Dairy Herd Management Research Articles

137 DIFFERENCES IN EMBRYO PRODUCTION BETWEEN LACTATING AND NON-LACTATING HOLSTEIN DONOR COWS

Embryo transfer is a common practice in reproductive management of large dairy herds. Data from 2 dairies in the San Joaquin Valley in California (5000 lactating Holstein producing 27 500 pounds of milk in 365 days) was used to evaluate the differences in embryo production between lactating (105.3 ± 24.6 pounds of milk/day, 161 ± 85 days in milk and 3 ± 1 lactations) and nonlactating donor cows, from July 2006 to June 2007. Cows were observed daily for estrous signs and superovulation treatment was initiated 10 d later. Cows received FSH twice a day during 4 days in decreasing doses. On the fifth treatment of FSH, cows received an injection of PGF2α and 48 h later an injection of GnRH. Cows were inseminated 12 and 24 h after the GnRH injection. Uterine flush was performed 7 d after the first AI only in cows that had 2 or more CL. The total number of ova/embryos, viable embryos (transferred fresh or frozen), degenerated, and unfertilized structures were recorded (classified according to the guidelines of IETS). A Bernoulli regression model was fitted using the R software (www.r-project.org) for the variable superovulation response and the covariates were cow condition (lactating or nonlactating), season, and interactions. From 719 superovulated cows, 668 were flushed (92.9%): 86.8% (309/356) of the lactating cows and 98.9% (359/363) of the nonlactating cows (P < 0.01). There was evidence of season effect (P = 0.09). Cows tended to respond less to superovulation treatment during summer and fall. A negative binomial regression model was fitted to the response variables total number of ova/embryo and viable embryos and the covariates were cow condition, season, and interactions. Lactating cows produced fewer (6.77) ova/embryos than nonlactating cows (14.14; P < 0.01). The adjusted means were 5.93 v. 12.53 for fall, 6.30 v. 13.32 for winter, 8.24 v. 17.40 for spring and 6.32 v. 13.34 for summer, for lactating and nonlactating cows, respectively. Cows produced more ova/embryos during spring (P < 0.01). Less viable embryos were recovered from lactating cows (3.62) than nonlactating cows (5.44; P < 0.01). The adjusted means were 2.52 v. 3.98 for fall, 3.61 v. 5.69 for winter, 4.51 v. 7.12 for spring and 3.37 v. 5.31 for summer, for lactating and non lactating cows, respectively. The production of viable embryos in fall was different from winter and spring (P < 0.01). Lactating cows responded less to superovulation treatment and produced less viable embryos than nonlactating cows, probably because of the increased metabolism due to milk production. Warmer seasons were associated with lower viable embryo production. It is important to have a group of nonlactating donors to increase embryo production in large ET programs.

Short Communication: Scoring of Digital Dermatitis During Milking as an Alternative to Scoring in a Hoof Trimming Chute

Digital dermatitis is a serious problem in dairy production in many countries. In many settings, it is important to evaluate the digital dermatitis status of individual cows or an entire dairy herd. Such an evaluation has traditionally been done in a hoof trimming chute. An evaluation in the milking parlor can take place without disturbing the cows to a large extent, it can be done using less labor compared with an evaluation in a hoof trimming chute, and is cheaper than using a chute. The objective was to evaluate the sensitivity and specificity of a rapid screening method for digital dermatitis in the milking parlor, without using any specialized tools and taking approximately 15 s/cow. All lactating cows in 3 commercial Danish dairy herds were included. Cows were first scored for the presence of digital dermatitis during milking and the next day all cows were scored during hoof trimming. A 6-point nominal scoring system based on a visual inspection of the digital dermatitis lesions was used. For the analysis, the scores were dichotomized (digital dermatitis positive or digital dermatitis negative). Additionally, lesions were classified as small (diameter≤2cm) or large (diameter >2cm). Sensitivity and specificity were calculated using observations from the hoof trimming chute as the “gold standard” and observations during milking as the diagnostic test. Relatively large variation was found between herds with an overall sensitivity of 0.65 (95% confidence interval: 0.59 to 0.72) and a specificity of 0.84 (0.81 to 0.87). The sensitivity increased to 0.69 (0.62 to 0.76), when only large lesions were assessed. The method has several advantages compared with evaluation in a chute and may be a useful tool in the daily hoof health management in dairy herds.

Seasonal changes of CLA isomers and other fatty acids of milk fat from grazing dairy herds in the Azores

AbstractBACKGROUND: Season of the year associated with dietary changes has been recognized as a factor implicated in milk fat fatty acid (FA) profile in dairy cows. However, a lack of information exists concerning cows grazing all year round as is practiced in the Azores, where cows are supplemented in winter with maize silage plus concentrates, while in spring the higher grass allowance only requires supplementation with concentrate. The main objective of this study was to detect any seasonal variation of FA profile of milk fat from milk sampled in bulk tanks of 12 Azorean dairy herds.RESULTS Compared to winter milk, milk fat from spring presented a higher proportion of CLA cis‐9,trans‐11 (14.3 versus 9.6 g kg−1 FA), C18:1 trans‐11 (32 versus 22 g kg−1 FA), C18:2 trans‐11,cis‐15 (3.7 versus 2.2 g kg−1 FA), CLA trans‐11,cis‐13 (0.34 versus 0.23 g kg−1 FA) and C18:3 n‐3 (5.7 versus 5.4 g kg−1 FA). The C18:2 n‐6/C18:3 n‐3 ratio was lower (P < 0.05) in spring. Branched‐chain FA, except the anteiso‐C15:0, were higher in spring, while odd‐chain FA (C15:0) were higher in winter.CONCLUSION: Dairy herd management in the Azores presents a seasonal variation of milk fat FA composition, where the spring milk may present increased potential benefits for human consumers. Copyright © 2008 Society of Chemical Industry

Beyond Equal: From Same But Different to the Doctrine of Substantial Equivalence

A same-but-different dichotomy has recently been encapsulated within the ill-defined concept of “substantial equivalence”. By invoking this concept the genetically modified organism (GMO) industry has escaped the rigors of safety testing that might otherwise apply. The curious concept of “substantial equivalence” grants a presumption of safety to GMO food. This presumption has yet to be earned, and has been used to constrain labelling of both GMO and non-GMO food. It is an idea that well serves corporatism. It enables the claim of difference to secure patent protection, while upholding the contrary claim of sameness to avoid labelling and safety scrutiny. It offers the best of both worlds for corporate food entrepreneurs, and delivers the worst of both worlds to consumers. The term “substantial equivalence” has established its currency within the GMO discourse. As the opportunities for patenting food technologies expand, the GMO recruitment of this concept will likely be a dress rehearsal for the developing debates on the labelling and testing of other techno-foods - including nano-foods and clone-foods.

Practical Ovsynch Programs

Reproductive efficiency is a major factor contributing to efficiency, profitability and sustainability of dairy farms. Estimates of economic loss due to reproductive inefficiencies range from $1 to 5 billion per year. Given the decreasing trend of conception rates during the past 30 years, it can be anticipated that fertility of lactating dairy cows will continue to be a paramount challenge to profitable dairy herd management. The exact physiological reasons for poor fertility of lactating dairy cows are unknown. This presentation focuses on correcting limitations of Ovsynch in addition to understanding the fertility potential of an ovulatory follicle by controlling its age, size, and function. Ovsynch can improve pregnancy rates when estrus detection rates are poor and inaccurate, leading to improper timing of artificial insemination in relation to ovulation. However, inadequate synchronization rate of Ovsynch limits its effectiveness. The focus of our research program is to determine if fertility of lactating dairy cows can be increased by modifying Ovsynch to control emergence of the ovulatory follicular wave and initiate ovulation at the prime stage of development of the synchronized ovulatory follicle. Our ultimate goal is to devise an exogenous hormonal control strategy using gonadotropin-releasing hormone (GnRH) and prostaglandin F2α (PGF2α) that reduces age, yet optimizes size and function, of the ovulatory follicle of Ovsynch. Based upon strong published data, it is our contention that control of ovulation to the first GnRH of Ovsynch, appropriate timing of luteolysis and the final GnRH-induced luteinizing hormone (LH) surge are essential for the synchronous emergence, development, and synchronized ovulation of the ovulatory follicle.

Use of Herd Solutions from a Random Regression Test-Day Model for Diagnostic Dairy Herd Management

In a random regression test-day model, environmental effects in addition to individual animal factors can be included and analyzed. Moreover, instead of herd-year classification of the management groups, the herd-test-day classification within the model better accounts for month-to-month short-term environmental variation in production and somatic cell count (SCC) traits. The herd management levels of milk yield (milk deviation from whole-country mean, kilograms/day), protein and fat concentration (protein and fat deviation, %), and SCC (SCC deviation, 1,000 cells/mL) are used in the dairy herd management Web application “Maitoisa” (in English, “Milky”). This management tool helps to recognize several management problems. For recognition of systematic patterns and single unusual test-days, a monthly time-trend analysis was developed to smooth the random fluctuations and display the yearly production pattern. In addition to analyzing single test-day deviations from the mean, modeled herd solutions assist users in identifying repeated phenomena and enable the forecasting of the management pattern for the subsequent year. The solutions are displayed either as tables or graphs plotted by calendar months. In addition to management effects of the farmer's own herd, he or she can request country or region percentiles to be displayed in the graphs. The Web service has been offered to farmers and dairy advisors since 2001, and it has proved to be a powerful tool for herd monitoring and planning.

Herd health and health management in organic versus conventional dairy herds in Norway

Earlier studies from Norway indicate that organic dairy farms enjoy better animal health than conventional dairy farms. However, these studies use veterinary treatment records and may not reflect the true health status since animal health may be handled differently, i.e. there might be different treatment schemes on organic versus in conventional farms. A study of animal health and health handling on both organic ( n = 149) and conventional ( n = 159) farms was performed based on information gathered from a mailed questionnaire merged with information from the Norwegian Cattle Health Services and the Norwegian Dairy Herd Recording System. Based on the original health records, there appeared to be many and large differences in herd health (veterinary) treatment parameters between the two production systems. However, after looking closer into the major diseases problems of mastitis, ketosis, and milk fever and converting from treatment to estimated case load based on questionnaire information about the observed differences in health handling, all that remained was a lower level of acute mastitis in organic dairy herds relative to conventional. When controlling for production level — milk yield being lower in organic herds — no difference between the two groups remained. We conclude that, based on official health records, there is an apparent difference in animal health performance which is mainly related to an observed difference in health management. The remaining difference in acute mastitis which is not explained by disease handling appears, at least in part, to be associated with a lower intensity of milk production. The impact of these findings in relation to animal welfare as a central issue in organic farming needs further investigations. Finally, the study demonstrates the need for a critical assessment of routinely collected health-related data used in research, in order to make valid inferences regarding animal health performance.

DairyVIP Program to Evaluate the Consequences of Changes in Herd Management and Prices on Dairy Farms

AN177, a 12-page illustrated fact sheet by Albert De Vries, explains some of the methods and describes the input and output sheets of DairyVIP, a computer program for dairy herd management. Published by the UF Animal Sciences Department, September 2006. AN177/AN177: The DairyVIP Program to Evaluate the Consequences of Changes in Herd Management and Prices on Dairy Farms (ufl.edu)

Milk yield, age at first calving, and the risk of BSE: An analysis at the farm level in France

The epidemic of bovine spongiform encephalopathy (BSE) in France, as in the UK, has affected dairy cattle much more than beef cattle. However, the intensification of dairy herd management as a risk factor for BSE has not to date been analyzed. For this purpose, two databases were merged: the French Milk Records database, and the French BSE database, which can be considered as being devoid of notification bias since July 2001, when systematic tests were implemented. Only pure Holstein herds were considered, which represent the vast majority of total and BSE-affected dairy herds in France. A case-control study was designed so that 20 control herds were matched to each case herd according to the location of the farm and the year of birth of the index case. Three thousand and forty five farms were included, among which 145 with a BSE case notified between July 2001 and July 2003, and 2900 controls. With respect to the risk of BSE, odds ratios for each class of milk yield and age at first calving were estimated by using conditional logistic regression models with appropriate adjustments to herd size. The two main results were the following: firstly, whereas most Holstein herds, with average production between 7000 and 10,000 kg, had nearly the same BSE risk, a small category of very intensive herds, with annual milk yields above 10,000 kg, were significantly more at risk than the other herds. Secondly, a very early first calving (under 26 months of age) was found to be at risk for BSE as compared to other categories, independently of the milk yield. These results are discussed in the light of the known age-dependent susceptibility to BSE.

Within- and Across-Person Uniformity of Body Condition Scoring in Danish Holstein Cattle

Body condition scores (BCS) are very useful for dairy herd management and breeding programs, but the consistency and quality of recordings made by consultants in the field are unknown. The objectives of this study were 1) to estimate the agreement in BCS within and among practicing dairy veterinarians and 2) to provide an indication of the effects of training and the value of calibration, and of what efforts need to be made to obtain a validity and precision in BCS adequate for management purposes. A total of 2,230 scores were recorded by 51 practicing dairy veterinarians and 6 highly trained instructors. The 6 instructors were cross-trained to validate calibration consistency in assigning BCS. Each individual scored approximately 20 cows twice, with the second scoring occurring approximately 2.5h after the first. Between the 2 recordings, the respective instructors conducted a training session for the practicing veterinarians using other cows. A weighted kappa coefficient was used to assess agreement among and within classifiers. Excellent agreement (kappa ≥0.86) was documented between repeated BCS recorded for the same cows by the highly trained instructors. In addition, the BCS provided by multiple classifiers from the instructor team appeared to be comparable across herds and classifiers. This legitimizes the use of BCS for benchmarking at both the cow and the herd level. The within-classifier and between-classifier kappa values were in the ranges of 0.22 to 0.75 and 0.17 to 0.78, respectively, in the group of practicing dairy veterinarians. Many of the veterinarians provided estimates of average BCS that differed considerably from the BCS recorded by the instructors. Between-classifier comparisons of herd BCS are not warranted unless a validation has been performed. If scores are collected by multiple classifiers with varying experience, a valid but imprecise estimate of the true population mean of BCS may be obtained if classifiers are inexperienced. The limited training effort used in this study seemed to have brought about substantial improvement in the validity and precision of the BCS determined by practicing veterinarians, compared with the BCS recorded on the same cows by highly trained classifiers.

Machine Learning as an aid to management decisions on high somatic cell counts in dairy farms

Abstract. High somatic cell counts (SCC) is associated with mastitis infection, in dairy herds, worldwide. This work describes Machine Learning (ML) techniques designed to improve the information offered to farmers on animals producing high SCCs according to particular herd profiles. The analysed population included 71 dairy farms in Asturias (Northern Spain) and a total of 2,407 lactating cows. Four sources of information were available: a) a questionnaire survey describing facilities, milking routines and management practices of the farms studied; b) dairy recording information; c) classification of the cows suspected of being healthy or subclinical mastitic according to farmers’ expertise; and d) positive or negative scores with respect to the California Mastitis Test (CMT). The decimal logarithm of the SCC (linear score), lactation number, herd size, lactating cows per milker, milk urea concentration, number of clusters per milker and actual SCC are shown to be the most informative attributes for mimicking both farmers’ expertise or CMT performance in order to identify animals producing persistently high SCCs in dairy herds. However, to improve the identification of cows suspected of being non-healthy, the system uses other information related to management and milking routines. Decision rules to predict CMT performance can provide useful, additional information to farmers to improve the management of dairy herds included in milk recording programs.

Dairy Management Practices Associated with Incidence Rate of Clinical Mastitis in Low Somatic Cell Score Herds in France

An epidemiological prospective study was carried out in French dairy herds with Holstein, Montbéliarde, or Normande cows and with low herd somatic cell scores. The objective was to identify dairy management practices associated with herd incidence rate of clinical mastitis. The studied herds were selected on a national basis, clinical cases were recorded through a standardized system, and a stable dairy management system existed. In the surveyed herds, mean milk yield was 7420kg/cow per yr and mean milk somatic cell score was 2.04 (132,000 cells/mL). Overdispersion Poisson models were performed to investigate risk factors for mastitis incidence rate. From the final model, the herds with the following characteristics had lower incidence rates of clinical mastitis: 1) culling of cows with more than 3 cases of clinical mastitis within a lactation; 2) more than 2 person-years assigned to dairy herd management; 3) balanced concentrate in the cow basal diet. Moreover, herds with the following characteristics had higher incidence rates of clinical mastitis: 1) milking cows loose-housed in a straw yard; 2) no mastitis therapy performed when a single clot was observed in the milk; 3) clusters rinsed using water or soapy water after milking a cow with high somatic cell count; 4) 305-d milk yield >7435kg; 5) herd located in the South region; 6) herd located in the North region; 7) cows with at least 1 nonfunctional quarter; and 8) premilking holding area with a slippery surface. The underlying mechanisms of some highlighted risk factors, such as milk production level and dietary management practices, should be investigated more thoroughly through international collaboration.

Development of a New Diagnostic Test for the Detection of Passively Acquired Immunoglobulin G 1 (IgG 1) in Newborn Calves Using Immunostick ELISA Technology

It is generally accepted that there is no transfer of immunity in utero in the bovine. The calf is dependent on ingestion and absorption of immunoglobulins (antibodies) from colostrum by the endothelial cells of the small intestine for protection against neonatal disease. Absorption of immunoglobulins (lg) is maximal at birth, declines rapidly and ceases by 24 hours post-partum. Because of modern dairy herd management practices worldwide, a high percentage of calves receive insufficient amounts of colostrum, and thus are deficient in protective antibodies and very susceptible to neonatal disease, particularly colisepticemia and diarrhea. Currently the level of immunity can be assessed by measuring the levels of lgG 1 in the blood, but these tests frequently must be conducted in a veterinary laboratory. Because of the lag time in obtaining a result, the calf is often already 24 hours old, immunoglobulin absorption has ceased and it is too late to correct the deficiency by feeding additional colostrum. This new test is non-invasive and measures the level of IgG 1 in nasal mucus. The test can be conducted on the farm, and takes 35 minutes to complete. If immunity is minimal, then the calf can be immediately fed colostrum to boost its immunity.

Efficacy of Ovsynch Program on Reproductive Performance in Dairy Cattle: A Meta-Analysis

The efficacy of the Ovsynch program in improving conception and pregnancy rates was compared with untreated controls and other synchrony programs in lactating dairy cows. This meta-analysis examined 71 treatment and control comparisons extracted from 53 research papers. Programs evaluated included Ovsynch, natural breeding, single, double, or triple prostaglandin injections, Select Synch, Heat Synch, and modified Ovsynch.Pregnancy rates for Ovsynch programs did not differ significantly from those with natural breeding programs [predicted Bayesian relative risk (RR) = 1.04, 95% Bayesian credible interval = 0.36 to 3.23]. Results of Ovsynch vs. PGF2α programs showed that the risk of conception (predicted Bayesian RR = 0.89, 95% Bayesian credible interval = 0.31 to 2.64), and pregnancy rates predicted Bayesian RR = 1.11, 95% Bayesian credible interval = 0.61 to 2.13) did not differ significantly between the Ovsynch group and cows in the PGF2α group. Comparisons between Ovsynch and Select Synch demonstrated that the risk of conception (predicted Bayesian RR = 0.94, 95% Bayesian credible interval = 0.52 to 1.59), and pregnancy rates (predicted Bayesian RR = 1.08, 95% Bayesian credible interval = 0.38 to 3.09) did not differ significantly between the 2 groups. Examination of Ovsynch vs. modified Ovsynch programs showed that the risk of pregnancy in cows synchronized with modified Ovsynch was similar to those treated with Ovsynch (predicted Bayesian RR = 0.89, 95% Bayesian credible interval = 0.71 to 1.12).Meta-analyses identified that the conception and pregnancy rates obtained with the prostaglandin, Select Synch, and modified Ovsynch (including presynch and CoSynch) programs were comparable with the Ovsynch program. Modifications to the Ovsynch program such as presynchronization and timed artificial insemination at the time of second GnRH injection (CoSynch) may be an alternative for reproductive management of dairy herds where detection of estrus is less than optimal. The findings of this study demonstrate that the Ovsynch program could benefit dairy operations because it allows for timed artificial insemination of lactating cows without detection of estrus. There was, however, little or no significant improvement in pregnancy rates using Ovsynch over other programs and the costs of labor and hormone administration should be considered when selecting this form of reproductive technology for routine use.

Associations between dairy herd management factors and bulk tank milk antibody levels against Ostertagia ostertagi

A cross-sectional questionnaire survey was performed on dairy herds in Flanders (Belgium) to detect management factors that are associated with an increased gastrointestinal parasite infection level of adult dairy cows. At the end of the grazing season, information concerning general herd factors, pasture management and anthelmintic treatment strategy was obtained from 956 herds. A bulk tank milk sample was obtained from 779 out of the 956 herds and the antibody levels (ODR) against Ostertagia ostertagi were determined. The associations between ODR and herd management factors were studied by two linear regression models. The first model evaluated the effect of general herd factors and the level of the cows’ exposure to pasture. Large sized herds had significantly lower ODRs as compared to medium ( P = 0.001) or small sized herds ( P = 0.03). Herds with only dairy cows had lower ODRs than herds with both dairy and beef cows ( P = 0.02). An increased exposure to pasture of the cows was associated with higher ODRs ( P < 0.001). The second model was built to evaluate the effect of pasture management factors and anthelmintic treatment strategy. Later turn-out on pasture ( P < 0.001) and mowing ( P = 0.002) were both significantly associated with lower ODRs. Cows that had a restricted grazing time per day tended to have lower ODR than cows that grazed 24 h per day ( P = 0.07). An increased exposure to pasture of the heifers was significantly associated with higher ODRs ( P = 0.001). No associations were found between ODR and calf related management factors, anthelmintic treatment strategy, time of turn-in, rotational grazing type or stocking rate. Later turn-out on pasture, mowing and restricting the grazing time per day are factors that can be applied immediately on dairy farms to reduce economical losses due to gastrointestinal nematodes.

Restoration patterns for luteinising hormone and ovarian function following treatment with GnRH agonist implants (deslorelin) for 7, 14 or 21 days in cycling dairy cows

Continuous GnRH agonist treatment of cows results in downregulation of GnRH responsiveness and a state of induced anoestrus. Inducing anoestrus in a precisely controlled manner could have several potential applications in dairy herd management. However, relatively little is known regarding the processes involved in restoring reproductive normality following an induced anoestrus. This study describes an experiment that was conducted to examine patterns of recovery of LH release and follicle growth in non-lactating Holstein cows immediately following cessation of treatment for 7, 14 or 21 days with a deslorelin implant. Oestrus cycles were synchronized at 7 days intervals and a deslorelin implant inserted in every cow 13 days after detected oestrus so that a group had implants for either 21 days ( n = 9), 14 days ( n = 10) or 7 days ( n = 9). On the day of implant removal every ovarian follicle greater than 4 mm in diameter was ablated using ultrasound guided vacuum needle aspiration in an attempt to standardize follicle sizes. Daily ovarian ultrasound examinations were performed on each cow until 35 days after implant removal and again at 45, 59 and 74 days. A subgroup of four cows randomly selected from each treatment group had frequent serial blood samples collected over 8 h at 4 and 10 days after implant removal for LH profiling. There was no significant effect of treatment duration on any LH parameter and results were pooled. Mean LH pulse amplitude increased by 67% between 4 and 10 days after implant removal (0.34 ng/ml versus 0.57 ng/ml; 4 days versus 10 days post-implant, P < 0.001). Mean pulse frequency remained unchanged between the two samplings (5.9 pulses versus 6.9 pulses per 8 h; 4 days versus 10 days post-implant, P > 0.1). Smoothed mean LH concentrations were unaffected by treatment duration or time (0.36 ng/ml versus 0.41 ng/ml; 4 days versus 10 days post-implant, P > 0.1). The pattern of follicle growth and ovulation did not differ significantly between treatment durations and pooled means were used for comparative descriptions. The emergence of a new follicle wave could be detected beginning at 4 days after implant removal (mean 7.9 ± 0.8 days). After emergence, a period of rapid follicle growth generally ensued with signs of oestrus occurring when the follicle reached 12.3 ± 0.5 mm and ovulation when mean follicle diameter was 13.1 ± 0.7 mm at 13.6 ± 1.5 days after implant removal. Oestrus preceded ovulation in all cases where ovulation subsequently occurred. The mean interovulatory interval after implant removal was similar amongst groups (18.2 ± 1.3 days). Follicle growth could be categorized into three groups based on the time to emergence and fate of the first wave DF. Spontaneous recovery was characterised by ovulation of the newly emerged DF. Failure to ovulate the first DF was associated with the formation of a persistent follicle by 35 days after implant removal with some 25% (7/28) of cows showing persistent follicles. Delayed emergence (>14 days after implant removal) was detected in 11% (3/28) of cows, but when a follicle did eventually emerge it was seen to ovulate normally. The correlation between number of days to first oestrus expression and LH pulse amplitude on 4 days post-implant removal was significant ( R 2 = 44%, P < 0.05). A model was then proposed for the restoration of reproductive function following GnRH agonist removal. In conclusion, duration of deslorelin treatment was associated with only small changes in LH and follicle parameters. The formation of persistent follicles delayed the recovery of more cows than delayed emergence of a new follicle wave after implant removal.

Rumen healthcare in the dairy cow

DRAMATIC increases in milk yields in recent decades have created challenges in terms of the dietary management of dairy herds. New feeding systems, which aim to satisfy the energy requirements...

Körperkondition und Stoffwechselstabilität als Grundlage für eine hohe Milchleistung bei ungestörter Fruchtbarkeit und allgemeiner Gesundheit von Milchkühen

Abstract. Title of the paper: Body condition and metabolic stability as basis of high milk yield, reproductive performance, and general health in dairy cows The target of this study was to describe the interactions between body condition and various descriptors of yield and fertility. It was aimed to identify an optimal conditional range to be used in herd management which combines high milk yield with acceptable fertility traits and general health. For this purpose, backfat thickness was measured by ultrasound at 46111 dairy cows on 78 different farms and was subsequently related to production variables. Negative energy balance is getting more intense and prolonged with increasing milk yield. However a conditional nadir below 10 mm leads to decreased milk production. To reach a high production level without an increasing incidence of health disorders, conditional nadir should not decline below 13 mm backfat thickness on herd average. Lower value only lead to negligibly higher milk yield but cause a distinctively higher risk of fertility problems and culling. High herd yields do not have to be at expense of reproduction performance and can be achieved without extreme body condition losses. An efficient herd management can offset depression in fertility, which commonly is combined with increasing milk yield. It is suggested a standard curve for backfat thickness throughout lactation to be used in dairy herd management.

Effect of prostaglandin E 2, dl-cloprostenol, and prostaglandin E 2 in combination with d-cloprostenol on uterine motility during diestrus in experimental cows

Prostaglandin F 2α is used in dairy herd management because of its luteolytic properties and for its direct effect on the myometrium in cows diagnosed with endometritis. Prostaglandin E 2 has a contractile effect on the bovine uterus. In human medicine, prostaglandin E 2 is routinely used to maintain labor and to ripen the cervix. We hypothesized, that a combination of prostaglandin F 2α and prostaglandin E 2 would provoke a long-lasting increase in intrauterine pressure (IUP) and uterine motility as compared to either prostaglandin group. Intrauterine pressure was recorded during the diestrus of eight lactating dairy cows using a transcervically placed intraluminal pressure microtransducer. After recording of physiologic uterine motility for 30 min, prostaglandins ( dl-cloprostenol, PGE 2, PGE 2 in combination with d-cloprostenol) or placebo were administered, followed by a 2 h recording period. Significant differences were found for the area under the curve, the mean amplitude and the intrauterine pressure, whereas the number of pressure waves did not differ significantly among treatments. Peak values for area under the curve and mean amplitude were found during the first 15 min for the combination of PGE 2 and d-cloprostenol. During the last 15 min of the recording session, area under the curve and mean amplitude were increased only for the combination of PGE 2 and d-cloprostenol as compared to placebo. Although PGF 2α and PGE 2 provoke an increase in intrauterine pressure, only their combination guarantees a significant effect over a 2 h recording period.

A Partnership of Universities and Agri-Business for an Effective Dairy Herd Management Learning Experience for Undergraduates: The Dairy Challenge

The Dairy Challenge contest allows undergraduate students to apply knowledge gained in the classroom in an evaluation of the management practices of commercial dairy farms. University faculty partnered with industry representatives to develop the competition. Participants in the Dairy Challenge do the following: 1) critically evaluate dairy herd management practices and make recommendations for improvements; 2) visit local dairy farms and gain knowledge of different farms’ management practices; 3) meet and interact with potential employers from the dairy industry during the contest; 4) evaluate herd records and utilize knowledge of dairy herd management software and computer presentation tools; 5) test their speaking, presentation, and problem-solving skills; and 6) work as a team to build consensus and tag-team speaking formats. Teams of four undergraduate students critically evaluate a commercial dairy farm using herd records, a description of farm operations, and tour of the farm facilities. The farmer answers questions pertaining to management of the farm in a group interview with all teams and in a separate interview with each individual team. Teams give a 20-min presentation that is scored on the description and assessment of the management practices and recommendations for improvements in management and facilities. Additionally, scoring is based on apparent level of preparation, speaking, presentation skills, and responses to judges’ questions. The judges are university specialists and dairy industry professionals. This capstone experience allows students to interact with dairy farmers and representatives from the dairy industry and expands their knowledge and skills gained during their academic career.