Effect of a dairy farmworker stewardship training program on antimicrobial drug usage in dairy cows.

Antimicrobial use (AMU) is critical to preserving animal health and welfare. However, the development of antimicrobial resistance (AMR) represents a public health threat. Although most antimicrobials used on the farm require a veterinarian prescription, farmworkers make daily on-farm treatment decisions. Therefore, farmworker training is vital to promote responsible AMU. This research project aimed to evaluate the effect of farmworker antimicrobial stewardship (AMS) training on the quantity of AMU on dairy farms in Ohio and California. We hypothesized that farms receiving AMS training would have reduced AMU in dairy cattle compared with farms where training wasn't administered. We designed a quasiexperimental study with 18 conventional dairy farms enrolled in Ohio and California. Twelve farms received AMS training, and 6 farms did not. The AMS program included a 12-wk training focused on accurate identification of cows requiring antimicrobial treatment. We quantified AMU by collecting used drug containers, manually counted by researchers during farm visits. Treatment incidence (TI) was calculated using animal daily doses (ADD), and Poisson regression models were used to analyze the TI data. Disease incidence rate (DIR) in lactating cows was 2.2, 1.5, 1.0, 0.4, 0.3, 0.2, and 0.03/1,000 cow-days for mastitis, lameness, metritis, pneumonia, retained placenta, diarrheas, and other diseases (e.g., conjunctivitis, injuries), respectively. The highest TI by antimicrobial class (provided in ADD/1,000 cow-days) was cephalosporin (5.9), penicillin (5.2), tetracyclines (0.4), lincosamides (0.2), and sulfonamides (0.1). Among the trained farms using a within-treatment group analysis, no significant differences were observed in TI pre-intervention (10.9 ADD/1,000 cow-days) compared with TI postintervention (10.3 ADD/1,000 cow-days). Treatment incidence from the training group was 10.8 ADD/1,000 cow-days and although numerically lower, it was not significantly different compared with TI in the control groups at 13.9 ADD/1,000 cow-days (rate ratio = 0.77, CI = 0.25-2.38). Future research on AMS should incorporate farmworker training with social science approaches to overcome barriers and promote on-farm responsible use.

Characterization of controlled trials on probiotic supplementation to dairy calves: A scoping review.

The objective of this scoping review was to identify, describe, and characterize the literature on probiotic supplementation in dairy calves. Eligible studies were nonrandomized, quasi-randomized and randomized controlled trials in English, Spanish, or Portuguese that evaluated the effect of probiotic supplementation on growth and health of dairy calves. The search strategies were based on a modification of the PICO (Population, Intervention, Comparator, Outcome) framework and used synonyms and words related to "dairy calves" (population), "probiotics" (intervention), and "growth and health measurements" (outcomes). No restrictions for publication year or language were applied. Searches were conducted in Biosis, CAB Abstracts, Medline, Scopus, and the Dissertations and Theses Database. In total, the search identified 4,467 records, of which 103 studies (110 controlled trials) met the inclusion criteria. The studies were published between 1980 and 2021 and originated from 28 countries. Trials were randomized (80.0%), nonrandomized (16.4%), and quasi-randomized (3.6%), ranging in sample size from 5 to 1,801 dairy calves (mode = 24; average = 64). Enrolled calves were frequently Holstein (74.5%), males (43.6%), and younger than 15 d at the beginning of probiotic supplementation (71.8%). Often, trials were conducted in research facilities (47.3%). Trials evaluated probiotics with single or multiple species of the same genus: Lactobacillus (26.4%), Saccharomyces (15.4%), Bacillus (10.0%), Enterococcus (3.6%), or multiple species of various genera (31.8%). Eight trials did not report the probiotic species used. Lactobacillus acidophilus and Enterococcus faecium were the species most supplemented to calves. The duration of probiotic supplementation ranged from 1 to 462 d (mode = 56; average = 50). In trials with a constant dose, it ranged from 4.0 × 106 to 3.7 × 1011 cfu/calf per day. Most probiotics were administered mixed solely into feed (88.5%; whole milk, milk replacer, starter, or total mixed ration) and less frequently orally as a drench or oral paste (7.9%). Most trials evaluated weight gain (88.2%) as a growth indicator and fecal consistency score (64.5%) as a health indicator. Our scoping review summarizes the breadth of controlled trials evaluating probiotic supplementation in dairy calves. Differences in intervention design (mode of probiotic administration, dose, and duration of probiotic supplementation) and outcomes evaluation (type and methods) justify future efforts toward standardized guidelines in clinical trials.

First-milking colostrum mineral concentrations and yields: Comparison to second milking and associations with serum mineral concentrations, parity, and yield in multiparous Jersey cows.

This observational study described first-milking colostrum mineral concentrations and total yields, and evaluated its associations with cow serum mineral concentrations, parity, and first postpartum milking yield in 100 multiparous Jersey cows from a single herd fed a negative dietary cation-anion difference diet prepartum. Additionally, first- and second-milking colostrum mineral concentrations and total yields were compared in a subset of 65 cows. Serum minerals (Ca, P, Mg, Na, K, Zn, Fe, Cu) were assessed before first milking. Cows were milked at 9 h and 4 min ± 3 h and 32 min and at 21 h and 11 min ± 3 h and 43 min postpartum (± standard deviation); yields were recorded and samples collected for mineral concentrations assessment (Ca, P, Mg, Na, K, Zn, Fe, Cu). Linear regression was used to evaluate the associations between first-milking colostrum mineral concentrations and total yields and cows' serum mineral concentrations, parity, first-milking colostrum yield, and calving-to-milking interval. The most abundant minerals in first-milking colostrum were (least squares mean ± standard error of the mean) Ca (55.71 ± 13.52 mmol/L; 8.75 ± 5.74 g) and P (41.91 ± 13.01 mmol/L; 5.26 ± 3.72 g), followed by Na (39.65 ± 13.23 mmol/L; 3.08 ± 1.77 g), K (36.47 ± 7.57 mmol/L; 5.79 ± 4.20 g), Mg (13.43 ± 3.09 mmol/L; 1.25 ± 0.78 g), Zn (272.12 ± 113.34 µmol/L; 71.98 ± 55.34 mg), Fe (12.51 ± 3.79 µmol/L; 2.56 ± 1.55 mg), and Cu (3.34 ± 1.22 µmol/L; 0.77 ± 0.56 mg). Higher concentrations of Ca, Mg, Na, Zn, Fe, and Cu, and total yields of Mg, Zn, Fe, and Cu were observed at first- compared with second-milking colostrum. Serum and first-milking colostrum Cu concentrations were positively associated, but no significant associations were observed between other minerals' serum and first-milking colostrum concentrations or total yields. Parity was associated with first-milking colostrum Ca, P, K, and Fe concentrations and yields; younger multiparous cows had higher concentrations and total yields of these minerals. Linear (Fe), quadratic (P, Na, and K), and cubic (Mg, Zn, and Cu) associations were observed between first-milking colostrum mineral concentrations and yield. In all cases, mineral total yields were linearly associated with first-milking colostrum yield. In conclusion, variation in first-milking colostrum mineral concentrations and total yields across cows could be partially explained by cow parity and colostrum yield. Further research including primiparous and cows under different management settings is needed to expand the knowledge and understanding of colostrum mineral concentrations and total yields in dairy cows.

Effects of postpartum milking strategy on plasma mineral concentrations and colostrum, transition milk, and milk yield and composition in multiparous dairy cows.

The effects of postpartum milking strategy on plasma mineral concentrations, blood ß-hydroxybutyrate (BHB) concentration, and colostrum, transition milk, and first monthly test milk yield and composition were evaluated in 90 multiparous Jersey and Jersey × Holstein crossbreed cows from a commercial farm. Before first postpartum milking, cows were randomly assigned to the following milking strategies, implemented during the first 2 d postpartum: twice-a-day milking (M2, standard industry practice, milking every 12 h; n = 22), once-a-day milking (M1, milking every 24 h; n = 24), restricted milking (MR, 3-L milking every 12 h; n = 21), and delayed milking (MD, no milking for the first 24 h, and milking every 12 h afterward; n = 23). Blood samples for total plasma Ca, P, and Mg determination were collected from enrollment every 4 h up to 48 h, and at 3 d in milk. Blood BHB concentration was determined at 3 and 11 d in milk. Colostrum and transition milk yields were recorded, and samples were collected at each study milking for IgG and somatic cell count (SCC) determinations. Information for first monthly test milk yield and composition was obtained from the Dairy Herd Improvement Association. Statistical analyses were conducted using generalized multiple linear and Poisson regressions with Dunnett adjustment and M2 as reference group for mean comparisons. Overall, plasma Ca concentration within 48 h after enrollment was higher for MD (2.17 mmol/L), tended to be higher for MR (2.15 mmol/L), and was similar for M1 (2.09 mmol/L) compared with M2 cows (2.06 mmol/L). No statistically significant differences compared with M2 cows were observed for plasma P and Mg concentrations. Colostrum and transition milk and total Ca harvested within 48 h after enrollment were lower for M1, MR, and MD compared with M2 cows. The MD strategy prevented harvesting colostrum with >50 g of IgG/L. No statistically significant effects were detected on plasma mineral concentrations at 3 DIM, blood BHB concentration, colostrum and transition milk SCC within 48 h after enrollment, or milk yield, energy-corrected milk yield, and SCC at first monthly test. Our results suggest that postpartum plasma Ca concentration may be influenced by postpartum milking strategy, without interfering with future milk yield and udder health. Further studies should evaluate whether the proposed milking strategies in early postpartum affect production, reproduction, or health.

Perspective of dairy producers from California, Idaho, South Dakota, and Washington: Health and business implications of the COVID-19 pandemic during the second wave.

The aim of this study was to document California, Idaho, South Dakota, and Washington dairy producers' perspectives on the health and business implications of COVID-19 during the pandemic second wave. Dairy producers were reached by a 14-question anonymous mail survey during June and July of 2020. We obtained 226 responses (response rate: 9.3% CA, 8.6% ID, 31.4%, and 10.0% WA). Responses were grouped by state (CA: 48.7%, ID: 15.9%, SD: 21.7%, or WA: 13.7%) and dairy size [based on number of cows; small (<100): 14.1%, medium (100-499): 27.7%, medium-large (500-1,999): 33.2%, or large (≥2,000): 25.0%]. Survey responses were summarized, and multiple correspondence analysis was used to map responses and identify data clusters. At the time of the survey, some respondents suspected (3%) or had confirmed (9%) COVID-19 cases on their premises. Respondents were somewhat or very concerned about the health (75%) and business (92%) implications associated with COVID-19. Producers were concerned about the health of their families, employees, and employees' families; having to reduce production; workforce shortage; limited goods availability; and lack of services. Producers perceived that their employees were somewhat or very concerned (74%) with the pandemic. There was COVID-19 safety information or training provided (78%) or intended (4%) in English (22%), Spanish (23%), or both (55%). The focus of training was as follows: how to remain healthy at work (91%) and at home (60%), what to do if a worker gets sick (77%), and sick leave information (54%). Nevertheless, 18% of the respondents answered that training was not going to be provided. The following control measures implemented: providing hand sanitizer or disinfectant wipes (78%), instruction on frequent hand-washing (76%), social distancing (59%), prevention of employee gatherings (54%), providing and requiring the use of face masks (49%), and limiting on-farm visitors (44%). Multiple correspondence analysis showed that concern with health risk and business impact of the COVID-19 pandemic, as well as mitigation and response strategies implemented, varied based on respondent's dairy size and state. The greatest concerns were reported by producers from California and large and medium-large dairies, whereas the fewest concerns were reported by producers from small dairies. Results from this survey highlighted the health and business concerns of dairy producers from California, Idaho, South Dakota, and Washington during the COVID-19 pandemic and the mitigation efforts adopted. In conclusion, mitigation measures were adopted by most dairy producers but in various degrees. Dairy industry service providers and educators were secondary educational resources during the pandemic; thus, future efforts toward centralized access to dairy specific bilingual educational materials are suggested.

Treatment practices after calving-related events on 45 dairy farms in California.

Retained fetal membranes (RFM), dystocia, and twinning are common postpartum events that increase the risk of metritis, impair reproductive performance, and contribute to antimicrobial use on dairies. The overall objective of this study was to describe treatment decisions after RFM, severe dystocia (cesarean section and fetotomy), nonsevere dystocia (nonmechanical and mechanical assistance to extract the calf), and twinning. A total of 44 dairies from California's San Joaquin Valley (39 Holstein and 6 Jersey or crossbreed herds) with 450 to 9,500 lactating cows were enrolled in this study. Researchers visited each dairy once to observe cow-side fresh cow health evaluations and to interview health evaluators and maternity workers, using a standardized survey tool. The survey included questions about antimicrobial (class, dose, and duration) and nonantimicrobial therapies for calving-related events. Antimicrobial therapy was used in all 44 dairies to treat RFM at 24 (n = 23), 48 (n = 10), or 72 h (n = 5) after calving, or when puerperal metritis signs were observed (n = 6). Antimicrobial therapy was used after all severe dystocia cases, and after nonsevere dystocia (n = 27) and twinning (n = 15). Ceftiofur products were the most common antimicrobial class; they were used to treat RFM cases (n = 29), nonsevere dystocia (n = 13), and twinning (n = 10). Supportive therapy for calving-related events included nonantimicrobial intrauterine treatments, nonsteroidal antiinflammatory drugs, oxytocin, i.v. calcium, or oral drenches. Our study highlights opportunities to reduce extra-label use of antimicrobials in postpartum cows affected with RFM, and the need for education and outreach efforts on judicious use of antimicrobials. Furthermore, antimicrobial treatment choices differed largely across dairies, indicating a need to reach consensus and promote standardized practices within the industry.

Integration of statistical inferences and machine learning algorithms for prediction of metritis cure in dairy cows.

The study's objectives were to identify cow-level and environmental factors associated with metritis cure to predict metritis cure using traditional statistics and machine learning algorithms. The data set used was from a previous study comparing the efficacy of different therapies and self-cure for metritis. Metritis was defined as fetid, watery, reddish-brownish discharge, with or without fever. Cure was defined as an absence of metritis signs 12 d after diagnosis. Cows were randomly allocated to receive a subcutaneous injection of 6.6 mg/kg of ceftiofur crystalline-free acid (Excede, Zoetis) at the day of diagnosis and 3 d later (n = 275); and no treatment at the time of metritis diagnosis (n = 275). The variables days in milk (DIM) at metritis diagnosis, treatment, season of the metritis diagnosis, month of metritis diagnostic, number of lactation, parity, calving score, dystocia, retained fetal membranes, body condition score at d 5 postpartum, vulvovaginal laceration score, the rectal temperature at the metritis diagnosis, fever at diagnosis, milk production from the day before to metritis diagnosis, and milk production slope up to 5, 7, and 9 DIM were offered to univariate logistic regression. Variables included in the multivariable logistic regression model were selected from the univariate analysis according to P-value. Variables were offered to the model to assess the association between these factors and metritis cure. Additionally, the univariate logistic regression variables were offered to a recursive feature elimination to find the optimal subset of features for a machine learning algorithms analysis. Cows without vulvovaginal laceration had 1.91 higher odds of curing of metritis than cows with vulvovaginal laceration. Cows that developed metritis at >7 DIM had 2.09 higher odds of being cured than cows that developed metritis at ≤7 DIM. For rectal temperature, each degree Celsius above 39.4°C led to lower odds to be cured than cows with rectal temperature ≤39.4°C. Furthermore, milk production slope and milk production difference from the day before to the metritis diagnosis were essential variables to predict metritis cure. Cows that had reduced milk production from the day before to the metritis diagnosis had lower odds to be cured than cows with moderate milk production increase. The results from the multivariable logistic regression and receiver operating characteristic analysis indicated that cows developing metritis at >7 DIM, with increase in milk production, and with a rectal temperature ≤39.40°C had increased likelihood of cure of metritis with an accuracy of 75%. The machine learning analysis showed that in addition to these variables, calving-related disorders, season, and month of metritis event were needed to predict whether the cow will cure or not from metritis with an accuracy ≥70% and F1 score (harmonic mean between precision and recall) ≥0.78. Although machine learning algorithms are acknowledged as powerful tools for predictive classification, the current study was unable to replicate its potential benefits. More research is needed to optimize predictive models of metritis cure.

Cow-level factors associated with subclinical hypocalcemia at calving in multiparous Jersey cows.

The objective of our study was to identify cow-level factors associated with subclinical hypocalcemia at calving (SCH) in multiparous Jersey cows. A total of 598 Jersey and 218 Jersey × Holstein crossbreed cows from 2 commercial dairy herds were enrolled in a retrospective cohort study. Blood samples to determine total Ca concentration were collected from the coccygeal vessels at 3 h 19 min (±2 h 33 min) after calving. We used 2 serum Ca concentration thresholds to define SCH: <2.00 mmol/L (SCH-2.00) and <2.12 mmol/L (SCH-2.12). We evaluated the association of cow-level factors with SCH with multivariable Poisson regression models. Variables evaluated for association with SCH were herd; parity (2, 3, and ≥4); breed; previous lactation length and 305-d mature-equivalent milk yield; previous lactation first test milk yield and last test somatic cell count; lengths of calving interval, gestation, dry, and close-up periods; body condition and locomotion scores at calving; calving ease; and calf sex for singletons. We categorized continuous variables into quartiles (≤25th percentile, interquartile range and ≥75th percentile). The prevalence of SCH among Jersey cows was 40 (SCH-2.00) and 64% (SCH-2.12). Jersey cows of higher parity had greater risk of SCH-2.00 and SCH-2.12. The risk of SCH-2.12 was higher after birthing male calves. We also found a tendency for previous lactation length and previous lactation 305-d mature-equivalent milk yield effect to affect risk of SCH-2.12. The risk of SCH-2.12 was lower for cows that had a previous lactation length shorter than the 25th percentile compared with cows that had a previous lactation length within the interquartile range. The risk of SCH-2.12 was higher for cows that had a previous lactation 305-d mature-equivalent milk yield below the 25th percentile compared with cows that had a previous lactation 305-d mature-equivalent milk yield above the 75th percentile. Also, Jersey × Holstein crossbreed was associated with increased risk of SCH-2.00. In the multivariable analysis, we observed no association between SCH and previous lactation first test milk yield; last test somatic cell count; lengths of calving interval, gestation, dry, and close-up periods; body condition and locomotion scores at calving; and calving ease. Our study identified parity, breed, calf sex, previous lactation length, and previous lactation 305-d mature-equivalent milk yield as cow-level factors associated with SCH in multiparous Jersey cows.

Technical note: Glucose concentration in dairy cows measured using 6 handheld meters designed for human use.

The objective was to evaluate the precision and accuracy of 6 handheld glucose meters, designed for human use [Accu-Chek Aviva Plus (AC), Roche Diabetes Care, Mannheim, Germany; Aga Matrix (AM), AgaMatrix Inc., Salem, NH; Contour Next (CT), Bayer HealthCare LLC, Leverkusen, Germany; FreeStyle Precision Neo (FS), Abbott Diabetes Care Ltd., Alameda, CA; Nova Max Plus (NM), Nova Biomedical Corporation, Waltham, MA; and Precision Xtra (PX), Abbott Diabetes Care Ltd., Witney, UK] to measure blood glucose concentration in dairy cows. Blood samples from Jersey and Jersey × Holstein crossbreed cows (n = 97 for all; except CT, n = 71) were collected and analyzed in triplicate using the 6 handheld glucose meters evaluated. Plasma glucose was also measured with the laboratory reference method (hexokinase glucose-6-phosphate dehydrogenase). Based on the intra-assay coefficient of variation (CV), precision varied across handheld glucose meters: AC (2.2%), CT (4.0%), PX (4.7%), FS (5.6%), AM (6.2%), and NM (6.7%). Lin's concordance correlation coefficients between handheld glucose meters and the reference method were 0.75 for FS, 0.74 for PX, 0.62 for AC, 0.55 for CT, 0.53 for NM, and 0.48 for AM. Based on Passing-Bablok regression, the AM and PX meters showed bias in the measurements of blood glucose. Bland-Altman plots indicated a negative bias (FS = -0.25 mmol/L; CT = -0.60 mmol/L) or a positive bias (AM = 0.29 mmol/L; PX = 0.33 mmol/L; NM = 0.52 mmol/L; AC = 0.65 mmol/L) between handheld glucose meters and the reference method. All handheld glucose meters evaluated had wide limits of agreement (LoA) ranging from -0.18 to 1.47 mmol/L (AC, narrowest LoA) to -1.25 to 1.82 mmol/L (AM, widest LoA). Bias was the major contributor to the total observed error (TEobs), accounting for 81.5% of the TEobs in AC, 72.0% in CT, 64.9% in AM, 61.1% in NM, 57.8% in PX, and 56.2% in FS. Overall, although some handheld meters (AC, CT, and PX) showed satisfactory precision, none were accurate measuring glucose. Future studies should evaluate whether incorporating algorithms designed for cattle can improve accuracy and precision of handheld glucose meters.

Effect of prophylactic oral calcium supplementation on postpartum mineral status and markers of energy balance of multiparous Jersey cows.

The effects of prophylactic oral Ca supplementation on blood mineral status and markers of energy balance were evaluated on 205 multiparous Jersey cows at a commercial dairy. Postpartum, cows were systematically assigned to control (n = 105) or oral Ca supplementation (CaOS; 50 to 60 g of Ca as boluses; n = 100) at 0 and 1 d in milk (DIM). Blood samples for analysis of serum minerals (Ca, P, Mg, K, Na, Fe, Zn, and Cu) were collected before and 1 h after treatment at 0 and 1 DIM, and at 2 DIM. Urine pH was measured immediately before and 1 h after treatment administration (n = 96). A subset of 74 cows was evaluated for plasma glucose and fatty acid concentrations at 0, 1, and 2 DIM. Cows were classified according to their initial calcemic status (Ca status) as normocalcemic (NC; serum Ca >2.12 mmol/L) or subclinically hypocalcemic (SCH; serum Ca ≤2.12 mmol/L). Average serum Ca concentration was higher in CaOS than control cows (2.12 vs. 2.06 mmol/L); this treatment effect was higher for SCH [CaOS (2.03 mmol/L); control (1.89 mmol/L)] than NC cows [CaOS (2.22 mmol/L); control (2.22 mmol/L)]. The incidence of subclinical hypocalcemia was lower for CaOS than control cows (53 vs. 65%); however, at 2 DIM the prevalence of subclinical hypocalcemia tended to be higher for CaOS cows, mostly because it was higher for CaOS-NC than control-NC cows (70 vs. 25%). Urine pH was lower for CaOS than control cows (6.10 vs. 7.04). Lower serum Mg concentration was detected for CaOS-SCH (1.06 mmol/L) than for control-SCH (1.10 mmol/L) cows. Cows in the CaOS group had higher serum K (4.68 vs. 4.53 mmol/L), lower plasma glucose (2.97 vs. 3.10 mmol/L), and at 2 DIM higher plasma fatty acid concentrations (0.43 vs. 0.35 mmol/L) than control cows. Our results showed that postpartum serum Ca concentration increases with oral Ca supplementation, but calcemic status influenced treatment response. Future studies should evaluate the long-term implications on production and reproduction of oral Ca supplementation in Jersey cows.

Metritis diagnosis and treatment practices in 45 dairy farms in California.

Minimizing the risk of antimicrobial-resistant organisms and antimicrobial residues in dairy and dairy beef products is a topic of nationwide interest. To design an effective outreach program on judicious use of antimicrobials, it is imperative to describe actual practices on dairies. Thus, our objective was to report current practices for metritis treatment in 45 dairies in California. Data were collected using a survey tool that included questions on systemic antimicrobial treatments, intrauterine treatments, supportive treatments, and treatment records. Researchers collected information based on cow-side observations and responses from fresh cow evaluators. Most dairies (n = 33; 70%) performed rectal exams for vaginal discharge (VD) evaluation and based systemic antimicrobial administration on the presence of (a) abnormal VD (fetid and nonfetid), regardless of fever (n = 11; 25%); (b) fever regardless of the odor of abnormal VD (n = 11; 25%); (c) fetid VD and fever (n = 1; 2%); (d) fetid VD (n = 3; 9%); or (e) fetid VD or fever (n = 3; 9%). Some dairies (n = 11; 24%) only detected abnormal VD if visible on tail, vulva, or floor; treatment decisions were based on the presence of abnormal VD (n = 9; 20%) or abnormal VD and fever (n = 2; 4%). On 3 (6%) dairies, VD characteristics were evaluated after rectal palpation, but no systemic treatments were administered. Cows exhibiting 1 nonspecific sign of health disorder (depressed general appearance, lack of appetite, or drop in milk yield) plus fever (n = 13; 29%), or even regardless of fever (n = 6; 13%), were treated with systemic antimicrobials. Overall, 8 (18%) dairies justified systemic antimicrobial treatment based on fever alone. Systemic antimicrobials used were ceftiofur products [ceftiofur hydrochloride (n = 26; 55%), ceftiofur sodium (n = 3; 7%), and ceftiofur crystalline-free acid (n = 8; 18%)], penicillin procaine (n = 8; 18%), and ampicillin (n = 3; 7%). Intrauterine infusions were done with penicillin procaine (n = 1; 2%) or oxytetracycline (n = 12; 27%). The dose and treatment length varied across dairies for i.m. ceftiofur hydrochloride (15 to 45 mL/d for 3 to 5 d), s.c. ceftiofur crystalline-free acid (20 to 25 mL once or twice), i.m. ceftiofur sodium (15 to 30 mL/d for 3 to 5 d), i.m. penicillin procaine (20 to 60 mL/d for 3 to 6 d), and i.m. ampicillin (25 to 35 mL/d for 3 to 6 d). The antimicrobial drug of choice, the dose, and the treatment length for metritis varied across the study dairies. Based on accepted industry best-management practices for metritis, a need exists to educate fresh cow evaluators on signs of health disorder indicative of metritis and on appropriate antimicrobial treatment regimens.

Efficacy of colostrum replacer versus maternal colostrum on immunological status, health, and growth of preweaned dairy calves.

Commercially available colostrum replacers (CR) are commonly used when maternal colostrum (MC) is unavailable, for managerial convenience, to ensure quality consistency at first feeding, or in disease control and eradication programs. The objective of this study was to determine the efficacy of feeding First Day Formula (Accelerated Genetics, Baraboo, WI) CR versus pooled MC on immunological status, growth, and health of preweaned dairy calves. A total of 1,220 Jersey and Jersey × Holstein calves born on a California Central Valley dairy farm were assigned after birth to receive either CR or MC following a systematic allocation procedure. Calves assigned to MC were tube fed 2.8 L of MC, and calves assigned to CR were tube fed a total of 500 g of CR (150 g of immunoglobulin G; IgG) mixed into 1.9 L of water at 1 h ± 5 min after the calf was born. A subset of calves was selected for passive transfer (n = 592) and growth (n = 268) analyses. Although both coliform count and total bacteria count were low for MC and CR fed to calves during the study, the predicted probability of calves receiving contaminated liquid feed (coliform count >10,000 cfu/mL) at first feeding was reduced for calves fed CR (1.5%) compared with calves fed MC (6.1%). The mean blood concentration of IgG was lower for calves fed CR than for calves fed MC (19.6 vs. 23.4 mg/mL). However, the apparent efficiency of absorption of IgG did not differ between treatments (34.4 and 35.9% for CR and MC, respectively). Total proteins were lower in calves fed CR compared with MC at 24 h (5.16 vs. 5.84 g/dL, respectively). Calves fed CR were 1.5 kg lighter at weaning and gained 0.03 kg less per day (0.30 vs. 0.33 kg/d, respectively) than calves fed MC before weaning. Height at weaning did not differ between the 2 treatment groups. Calves fed CR tended to have a higher predicted probability of not being treated for diarrhea than calves fed MC (0.142 vs. 0.110, respectively). However, when the disease was present, CR had a higher number of treatment days compared with MC (11.6 vs. 10.8 d, respectively). The hazard ratio of dying did not differ between MC and CR; however, CR calves had a numerically higher risk (hazard ratio = 1.347) of dying compared with calves that received MC. In conclusion, IgG absorption and serum concentration of calves were adequate when calves were fed either CR or MC. The CR-fed calves had a lower probability of receiving contaminated liquid feed and performed similar in terms of health compared with calves receiving high-quality MC, although they were slightly lighter at weaning. Therefore, the CR evaluated in this study is a valid alternative to high-quality (>50 mg of IgG/mL) MC.

Effect of hoof trimmer intervention in moderately lame cows on lameness progression and milk yield.

The objective of this study was to evaluate the effect of hoof trimmer intervention (HTI) in moderately lame cows on lameness progression and milk yield. Two freestall Holstein herds were enrolled. Cows were milked 2 (herd A: 2,374 cows) or 3 (herd B: 2,800 cows) times a day. Within each dairy, moderately lame cows [locomotion score (LS) = 3 on a 5-point scale] were randomly assigned to control group (CON; herd A = 66, herd B = 84) or treatment group (HTI; evaluated and treated by the hoof trimmer under researchers' supervision; herd A = 73; herd B = 75). Enrollment criteria were <350 d in milk, <180 d pregnant, >10 kg/d of milk yield, not selected for therapeutic trimming 2 mo before enrollment, and >14 observations of daily milk yield during the study period. Biweekly lameness scoring (LS ≤2, LS = 3, LS ≥4) was conducted up to 6 wk post-intervention. Lesion type and severity records were collected at intervention from HTI cows and up to 6 wk post-intervention from all enrolled cows identified as lame by farm employees. Daily milk yield data were collected from -1 to 6 wk relative to intervention using Afifarm (Afimilk Ltd., Kibbutz Afikim, Israel) records. No treatment effect was detected on the predicted probability of locomotion score, but the predicted probability of LS ≥3 decreased over time in herd B, whereas in herd A, it initially decreased but later increased. A tendency for a treatment by time interaction was observed in herd A; at 2 wk post-intervention, the predicted probability for LS ≥3 was higher for HTI (0.69) than for CON (0.43), but similar at 4 wk (0.41 HTI, 0.49 CON) and 6 wk (0.77 HTI, 0.73 CON). At intervention, most study cows had no lesions (41.2%), sole hemorrhages (28.4%), thin soles (8.8%), or vertical fissure (6.8%). During the 6 wk following intervention, a similar proportion of cows were identified as lame in CON (8.7%) and HTI (6.7%) groups. In herd A, milk yield (least squares means ± standard error) was similar for CON (42.0 ± 0.77 kg/d) and HTI (42.3 ± 0.75 kg/d) cows, whereas in herd B, it tended to be lower for HTI (43.7 ± 0.61 kg/d) than for CON (45.2 ± 0.59 kg/d) cows. A significant effect of time was detected on both dairies, with milk yield decreasing over the study period. In our study, implementing HTI on moderately lame cows resulted in no improvement in gait or milk yield. The low presence of severe lesions amenable to therapy may partially explain our findings.

Colostrum immunoglobulin G concentration of multiparous Jersey cows at first and second milking is associated with parity, colostrum yield, and time of first milking, and can be estimated with Brix refractometry.

The objective of this study was to evaluate colostrum IgG concentration harvested at first and second milking from multiparous Jersey cows, the dam's lactation number, colostrum yield, and time of first milking. In addition, we validated the use of a Brix refractometer to estimate IgG concentration in colostrum from multiparous Jersey cows using radial immunodiffusion as the reference method. Colostrum samples and total weight of colostrum harvested at first (n = 134) and second (n = 68) milking were collected from 134 multiparous Jersey cows housed in a California herd. Fresh colostrum samples were analyzed for IgG concentration with Brix refractometry and frozen samples by radial immunodiffusion. A total of 90.4 and 42.7% of the samples from first and second milking met industry standards of quality for IgG concentration (>50 g/L). Second and third lactation cows had similar colostrum IgG concentration but lower than cows on their fourth and greater lactation. At second milking, 56.4% of cows on their fourth or greater lactation had colostrum IgG concentrations >50 g/L. When colostrum yield increased from low (<3 kg), medium (3 to 6 kg), to high (>6 kg), IgG concentration decreased. Higher IgG concentration was observed on colostrum harvested at <6 h (short) versus 6 to 11 h (medium) after calving. However, IgG concentration in colostrum harvested after 11 h (long) was similar to that harvested at short and medium time. Readings of %Brix were highly correlated with IgG at first (r = 0.81) and second (r = 0.77) milking. The best Brix threshold to identify colostrum from first milking with >50 IgG g/L was 20.9% based on logit equations with Youden's index criterion and 18.0% based on accuracy criterion. For colostrum harvested at second milking, similar Brix thresholds were obtained, 19.2 and 19.0%, regardless of whether Youden's index or accuracy was used as the selection criterion. Our results indicate that the dam's lactation number, colostrum yield, and time of first milking relative to calving are associated with IgG concentration in colostrum from multiparous Jersey cows. Second milking colostrum from mature Jersey cows should be evaluated to extend colostrum supply on dairies especially during times of shortage. Readings of %Brix can be used to rapidly estimate IgG concentration in Jersey colostrum harvested at first and second milking.

A survey of silage management practices on California dairies.

The aim of the present study was to gather baseline information on corn silage-management practices to develop an outreach curriculum for dairy producers and growers. In spring 2013, dairy producers in the San Joaquin Valley (California) were surveyed on their silage-management practices. Response rate was 14.5% (n=160) and herd size averaged 1,512 milking cows. Harvest date was set solely by the dairy producer (53.4%) or with the assistance of the crop manager, custom chopper, or nutritionist (23.3%). On some dairies (23.3%), the dairy producer delegated the harvest date decision. Most dairies (75.0%) estimated crop dry matter before harvest, and the preferred method was milk line evaluation. Dairy producers were mostly unfamiliar with harvest rate but the number [1 (35.9%), 2 (50.3%), or 3 to 5 (13.8%)] and size [6-row (17.7%), 8-row (67.3%), or 10-row (15.0%)] of choppers working simultaneously was reported. Most dairies used a single packing tractor (68.8%) and weighed every load of fresh chopped corn delivered to the silage pit (62%). During harvest, dry matter (66.9%), particle length (80.4%), and kernel processing (92.5%) were monitored. Most dairies completed filling their largest silage structure in less than 3 d (48.5%) or in 4 to 7 d (30.9%). Silage covering was completed no later than 7 2h after structure completion in all dairies, and was often completed within 24 h (68.8%). Packed forage was covered as filled in 19.6% of dairies. Temporary covers were used on some dairies (51.0%), with filling durations of 1 to 60 d. When temporary covers were not used, structures were filled in no more than 15 d. After structure closure, silage feedout started in 1 to 3 wk (44.4%), 4 to 5 wk (31.4%), or 8 or more wk (24.2%). Future considerations included increasing the silage storage area (55.9%), increasing the number of packing tractors (37.0%), planting brown mid-rib varieties (34.4%), buying a defacer to remove silage (33.1%), and creating drive-over piles (32.6%). Survey results will serve to develop and disseminate targeted information on silage management practices at harvest, packing, covering, and feedout on California's San Joaquin Valley dairies.

Deviation from the formulated target weight of ingredients loaded into high milk yield cow recipes on California dairies.

Nutrient composition of the feed and formulated ration often differ depending on uncertainties in DM content and nutrient composition of ingredients, as well as from feeder errors during loading. The objective of this study was to describe the deviation from target weight for the high-producing cow ration (HCR) and premix (HCP) on 26 California dairies ranging in size from 1,100 to 6,900 cows. Records from a consecutive 12-mo period were extracted from FeedWatch 7 (Valley Agricultural Software Inc., Tulare, CA), a feeding management software. Variables extracted and studied were date, recipe type, recipe number, ingredient, loading sequence, target weight, weight, and tolerance level (TL, deviation allowed per ingredient during loading). Based on the distribution of the deviation from target weight for the 8 most common ingredients, loading accuracy (quartile 1; small: |<10| kg; medium |10| to |20| kg; large |>20| kg), loading precision (interquartile range=quartile 3 to 1; small: <20kg; medium: 20 to 40kg; large >40kg), and extreme observations (quartile 3; small: |<25| kg; medium: |25| to |40| kg; large: |>40| kg) were described. Descriptive statistics were conducted with SAS 9.4 (SAS Institute Inc., Cary, NC). The median TL assigned to ingredients across dairies ranged from 0 to 90kg. At the ingredient level, the TL allowed a deviation from the median ingredient target weight of 0 to 2 (53.9%), >2 to 5 (25.5%), >5 to 10 (11.6%), or >10% (8.9%). A total of 2.5% of the loads did not reach the target weight set by the TL, ranging from 0.1 to 21.1% loads across dairies. Ingredient deviation from the formulated target weight across dairies was below target 49.1% of the time [<-10 (2.5%), -10 to <-5 (4.8%), -5 to <-2 (8.9%), -2 to <0% (32.8%)] or at or above target 50.9% of the time [0 (3.9%), >0 to 2 (36.7%), >2 to 5 (8.9%), >5 to 10 (1.2%), >10% (0.2%)]. Five dairies loaded ingredients with adequate accuracy (small to medium, quartile 1) and adequate precision (small to medium, interquartile range), but accuracy and precision were very poor on 3 dairies (large, quartile 1 and interquartile range). Rolled corn and almond hulls were loaded with adequate precision (small to medium, interquartile range) on a minimum of 64% of the dairies and adequate accuracy (small, quartile 1) on at least 68% of the dairies. In contrast, alfalfa hay, corn silage, and canola were loaded with poor precision (large, interquartile range) on a minimum of 60% of the dairies. There was a large variation within and across dairies on the deviation from target weight. Readjusting the TL settings might reduce the deviation from target weight. On 5 dairies, feeders were able to load ingredients with minimal deviation from target weight, setting achievable goals for the industry. Based on loading errors, opportunities exist to improve feeder performance on California dairies.

Fresh-cow handling practices and methods for identification of health disorders on 45 dairy farms in California.

The aim of the present study was to describe fresh-cow handling practices and techniques used during fresh cow evaluations to identify postpartum health disorders on 45 dairy farms in California ranging from 450 to 9,500 cows. Fresh cow practices were surveyed regarding (a) grouping and housing, (b) scheduling and work organization, (c) screening for health disorders, and (d) physical examination methods. Information was collected based on cow-side observations and responses from fresh cow evaluators. Cows were housed in the fresh cow pen for 3 to 14 (20%), 15 to 30 (49%), or >31 (31%) d in milk. Fresh cow evaluations were performed daily (78%), 6 times a week (11%), 2 to 5 times a week (9%), or were not routinely performed (2%). There was significant correlation between the duration of fresh cow evaluations and the number of cows housed in the fresh pen. Across all farms, the duration of evaluations ranged from 5 to 240 min, with an average of 16 s spent per cow. During fresh cow checks, evaluators always looked for abnormal vaginal discharge, retained fetal membranes, and down cows. Dairies evaluated appetite based on rumen fill (11%), reduction of feed in the feed bunk (20%), rumination sensors (2%), or a combination of these (29%). Milk yield was evaluated based on udder fill at fresh cow checks (40%), milk flow during milking (11%), milk yield records collected by milk meters (2%), or a combination of udder fill and milk meters (5%). Depressed attitude was evaluated on 64% of the dairies. Health-monitoring exams for early detection of metritis were implemented on 42% of the dairies based on rectal examination (13%), rectal temperature (22%), or both (7%). Dairies implementing health-monitoring exams took longer to perform fresh cow evaluations. Physical examination methods such as rectal examination, auscultation, rectal temperature evaluation, and cow-side ketosis tests were used on 76, 67, 38, and 9% of dairies, respectively. Across dairies, we found large variation in signs of health disorders screened and how those signs were evaluated. Fresh cows were primarily evaluated based on nonspecific and subjective observations during screening. Future research efforts should focus on developing and validating scoring systems to more objectively identify health disorders in postpartum cows.

Effects of subcutaneous calcium administration at calving on mineral status, health, and production of Holstein cows.

The objective of this study was to determine effects of subcutaneous (s.c.) infusions of Ca at calving day on serum concentrations of Ca, P, Mg, ß-hydroxybutyrate (BHB), glucose, body condition score (BCS), milk yield, and health in fresh cows receiving a dietary cation-anion difference diet during the dry period. Three hundred seventy-five fresh Holstein cows were blocked based on parity (143 cows in first parity, 108 cows in second parity, and 124 cows in third or greater parity) and randomly assigned to 1 of 4 experimental treatments immediately after calving. Treatments were control group without infusion (control; n=190); 1 s.c. infusion of 250mL of 40% Ca borogluconate (1SC250; n=72) at calving; 1 s.c. infusion of 500mL of 40% Ca borogluconate (1SC500; n=63) at calving; 2 s.c. infusions of 250mL of 40% Ca borogluconate, one immediately after calving and the second 12 to 18h after first infusion (2SC250; n=50). Blood samples were collected immediately after parturition and at 1, 2, 4, and 7d in milk (DIM) for Ca, P, and Mg determination. Milk production, milk composition, and somatic cell count were recorded monthly up to 90 DIM. The evaluation of BCS was performed at calving and at 38 DIM. A subset of 9 cows per treatment group was randomly chosen to measure serum concentration of glucose and BHB at 2, 4, and 7 DIM. Total serum Ca in 1SC250 (8.95mg/dL), 1SC500 (9.27mg/dL), and 2SC250 (9.07mg/dL) was greater during the first week postpartum compared with control (8.45mg/dL). Serum concentrations of P, Mg, BHB, glucose, and milk yield were not affected by treatments. The dry matter intake during the first 24h after calving was higher for treatments 1SC250 (13.5kg), 1SC500 (15.0kg), and 2SC250 (15.6kg) relative to control (12.5kg). Milk somatic cell counts were lower for 1SC500 (90.5 cells/mL) and 2SC250 (82.2 cells/mL) than control (132.8 cells/mL). Risk ratio was >1 for development of metritis, and clinical and subclinical endometritis in control cows relative to 2SC250 cows, which indicates a higher risk of developing disease for control cows (2.03, 1.7, and 1.8 times, respectively). These results suggest that prophylactic s.c. infusions of Ca at calving can improve postpartum Ca status in Holstein cows and intake at 1 DIM. Given the reduction of metritis, clinical and subclinical endometritis, and subclinical hypocalcemia with treatment, the effect of s.c. Ca supplementation on immune status warrants further investigation.

Blood calcium dynamics after prophylactic treatment of subclinical hypocalcemia with oral or intravenous calcium.

Total serum Ca dynamics and urine pH levels were evaluated after prophylactic treatment of subclinical hypocalcemia after parturition in 33 multiparous Jersey × Holstein crossbreed cows. Cows were blocked according to their calcemic status at the time of treatment [normocalcemic (8.0-9.9 mg/dL; n = 15) or hypocalcemic (5.0-7.9 mg/dL; n = 18)] and randomly assigned to 1 of 3 treatments: control [no Ca supplementation (n = 11)]; intravenous Ca [Ca-IV (n = 11), 500 mL of 23% calcium gluconate (10.7 g of Ca and 17.5 g of boric acid as a solubilizing agent; Durvet, Blue Springs, MO)]; or oral Ca [Ca-Oral (n = 11), 1 oral bolus (Bovikalc bolus, Boehringer Ingelheim, St. Joseph, MO) containing CaCl2 and CaSO4 (43 g of Ca) 2 times 12h apart]. Total serum Ca levels were evaluated at 0, 1, 2, 4, 8, 12, 16, 20, 24, 36, and 48 h, and urine pH was evaluated at 0, 1, 12, 24, 36, and 4 8h after treatment initiation. Total serum Ca levels were higher for Ca-IV than for control and Ca-Oral cows at 1, 2, and 4h after treatment initiation, but lower than Ca-Oral cows at 20, 24, and 36 h and lower than control cows at 36 and 48 h. At 1h after treatment initiation, when serum Ca levels for Ca-IV cows peaked (11.4 mg/dL), a greater proportion of Ca-IV (n = 8) cows had total serum Ca levels >10mg/dL than control (n = 0) and Ca-Oral (n = 1) cows. At 24h after treatment initiation, when Ca-IV cows reached the total serum Ca nadir (6.4 mg/dL), a greater proportion of Ca-IV (n = 10) cows had serum Ca levels <8 mg/dL than control (n = 5) and Ca-Oral (n = 2) cows. Treatment, time, and treatment × time interaction were significant for urine pH. Mean urine pH was lower for Ca-Oral cows (6.69) than for control (7.52) and Ca-IV (7.19) cows. Urine pH levels at 1h after treatment were lower for Ca-IV cows compared with both control and Ca-Oral cows, a finding likely associated with the iatrogenic administration of boric acid added as a solubilizing agent of the intravenous Ca solution used. At 12, 24, and 36 h, urine pH levels were lower for Ca-Oral cows compared with both control and Ca-IV cows. This was expected because the oral Ca supplementation used (Bovikalc) is designed as an acidifying agent. Wide fluctuations in blood Ca were observed after prophylactic intravenous Ca supplementation. The implications for milk production and animal health, if any, of these transient changes in total serum Ca have yet to be evaluated.

Mineral concentrations in diets, water, and milk and their value in estimating on-farm excretion of manure minerals in lactating dairy cows.

Thirty-nine commercial dairies in Merced County, California were enrolled in the present study to (1) compare lactating cow mineral intakes (via drinking water and total mixed ration) to the National Research Council (NRC) requirements, (2) evaluate the association between dietary concentrations of minerals with and without drinking water and adjusted for mineral concentrations in milk, and (3) compare 4 different methods to estimate excretion of minerals using either assays or estimations of milk mineral outputs and total daily mineral intake per cow with or without minerals coming from drinking water. Dairies were selected to represent a range of herd milk yields and a range of water mineral contents. Samples of total mixed ration, drinking water, and bulk tank milk were taken on 2 different days, 3 to 7d apart in each farm. Across-farm medians and percentile distributions were used to analyze results. The herd median milk yield interquartile ranged (10th to 90th percentile) from less than 25 to more than 39 kg/d and the concentration of total solids in water interquartile ranged from less than 200 to more than 1,490 mg/L. Including drinking water minerals in the diets increased dietary concentrations by <4% for all minerals except for Na and Cl, which increased by 9.3 and 6.5%, respectively. Concentrations of P and K in milk were essentially the same as the NRC value to estimate lactation requirements. However, NRC milk values of Ca, Cl, and Zn were 10 to 20% greater than dairy farm values; and Na, Cu, Fe, and Mn were no less than 36% below NRC values. Estimated excretion of minerals via manure varied substantially across farms. Farms in the 10th percentile did have 2 to 3 times less estimated mineral excretions than those in the 90th percentile (depending on the mineral). Although including water minerals increased excretion of most minerals, the actual median effect of Ca, Mg, S, Cu, Fe, and Mn was less than 5%, and about 8% for Na and Cl. Replacing assayed concentrations of minerals in milk with NRC constants resulted in reduced estimated excretion of Ca, Na, Cu, Fe, and Zn, but median differences were <5% except for Na which was 7.5%. Results indicate that not including mineral intake via drinking water and not using assayed concentrations of milk minerals lead to errors in estimation manure excretion of minerals (e.g., Ca, Na, Cl, and S).