Staphylococci and mammaliicocci: which species are important for udder health on organic dairy farms?

Variation in species distribution and diversity of staphylococci and mammaliicocci (SaM) causing intramammary infections in dairy cattle is associated with different management practices. Disparate selective pressures on organic dairies could potentially result in population differences of these mastitis-causing bacteria. The species-specific effect on quarter somatic cell count of SaM for a population of certified organic dairies has not been described previously. The current study presents data from a longitudinal study of 10 certified organic dairy farms. The objective was to estimate how quarter milk somatic cell count (qmSCC) varied as a result of infection with the most frequently isolated SaM species. Aerobic culture of quarter milk samples to identify IMI was conducted in parallel with determination of qmSCC. A linear hierarchical repeated measures mixed model was used to estimate qmSCC for quarters with an IMI caused by a given SaM species, compared with culture-negative quarters. The model included days in milk at time of sampling to adjust qmSCC estimates for each SaM species. The final data set consisted of 648 quarters with an IMI due to 10 different SaM spp. and 1,972 culture-negative quarters. S. chromogenes was the most frequent species, followed by S. aureus, S. haemolyticus, and S. simulans. A large amount of variability was observed in the somatic cell score for culture-negative quarters and those infected with many SaM spp., especially S. chromogenes, S. haemolyticus, S. simulans, and S. aureus. Somatic cell score was significantly higher in quarters infected with S. agnetis, S. aureus, S. chromogenes, S. devriesei, S. haemolyticus, S. hyicus, S. simulans, S. warneri, and S. xylosus compared with culture-negative quarters. The highest cell count was for quarters infected with S. warneri, followed by S. aureus, S. agnetis, and S. hyicus. The relative distribution of various SaM species and their effect on qmSCC in this population of small to midsize organic farms was similar to previous studies. Although the increase in qmSCC was modest for most SaM species observed, the widespread prevalence of these intramammary pathogens could potentially contribute to sizeable increases in bulk tank SCC.

Effect of Age at First Calving on the Reproduction Parameters, Metabolic Profile, and Fatty Acid Composition of Polish Holstein Friesian (PHF) and Crossbreds PHF × Swedish Red (SRB) Cattle

BACKGROUND

The high dairy production of Polish Holstein Friesian (PHF) cows determines high energy requirements in the early stages of lactation. Unfortunately, it is very often difficult to meet this demand through feedstuffs; therefore, homeostasis may be disturbed and metabolic diseases may occur, causing a majority of cows' health problems. Breeders are, therefore, looking for alternatives to the PHF breed using crossbreeding.

METHODS

This experiment involved 30 PHF cows and 30 PHF × Swedish Red (SRB) crossbred hybrid cows, divided into two age groups, <2 years and >2 years, at first calving. Milk and blood samples were collected at 35 ± 5 days postpartum for analysis. Data on reproductive performance were also analyzed.

RESULTS

This study revealed lower milk production for the crossbreds hybrid (27.44 kg compared to 32.08 kg), with a higher basic composition content than PHF cows (fat: 3.97% compared to 3.83%, protein: 3.53% compared to 3.27%). The heifers of the crossbreds hybrid reached sexual maturity earlier but did not affect the lower age at first calving. Dividing the cows into age categories provided a more detailed perspective of the impact of genotypic differences on reproductive and metabolic profiles in PHF and PHF × SRB cattle. The findings highlight the importance of considering age-specific effects when assessing the performance and health of dairy cattle with diverse genotypes.

CONCLUSIONS

The choice between PHF and PHF × SRB should depend on the specific goals and priorities of the cattle farming operation. Factors such as overall milk yield requirements, market demands, reproductive management strategies, and health considerations should be carefully evaluated to determine the most suitable breed for a given farming context.

Relationship Between Facility Type and Bulk Tank Milk Bacteriology, Udder Health, Udder Hygiene, and Milk Production on Vermont Organic Dairy Farms

The primary objective of this cross-sectional observational study was to determine whether bulk tank milk quality, udder health, udder hygiene and milk production outcomes were associated with facility type on organic dairies. A secondary objective was to identify other management-related risk factors associated with bulk tank milk quality, udder health, udder hygiene, and milk production on organic dairy herds in Vermont. We aimed to enroll 40 farms, to compare herds using the 2 most common systems (freestalls, tiestalls) for housing organic dairy cattle in the state with those using a bedded pack during the non-grazing season (typically November-May). Two general styles of bedded packs were observed: cultivated bedded packs and untilled deep bedded packs. Due to the limited number of herds using bedded packs to house lactating dairy cattle in Vermont, we combined untilled and cultivated bedded packs to describe udder hygiene, milk quality, and udder health on these loose-housing systems deeply-bedded with organic material. The study was completed on 21 farms (5 bedded packs, 6 freestalls, 10 tiestalls) before interruption due to the COVID-19 pandemic. Data captured from Dairy Herd Improvement Association records from the test closest to the date of the farm visit included average somatic cell score (SCS), standardized 150-d milk (pounds), % cows with current high SCS (SCS ≥ 4.0), % cows with newly elevated SCS (previous SCS < 4.0 to current ≥ 4.0), and % cows with chronically elevated SCS (SCS ≥ 4.0 last 2 tests). Multivariable linear regression models were used to describe outcomes by facility type, but suffered from limited statistical power due to small group sample sizes. Unconditional comparisons failed to find statistically significant differences between farms grouped by facility type in metrics captured from Dairy Herd Improvement Association test data, bulk tank milk somatic cell count (BTSCC) and aerobic culture data, or udder hygiene scores. A secondary analysis was conducted using univariate linear regression to identify associations between herd management factors and outcomes for all 21 farms combined. Although not all differences found were statistically significant in this secondary analysis combining all farms, numeric differences that may be biologically important are reported showing farms with deeper bedding had a lower BTSCC, lower newly elevated SCS, lower chronically elevated SCS, lower elevated current SCS, lower average SCS, and better udder hygiene metrics. Farms with lower mean udder hygiene scores had numerically lower chronically elevated SCS, lower elevated current SCS, and lower average SCS. We could not reject the null hypothesis that milk quality and udder health outcomes did not differ by facility type, and this does not preclude the existence of biological differences in these outcomes between facility types. The current study provides insight on factors affecting bulk tank milk quality, udder health and hygiene measures on organic dairy farms in Vermont. Bedded packs may be a viable option for confinement housing during the winter non-grazing season for pasture-based herds interested in a loose-housing system in the Northeastern US, but more research such as longitudinal studies with a larger sample size is needed to test this hypothesis.

Vaccination protocols in Québec dairy herds

Information is needed on vaccination protocols used by veterinarians and dairy producers to prevent and control infections in dairy herds. This observational study described farm's vaccination standard operating procedures (SOP) developed by veterinarians in collaboration with dairy producers in Québec. Data pertaining to vaccination protocols and dairy producer practices were collected as part of the biosecurity component of the National Mandatory Quality Assurance Certification Program (proAction). Generalized statistical mixed-effects models were used to assess associations between dairy herd characteristics and the vaccination SOP, encompassing various vaccination types. These included any vaccination, core vaccines only (bovine respiratory syncytial virus, infectious bovine rhinotracheitis herpesvirus, parainfluenza virus type 3, bovine viral diarrhea virus type 1 and type 2) and vaccination against diarrhea, mastitis, or clostridial diseases. These models accounted for random variations related to clustering by veterinarians and veterinary clinics. Furthermore, the variance of the outcome was partitioned into producer, veterinarian, and veterinary clinic levels to explore the proportion of the total variance attributable to each group. A total of 3,759 standardized vaccination procedures completed between 2018 and 2021 were analyzed. At least one vaccination target was included in the vaccination SOP in 89% of the dairy herds. The most frequently included vaccine in the SOP was core vaccines, comprising 88%, followed by mastitis (22%), neonatal diarrhea (18%), and clostridial diseases (15%). The vaccination SOPs, particularly core, mastitis, and diarrhea vaccinations, mainly varied due to the veterinarian's characteristics, followed by the clinic's characteristics. In contrast, the decision to included clostridial vaccination primarily varied with the veterinary clinic (76%). Organic producers generally included fewer vaccinations in their SOPs, including core vaccines, than conventional producers. In addition, producers who were providing access to pasture had fewer vaccination SOP for vaccination against mastitis and neonatal diarrhea but more vaccination SOP for clostridial vaccination.

Associations between early lactation intramammary infections and udder health and performance during the first 180 days in milk in first-lactation organic dairy cows

Prior data from our group showed that first-lactation cows under organic management in United States have a high prevalence of Staphylococcus aureus, Streptococcus spp., and Staphylococcus chromogenes intramammary infections (IMI) in early lactation. Nonetheless, the relationship between IMI, udder health, and milk production in organically reared primiparous cows remains elusive. The objectives of this observational study were to investigate the relationship between presence and persistence of IMI in the first 35 d in milk (DIM) and somatic cell count (SCC) and milk production during the first 6 mo of lactation on first-lactation organic dairy cows. The analysis included a total of 1,348 composite milk samples collected during the first 35 DIM that were submitted for milk culture and 1,674 Dairy Herd Improvement Association (DHIA) tests during the first 180 DIM from 333 heifers in 4 organic dairy farms, enrolled between February 2019 and January 2020. The association between IMI in the first 35 DIM and new high SCC (SCC > 200,000 cells/mL) and milk production during the first 6 mo of lactation was investigated using Cox proportional hazards regression and mixed linear regression, respectively. The association between IMI persistence (harboring the same microorganism as reported by the laboratory for 2 or more samples) in the first 35 DIM and number of DHIA tests with high SCC during the first 6 mo of lactation was modeled using negative binomial regression. The presence of IMI by Staph. aureus (hazard ratio [HR] [95% confidence interval {CI}]: 3.35 [2.64, 4.25]) or Streptococcus spp. (HR [95% CI]: 2.25 [2.12, 2.39]) during the first 35 DIM was associated with an increased risk of new high SCC during the first 6 mo of lactation. Milk production was reduced when Streptococcus spp. were identified in milk samples. However, there was no evidence of a difference in milk production in Staph. aureus IMI. Isolation of non-aureus staphylococci and mammaliicocci was related to a mild increase in the hazards of high SCC (HR [95% CI]: 1.34 [0.97, 1.85]) and a decrease in milk production during one or more postpartum tests. Presence of gram-negative or Streptococcus-like organisms IMI was not associated with either high SCC or milk production. Presence of Bacillus IMI was associated with a lower hazard of new high SCC (HR [95% CI]: 0.45 [0.30, 0.68]), and higher milk production during the first 180 d of lactation (overall estimate [95% CI]: 1.7 kg/d [0.3, 3.0]). The persistence of IMI in the first 35 DIM was associated with the number of tests with high SCC during the lactation for all microorganisms except for Staphylococcus chromogenes. Therefore, our results suggest that the persistence of IMI in the first 35 DIM could be an important factor to understand the association between IMI detected in early lactation and lactational SCC and milk production in organic dairy heifers. Our study described associations between IMI, udder health, and milk production in first-lactation organic dairy cows that are consistent with findings from conventional dairy farms.

Identification of Genomic Instability in Cows Infected with BVD Virus

An important factor for dairy cattle farmers is the profitability of cattle rearing, which is influenced by the animals' health and reproductive parameters, as well as their genomic stability and integrity. Bovine viral diarrhea (BVD) negatively affects the health of dairy cattle and causes reproductive problems. The aim of the study was to identify genomic instability in cows with reproductive disorders following infection with the BVD virus. The material for analysis was peripheral blood from Holstein-Friesian cows with reproductive problems, which had tested positive for BVD, and from healthy cows with no reproductive problems, which had tested negative for BVD. Three cytogenetic tests were used: the sister chromatid exchange assay, fragile sites assay, and comet assay. Statistically significant differences were noted between the groups and between the individual cows in the average frequency of damage. The assays were good biomarkers of genomic stability and enabled the identification of individuals with an increased frequency of damage to genetic material that posed a negative impact on their health. The assays can be used to prevent disease during its course and evaluate the genetic resistance of animals. This is especially important for the breeder, both for economic and breeding reasons. Of the three assays, the comet assay proved to be the most sensitive for identifying DNA damage in the animals.

Investigation of intramammary infections in primiparous cows during early lactation on organic dairy farms

Previous studies have shown that organically raised dairy cows have an increased prevalence of Staphylococcus aureus compared with conventionally raised dairy cows. However, little information exists about the dynamics of intramammary infection (IMI) in primiparous cows during early lactation on organic dairy farms. The objective of this study was to describe the IMI dynamics of primiparous cows on certified organic farms during early lactation. This longitudinal study enrolled 503 primiparous cows from 5 organic dairy farms from February 2019 to January 2020. Quarter-level milk samples were collected aseptically on a weekly basis during the first 5 wk of lactation. Samples were pooled by cow and time point into composite samples inside a sterilized laminar hood and submitted for microbiological culture. For each of the different microorganisms identified, we estimated the prevalence in each postpartum sample, period prevalence (PP), cumulative incidence, and persistence of IMI. Logistic regression models were used to investigate whether the prevalence of IMI differed by farm or sampling time points and whether IMI persistence differed between detected microorganisms. Our findings revealed a high prevalence of Staphylococcus aureus (PP = 18.9%), non-aureus staphylococci and closely related mammaliicoccal species (PP = 52.1%), and Streptococcus spp. and Streptococcus-like organisms (PP = 32.1%) within the study population. The prevalence of these microorganisms varied significantly between farms. Staphylococcus aureus and Staphylococcus chromogenes exhibited significantly higher IMI persistence compared with other detected bacterial taxa, confirming the divergent epidemiological behavior in terms of IMI chronicity across different microorganisms. This study improves our understanding of the epidemiology of mastitis-causing pathogens in organically raised primiparous cows, which can be used to tailor mastitis control plans for this unique yet growing subpopulation of dairy cows.

Associations of production characteristics with the on-farm presence of Fasciola hepatica in dairy cows vary across production levels and indicate differences between breeds

Fasciola hepatica is one of the economically most important endoparasites in cattle production. The aim of the present work was to evaluate the relevance of production level on the associations of on-farm presence of F. hepatica with farm-level milk yield, milk fat, and milk protein in Holstein cows, a specialised dairy breed, and in Simmental cows, a dual purpose breed. Furthermore, we investigated whether differential associations were present depending on breed. Data from 560 dairy farms across Germany housing 93,672 cows were analysed. The presence of F. hepatica antibodies was determined via ELISA on bulk tank milk samples. Quantile regression was applied to model the median difference in milk yield, milk fat, and milk protein depending on the interaction of breed and fluke occurrence. Whereas a reduction in milk yield (-1,206 kg, p < 0.001), milk fat (-22.9 kg, p = 0.001), and milk protein (-41.6 kg, p <0.001) was evident on F. hepatica positive German Holstein farms, only milk fat (-33.8 kg, p = 0.01) and milk protein (-22.6 kg, p = 0.03) were affected on F. hepatica positive German Simmental farms. Subsequently, production traits were modelled within each of the two breeds for low, medium, and high producing farms in the presence of F. hepatica antibodies and of confounders. On Holstein farms, the presence of F. hepatica seropositivity was associated with lower production, while on German Simmental farms such an association was less evident. This work demonstrates that production level is relevant when assessing the associations between the exposure to F. hepatica with production characteristics. Moreover, both models indicate a breed dependence. This could point towards a differential F. hepatica resilience of specialised dairy breeds in comparison with dual purpose breeds.

Organic Milk Production and Dairy Farming Constraints and Prospects under the Laws of the European Union

In recent years, there has been rapid development in organic farming. When choosing organic livestock products, consumers are guided by the conviction that animals are provided with the highest welfare standards and access to pasture. The purpose of this article was to trace the principles of organic farming prevailing in the EU with regard to milk production and cattle breeding. The principles of organic production are universal and their application is not limited to certified farms. Organic certification is intended to assure the consumer of the quality and method of production. Due to additional requirements imposed by law, organic cows are usually kept in better welfare conditions compared to conventional cattle, but this is not the rule. The altered taste and texture of organic milk and its products compared to conventional products mainly depends on the presence of pasture greens in the cows' diet. Therefore, milk from conventionally kept, pasture-grazed cows may have similar characteristics and composition. Organic farms tend to have lower milk yields compared to conventional farms due to the lower consumption of concentrate feed. In the future, it is expected that the proportion of land that is unsuitable for the production of crops for human consumption will increasingly be used for cow grazing.

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.

Managing organic dairy herd health: Current roles and possible future roles for veterinarians with organic dairy clientele

This study aimed to understand the veterinary-client relationship and perspectives in organic dairy production systems. Twenty-three organic dairy producers and 12 veterinarians were interviewed using semi-structured, one-on-one interviews. Consultation with local veterinarians was typically infrequent, as there was greater reliance on other producers and organic industry professionals for advice on dairy herd health management, perhaps due to a shared focus on organic farming principles. Organic producers generally consulted local veterinarians most frequently to develop vaccine protocols, address animal health emergencies, and gain reproductive services. Common reasons organic producers cited for not regularly consulting a local veterinarian included the cost of veterinary services and a perception that local veterinarians have limited experience with organic systems and products. Some producers also expressed the idea that infrequent veterinarian usage is indicative of a healthy herd. Meanwhile, local veterinarians reported that organic dairy producers often delayed consulting them about individual cases until animal health problems were severe. Local veterinarians also identified challenges in servicing organic herds, such as the lack of standardized regulations between different organic certifiers and limited safety and efficacy data for many herd health products used by organic producers. In addition, their formal training generally did not include organic herd health strategies. Organic dairy clients were typically a small fraction of the overall workload for local veterinarians, which precluded their ability to accumulate experience. In contrast, a handful of specialized veterinarians in the organic milk processing industry work more frequently with organic producers and have published most of the available resource materials on organic dairy herd health. Veterinary-client partnerships could be improved through more open communication and discussion of the challenges identified in this study and through participatory research and outreach engagement that includes local veterinarians, organic certifiers, organic industry veterinarians, and producers.

Design and implementation of a survey quantifying winter housing and bedding types used on Vermont organic dairy farms

We conducted a descriptive observational study to quantify the frequency and diversity of winter housing and bedding types used by organic dairy farmers in Vermont. This report describes the survey methods, results, successes, limitations, and lessons learned from administering the survey. Beginning in December 2018, a short questionnaire was administered by web, mail, and telephone to a source population defined as all producers of organic dairy cow milk in Vermont (n = 177) listed in the United States Department of Agriculture Organic Integrity database. Our approach yielded an 82% (n = 145) response from certified organic farms producing cow milk in Vermont at the time of the survey. The 3 most common housing and bedding material combinations used by respondents were tiestall housing with wood (sawdust or shavings) bedding materials (45%), freestall housing with wood bedding materials (14%), and freestall housing with sand bedding (12%). Fifteen percent of respondents reported using more than one type of facility for winter housing of lactating cattle. The median number of lactating cows on farms among respondents was 59.5 (range: 2-400), and the odds of using more than one type of facility to house lactating cows increased positively with the number of lactating cows reported for a herd. Breed distribution was similar across the housing and bedding type categories. An association between frequency of individual cow milk somatic cell count testing and housing type was identified; respondents using freestall sand facilities tested less frequently than respondents using tiestalls with wood bedding. Although the questionnaire length limited the amount of information gathered, the response proportion was exceptional, and overall our survey results provide valuable insight on Vermont organic dairy housing and bedding practices that should inform future extension and outreach efforts for this sector of the dairy industry.

Genetic parameters for stayability of Holsteins in US organic herds

The objectives of this study were to estimate genetic parameters for stayability in US organic Holstein dairy cows and estimate genetic correlations with nationally evaluated traits of interest. Stayability is the binary trait for success or failure to remain in the herd until a given time point. We used birth, calving, and cull dates from 16 USDA certified organic farms recommended by industry personnel as herds maintaining individual cow records and using artificial insemination. Stayability at 5 time points was assigned based on the presence of a calving date for each parity up to 5 (STAY1 to STAY5). We also considered livebirth (vs. stillbirth), stayability from a successful first calving to second calving (STAY12), stayability from a successful second calving to third calving (STAY23), and stayability as a repeated measure encompassing STAY1 to STAY5. In total, 44,995 females were used in this study. Ninety-six percent were born alive and of these, 64% reached first parity. Animals with Holstein sires and no other identified breed for 3 generations on the maternal side were included. Heritabilities for stayability to each parity on the underlying scale were estimated using a threshold model with the fixed effect of herd and the random effects of animal and herd-year-season of birth. Genetic correlations were estimated among livebirth, STAY1, STAY12, and STAY23 with a 4-trait linear model with fixed herd-year-season of birth and random effects of animal, dam of the calf (livebirth), and herd calving date (STAY12 and STAY23). Heritabilities for stayability ranged from 0.07 to 0.15 and was 0.08 for the direct effect of livebirth and 0.06 for the maternal effect of livebirth. The repeatability for stayability was 0.60. Genetic correlations ranged from 0.11 between livebirth and STAY1 to 0.83 between STAY12 and STAY23. Excluding livebirth, stayability to all time points was significantly correlated with productive life and with cow livability. In general, stayability was positively associated with milk yield and negatively associated with fat percent and stillbirth. In conclusion, stayability in organic herds is heritable and positively associated with nationally evaluated longevity traits suggesting that improvement for stayability in organic herds can be achieved with current national evaluations for longevity.

Organic dairy producer experiences and decisions related to disease prevention and treatment

Organic dairy producers have distinct perspectives, approaches, challenges, and experiences when managing herd health, but little research has been conducted to develop a deeper understanding of producer decision-making related to disease-prevention and treatment strategies. We used 23 semi-structured interviews with organic dairy producers to better understand their perceived herd health challenges and overall disease-prevention strategies; decision-making and attitudes related to vaccination; and approaches to the treatment of infectious diseases using alternative or conventional antimicrobial therapies. Organic dairy producers reported improvements in overall animal health after they transitioned from a conventional to an organic system. Outdoor access, a balanced forage-based diet, and animal and environmental cleanliness were reported as the predominant disease-prevention measures. Over half of producers vaccinated their animals, and almost all preferred to use vaccines sparingly. Among producers who did not use vaccines, reasons cited were low perceived risk for infectious disease and minor vaccine safety concerns, yet many were not opposed to using vaccines in the future. Non-antimicrobial therapies were viewed as alternative effective treatment strategies for most common infectious diseases. Producers used antimicrobials very rarely and generally reserved them for severe cases when alternative treatments failed. Because US organic standards prohibit selling milk from cows that have ever been treated with antimicrobials, producers described the decision to use antimicrobials as extremely challenging and involved balancing considerations of economics, convenience, and animal welfare. This research fosters a better understanding of organic dairy producers' disease-prevention and treatment strategies and could be used by veterinarians and other animal health specialists to facilitate services for organic clients.

Milk Production, Body Weight, Body Condition Score, Activity, and Rumination of Organic Dairy Cattle Grazing Two Different Pasture Systems Incorporating Cool- and Warm-Season Forages

Simple Summary

Organic dairy cows were used to evaluate the effect of two pasture production systems on milk, fat, and protein production, somatic cell score, milk urea nitrogen, body weight, body condition score, and activity and rumination. Milk production increased when cows grazed sorghum-sudangrass compared to when they grazed perennial grasses and legumes. Warm-season annual grasses may be incorporated into grazing systems for organic dairy cattle while maintaining milk production and components.

Abstract

Organic dairy cows were used to evaluate the effect of two organic pasture production systems (temperate grass species and warm-season annual grasses and cool-season annuals compared with temperate grasses only) across two grazing seasons (May to October of 2014 and 2015) on milk production, milk components (fat, protein, milk urea nitrogen (MUN), somatic cell score (SCS)), body weight, body condition score (BCS), and activity and rumination (min/day). Cows were assigned to two pasture systems across the grazing season at an organic research dairy in Morris, Minnesota. Pasture System 1 was cool-season perennials (CSP) and Pasture System 2 was a combination of System 1 and warm-season grasses and cool-season annuals. System 1 and System 2 cows had similar milk production (14.7 and 14.8 kg d⁻¹), fat percentage (3.92% vs. 3.80%), protein percentage (3.21% vs. 3.17%), MUN (12.5 and 11.5 mg dL⁻¹), and SCS (4.05 and 4.07), respectively. Cows in System 1 had greater daily rumination (530 min/day) compared to cows in System 2 (470 min/day). In summary, warm-season annual grasses may be incorporated into grazing systems for pastured dairy cattle.

Health and welfare in organic livestock production systems—a systematic mapping of current knowledge

This review aimed to systematically map and summarize the status of animal health and welfare in organic production. The prevalence of diseases and behavioural effects in organic dairy cow, beef cattle, sheep, pig, laying hen and broiler chicken were discussed in the context of the organic values and current knowledge on animal health and welfare. In total 166 peer-reviewed scientific publications between 2008 and 2020 were included. No strong evidence for neither inferior nor distinctly higher animal welfare in organic compared with conventional production could be supported. The welfare status of organic livestock is in general good in relation to the OIE definition of animal health and welfare. However, organic systems are still facing several challenges related to animal health and the arising of goal conflicts due to management and practical implications. Greater possibilities to perform species-specific behaviours in organic production systems, however, indicate that the organic standards offer a good framework for high animal welfare management. For organic dairy farmers, the main health problems are similar to those of non-organic farms; especially mastitis and lameness need improvement. Parasites, together with mastitis and lamb mortality, are important welfare issues in organic sheep production. Piglet mortality, leg problems, parasite load and increasing respiratory problems are of major relevance in organic pig production. For organic laying hens, major health challenges relate to feather pecking and cannibalism, parasites and possibilities to express species-specific behaviours. For organic broilers, dermatitis of footpads, hocks and breast are reported as main health issues.

Incidence and risk factors for reproductive disorders in organic certified dairies

The objective was to determine the lactational incidence risks of reproductive disorders (RD) including dystocia (DYS), retained fetal membranes (RFM), puerperal metritis (PM), clinical endometritis (CE), pyometra (PYO), late pregnancy loss (LPL), and culling due to reproductive reasons (CRR) in large organic certified dairies with predominant use of Holstein genetics. In addition, potential risk factors for RD, including parity category, milk yield in the previous lactation, season of dry-off, access to grazing at dry-off, length of the dry period (DPL), length of the close-up period (CUPL), calculated gestation length (CGL), season of calving, access to grazing at calving, concurrent health conditions, and total number of artificial inseminations were analyzed. A retrospective study was performed using information from 8 organic certified herds located in northern Colorado and west Texas, ranging from 900 to 6,000 milking cows. Cow information consisted of finalized lactations starting with calvings occurring between January 1, 2016, and December 31, 2018. Data were analyzed using time-to-event analyses and multivariable logistic regression. Clinical endometritis had the greatest lactational incidence risk (incidence risk = 10.1%; 95% CI = 9.8-10.3%), followed by DYS (8.8%; 8.5-9.1%), PM (4.9%; 4.7-5.1%), PYO (4.0%; 3.8-4.1%), LPL (3.6%; 3.4-3.7%), and RFM (2.0%; 1.8-2.1%). The incidence risk of CRR was 7.5% (7.3-8.7%), representing 29.1% (28.4-30.0%) of all culling reasons. Median time from calving to diagnosis of PM, CE, PYO, and LPL were 6, 23, 111, and 228 d, respectively. Median time for CRR was 391 d. The main risk factors for RD were DPL, CGL, and CUPL. Season of dry-off was a risk factor for RFM, PM, CE, LPL, and PYO. Short DPL (<30 d) was associated with increased odds (95% CI) of RFM [2.1 (1.6-2.7)], PM [1.4 (1.2-1.7)], and LPL [2.5 (1.5-4.2)]. Shortened CGL (<270 d) increased the odds of DYS [1.5 (1.3-1.8)], RFM [3.2 (2.4-4.1)], and PM [2.4 (1.7-3.3)], whereas extended CGL (>285 d) increased the odds of DYS [1.5 (1.4-1.7)], PM [1.5 (1.2-2.0)], CE [1.5 (1.1-2.0)], and CRR [1.2 (1.10-1.4)]. Shortened CUPL was associated with increased odds of all the RD. Cows spending less than 7 d in the close-up groups had greater odds of DYS [1.4 (1.1-1.8)], RFM [2.1 (1.8-2.4)], PM [1.9 (1.6-2.1)], PYO [1.5 (1.2-1.8)], LPL [2 (1.7-2.3)], and CRR [1.4 (1.04-1.8)] compared with cows spending more than 14 d in the close-up group. Season of calving was associated with the odds of PM [summer = 1.13 (1.01-1.2)], PYO [summer = 1.7 (1.1-2.5)], and LPL ([fall = 0.8 (0.6-0.96)] compared with winter calving. Other risk factors affecting RD were parity number, total number of artificial inseminations, and concurrent health conditions. Overall, lactational incidence risks of reproductive diseases were comparable with those reported in conventional herds. The identified risk factors for RD open opportunities for interventions, especially focused in precalving management, estimation of due dates, and closer monitoring of pregnancies from natural services in large organic certified dairy herds.

Symposium review: Comparisons of feed and milk nitrogen efficiency and carbon emissions in organic versus conventional dairy production systems

Evaluation of feed efficiency (FE; calculated as energy-corrected milk yield/dry matter intake) and milk nitrogen efficiency (MNE; calculated as milk N yield/N intake) is needed to help farmers make decisions regarding the economic and environmental sustainability of dairy farms. Our primary objective was to compare FE and MNE data obtained from studies conducted with organic versus conventional dairy cows. Specifically, 3 data sets were constructed to meet this goal: (1) the organic Jersey data set (ORG-JE) built with studies (n = 11) done at the University of New Hampshire Burley-Demeritt Organic Dairy Research Farm (Lee, NH), (2) the conventional Jersey data set (CON-JE) constructed using 19 experiments reported in the literature, and (3) the organic non-Jersey-breed (mostly Holstein, Swedish Red, and Norwegian Red) data set (ORG-NJE) created with 11 published studies. Comparisons were made between ORG-JE and CON-JE and between ORG-JE and ORG-NJE. A second objective was to compare the enteric methane (CH₄) emission data set from studies using organic Jerseys (n = 5) with those using conventional Jerseys (n = 4). Cows used in the ORG-JE data set had lower FE (-16%) and MNE (-15.5%) than cows used in the CON-JE counterpart, possibly because dry matter intake increased by an average of 10.4% in organic cows. Feed efficiency and MNE computed from cows belonging to the ORG-NJE data set were intermediate between ORG-JE and CON-JE. Measured CH₄ intensity (g/kg of energy-corrected milk) from cows in the ORG-JE CH₄ data set increased by 71% compared with that from cows in the CON-JE CH₄ data set. Estimated FE and enteric CH₄ emissions revealed that Wisconsin organic dairies with the heaviest reliance on forage sources and longest grazing time during the summer were the least feed efficient and emitted the greatest amount of CH₄ per kilogram of energy-corrected milk at the animal and whole-farm levels. Overall, the comparisons of FE, MNE, and enteric CH₄ emissions between organic and conventional dairies and within organic systems made in this symposium review should be interpreted cautiously because they are based on study means and small data sets. Research is needed to better characterize the performance, efficiency, profitability, and carbon emissions of forage-based organic dairies in the United States, including the fast-growing "grass-fed" segment, which relies exclusively on forage diets. The effect of large organic dairies on the economic and social sustainability of small and mid-size organic dairy operations nationwide also deserves further investigation.

Supplementation strategies affect the feed intake and performance of grazing replacement heifers

The literature lacks studies investigating the performance of supplemented replacement heifers grazing on intensively managed warm-season pasture. Our objective was to evaluate the effects of supplement composition (energetic or protein) on the performance, muscle development, thermogenisis, nutrient intake, and digestibility of replacement Holstein heifers grazing Mombaça grass. Eighteen Holstein heifers with an average age and initial body weight (BW) of 12.57 ± 2.54 mo and 218.76 ±47.6 kg, respectively, were submitted to a randomized block design, with six replicates on a rotational grazing system of Panicum maximum cv. Mombaça pasture. Treatments were: control (CON; mineral salt ad libitum); energy supplement (ENE; corn meal as supplement, 8% CP and 3.78 Mcal/kg DE); and protein supplement (PRO; corn and soybean meal, 25% CP and 3.66 Mcal/kg DE). Supplements were individually fed at 0.5% BW. The experiment lasted 120 days, subdivided into three periods. Titanium dioxide and indigestible neutral detergent fiber (iNDF) were used to estimate the intakes and digestibility of the nutrients. BW, wither height, thoracic circumference, body length, and ultrasound of ribeye fat thickness measurements were taken once per period. Body condition score (BCS) was assessed twice during the experiment. The MIXED procedure of SAS, including period as a repeated measure, was used and significance was declared at P ≤ 0.05. Dry matter intake (DMI), CP intake (CPI) and DE intake were greater in heifers fed PRO compared to CON and ENE. Heifers supplemented with ENE had the lowest DMI. Treatment affected pasture intake/BW; it was similar between PRO and CON heifers, and lower for the ENE treatment. A treatment × period interaction was observed for NDF intake (%BW), in which heifers fed PRO and CON had the greatest NDF intake and ENE had the lowest. The digestibility of DM was the greatest in PRO-supplemented heifers and the lowest in CON heifers. Heifers fed ENE had decreased CP digestibility compared to PRO and CON heifers. Average daily gain (ADG) and thoracic circumference gain were greatest in the PRO treatment. BCS was greater in PRO compared to CON and ENE heifers. Supplementing Holstein heifers at 0.5% BW using PRO supplementation resulted in better animal performance, primarily greater ADG, than feeding ENE or not supplementing (CON). In conclusion, our results indicate that dairy heifers should be fed a protein supplement when grazing intensively managed Mombaça grass pasture.

Production level, fertility, health traits, and longevity in local and commercial dairy breeds under organic production conditions in Austria, Switzerland, Poland, and Sweden

Our aim was to map the performance of local (native) dairy cattle breeds in Austria, Switzerland, Poland, and Sweden with regard to production, fertility, longevity, and health-associated traits and to compare them with commercial (modern) breeds. For this purpose, we analyzed test-day records (July 1, 2011, to June 30, 2014) and treatment records (Austria, Sweden) of cows managed on organic farms. We performed country-wise comparisons of 123,415 lactations from Original Braunvieh (OB) and Grey Cattle (AL) with Braunvieh (BV; Brown Swiss blood >60%) in Switzerland; AL with BV (Brown Swiss blood >50%) in Austria; Polish Black and White (ZB), Polish Red and White (ZR), and Polish Red (RP) with Polish Holstein Friesian (PHF) in Poland; and Swedish Red (SRB) with Swedish Holstein (SH) in Sweden. Average milk yields were substantially lower for local compared with commercial breeds in all countries; differences ranged from 750 kg (Sweden) to 1,822 kg (Austria), albeit on very different average levels. Local breeds showed a longer productive lifetime by 0.64, 0.83, 1.42, and 0.20 lactations in Switzerland, Austria, Poland, and Sweden, respectively, again on very different levels in each country. Regarding fertility traits, calving interval was shorter in local than in commercial breeds by 13 (Sweden), 14 (Switzerland), and 20 d (Austria, Poland). Insemination index was lower in certain local breeds by 0.15 (Switzerland), 0.14 (Austria), 0.21 (Poland), and 0.13 (Sweden). Several local breeds showed a lower proportion of cows with >100,000 somatic cells/mL. This was the case in Switzerland (OB 24.2%; BV 35.8%), Austria (AL 25.3%; BV 36.9%), and Sweden (SRB 42.4%; SH 43.4%). In contrast, the respective proportion in Poland exceeded 82% in all breeds except the commercial PHF (76.1%). In Sweden, lactations with veterinary treatments were considerably less prevalent in SRB (15.6%) than in SH (21.7%). In Austria, breeds differed only in treatments for udder disorders, which favored AL. In conclusion, the markedly lower milk yields of local breeds are partly counterbalanced by (somewhat inconsistent) advantages in longevity, fertility, and health traits across 4 European countries. This indicates that the robustness of local breeds can contribute to improved sustainability of organic dairy systems.

Effects of winter housing systems on production, economics, body weight, body condition score, and bedding cultures for organic dairy cows

Certified-organic dairy cows (n = 268) were used to evaluate the effect of 2 winter (December to April) housing systems on milk production, somatic cell score (SCS), body weight, body condition score (BCS), and economics across 3 winter seasons (2013, 2014, and 2015). Bedding cultures from the housing systems were also evaluated. Cows were randomly assigned to 2 treatments (2 replicates per group): (1) outdoor (straw pack, n = 140) or (2) indoor (3-sided compost bedded pack barn, n = 128). Cows calved during 2 seasons (spring or fall) at the University of Minnesota West Central Research and Outreach Center, Morris, Minnesota, organic dairy. Milk, fat, and protein production and SCS were recorded from monthly milk recording. Body weight and BCS were recorded biweekly as cows exited the milking parlor. Bedding cultures from the housing systems were collected biweekly. Costs for key inputs and the price received for milk production were recorded for the study period and averaged for use in the profitability analysis. Energy-corrected milk and SCS were not different for the outdoor (15.1 kg/d, 2.64) and indoor (15.7 kg/d, 2.57) housing systems, respectively. In addition, cows in the outdoor and indoor housing systems were not different for body weight (528 vs. 534 kg) and BCS (3.22 vs. 3.23), respectively. Daily dry matter intake was 19.1 kg/d for the outdoor cows and 19.6 kg/d for indoor cows. The total bacteria count from bedding samples tended to be lower in the outdoor (13.0 log₁₀ cfu/mL) compared with the indoor (14.9 log₁₀ cfu/mL) system. Milk revenue and feed cost were not different for the 2 housing systems. Labor and bedding costs were lower and net return was higher for the outdoor housing system. The outdoor straw pack system had a $1.42/cow per day net return advantage over the indoor compost bedded pack barn. In summary, lactating cows housed outdoors on straw-bedded packs did not differ for production or SCS, or for body weight, BCS, or dry matter intake, but had greater profitability than cows housed in an indoor compost bedded pack barn.

Biosecurity and animal disease management in organic and conventional Swedish dairy herds: a questionnaire study

Background

Good animal health is a notion that is germane to organic dairy production, and it is expected that such herds would pay significant attention on the health of their animals. However, it is not known if the applied animal disease management is actually more adequate in organic dairy cattle herds than in conventional dairy herds. A questionnaire study on biosecurity and animal disease management activities was therefore conducted among Swedish farmers with organic and conventional dairy cattle herds.

Results

A total of 192 useable questionnaires were returned; response rates of 30.3 and 20.2% for organic and conventional farmers, respectively. Herd characteristics of the two herd types were very similar, except that pipeline/tie-stall systems were less common in organic farms and that organic farmers had a higher education level than their conventional counterparts. Also, very few systematic differences in general or specific disease management activities were observed between the two types of farms. The main exceptions being how milk from cows during antibiotic treatment was used, views on policy actions in relation to antibiotic use, and attitudes towards calling for veterinary support. Using milk from cows during antibiotic treatment was more common in conventional herds, although it was mainly given to bull calves. Farmers of organic herds were more positive to policy actions to reduce the use and need for antibiotics, and they reported waiting longer before contacting a veterinarian for calves with diarrhoea and cows with subclinical mastitis.

Conclusions

The stated biosecurity and animal disease management was relatively equal in Swedish organic and conventional dairy herds. Our results thus indicate that animal health is as important in conventionally managed dairy herds in Sweden as in organically managed herds.

Potential of phytoceuticals to affect antibiotic residue detection tests in cow milk in a randomised trial

Mastitis is a costly disease for dairy farmers. Some dairy farmers use herbal products, or phytoceuticals, to treat mastitis. Phytoceuticals have not been approved for this use by the United States Food and Drug Administration, and have not been tested to determine how they impact antibiotic residue detection testing. The current study tested the potential for phytoceuticals to cause positive results on two milk antibiotic residue screening tests, the Delvotest P and Charm SL Beta-lactam test, or to interfere with the detection of antibiotics by these tests.

The three phytoceuticals tested were labelled for intramammary, topical or intravulvar administration. Testing was performed in vitro using the products diluted in milk obtained from healthy organic dairy cows. Phytoceuticals were tested at concentrations ranging from 1.5 per cent to 100 per cent. Concentration levels were replicated at least twice on each milk antibiotic residue screening test. The Delvotest P is based on detection of bacterial inhibitors and no positive results were obtained for any product at concentrations less than 50 per cent. The Charm SL Beta-lactam test uses a receptor for the detection of beta-lactam antibiotics and no concentration of phytoceuticals caused an interference with these tests.

Based on dilution of the products in bovine milk at physiologically achievable levels, phytoceutical products tested at levels expected after treatment do not cause positive test results for the Delvotest P nor do they interfere with the Charm SL Beta-lactam test in detection of various antibiotics.

Organic vs. Conventional Milk: Some Considerations on Fat-Soluble Vitamins and Iodine Content

The organic food market is considerably expanding all over the world, and the related dairy market represents its third most important sector. The reason lies in the fact that consumers tend to associate organic dairy products with positive perceptions: organic milk is eco- and animal-friendly, is not produced with antibiotics or hormones, and according to general opinion, provides additional nutrients and beneficial properties. These factors justify its higher cost. These are the reasons that explain extensive research into the comparison of the differences in the amount of chemical compounds between organic and conventional milk. However, it is not simple to ascertain the potential advantage of organic food from the nutritional point of view, because this aspect should be determined within the context of the total diet. Thus, considering all the factors described above, the purpose of this work is to compare the amount of selected nutrients (i.e., iodine and the fat-soluble vitamins such as alfa-tocopherol and beta-carotene) in organic and conventional milk, expressed as the percentage of recommended daily intakes in one serving. In detail, in order to establish the real share of these biologically active compounds to the total diet, their percent contribution was calculated using the Dietary Reference Values for adults (both men and women) adopted by the European Food Safety Authority. According to these preliminary considerations, the higher cost of organic milk can mainly be explained by the high costs of the management of specific farms and no remarkable or substantial benefits in human health can be ascribed to the consumption of organic milk. In this respect, this paper wants to make a small contribution to the estimation of the potential value and nutritional health benefits of organic food, even though further studies are needed.

Economic characteristics and produced milk quality in Holstein lactating cows in organic and conventional systems

In the past decade, a global demand for products from organic agriculture has increased rapidly. Milk quality is of major interest for all parties. Therefore, the objective of this study was to compare cow performance and product quality in conventional and organic system. Holstein dairy cows (16) were allotted to one of 3 diet groups, including a conventional diet (CON), an organic system with moderate forage (OMF) and an organic system with high forage (OHF). Multiparous cows (3rd and 4th parity) were randomly assigned to the treatments. Range forages were used as part of diets, and cows were offered concentrate and silage two times a day. Daily dry matter intake (DMI) and milk yield were measured across 200 d. Furthermore, somatic cell count, feed cost and feed efficiency were determined at 20-day intervals. MY was different for cows that treated the OHF (22.5 kg/d), OMF (24.9 kg/d), and CON (28.9 kg/d) systems, respectively. Body weights were not affected by treatments; however, differences in body condition scores were observed. Although energy corrected milk and milk urea nitrogen were higher in cows fed CON system; milk fat, phytanic acid, hippuric acid and profit to cost ratio were higher in cows fed organic systems. Additionally, lower feed efficiency, feed cost and blood urea nitrogen were observed in cows fed organic diets.

Is lack of antibiotic usage affecting udder health status of organic dairy cattle?

This research communication aimed to compare somatic cell count (SCC), the main marker of udder health status, in organic farms not using antibiotics (O, n = 6), organic farms using antibiotics (OA, n = 7) and conventional farms (CA, n = 5) using antibiotic treatments, all of them at pasture. SCC was statistically significantly higher in O (173780) compared to CA (93325) and OA (107152). Milk yield had a significant diluting effect on SCC and differences between groups increased with parities. Stratified analysis of SCC depending on lactation number and % of monthly SCC test with different linear scores (LS) indicated that there is no difference in udder health in the primiparous heifers from the three groups of farms, but it deteriorates in older cows because of chronic infections in O (possibly due to lack of antibiotic use). Our results suggest that the non-use of antibiotics had an effect in udder health leading to higher occurrence of clinical and subclinical mastitis. Therefore, preventive management practices for mastitis control are essential in organic farms.

Characterisation of smallholding dairy farms in southern Brazil

Smallholder dairy farmers that are responsible for 90% of the milk produced in Santa Catarina State, in southern Brazil, transitioned in recent decades from milk production for self-consumption to commercial dairying. The objective of this study was to identify groups sharing common characteristics, potentials and limitations and compare their main management practices, milk production and milk quality. We collected data from 124 farms distributed in 24 municipalities, using semi-structured interviews, inspection of the housing and milking environment, and live observations during one complete milking. Multivariate analyses revealed three groups of farmers: ‘Semi-Intensive’ (n = 51), ‘Pasture-Based’ (n = 50), and ‘Extensive’ (n = 23). Group differences included land and herd size (both larger in Semi-Intensive, P < 0.002); feeding management of dairy cows (e.g. greater use of pasture improvement techniques in Extensive and Pasture-Based, and more efficient rotational grazing management in Pasture-Based, P < 0.04); use of external inputs (e.g. lower use of concentrate and silage in Pasture-Based, P < 0.001); milking infrastructure and hygiene practices (better in Semi-Intensive, P < 0.04), and milk productivity (greater in Semi-Intensive, P < 0.001). The Extensive group conserves several features of the subsistence, traditional mode of milk production, and makes inefficient use of costly feeding practices, which threatens its sustainability. The two other groups of farms took different, almost opposite directions to deal with the limitations in farm area: the Semi-Intensive group have adopted an entrepreneurial farming style and the Pasture-Based, a more agroecological path. These results highlight the need to develop specific strategies and policies to help these different types of producers to coexist in the dairy production chain.

Effect of feeding warm-season annuals with orchardgrass on ruminal fermentation and methane output in continuous culture

A 4-unit, dual-flow continuous culture fermentor system was used to assess nutrient digestibility, volatile fatty acids (VFA) production, bacterial protein synthesis, and methane (CH₄) output of warm-season annual grasses. Treatments were randomly assigned to fermentors in a 4 × 4 Latin square design using 7 d for adaptation to treatment and 3 d for sample collection. Treatments were (1) 100% orchardgrass (Dactylis glomerata L.; ORD); (2) 50% orchardgrass + 50% Japanese millet [Echinochloa esculenta (A. Braun) H. Scholz; MIL]; (3) 50% orchardgrass + 50% brown midrib sorghum × sudangrass (Sorghum bicolor L. Moench × S. bicolor var. sudanense; SSG]; or (4) 50% orchardgrass + 25% millet + 25% sorghum × sudangrass (MIX). Fermentors were fed 60 g of dry matter (DM)/d in equal portions of herbage 4 times daily (0730, 1030, 1400, and 1900 h). To replicate a typical 12-h pasture rotation, fermentors were fed the orchardgrass at 0730 and 1030 h and the individual treatment herbage (orchardgrass, Japanese millet, sorghum × sudangrass, or 50:50 Japanese millet and sorghum × sudangrass) at 1400 and 1900 h. Gas samples for CH₄ analysis were collected 6 times daily at 0725, 0900, 1000, 1355, 1530, and 1630 h. Fermentor pH was determined at the time of feeding, and fermentor effluent samples for NH₃-N and VFA analyses were taken daily at 1030 h on d 8, 9, and 10. Samples were also analyzed for DM, organic matter (OM), crude protein, and fiber fractions to determine nutrient digestibilities. Bacterial efficiency was estimated by dividing bacterial N by truly digested OM. True DM and OM digestibilities and pH were not different among treatments. Apparent OM digestibility was greater in ORD than in MIL and SSG. The concentration of propionate was greater in ORD than in SSG and MIX, and that of butyrate was greatest in ORD and MIL. Methane output was greatest in MIL, intermediate in ORD, and lowest in SSG and MIX. Nitrogen intake did not differ across treatments, whereas bacterial N efficiency per kilogram of truly digestible OM was greatest in MIL, intermediate in SSG and MIX, and lowest in ORD. True crude protein digestibility was greater in ORD versus MIL, and ORD had lower total N, non-NH₃-N, bacterial N, and dietary N in effluent flows than MIL. Overall, we detected little difference in true nutrient digestibility; however, SSG and MIX provided the lowest acetate to propionate ratio and lower CH₄ output than MIL and ORD. Thus, improved warm-season annual pastures (i.e., brown midrib sorghum × sudangrass) could provide a reasonable alternative to orchardgrass pastures during the summer months when such perennial cool-season grass species have greatly reduced productivity.

Comparative risk assessment for new cow-level Mycobacterium avium ssp. paratuberculosis infections between 3 dairy production types: Organic, conventional, and conventional-grazing systems

Johne's disease, a granulomatous enteritis of ruminant animals, is a hidden threat on dairy farms, adversely affecting animal welfare as well as herd productivity. Control programs in the United States advocate for specific management practices to temper the spread of the causal organism (Mycobacterium avium ssp. paratuberculosis, MAP), such as improving calving area hygiene and limiting introduction of replacement stock with unknown infection status. A need remains for direct exploration of Johne's disease prevention strategies in the United States with respect to production type. Alongside the growing demand for organic products, the safety of organic dairy practices with respect to MAP control is warranted. Further, conventional herds for which organic practices such as pasture grazing are used should be situated within the risk spectrum. We developed a risk assessment model using the US Voluntary Bovine Johne's Disease Control Program as a framework, with the goal of evaluating the risk of new cow-level MAP infections. A total of 292 organic and conventional farms in 3 states were surveyed on management practices, and an overall analysis was conducted in which each farm was first scored on individual practices using a range of "no risk" to "high risk," according to the literature. The sum of all risk factors was then analyzed to quantify and compare the risk burden for each production type. Organic herds received higher overall risk scores compared with both conventional grazing and nongrazing subtypes. To identify which factors contributed to the overall increased risk for organic herds, the management practices were categorized and evaluated by logistic regression. We determined that the increased risk incurred by organic herds was predominantly due to decisions made in the calving area and preweaned calf group. However, although certain individual risk factors related to calf management are commonly involved in prevention strategies (e.g., cow/calf separation) and were thus included in the overall risk assessment, empirical evidence linking them to the spread of MAP is lacking. Instead, these factors are problematic when executed with other management decisions, leading to a hypothesized synergism of transmission risk. To this end, we developed a set of compound risk factors, which were also evaluated as outcomes in logistic regression models, with production type serving as the predictor of interest. Organic farms in our study were more susceptible to risks associated with the synergism of study variables. Notably, organic producers were most likely to allow calves to spend extended time with the dam, while also lacking a dedicated calving area. Additionally, calves in organic herds were more often permitted to nurse even with poor udder hygiene on farm. A heightened vigilance toward calving area hygiene is therefore indicated for these herds.

Implications of PCR and ELISA results on the routes of bulk-tank contamination with Mycobacterium avium ssp. paratuberculosis

Mycobacterium avium ssp. paratuberculosis (MAP), the etiologic agent of Johne's disease in dairy cattle, may enter the bulk tank via environmental contamination or direct excretion into milk. Traditionally, diagnostics to identify MAP in milk target either MAP antibodies (by ELISA) or the organism itself (by culture or PCR). High ELISA titers may be directly associated with excretion of MAP into milk but only indirectly linked to environmental contamination of the bulk tank. Patterns of bulk-milk ELISA and bulk-milk PCR results could therefore provide insight into the routes of contamination and level of infection or environmental burden. Coupled with questionnaire responses pertaining to management, the results of these diagnostic tests could reveal correlations with herd characteristics or on-farm practices that distinguish herds with high and low environmental bulk-tank MAP contamination. A questionnaire on hygiene, management, and Johne's specific parameters was administered to 292 dairy farms in New York, Oregon, and Wisconsin. Bulk-tank samples were collected from each farm for evaluation by real-time PCR and ELISA. Before DNA extraction and testing of the unknown samples, bulk-milk template preparation was optimized with respect to parameters such as MAP fractionation patterns and lysis. Two regression models were developed to explore the relationships among bulk-tank PCR, ELISA, environmental predictors, and herd characteristics. First, ELISA optical density (OD) was designated as the outcome in a linear regression model. Second, the log odds of being PCR positive in the bulk tank were modeled using binary logistic regression with penalized maximum likelihood. The proportion of PCR-positive bulk tanks was highest for New York and for organic farms, providing a clue as to the geographical patterns of MAP-positive bulk-tank samples and relationship to production type. Bulk-milk PCR positivity was also higher for large relative to small herds. The models revealed that bulk-milk PCR result could predict ELISA OD, with PCR-positive results corresponding to high bulk-milk ELISA titers. Similarly, ELISA was a predictor of PCR result, although the association was stronger for organic farms. Despite agreement between high bulk-milk ELISA titers and positive PCR results, a large proportion of high ELISA farms had PCR-negative bulk tanks, suggesting that farms are able to maintain satisfactory hygiene and management despite a presence of MAP in these herds.

Incidence rate of pathogen-specific clinical mastitis on conventional and organic Canadian dairy farms

Mastitis is a common and costly production disease on dairy farms. In Canada, the incidence rate of clinical mastitis (IRCM) has been determined for conventionally managed dairy farms; however, no studies to date have assessed rates in organically managed systems. The objectives of this observational study were (1) to determine the producer-reported IRCM and predominant pathogen types on conventional and organic dairy farms in Southern Ontario, Canada, and (2) to evaluate the association of both mean overall IRCM and pathogen-specific IRCM with management system, housing type, and pasture access. Data from 59 dairy farms in Southern Ontario, Canada, distributed across conventional (n=41) and organic management (n=18) systems, were collected from April 2011 to May 2012. In addition to management system, farms were categorized by housing method (loose or tie-stall) and pasture access for lactating cows. Participating producers identified and collected samples from 936 cases of clinical mastitis. The most frequently isolated mastitis pathogens were coagulase-negative staphylococci, Bacillus spp., Streptococcus spp., Staphylococcus aureus, and Escherichia coli. The IRCM was higher on conventional farms than organic (23.7 vs. 13.2 cases per 100 cow-years) and was not associated with housing type (loose or tie-stall), pasture access, or herd-average milk yield. Bulk tank somatic cell count tended to be lower on conventional farms than organic (222,000 vs. 272,000 cells/mL). Pathogen-specific IRCM attributed to Staph. aureus, Bacillus spp., and E. coli was greater on conventional than organic farms, but was not associated with housing or any other factors. In conclusion, organic management was associated with reduced overall and pathogen-specific IRCM.

Comparing ELISA test-positive prevalence, risk factors and management recommendations for Johne's disease prevention between organic and conventional dairy farms in Ontario, Canada

Johne's disease (JD) is a chronic, infectious disease in cattle. Between 2010 and 2013, a voluntary JD control program was successfully launched in Ontario, Canada, including a Risk Assessment and Management Plan (RAMP) and JD ELISA testing of the entire milking herd. Over the last decade, the organic dairy sector has been growing. However, organic farming regulations and philosophies may influence the risk for JD transmission on Ontario organic dairy farms. The aim of this cross-sectional study was to investigate differences in JD ELISA test positive prevalence, risk factors for JD and recommendations for JD prevention between organic and conventional dairy herds in Ontario. RAMP results (i.e. RAMP scores and recommendations) and ELISA results were available for 2103 dairy herds, including 42 organic herds. If available, additional data on milk production, milk quality, and herd characteristics were gathered. Organic and conventional herds had a similar herd-level JD ELISA test-positive prevalence (26.2% and 27.2%, respectively). Organic herds (4.2%) had a higher within-herd JD ELISA test-positive prevalence compared to conventional herds (2.3%) if they had at least one JD test-positive animal on the farm. Organic farms had lower risk scores for biosecurity (9 points lower), and higher scores in the calving (7 points higher) and the calf-rearing management areas (4 points higher). After accounting for RAMP score, organic farms received fewer recommendations for the calving management area (Odds Ratio=0.41) and more recommendations in the adult cow management area (Odds Ratio=2.70). A zero-inflated negative binomial model was built with purchase of animals and the herd size included in the logistic portion of the model. Herd type (organic or conventional), colostrum and milk feeding practices, average bulk tank somatic cell count, and presence of non-Holstein breeds were included in the negative binomial portion of the model. Organic farms had a higher number of test positive animals (Count Ratio=2.02). Further research is necessary to investigate the apparent disconnect between risk factors and recommendations on organic dairy farms.

Farm Management in Organic and Conventional Dairy Production Systems Based on Pasture in Southern Brazil and Its Consequences on Production and Milk Quality

Simple Summary

This study provides the characteristics of the conventional high input (C-HI), conventional low input (C-LI), and organic low input (O-LI) pasture-based production systems used in Southern Brazil, and its consequences on production and milk quality. C-HI farms had larger farms and herds, annual pasture with higher inputs and milk yield, whereas O-LI had smaller farms and herds, perennial pastures with lowest input and milk yields; C-LI was in between. O-LI farms may contribute to eco-system services, but low milk yield is a major concern. Hygienic and microbiological milk quality was poor for all farms and needs to be improved.

Abstract

Pasture-based dairy production is used widely on family dairy farms in Southern Brazil. This study investigates conventional high input (C-HI), conventional low input (C-LI), and organic low input (O-LI) pasture-based systems and their effects on quantity and quality of the milk produced. We conducted technical site visits and interviews monthly over one year on 24 family farms (n = 8 per type). C-HI farms had the greatest total area (28.9 ha), greatest percentage of area with annual pasture (38.7%), largest number of lactating animals (26.2) and greatest milk yield per cow (22.8 kg·day⁻¹). O-LI farms had the largest perennial pasture area (52.3%), with the greatest botanical richness during all seasons. Area of perennial pasture was positively correlated with number of species consumed by the animals (R² = 0.74). Milk from O-LI farms had higher levels of fat and total solids only during the winter. Hygienic and microbiological quality of the milk was poor for all farms and need to be improved. C-HI farms had high milk yield related to high input, C-LI had intermediate characteristics and O-LI utilized a year round perennial pasture as a strategy to diminish the use of supplements in animal diets, which is an important aspect in ensuring production sustainability.

Invited review: organic and conventionally produced milk-an evaluation of factors influencing milk composition

Consumer perception of organic cow milk is associated with the assumption that organic milk differs from conventionally produced milk. The value associated with this difference justifies the premium retail price for organic milk. It includes the perceptions that organic dairy farming is kinder to the environment, animals, and people; that organic milk products are produced without the use of antibiotics, added hormones, synthetic chemicals, and genetic modification; and that they may have potential benefits for human health. Controlled studies investigating whether differences exist between organic and conventionally produced milk have so far been largely equivocal due principally to the complexity of the research question and the number of factors that can influence milk composition. A main complication is that farming practices and their effects differ depending on country, region, year, and season between and within organic and conventional systems. Factors influencing milk composition (e.g., diet, breed, and stage of lactation) have been studied individually, whereas interactions between multiple factors have been largely ignored. Studies that fail to consider that factors other than the farming system (organic vs. conventional) could have caused or contributed to the reported differences in milk composition make it impossible to determine whether a system-related difference exists between organic and conventional milk. Milk fatty acid composition has been a central research area when comparing organic and conventional milk largely because the milk fatty acid profile responds rapidly and is very sensitive to changes in diet. Consequently, the effect of farming practices (high input vs. low input) rather than farming system (organic vs. conventional) determines milk fatty acid profile, and similar results are seen between low-input organic and low-input conventional milks. This confounds our ability to develop an analytical method to distinguish organic from conventionally produced milk and provide product verification. Lack of research on interactions between several influential factors and differences in trial complexity and consistency between studies (e.g., sampling period, sample size, reporting of experimental conditions) complicate data interpretation and prevent us from making unequivocal conclusions. The first part of this review provides a detailed summary of individual factors known to influence milk composition. The second part presents an overview of studies that have compared organic and conventional milk and discusses their findings within the framework of the various factors presented in part one.

Productive and Economic Responses in Grazing Dairy Cows to Grain Supplementation on Family Farms in the South of Brazil

Simple Summary

In the South of Brazil, as in many regions where dairy production is pasture-based, the use of concentrate to supplement cattle diet frequently does not follow technical guidelines. This may result in inefficient management, with increased cost of production and lower pasture intake. In this study, small amounts of an energy supplement proved to be more economically efficient than a high protein commercial concentrate, despite a decrease in milk productivity. The cows were able to compensate for the lower levels of protein in the supplement with selective grazing for high protein plants. The quality of the milk was unaffected by the treatment.

Abstract

Pasture-based dairy production has been a major source of income for most family farms in the south of Brazil. Increasing milk prices have spurred an increase in grain supplementation, which has been poorly implemented, resulting in low levels of efficiency. To evaluate the consequences of supplementation on milk production and composition, grazing behavior and economic return, the widely used grain management system (CC-commercial concentrate, containing 21% CP, offered at 1 kg per 3.7 L of milk) was compared with an energy supplement (GC-ground corn, with 9.5% CP, offered at 0.4% of live weight). Ten Holstein cows were paired into two groups, and subjected to the two treatments in a crossover design. The cows remained in the same grazing group, and the grain supplement was offered individually at milking time and consumed completely. Each experimental period lasted 14 days, with 10 days for diet adaptation and four days for data collection; individual milk production and samples were collected to determine levels of fat, protein, lactose, carotenoids, vitamin A and N-urea. Grazing behavior was observed (scans every 5 min) in the first 4 h after the morning milking, and chemical composition of hand plucked samples of forage were measured. The cost of the supplement and profitability per treatment were calculated. Cows supplemented with GC consumed herbage with higher crude protein (CP: 16.23 vs. 14.62%; p < 0.05), had higher biting rate (44.21 vs. 39.54 bites/min; p < 0.03) and grazing time (22.20 vs. 20.55 scans; p < 0.05) than when receiving CC. There were no differences in milk composition between treatments (p > 0.05). However, higher concentrations of β-carotene and total carotenoids were detected in the milk of cows at 70–164 days of lactation, compared to <70 days of lactation (p < 0.05). Milk production was higher (13.19 vs. 11.59 kg/day; p < 0.05) when cows consumed CC, but resulted in lower profitability compared to GC (US$ 4.39 vs. US$ 4.83/cow per day). Our results show that higher productivity does not necessarily improve profitability. Cows receiving supplement with lower levels of protein were able to adjust their grazing behavior to meet their protein needs and this level of diet modification did not alter milk composition.

Comparison of selected animal observations and management practices used to assess welfare of calves and adult dairy cows on organic and conventional dairy farms

Differences in adoption of selected practices used in welfare assessment and audit programs were contrasted among organic (ORG; n=192) herds and similarly sized conventional grazing herds (CON-GR; n=36), and conventional nongrazing herds (CON-NG; n=64). Criteria from 3 programs were assessed: American Humane Association Animal Welfare Standards for Dairy Cattle, Farmers Assuring Responsible Management (FARM), and the Canadian Codes of Practice (CCP). Data were collected by trained study personnel during a herd visit and included information about neonatal care, dehorning, pain relief, calf nutrition, weaning, record keeping, use of veterinarians, and animal observations. Associations of management type (ORG, CON-GR, or CON-NG) with adoption of selected practice were assessed. Almost all farms (97%) met criteria suggested for age at weaning but fewer CON-NG farmers weaned calves at ≥5 wk of age compared with ORG and CON-GR farmers. Only 23% of farms met program requirements for use of pain relief during dehorning, and fewer CON-NG farmers used pain relief for calves after dehorning compared with ORG and CON-GR farmers. Calves on ORG farms were fed a greater volume of milk and were weaned at an older age than calves on CON-GR and CON-NG farms. Calves on CON-GR farms were dehorned at a younger age compared with calves on ORG and CON-NG farms. The calving area was shared with lactating cows for a larger proportion of ORG herds compared with conventional herds. About 30% of herds met welfare program criteria for body condition score but only about 20% met criteria for animal hygiene scores. The least proportion of cows with hock lesions was observed on ORG farms. Regular use of veterinarians was infrequent for ORG herds. Results of this study indicate that most of the organic and conventional farms enrolled in this study would have been unlikely to achieve many criteria of audit and assessment programs currently used in the US dairy industry.