The objective of this clinical trial was to evaluate the effectiveness of zinc supplementation on diarrhea and average daily weight gain (ADG) in pre-weaned dairy calves. A total of 1,482 healthy ...Holstein heifer and bull calves from a large California dairy were enrolled at 24 to 48 hours of age until hutch exit at approximately 90 days of age. Calves were block-randomized by time to one of three treatments: 1) placebo, 2) zinc methionine (ZM), or 3) zinc sulfate (ZS) administered in milk once daily for 14 days. Serum total protein at enrollment and body weight at birth, treatment end, and hutch exit were measured. Fecal consistency was assessed daily for 28 days post-enrollment. For a random sample of 127 calves, serum zinc concentrations before and after treatment and a fecal antigen ELISA at diarrhea start and resolution for Escherichia coli K99, rotavirus, coronavirus, and Cryptosporidium parvum were performed. Linear regression showed that ZM-treated bull calves had 22 g increased ADG compared to placebo-treated bulls (P = 0.042). ZM-treated heifers had 9 g decreased ADG compared to placebo-treated heifers (P = 0.037), after adjusting for average birth weight. Sex-stratified models showed that high birth weight heifers treated with ZM gained more than placebo-treated heifers of the same birth weight, which suggests a dose-response effect rather than a true sex-specific effect of ZM on ADG. Cox regression showed that ZM and ZS-treated calves had a 14.7% (P = 0.015) and 13.9% (P = 0.022) reduced hazard of diarrhea, respectively, compared to placebo-treated calves. Calves supplemented for at least the first five days of diarrhea with ZM and ZS had a 21.4% (P = 0.027) and 13.0% (P = 0.040) increased hazard of cure from diarrhea, respectively, compared to placebo-treated calves. Logistic regression showed that the odds of microbiological cure at diarrhea resolution for rotavirus, C. parvum, or any single fecal pathogen was not different between treatment groups. Zinc supplementation delayed diarrhea and expedited diarrhea recovery in pre-weaned calves. Additionally, zinc improved weight gain differentially in bulls compared to heifers, indicating a research need for sex-specific dosing.
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Stable flies (Stomoxys calcitrans) are blood-sucking insects commonly associated with cattle production systems worldwide and are known to cause severe irritation to cattle due to painful bites. ...Cattle react to biting stable flies with an aggregating behavior known as bunching. Bunching behavior reduces grazing or feed consumption and thus reduces cattle productivity and welfare. Cattle's fly-repelling behaviors include foot stomping, head tossing, tail switching and skin twitching. A longitudinal study was conducted in 2017 on 20 California dairies (average lactating herd size = 2,466 (SE±28.392)) during the stable fly season from April to July. The study objectives were to estimate the association between environmental factors and dairy characteristics including facility design, feed and manure management, total mixed ration (TMR) components fed to cattle, and operational pest management procedures and the outcome stable fly activity on California dairies. Stable fly activity was measured by counting stable flies on cow forelimbs (leg count) and on Alsynite traps (trap count) over the 13-week study period. Weekly leg counts were performed for cattle in lactating cow pens (31 pens from 10 study dairies) with counts made during the morning (AM) and again during the afternoon (PM). Trap counts were performed on all 20 study dairies. Data were analyzed using linear mixed models which revealed temporal variation in the average leg and trap counts with stable fly activity increasing from May to June and then decreasing to the lowest activity in July. Leg counts were higher during the afternoon compared to morning. Ambient temperatures less than or equal to30â°C and relative humidity (RH) measurements <50% were associated with higher leg and trap counts. Traps located at the periphery of study dairies had higher stable fly counts compared to traps located in the interior of the dairy. Cow pens with trees on the periphery had higher leg counts in comparison to pens away from trees. Specific TMR components were associated with both leg and trap counts. Dairies feeding by-products including almond hulls, wet distillers' grain, fruits, and vegetables had higher trap counts compared to dairies that did not feed these ingredients. At the pen level, pens with rations that contained straw had lower average leg counts compared to pens fed with rations that did not contain straw. A similar association was observed for pens with rations that contained wheat silage when ambient temperatures were less than or equal to30â°C. In contrast, pens with water added to the TMR while the RH was greater than or equal to50% had higher average leg counts compared to pens without water added to the TMR. Dairies that applied insecticides for fly control to their entire facility had lower trap counts compared to dairies that did not apply insecticides. Stable fly activity measured on California dairies using leg and trap counts varied according to the month, environmental factors, pen surroundings, trap location, TMR components, and insecticide use.
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Bunching is the term used to describe the protective aggregating behavior of cattle against the painful bites of stable flies (Stomoxys calcitrans), where cattle gather in a group with their heads to ...the center of the group and their tails to the outside to reduce stable fly attack. Both sexes of the stable fly feed on blood, and their painful bites negatively impact cattle health, productivity and welfare. A longitudinal study was conducted from April to July 2017 to estimate the stable fly activity on 20 California dairies (average herd size = 2466 ± 1050), to determine stable fly activity that induced bunching, and to evaluate the association between management and environmental factors, and cattle bunching. Stable fly activity was recorded weekly using trap counts and leg counts. Data was analyzed using linear mixed models with odds ratio. Cattle bunching at the dairy level was predicted by mean trap counts of ≥150 flies/trap/week, while bunching at the pen level was predicted by mean leg counts >1 fly/leg/cow or mean trap counts >50 flies/trap/week for traps closest to the pen. Additional risk factors predicting cattle bunching at the dairy level were study week (May/June vs July), presence of crops adjacent to dairy >2 sides, and feeding wet distillers grain. Additional risk factors predicting cattle bunching at the pen level were study week (May/June vs July), ambient temperature ≤30°C, pen design (freestall vs open dry lot or bedded pack), production status (lactating/dry vs close-up), presence of crops surrounding cattle pens, feeding rations containing molasses. Cattle bunching was reduced at the pen level by relative humidity >50%, and when the cattle pen was surrounded by other cattle pens or was bordered by a main road. At the dairy level, removal of manure along fence lines of cattle pens was protective against cattle bunching.
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The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes.
Most US dairy calves are raised in individual hutches ...for biocontainment purposes and to facilitate monitoring and handling of calves. However, individual hutches typically restrict calves' activity and social interactions. Previous studies showed that group housing (GH) is beneficial to calf welfare and is associated with social benefits. The adoption of GH on dairies is hindered by several concerns, with the primary concern being the potential for increased transmission of diseases due to heightened calf-to-calf contact. In light of this, our study aimed to compare the behavior, health, and growth outcomes of calves housed in groups of 3 to individually housed (IH) calves during the preweaning period. A total of 42 Holstein heifer calves on a commercial dairy in Northern California were enrolled in groups of 3 to different housing treatments; IH (n = 21) or GH (n = 21) between July and October 2020. Each treatment was composed of 7 groups of 3 calves each. Calves in the GH treatment were housed in groups of 3 from 6 to 10 d until 70 d of age. Individual pens consisted of one polyethylene hutch with a 1.5 m × 1.2 m outside exercise area. Group pens were constructed by assembling 3 polyethylene hutches with a 1.5 m × 3.6 m outside exercise area of wire panel fencing. Calves were weighed and measured for height at birth and weaning. Diarrhea and bovine respiratory disease (BRD) scores were recorded daily throughout the preweaning period. Cumulative incidence and hazard ratios were estimated for BRD and diarrhea for GH and IH. A mixed model with pen as a random effect was specified to evaluate the effect of treatment. Group-housed calves gained 0.64 ± 0.02 kg/d while IH calves gained 0.65 ± 0.02 kg/d. Similarly, there was no evidence for treatment differences in withers height gain in GH calves (0.22 ± 0.01 cm/d) compared with IH calves (0.21 ± 0.01 cm/d). The cumulative incidence of BRD based on the California scoring system in GH calves was 75 ± 9.68% compared with 66.66 ± 10.28% in IH calves. Group-housed calves had a BRD hazard of 1.14 times that of IH calves (95% CI: 1.21–2.40). The cumulative incidence of diarrhea (fecal score 3) in GH calves was 100% in comparison to 95.20% ± 4.66% in IH calves. The mean proportion of scan observations of calves feeding on concentrates was significantly higher in GH (0.145 ± 0.004/h) compared with IH calves (0.076 ± 0.003/h) during the preweaning period. The study results provide evidence that this simplified GH system provides benefits of GH without detrimental short-term effects on calf growth and health during the preweaning period.
Microbiota play important roles in the gastrointestinal tract (GIT) of dairy cattle as the communities are responsible for host health, growth, and production performance. However, a systematic ...characterization and comparison of microbial communities in the GIT of cattle housed in different management units on a modern dairy farm are still lacking. We used 16S rRNA gene sequencing to evaluate the fecal bacterial communities of 90 dairy cattle housed in 12 distinctly defined management units on a modern dairy farm.
We found that cattle from management units 5, 6, 8, and 9 had similar bacterial communities while the other units showed varying levels of differences. Hutch calves had a dramatically different bacterial community than adult cattle, with at least 10 genera exclusively detected in their samples but not in non-neonatal cattle. Moreover, we compared fecal bacteria of cattle from every pair of the management units and detailed the number and relative abundance of the significantly differential genera. Lastly, we identified 181 pairs of strongly correlated taxa in the community, showing possible synergistic or antagonistic relationships.
This study assesses the fecal microbiota of cattle from 12 distinctly defined management units along the production line on a California dairy farm. The results highlight the similarities and differences of fecal microbiota between cattle from each pair of the management units. Especially, the data indicate that the newborn calves host very different gut bacterial communities than non-neonatal cattle, while non-neonatal cattle adopt one of the two distinct types of gut bacterial communities with subtle differences among the management units. The gut microbial communities of dairy cattle change dramatically in bacterial abundances at different taxonomic levels along the production line. The findings provide a reference for research and practice in modern dairy farm management.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This study proposes a new methodology to analyze the impacts of host and pathogen dispersal on coinfection dynamics using the example of Escherichia coli O157:H7 in a dairy farm. A multi-strain ...Susceptible–Infected–Susceptible model is extended to a Reaction–Diffusion (RD) coinfection model of E. coli O157:H7 transmission, which includes intermittent shedding and pathogen growth in the environment. Analysis of the new RD coinfection model consists of existence and stability of constant equilibria, calculation of the basic reproduction number, and existence of traveling and stationary wave solutions. A stationary wave solution of the RD model defines a nonconstant endemic equilibrium. Whereas a traveling wavefront represents an epidemic wave of infection passing through the farm with a specific speed, direction, and amplitude. The numerical simulations of the RD model demonstrate stable traveling and stationary wavefronts of the RD coinfection model. The stationary wavefront connects two constant coexistence equilibria and the traveling wavefront represents the gradual establishment of an endemic coexistence equilibrium in the dairy farm. The significance of this study lies in utilizing the nonlinear wave theory to analyze dynamics of coinfection in a dairy farm both with respect to location and time. Hence, in addition to Turing theory, the nonlinear wave theory can be used to determine the likelihood of acquiring the infection based on the location of cattle at each specific time.
•We investigate the impacts of dispersal on coinfection dynamics of E. coli using an RD model.•Conditions for existence and stability of wave and constant solutions are established.•The wave solutions of the RD model simulate the spread and dominance of different E. coli strains.•Shedding longevity may offer a survival mechanism to weaker E. coli strains.•Rich dynamics of the RD model can unpack complex dynamics of the host-pathogen system.
The objective of this study was to evaluate the impact of dietary zinc supplementation in pre-weaned dairy calves on the phenotypic antimicrobial resistance (AMR) of fecal commensal bacteria. A ...repository of fecal specimens from a random sample of calves block-randomized into placebo (n = 39) and zinc sulfate (n = 28) groups collected over a zinc supplementation clinical trial at the onset of calf diarrhea, calf diarrheal cure, and the last day of 14 cumulative days of zinc or placebo treatment were analyzed. Antimicrobial susceptibility testing was conducted for Enterococcus spp. (n = 167) and E. coli (n = 44), with one representative isolate of each commensal bacteria tested per sample. Parametric survival interval regression models were constructed to evaluate the association between zinc treatment and phenotypic AMR, with exponentiated accelerated failure time (AFT) coefficients adapted for MIC instead of time representing the degree of change in AMR (MIC Ratio, MR). Findings from our study indicated that zinc supplementation did not significantly alter the MIC in Enterococcus spp. for 13 drugs: gentamicin, vancomycin, ciprofloxacin, erythromycin, penicillin, nitrofurantoin, linezolid, quinupristin/dalfopristin, tylosin tartrate, streptomycin, daptomycin, chloramphenicol, and tigecycline (MR = 0.96-2.94, p > 0.05). In E. coli, zinc supplementation was not associated with resistance to azithromycin (MR = 0.80, p > 0.05) and ceftriaxone (MR = 0.95, p > 0.05). However, a significant reduction in E. coli MIC values was observed for ciprofloxacin (MR = 0.17, 95% CI 0.03-0.97) and nalidixic acid (MR = 0.28, 95% CI 0.15-0.53) for zinc-treated compared to placebo-treated calves. Alongside predictions of MIC values generated from these 17 AFT models, findings from this study corroborate the influence of age and antimicrobial exposure on phenotypic AMR.
Our objectives were to evaluate the diagnostic accuracy of a rapid and novel immunochromatography-based mastitis kit that includes 3 independent tests to detect coliforms (Escherichia coli or ...Klebsiella pneumoniae), Streptococcus spp., and Staphylococcus aureus. The kit was developed to facilitate diagnostic-based mastitis treatment. Validation of the kit was based on 154 aseptically collected mastitis samples from 2 clinical herds (clinical population) and 120 milk samples from 3 nonclinical herds (nonclinical population) without clinical cases at the time of enrollment. One herd sampled at different times was common to both populations. A 3-test in 2-population Bayesian latent class model with uniform priors for all test parameters except specificity of culture, which was modeled informatively, was used to estimate sensitivity (Se) and specificity (Sp) of the test kit, culture, and PCR at the cow level. The mastitis test kit's 96.9% Sp for Streptococcus spp. had a low false positive percentage (3.1%), which, together with the kit's rapid turnaround time for results, makes it a suitable initial screening test that producers can use to identify clinical cows to treat based on Streptococcus spp. mastitis in kit-positive results. Due to the 60.4% kit Se, producers should follow up on Streptococcus spp. kit-negative cows using a confirmatory test such as PCR (Sp of 98.4%) or culture (Sp of 99.6%). In contrast, aerobic culture had Se of 76.5% and Sp of 99.6% for Streptococcus spp. Similarly, the Sp of the kit (98.2%) and culture (99.8%) for Staph. aureus were particularly high, and even though the kit's Se (61.0%) was lower than culture (88.4%; posterior probability of difference 98%), the kit could be beneficial before use of a confirmatory test for kit-negative samples due to its ease and rapid turnaround time. Mostly, quantitative real-time (q)PCR outperformed the kit's Se (37.7%) and Sp (92.9%) for coliforms, as well as the kit's Se (60.4%) for Streptococcus spp. However, qPCR may require more technical skills and turnaround time for final results. Use of the on-farm mastitis test kit evaluated in the present study could enhance sustainable antimicrobial drug use by rapidly identifying Streptococcus mastitis for targeted treatment. Furthermore, the kit may be used in a Staph. aureus outbreak where cows can be rapidly screened to identify cases for segregation or culling during an outbreak and kit-negative cows further confirmed by milk culture or qPCR. However, the cost-effectiveness of such an approach has not been investigated.
...crossing implies that the AM bunching observations completed at the same morning on all the pens in all the dairies. https://doi.org/10.1371/journal.pone.0235775.g001 thumbnail Download: * PPT ...PowerPoint slide * PNG larger image * TIFF original image Fig 3. The upper and lower horizontal lines of the box represent the 25th and 75th percentiles respectively, the horizontal midline represents the median, the upper and lower horizontal whiskers lines are the upper and lower limits and the dots are the outliers. https://doi.org/10.1371/journal.pone.0235775.g002 thumbnail Download: * PPT PowerPoint slide * PNG larger image * TIFF original image Fig 4. The upper and lower horizontal lines of the box represent the 25th and 75th percentiles respectively, the horizontal midline represents the median, the upper and lower horizontal whiskers lines are the upper and lower limits and the dots are the outliers. https://doi.org/10.1371/journal.pone.0235775.g003 thumbnail Download: * PPT PowerPoint slide * PNG larger image * TIFF original image Fig 5. The upper and lower horizontal lines of the box represent the 25th and 75th percentiles respectively, the horizontal midline represents the median, the upper and lower horizontal whiskers lines are the upper and lower limits and the dots are the outliers. https://doi.org/10.1371/journal.pone.0235775.g004 thumbnail Download: * PPT PowerPoint slide * PNG larger image * TIFF original image Fig 6. El Ashmawy WR, Williams DR, Gerry AC, Champagne JD, Lehenbauer TW, Aly SS (2019) Risk factors affecting dairy cattle protective grouping behavior, commonly known as bunching, against Stomoxys calcitrans (L.) on California dairies.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Antibiotic resistance genes (ARGs) are emerging contaminants causing serious global health concern. Interventions to address this concern include improving our understanding of methods for treating ...waste material of human and animal origin that are known to harbor ARGs. Anaerobic digestion is a commonly used process for treating dairy manure, and although effective in reducing ARGs, its mechanism of action is not clear. In this study, we used three ARGs to conducted a longitudinal bench scale anaerobic digestion experiment with various temperatures (28, 36, 44, and 52°C) in triplicate using fresh dairy manure for 30 days to evaluate the reduction of gene abundance. Three ARGs and two mobile genetic elements (MGEs) were studied: sulfonamide resistance gene (sulII), tetracycline resistance genes (tetW), macrolide-lincosamide-streptogramin B (MLSB) superfamily resistance genes (ermF), class 1 integrase gene (intI1), and transposase gene (tnpA). Genes were quantified by real-time quantitative PCR. Results show that the thermophilic anaerobic digestion (52°C) significantly reduced (p < 0.05) the absolute abundance of sulII (95%), intI1 (95%), tnpA (77%) and 16S rRNA gene (76%) after 30 days of digestion. A modified Collins-Selleck model was used to fit the decay curve, and results suggest that the gene reduction during the startup phase of anaerobic digestion (first 5 days) was faster than the later stage, and reductions in the first five days were more than 50% for most genes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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