Effect of disease on reproduction in the dairy cow: a meta-analysis

Prevalence and molecular characterization of fluoroquinolone resistance in Escherichia coli isolates from dairy cattle with endometritis in China

Fluoroquinolones are frequently used to treat infectious disease that is caused by Escherichia coli in dairy cattle. However, fluoroquinolone resistance occurs and is due either to chromosomal mutations in the bacterial topoisomerase genes and/or to plasmid-mediated resistance genes. The purpose of this study was to determine the prevalence and molecular characteristics of fluoroquinolone resistance determinants in E. coli strains (n=148) isolated from dairy cattle with bovine endometritis in Inner Mongolia (China). Analysis of the mutations in the quinolone resistance-determining regions of resistant E. coli isolates confirmed previously reported substitutions in the GyrA and ParE. However, we identified additional substitutions in the ParC and GyrB that have not been reported earlier. No plasmid-mediated quinolone resistance genes in any of the isolates were found. The number of point mutations found per isolate correlated with an increase in the minimum inhibitory concentration of ciprofloxacin. Overall, 45.5% of the isolates were positive for the class I integrase gene along with four gene cassettes that were responsible for resistance to trimethoprim (dfr1 and dfrA17) and aminoglycosides (aadA1 and aadA5), respectively. The prevalence of extended-spectrum β-lactamases (ESBLs) was 100%, and the blaTEM gene was predominant in all of the isolates. In conclusion, our results identify the mechanism of quinolone resistance for the first time and reveal the prevalence of integron and ESBLs in E. coli isolates from dairy cattle with bovine endometritis in China after 20 years of quinolone usage in cattle.

Associations among serum pro- and anti-inflammatory cytokines, metabolic mediators, body condition, and uterine disease in postpartum dairy cows

BACKGROUND

Adipose tissue is an active endocrine organ which secretes a wide range of hormones and protein factors, collectively termed adipokines. Adipokines affect appetite and satiety, glucose and lipid metabolism, inflammation and immune functions. The objectives were to evaluate serum concentrations of adipokines (adiponectin, leptin, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6) in lactating dairy cows with postpartum uterine inflammatory conditions (metritis, clinical endometritis or subclinical endometritis) and in cows experiencing loss of body condition, and to assess the relationship of adipokines and body condition loss in the establishment of persistent uterine inflammatory conditions.

METHODS

Lactating multiparous Holstein cows (N = 40), with body condition scores (BCS) from 2 to 4 (eight cows for each 0.5 score increment) were enrolled. Body condition was monitored for all cows weekly for 7 weeks post calving; cows with uterine inflammatory conditions were also re-evaluated 2 weeks later. Blood samples were collected from 1 week prior to calving to 7 weeks after calving for determination of serum concentrations of adipokines, insulin and insulin like growth factor (IGF)-1.

RESULTS

Cows with metritis or clinical endometritis had higher serum concentrations of adiponectin, leptin, TNF-alpha, IL-1beta and IL-6 compared to normal cows (P < 0.05). Furthermore, serum leptin, TNF-alpha, IL-1beta and IL-6 were higher in cows with subclinical endometritis compared to normal cows (P < 0.05), and insulin and IGF-1 concentrations were lower in cows with metritis or clinical endometritis. Cows with low BCS (2 and 2.5) had significantly higher adiponectin, TNF-alpha, IL-1beta and IL-6 than those with high BCS (3 to 4). Cows with persistent uterine inflammatory conditions had higher adiponectin, leptin TNF-alpha, IL-1beta and IL-6 and insulin compared to normal and spontaneously recovered cows, except for IGF-1 (P < 0.05).

CONCLUSIONS

Serum concentrations of adipokines, insulin, and IGF-1 had significant associations with BCS categories (low vs. high) and postpartum uterine inflammatory conditions. Perhaps loss of body condition mediated increases in anti- and pro-inflammatory cytokines, whereas increased pro- and anti-inflammatory cytokines concentrations mediated body condition loss and thereby prolonged persistence of uterine inflammation in dairy cows.

The plasminogen activator system in the ovine placentome during late gestation and stage-two of parturition

The process of placental separation is not completely understood. In domestic animals, especially cattle, it is important that expulsion of the fetal membranes takes place in a timely manner in order to achieve maximal reproductive efficiency. The activity of the matrix-metalloprotease (MMP) family of proteases is known to be reduced in placentomes from cases of retained placenta. Members of the MMP family are known to be activated by the plasminogen activator (PA) family of proteases. We hypothesized that the expression and activity of the PA family increase in the cotyledon and/or caruncle as parturition approaches, with maximal expression and activity at parturition. To test this hypothesis, we performed reverse-transcriptase quantitative PCR and plasminogen-casein zymography to detect the presence and activity of PA family members in the placentome leading up to and during parturition in spontaneous and dexamethasone-induced parturient ewes. The results from our experiments indicated that serine proteases inhibitor E1 (SERPINE1) mRNA abundance in the cotyledon was different between treatment groups (P = 0.0002). In the caruncle, gene expression for plasminogen activator urokinase-type (PLAU) was different (P = 0.0154), and there was a strong trend for differences in SERPINE1 expression (P = 0.0565). These results demonstrate that expression of the PA system in the placentome changes from late pregnancy to parturition, and the presence or activity of these enzymes may occur after fetal expulsion.

Metritis in dairy cows: risk factors and reproductive performance

The objectives of this study were to assess the risk factors for metritis, its effects on milk yield and on reproductive performance, and the efficacy of ceftiofur therapy in Holstein dairy cows. Cows (n=303) from a commercial dairy herd in Argentina were studied. Cows were scored for body condition, and blood samples were collected on d -14, 7, 21, 31, 41, and 50 relative to parturition. Cows having a watery, purulent, or brown, and fetid vaginal discharge (VD) and rectal temperature ≤ 39.2°C were diagnosed as having clinical metritis, and those having a similar VD and rectal temperature >39.2°C were diagnosed as having puerperal metritis. Both clinical and puerperal metritis cows were randomly assigned to control (no treatment) or ceftiofur group (2.2mg/kg×3 consecutive days). Cure was declared if clear VD was observed at 21 d in milk (DIM). Blood samples were analyzed for nonesterified fatty acids, β-hydroxybutyrate, and blood urea nitrogen using commercial kits, and for insulin-like growth factor-1, insulin, and leptin by RIA. Data were analyzed with PROC MIXED, GENMOD, PHREG, and LIFETEST from SAS (SAS Institute Inc., Cary, NC). The risk for metritis increased with dystocia, retained fetal membranes, and dead calf [AOR (adjusted odds ratio)=2.58, 95% CI: 1.189-5.559], and as prepartum nonesterified fatty acids levels increased (AOR=1.001, 95% CI: 0.999-1.002). Conversely, risk decreased as prepartum insulin-like growth factor-1 increased (AOR=0.65, 95% CI: 0.349-1.219). Cows having either clinical or puerperal metritis produced less milk by 90 DIM than did healthy cows (2,236 ± 172 vs. 2,367 ± 77 vs. 2,647 ± 82 kg, respectively). Cows with puerperal metritis had lower risk for pregnancy by 100 DIM (AOR=0.189, 95% CI: 0.070-0.479) and a lower hazard rate for pregnancy by 150 DIM (hazard rate: 0.753, 95% CI: 0.621-0.911), and took longer to get pregnant (129 vs. 111 vs. 109 d, for puerperal metritis, clinical metritis, and healthy cows, respectively). Ceftiofur treatment was not associated with cure rate or milk yield but was related to increased risk for pregnancy at timed artificial insemination (AOR=2.688, 95% CI: 0.687-10.832), and for lower risk of reproductive cull (AOR=0.121, 95% CI: 0.014-1.066). In conclusion, abnormal calving and negative energy balance are associated with increased risk for metritis. Metritis, especially puerperal metritis, correlates with reduced milk production and poor reproductive performance. Finally, the likelihood for having a normal VD (indicative of cure) increased 2.6% for every day of increase in postpartum time and was 2 times higher for cows with clinical metritis than for those with puerperal metritis.

Therapy of bovine endometritis with prostaglandin F2α: a meta-analysis

The objective of the conducted meta-analysis was to assess the efficacy of the treatment of bovine endometritis with PGF(2α) by statistical means. Postpartum uterine infections have a high prevalence and a very negative effect on reproductive performance in dairy cattle. Because of a wide discordance between research results, a meta-analysis of the efficacy of the treatment of bovine endometritis with PGF(2α) was conducted. A comprehensive literature search was performed using online databases to reveal a total of 2,307 references. In addition, 5 articles were retrieved by reviewing citations. After applying specific exclusion criteria and evaluating specific evidence parameters, 5 publications, comprising 6 trials, were eligible for being analyzed by means of meta-analysis. Data for each trial were extracted and analyzed using meta-analysis software Review Manager (version 5.1; The Nordic Cochrane Centre, Copenhagen, Denmark). Estimated effect sizes of PGF(2α) were calculated on calving to first service and calving to conception interval. Prostaglandin F(2α) treatment of cows with chronic endometritis had a negative effect on both reproductive performance parameters. Heterogeneity was substantial for calving to first service and calving to conception interval [I(2) (measure of variation beyond chance)=100 and 87%, respectively]; therefore, random-effects models were used. Sensitivity analysis as well as subgroup analysis showed that the performance of randomization was influential in modifying effect size of PGF(2α) treatment. The funnel plot illustrated a publication bias toward smaller studies that reported a prolonged calving to conception interval after a PGF(2α) treatment. We conclude that the investigation of this subject by means of meta-analysis did not reveal an improvement of reproductive performance of cows with endometritis after treatment with PGF(2α). Furthermore, there is a shortage of comparable high quality studies investigating reproductive performance after PGF(2α) treatment of cows with chronic endometritis.

Heritable and non-heritable genetic effects on retained placenta in Meuse-Rhine-Yssel cattle

Failure of the timely expulsion of the fetal membranes, called retained placenta, leads to reduced fertility, increased veterinary costs and reduced milk yields. The objectives of this study were to concurrently look at the heritable and non-heritable genetic effects on retained placenta and test the hypothesis that a greater coefficient of relationship between dam and calf increases the risk of retained placenta in the dam. The average incidence of retained placenta in 43,661 calvings of Meuse-Rhine-Yssel cattle was 4.5%, ranging from 0% to 29.6% among half-sib groups. The average pedigree based relationship between the sire and the maternal grandsire was 0.05 and ranged from 0 to 1.04. Using a sire-maternal grandsire model the heritability was estimated at 0.22 (SEM=0.07) which is comparable with estimates for other dual purpose breeds. The coefficient of relationship between the sire and the maternal grandsire had an effect on retained placenta. The coefficient of relationship between the sire and the maternal grandsire was used as a proxy for the coefficient of relationship between dam and calf, which is correlated with the probability of major histocompatibility complex (MHC) class I compatibility between dam and calf. MHC class I compatibility is an important risk factor for retained placenta. Although the MHC class I haplotype is genetically determined, MHC class I compatibility is not heritable. This study shows that selection against retained placenta is possible and indicates that preventing the mating of related parents may play a role in the prevention of retained placenta.

Clinical endometritis in an Argentinean herd of dairy cows: risk factors and reproductive efficiency

The objectives of this study were to assess the clinical and metabolic risk factors for clinical endometritis, the likelihood for having a normal vaginal discharge during postpartum, and the effects of endometritis on milk yield, reproductive efficiency, and metabolic status in Holstein cows. The study was conducted in a commercial dairy herd (Cordoba, Argentina) where 303 Holstein cows were enrolled. Cows were body condition scored (1 to 5) and tail bled on -14, 7, 21, 31, 41, and 50 d relative to parturition. Cows having a vaginal discharge with presence of pus between 21 and 41 d postpartum (dpp) were diagnosed as having clinical endometritis. Plasma blood samples were analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and blood urea nitrogen using commercial kits and insulin-like growth factor 1, insulin, and leptin by RIA. Data were analyzed with PROC MIXED, PROC GENMOD, and PROC PHREG of SAS (SAS Institute Inc., Cary, NC). Abnormal calving and puerperal metritis increased the risk for endometritis [adjusted odds ratio (AOR)=2.21 for both]. High prepartum NEFA and high postpartum BHBA increased the risk for endometritis (AOR=1.003 and 1.001, respectively), whereas high prepartum blood urea nitrogen reduced it (AOR=0.853). Cut-offs of 456.6 μM NEFA and 402.5 μM BHBA had sensitivities of 0.69 and 0.58, and specificities of 0.88 and 0.86, respectively. The likelihood for having normal vaginal discharge increased with time (∼1% × dpp) and with normal calving. Cows with endometritis had higher milk yield than normal herdmates (27.8±0.9 vs. 25.7±0.4 kg/d), lower risk for pregnancy by 100 dpp (AOR=0.10), higher nonpregnancy risk by 200 dpp (AOR=2.87), and higher risk for culling than normal cows (AOR=2.28). Cows with endometritis had a lower hazard rate (0.44) for pregnancy and had approximately 70 d longer calving-to-conception intervals. Finally, endometritis had no effect on metabolic hormones. In conclusion, the risk for clinical endometritis increases with abnormal calving and puerperal metritis, as prepartum NEFA and postpartum BHBA concentrations increase. Prepartum NEFA and postpartum BHBA could be useful for the prediction of endometritis. Last, clinical endometritis has detrimental effects on reproductive efficiency, as affected cows take longer to get pregnant and are at higher risk for culling.

Short communication: Large-scale study on effects of metritis on reproduction in Danish Holstein cows

A total of 398,237 lactations of Danish Holstein dairy cows were studied with the main objective to investigate the effects of metritis on 2 fertility variables: interval from calving to first insemination (CFI) and nonreturn rate at 56 d after first insemination (NR56), adjusting for milk production and body condition score as confounders. Metritis was defined as a score of at least 5 (indicating purulent vaginal discharge with abnormal smell) on the Danish uterine score scale (from 0 to 9, used to evaluate vaginal discharge in the first 19 d postpartum on all fresh cows in herds participating in a national herd health program). Cows with metritis in early lactation presented a significant delay in first insemination (hazard ratio of 0.80) and a significantly reduced probability of success at first insemination. The effect of metritis was also present after adjusting for possible effects of body condition score, milk production in the first month of lactation, parity, herd, and year-season. Only a small part of the observed effect of metritis could be explained by variation in body condition score at calving and milk production in the first month after calving. The results from this large-scale study underscore the deleterious effects of metritis on the fertility variables CFI and NR56.

Use of ultrasound in the reproductive management of dairy cattle

The significant decrease in fertility observed in dairy cattle during the last few decades and increasing requirements by the farmers have made a regular control of reproduction indispensable to urgently identify and solve potential problems affecting reproductive efficiency. Traditionally, the main diagnostic methods used for reproductive control in cattle included rectal palpation, inspection of vaginal discharge and vaginoscopy. Since the 1990 s, the use of ultrasound (US) has become a common diagnostic method as a result of the new advances made in the development of US scans: smaller size, high level of autonomy, high image quality and accessible prices. Ultrasound improves accuracy in the diagnoses of stages of the oestrous cycle, ovarian and uterine pathologies, and pregnancy diagnosis. In addition, it facilitates the diagnosis of alterations during pregnancy (embryo mortality, foetal malformations, etc.) and helps determining foetal sex from day 55 of pregnancy.

Comparison of ultrasonography and histopathology for the diagnosis of endometritis in Holstein-Friesian cows

Reproductive diseases are a great barrier to dairy production, as they diminish fertility and cause economic loss. In this context, endometritis plays an important role. Different diagnostic techniques exist for endometritis that vary in sensitivity and specificity. This work aimed to evaluate and compare ultrasonographic and histopathological examinations, and combinations thereof, for the diagnosis of endometritis by determining their sensitivity, specificity, and kappa agreement coefficients using endometrial cytology as the gold standard. We developed an adaptive reading score to perform histological examination of the uterus. In this study, 76 Holstein-Friesian cows, 21 to 47 d postpartum, without vaginal catarrh were submitted to gynecological examinations, including ultrasonographic examination, an endometrial cytology examination, and a uterine biopsy. Our results indicate that ultrasonography is a practical and effective diagnostic method, and a combination of the determination of intrauterine fluid and cervical diameter was the most efficient ultrasonographic method, with 50% sensitivity and 88% specificity. Histopathological examination was a useful diagnostic method that provided rich detail on endometrial inflammation, and allowed evaluation of different components of the tissue such as the epithelium, lamina propria, endometrial glands, and blood vessels; this method had 44% sensitivity and 92% specificity for diagnosis of endometritis.

TRPV6 and Calbindin-D9k-expression and localization in the bovine uterus and placenta during pregnancy

BACKGROUND

Transient receptor potential channel type 6 (TRPV6) and Calbindin-D9k (CaBP-9k) are involved in the active calcium (Ca2+) transport mechanism in many tissues including placenta and uterus, suggesting a role in the establishment and maintenance of pregnancy. Moreover, TRPV6 and CaBP-9k seem to support the materno-fetal Ca2+ transport that is crucial for fetal Ca2+ homeostasis, bone growth and development. However, it is unknown if these proteins are also involved in the aetiology of pathologies associated with parturition in cows, such as retained fetal membranes (RFM). The aim of the current study was to create an expression profile of uterine and placentomal TRPV6 and CaBP-9k mRNAs and proteins during pregnancy and postpartum in cows with and without fetal membrane release.

METHODS

Uteri and placentomes of 27 cows in different stages of pregnancy and placentomes of cows with and without RFM were collected. Protein and mRNA expression of TRPV6 and CaBP-9k was investigated by real-time PCR, immunohistochemistry and Western blot.

RESULTS

In the uterine endometrium, highest TRPV6 and CaBP-9k expression was found in the last trimester of pregnancy, with a particular increase of protein in the glandular epithelium. In the placentomes, a gradual increase in TRPV6 mRNA was detectable towards parturition, while protein expression did not change significantly. Placentomal CaBP-9k expression did not change significantly throughout pregnancy but immunohistochemistry revealed an increase in staining intensity in the maternal crypt epithelium. Immunohistochemical, stronger placental CaBP-9k signals were seen in animals with RFM compared to animals with an undisturbed fetal membrane release, while protein levels, measured by Western blot analyses did not change significantly.

CONCLUSIONS

The results of the present study demonstrate a dynamic expression of TRPV6 and CaBP-9k during pregnancy in the bovine uterine endometrium and placentomes, suggesting a functional role for these proteins in Ca2+ metabolism during pregnancy. The temporal and spatial expression patterns indicate that TRPV6 and CaBP-9k may be involved in materno-fetal Ca2+ transport, mainly through an interplacentomal transport, and that both proteins may participate in physiological processes that are crucial for fetal and placental development. However, neither TRPV6 nor CaBP-9k seem to be causative in the retention of fetal membranes.

Therapeutic efficiency of antibiotics and prostaglandin F2α in postpartum dairy cows with clinical endometritis: an evidence-based evaluation

The occurrence of vaginal discharge in postpartum dairy cows is generally diagnosed as clinical endometritis. This uterine condition is associated with reduced fertility and economic loss for the dairy industry. Therapeutic approaches include the systemic or intrauterine application of antibiotics or the injection of prostaglandin F2α and analogues to cause luteolysis and uterine contractions to evacuate the infected content. The treatment of clinical endometritis remains a subject of considerable controversy in the literature. Better understanding of the reproductive biology of normal versus abnormal uterine involution and immune mechanisms will allow more efficient diagnostic methods and a more efficient therapeutic approach.

Effect of mastitis during the first lactation on production and reproduction performance of Holstein cows

The aim of this study was to evaluate the effect of postpartum mastitis between first calving and subsequent conception on production and reproduction performance as well as culling of Holstein cows. A data set of 9,183 first lactation cows was used. Results showed that the first cumulative 100 days' milk production and the milk yield standardized to 305 days were affected by the interval from calving to first mastitis (P < 0.05). Cows with one episode of mastitis produced more milk than those with repeated episodes of mastitis (P < 0.01). Increase in the number of mastitis episodes and also decrease in interval between first calving and mastitis increased services per conception (P < 0.001). Mastitis episode and the interval between calving and first mastitis had no apparent impact on the calving to conception interval (P > 0.05). Calving year, calving difficulty score, and cumulative first 60 days milk production had significant impacts on mastitis risk (P < 0.05). The interval from calving to the first incidence of mastitis decreased over the period studied (P < 0.001). Productive life tended to be decreased due to mastitis (P = 0.07). Survival analysis showed a significant difference between the lengths of productive life for cows with different intervals from calving to first mastitis (P < 0.01). The results demonstrated that clinical mastitis between first calving and conception reduced production and reproduction performance with an increase in chance of culling.

Experimentally induced mastitis and metritis modulate soy bean derived isoflavone biotransformation in diary cows

The present study compared the changes in isoflavone (daidzein and genistein) and their metabolite (equol and para-ethyl-phenol) concentrations in the blood plasma of cows with induced mastitis and metritis after feeding with soy bean. Sixteen cows were divided into four groups: control for mastitis group, cows with induced mastitis group, control for metritis group, and cows with induced metritis group. All cows were fed a single dose of 2.5 kg of soy bean and then blood samples were taken from the jugular vein for 8 h at predetermined intervals. The concentrations of soy bean-derived isoflavones and their active metabolites were measured in the blood plasma on HPLC system. β-Glucuronidase activity in the blood plasma of cows was measured by fluorometric method. In the blood plasma of cows with induced mastitis and metritis, we found considerably higher concentrations and time-dependent increase in isoflavone metabolites (equol and para-ethyl-phenol) with reference to cyclic cows (P < 0.05). Moreover, we noticed significant decrease of genistein in the blood plasma of the cows with induced metritis compared with control cows (P < 0.05). In addition, in the blood plasma of the cows with induced metritis, we found an increase in β-glucuronidase activity compared with control cows (P < 0.05). In conclusion, health status of the females influenced the concentrations of isoflavone metabolites in the blood plasma of the cows. Experimentally induced mastitis and metritis increased isoflavone absorption, biotransformation and metabolism. Therefore, we suggest that cows with induced mastitis and metritis are more exposed to active isoflavone metabolite actions than healthy cows.

Short communication: genetic effects of heat stress on days open for Thai Holstein crossbreds

Seasonality of days open (DO) for Thai crossbred Holsteins was examined and genetic effects of heat stress on DO open were determined. Data included 18,413 records for first and second parities of 12,162 cows that calved between 1990 and 2006. Least squares means for DO were estimated using a model with fixed effects of herd-year of calving, breed group based on percentage of Holstein genetics, calving month, calving age, and parity. A reaction norm model and solutions for calving month were used to calculate a heat stress index. Variance components were estimated with a multitrait random regression model. Days open were greatest for cows calving in March (summer) and fewest in October (late rainy season) for all breed groups and parities. Estimates of additive genetic and residual variances and heritability varied by calving month. Residual variances increased and additive genetic variance decreased with percentage of Holstein genetics and parity. Heritability estimates for DO ranged from 7.1 to 8.4% for first-parity cows with <87.5% Holstein genetics, 5.9 to 8.0% for 87.5 to 93.6% Holstein genetics, and 5.8 to 7.8% for ≥93.7% Holstein genetics and from 6.3 to 7.9, 4.9 to 7.3, and 4.5 to 7.7% for the corresponding breed groups for second parity. Genetic correlations between additive genetic effects on DO with and without heat stress considered were 0.43 for first-parity cows with <87.5% Holstein genetics, 0.46 for those with 87.5 to 93.6% Holstein genetics, and 0.52 for those with ≥93.7% Holstein genetics; correlations were 0.46, 0.51, and 0.55 for the corresponding breed groups for second parity. Effect of heat stress on DO was greater for second than first parity and was particularly large for cows with ≥93.7% Holstein genetics. Fewer DO can be achieved in Thailand through selective breeding of cows with <87.5% Holstein genetics.

Differential smoothing of time-series measurements to identify disturbances in performance and quantify animal response characteristics: An example using milk yield profiles in dairy cows

Recent advances in on-farm technology now provide us with multiple time-series of reliably measured indicators of animal performance and status at the level of the individual. This paper presents a smoothing approach for extracting biologically meaningful features from such time series using bovine milk yield data as an example. The main goal of this study was to illustrate how the method can be used to detect production deviations, extract quantifiable features of the deviation profiles, and thus provide means to examine hypotheses concerning the nature of the deviations. The effectiveness of the method was assessed with complete lactation curves from 47 Holstein cows. Within their lactations, the cows were each subjected to 1 nutritional challenge for a period of 4 d (their standard diet: a maize silage-based total mixed ration was diluted with 60% wheat straw), which provoked a decline in the milk yield in all cows. The challenge was imposed between the same calendar days for all cows. Thus, the cows were at different stages of lactation: early (n = 14), mid (n = 15), and late (n = 18). Each milk-yield curve was decomposed into components that capture the short-term deviations of the cow such as the response to the nutritional challenge and describe the phenotypic potential yield function of that cow throughout its lactation. The difference between the 2 components gives a measure of the milk loss. In all, 480 deviations were detected from the complete lactations of 47 cows. The milk loss provoked by the feeding challenge (n = 47) was significantly related to the milk yield immediately before the challenge (r = 0.86, P < 0.01). The correlation between the rate of recovery and milk loss was (r = 0.94, P < 0.01). Further, there was no significant slope (P > 0.1) to the relationship between the ratio (rate of recovery/milk loss) and days from calving, indicating that the force of recovery was unaffected by stage of lactation. These results suggest that differential smoothing can be a useful tool for quantifying biological disturbances in animal performance and for extracting features that relate to the potential and robustness of an animal.

Influence of energy balance on the somatotrophic axis and matrix metalloproteinase expression in the endometrium of the postpartum dairy cow

Postpartum dairy cows enter a period of negative energy balance (NEB) associated with low circulating IGF1, during which the uterus must undergo extensive repair following calving. This study investigated the effects of NEB on expression of IGF family members and related genes in the involuting uterus. Cows were allocated to two treatments using differential feeding and milking regimes to produce mild NEB or severe NEB (SNEB). Uterine endometrial samples collected 2 weeks post partum were analysed by quantitative PCR. The expression of IGF-binding protein 4 (IGFBP4) mRNA increased in the endometrium of SNEB cows, with trends towards increased IGFBP1 and reduced IGFBP6 expression. There were no significant differences between treatments in mRNA expression of IGF1, IGF2 or of any hormone receptor studied, but significant correlations across all cows in the expression levels of groups of receptors suggested common regulatory mechanisms: type 1 IGF receptor (IGF1R), IGF2R and insulin receptor (INSR); GHR with ESR1; and ESR2 with NR3C1. The expression of IGF1R and INSR also positively correlated with the circulating urea concentration. Matrix metalloproteinases (MMPs) are important in tissue remodelling and can affect IGF signalling via interaction with IGFBPs. The expression levels of MMP1, MMP3, MMP9 and MMP13 mRNAs all showed major upregulation in the endometrium of cows in SNEB and all except MMP9 were highly correlated with expression of IGFBP4. Alpha(2)-HS-glycoprotein (AHSG) and PDK4, two genes implicated in insulin resistance, were also highly expressed in SNEB. These results suggest that cows in SNEB experience alterations to the IGF and insulin signalling pathways in the postpartum endometrium. This may affect the rate of tissue repair with a possible negative impact on subsequent fertility.

A review of the causes of poor fertility in high milk producing dairy cows

Fertility in dairy cows has declined over the past five decades as milk production per cow has increased. Many hypotheses have been proposed to explain this including issues of genetics, physiology, nutrition and management, and these factors have been investigated at the animal, organ and cellular level at critical time points of the productive life of dairy cows. This paper reviews the physiological events and their causes and consequences affecting fertility in dairy cows and summarises these in a downloadable poster. We consider the following points to have the greatest negative impact on fertility and that they need to be prioritised in efforts to ameliorate the problem (others have been included in the review). Firstly, minimise negative energy balance and resolve any infection of the post partum uterus. Secondly, expression and detection of oestrus followed by insemination with high quality semen (day 0). Thirdly, ovulation and fertilisation of a high quality oocyte (day 1). Fourthly, an early increase in progesterone secretion from the corpus luteum (days 3–7). Fifthly, the uterine endometrium must produce an early and appropriate environment to stimulate embryo development (days 6–13). This leads to sixthly, a large embryo producing adequate quantities of interferon tau (days 14–18) that alters uterine prostaglandin secretion and signals maternal recognition of pregnancy (days 16–18). Future strategies to improve dairy cow fertility are needed for the benefit of the dairy industry and for cow welfare and should be based upon an integrative approach of these events.

Effect of Johne's disease status on reproduction and culling in dairy cattle

Among the costs attributed to Mycobacterium avium ssp. paratuberculosis (MAP) infection in dairy cattle, the effects on reproduction and culling are the least documented. To estimate the cost of MAP infections and Johne's disease in a dairy herd, the rates of calving and culling were calculated for cows in each stage of MAP infection relative to uninfected cows. Data from 6 commercial dairy herds, consisting of 2,818 cows with 2,754 calvings and 1,483 cullings, were used for analysis. Every cow in each study herd was tested regularly for MAP, and herds were followed for between 4 and 7 yr. An ordinal categorical variable for Johne's disease status [test-negative, low-positive (low-shedding or ELISA-positive only), or high-shedding] was defined as a time-dependent variable for all cows with at least 1 positive test result or 2 negative test results. A Cox regression model, stratified on herd and controlling for the time-dependent infection variable, was used to analyze time to culling. Nonshedding animals were significantly less likely to be culled in comparison with animals in the low-shedding or ELISA-positive category, and high-shedding animals had nonsignificantly higher culling rates than low-shedding or ELISA-positive animals. Time to calving was analyzed using a proportional rates model, an analog to the Andersen-Gill regression model suitable for recurrent event data, stratifying on herd and weighted to adjust for the dependent censoring caused by the culling effects described above. High-shedding animals had lower calving rates in comparison with low-shedding or ELISA-positive animals, which tended to have higher calving rates than test-negative animals.

Prevalence of clinical endometritis and its impact on reproductive performance in grazing dairy cattle in Argentina

The objective of this study was to evaluate the prevalence of clinical endometritis and its impact on reproductive performance in grazing dairy cattle in Argentina to compare data with previous reports from herds kept in confinement housing systems. A total of 243 Holstein dairy cows from three commercial dairy farms in Buenos Aires Province (Argentina) were examined for the signs of clinical endometritis 18-38 days postpartum (dpp) by external inspection and manual vaginal examination. Vaginal discharge was scored into the categories VDS 0 (transparent, clear mucus), VDS 1 (mucupurulent discharge), VDS 2 (purulent discharge) and VDS 3 (purulent discharge with fetid odour). Cows diagnosed with VDS 1 to VDS 3 were regarded as affected with clinical endometritis and cows with VDS 0 as free of clinical endometritis. All cows were re-examined 14 days later following the same examination protocol. Prevalence of clinical endometritis 18-38 dpp was 35% and decreased to 18% at re-examination. Cows with no palpable ovarian structures or periparturient disorders were at higher risk for clinical endometritis. Hazard for pregnancy was significantly lower in cows with purulent or fetid odour discharge compared with reference cows with no discharge (HR=0.49; p=0.01), resulting in a lower proportion of cows pregnant by 360 dpp (66% vs 78%). Furthermore, the number of services per pregnancy was higher for cows with clinical endometritis than for cows without clinical endometritis (4.4 vs 3.1; p=0.04). Cows with clinical endometritis were 1.6 times as likely to be culled as cows with no signs of clinical endometritis. In conclusion, the prevalence and the impact of clinical endometritis in a pasture-based, extensive dairy production system in Argentina were similar to previously published data from dairy farms with confinement production systems.

Selected pro-inflammatory factor transcripts in bovine endometrial epithelial cells are regulated during the oestrous cycle and elevated in case of subclinical or clinical endometritis

Endometrial cells take part in embryo-maternal communication, as well as supporting the immune system in defending against invading pathogens. The aim of the present study was to examine the mRNA expression of factors that have been suggested to be involved in both events in the bovine endometrial epithelium, namely bovine granulocyte chemotactic protein 2 (CXCL5), interleukin-1 beta (IL1B), IL6, IL8, tumour necrosis factor (TNF), cyclooxygenase 2 (PTGS2) and haptoglobin (HP). Samples were collected in vivo from cows on Days 21-27 postpartum by the cytobrush method to evaluate the correlation between inflammatory factors and uterine health (cows with signs of clinical or subclinical endometritis and healthy cows). Bovine uteri were collected at the abattoir to investigate oestrous cycle-dependent mRNA expression patterns. Real-time reverse transcription-polymerase chain reaction revealed that the expression of CXCL5, IL1B, IL8 and TNF mRNA was significantly higher in cows with subclinical or clinical endometritis compared with healthy cows. The expression of CXCL5, IL1B and IL8 mRNA was increased around ovulation compared with the luteal phase. There was no indication of either oestrous cycle-dependent expression or a correlation with uterine health for IL6, PTGS2 and HP transcripts. These results suggest that CXCL5, IL1B, IL8 and TNF may represent potential marker genes for the detection of cows with subclinical endometritis and for monitoring new therapeutic approaches.

Reactive oxygen species (ROS): involvement in bovine follicular cysts etiopathogenesis

Ovulation is compared to an acute inflammatory process during which vasoactive agents, prostanoids, leukotrienes and Reactive Oxygen Species (ROS) develop. The aim of this study was to evaluate the levels of ROS in cystic and follicular fluid, in order to establish their involvement in the etiopathogenesis of Cystic Ovarian Follicle (COF) in dairy cows. The study was conducted in 30 healthy cows (group C) and 30 cows affected by COF (group COF). The fluid of follicular cysts and of preovulatory follicles was drawn by means of ultrasound guided aspiration from the cows of both groups. The fluid obtained was analyzed by a photometric analytical system to detect ROS level. ROS concentration was statistically lower in the cystic fluid than in the follicular one (62.4 +/- 13.36 U.Carr vs. 84.89 +/- 26.99 U.Carr) (p<0.05), thus suggesting that an alteration of the cascade responsible for ROS production may be implicated in the complex etipathogenesis of COF.

Risk factors for calving assistance and dystocia in pasture-based Holstein-Friesian heifers and cows in Ireland

The incidence of and risk factors associated with calving assistance and dystocia in pasture-based dairy herds were determined from analysis of 152,641 records of full-term calvings from Holstein-Friesian dams served by artificial insemination (AI) sires of seven breeds in herds of 20 calvings or more per year over 4 years. The overall incidence of calving assistance and dystocia was 31.1% and 6.8%, respectively. The incidence in primiparae and pluriparae was 40.0% and 28.2% for assistance, and 9.3% and 5.8% for dystocia, respectively. Association analyses were undertaken using generalised estimating equations using a logit link function. The likelihood of calving assistance or dystocia did not change over time but was greatest in autumn and in spring. The likelihood of calving assistance or dystocia was greater for males in primiparae and males sired by Charolais sires. The odds of calving assistance and dystocia were greater in twin calves (OR 2.0 and 2.4; P<0.001) and in dams that had dystocia at the previous calving (OR 1.65 and 2.9; P<0.001). The logit of the probability of calving assistance and dystocia increased linearly per unit increase in sire predicted transmitting ability for direct calving difficulty. The probability of assisted calving, but not dystocia, increased linearly in primiparae as animals calved at a younger age relative to the median age at first calving. Herd size and day of the week of calving were not associated with the odds of dystocia. Stakeholders must focus on identified modifiable risk factors to control the incidence of dystocia in dairy herds.

How to evaluate and quantify the influence of coincidence on fertility and herd health parameters? A practical overview of frequently used and abused statistical techniques in research and practice

In this article, frequently encountered statistical questions and methods used both in research and in daily practice are described and explained. First, the concepts of variability and uncertainty are explained and illustrated. From this, it is explained how variation can be quantified and how the limits of what can be expected as a result of normal variation are determined both for continuous and binary data. Based on the basic concepts of probability theory, an introduction to risk assessment was given. Finally it is explained how to test whether individual observations lie outside the normal range or the test whether populations are different from each other. All these are carried out avoiding theory and formulas as much as possible and illustrated with real examples from reproduction and herd health.