Dairy Operations Research Articles

Prevalence Of Bovine Tuberculosis In Different Cattle Breeds In Dairy Farm In Egypt

Due to direct economic repercussions on livestock and indirect consequences for human health, knowing the prevalence rates of bovine tuberculosis is essential to define an effective control strategy. Our study was performed in 32 dairy cattle farms as we subjected 10800 dairy cattle to the Single Intradermal Comparative Tuberculin skin Test (SICTT). The skin test was interpreted according to guidelines of the World Organization for animal health (OIE). Twenty five farms (78%) have reactors to the SICTT. We also studied the relation between physiological variables with breeds, pregnancy, lactation, size of farms and the other risk factors explained in the study. Out of the 10800 tested animals, 228 (2.1%) were reactors to the skin test. The factors identified as possibly enhancing the risk of bovine tuberculosis (bTB) were herd size, age of animal, farming (housing) conditions. Other factors including breed and physiological status of the animal did not contribute to tuberculin sensitivity. The finding that large size and intensively (often poorly) managed herds were at greater risk of bovine tuberculosis and suggests that significance of bTB is increasing in Egypt parallel to an increase in the dairy operation. This surely indicates that if measures are not taken promptly, the impact of the economy and public health could be enormous. It was concluded that bTB continues to infect animals in Egypt but the prevalence was moderate, nevertheless the continued threat of economic loss in animal industry due to the persistence of bTB that should not be ignored.

Mastitis risk effect on the economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study.

The benefits and efficacy of control programs for herds infected with Mycobacterium avium subsp. paratuberculosis (MAP) have been investigated under various contexts. However, most previous research investigated paratuberculosis control programs in isolation, without modeling the potential association with other dairy diseases. This paper evaluated the benefits of MAP control programs when the herd is also affected by mastitis, a common disease causing the largest losses in dairy production. The effect of typically suggested MAP controls were estimated under the assumption that MAP infection increased the rate of clinical mastitis. We evaluated one hundred twenty three control strategies comprising various combinations of testing, culling, and hygiene, and found that the association of paratuberculosis with mastitis alters the ranking of specific MAP control programs, but only slightly alters the cost-benefit difference of particular MAP control components, as measured by the distribution of net present value of a representative U.S. dairy operation. In particular, although testing and culling for MAP resulted in a reduction in MAP incidence, that control led to lower net present value (NPV) per cow. When testing was used, ELISA was more economically beneficial than alternative testing regimes, especially if mastitis was explicitly modeled as more likely in MAP-infected animals, but ELISA testing was only significantly associated with higher NPV if mastitis was not included in the model at all. Additional hygiene was associated with a lower NPV per cow, although it lowered MAP prevalence. Overall, the addition of an increased risk of mastitis in MAP-infected animals did not change model recommendations as much as failing to consider.

On-Farm Surfaces in Contact with Milk: The Role of Staphylococcus aureus-Containing Biofilms for Udder Health and Milk Quality.

Staphylococcus aureus is a Gram-positive bacterium that causes intramammary infections and bulk tank milk (BTM) contamination in dairy operations around the world in spite of on-farm application of preventive measures. The study was conducted on a 30-cow dairy farm in the Ñuble Region of Chile. For BTM culture and somatic cell count (SCC) analysis, three consecutive BTM samples were collected. Samples for bacterial culture (n = 16) were collected from macroscopic adherence on previously washed, sanitized, and dry milking equipment surfaces in direct contact with milk during milking or cooling. A total of 48 S. aureus isolates from BTM, milking equipment, and cows' quarters with intramammary infections were analyzed by pulsed-field gel electrophoresis (PFGE). Selected milking equipment pieces were removed for biofilm visualization using scanning electron microscopy (SEM). S. aureus was isolated from all three BTM samples; the average SCC for the three BTM samples was 1,429,333 cells/mL. Fourteen of the 16 samples of milking equipment (87.5%) were culture positive for S. aureus. Biofilms were visualized by SEM in all four removed milking equipment pieces. Microorganisms observed by SEM in those biofilms were mainly coccus-shaped bacteria, and microbiological culture of these biofilms yielded viable S. aureus isolates in all samples. All pulsotypes observed among S. aureus isolates from BTM were indistinguishable from those in milking equipment surfaces. All PFGE pulsotypes observed among S. aureus isolates from biofilms on rubber liners were indistinguishable from isolates from intramammary infections in cows. Our findings suggest that milking equipment films may act as source of S. aureus contamination for BTM and cows during milking, thus compromising the microbiological quality of milk used for manufacturing dairy products.

Effect of bi-modal milk letdown on milk production

The dairy industry is relying more on hired labor to milk cows and many dairy operations are increasing pressure on employees to maintain high levels of milking parlor throughput. This management emphasis negatively impacts milking protocols that are aligned with milk quality. Parlor efficiency is often defined in terms of cows milked per hour. However, we need to consider milking efficiency to include milk quality, milk flow, and employee performance (Moore-Foster et al., 2019; Erskine et al., 2019). The purpose of this study was to determine the impact of poor pre-milking preparation (as evidenced by bi-modal milk letdown) on subsequent milk production.
 Erskine, RJ, B Norby, LM Neuder, et al. 2019. Decreased milk yield is associated with delayed milk ejection. J. Dairy Sci. (in press)
 Moore-Foster R, B Norby, RL Schewe, et al. 2019. Herd-level variables associated with delayed milk ejection in Michigan dairy herds. J. Dairy Sci. 102:696-705.

Ruminate on this

Over the past several years, the structure of the dairy industry has changed dramatically, with fewer dairy operations, larger herd sizes, higher labor costs, and a reduction of qualified labor. These factors, along with a recent explosion in the development and commercialization of sensor-based automated systems for dairy farms, have become major drivers for the automation of different farm activities. In this regard, new technologies have the ability to positively change herd management in many ways. For example, they have the potential to reduce the burden associated with health monitoring programs by reducing labor cost, improving cow time-budgets, and providing tools for more accurate and earlier disease diagnosis. Similarly, these systems can provide valuable information in other areas such as reproduction and nutrition. Still, sensor data are only useful if interpreted and used efficiently in the decision-making process. This article aims to describe current knowledge about the potential use of automated health monitoring systems (AHMS) to identify cows with health disorders, with special focus on the practical “on farm” implementation of these technologies.

Recordkeeping, treatment protocol compliance, and measuring success

The presentation will look at the entire process used to establish and maintain treatment protocols on a modern dairy. Discussion will include a process for developing new protocols, including dosage and duration of treatments, as well as withhold times. Also included in the discussion will be a means for recording all treatments correctly and consistently, as well as use of records to guide all remaining steps from retreatments to reevaluation to withhold times. The systems used are particularly suited to large modern dairy operations.

Evaluation of disease occurrence and production parameters of dairy cows treated with pegbovigrastim

Pegbovigrastim is a modified form of the naturally-occurring bovine granulocyte colony-stimulating factor. At the time of the study, pegbovigrastim was commercially available under veterinary prescription as Imrestor (Elanco Animal Health, Greenfield, Indiana). According to the product label, when the product is applied 7 days before calving and again at the day of calving, clinical mastitis incidence decreases by 28% in the first 30 days of lactation in dairy cows and heifers. The objective of this study was to further demonstrate the effectiveness of Imrestor at reducing clinical mastitis incidence, and to demonstrate the effectiveness at reducing metritis incidence in the first 30 days of lactation on a commercial dairy operation.

Evaluation of essential oils and a prebiotic for newborn dairy calves.

A blend of essential oils (EO) and a prebiotic were combined (EOC) to formulate a colostrum-based liquid birth supplement and a separate feeding supplement (Start Strong and Stay Strong, Ralco Inc., Marshall, MN). These products were designed to promote immunity and stimulate appetite to diminish health challenges and stresses experienced by newborn calves. The hypothesis was that calves supplemented with an oral dose of liquid EOC at birth (10-mL aliquot at birth and 10 mL at 12 h of age) when fed the EOC feeding supplement would result in improved growth performance, health, and immunity. The objective was to determine if an additional feeding of liquid EOC at birth in combination with EOC in the milk replacer (MR) would allow calves to demonstrate improved growth, health, and immunity compare with calves only offered EO in MR. Sixty-one Holstein calves (18 males and 43 females) from a commercial dairy operation were blocked by birth date and randomly assigned to 1 of 3 treatments. Treatments were 1) Control (CON): a 24% crude protein (CP):20% fat (as-fed basis) MR; 2) EP: a 24:20 MR with EOC mixed at 1.25 g/d; or 3) EPC: a 24:20 MR with EOC mixed at 1.25 g/d in addition to calves receiving one 10-mL oral dose of liquid EOC at birth and 10 mL again at 12 h. The 24:20 MR was fed via bucket 2 times per day at a rate of 0.57 kg/calf daily for 14 d, increased to 0.85 kg/calf at 2 times per day until 35 d and was reduced to 0.43 kg at 1 time per day at 36 d to facilitate weaning after 42 d. Decoquinate was added to the MR at 41.6 mg/kg for coccidiosis control. Calves were housed in individual hutches bedded with straw with ad libitum access to a 20% CP-pelleted calf starter and water. All data were analyzed using PROC MIXED as a randomized complete block design. Calves in this study had similar (P > 0.10) average daily gains, body weight, and growth measurements. Calves fed EPC had significantly (P < 0.05) higher IgA titers on day 0 of the trial compared with calves fed EP or CON, which was expected as calves were supplemented with liquid EOC at birth and 12 h later demonstrating an increase in immune response. The use of a liquid EOC product being administrated after birth can improve IgA titers to improve the immune status of the new born calf to fight off potential diseases and pathogens. A formulation error resulted in the EOC being fed at half the rate of the previous experiment of 2.5 g/d, which appears to be below an efficacious dosage.

Effect of a mechanical grooming brush on the behavior and health of recently weaned heifer calves

BackgroundCalf stress at weaning and during transition to group pens represents a concern in dairy operations. Favoring natural behaviors, such as grooming, may help on reducing this challenge. Our objective was to evaluate the effect of a mechanical grooming brush on behavior and health of recently weaned calves, after transferring from individual to group housing. Two treatment groups (control [CON, n = 81]; automated brush [AB, n = 81]) were compared enrolling Holstein heifers (94 ± 7 d old) that were monitored for 20 days. Four cohorts, considering one CON and one AB group (19–20 calves/pen/cohort) were enrolled sequentially. Each calf was weighed, clinically evaluated, and affixed with a 3-D accelerometer sensor attached to the ear at enrolment. Continuous measurements (min/h) were generated for the following behaviors: Not-active, active, highly active, eating, and ruminating. Cameras for continuous video recording were installed in each pen, and calves were weighted at the last day of the study (d 20). Behavioral data were summarized as daily averages (min/h). Data was examined using repeated measures analysis for nested factors, with day as the time unit.ResultsOverall, calves had their first interaction with the brush within 2.5 days with a mean (SE) of 7 (±9.6) h after being transferred to group pens. A significant effect was determined for the interaction day by treatment on the time spent not-active and eating. Average not-active time was greater in CON compared to AB (22.8 ± 0.82 min/h vs. 21.7 ± 0.82 min/h), while eating time was greater in AB compared with CON (7.01 ± 0.40 min/h vs. 6.43 ± 0.40 min/h). Treatment groups had a similar weight gain and time to the first disease.ConclusionsWe concluded that the use of a mechanical brush influenced behavior, reducing not-active time, while increasing eating time. The consequences of this change in activity require further investigation.

Reliable identification of pregnant dairy cows by double milk progesterone analysis

In view of unsatisfactory conception rates commonly encountered in high producing dairy operations reliable ways of early pregnancy detection are of practical relevance. By analyzing the milk progesterone concentration 3 weeks after insemination non-pregnant cows can be reliably detected, whereas the accuracy of detecting pregnant cows is known to be less reliable. A field study was conducted on 25 North German dairy farms. Weekly milk samples were analyzed for progesterone content from the first to the seventh week after insemination. The accuracy of prediction of an existing pregnancy, based on a high progesterone level 3 weeks after insemination, was 80.1% as compared to palpation per rectum which served as gold standard. The prediction accuracy of samples taken at any time between 19 and 23 days after insemination was virtually similar to that of samples taken punctually on day 20 or 21. The accuracy of prediction could be substantially improved by analyzing an additional milk sample. When collecting the additional sample 1, 2, 3 or 4 weeks after the 3 week-sample, prediction accuracy was increased to 90.3%, 91.6%, 94.7% and 97.0%, respectively. Double milk progesterone analysis of samples drawn 3 and 7 weeks after insemination provides a prediction accuracy of pregnant cows comparable to that of palpation per rectum, transvaginal ultrasonography or PAG determination. The capability to reliably detect open cows in time to have them re-inseminated at the first return-estrus and, by analyzing an additional milk sample, equally reliably detect existing pregnancies, yields the milk progesterone test a valuable management tool. It will become even more attractive with the anticipated availability of practicable on-farm milk progesterone tests and access to robotic sampling equipment.

Validation of an automated cell counter to determine leukocyte differential counts in neonatal Holstein calves

Recent advances in the understanding of risk factors and biomarkers in calves entering rearing facilities show promise for identifying high-risk calves on arrival at veal and dairy beef operations. Rapid automated leukocyte differential cell counts may be a good addition for augmenting or refining calf risk identification on-farm. The objective of this study was to validate an automated leukocyte cell counter, the QScout BLD test (Advanced Animal Diagnostics, Morrisville, NC), for its ability to determine leukocyte differential cell counts in neonatal Holstein calves. From June to July 2018, blood samples collected in EDTA anticoagulant from 235 calves upon arrival at an independent veal research facility in Ontario, Canada, were evaluated using the QScout BLD test and manually by microscopy. We compared these leukocyte differential counts using Lin's concordance correlation coefficient (ρ) and found very good agreement between tests for neutrophil counts (ρ = 0.83); fair agreement for lymphocyte counts (ρ = 0.32); fair agreement for the ratio of neutrophils to lymphocytes (ρ = 0.36); slight agreement for monocyte counts (ρ = 0.14); and slight agreement for eosinophil counts (ρ = 0.20). We further examined test results to determine if they differed in their classification of samples as being above, within, or below reported 95% reference intervals for neonatal Holstein calves. Classification between tests resulted in very good agreement for neutrophils and lymphocytes, with only 4.2% and 5.8% disagreement in classification, respectively. We observed moderate agreement for monocytes, with 23.3% classified differently, and poor agreement for eosinophils, with 70.3% classified differently. Further study is required to determine the role of leukocyte profiling in the risk assessment of calves arriving at calf-rearing facilities.

Fecal Microbial Communities in a Large Representative Cohort of California Dairy Cows.

Improved sequencing and analytical techniques allow for better resolution of microbial communities; however, the agriculture field lacks an updated analysis surveying the fecal microbial populations of dairy cattle in California. This study is a large-scale survey to determine the composition of the bacterial community present in the feces of lactating dairy cattle on commercial dairy operations. For the study, 10 dairy farms across northern and central California representing a variety of feeding and management systems were enrolled. The farms represented three typical housing types including five freestall, two drylot and three pasture-based management systems. Fresh feces were collected from 15 randomly selected cows on each farm and analyzed using 16S rRNA gene amplicon sequencing. This study found that housing type, individual farm, and dietary components significantly affected the alpha diversity of the fecal microbiota. While only one Operational Taxonomic Unit (OTU) was common among all the sampled individuals, 15 bacterial families and 27 genera were shared among 95% of samples. The ratio of the families Coriobacteriaceae to Bifidobacteriaceae was significantly different between housing types and farms with pasture fed animals having a higher relative abundance of Coriobacteriaceae. A majority of samples were positive for at least one OTU assigned to Enterobacteriaceae and 31% of samples contained OTUs assigned to Campylobacter. However, the relative abundance of both taxa was <0.1%. The microbial composition displays individual farm specific signatures, but housing type plays a role. These data provide insights into the composition of the core fecal microbiota of commercial dairy cows in California and will further generate hypotheses for strategies to manipulate the microbiome of cattle.

Evolution in fixed-time: from synchronization of ovulation to improved fertility

Summary. Synchronization of ovulation and subsequent timed artificial insemination became a popular practice in modern, large scale, dairy and beef commercial operations. Popularity was because it became a serious option to eliminate a laborious and low efficiency activity in the industry: checking cows for heat. Synchronization protocols involve the sequential administration of reproductive hormones to manipulate the estrous cycle to provide a fertile oocyte for insemination at a predictable moment. In the last 20 years, great effort was put forth in protocol development and adjustment; current rates of synchronous ovulations are 80–90%. Moreover, fertility to current protocols is similar to that obtained in cows inseminated after heat detection. The present wave of protocol development proposes to face the challenge of further improving pregnancy success of current protocols. The guiding principle is that, due to the intense metabolism associated with copious milk production, steroid hormone concentrations are insufficient for adequate reproductive function. Thus, new protocols have incorporated strategies to adjust the endocrine milieu and consequently support specific portions of the synchronization process. This paper discusses the positive fertility impact of protocol design that incorporated the following concepts: controlling P4 concentrations during follicle growth to increase oocyte quality; reducing circulating P4 prior to AI to increase proportion of cows pregnant; providing estrogen priming during proestrus to benefit conception and reduce embryo mortality; and optimizing progesterone priming during early diestrus to enhance conceptus survival. It is expected that adoption of these concepts will lead to a continuous increase in fertility of lactating dairy cows.

The Role of Clustering in the Adoption of Organic Dairy: A Longitudinal Networks Analysis between 2002 and 2015

This paper uses network analysis to study the geo-localization decisions of new organic dairy farm operations in the USA between 2002 and 2015. Given a dataset of organic dairy certifications we simulated spatio-temporal networks based on the location of existing and new organic dairy farming operations. The simulations were performed with different probabilities of connecting with existing or incoming organic farmer operations, to overcome the lack of data describing actual connections between farmers. Calculated network statistics on the simulated networks included the average degree, average shortest path, closeness (centrality), clustering coefficients, and the relative size of the largest cluster, to demonstrate how the networks evolved over time. The findings revealed that new organic dairy operations cluster around existing ones, reflecting the role of networks in the conversion into organic production. The contributions of this paper are twofold. First, we contribute to the literature on clustering, information sharing, and market development in the agri-food industry by analyzing the potential implications of social networking in the development of a relatively new agriculture market. Second, we add to the literature on empirical social networks by using a new dataset with information on actors not previously studied analytically.

Production and utilization of silages in tropical areas with focus on Brazil

AbstractThis manuscript brings an overview of the current challenges, advances and opportunities for silage production and utilization in tropical areas, with particular reference to Brazil and South America. Tropical crops have a high production potential during the rainy season; therefore, silage has a central role in feed preservation in the tropics. Use of silage all‐year round is expanding, since a significant number of dairy farmers are moving from grazing to housed systems, and the number of beef cattle finished in feedlots is increasing. Whole‐plant maize silage has been by far the main conserved forage in both dairy and beef operations, whereas the use of grain silages (maize and sorghum) is increasing. Recently, there has been great interest in snaplage (mainly comprised of maize kernels, cob and husk) due to the logistic benefits. Although pull‐type forage harvesters are still common in Brazilian dairies, the majority of beef feedlots use self‐propelled foragers by hiring custom services. Hence, the number of contractors with self‐propelled harvesters has significantly increased. The convenience of a secondary high‐quality forage in diets of dairy cows as well as the opportunity of including forage sources alternative to maize silage in rations for beef cattle warrants the resumption of research on tropical grass silages. Conservation of wet by‐products, environmental aspects of silage making and, especially, silage pathogenicity and food safety are also fields of research opportunity.

Management of preweaned bull calves on dairy operations in the United States

Many calves born on dairy farms are male, but little research to date has focused on the management of these calves. The objective of this study was to survey management practices of preweaned dairy bull calves and compare these practices with those used for heifer calves on the same operations. This study was conducted as part of the USDA National Animal Health Monitoring System Dairy 2014 study and included a sample of 42 operations from 10 states. On average, 2.4% of bull calves died before leaving the operation, with most operations selling bull calves before weaning (97.6%). Bull calves left the operation at an average age of 7.6 d (median = 4 d). Producers reported that 96.3% of bull calves received colostrum. Of bulls that were fed colostrum, the vast majority (95.4%) were hand-fed; the remaining calves received colostrum via a combination of hand-feeding and suckling (3.1%) or by suckling only (1.5%). In contrast, all heifer calves on those operations were only hand-fed colostrum. On average, bull calves received 3.1 L of colostrum at their first feeding at 4.3 h after birth compared with 2.9 L at 2.9 h after birth for heifer calves. In the first 24 h, bull and heifer calves received 4.8 and 5.5 L of colostrum, respectively. Only 21.4% of operations dehorned bull calves; in comparison, heifer calves were dehorned on 90.5% of operations. Few operations used analgesics or anesthetics when dehorning bull calves, whereas 28.9% of operations used anesthetics or analgesics when dehorning heifer calves. Overall, 27.8% of operations castrated bull calves. Of the operations that did castrate bulls, 70.0% used a band at an average age of 6.3 wk; the remaining 30% of operations used a knife at 14.7 wk of age on average. Few operations used analgesics or anesthetics when castrating. These results illustrate differences in the care of bull and heifer calves and suggest the need to improve education regarding recommended colostrum feeding and pain management practices in all calves regardless of sex.

Considerations for studying transmission of antimicrobial resistant enteric bacteria between wild birds and the environment on intensive dairy and beef cattle operations.

BackgroundWild birds using livestock facilities for food and shelter may contribute to dissemination of enteric pathogens or antimicrobial resistant bacteria. However, drivers of microbial exchange among wildlife and livestock are not well characterized. Predisposition for acquiring and retaining environmental bacteria may vary among species because of physiologic or behavioral differences, complicating selection of a bacterial model that can accurately characterize microbial connections among hosts of interest. This study compares the prevalence and antibiotic resistance phenotypes of two potential model bacterial organisms isolated from wild birds and their environments.MethodsWe compared prevalence and resistance profiles of Escherichia coli and Enterococcus species isolated from environmental swabs and bird feces on a residential control site, a confinement dairy, a pasture-based beef farm, and a confinement beef farm.ResultsBird feces at all sites had low-to-moderate prevalence of Escherichia coli (range: 17–47%), despite potential for exposure on farms (range: 63–97%). Few Escherichia coli were isolated from the control environment. Enterococcus faecalis was dominant in birds at both beef farms (62% and 81% of Enterococcus isolates) and low-to-moderately prevalent at the dairy and control sites (29% and 23% of isolates, respectively). Antimicrobial resistance prevalence was higher in farm samples compared to those from the residential control, but distribution of resistant isolates varied between the bacterial genera. Birds on all farms carried resistant Enterococcus at similar rates to that of the environment, but resistance was less common in bird-associated Escherichia coli despite presence of resistant isolates in the farm environment.DiscussionBacterial species studied may affect how readily bacterial exchange among populations is detected. Selection of microbial models must carefully consider both the questions being posed and how findings might influence resulting management decisions.

Prediction of human assessments of dairy odor utilizing a fast gas chromatograph and neural networks

A method based on hedonic tone was developed and applied to evaluate human assessments of odor emitted from dairy operations using a fast gas chromatograph and neural networks. A general pleasantness scale ranging from −11 (extremely unpleasant) to +11 (extremely pleasant) was used to collect human responses. The panelists were able to identify the difference between various samples, and gave individually consistent responses for the same sample. The measurements of a fast gas chromatograph, called the zNose, were trained using Artificial Neural Networks (ANNs) to predict the human assessments. Three ANNs, Levenberg-Marquardt Back-propagation Neural Network (LMBNN), Scaled Conjugate Gradient Back-propagation (CGBNN), and Resilient Back-propagation Neural Network (RPBNN), were applied to connect human assessments and instrument measurements. In separate validation, zNose-LMBNN model showed superiority in four criteria, Mean Square Error (MSE), Correlation Coefficient (R), probability within 10% range to target, and probability within 5% range to target. The optimal model outputs represented human response as high as 67% within the 10% range and 44% within the 5% range of the targets. In addition, the model outputs have a good linear relationship with the targets (R = 0.53).

A preliminary evaluation of veterinary antibiotics, estrogens, in vitro estrogenic activity and microbial communities in airborne particulate matter collected near dairy production facilities

Particulate matter (PM) emitted from beef cattle feedyards transports manure-affiliated compounds including antibiotics and steroids from feedyards into the surrounding environment. Similarly, commercial dairy operations have the potential to release PM, comprised largely of aerosolized manure, into the surrounding environment along with associated veterinary antibiotics and steroids. The goal of this study was to quantify and compare total suspended particulates, antibiotics and estrogens collected upwind and downwind of dairies in the Southern High Plains, and to characterize microbial community structure and in vitro estrogenic activity of collected PM. PM collected downwind of dairies had greater microbial diversity (as measured by number of operational taxonomic units) and had greater frequencies of detection for antibiotics and estrogens than associated upwind PM. Dominant bacterial phyla and overall microbial community composition were similar among upwind and downwind PM, and extracts of upwind and downwind PM produced no in vitro estrogenic activity. Although this study surveyed a limited number of dairies in the region, these results suggest that dairy operations in the Southern High Plains, in contrast to feedyards, appear to be minor contributors of total aerial PM and associated antibiotics and steroids to the terrestrial environment.

Genomic evaluation for calf wellness traits in Holstein cattle

Reducing calf morbidity and mortality is important for attaining financial sustainability and improving animal welfare on commercial dairy operations. Zoetis (Kalamazoo, MI) has developed genomic predictions for calf wellness traits in Holsteins that include calf respiratory disease (RESP; recorded between 0 and 365 d of age), calf scours (DIAR; recorded between 2 and 50 d of age), and calf livability (DEAD; recorded between 2 and 365 d of age). Phenotype and pedigree data were from commercial dairies and provided directly by producers upon obtaining their permission. The number of records ranged from 741,484 for DIAR to 1,926,261 for DEAD. The number of genotyped animals was 325,025. All traits were analyzed using a univariate threshold animal model including fixed effect of year of birth × calving season × region, and random effects of herd × year of birth and animal. A total of 45,425 SNP were used in genomic analyses. Animals genotyped with low-density chips were imputed to the required number of SNP. All analyses were conducted using single-step genomic BLUP implementing the "algorithm for proven and young" (APY) animals designed to accommodate very large numbers of genotypes. Estimated heritabilities were 0.042, 0.045, and 0.060 for RESP, DIAR, and DEAD, respectively. The genomic predicted transmitting abilities ranged between -8.0 and 24.0, -11.5 and 28.5, and -6.5 to 22.8 for RESP, DIAR, and DEAD, respectively. Reliabilities of breeding values were obtained by approximation based on partitioning of a function of reliability into contributions from records, pedigree, and genotypes, where the genotype contribution was approximated using the diagonal value of the genomic relationship matrix. The average reliabilities for the genotyped animals were 41.9, 42.6, and 47.3% for RESP, DIAR, and DEAD, respectively. Estimated genomic predicted transmitting abilities and reliabilities were approximately normally distributed for all analyzed traits. Approximated genetic correlations of calf wellness with Zoetis dairy wellness traits and traits included in the US national genetic evaluation were low to moderate. The results indicate that direct evaluation of calf wellness traits under a genomic threshold model is feasible and offers predictions with average reliabilities comparable to other lowly heritable traits. Genetic selection for calf wellness traits presents a compelling opportunity for dairy producers to help manage herd replacement costs and improve overall profitability.