Vaginal Microbiota Composition and Its Relationship with Fertility in Repeat Breeder Dairy Cows

In this study, blood serum was collected from 162 repeat breeder (RB) dairy cows and tested by enzyme linked immunosorbent assay (ELISA). Of these samples, 87 were bovine herpesvirus type-4 (BHV-4) seropositive and 75 were BHV-4 seronegative. The prevalence of BHV-4 was determined as 53.70% amongst RB dairy cows. In the current study the seroprevalence was high. The average days open (DO) of pregnant BHV-4 seropositive RB cows was significantly longer (p<0.01) than that of pregnant BHV-4 seronegative RB cows, but was not significant for age of animals (p=0.186) or conception rate (CR) (p=0.14). The averages calving to the fourth insemination date (CFIDI) and age of nonpregnant BHV-4 seropositive RB cows was significantly higher (p< 0.05) than non-pregnant BHV-4 seronegative RB cows. In conclusion, a close fertility negative relationship existed between BHV-4 infections and fertility in RB dairy cows.

To determine herd characteristics and management practices associated with milk production in dairy herds enrolled in official Dairy Herd Improvement Association (DHIA) programs in Ohio. 186 dairy farms in Ohio. All herds in official DHIA programs in 9 counties were invited to participate. Information regarding herd characteristics and management practices was obtained, using a standardized questionnaire. Bulk-tank milk samples were obtained for bacteriologic culture. Official DHIA test-day records were obtained, and associations were identified, using multivariable ANOVA procedures. Of 479 eligible producers, 186 (39%) participated, and consecutive bulk-tank milk samples were available for culture from 172 (36%). Streptococcus agalactiae and Mycoplasma spp were not recovered from bulk-tank milk samples, but Staphylococcus aureus was recovered from 64 (37%) herds. Mean (+/- SD) number of lactating cows in participating herds was 97+/-66, with 123 (66%) herds milking < 100 cows. The RHA was significantly associated with number of cows in milk, estimated percentage of herd detected in estrus, reported annual percentage of heifer calves born alive that died before 8 weeks old, percentage days in milk, use of bovine somatotropin during the preceding 2 years, and sex of the person completing the questionnaire. In this study, the strongest indicator of milk production was number of cows in milk. However, merely adding cows to a herd should not be considered to guarantee increased milk production, because other management traits could be confounded with increased number of cows in a herd.

Comparison of the effects of gonadotropin-releasing hormone, human chorionic gonadotropin or progesterone on pregnancy per artificial insemination in repeat-breeder dairy cows

This study aimed to (i) assess the prevalence of cytological endometritis (CYTO) diagnosed at artificial insemination (AI); (ii) evaluate the effect of CYTO on the pregnancy outcome of the same AI sample; and (iii) determine the risk factors associated with CYTO diagnosed at AI in repeat breeder (RB) dairy cows. We analysed the productive and reproductive performances of 146 RB Holstein-Friesian cows. To obtain a CYTO sample at AI, we used the cytotape technique. Generalized mixed effect models were computed to find the risk factors associated with the pregnancy and CYTO outcome. Based on ≥1% PMN cut-off point, the CYTO prevalence at AI in RB cows was 25.3%. The overall pregnancy at AI was 44.2%. The conception rate in CYTO-positive (n=37) RB cows was 29.7% versus 49.5% for CYTO-negative (n=109) cows. A RB cow diagnosed CYTO positive at AI had 0.47 [odds ratio (OR)] odds to become pregnant in comparison with a CYTO-negative cow. Cows that produced more milk than their counterparts in this study had increased odds (OR=1.01) to be CYTO positive at AI. A novel risk factor positively associated with CYTO diagnosed at AI in RB cows was the level of daily milk urea (OR=1.11). To conclude, CYTO at the moment of AI had a significantly negative effect on the pregnancy outcome in RB dairy cows. However, as only one of fourth of RB cows is affected with CYTO at AI, it may not be considered a key element associated with the RB syndrome.

Administering saline to 14 repeat breeders or 100 μg GnRH to 38 repeat breeders resulted in a greater (P=.07) proportion of pregnancies at 42 to 56 days after third service and fewer (P<.05) lost pregnancies during the 25- to 38-day period of placentation. Concentrations of LH in serum of six repeat breeders previously given 100 μg GnRH 12 hr after detected estrus (day 0) were reduced (P<.05) on days 1, 3, and 8 after estrus compared to those in six cows previously given saline at estrus. Concentrations of FSH were similar among treatment groups on days 1 and 3, but were elevated (P<.05) on day 8 in GnRHtreated cows. Furthermore, all six GnRH-treated cows had detectable FSH pulses on day 8 compared to two of six control cows. Concentrations of progesterone in serum were elevated (P<.05) on days 8 to 10 after estrus in GnRH-treated cows, and their corpora lutea obtained on day 10 after estrus and treatment contained a greater (P<.05) proportion (31 vs. 14%) of large-diameter (21 to 37 μm) luteal cells and a lesser (P<.05) proportion (69 vs. 86%) of small-diameter (10 to 17 μm) luteal cells than corpora lutea from control cows. In vitro production of progesterone in response to LH was reduced (P<.05) in luteal tissue obtained on day 10 after estrus from cows previously treated with GnRH at estrus compared to cows given only saline. It appears that pregnancy rates are improved in repeat breeders given GnRH at the time of insemination as a result of increased secretion of progesterone related to alterations in the morphology and function of the corpus luteum, as well as possible influences of FSH secretion from the pituitary gland.; Dairy Day, 1991, Kansas State University, Manhattan, KS, 1991;

Dairy practitioners can solve problems of low milk production in dairy herds by following a systematic approach to diagnose the underlying herd problems. Important steps in this evaluation are determining the herd signalment, objectively characterizing herd milk production and carefully evaluating herd nutritional management. Cows within the herd can then be observed for body condition score, cud chewing activity, manure characteristics, locomotion and evaluated for sickness. Important additional diagnostic information can be gleaned from herd turnover records and measures of cow comfort. Herd based testing for ketosis (BHBA and NEFA), subacute ruminal acidosis and urea nitrogen may be indicated depending on findings up to this point in the investigation. Fresh cow health problems (usually triggered by fatty liver and ketosis) or lameness (usually caused by a combination of cow environmental problems in combination with subacute ruminal acidosis) are the two most common mechanisms for low herd production. Expect to find multiple causes for low herd milk production, and put the most confidence in diagnostic conclusions that are supported by more than one measure of herd performance.

Preovulatory follicle characteristics and oocyte competence in repeat breeder dairy cows

A slower than normal rise in progesterone concentrations and a lower total progesterone concentrations have been measured in low-fertility cows and repeat breeder (RB) heifers in the first six days after estrus. Several methods have been used to attempt to increase conception rates (CR) through a greater plasma progesterone (P4) concentrations during the luteal phase, including those that increase endogenous function of the existing corpus luteum (CL), induce accessory CL, or act as a direct progesterone supplement. The aim of the present study was to determine whether supplementing with exogenous P4 or the administration of gonadotrophin-releasing hormone (GnRH) or human chorionic gonadotrophin (hCG) during early luteal phase could increase CR in RB cows.

Mastitis is among the most prevalent disease that contributes for the reduction of milk production in dairy herds. Although several published studies have estimated the prevalence of mastitis, variation among studies is great. The objective of the present meta-analysis was to provide a pooled estimate of the prevalence of overall, clinical, and subclinical mastitis in dairy cattle in Ethiopia. A pooled estimate was also conducted by potential risk factors. The literature search was restricted to studies published in English language from January 2002 to June 2016. Meta-analysis of 39 studies was done under random effects model using metafor package in R software. The pooled estimate of the overall prevalence of mastitis on cow-basis was found to be 47.0% (95% confidence interval [CI] = 42.0, 52.0). The pooled prevalence with the 95% CI for clinical and subclinical mastitis was 8.3% (95% CI = 6.5, 10.3) and 37% (95% CI = 32.9, 40.7) respectively. There is a statistically significant and high heterogeneity of the prevalence estimates between published studies. The odds of occurrence of mastitis were higher in cows at early (odds ratio [OR] = 1.6; 95% CI = 1.4, 1.8) and late lactation (OR = 1.3; 95% CI = 1.2, 1.5) than mid lactation, in cows with 3-4 (OR = 1.5; 95% CI = 1.4, 1.7) and >4 parity number (OR = 2.9; 95% CI = 2.6, 3.4) than those with 1-2 parity number. Previous history of mastitis, floor type, milking hygiene, and udder injury had also statistically significant effect on pooled prevalence of mastitis (P < 0.05). The present study reported that there is high prevalence of mastitis in dairy cows in Ethiopia, which could contribute to the low productivity in lactating cows. The statistically significant association of risk factors such as floor type, milking hygiene, and presence of udder injury with mastitis may suggest that dairy farmers can reduce the occurrence of the disease by improving their management practices.

Distribution of seasonality of calving patterns and milk production in dairy herds across the United States

Bovine ephemeral fever (BEF) is a disabling viral disease of cattle and water buffaloes. It can cause significant economic impact through reduced milk production in dairy herds, loss of condition in beef cattle and loss of draught animals at the time of harvest. Available evidence indicates clinical signs of BEF, which include bi-phasic fever, anorexia, muscle stiffness, ocular and nasal discharge, ruminal stasis and recumbency, are due primarily to a vascular inflammatory response. In Australia, between 1936 and 1976, BEF occurred in sweeping epizootics that commenced in the tropical far north and spread over vast cattle grazing areas of the continent. In the late 1970s, following several epizootics in rapid succession, the disease became enzootic in most of northern and eastern Australia. In Africa, the Middle East and Asia, BEF occurs as also epizootics which originate in enzootic tropical areas and sweep north or south to sub-tropical and temperate zones. The causative virus is transmitted by haematophagous insects that appear to be borne on the wind, allowing rapid spread of the disease. Bovine ephemeral fever virus (BEFV) has been classified as the type species of the genus Ephemerovirus in the Rhabdoviridae. It has a complex genome organization which includes two glycoprotein genes that appear to have arisen by gene duplication. The virion surface glycoprotein (G protein) contains four major antigenic sites that are targets for neutralizing antibody. An analysis of a large number of BEFV isolates collected in Australia between 1956 and 1992 has indicated remarkable stability in most neutralization sites. However, epitope shifts have occurred in the major conformational site G3 and these have been traced to specific mutations in the amino acid sequence. BEFV isolates from mainland China and Taiwan are closely related to Australian isolates, but some variations have been detected. Natural BEFV infection induces a strong neutralizing antibody response and infection usually induces durable immunity. Several forms of live-attenuated, inactivated and recombinant vaccines have been reported but with variable efficacy and durability of protection. The BEFV G protein is a highly effective vaccine antigen, either as a purified subunit or expressed from recombinant viral vectors.

ObjectiveThe aim of our study was to determine the associations of heifer reproductive performance with survival up to the first calving, first-lactation milk yield, and the probability of being culled within 50 days after first calving.MethodsData from 33 large Holstein-Friesian commercial dairy herds were gathered from the official milk recording database in Hungary. The data of heifers first inseminated between January 1, 2011 and December 31, 2014 were analyzed retrospectively, using Cox proportional hazards models, competing risks models, multivariate linear and logistic mixed-effects models.ResultsHeifers (n = 35,128) with younger age at conception were more likely to remain in the herd until calving, and each additional month in age at conception increased culling risk by 5.1%. Season of birth was related to first-lactation milk yield (MY1; n = 19,931), with cows born in autumn having the highest milk production (p<0.001). The highest MY1 was achieved by heifers that first calved between 22.00 and 25.99 months of age. Heifers that calved in autumn had the highest MY1, whereas calving in summer was related to the lowest milk production (p<0.001). The risk of culling within 50 days in milk in first lactation (n = 21,225) increased along with first calving age, e.g. heifers that first calved after 30 months of age were 5.52-times more likely to be culled compared to heifers that calved before 22 months of age (p<0.001). Calving difficulty was related to higher culling risk in early lactation (p<0.001). Heifers that required caesarean section were 24.01-times more likely to leave the herd within 50 days after first calving compared to heifers that needed no assistance (p<0.001).ConclusionReproductive performance of replacement heifers is closely linked to longevity and milk production in dairy herds.

Concentrations of blood parameters and their interrelationships were investigated in dairy cows, during their lactation period, to determine the variations among parameters and the most reliable indices which could be useful for milk yield improvement. Blood was taken monthly during the 300 days of lactation and divided into early, mid, and late lactation. The highest monthly concentrations were observed on the fifth month of lactation for red blood cells (RBC), hemoglobin (Hb), calcium (Ca), potassium (K), sodium (Na), aminotransferase (AST), alkaline phosphatase (ALP), and packed cell volume (PCV) and the lowest were in the tenth month of lactation for blood urea nitrogen (BUN), cholesterol, hydroxybutyrate (BHB), Ca, K, Cl, and aminotransferase (AST). The maximum and minimum concentrations were found in early and late lactation, respectively. Mean comparison of parameter concentrations were significantly different among months and the three stages of lactation (with the exception of Hb and white blood cells). The most important correlations were between lymphocytes/neutrophils, Hb/PVC, RBC/PVC, Hb/RBC, AST/ALP, K/Na, triglycerides/Na, K/Ca, protein/Na, protein/Ca, triglycerides/cholesterol. Among these correlations, triglyceride, protein, and Na showed the strongest relationships and BHB, triglycerides, cholesterol, protein, BUN, Na, and ALP revealed the highest number of correlations with other parameters. In conclusion, blood parameter concentrations were different during the months and stages of lactation. The fifth month and mid-lactation for blood concentrations was a more reliable time than the other months and stages of lactation. Reliable relationships appeared between BUN, protein, triglyceride, Na, and BHB and could be applied as indices in supplementary studies related to the improvement of milk production in dairy herds.

Mastitis has long been recognized as a serious cause of ill-health and reduced milk production in dairy herds, but effective control measures compatible with day-to-day farming practice have been difficult to devise. This article reviews the progress in control that has been achieved and considers the prospects for the future.

Reproduction, especially impregnation, is a critical aspect of dairy cow management that directly influences herd milk productivity. We conducted a noninvasive hair mineral assay to compare the mineral profiles of two dairy cow groups: reproducible and repeat breeder, by investigating the levels of 11 essential minerals (Ca, Mg, Na, K, Fe, Cu, Mn, Zn, Cr, Se, and P) and 6 toxic elements (Hg, Pb, Cd, Al, As, and Ni) in both groups. We also conducted principal component and correlation matrix analyses to compare hair mineral patterns between the groups. Compared to their reproducible counterparts, repeat breeder cows had lower levels of Na, K, and Se. However, Fe, Cd, Al, and As levels were higher in repeat breeders than in their reproducible counterparts. The correlation matrix showed notable correlation patterns for each group. Ca, K, and Na levels were positively correlated in reproducible cows, whereas repeat breeder cows showed positive correlations only between Ca and K levels. Se showed positive correlations with Zn only in the reproducible cow group. Negative correlations were not found in the reproducible group, whereas the repeat breeder group exhibited 7 negative correlations. Despite the limitations of hair mineral analysis, this study provided useful insights into the reproductive potential of dairy cows. These findings aid in easing the prediction of repeat breeder occurrences in herds and are expected to facilitate timely mineral supplementation and other interventions to improve overall herd reproduction in dairy farms.