Árpád Csaba Bajcsy

Comparison of a commercial bovine pregnancy-associated glycoprotein ELISA test and a pregnancy-associated glycoprotein radiomimmunoassay test for early pregnancy diagnosis in dairy cattle.

The present study aimed to compare the accuracy of a commercial PAG-ELISA test (Bovine Preg Test 29) and bovine pregnancy-associated glycoprotein radioimmunoassay (PAG-RIA) for diagnosing pregnancy at Day 28 after insemination in dairy cows. Transrectal ultrasonography (TRUS) was performed in 100 Holstein-Friesian cows at Day 28 after artificial insemination (AI; Day 0) to diagnose pregnancy. After TRUS examination, blood sample was collected from the coccygeal vessels of each cow to measure the concentrations of bPAGs by PAG-RIA test and Bovine Preg Test 29. Milk samples were collected at Days 0, 21 and 28 for measurement of progesterone (P4) by ELISA test. The cows were re-examined by TRUS at Day 42 to confirm the pregnancy diagnoses. The actual gold standard was based on TRUS outcomes at Day 28 that agreed with the outcomes of PAG-RIA test or PAG-ELISA test. If the outcomes of TRUS at Day 28 and PAG-RIA test and PAG-ELISA test did not agree, the gold standard was based on the outcome of TRUS at Day 42. Out of 100 inseminated cows, 41 were confirmed pregnant at Day 28 after AI. Based on the actual gold standard, the sensitivity of TRUS, PAG-ELISA and PAG-RIA tests for diagnosing pregnant cows at Day 28 were 92.7%, 90.2% and 100%, while the specificity of the three tests for diagnosing non-pregnant cows were 91.5%, 98.3% and 94.4%, respectively. The overall accuracy of the three tests were 92%, 95% and 97%, respectively. The degree of agreement (Kappa±S.E.) between PAG-RIA and PAG-ELISA test was 0.90 ±0.04. The degrees of agreement between PAG-RIA and PAG-ELISA and TRUS at Day 28 were 0.80±0.05 and 0.76±0.06, respectively. In conclusion, the commercial PAG-ELISA test is a highly accurate method for diagnosing early pregnancy in dairy cows on Day 28 after AI and may be used as an alternative method to the TRUS and the PAG-RIA test.

Properties and antimicrobial susceptibility of Trueperella pyogenes isolated from bovine mastitis in China

Trueperella (T.) pyogenes is an opportunistic pathogen that causes suppurative diseases in domestic animals. In this work, the properties, pathogenesis and phenotypic diversity of T. pyogenes isolates from bovine mastitis were studied. Both pyolysin (plo) and collagen-binding protein (cbp) virulence factor genes were detected by PCR in all T. pyogenes isolates (n = 50). Using the tissue culture plate method, 90% of T. pyogenes isolates were able to form biofilms. The minimum inhibitory concentrations (MICs) of 13 antimicrobials against T. pyogenes isolates were determined. High susceptibility was observed to rifampin (96%), ampicillin (94%), ciprofloxacin (94%), and penicillin (92%), while low susceptibility was found to trimethoprim-sulphamethoxazole (10%) and bacitracin (2%). The intracellular assay revealed that T. pyogenes isolates had different cytopathogenic effects on cells. The high percentage (28.6%) of T. pyogenes isolates suggests that this bacterium is an important contributor to mastitis. Moreover, the high occurrence of multidrug resistance, biofilm production, intracellular survival, and the temporal dynamics of T. pyogenes interactions are key factors for a better understanding of how immunity acts on infections with these bacteria and how they evade immune surveillance, thus highlighting the need for the prudent use of antimicrobial agents in veterinary medicine.

Relationship of progesterone, bovine pregnancy-associated glycoprotein-1 and nitric oxide with late embryonic and early fetal mortalities in dairy cows

The aim of the present study was to determine the relationship of progesterone (P4), bovine pregnancy-associated glycoprotein-1 (bPAG-1) and nitric oxide (NO) levels with late embryonic (LEM; day 28 to day 42) and early fetal mortalities (EFM; > day 42 to day 56) in dairy cows. Transrectal ultrasonography (6–8 MHz) was performed in 100 Holstein-Friesian cows at days 28, 42 and 56 after artificial insemination (AI; day 0) to diagnose pregnancy and to monitor the fate of the embryo. After ultrasound scanning of each cow, a milk sample was collected for assessment of P4 by an ELISA test and a blood sample was collected for assessment of bPAG-1, by using a double-antibody radioimmunoassay, and serum NO metabolites (nitrate + nitrite). Based on ultrasonographic examinations and bPAG-1-RIA, 41 of 100 inseminated cows were confirmed pregnant at day 28 after AI. Nine cows suffered of LEM, and 6 cows suffered of EFM and the overall pregnancy loss rate was 36.6% (15/41) between days 28 and 56 of pregnancy. By logistic regression analysis, there were no significant relationships between the level of P4 and bPAG-1 at day 28 after AI and the occurrence of LEM and EFM. Also, there were no significant relationships between the levels of P4 and bPAG-1 at day 42 and the occurrence of EFM. On the other hand, a significant relationship (P<0.05) was found between NO level at day 28 and the occurrence of LEM. In conclusion, measurement of the serum NO concentration at day 28 of pregnancy might help to predict the outcome of pregnancy by day 42 in dairy cows but further studies are needed to confirm this.

Electronic monitoring of rumination activity as an indicator of health status and production traits in high-yielding dairy cows.

In view of the demonstrated relationship between rumination time and health status, the general welfare and metabolic condition of ruminants are often assessed by the examination of rumen function. The main goal of this study was to monitor the daily rumination activity (RA) and its connection with actual liveweight (LW), milk yield (MY) and with two diseases (subclinical hyperketonaemia - SHK, uterine disease - UD) in 96 cows on the basis of a total of 1638 observations in Israel. The studied sample gave a highly significant response, showing that the selected diseases had a diminishing impact on RA and LW and no influence on MY. It can be concluded that the change of RA as determined by electronic monitoring, complemented by the change of LW, is a useful general indicator of health status and subclinical disease before the appearance of clinical signs.

EVALUATION OF THE ON-LINE ELECTRICAL CONDUCTIVITY OF MILK IN MASTITIC DAIRY COWS

Mastitis is a persistent, inflammatory reaction of the udder tissue, which entails a decline in potassium, and is also responsible for a higher somatic cell count (SCC) and electrical conductivity (EC) of milk. The measurement of EC is an indirect, rapid method to detect subclinical mastitis from milk. The aim of this study was to analyse the EC of milk throughout the lactation, around the day of mastitis detection, and also to estimate its heritability based on data from a large-scale dairy farm. Shortly after calving the EC value generally decreases; however, it was discovered that from the thirteenth week onwards, substantial differences arise between the mastitic and healthy groups of cows. The authors observed a significant (P < 0.001) increase in EC before the detection of clinical mastitis. This higher value (around 11 mS) persisted for 4 days, then it gradually returned to the normal level. The EC of milk from daughters sired by different bulls responded differently in case of mastitis. The heritability of EC seems to be high (h2 = 0.56). Therefore, the EC trait can be a beneficial indicator in detecting mastitis and should be considered in sire selection.

Control of ovulation after prostaglandin treatment by means of ultrasonography and effect of the time of ovulation on conception rate in dairy cows

Primiparous and multiparous lactating crossbred dairy cows (after Day 40 postpartum) with a mature corpus luteum (CL) (diameter of ≥ 17 mm determined by ultrasonography) and having a follicle with a diameter of ≥ 10 mm were treated with natural prostaglandin F2α (n = 80). Those from the cows that showed oestrus within 5 days after treatment were inseminated (Group 1: n = 39). Other group of cows showing oestrus without treatment (Group 2: n = 41) were inseminated and served as controls. The ovaries of each cow were scanned by transrectal ultrasonography from the day of detected oestrus (Day -1p.m.) until ovulation, to measure the changes in the areas of the CL and the largest follicle and to determine the occurrence of ovulation. Although no significant differences were found between the treated and untreated cows in terms of a reduction in the area of the corpora lutea and of an increase in the area of the dominant follicles, the mean area of these follicles in Group 2 was somewhat greater than in Group 1. The highest conception rate was achieved if AI was performed at the same day as ovulation occurred in both groups (conception rate in treated group was: 62.5%, in untreated group: 66.6%, respectively) between Day 0a.m. to Day 0p.m.. In Group 1, 54.5% conception rate has been achieved if ovulation occurred between Day 0p.m. to Day 1p.m., or 50% between Day 1p.m. to Day 2p.m. after AI, and 53.3% and 44.4% in Group 2, respectively. The conception rate for cows that ovulated before AI in Group 2 was 25%. No ovulation occurred in 7 cows until Day 2p.m. after AI and none of them became pregnant. The overall conception rate was approximately 50% in both groups, but when the cows had ovulated too early or too late relative to the time of AI, the conception rate was significantly lower, thus determination of the optimal time for AI is of great practical importance in dairy herds.