the milking process) laid down for a mean of 9.8 h/d. Steps walked and delay in the dairy waiting to be milked were both significantly associated with lying time, but the effect was not large. A regression model accounting for the waiting time at the dairy, steps taken, cow age, and farm was used to investigate the relationship with daily lying time. For every 1,000 steps, lying time reduced by 0.49 h; however, the number of steps explained only 1% of the variation in lying time. For every hour increase in waiting time at the dairy, lying decreased by approximately 14 min, but this explained only 14% of the variation in lying. We concluded that milking time durations of 2 to 4 h, common in large Australian pasture-based dairy herds, did not significantly affect the time budget for lying of individual cows in our study herds. Whereas the effect of long milking times does not appear to be a major risk to animal welfare in terms of lying time, the effect on cow health and production warrants further investigation., (Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Mycoplasma bovis has been increasingly recognised worldwide as an economically important pathogen of cattle, causing a range of diseases, including pneumonia, mastitis, polyarthritis and otitis media. It is believed that M. bovis utilises a range of cell surface proteins, including nucleases, to evade the host immune response and survive. However, despite the importance of neutrophils in controlling pathogenic bacteria, the interaction between these cells and M. bovis is not well-characterised. In addition to phagocytosis, neutrophils combat pathogens through the release of neutrophil extracellular traps (NETs), which are composed of their nuclear and granular components, including DNA. Here we investigated the effect of the major membrane nuclease MnuA of M. bovis, which in vitro is responsible for the majority of the nuclease activity of M. bovis, on NET formation. We quantified NET formation by bovine neutrophils 4 h after stimulation with wild-type M. bovis, an mnuA mutant and a mnuA-pIRR45 complemented mnuA mutant. NETs were detected following stimulation of neutrophils with the mnuA mutant but not after exposure to either the wild-type or the mnuA-pIRR45 complemented mutant, and NETs were degraded in the presence of even low concentrations of wild type M. bovis. Surprisingly, there was no increase in levels of intracellular reactive oxygen species (ROS) production in neutrophils stimulated with M. bovis, even though these neutrophils produced NETs. These results clearly demonstrate that M. bovis can induce NET formation in bovine neutrophils, but that the major membrane nuclease MnuA is able to rapidly degrade NETs, and thus is likely to play a significant role in virulence. In addition, M. bovis appears to induce NETs even though ROS production seems to be suppressed., (Copyright © 2018. Published by Elsevier B.V.)

We used on-farm records from dairy infrastructure to examine the consistency of the milking order over 150 d in 5 Australian dairy herds that were milking more than 500 cows as a single group. Within a single day the difference in milking order rank position was less than 20 percentage points for 72% of cows. The correlation coefficient comparing milking rank position in the morning and afternoon was 0.72, with the position of cows at the beginning and end of the milking order being more consistent than cows toward the middle of the milking order. Over a period of 150 d, cows with a mean position in the first and last 20% of the milking order maintained their position more consistently than cows in the middle of the milking order. Milking position of cows between one month and the next was highly correlated (r = 0.88). In large herds, subpopulations of cows are regularly milked toward the beginning and the end of the milking order. It is common for cows to be collected from the paddock as a group, to wait as a group in the dairy yard to be milked, and to return individually to the paddock or feed pad immediately after they have been milked. Thus, cows milked later in the milking order are likely to be away from the paddock for several hours longer than cows milked earlier in the milking order. This may affect their welfare though differences in time available for lying down, equality of pasture eaten, and time spent standing in the dairy yard., (Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

In the pasture-based, seasonally calving dairy herds of southern Australia, the mating period usually consists of an initial artificial insemination period followed by a period of natural service using herd bulls. Bull breeding soundness evaluations (BBSE) were performed on 256 bulls from 32 dairy herds in southwest Victoria, using guidelines produced by the Australian Cattle Veterinarians, before and immediately after a single natural mating period. At the same time, herd managers were questioned regarding the management of the bulls. The objectives of this study were to describe the management practices of dairy herd bulls; to describe the causes of increased risk of reduced fertility in dairy herd bulls, as measured by a standard BBSE; and to describe the reasons for bull removal by herd managers during mating. At the premating BBSE, 19.5% of bulls were classified as high risk of reduced fertility, mostly due to physical abnormalities and reduced semen quality. At the postmating BBSE, 36.5% of bulls were classified as high risk of reduced fertility, mostly due to physical abnormalities, primarily lameness. Of the bulls used, 15.9% were removed from normal mating use by the herd manager, predominantly due to lameness and injuries. A premating BBSE is recommended in dairy herd bulls to identify bulls at risk of reduced fertility. Lameness is the most common problem in dairy herd bulls during the natural mating period, and risk factors associated with lameness in these bulls should be identified to better manage herd bulls., (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

In pasture-based, seasonally calving dairy herds of southern Australia, the mating period usually consists of an initial artificial insemination period followed by a period of natural service using herd bulls. The primary objective of this study was to identify associations between individual bull- and herd-level management factors and bull fertility as measured by a pre- and postmating bull breeding soundness evaluation (BBSE). Multivariable mixed effects logistic regression models were used to identify factors associated with bulls being classified as high risk of reduced fertility at the premating and postmating BBSE. Bulls older than 4 yr of age at the premating BBSE were more likely to be classified high risk compared with bulls less than 4 yr of age. Bulls that were in herds in which concentrates were fed before mating were more likely to be classified as high risk at the postmating BBSE compared with bulls that were in herds where concentrates were not fed. Univariable analyses also identified areas in need of further research, including breed differences between dairy bulls, leg conformation and joint abnormalities, preventative hoof blocking for bulls, and mating ratios., (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

One of the major challenges for dairy producers is to produce, harvest, and store high-quality colostrum and feed it to their replacement heifer calves. Limited published data are available in Australia regarding the relationship between colostrum management, hygiene, and quality. The objectives of this study were to investigate (1) the colostrum storage and handling practices carried out on farm; (2) the immunoglobulin concentration and bacterial composition of colostrum being fed to replacement dairy heifer calves; (3) the percentage of colostrum being fed to replacement dairy heifer calves that meet industry recommendations; and (4) risk factors for bacterial contamination of colostrum. The study was carried out on 24 dairy farms located near Rochester, Victoria, Australia. Two hundred forty colostrum samples were collected (10 samples per farm). Each farm harvested and stored first-milking colostrum under normal farm conditions. A 10-mL sample of the colostrum was collected in a sterile container immediately before feeding, and a Brix refractometer reading was taken. The samples were then frozen at -4°C and submitted for bacterial concentration analysis. Fifty-eight percent of colostrum samples met the recommended industry standard of a total plate count (TPC) of <100,000cfu/mL, and 94% of colostrum samples met the recommended industry standard of total coliform count (TCC) of 10,000cfu/mL. However, when all the current industry recommendations for TPC, TCC, and Brix refractometer percentage for colostrum quality were considered, only 23% of the samples met all standards. These findings demonstrate that a large number of calves were at risk of receiving colostrum of poor quality, with high bacterial loads that may have interfered with the acquisition of transfer of passive immunity and affected calf health. Further investigation is required to identify the farm-specific factors that may influence the level of bacterial contamination of colostrum. Recommendations as a result of this study include refrigeration of excess colostrum shortly (within 1h) after collection and thorough disinfection of the calf feeding apparatus before use., (Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Although large herds (more than 500 cows) only represent 13% of Australian dairy farms, they represent more than 35% of the cows milked. A survey of Australian dairy farmers was conducted to assess relationships between herd size and known or proposed risk factors for adverse animal welfare outcomes in Australian dairy herds in relation to increasing scale of production. Responses from 863 Australian dairy farms (13% of Australian dairy farms) were received. Increasing herd size was associated with increases in stocking density, stock per labor unit, and grain fed per day-all of which could reasonably be hypothesized to increase the risk of adverse welfare outcomes unless carefully managed. However, increasing herd size was also associated with an increased likelihood of staff with formal and industry-based training qualifications. Herd size was not associated with reported increases in mastitis or lameness treatments. Some disease conditions, such as milk fever, gut problems, and down cows, were reported less in larger herds. Larger herds were more likely to have routine veterinary herd health visits, separate milking of the main herd and the sick herd, transition diets before calving, and written protocols for disease treatment. They were more likely to use monitoring systems such as electronic identification in the dairy, computerized records, daily milk yield or cell count monitoring, and pedometers or activity meters. Euthanasia methods were consistent between herds of varying sizes, and it was noted that less than 3% of farms make use of captive-bolt devices despite their effectiveness and ready availability. Increasing herd size was related to increased herd milking time, increased time away from the paddock, and increased distance walked. If the milking order of cows is consistent, this may result in reduced feed access for late-milking-order cows because of a difference in time away from the paddock. More than 95% of farmers believed that their cows were content most of the time, and cows were reported as well behaved on more than 90% of farms. Although the potential animal welfare issues appear to be different between herd sizes, no evidence existed for a relationship between herd size and adverse welfare outcomes in terms of reported disease or cow contentment levels., (Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Background: Oriental theileriosis is a tick-borne, protozoan disease of cattle caused by members of the Theileria orientalis-complex. Recent outbreaks of this disease in eastern Australia have caused major concerns to the dairy and beef farming communities, but there are no published studies of the economic impact of this disease. On a farm in Victoria, Australia, we assessed whether oriental theileriosis has an impact on milk production and reproductive performance in dairy cows., Methods: Blood samples collected from all 662 cows on the farm were tested using an established molecular test. For individual cows, milk production and reproductive performance data were collected. A clinical assessment of individual cows was performed. Based on clinical findings and molecular test results, the following groups of cows were classified: group 1, with cardinal clinical signs of oriental theileriosis and molecular test-positive for T. orientalis; group 2, with mild or suspected signs of theileriosis and test-positive; group 3, with no clinical signs and test-positive; and group 4, with no clinical signs and test-negative. Milk production and reproductive performance data for groups 1, 2 and 3 were each compared with those for group 4 using linear and logistic regression analyses, respectively., Results: At 100 days of lactation, group 1 cows produced significantly less milk (288 l; P = 0.001), milk fat (16.8 kg; P < 0.001) and milk protein (12.6 kg; P < 0.001) compared with group 4. At this lactation point, group 2 also produced significantly less milk fat (13.6 kg; P = 0.002) and milk protein (8.6 kg; P = 0.005) than group 4. At 305 days of lactation, group 1 cows produced significantly less milk (624 l; P = 0.004), milk fat (42.9 kg; P < 0.001) and milk protein (26.0 kg; P < 0.001) compared with group 4 cows. Group 2 cows also produced significantly less milk fat (21.2 kg; P = 0.033) at this lactation point. No statistically significant difference in reproductive performance was found upon pairwise comparisons of groups 1-3 with group 4 cows., Conclusions: The present findings demonstrate that clinical oriental theileriosis can cause significant milk production losses in dairy cattle.

Automated walk-over weighing systems can be used to monitor liveweights of cattle. Minimal literature exists to describe agreement between automated and static scales, and no known studies describe repeatability when used for daily measurements of dairy cows. This study establishes the repeatability of an automated walk-over cattle-weighing system, and agreement with static electronic scales, when used in a commercial dairy herd to weigh lactating cows. Forty-six lactating dairy cows from a seasonal calving, pasture-based dairy herd in southwest Victoria, Australia, were weighed once using a set of static scales and repeatedly using an automated walk-over weighing system at the exit of a rotary dairy. Substantial agreement was observed between the automated and static scales when assessed using Lin's concordance correlation coefficient. Weights measured by the automated walkover scales were within 5% of those measured by the static scales in 96% of weighings. Bland and Altman's 95% limits of agreement were -23.3 to 43.6 kg, a range of 66.9 kg. The 95% repeatability coefficient for automated weighings was 46.3 kg. Removal of a single outlier from the data set increased Lin's concordance coefficient, narrowed Bland and Altman's 95% limits of agreement to a range of 32.5 kg, and reduced the 95% repeatability coefficient to 18.7 kg. Cow misbehavior during walk-over weighing accounted for many of the larger weight discrepancies. The automated walk-over weighing system showed substantial agreement with the static scales when assessed using Lin's concordance correlation coefficient. This contrasted with limited agreement when assessed using Bland and Altman's method, largely due to poor repeatability. This suggests the automated weighing system is inadequate for detecting small liveweight differences in individual cows based on comparisons of single weights. Misbehaviors and other factors can result in the recording of spurious values on walk-over scales. Excluding outlier weights and comparing means of 7 consecutive daily weights may improve agreement sufficiently to allow meaningful assessment of small short-term changes in automated weights in individuals and groups of cows., (Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Questionnaires were posted to 800 randomly selected registered Victorian dairy farmers in 1996. Five hundred and thirty-four responses were received and analysed. Johne's disease (JD) had been diagnosed on the farm of 13.2% of respondents in the last 5 years. JD was rated second only to neonatal diarrhoea in importance as a disease of calves, even though other diseases occurred more frequently. However, there was a low level of compliance with JD control recommendations by the respondents. There was no significant difference in the number of JD control recommendations adopted by farmers between the three major Victorian regions. There was a significant difference in compliance between farms having had a diagnosed case of JD and those that had not. Although there is awareness among dairy farmers of the importance of JD, there appears to be a poor implementation of measures by farmers to prevent the spread of the disease. Current JD control recommendations and the method of information transfer to Victorian dairy farms should be reassessed to ensure that dairy heifers are reared with minimal risk of transmission of JD.

Background: Renal cell carcinoma is a potentially fatal tumor that occasionally presents during pregnancy. Based on our experience with three patients and a review of the recent cases in the literature, we believe there has been a change in presentation of this lesion over that described in previous reviews., Cases: Two of three women with renal cell carcinoma found during pregnancy had symptoms suggesting recurrent urinary tract infection. The renal tumors were all discovered by ultrasound. In addition, magnetic resonance imaging was used for preoperative, intragestational staging of one patient., Conclusion: Renal cell carcinoma should be considered in women of childbearing age who present with recurrent or refractory urinary tract symptoms, flank pain, or a palpable flank mass. Ultrasound appears to be the imaging procedure of choice for evaluating the urinary system in pregnant women.