Witaya Suriyasathaporn

β-hydroxybutyrate levels in peripheral blood and ketone bodies supplemented in culture media affect the in vitro chemotaxis of bovine leukocytes

The role of ketone bodies on chemotactic capacities of leukocytes was characterized in two experiments. Experiment I was performed to investigate the association between serum beta-hydroxybutyrate concentrations (BHB) and in vitro chemotaxis of leukocytes. Cows were divided into low-BHB, medium-BHB, and high-BHB ones and classified according to their BHB. Leukocytes from high-BHB cows had a significantly lower chemotactic differential than leukocytes from low-BHB cows (p < 0.01). The effect of adding ketone bodies into in vitro chemotaxis cultures on leukocytes chemotaxis was studied in Experiment II. Either individual or a combination of commercial ketone bodies - sodium salts of BHB (BHBA), lithium salt of acetoacetate (ACAC), and acetone (Acetone) - were diluted in culture media and divided into eight concentrations corresponding to concentrations of bovine subclinical and clinical ketosis. For leukocytes from medium- and high-BHB cow, the chemotactic indexes of leukocytes were reduced by ACAC and Acetone. Chemotactic differentials of cultures with ACAC and acetone supplementation from both sources of leukocytes were significantly lower than that of the control culture (p < 0.05). For leukocytes from high-BHB cows, chemotactic indexes were suppressed in a ketone-body environment. In conclusion, leukocytes from naturally-occurring ketotic cows have lower chemotactic differentials than those from non-ketotic cows, and a chemotactic capacity indicated by a chemotactic differential is impaired when leukocytes migrate in an environment with ketone bodies in vitro.

A Cox proportional-hazards model with time-dependent covariates to evaluate the relationship between body-condition score and the risks of first insemination and pregnancy in a high-producing dairy herd

The objective of this study was to determine the relationship between body-condition score and postpartum reproductive efficiency in dairy cattle. Data on body-condition score, reproduction, diseases, and production from 1404 lactations of 639 cows, calving between January 1984 and November 1996 on a commercial farm, were used. The Cox proportional-hazards model with time-dependent covariates was used to qualify the relationship between body-condition score on a scale of 1 to 5 and risks of first insemination and pregnancy. Cows with body condition at calving < 3 had lower first-insemination risks. Loss of body-condition score between calving and 45 days after calving was associated with increased days open and days-to-first insemination. Cows with body-condition scores < 2 after Day 45 and before first insemination were less likely to be inseminated and become pregnant compared with cows that had higher body condition. Milk yield, mastitis, lameness, milk fever and genital infection were associated with a reduction in reproductive efficiency. The results indicated that loss of body-condition and actual body-condition scores before conception or first insemination or both can be used as a prognosis for days open and days-to-first insemination in dairy herds.

Preliminary Analysis of Tetracycline Residues in Marketed Pork in Hanoi, Vietnam

Abstract:  A cross‐sectional survey was designed to investigate the proportion of tetracycline residues in marketed pork in suburb and urban districts in Hanoi. A total of 290 raw muscle samples were randomly collected from open markets in these districts. The samples were qualitatively screened for tetracycline residues using the agar inhibition test, and Bacillus cereus (ATCC 11778) as the reference strain. The inconclusive samples were then analyzed using high‐performance liquid chromatography (HPLC). The positive samples from either test were defined as positive results. Overall, 5.5% of all collected samples were positive for tetracycline residues. The proportion of positive samples from shops in suburb districts was significantly (P < 0.05) different from those collected from shops in urban districts. So, the factor of region was identified as a risk factor of tetracycline residue proportion in raw pork with an odds ratio (OR) of 4.03 (95% CI = 1.12, 14.45). For the other factors, such as season, type of shop, type of abattoir, origin of meat, etc., the difference in proportion of positive samples within each factor was substantial but not statistically significant. These factors were identified as nonrisk factors. Such a high proportion may pose a potential hazard to public health, particularly since they might induce drug resistance of pathogenic micro‐organisms.

Seasonal patterns of aflatoxin M1 contamination in commercial pasteurised milk from different areas in Thailand

Aflatoxin M1 (AFM1) levels were determined in pasteurised milk from five commercial trademarks produced in different areas in Thailand. One hundred and twenty milk samples were collected from local markets in Chiang Mai province, Thailand, to evaluate AFM1 concentrations using immunoaffinity columns and high-performance liquid chromatography with fluorescence detection. The overall median AFM1 level was 0.023 µg L−1 ranging from 0.004 to 0.293 µg L−1. All trademarks had average AFM1 concentrations lower than 0.05 µg L−1, with those in Trademarks 3 to 5 being higher than Trademarks 1 and 2 (P < 0.01). All trademarks had different seasonal patterns of AFM1, even though operating in the same area. However, only Trademark 3 showed significant differences of AFM1 levels between seasons. The results suggested that farm management factors, rather than environment factors, were likely to be the main cause of AFM1 contamination in dairy products.

Comparison of transmission dynamics between Streptococcus uberis and Streptococcus agalactiae intramammary infections.

The objectives of study were to determine the transmission parameters (β), durations of infection, and basic reproductive numbers (R0) of both Streptococcus agalactiae and Streptococcus uberis as pathogens causing mastitis outbreaks in dairy herds. A 10-mo longitudinal study was performed using 2 smallholder dairy herds with mastitis outbreaks caused by Strep. agalactiae and Strep. uberis, respectively. Both herds had poor mastitis control management and did not change their milking management during the entire study period. Quarter milk samples were collected at monthly intervals from all lactating animals in each herd for bacteriological identification. The durations of infection for Strep. uberis intramammary infection (IMI) and Strep. agalactiae IMI were examined using Kaplan-Meier survival curves, and the Kaplan-Meier survival functions for Strep. uberis IMI and Strep. agalactiae IMI were compared using log rank survival-test. The spread of Strep. uberis and Strep. agalactiae through the population was determined by transmission parameter, β, the probability per unit of time that one infectious quarter will infect another quarter, assuming that all other quarters are susceptible. For the Strep. uberis outbreak herd (31 cows), 56 new infections and 28 quarters with spontaneous cure were observed. For the Strep. agalactiae outbreak herd (19 cows), 26 new infections and 9 quarters with spontaneous cure were observed. The duration of infection for Strep. agalactiae (mean=270.84 d) was significantly longer than the duration of infection for Strep. uberis (mean=187.88 d). The transmission parameters (β) estimated (including 95% confidence interval) for Strep. uberis IMI and Strep. agalactiae IMI were 0.0155 (0.0035-0.0693) and 0.0068 (0.0008-0.0606), respectively. The R0 (including 95% confidence interval) during the study were 2.91 (0.63-13.47) and 1.86 (0.21-16.61) for Strep. uberis IMI and Strep. agalactiae IMI, respectively. In conclusion, the transmission parameter and R0 values were not different between both pathogens; however, the duration of infection for Strep. agalactiae was longer than Strep. uberis. These suggest that Strep. uberis may have a different transmission dynamic compared with Strep. agalactiae.

Factors in Dry Period Associated with Intramammary Infection and Subsequent Clinical Mastitis in Early Postpartum Cows

The objective of this study was to determine cow characteristics and farm management factors during the dry period associated with early postparturient intramammary infection (IMI) and subsequent clinical mastitis (CM). Data were collected three times: before drying off (P1), during the dry period (P2), and 5 to 14 days after calving (P3), using questionnaires and farm investigation. Milk samples were aseptically collected for bacterial identification at P1 and P3. Factors associated with IMI and CM were analyzed using multiple logistic regression models. The final model showed that IMI in early postpartum was significantly associated with full insertion of dry cow antibiotic, dry cows in barns with a combination of tie and free stalls, body condition score (BCS) in dry period and after calving, and milk yield before drying off. For IMI cows, factors significantly associated with clinical expression of mastitis were having daily barn cleaning, teat disinfected with alcohol before administration of dry cow therapy, BCS before drying off, milk yield before drying off, and days in milk at drying off. In conclusion, both cow and farm management factors are associated with the IMI rate and subsequent expression of clinical signs of mastitis in early postpartum cows.

Aflatoxin B1 Contamination of Dairy Feeds after Storage in Farm Practice in Tropical Environmen

　The objective of this study was to determine the contamination of aflatoxin B1 (AF-B1) when keeping various dairy feeds in a farm environment. The study was carried out from March to May 2011 and involved 63 small holder dairy farms belonging to a single dairy cooperative in Chiang Mai province, Thailand. All feed samples used for milking cows including 4 commercial concentrates (CC1 to CC4), by-products from local corn processing factories fermented in plastic bags (SIL), and corn and cob meal or corn dust (CCD). Feed samples were collected 2 times at before and after storage. Farmers were requested to store CC1 to CC4 and CCD for a month and SIL for a week using their routine on-farm storage arrangements. All samples were measured for their AF-B1 concentrations by ELISA. Results showed that AF-B1 concentrations of CC1 to CC4, SIL and CCD before storage were 5.1, 4.1, 4.0, 4.2, 5.5 and 5.5 μg/kg, respectively, and after storage the concentration of AF-B1 were 9.7, 6.5, 9.8, 12.3, 11.4 and 20.0 μg/kg, respectively. CCD at after storage was the only feed that had mean level more than 20 μg/kg. Concentrations of AF- B1 at before storage in all feeds were significantly lower than after storage (P<0.01), and the increased ratio of AF-B1 levels was approximately 2 to 3 times. The study concluded that increased AF-B1 levels are related to feed types and farm conditions.

Use of blue-greenish yellow fluorescence test on feeds and its association with aflatoxin M1 contamination in bulk tank milk.

The objectives of this study were to use the blue-greenish yellow fluorescence (BY) test for aflatoxin M1 (AFM1) contamination in bulk milk and to examine the association between AFM1 contamination and environmental and feed management factors. The study was conducted March to May of 2011 with samples from 82 small holder dairy farms belonging to a single dairy cooperative in Chiang Mai province, Thailand. On the day of milk sample collection, samples of all feed used for milking cows and data on feed characteristics, feed management, and environmental factors also were collected at each farm. High-performance liquid chromatography was used to determine AFM1 concentrations in milk samples, and samples with AFM1 concentrations above the limit of detection were considered AFM1 contaminated. Fishers exact tests were used to determine the association between AFM1 contamination in milk and farm management factors, feed management factors, and fungal contamination in feeds (as determined with the BY test). A multilevel logistic regression model was used to create the final model of factors associated with AFM1 contamination in milk. Feeds with fungal contamination (as determined by the BY test), high levels of cracked particles of commercial concentrate pellets, sunlight in the feed storage room, storage of commercial concentrates on the farm for more than 1 month, and more than 5% difference in relative humidity between the feed storage room and the barn holding lactating cows were associated with AFM1 contamination in milk. The BY test was useful for screening cattle feed for fungal contamination, and the results of this test in conjunction with other factors can be used to monitor and prevent AFM1 contamination in milk on small holder dairy farms.