Survey of management practices related to bovine respiratory disease in preweaned calves on California dairies

INVITED REVIEW: An evaluation of EFSA opinion on calf welfare from a nutritional and management perspective

In March, 2023, the European Food Safety Authority published a Scientific Opinion on Calf Welfare. This Opinion was prepared in response to a request from the European Commission to provide an independent view on the welfare of calves that reflected the most recent scientific knowledge. Data sources used to develop their recommendations included peer-reviewed studies, expert knowledge, and gray literature. The Opinion considered specific scenarios and welfare consequences of specific management practices, including feeding fiber to calves raised for white veal and amount of cow-calf contact. Their Opinion suggested that calves should be fed specific quantities of forage NDF during the rearing cycle. Regarding separation of calves, the Committee recommended that the calf should remain with the cow for a minimum of 24 h and then be housed with another calf. They further suggested that prolonged cow-calf contact should increasingly be implemented due to benefits to both cow and calf to minimize stress of separation. The objective of this review is to assess the veracity of these recommendations and the scientific data that underpins them. This review will present a literature to support the contention that, from a nutritional and management perspective, these recommendations may impair calf welfare by exposing calves to innutritious rations containing excess fiber and increasing their risk of morbidity and mortality due to poor colostrum intake and exposure to disease-causing pathogens. Alternative recommendations are made that may further the goal of calf welfare in the context of nutrition and housing.

Management Practices of Bovine Mastitis and Milk Quality on Egyptian Dairies

Milk production continues to be the main source of income for dairy producers, and mastitis continues to be the major health challenge for dairy cows worldwide. The objective of the current study was to describe the different management practices implemented in Egyptian dairies, which may influence mastitis and improve milk quality. An in-person survey was completed with herd managers and owners of 20 Egyptian dairies selected using a stratified random sample from four of Egypt's milk sheds. The questionnaire included 80 questions that inquired about herd demographics, mastitis status and control, milking practices, and management practices of the study dairies. Statistical analyses included descriptive statistics, multiple factor analysis (MFA), and hierarchical clustering to identify the important principal components and different dairy clusters. Of the surveyed herds, 69.50% had less than 500 lactating cows, with Holstein as the main cow breed. The reported average milk production on the study herds was 31.1 (SE ± 1.10) Kg/cow/day. Housing of lactating, dry, and close-up cows was in open lots. The majority of the dairies milked cows were three times per day (90.63%), the remaining milked cows four (5.00%) or a mix of four and three times per day. Furthermore, herringbone parlor design was the most common parlor design (66.79%) in the study dairies. The most common disinfectants used for both pre- and post-milking teat dip were iodine-based, 90.0% and 95.0%, respectively, while 52.16% of the dairies reported that their milkers wore gloves during milking. The reported mean annual percentage of mastitis was 52.3%, as a percent of the milking herd. The study dairies reported the inspection of udder health through either visual inspection (95.00%), udder hygiene score (86.88%), teat end score (71.88%), and/or using CMT (54.91%). Contagious mastitis pathogens were reported in 45.2% of the study herds. More than 50% of the study herds relied on importing pregnant cows or pregnant heifers as replacements. Multiple factor analysis identified 20 questions and represented 5 components of variability related to mastitis on dairies. The current survey of Egyptian dairies described the herd demographics and different management practices related to mastitis control and prevention. All the study dairies relied on the blanket intramammary antimicrobial drugs at dry off when current research elsewhere has identified selective dry cow therapy as an integral component of antimicrobial stewardship on dairies. Further research is required to identify the association between different management factors and the occurrence of mastitis.

Effect of dry cow therapy on antimicrobial resistance of mastitis pathogens post-calving

The aim of this study was to evaluate the effect of dry cow therapy (DCT) on the antimicrobial resistance (AMR) profile of mastitis pathogens post-calving. A repository of isolates based on a DCT trial was utilized for the current study. A stratified random survey sample of cows from the trial were identified within the strata of season, herd, and trial treatment resulting in 382 cows. All isolates from the 382 cows were selected for the current study, which identified 566 isolates from milk samples collected at dry off (S1), post-calving (S2), and at the first clinical mastitis event up to 150 days in milk (S3). The AMR profiles were determined using broth microdilution method. Less than 10% of the coagulase-negative Staphylococcus species (CNS) isolates (n = 421) were resistant to tetracycline, ceftiofur, penicillin/novobiocin or erythromycin, while higher proportions of resistance to sulfadimethoxine (72%) and penicillin (28%) were observed. All Staphylococcus aureus (S. aureus) isolates (n = 4) were susceptible to all tested AMD except sulfadimethoxine, to which all isolates were resistant. Similarly, all Streptococcus spp. (n = 37) were susceptible to penicillin, penicillin/novobiocin, and ampicillin while resistant to tetracycline (17%). All coliforms (n = 21) were susceptible to ceftiofur, but resistance was recorded for sulfadimethoxine (70%), cephalothin (56%), and tetracycline (43%). The increased resistance percent from S1 to S2 was observed in CNS isolates from AMD-treated cows, with the highest increase recorded for penicillin (12.2%). Parametric survival interval regression models were used to explore the association between antimicrobial drug (AMD) therapy at dry off and the AMR phenotype post-calving. The accelerated failure-time metric was adopted to minimum inhibitory concentration measurements to permit interpretation of model exponentiated coefficients. Models for cows with CNS isolated at both S1 and S2 showed increased resistance against cephalothin, oxacillin, and ceftiofur in cows that received DCT from the same drug class, or a class with a shared resistance mechanism. In contrast, resistance of CNS isolates to tetracycline were associated with any AMD therapy at dry off. Resistance of CNS isolates to Penicillin decreased in CNS isolates in cows that received any AMD therapy at dry off compared to those that didn't. The study provided evidence that dry-cow IMM AMD was associated with AMR post-calving.

Survey of Management Practices and Farmers’ Perceptions of Diseases on Organic Dairy Cattle Farms in California

Simple Summary

In 2019, California accounted for approximately 40% of organic products in the US, and dairy products and milk were the top organic commodity in the state. The objective of this study was to describe organic dairy cattle farmers’ management practices and perceptions of diseases in California. A questionnaire on farm history and demographics, animal diseases, parasite problems, housing and pasture management, and organic education, was mailed to 160 organic dairy farms, of which 36 responded. Respondents were more likely to report mastitis in cows, pinkeye in heifers, and digestive problems in calves, as issues affecting their stock “often” or “almost always” in the last 12 months. Although most farmers vaccinated their cattle against Bovine Viral Diarrhea and Escherichia coli mastitis, they still described that these diseases frequently impacted their animals. Over half of the farmers did not perceive gastrointestinal parasites or biting flies to be a problem and did not observe signs of lice and mites. According to the results, the management of disease in all age classes is a concern; options and efficacies of alternative therapeutic methods, as well as preventive measures for organic dairies need to be further explored.

Abstract

In 2019, California accounted for approximately 40% of organic products in the US, and dairy products and milk were the top organic commodity in the state. The objective of this study was to describe organic dairy cattle farmers’ management practices and perceptions of diseases in California. A survey inquiring about farm history and demographics, animal diseases, parasite problems, housing and pasture management, and organic education, was mailed to 160 organic dairy farms, of which 36 (22.5%) responded. Among respondents, the majority (83.9%) were located in Northern California; median farm size was 310 cows, and the dominant breed was Holstein (60.0%). Respondents were more likely to report mastitis in cows (45.2%), pinkeye in heifers (31.3%), and digestive problems in calves (47.0%), as issues affecting their stock “often” or “almost always” in the last 12 months. Although most farmers vaccinated their cattle against Bovine Viral Diarrhea (86.1%) and Escherichia coli mastitis (80.6%), they still described that these diseases frequently impacted their animals. Over half of the farmers did not perceive gastrointestinal parasites or biting flies to be a problem and did not observe signs of lice and mites. According to the results, the management of disease in all age classes is a concern; options and efficacies of alternative therapeutic methods, as well as preventive measures for organic dairies need to be further explored.

Effectiveness of Intramammary Antibiotics, Internal Teat Sealants, or Both at Dry-Off in Dairy Cows: Clinical Mastitis and Culling Outcomes

Intramammary antibiotic (AB) and internal teat sealants (TS) infusion at dry-off have been used to prevent intramammary infections (IMI) in dairy cows during the dry period and reduce the risk of mastitis during the dry period and subsequent lactation. A randomized clinal trial was completed on eight California dairy herds to estimate the effects of different dry cow therapies (AB, TS, AB + TS or None) on clinical mastitis and culling. A total of 1273 cows were randomized to one of the four treatment groups over summer and winter seasons. For each enrolled cow, microbiological testing was done on quarter milk samples collected from the first detection of clinical mastitis within the first 150 days in milk (DIM) in the subsequent lactation. Statistical analysis was done using generalized linear mixed models. There were no significant differences in the odds of clinical mastitis or culling between cows treated with AB, TS, or AB + TS compared to the controls. Dry cow therapy with AB and/or TS had no statistically significant effect on clinical mastitis and cow culling during the first 150 DIM.

Factors Associated with Antimicrobial Stewardship Practices on California Dairies: One Year Post Senate Bill 27

BACKGROUND

The current study is aimed at identifying the factors associated with antimicrobial drug (AMD) use and stewardship practices on conventional California (CA) dairies a year after CA Senate Bill 27.

METHODS

Responses from 113 out of 1282 dairies mailed a questionnaire in 2019 were analyzed to estimate the associations between management practices and six outcomes including producer familiarity with medically important antimicrobial drugs (MIADs), restricted use of MIADs previously available over the counter (OTC), use of alternatives to AMD, changes in on-farm management practices, changes in AMD costs, and animal health status in dairies.

RESULTS

Producers who reported having a veterinarian-client-patient relationship (VCPR) and tracking AMD withdrawal intervals had greater odds of being familiar with the MIADs. Producers who began or increased the use of preventive alternatives to AMD in 2019 had higher odds (OR = 3.23, p = 0.04) of decreased use of MIADs previously available OTC compared to those who did not. Changes in management practices to prevent disease outbreak and the use of diagnostics to guide treatment were associated with producer-reported improved animal health. In addition, our study identified record keeping (associated with familiarity with MIADs), use of alternatives to AMD (associated with management changes to prevent diseases and decreased AMD costs), and use of diagnostics in treatment decisions (associated with reported better animal health) as factors associated with AMD stewardship.

CONCLUSIONS

Our survey findings can be incorporated in outreach education materials to promote antimicrobial stewardship practices in dairies.

Use of Beef Semen on Dairy Farms: A Cross-Sectional Study on Attitudes of Farmer Toward Breeding Strategies

The use of beef semen on dairy cows has been increasing steadily since 2017. We aimed to describe dairy management practices toward the use of beef semen by surveying farmers in California, the largest US dairy producer. In January 2020, we mailed a printed version of the beef semen use survey to 1,017 dairy producers in California, who also had the option to answer the survey online. The questionnaire consisted of 33 questions that were categorized into three sections: general herd information (n = 10), beef semen management (n = 17), and sexed dairy semen management (n = 6). The response rate was 13.9% (n = 141). Regression models were used to evaluate the associations between the dairy-beef crossbred sale price, use of beef semen, and use of sexed dairy semen vs. herd characteristics. The mean ± SD herd size was 1,693 ± 1,311 milking cows. Most dairies (81%) reported using beef semen on dairy cows. Among respondents, 78% reported extra profit as the main advantage of using beef semen, followed by control of heifer inventory (69%), genetic improvement (37%), and other factors (8%). Most respondents (58%) started using beef semen in the past 3 years and 34% of the respondents were breeding more than 30% of all the eligible cows with beef semen. Angus semen was the most used (reported by 89% of the respondents), followed by Limousin (12%), Wagyu (10%), Charolais (7%), others (5%, Limflex, Stabilizer, and Hereford), and Simmental (4%). Reproductive performance was an important criterion to select cows to receive beef semen and 45% of the respondents reported starting breeding cows with beef semen from the third breeding, 18% on the fourth breeding, and 21% on the fifth or greater breedings. The region of California (a proxy for type of production system) contracts with a calf ranch and the herd breed explained 76.7% of the observed variation in the day-old dairy beef crossbred calf price. Survey results demonstrated the widespread use of beef semen in dairies and the main breeding strategies adopted by dairy farmers.

2019 Survey of Antimicrobial Drug Use and Stewardship Practices in Adult Cows on California Dairies: Post Senate Bill 27

Antimicrobial resistance (AMR) is a global issue for both human and animal health. Antimicrobial drug (AMD) use in animals can contribute to the emergence of AMR. In January 2018, California (CA) implemented legislation (Senate Bill 27; SB 27) requiring veterinary prescriptions for medically important AMD use in food animals. The objective of our survey was to characterize AMD use, health management, and AMD stewardship practices of adult cows on CA dairies since the implementation of SB 27. In 2019, we mailed a questionnaire to 1282 California dairies. We received a total of 131 (10.2%) survey responses from 19 counties in CA. Our results showed that 45.6% of respondents included a veterinarian in their decision on which injectable AMD to purchase. Additionally, 48.8% of dairy producers included a veterinarian in their decision on which AMDs were used to treat sick cows. The majority (96.8%) of dairy producers were aware that all uses of medically important AMDs require a prescription. Approximately 49% of respondents agreed or strongly agreed that AMD use in livestock does not cause problems in humans. The survey documents antimicrobial use and stewardship practices in CA's dairy industry and focus areas for future research and education.

2018 Survey of antimicrobial drug use and stewardship practices in adult cows on California dairies: post-Senate Bill 27

BACKGROUND

A survey of California (CA) dairies was performed in spring 2018 to characterize antimicrobial stewardship practices, antimicrobial drug (AMD) use, and health management of adult cows on CA dairies since the implementation of the Veterinary Feed Directive (VFD) and the CA Senate Bill 27 (SB 27). Effective January 1, 2017, the U.S. Food and Drug Administration (FDA) implemented regulatory changes requiring veterinary oversight for therapeutic uses of medically-important antimicrobial drugs (MIADs) administered in feed (VFD) and water (veterinary prescription). Similarly, effective January 1, 2018, the CA legislature enacted California Food and Agricultural Code (FAC) 14400-14408, formerly known as Senate Bill 27 (SB 27) requiring veterinary prescriptions for all other dosage forms of MIADs.

METHODS

The questionnaire consisted of 43 questions partitioned into three sections to assess herd information, management practices, and AMD use and perspectives. The questionnaire was mailed to 1,282 grade A licensed dairies in CA and 149 responses (11.6%) were collected from 19 counties across the three defined regions of CA: Northern CA (NCA), Northern San Joaquin Valley (NSJV), and Greater Southern CA (GSCA).

RESULTS

Most dairies reported treating all dry cows with intramammary AMD and/or teat sealant at the end of a lactation (87.2%). In 92.3% of dairies, producers relied on the veterinarian for information about AMD used to treat cows. Treatment duration for cows treated with AMD was based on the drug manufacturer's label and veterinarian's instructions in most dairies (98.6%). Most respondents to the survey confirmed having a valid veterinarian-client-patient-relationship (VCPR) for their dairies (91.7%), participated in animal welfare audit programs (81.8%) and dairy quality assurance programs (52.9%). Approximately 98.6% respondents were aware that all uses of MIADs in livestock required a veterinary feed directive (VFD) or prescription and are no longer sold over-the-counter (OTC) in CA since January 1, 2018. Multiple factor analysis (MFA) was performed and identified seven components composed of 21 variables (questions) that explained 99.7% of the total variance in the data. Hierarchical cluster analysis on the principal coordinates of the MFA based on conventional dairy survey responses identified two clusters characterized as large conventional dairies (median herd size: 1,265 cows) and mid-sized conventional dairies (median herd size: 715 cows) mostly in GSCA and NSJV. The organic dairies grouped into a single cluster of median herd size of 325 cows mostly in NCA.

CONCLUSIONS

The survey results contribute to the knowledge of AMD use and antimicrobial stewardship practices on CA dairies since the implementation of the SB 27 and VFD laws and provide useful information for future evaluation of resistance-related risk in adult cows.

2018 Survey of factors associated with antimicrobial drug use and stewardship practices in adult cows on conventional California dairies: immediate post-Senate Bill 27 impact

BACKGROUND

Antimicrobial drugs (AMD) are critical for the treatment, control, and prevention of diseases in humans and food-animals. Good AMD stewardship practices and judicious use of AMD are beneficial to the preservation of animal and human health from antimicrobial resistance threat. This study reports on changes in AMD use and stewardship practices on California (CA) dairies, following the implementation of CA Senate Bill 27 (SB 27; codified as Food and Agricultural Code, FAC 14400-14408; here onward referred to as SB 27), by modeling the associations between management practices on CA conventional dairies and seven outcome variables relating to AMD use and stewardship practices following SB 27.

METHODS

A survey questionnaire was mailed to 1,282 grade A licensed dairies in CA in spring of 2018. Responses from 132 conventional dairies from 16 counties were included for analyses. Multivariate logistic regression models were specified to explore the associations between survey factors and six outcome variables: producers' familiarity with the Food and Drug Administration's (FDA), Silver Spring, WA, USA medically important antimicrobial drugs (MIAD) term; change in over-the-counter (OTC) AMD use; initiation or increased use of alternatives to AMD; changes to prevent disease outbreaks; changes in AMD costs; and better animal health post SB 27. We employed machine learning classification models to determine which of the survey factors were the most important predictors of good-excellent AMD stewardship practices of CA conventional dairy producers.

RESULTS

Having a valid veterinary-client-patient-relationship, involving a veterinarian in training employees on treatment protocols and decisions on AMDs used to treat sick cows, tracking milk and/or meat withdrawal intervals for treated cows, and participating in dairy quality assurance programs were positively associated with producers' familiarity with MIADs. Use or increased use of alternatives to AMDs since 2018 was associated with decreased use of AMDs that were previously available OTC prior to SB 27. Important variables associated with good-excellent AMD stewardship knowledge by CA conventional dairy producers included having written or computerized animal health protocols, keeping a drug inventory log, awareness that use of MIADs required a prescription following implementation of SB 27, involving a veterinarian in AMD treatment duration determination, and using selective dry cow treatment.

CONCLUSIONS

Our study identified management factors associated with reported AMD use and antimicrobial stewardship practices on conventional dairies in CA within a year from implementation of SB 27. Producers will benefit from extension outreach efforts that incorporate the findings of this survey by further highlighting the significance of these management practices and encouraging those that are associated with judicious AMD use and stewardship practices on CA conventional dairies.

A survey of pre-weaning calf management in Norwegian dairy herds

The knowledge on dairy calves’ needs with regards to milk feeding and social housing is expanding but to be able to make improvements, knowledge is needed on how calves are managed at present in Norway. The aim of this study was to describe selected milk-feeding practices and social housing procedures for young (pre-weaning) dairy calves in Norwegian herds. A short questionnaire was distributed to a random sample of 912 dairy producers. For each herd, we asked how much milk was fed to 3 week old dairy calves, number of daily milk feedings, usage of milk replacer, number of weeks calves were housed in single pens, and whether calves at 3 weeks had free access to drinking water. In total, 508 herd managers responded to the questionnaire (56% response rate). Descriptive statistics showed that median milk allowance for 3 week old calves was seven (IQR 6–8) L milk/d, ranging from 2 to 15 L/day. Consequently, 311 (61%) herds reportedly fed less than the current industry recommendation in Norway (8 L milk/d to young calves). Automatic milk feeders were used by 30 herds (6%). In herds feeding milk manually (n = 471), half of the herds (50%) fed milk twice daily. Median number of daily milk feedings was 3 (31%) while 13% fed four times/day or more frequent (6%). Of the 226 producers (46%) who reported to use milk replacer, this milk type was used from the calf age of (median) 2 weeks. Of all herds, 82 (16%) did not provide their 3 week old calves with free access to drinking water. In the surveyed herds, calves were housed in single pens for (median) 2 weeks (IQR 2–3), while legislation allows single housing until the age of 8 weeks. In conclusion, the milk allowances reported in this survey are low compared to industry recommendations which again are low compared to voluntary intakes of young dairy calves. Free access to drinking water is important to calf welfare but was not granted to all dairy calves. Most calves were reportedly group housed at an early age, which indicates an improved awareness with regards to the importance of social housing.

Survey on Antimicrobial Drug Use Practices in California Preweaned Dairy Calves

The California (CA) dairy industry was surveyed in July 2017 to evaluate producers' knowledge and perceptions and antimicrobial drug (AMD) use in preweaned dairy calves following the implementation of the nationwide veterinary feed directive final rule (VFD) in January 2017 and prior to statewide implementation of CA Senate Bill (SB) 27 in January 2018. Together, these regulations require veterinary oversight for all uses of medically important antimicrobial drugs (MIADs) administered to livestock in CA. Survey questionnaire was mailed to 1,361 CA Grade A milk producing dairies and calf ranches across CA resulting in a 12% (169) response. Most respondents (83%) were aware of the VFD and SB 27 changes. Use of antibiotics was perceived as important (77%) in raising preweaned dairy calves and judicious use of antibiotics was ranked as the most important antimicrobial stewardship practice, amongst record keeping, observing withdrawal periods, having a valid Veterinarian-Client-Patient-Relationship (VCPR), and use of alternatives to antibiotics. Treating sick calves was the major indication for AMD use (90.5%); however, few producers reported use of antibiotics to control (12.7%) or prevent disease (11%). Neomycin sulfate, chlortetracycline, oxytetracycline and sulfamethazine were the most used AMD. The respondents reported a decreased use of AMD in milk (10%) and in solid feed (5%), and discontinuation of one or more AMDs used in milk (18.6%) or in solid feed (5%) post-VFD rule implementation in 2017. Most respondents reported keeping treatment records and the information recorded included date (82%), dose (44%) and route (15%) of AMD used. A few respondents reported they had initiated use of alternatives to AMDs, such as vitamins (32.6%), minerals (25.6%), herbal remedies (11.6%) and pathogen specific antibodies (7%), post-VFD. The limited changes noted in AMD use could be attributed to the short period between the implementation of the VFD and the time of the survey. Our study outcomes identified opportunities to improve AMD use practices, including record keeping and use of AMD alternatives, and provides a baseline for future evaluation of the impact of these regulatory changes, as well as guidance for the future recommendations on best practices to promote judicious AMD use.

Epidemiology of antimicrobial resistance (AMR) on California dairies: descriptive and cluster analyses of AMR phenotype of fecal commensal bacteria isolated from adult cows

Background

This study describes the occurrence of antimicrobial resistance (AMR) in commensal Escherichia coli and Enterococcus/Streptococcus spp. (ES) isolated from fecal samples of dairy cows and assesses the variation of AMR profiles across regions and seasons following the implementation of the Food and Agricultural Code (FAC) Sections 14400–14408 (formerly known as Senate Bill, SB 27) in California (CA).

Methods

The study was conducted on ten dairies distributed across CA’s three milk sheds: Northern California (NCA), Northern San Joaquin Valley (NSJV), and the Greater Southern California (GSCA). On each study dairy, individual fecal samples were collected from two cohorts of lactating dairy cows during the fall/winter 2018 and spring/summer 2019 seasons. Each cohort comprised of 12 cows per dairy. The fecal samples were collected at enrollment before calving (close-up stage) and then monthly thereafter for four consecutive time points up to 120 days in milk. A total of 2,171 E. coli and 2,158 ES isolates were tested for antimicrobial susceptibility using the broth microdilution method against a select panel of antimicrobials.

Results

The E. coli isolates showed high resistance to florfenicol (83.31% ± 0.80) and sulphadimethoxine (32.45%), while resistance to ampicillin (1.10% ± 0.21), ceftiofur (1.93% ± 0.29), danofloxacin (4.01% ± 0.42), enrofloxacin (3.31% ± 0.38), gentamicin (0.32% ± 0.12) and neomycin (1.61% ± 0.27) had low resistance proportions. The ES isolates were highly resistant to tildipirosin (50.18% ± 1.10), tilmicosin (48% ± 1.10), tiamulin (42%) and florfenicol (46% ± 1.10), but were minimally resistant to ampicillin (0.23%) and penicillin (0.20%). Multidrug resistance (MDR) (resistance to at least 1 drug in ≥3 antimicrobial classes) was observed in 14.14% of E. coli isolates and 39% of ES isolates. Escherichia coli isolates recovered during winter showed higher MDR prevalence compared to summer isolates (20.33% vs. 8.04%). A higher prevalence of MDR was observed in NSJV (17.29%) and GSCA (15.34%) compared with NCA (10.10%).

Conclusions

Our findings showed high rates of AMR to several drugs that are not labeled for use in lactating dairy cattle 20 months of age or older. Conversely, very low resistance was observed for drugs labeled for use in adult dairy cows, such as cephalosporins and penicillin. Overall, our findings identified important differences in AMR by antimicrobial class, region and season.

On-farm screw press and rotary drum treatment of dairy manure-associated antibiotic residues and resistance

An on-farm solid-liquid separator (SLS) and rotary drum composter (RD) manure treatment system was monitored for its impact on antibiotic residues and antibiotic resistance genes (ARGs). Administered antibiotics were tracked, and treatment system mass flows were quantified. Total amounts of antibiotic residues and ARGs were calculated from measured concentrations and mass flows. Only oxytetracycline (OTC) and sulfadimethoxine (SDM) were detected in the manure treatment system influent. No β-lactams were measured despite comprising ∼25% of the antibiotics administered. Nearly 80% of OTC and >90% of SDM partitioned into SLS liquid effluent (SL). The RD reduced the mass of OTC remaining in the SLS solid effluent (SS) significantly by 50%, whereas the mass of SDM appeared to increase after RD treatment. All four ARGs tested were detected in influent, with >70% of the sul1, bla_OXA-1 , and intI1 genes (normalized by the 16S ribosomal RNA gene) partitioning into the SL. In contrast, about eight times more normalized tetO gene copies partitioned into the SS than in the SL. All ARGs remaining in the SS were significantly reduced by the RD treatment, with a noteworthy 98% reduction in normalized tetO gene copies. This study provides insight into on-farm levels of antibiotic residues and ARGs in dairy manure, their partitioning during SLS treatment, and their fate after a high-temperature RD treatment reaching 72.2 ± 0.18 °C near the outlet. It also notes the importance of mass-flow standardization of data, and the need to work towards standardization of manure system sampling protocols for antibiotic residues and ARGs.

A novel risk assessment tool for bovine respiratory disease in preweaned dairy calves

Due to the increased morbidity and mortality of bovine respiratory disease (BRD) in dairy calves, as well as an increasing urgency for the judicious use of antimicrobials in farm animals, a comprehensive risk assessment tool for BRD in preweaned dairy calves has been designed based on a longitudinal and a cross-sectional study. As a multifactorial disease complex in which immune function stressors increase susceptibility to respiratory pathology, risk management programs for environmental and husbandry practices may be an effective approach for BRD control. Practices of known or suspected effect on BRD in preweaned calves have been explored in 2 large studies correlating management factors to BRD prevalence (BRD 100 study) and incidence (BRD 10K study) and forming the scores presented here. Priority was given to results from multivariable over univariable model estimates. However, when used, univariable model estimates were adjusted for confounders or stratified by effect modifiers if necessary. Regression coefficients were translated into scores, which are presented in a field-ready tool consisting of (1) a risk assessment questionnaire, which identifies the herd-specific risk factors and the risk scores associated with each; (2) the California BRD scoring system to estimate the BRD prevalence at the time of risk assessment for future comparison with the prevalence after interventions; and (3) the BRD control and prevention herd management plan, which can be used to plan and track the interventions identified. Scores for 100 dairies across California were used to benchmark a dairy's risk on a spectrum. With the help of the risk assessment tool, dairy producers, calf managers, and veterinarians may be able to adjust management factors that affect BRD risk on a farm and objectively monitor BRD prevalence before and after management interventions. As a result, the BRD risk assessment tool described here is the first comprehensive effort for herd-specific BRD control and prevention.

Components of a risk assessment tool for prevention and control of bovine respiratory disease in preweaned dairy calves

Bovine respiratory disease (BRD) is the leading natural cause of death in US beef and dairy cattle, causing the annual loss of more than 1 million animals and financial losses in excess of $700 million. The multiple etiologies of BRD and its complex web of risk factors necessitate a herd-specific intervention plan for its prevention and control on dairies. Hence, a risk assessment is an important tool that producers and veterinarians can utilize for a comprehensive assessment of the management and host factors that predispose calves to BRD. The current study identifies the steps taken to develop the first BRD risk assessment tool and its components, namely the BRD risk factor questionnaire, the BRD scoring system, and a herd-specific BRD control and prevention plan. The risk factor questionnaire was designed to inquire on aspects of calf-rearing including management practices that affect calf health generally, and BRD specifically. The risk scores associated with each risk factor investigated in the questionnaire were estimated based on data from two observational studies. Producers can also estimate the prevalence of BRD in their calf herds using a smart phone or tablet application that facilitates selection of a true random sample of calves for scoring using the California BRD scoring system. Based on the risk factors identified, producers and herd veterinarians can then decide the management changes needed to mitigate the calf herd's risk for BRD. A follow-up risk assessment after a duration of time sufficient for exposure of a new cohort of calves to the management changes introduced in response to the risk assessment is recommended to monitor the prevalence of BRD.

Effect of flooring on growth performance, behaviour, health and economics in Surti buffalo calves during winter

Surti buffalo calves (25) of an average 63.52±6.01 days age and 49.68±2.16 Kg weight were randomly divided into 5 homogeneous treatment group of floor types, viz. Concrete floor (CC), Kachcha soil floor without bedding (SOIL), Concrete floor with paddy straw bedding (CC+PS), Kachcha soil floor with paddy straw bedding (SOIL+PS) and Rubber mat bedding (RM) as per Latin Square Design (LSD) for 60 days. DM intake and body weight were recorded at fortnightly interval. The behavioural parameters of the calves were studied by four instantaneous observations for three days in a week. Faecal consistency scoring and eye scoring was recorded as per standard method. Average daily gain (ADG) was highest in SOIL+PS (424.00 g) and lowest in CC (294.80 g). The pooled concentrate, roughage, milk and total DMI was 0.93±0.04, 0.92±0.05, 0.22±0.01 and 2.07±0.07 kg/day, respectively. Highest concentrate intake was in CC group whereas lowest was in SOIL group. Roughage intake was higher in SOIL+PS and CC+PS in which paddy straw was used. Behavioural parameters like cross grooming, licking of floor, playfulness by running/fighting and smelling were statistically (P<0.05) significant amongst treatment group. Significantly higher numbers of calves were found in standing position in CC group as compared to other groups indicating altered comfort zone. The mean faecal consistency score was lower (P<0.05) in SOIL+PS, RM and CC+PS group than SOIL and CC group. However, mean eye score remained statistically non-significant amongst treatment. Thus, paddy straw bedding during winter proved to be most effective either on concrete or soil surface as it overall increases growth performance and welfare of calves.

Preweaning cost of bovine respiratory disease (BRD) and cost-benefit of implementation of preventative measures in calves on California dairies: The BRD 10K study

Bovine respiratory disease (BRD) is a multifactorial disease that is estimated to affect 22% of preweaned dairy calves in the United States and is a leading cause of preweaning mortality in dairy calves. Overall cost of calfhood BRD is reflected in both the immediate cost of treating the disease as well as lifetime decrease in production and increased likelihood of affected cattle leaving the herd before their second calving. The goal of this paper was to develop an estimate of the cost of BRD based on longitudinal treatment data from a study of BRD with a cohort of 11,470 preweaned dairy calves in California. Additionally, a cost-benefit analysis was performed for 2 different preventative measures for BRD, an increase of 0.47 L of milk per day for all calves or vaccination of all dams with a modified live BRD vaccine, using differing assumptions about birth rate and number of calves raised per year. Average short-term cost of BRD per affected calf was $42.15, including the use of anti-inflammatory medications in the treatment protocols across all management conditions. The cost of treating BRD in calves appears to have increased in recent years and is greater than costs presented in previous studies. A cost-benefit analysis examined different herd scenarios for a range of cumulative incidences of BRD from 3 to 25%. Increasing milk fed was financially beneficial in all scenarios above a 3% cumulative incidence of BRD. Use of a modified live vaccine in dams during pregnancy, examining only its value as a form of BRD prevention in the calves raised on the farm, was financially beneficial only if the cumulative incidence of BRD exceeded 10 to 15% depending on the herd size and whether the dairy farm was raising any bull calves. The cost-benefit analysis, under the conditions studied, suggests that producers with high rates of BRD may benefit financially from implementing preventative measures, whereas these preventative measures may not be cost effective to implement on dairy farms with very low cumulative incidences of BRD. The long-term costs of calfhood BRD on lifetime productivity were not factored into these calculations, and the reduction in disease may be associated with additional cost savings and an improvement in calf welfare and herd life.

Evaluation of four commercial tests for detecting ceftiofur in waste milk bulk tank samples

The objective of this study was to identify factors affecting the accuracy of four commercial tests for ceftiofur drug residue in milk samples from bulk tank waste milk (WM). WM samples were collected from 12 California dairy farms which were initially tested using liquid chromatography (LC-MS/MS) to confirm their negative status for drug residues above the FDA established tolerance/safe levels. The milk samples were also tested for fat, protein, lactose, solids non-fat (SNF), somatic cell count (SCC), coliform count, and standard plate count (SPC). Each WM sample was divided into two aliquots, one labeled as negative for drug residues (WMN) and the second spiked with ceftiofur as positive for ceftiofur residues (WMPos). Both types of WM samples were tested to evaluate the performance of 4 commercially available tests: Penzyme® Milk Test, SNAP® β-lactam, BetaStar® Plus and Delvo SP-NT®. Three assays in triplicates for the WMN and WMPos were conducted for each WM sample. Test were evaluated using sensitivity, specificity, positive predictive value, negative predictive value and positive likelihood ratio. Kruskal-Wallis method was used to evaluate the effect of milk quality parameters on true positive (TP) and false negative (FN) test results. All WMPos samples were identified as positive by all four tests, rendering 100% sensitivity for each test. The specificity for Penzyme, BetaStar, Delvo, and SNAP tests were 59.2, 55.5, 44.4, and 29.6, respectively. Overall, all tests correctly identified samples with ceftiofur residues (WMPos), as shown by 100% sensitivity. Greater variability was observed regarding identification of samples free of any drug residue, with Penzyme and BetaStar having the highest risk for correctly identifying TN samples. Our findings indicate that when selecting commercial tests to detect drug residues in WM, milk quality parameters must be considered if the aim is to reduce FP test results.

Management factors associated with bovine respiratory disease in preweaned calves on California dairies: The BRD 100 study

The objective of this cross-sectional study was to determine how management practices on California dairies may be associated with bovine respiratory disease (BRD) in preweaned calves. A convenience sample of 100 dairies throughout California, providing a study population of 4,636 calves, were visited between May 2014 and April 2016. During each farm visit, in-person interviews with the herd manager or calf caretaker were conducted to collect information about herd demographics, maternity pen, colostrum and calf management, herd vaccinations, and dust abatement. A random sample of preweaned calves was identified and evaluated for the presence of BRD using a standardized tool. A survey-adjusted generalized linear mixed model with a logit link function was fitted with calf as the unit of analysis and dairy as the random effect. Mean study herd size (±SE) was 1,718 (±189.9) cows. Survey-adjusted estimates of breed types in the sample were 81.6% (±0.6) Holstein, 13.1% (±0.4) Jersey, and 5.3% (±0.5) crossbred or other purebred breeds, and calf sex proportions were 73.8% (±1.0) female and 26.2% (±1.0) male. Overall survey-adjusted BRD prevalence in the study herds was 6.91% (±0.69). Housing factors positively associated with BRD were metal hutches compared with wood hutches [odds ratio (OR) = 11.19; 95% confidence interval (CI) = 2.80–44.78], calf-to-calf contact in calves >75 d of age (OR = 9.95, 95% CI = 1.50–65.86), feeding Holstein calves <2.84 L of milk or replacer per day (OR = 7.16, 95% CI = 1.23–41.68), and lagoon water used for flushing manure under hutches compared with no flush (OR = 12.06, 95% CI = 1.93–75.47). Providing extra shade over hutches (OR = 0.08; 95% CI = 0.02–0.37), feeding calves at least 90% saleable milk (OR = 0.27, 95% CI = 0.13–0.54) or pasteurized milk (OR = 0.10; 95% CI = 0.03–0.36), and feeding >5.68 L of milk or replacer per day to Jersey calves (OR = 0.04; 95% CI = 0.01–0.28) were negatively associated with BRD. Our study identified management practices on California dairies with variability and that may contribute to differences in BRD prevalence, which will be incorporated into a risk-assessment tool to control and prevent BRD in preweaned dairy calves.

Epidemiology of bovine respiratory disease (BRD) in preweaned calves on California dairies: The BRD 10K study

Bovine respiratory disease (BRD) is one of the leading causes of death in dairy heifers. The objective of this prospective cohort study was to characterize the epidemiology of BRD in preweaned dairy calves and to identify management practices associated with decreased risk of BRD. Dairies were chosen for the study based on management practices, location, size, and willingness to participate. A total of 6 dairies, ranging in size from 700 to 3,200 milking cows, in 6 counties across California's Central Valley, were enrolled in the study for at least 1 year. A total of 11,945 calves were born on the study dairies and followed until weaning. Incidence of BRD was estimated using treatment records. Trained study personnel performed comprehensive calf management surveys and estimated BRD prevalence on every dairy at least once every season. A shared frailty model was used to model the associations between management practices and BRD hazard. The final models included data from complete records of 11,470 calves. The overall BRD study period prevalence across the study herds was 22.8%. The mean BRD incidence density rate on all the study dairies was 0.17 BRD cases [95% confidence interval (CI) = 0.16-1.74] per calf-month at risk. The shared frailty model identified that feeding only waste or saleable milk (compared with use of milk replacer), feeding over 3.8 L of milk per day to calves under 21 d of age, frequent changing of maternity pen bedding, and administration of modified live or killed BRD vaccines to dams before calving significantly reduced the risk of BRD. Risk factors for BRD included housing calves in wooden hutches with metal roofs, compared with all-wood hutches, twin births, and perception of dust occurring "regularly," as reported by calf managers, compared with a perception of "no dust" in the calf-raising area. All 4 seasons were analyzed, and both summer (hazard ratio = 1.15; 95% CI = 1.01 to 1.32) and spring (hazard ratio = 1.26; 95% CI = 1.11 to 1.44) were associated with a higher risk of BRD compared with winter. The current longitudinal study identified specific housing and feeding practices that could be modified to decrease risk of BRD. In addition, season was observed to have a strong effect on calves' risk of developing BRD on California dairies.

Needs assessment for cooperative extension dairy programs in California

The present study aimed to identify dairy producer needs and how best to direct and deliver cooperative extension (CE) programming. In March 2017, we mailed a needs assessment survey to grade A dairy producers in California (n = 1,080). The response rate was 15.4% (n = 166) and herd size averaged 1,405 milking cows (range 83-5,500). The geographic distribution of survey responses was representative of the distribution of dairies throughout the state. Producers were asked to indicate the level of concern for a predetermined list of 11 issues. Rank of concern had 3 numeric levels: (1) very concerned, (2) somewhat concerned, or (3) not concerned. Mean and percentage of responses in each rank for each issue topic were calculated. The top 5 concerns/obstacles indicated were (1) milk price, (2) labor availability/quality, (3) environmental issues/regulations, (4) labor costs, and (5) water quality/availability. Surveyed respondents were also asked to determine the level of priority of a predetermined list of 13 CE research and educational opportunities. Producers ranked topics as low, medium, or high priority. The 5 highest priority research topics were (1) herd health, (2) environmental issues, (3) reproduction, (4) milk quality, and (5) water quality. The 5 highest priority educational topics were (1) herd health, (2) milk quality, (3) reproduction, (4) environmental issues, and (5) calf and heifer management. Producers were then asked to identify the target audience for CE information delivery and preferred information delivery method. Most respondents indicated that the target audience should be dairy owners (93%) or managers (66%). Fewer producers indicated a target audience of dairy employees (27%) or allied industry (23%). Preferable information delivery methods were newsletter or magazine articles (81%), half-day/short meetings (47%), and on-farm training/meetings (39%). Webinars and 2- or 3-d destination meetings were the least preferable methods (27 and 9%, respectively). Survey results will serve to develop future dairy cooperative extension programs in California.

Space allowance influences individually housed Holstein male calves' age at feed consumption, standing behaviors, and measures of immune resilience before and after step-down weaning

Many dairy calves in the southwestern regions of the United States are raised in wooden hutches with 1.23 m² of free space that house 3 calves individually. Producers claim that calves in hutch systems are not ready to wean and be placed in groups at the country-average age of 6 wk. Calves may remain in this individual housing system until as late as 10 wk of age. The objective of this study was to modify space allowance of hutches and evaluate weaning readiness using age at solid feed consumption, standing behaviors, and measures of immunity. Calves were randomly assigned at 4 d of age to conventional (CONV; 1.23 m² of space; n = 18), moderate (MOD; 1.85 m² of space; n = 17), or maximized (MAX; 3.71 m² of space; n = 19) space allowance in hutches. These modifications also changed the number of calves housed per hutch from 3 (CONV) to 2 (MOD) and 1 (MAX). Calves were fed milk replacer via bottle twice daily until weaning and offered ad libitum feed throughout the experiment. Step-down weaning was initiated (Wi) at age 53 or 54 d by withdrawal of the p.m. bottle and was completed (Wc) 11 d later by removal of the a.m. milk replacer. Accelerometer data for standing behaviors were collected relative to Wi (3 consecutive days to represent -4 wk, -3 d, 3 d, and 3 and 5 wk). Blood samples were collected in the a.m. just before Wi (d 0) and at d 3, 11, 14, and 18 after Wi. Calves provided with more space (MOD and MAX) compared with CONV calves consumed feed at an earlier age and had slightly healthier erythrocytes, greater circulating glucose, and fewer circulating eosinophils. The CONV calves had haptoglobin (Hp) responses to the stressors of both Wi and Wc and had more IFN-γ from whole blood stimulated with phytohemagglutinin-P. The MAX calves had the least active neutrophils (phagocytosis and oxidative burst), but MOD calves' leukocytes secreted the most TNF-α from whole blood stimulated with lipopolysaccharide. Just before and after weaning, MAX calves spent more time per day in the standing position than CONV and MOD calves and had an Hp response to Wc, but MOD calves did not have an Hp response to Wi or Wc. Based on these results, MOD calves were the most ready for weaning; therefore, they potentially can be moved to group housing at an earlier age than CONV calves, thus improving animal welfare concerns over space allowance and individual housing.

Regional management practices and prevalence of bovine respiratory disease in California's preweaned dairy calves

The objective of this cross-sectional study was to estimate the prevalence of bovine respiratory disease (BRD) in California preweaned dairy calves and identify management practices that are associated with BRD. A convenience sample of 100 dairies in the 3 distinct dairy regions of California was surveyed. Regions evaluated were Northern California (NCA), northern San Joaquin Valley (NSJV), and greater Southern California (GSCA). A questionnaire on calf management practices and demographic information was administered via in-person interviews at each dairy and a random sample of preweaned calves was evaluated using the California BRD scoring system on the same day. Prevalence of BRD varied between the 3 dairy regions: 9.30% in NCA, 4.51% in NSJV, and 7.35% in GSCA. Breed was not associated with BRD prevalence at the statewide level, but differences in prevalence were observed between breeds across the regions with a higher prevalence in NCA for Jerseys and in GSCA for Holsteins, compared with NSJV. Prevalence of BRD was not different between organic and conventional dairies. Colostrum management practices, including heat treatment and feeding colostrum from multiparous cows, varied by region and were associated with lower BRD prevalence. Calves housed in group pens, a practice observed primarily in NCA, had a higher BRD prevalence than those in individual housing. Feeding salable milk was also more common in NCA and was associated with lower BRD prevalence. Ground and road surfaces adjacent to the calf raising area were also variable by region, and paved surfaces were associated with lower BRD prevalence. Management practices associated with BRD varied across the state and may be addressed to inform the adoption and implementation of potentially protective management decisions on California dairies and other regions with similar dairy systems.

Space allowance influences individually housed Holstein bull calf innate immune measures and standing behaviors after castration at 3 weeks of age

Dairy calves in the Southwest regions of the United States are typically raised individually in wooden hutches with 1.23 m² of space. The objective of the study was to determine if increased space allowance in wooden hutches influences measures of innate immunity and behaviors of Holstein bull calves pre- and postcastration. Calves were randomly assigned at 4 d of age to conventional (CONV; 1.23 m² of space; n = 18), moderate (MOD; 1.85 m² space; n = 17), or maximized space allowance (MAX; 3.71 m² space; n = 19) in hutches. Calves were surgically castrated at 24 d of age. Peripheral whole blood samples were collected at -1, +1, +5, and +12 d of castration. Accelerometer loggers (n = 16 calves per treatment) were used from -3 to +5 d of castration to assess standing behaviors. All calves decreased total standing duration the day of castration versus precastration. Overall, MAX spent the most time in the stand position postcastration versus CONV and MOD. Within treatments, MOD and MAX had increased plasma cortisol 1 d postcastration versus precastration. A treatment × time tendency was observed for cortisol at 12 d postcastration; MAX had the least circulating cortisol. A treatment × time tendency for circulating haptoglobin (Hp) was observed and Hp was greatest among CONV 1 d pre- and 12 d postcastration. Compared with precastration, CONV had increased Hp at 1, 5, and 12 d, whereas MOD had increased Hp at 5 d, and Hp remained similar within MAX. A treatment × time tendency for tumor necrosis factor-α (TNF-α) from lipopolysaccharide-stimulated whole blood was observed; at 1 d postcastration, MOD had the most TNF-α, whereas MAX had the least. Within MAX, calves had increased TNF-α from precastration to 5 d postcastration. A treatment × time interaction was observed for whole blood bactericidal activity against Escherichia coli (WB anti-E). The CONV tended to have the greatest WB anti-E at d -1, but at d 1 and 5 postcastration, CONV had the least WB anti-E. Overall, MAX had less intensity of neutrophil oxidative burst versus CONV and MOD. The lower response of neutrophil oxidative burst and slower Hp secretion after castration is indicative that the wound site likely had less microbial exposure. The findings of this study suggest that calves housed with more space are potentially at less risk of too much inflammation after castration, which may likely be due to the effects of increased space on hide cleanliness and increased standing time.

Wooden hutch space allowance influences male Holstein calf health, performance, daily lying time, and respiratory immunity

Dairy calves in the western United States are commonly raised individually in wooden hutches with a space allowance of 1.23m(2)/calf. Recent legislative initiatives in California and across the United States were passed regarding concern over space allowance for farm animals. The objective of this study was to determine if rearing male Holstein calves in wooden hutches modified to increase space allowance would influence measures of performance, lying time per day, health, and respiratory immunocompetence. At 4d of age, 60 calves were randomly assigned to 1 of 3housing treatments: (1) conventional housing (CONV; 1.23m(2)/calf), (2) 1.5 × CONV (MOD; 1.85m(2)/calf), or (3) 3 × CONV (MAX; 3.71m(2)/calf). Intakes of milk and solid feed were recorded daily and body weight was measured at 0, 3, 6, 10, and 12 wk of age. For the first 3 wk of the trial, calves were scored daily for fecal consistency, hydration, and hide cleanliness. In addition, calves were scored for respiratory health (i.e., nasal and eye discharge, ear position) until 7 wk of age. The total lying duration per day was recorded using data loggers at 3, 6, and 10 wk of age. Eight clinically healthy calves from each treatment were sensitized with subcutaneous ovalbumin (OVA) and then challenged with aerosolized OVA to assess calf respiratory immunity at 11 wk of age. Bronchoalveolar lavage fluid (BALF) was collected 4d after the OVA challenge and analyzed for leukocyte differentials and OVA-specific IgG, IgG1, IgA, and IgE. Calf average daily gain and body weight were positively associated with space allowance at approximately 3 wk before weaning and throughout postweaning, respectively. A greater space allowance decreased lying time after 46d. Space allowance did not influence fecal consistency, but there was a tendency for MAX calves to take 1d longer to recover from loose feces than MOD calves. The MAX calves had the fewest (%) observations with feces on their body compared with CONV or MOD. At 3 wk of age, peripheral eosinophil concentrations decreased with increased space allowance. However, observations (%) of eye discharge increased with greater space allowance. Among calves challenged with OVA, MOD calves had the least BALF OVA-IgE, and the percent of BALF eosinophils decreased with increased space allowance. Increased space allowance for calves raised in wooden hutches may improve some measures of calf performance, health, and respiratory immunocompetence.

Stress, immunity, and the management of calves

Despite many advances in management and housing of dairy calves, 1 in 10 US dairy heifers die before weaning. A better understanding of the internal and external stimuli that contribute to the physiological and behavioral responses of calves to stressors is needed to reduce the risk of morbidity and mortality. Feeding calves their first meal is crucial, as successful passive transfer reduces the risk of mortality and morbidity. Sexually dimorphic immune and stress responses appear to be present in young cattle, but more research is needed to determine if this is caused by human bias for female calves. After that first feeding, 1 in 10 heifers and most bull calves in the United States are transported to specialized calf-raising facilities, yet information is lacking on the newborn calf stress response during transit. Whether calves are raised on site or at a calf ranch, individual housing systems are commonly used in the United States to reduce the risk of pathogen exposure and provide individual feeding and healthcare. However, health, growth, and social implications may be present for calves in alternative systems with greater space allowance than conventional systems or group housing. Disbudding and castration are typically performed at an early age for dairy calves during the pre-wean stage. These stressors often take place when the calf has decreased passive transfer of Ig and immunity is developing. Availability of pain mitigation through anesthetics and analgesics is limited, but evidence indicates that analgesics attenuate suppressed leukocyte function during these procedures. Solid-feed intake is a primary measure for determining weaning readiness, but some milk replacer formulas may influence the calf's oral behaviors before weaning; therefore, alternate weaning methods may need to coincide with alternate milk replacer formulas. The calf's behavioral and stress response at weaning may influence its immunity during the transition from individual to group housing (commingling). Alternate commingling strategies and nutritional supplements may help with this transition, but more research is needed to explore feasible alternatives. Optimizing the calf's health and well-being at these early stages may improve its long-term health and welfare.