Effect of a 2-step probiotic program on digestive health and performance of Holstein heifer calves.

Managing the composition of the bacterial communities in the digestive tract with the use of probiotics that enhance protective microflora could result in positive effects on health and performance of calves. The objective of this study was to evaluate a 2-step probiotic program (added to colostrum and milk) on the digestive health and growth of preweaning Holstein heifers. A randomized clinical trial was conducted from July to October 2020 in a calf rearing facility in Colorado. Calves were housed in pairs sharing the same treatment in 2 polyethylene hutches within a common area of 4.50 m2. A total of 232 calves were enrolled at birth and randomly allocated into 2 treatment groups [control (CTR) = 116; treatment (PB) = 116] and followed until weaning (64 ± 3 d). Treatment consisted of 2 formulations of a multistrain bacterial-based probiotic added in colostrum (PBF1) and milk (PBF2). Treatment calves received 2 g of PBF1 added to each colostrum feeding, and 1 g of PBF2 added to the milk at the morning feeding 3 times per week up to weaning. Calf weight was collected at birth, at 30 d of age, and at weaning. Serum total protein was determined at age 3 ± 1 d and a health assessment was completed 3 times per week. Statistical analyses were performed using SAS, with calf considered the experimental unit clustered by housing pair. Cox proportional hazard analysis and time to event analysis were used to compare time to the first diarrhea event and time to recovery between treatment groups. The total number of diarrhea events and culling were assessed by Poisson regression and logistic regression analysis, respectively. Linear regression was performed to evaluate differences in average daily gain by treatment group. Overall, the mean (± standard error) temperature humidity index (THI) was 75 (± 0.44) units during the study period, which resulted in continuous exposure to heat stress in the day hours. No difference between treatment groups was observed in serum total protein. The overall incidence of diarrhea was 96.6% (CTR = 99%, PB = 95%); no differences were determined in the hazard of a first diarrhea episode or in the median time to the first diarrhea event (11 d in both groups). Similarly, no differences were found in the likelihood of recovery or in the median time to recovery from diarrhea (7 d in both groups). Likewise, treatment group was not associated with the number of diarrhea events, mean (± standard error, g/d) average daily gain from birth to weaning [CTR = 562.5 (13.9); PB = 570.8 (13.5)], or with the odds of culling. The most prevalent pathogen isolated from feces was Clostridium, which tended to be more frequent in CTR calves than PB calves. In conclusion, the probiotic program did not affect the incidence of enteric disease or the growth of preweaning heifer calves.

Incidence and risk factors for reproductive disorders in organic certified dairies.

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

Effect of aluminized reflective hutch covers on calf health and performance.

The effect of polyethylene hutches wrapped in aluminized reflective covers (ARC) on health and performance of pre-weaned Holstein heifers during summer was evaluated. Ambient and hutch temperature and temperature-humidity index (THI) were also assessed. The study was conducted from June to October 2016 where temperature, humidity, and THI ranged from -1.3 to 38.4°C, 9.8 to 99.7%, and 33.6 to 81.1 units, respectively. Heifers enrolled at 1 d of life and housed in individual polyethylene hutches with (covered) or without (control) ARC were monitored until 60 d of life in 2 study groups (SG1, n = 94, monitored from June to September; and SG2, n = 101, monitored from August to October 2016). Calves were assessed twice per week for health status, behavior, rectal temperature, and respiratory rate. Similarly, hutch inner wall and sand bedding temperatures were determined for comparison between covered and control hutches housing calves. Four empty hutches per treatment group were continuously monitored for temperature and THI. The odds (95% confidence interval) of presenting diarrhea were 1.30 (1.01-1.60) times greater for calves housed in covered hutches than for those in the control group. Similarly, the odds of an abnormal ear score were 1.40 (1.03-2.00) times greater for calves in covered hutches compared with calves in control hutches. The odds of nasal discharge, eye discharge, and clinical dehydration did not differ between treatment groups. Rectal temperatures and respiratory rates were also similar in both groups. No differences were found in average daily gain between calves housed in covered and control hutches. Calf location determined at a fixed time during the day (starting at 1200 h) was associated with the use of ARC. The odds of remaining inside the hutch were 1.33 (1.03-1.70) times greater for calves housed in control compared with covered hutches. Overall, the average of hutch interior temperature was higher in covered compared with control hutches in both studies (SG1, 23.2 ± 0.06 vs. 22.8 ± 0.06°C; SG2, 17.1 ± 0.07 vs. 16.9 ± 0.07°C). Hutch THI was higher in covered empty hutches compared with control hutches in both study groups (SG1: 68.6 ± 0.06 vs. 67.6 ± 0.06°C; SG2: 60.2 ± 0.08 vs. 59.6 ± 0.08°C). Average temperature (measured at 1200 h) of the inner surface of the hutch wall was lower in covered compared with control hutches by 1°C (24.4 ± 0.13 vs. 25.4 ± 0.13°C), whereas the temperature of the sand bedding did not differ between groups. Our results suggest that the use of ARC did not generate a hutch microclimate that resulted in significant improvements on health and performance of pre-weaned dairy calves under these specific study settings.

Season of conception is associated with future survival, fertility, and milk yield of Holstein cows.

Environmental influences during different stages of pregnancy can induce lifelong changes in the structure, physiology, and metabolism of the offspring. Our hypothesis was that season of conception (when the offspring was conceived), associated with heat stress conditions at conception and during the initial stages of embryonic development, affects the lifetime performance and survival of the female offspring after birth. The objective was to analyze the association between month of conception and subsequent survival, fertility, and milk yield in cows maintained on dairy farms in Florida, where the climate during the summer is hot and humid but winters are mild. Initial data consisted of 667,104 Dairy Herd Improvement lactation records from cows calving between 2000 and 2012 in 152 herds. Dates of conception were estimated as birth date minus 280 d. The magnitude of heat stress in each herd was quantified by comparing milk yield during summer and winter. Wood's lactation curves were fitted to adjust milk yields for effects of days in milk, and residuals were obtained for each calendar month. A sine function was fitted on the 12 residuals per farm. The difference between the highest and lowest points on the sine function was termed the seasonality index, a measure of the direct effect of heat stress on milk production. Herds were categorized in 3 levels of seasonality [low (seasonality index values less than the 25th percentile value; <2.84), medium (values within the interquartile range), and high (values greater than the 75th percentile value; >5.22)]. Cows were grouped by their month of conception: summer (July-September) and winter (December-February), and comparisons were performed by parity using logistic regression, ANOVA, and survival analysis. Two models were developed. Model A included the complete population of cows (n = 337,529 lactation records) conceived in winter or summer. Model B included cows (n = 228,257 lactation records) that had parent-average genetic information available to be able to correct for farmer's use of lower genetic merit of sires in summer. Other variables included in the models were month and year of calving, age at first calving, and herd. Models were run per parity group (1, 2, and ≥3). In both models, age at first calving was lower for cows conceived during winter versus summer. The odds (95% confidence interval) of survival to a second calving for cows conceived in winter were 1.21 and 1.15 times the odds of survival for cows conceived in summer for models A and B, respectively. Numbers of days from calving to first breeding and from calving to conception were consistently smaller for winter versus summer months of conception across all parity categories. Milk yields (305 d and by 70 d in milk) were greater for cows conceived in winter versus summer. In conclusion, cows that were conceived in the winter had better subsequent survival and performance than cows that were conceived in the summer. There is evidence that season of conception may have lifelong consequences for the offspring.

Effect of housing type on health and performance of preweaned dairy calves during summer in Florida.

The objective was to evaluate the effect of housing type on health and performance of preweaned dairy calves. One hundred calves, Holsteins (HO) or Holstein-Jersey crosses (HJ), were randomly assigned to a Calf-Tel (L. T. Hampel Corp., Germantown, WI) polyethylene hutch exposed to direct sun light (n=25 for both HO and HJ) or a wire hutch with a plywood shade located under trees (n=24 and 26 for HO and HJ, respectively). Calf rectal temperature, respiratory rate, health scores, and weaning weight were compared by housing type. Rectal temperatures were higher in calves in Calf-Tel hutches compared with calves in wire hutches at 1500 h, at 40.1±0.28 and 39.1±0.22°C, respectively. Similarly, respiratory rates were higher in calves in Calf-Tel hutches compared with calves in wire hutches at 1500 h, at 90±15 and 65±10 breaths per minute, respectively. Frequencies of calves presenting abnormal ear scores did not differ between calves in Calf-Tel or wire hutches. Abnormal eye scores were less likely to occur for calves in the wire hutches. Frequencies of calves with signs of respiratory disease, such as nasal discharge and coughing, were higher in the wire hutches compared with the Calf-Tel hutches. No differences were noted in the incidence and time of first diarrhea event in calves between hutch types. Calves in wire hutches had 5.47 greater odds of receiving veterinary treatment compared with calves in the Calf-Tel hutches. Weaning weights were not different for calves in Calf-Tel or in wire hutches. The lower frequency of calves with abnormal health scores and receiving veterinary treatment in Calf-Tel hutches and the lack of difference in weight gain suggests that this housing system adapted well to the specific environmental conditions of this study.

Effect of intrauterine infusion of an organic-certified product on uterine health, survival, and fertility of dairy cows with toxic puerperal metritis.

The objective was to evaluate the effect of intrauterine infusion of an organic certified product (Optimum UterFlush, Van Beek Natural Science, Orange City, IA) on uterine health, survival, and fertility of cows affected with toxic puerperal metritis (TPM) in an organic dairy farm. Cows with TPM were defined as having an abnormally enlarged uterus and a fetid watery red-brown vaginal discharge, associated with systemic illness and fever (rectal temperature ≥39.5°C), within 12 d postpartum. Cows diagnosed with TPM (n=220; study d 0) were blocked by parity (1 and ≥2) and randomly assigned into 1 of 2 intrauterine treatments applied every other day for a total of 3 applications: (1) control (CON)=200mL of povidone iodine diluted in 2L of distilled water (n=113); (2) Optimum UterFlush (UF)=3.75mL diluted in 117mL of distilled water (n=107). All enrolled cows received hypertonic saline solution (500mL 7.2% i.v.), dextrose (500mL 50% i.v.), and oral aspirin (5 boluses/d). Outcome variables for treatment efficacy included fever and presence of fetid vaginal discharge at study d 6 and 14, survival at study d 6 and 14 and at 30 and 100 DIM, and reproductive performance. Control variables were parity, BCS at enrollment, calving season, and milk yield. Occurrence of fever at d 6 and 14 was not different between the 2 treatment groups. Presence of fetid vaginal discharge at d 6 and 14 was lower in cows treated with UF compared with cows in the CON group (10.7 vs. 28% and 1.1 vs. 9.1%). The odds (95% confidence interval) for survival and remaining in the farm at study d 6 and 14 and at 30 and 100 DIM for cows in the UF treatment were 4.67 (1.38-15.8), 2.77 (1.25-6.10), 3.13 (1.22-8.02), and 2.82 (1.38-5.71) times the odds of cows in the CON group, respectively. The odds of AI until 150 DIM and the interval from calving to first AI were not different between the 2 treatments. However, pregnancy was affected by treatment; the odds (95% confidence interval) of pregnancy at the first AI, 150 DIM, and 300 DIM for cows treated with UF were 2.15 (1.05-4.40), 1.81 (1.04-3.15), and 1.92 (1.09-3.38) times the odds of cows in the CON group, respectively. Days to pregnancy were similar in both treatment groups, but the number of artificial inseminations per pregnancy were different (2.69 vs. 2.02 for cows in the CON and UF treatments). Results indicate that cows with TPM administered intrauterine infusion of Optimum UterFlush had higher odds of recovering and improved reproductive performance compared with cows treated with povidone iodine.

Factors associated with early cyclicity in postpartum dairy cows.

The objective of this study was to evaluate factors associated with resumption of ovarian cyclicity within 21 days in milk (DIM) in dairy cows. Cows (n=768) from 2 herds in north Florida had their ovaries scanned at 17±3, 21±3, and 24±3 DIM. Cows that had a corpus luteum ≥20mm at 17±3 or at 21±3 DIM or that had a corpus luteum <20mm in 2 consecutive examinations were determined to be cyclic by 21±3 DIM. The following information was collected for up to 14 DIM: calving season, parity, calving problems, metabolic problems, metritis, mastitis, digestive problems, lameness, body weight loss, dry period length, and average daily milk yield. Body condition was scored at 17±3 DIM. Multivariable mixed logistic regression analysis was performed using the GLIMMIX procedure of SAS. Variables with P≤0.2 were considered in each model. Herd was included as a random variable. Three models were constructed: model 1 included all cows, model 2 included only cows from dairy 1 that had daily body weights available, and model 3 included only multiparous cows with a previous dry period length recorded. In model 1, variables associated with greater cyclicity by 21±3 DIM were calving in the summer and fall rather than in the winter or spring, being multiparous rather than primiparous, and not having metabolic or digestive problems. In model 2, variables associated with greater cyclicity by 21±3 DIM were calving in the summer and fall, not having metritis or digestive problems and not losing >28 kg of BW within 14 DIM. In model 3, variables associated with greater cyclicity by 21±3 DIM were absence of metabolic problems and dry period ≤76 d. In summary, cyclicity by 21±3 DIM was negatively associated with calving in winter or spring, primiparity, metritis, metabolic or digestive problems, loss of >28 kg of body weight, and a dry period >76d. Strategies preventing extended dry period length and loss of BW, together with reductions in the incidence of metritis as well as metabolic and digestive problems should improve early cyclicity postpartum.

Dynamics of culling for Jersey, Holstein, and Jersey × Holstein crossbred cows in large multibreed dairy herds.

The objective of this observational study was to describe and compare the dynamics of reason-specific culling risk for the genetic groups Jerseys (JE), Holsteins (HO), and Jersey × Holstein crossbreds (JH), considering parity, stage of lactation, and milk yield, among other variables, in large multibreed dairy herds in Texas. The secondary objective was to analyze the association between survival and management factors, such as breeding and replacement policies, type of facilities, and use of cooling systems. After edits, available data included 202,384 lactations in 16 herds, ranging from 407 to 8,773 cows calving per year during the study period from 2007 to 2011. The distribution of lactation records by genetic group was 58, 36, and 6% for HO, JE, and JH crosses, respectively. Overall culling rates across breeds were 30.1, 32.1, and 35.0% for JH, JE, and HO, respectively. The dynamics of reason-specific culling were dependent on genetic group, parity, stage of lactation, milk yield, and herd characteristics. Early lactation was a critical period for "died" and "injury-sick" culling. The risk increased with days after calving for "breeding" and, in the case of HO, "low production" culling. Open cows had a 3.5 to 4.6 times greater risk for overall culling compared with pregnant cows. The odds of culling with reason "died" within the first 60 d in milk (DIM) were not significantly associated with genetic group. However, both JE and JH crosses had lower odds of live culling within the first 60 DIM compared with HO cows (OR=0.72 and 0.82, respectively). Other cow variables significantly associated with the risk of dying within the first 60 DIM were cow relative 305-d mature equivalent (305ME) milk yield, parity, and season of calving. Significant herd-related variables for death included herd size and origin of replacements. In addition to genetic group, the risk of live culling within 60 DIM was associated with cow-relative 305ME milk yield, parity, and season of calving. Significant herd-related variables for live culling included herd-relative 305ME milk yield, herd size, type of facility, origin of replacement, and type of maternity. Overall, reason-specific culling followed similar patterns across DIM in the 3 genetic groups.

Inducing ovulation early postpartum influences uterine health and fertility in dairy cows.

The objective of the current study was to evaluate the effect of GnRH early postpartum on induction of ovulation, uterine health, and fertility in dairy cows. Holstein cows without a corpus luteum (CL) at 17 ± 3 DIM were assigned randomly to receive i.m. GnRH (n = 245) at 17 ± 3 and 20 ± 3 DIM or remain as controls (n = 245). Ovaries were scanned by ultrasonography twice weekly totaling 4 examinations. Ovulation was characterized by the appearance of a CL ≥ 20 mm at any ultrasound or CL <20mm in 2 consecutive examinations. Clinical and cytological endometritis were diagnosed at 35 DIM. Compared with control, GnRH increased ovulation up to 3.5d after the last treatment (78.7 vs. 45.0%) and did not affect the prevalence of clinical endometritis (23.9 vs. 18.6%) or cytological endometritis (30.9 vs. 32.8%). Prevalence of clinical endometritis increased in cows that had calving problems (32.6 vs. 15.9%) and metritis (40.6 vs. 15.8%). Metritis increased prevalence of cytological endometritis (50.7 vs. 23.5%). Treatment with GnRH did not affect pregnancy per artificial insemination at 32 (37.6 vs. 38.6%) or 74 d after artificial insemination (35.0 vs. 31.5%), but reduced pregnancy loss (6.8 vs. 18.1%). No overall effect of GnRH treatment on hazard of pregnancy was observed; however, an interaction between GnRH treatment and ovulation showed that GnRH-treated cows that ovulated had increased hazard of pregnancy by 300 DIM compared with GnRH-treated and control cows that did not ovulate (hazard ratio=2.0 and 1.3, respectively), but similar to control cows that ovulated (hazard ratio=1.1). Gonadotropin-releasing hormone early postpartum induced ovulation without affecting uterine health, but failed to improve pregnancy per artificial insemination or time to pregnancy, although it reduced pregnancy loss.

Mucosal immune responses in peri-parturient dairy cattle.

The objectives of this study were to evaluate mucosal immune responses in peripartum Holstein cows, to assess the impact of intranasal modified live viral (MLV) vaccination on mucosal immunity, and to explore the relationship between genotype and peripartum immune responses. Eighty multiparous Holstein cows were randomized to receive either: 1) intranasal MLV tri-valent viral vaccine 18-24 days prior to expected calving (DC); 2) the same vaccine within twelve hours after parturition (F); 3) vaccine at both time points (DCF), or 4) no vaccine (CON). Nasal secretions and sera were collected from all cattle pre-vaccination and on multiple days before and after calving to determine concentrations of interferon beta (IFN-beta) and IFN-gamma and bovine herpesvirus-1 (BHV-1-) and bovine respiratory syncytial virus (BRSV-) specific IgA in nasal secretions, and BHV-1 and BRSV serum neutralizing (SN) titers. Cows were genotyped by bead-based microarray, genotypes were used to categorize previously established health traits, and relationships between immune responses and genotype were evaluated. There was no significant effect of vaccination on immune responses, although all vaccinated groups demonstrated numerically increased IFN-gamma within four days post vaccination. There was a significant (P <0.0001) time effect on nasal IgA in CON, F, and DCF groups, with the highest nasal IgA titers measured post calving. There was a significant (P <0.0001) time effect on nasal IFN-beta in all groups. Significant relationships between genotype and immune response were not detected. Contrary to previous reports of systemic immunosuppression, bovine mucosal responses appear to be intact in the peripartum period.

Events occurring during the previous lactation, the dry period, and peripartum as risk factors for early lactation mastitis in cows receiving 2 different intramammary dry cow therapies.

The objective of this study was to investigate the association between mastitis events occurring during the previous lactation, the dry period, and the peripartum period on the incidence of early lactation mastitis in cows receiving ceftiofur hydrochloride or penicillin dihydrostreptomycin as intramammary dry cow antibiotic therapy. Cows (n=402) from 2 large dairy farms in Central Florida were enrolled in the study at the time of dry-off processing and were randomly assigned to 1 of 2 dry cow therapies: ceftiofur hydrochloride or penicillin dihydrostreptomycin. Composite milk samples were collected at dry-off and after calving for bacteriological examination and somatic cell count. Peripartal health disorders were monitored during the first 30 d of lactation and included calving difficulty, metritis, ketosis, and left displaced abomasum. Milk production and individual somatic cell scores (SCS) were recorded monthly by the Dairy Herd Improvement Association. The main outcome variables were the risk of clinical mastitis during the first 30 and 60 d of lactation, and the risk of subclinical mastitis at the first 2 monthly Dairy Herd Improvement Association tests after calving (up to 70 d in milk). Additionally, the SCS and the presence of mastitis pathogens in milk at dry-off and at calving were analyzed. Explanatory variables consisted of events occurring during the previous lactation, at dry-off and during the dry period, at calving, and within the first 30 d after calving. Multiple events occurring during the previous lactation had a significant effect on the incidence of mastitis in the subsequent lactation. These events included low milk yield, intermediate lactation length, clinical mastitis, and lactation SCS average. Similarly, intramammary infections with environmental bacteria at dry-off increased the chances of clinical mastitis the first month after calving. Dry-off therapy had a significant effect on mastitis incidence; cows treated with ceftiofur hydrochloride had lower odds of having clinical and subclinical mastitis in the subsequent early lactation compared with cows treated with penicillin dihydrostreptomycin.

Waiting time in the premilking holding pen and subsequent lying and walking behaviors of Holstein cows.

The objective of this study was to assess the effect of waiting time (WT) in the premilking holding pen on the subsequent lying and walking behaviors of Holstein cows. A total of 108 cows (multiparous n = 95; primiparous n = 13), milked 3 times/d [AM (0700 h), PM (1500 h), and nighttime (2300 h)] were monitored for individual WT, which was defined as the time elapsed between the entrance of the first cow to the milking stall in a rotary milking system and the entrance of each subsequent cow housed in the same milking pen. Data for lying time (min), standing time (min), lying bouts (no.), and walking behavior (no. of steps) in 15-min intervals were collected using a commercial 3-dimensional accelerometer affixed on the hind left leg of each cow from early to mid lactation. Mean values (min/h, no./h) for each behavior calculated between consecutive milkings were compared among 3 WT categories: cows with WT ≤30 min (WT1), WT 30 to 60 min (WT2), and WT >60 min (WT3). The overall mean (SD) of WT during the study period was 31.2 (23.4) min, and the distribution of WT1, WT2, and WT3 in all cows through the monitoring period was 50.9, 43.3, and 5.7%, respectively. No significant effects were established for overall WT on any of the behaviors under analysis. However, subsequent analysis by milking shift indicated that, during the period following the night milking, cows in WT1 exhibited the shortest lying time, whereas cows in WT3 had the greatest number of lying bouts. No effect of WT category was observed on the number of steps after any of the milking shifts. Results of this study indicate a moderate effect of WT on lying behavior after the nighttime milking. Variables such as temperature-humidity index, parity, and time of day affected cow behavior and should be considered when evaluating the impact of routine management practices, such as milking, on commercial farms.

Effect of days to conception in the previous lactation on the risk of death and live culling around calving.

The objective was to quantify the effect of days to conception (days open) in the previous parity on the risk of death and live culling (excluding the disposal reasons "dairy purposes" and "death") in the proximity of a subsequent calving in Holstein cows enrolled in the Dairy Herd Improvement program. After edits, 2,075,834 observations of cows calving between 2001 and 2007 in herds located in 36 US states primarily east of the Mississippi river were available. The period at risk included the time between 14 d before expected calving to 60 d after calving. Days open were categorized in 6 periods: 0 to 45 d, 46 to 90 d, 91 to 150 d, 151 to 210 d, 211 to 300 d, and 301 to 600 d after calving in the previous parity. Other variables of interest included parity, length of the dry period before calving, relative last test-day milk yield before dry off before calving, season of calving, and the cow's relative 305-d mature equivalent (305ME) milk yield before calving. Control variables were calving year, herd size, and relative herd 305ME milk yield. All variables were categorized. Generalized mixed models were used and included herd as random effect. Interactions between days open and the variables of interest were included in the models. Least squares means for the risk of death between -14 and 60 d after calving were 2.5, 2.5, 2.9, 3.6, 4.4, and 5.8% for increasing categories of days open. Similarly, for the same categories, least squares means for the risk of live culling were 4.5, 5.0, 5.4, 6.1, 6.9, and 8.1%. The effect of days open on the risk of death was slightly greater for third-parity cows, for long dry periods, for cows with low test-day milk yield before dry off before calving, for spring calvings, and for intermediate relative 305ME milk yield before calving. Similar trends for these interactions were found for the risk of live culling, except for relative 305ME milk yield before calving, where the effect of days open was more pronounced for high-producing cows. In conclusion, increased days open in the previous parity were associated with a greater risk of death and live culling around calving.

Reproductive risk factors for culling and productive life in large dairy herds in the eastern United States between 2001 and 2006.

Knowledge of reproductive risk factors for culling is useful in making insemination and culling decisions and helps motivate efforts to reduce or eliminate risk factors. The objective of this study was to describe survival and reproductive risk factors for culling in Holstein dairy herds with at least 200 cows. Results were calculated from 2,345,015 DHI lactation records from 727 herds with at least 200 cows from 2001 to 2006. Herds were located in 36 states primarily located east of the Mississippi River. Kaplan-Meier survival curves were obtained and daily hazards of culling were calculated with the actuarial method. Cox regression was performed with the GLIMMIX procedure in SAS (SAS Institute Inc., Cary, NC). The hazard of culling increased with parity number. Cows in their sixth parity had 3 times greater hazards than cows in their first parity. Medium remaining productive life for cows calving in parity 1 to 6 were 907, 697, 553, 469, 423, and 399 d, respectively. Daily hazards of culling first peaked approximately 30 d after calving and then again later in lactation, after 280 d, for older cows. Hazards for first-parity cows peaked earlier, around d 10 after calving, and the first-parity cows had lower risks of culling later in lactation than older cows. Pregnant cows had 3 to 7 times lower hazards of culling than open cows. Hazards of culling increased for cows that had greater calving difficulty, gave birth to males or twins, were in herds with shorter days to first insemination, or had longer days to conception. The possible to likely use of a synchronized breeding program increased from 21.9% in 2001 to 41.4% in 2006. Cows in herds that did not use a synchronized breeding program had slightly lower risks of culling than those in herds that at least possibly used a synchronized breeding program.

Dynamics of culling risk with disposal codes reported by Dairy Herd Improvement dairy herds.

The objective was to describe the dynamics of culling risk with disposal codes for Holstein dairy cows reported by herds enrolled in the Dairy Herd Improvement program. Dairy producers could report 1 of 9 possible disposal codes or forego reporting a code. After edits, 3,629,002 lactation records were available for cows calving between 2001 and 2006 in 2,054 herds located in 38 states primarily east of the Mississippi river. The distribution of culled cows by disposal code was estimated by parity, days after calving, pregnancy status, cow-relative 305-d mature equivalent milk yield, herd-relative 305-d mature equivalent milk yield, and season. Of all herds, 57% reported all 8 different disposal codes excluding the codes dairy purposes and reason not reported. Hazard (risk) functions were calculated by parity, from 1 to 520 d since calving for open cows and from 1 to 280 d since conception for pregnant cows. Annualized live culling rate and death rate (reported code was death) were 25.1 and 6.6%, respectively. The primary disposal code was died (20.6% of all culling), followed by reproduction (17.7%), injury/other (14.3%), and low production and mastitis (both 12.1%). The risk of culling with various disposal codes varied with stage of lactation. Died and reproduction were the most frequently reported codes for cows leaving the herd during early and late lactation, respectively. Early lactation was also a critical period for culling with the disposal codes injury/other and disease, and the risk increased with days after calving for the codes low production and reproduction. The risk of culling with the disposal code died showed the greatest seasonal pattern with increased risk of death in spring and summer. A negative association was found between annualized live culling and death rates within herds. Compared with open cows, pregnant cows had a lower risk of culling with all reported disposal codes. In addition, the risk of culling was lower in high-producing cows with all disposal codes. In conclusion, the risk for culling by disposal code varied by parity, stage of lactation, season, pregnancy status, and milk yield.

Use of milk electrical conductivity for the differentiation of mastitis causing pathogens in Holstein cows.

Mastitis is one of the most prevalent and costly diseases in dairy cattle. Key components for adequate mastitis control are the detection of early stages of infection, as well as the selection of appropriate management interventions and therapies based on the causal pathogens associated with the infection. The objective was to characterize the pattern of electrical conductivity (EC) in milk during intramammary infection, considering specific mastitis-causing pathogen groups involvement. Cows (n = 200) identified by an in-line mastitis detection system with a positive deviation ≥15% in the manufacturer's proprietary algorithm for EC (high electrical conductivity (HEC)) were considered cases and enrolled in the study at the subsequent milking. One control (CON) cow, within normal ranges for EC, was matched to each case. A composite milk sample was collected aseptically from each cow for bacteriological culture. Milk yield (MY) and EC were recorded for each milking during ±7 days relative to enrollment. Milk cultures were categorized into gram positive (GP), gram negative (GN), other (OTH) and no growth (NOG). Data were submitted for repeated-measures analysis with EC as the dependent variable and EC status at day -1, bacteriological culture category, parity number, stage of lactation and days relative to sampling as main independent variables. Average (± standard error (SE)) EC was greater in HEC than in CON cows (12.5 ± 0.5 v. 10.8 ± 0.5 mS/cm) on the day of identification (day -1). Milk yield on day -1 was greater in CON than in HEC (37.6 ± 5.1 v. 33.5 ± 5.2 kg). For practical management purposes, average EC on day -1 was similar for the different bacteriological culture categories: 11.4 ± 0.6, 11.7 ± 0.5, 12.3 ± 0.8 and 11.7 ± 0.5 mS/cm in GN, GP, OTH and NOG, respectively. Parity number was only associated with day -1 EC in HEC group, with the greatest EC values in parity 3 (12.3 ± 0.3 mS/cm), followed by parity 2 (11.9 ± 0.2 mS/cm), parity >3 (11.6 ± 0.5 mS/cm) and primiparous cows (11.2 ± 0.2 mS/cm). An effect on EC for the interaction of day relative to identification by pathogen gram category was observed. The same interaction effect was observed on daily MY. Overall, the level of variation for MY and EC between- and within-cows was substantial, and as indicated by the model diagnostic procedures, the magnitude of the variance in the cows in the CON group resulted in deviations from normality in the residuals. We concluded that characteristic temporal patterns in EC and MY in particular pathogen groups may provide indications for differentiation of groups of mastitis-causing pathogens. Further research to build detection models including EC, MY and cow-level factors is required for accurate differentiation.

A randomized controlled clinical trial on the effect of acupuncture therapy in dairy cows affected by pyometra.

Pyometra (PYO) is a reproductive disease characterized by the accumulation of purulent or mucopurulent material within the uterine lumen, in the presence of an active corpus luteum (CL). As the CL continues secreting progesterone, PYO would develop following endometritis. Due to prohibited use of artificial luteolytic hormones in US certified organic dairies, conventional therapies consisting of administration of prostaglandin F2α, are not applicable. The objective of this study was to evaluate the efficacy of two acupuncture procedures on the treatment of persistent CL in cows with PYO. We hypothesized that acupuncture would reduce CL diameter and serum progesterone (P4) concentrations, leading to regression of PYO. Holstein cows with PYO, at an USDA certified organic dairy farm in Northern Colorado, were enrolled in a randomized controlled clinical trial and assigned to 1 of 3 treatments: (1) control pyometra (CP; no treatment; n = 17); (2) electroacupuncture (EAP; n = 15); and (3) laser acupuncture (LAP; n = 15). Each cow received three 9-min (EAP) or 20-min (LAP) acupuncture sessions in alternate days. All study cows had blood samples collected for determination of serum progesterone concentration at d0, and at d2, d4, d11, d18, and d25 after first treatment. The ovaries were scanned by transrectal ultrasonography at -3d, d0, d2, d4, d11, and d18 to determine the diameter of the CL. The effect of treatment in the outcome variables was evaluated by ANOVA and by repeated measures analyses, accounting for baseline data (CL diameter and progesterone serum concentration). Average ± SE change in CL diameter from d0 to d18 were 0.94 ± 1.0 mm, 0 ± 1.0 mm, and - 0.33 ± 1.0 mm for CP, EAP, and LAP, respectively. The repeated measures analysis indicated no significant differences for CL diameter among groups. None of the study cows had serum progesterone values <1 ng/ml by the end of the monitoring period (d25) and average ± SE change from d0 to d25 were - 4.0 ± 1.97 ng/ml, -0.76 ± 2.1 ng/ml, and 3.24 ± 1.9 ng/ml for CP, EAP, and LAP, respectively. The repeated measures analysis indicated no significant differences for serum progesterone concentrations among groups. On farm cow records reviewed 150 d after treatment indicated that 2 cows in EAP and 1 cow in LAP conceived 38 d, 68 d, and 38 d, after treatment completion. In conclusion, acupuncture was not an effective treatment for persistent CL in cows with PYO, during the monitoring period.

Efficacy of non-antibiotic treatment options for digital dermatitis on an organic dairy farm.

The objective of this study was to evaluate the efficacy of two non-antibiotic treatment options for digital dermatitis (DD) on an organic certified dairy farm. A randomized clinical trial was conducted using 70 multiparous Holstein cows with an early DD lesion at a USDA certified organic dairy farm in Northern Colorado, USA. Cows were enrolled in the study based on the presence of early DD lesions (scores M1 and M2) and randomly assigned to one of three treatments: (1) topical application of copper sulfate and iodine (CUI); (2) topical application of honey and iodine (HOI); and (3) control subject to no treatment (CON). Cows were evaluated at enrolment and on days 3, 12, 28, and 120 post treatment for pain and lesion size and received a locomotion and a lesion score. Cure was defined as the transition from active to non-active stages (M1/M2 to M0 or M4). The formulations had variable effects on the treatment of DD. The cure rate was numerically higher for CUI on all follow up days. The proportion of cows experiencing pain on d3 after treatment was greater in CON, followed by HOI and CUI. However, this proportion increased in HOI during the follow up period. The CUI group had a greater reduction in lesion size and larger lesions persisted in HOI. Non-antibiotic treatment formulations were partially effective in the treatment of DD in organic dairy cows: The two non-antibiotic formulations resulted in an earlier transition to mature lesions compared with the control group. The CUI combination was the most effective treatment in reducing lesion size, pain, and lameness in affected cows. However, this combination had short-term efficacy, which did not persist throughout the duration of the study. The HOI combination produced only transient reduction in lesion size.

Effect of high somatic cell counts on reproductive performance of Chilean dairy cattle.

The objectives were to evaluate the effect of high linear somatic cell counts (LNSCC > or =4.5) during early lactation on reproductive performance and to estimate their association with the risk of abortion in a population of central-southern Chilean dairy cattle. The analysis included records from a population of 157 farms and considered 1,127,405 test-day records including 101,944 lactations that began between 1997 and 2006. After data edits, the analyses of calving to first service and calving to conception intervals consisted of 88,633 and 70,877 lactations, respectively. Once controlling for significant variables, time to first breeding was 21.8 d longer in cows with at least 1 high LNSCC before the first breeding compared with controls. Cows with at least 1 high LNSCC before the fertile breeding had an increment in time to conception of 48.7 d and required, on average, 0.49 more services to conceive. The odds of conception at first service in cows with a high LNSCC within 30 d before [after] breeding were 0.85 (0.81 to 0.89; 95% confidence interval ) [0.82 (0.78 to 0.87; 95% confidence interval)] times the odds of conception for cows without a high LNSCC during that period. The Cox proportional hazard model indicated that after correction by calving year, lactation number, and milk yield standardized to 305 d, the risk of pregnancy decreased by 44% if a high LNSCC occurred before breeding. Cows registering a high LNSCC during the first 90 d of gestation had an increased risk of abortion, being 1.22 (1.07 to 1.35; 95% confidence interval) times more likely to abort than nonaffected cows. It is concluded that subclinical mastitis, measured as LNSCC >/=4.5, had a significant effect on reproductive performance in Chilean dairy cattle.

Rumination time and monitoring of health disorders during early lactation.

The objective was to evaluate the association between changes in daily rumination time (dRT) and early stages of disease during early lactation and to assess the performance of two proposed disease detection indices. This cohort study included 210 multiparous Holstein cows at the University of Florida Dairy Unit. Cows were affixed with a neck collar containing rumination loggers providing rumination time. The occurrence of health disorders (mastitis, metritis, clinical hypocalcemia, depression/dehydration/fever (DDF), digestive conditions, lameness and clinical ketosis) was assessed until 60 days in milk. Two indices were developed to explore the association between dRT and disease: (i) Cow index (CIx), based on changes in dRT in the affected cow during the days before the diagnosis of health disorders; (ii) Mates index (MIx), index based on deviations in dRT relative to previous days and healthy pen mate cohorts. Subsequently, an alert model was proposed for each index (ACIx and AMIx) considering the reference alert cut-off values as the differences between average index values in healthy and sick cows for each specific disease. The sensitivity (SE) of ACIx detecting disease ranged from 42% (digestive conditions and DDF) to 80% (clinical hypocalcemia) with 84% specificity (SP). The SE of AMIx ranged from 46% (digestive conditions and DDF) to 100% (clinical hypocalcemia) with 85% SP. Consistent reductions in rumination activity, both within cow and relative to healthy mate cohorts, were observed for each health disorder at the day of diagnosis. However, the ability of the proposed algorithms for detecting each specific disease was variable.