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A database of milk progesterone profiles consisting 497 lactations in 3 dairy herds from northern and western regions of Japan was used to identify the characteristics and associated risk factors for prolonged luteal phase (PLP) and its effects on subsequent reproductive performance in high-producing Holstein cows. Milk samples were collected twice weekly and progesterone concentrations in whole milk were determined by ELISA. Herds were visited monthly and examined by vaginoscopy and transrectal palpation. Resumption of ovarian cyclicity within 35 d postpartum followed by regular cycles was considered normal. Prolonged luteal phase was defined when progesterone concentrations were ≥5 ng/mL for ≥20 d of duration in any cycle postpartum. Delay of first ovulation to 35 to 60 d (delayed first ovulation type I), >60 d (delayed first ovulation type II), a luteal phase of <14 d except in the first cycle (short luteal phase), and the absence of luteal activity >14 d between 2 cycles (cessation of cyclicity) were the other categories of abnormal ovarian resumptions considered. The overall incidence of PLP in the 3 herds was 11.9% and a significantly higher proportion of PLP was observed in the first cycle postpartum compared with the second and third cycles. Approximately 83% of the PLP were 20 to 28 d in duration, and maximum progesterone concentration was significantly higher when PLP lasted >35 d compared with PLP of 20 to 35 d in duration. Higher parity, commencement of luteal activity≤28 d postpartum, and postpartum complications significantly increased the occurrence of PLP within 90 d postpartum. Cows with PLP showed reduced conception rate to first artificial insemination (AI) and reduced pregnancy proportions within 100, 150, and 210 d postpartum. Based on survival analysis, PLP was associated with a 56% reduction in relative pregnancy rate and a 36% reduction in AI submission rate. Cows that experienced PLP had a longer interval from calving to first AI (74 d) and from calving to pregnancy (141 d) than cows without PLP (53 and 80 d), respectively. In conclusion, 11.9% of lactations had PLP, of which approximately two-thirds were seen in the first cycle postpartum. Most of the PLP were 20 to 28 d in duration. Higher parity, postpartum complications, and early commencement of luteal activity postpartum increased the risk for PLP. Occurrence of PLP adversely affected fertility by reducing pregnancy proportions and extending calving to conception interval.

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Oestrus detection error and conception rates after AI based only on secondary oestrus signs were evaluated in a high yielding, 24-h tie-stalled dairy herd with low fertility, using milk progesterone profiles. Oestrus detection was based on the secondary oestrus signs such as restlessness, swelling, congestion of vulva and clear mucus discharge. Sixty eight AI conducted after observing the secondary oestrus signs in 44 animals were included in the study. Of the 68 AI, 53 (77.9%) were conducted in the follicular phase, and 13 (19.1%) and 2 (2.9%) were carried out in the luteal phase and during pregnancy, respectively. The overall error in oestrus detection based on milk progesterone profiles was 22.1%. The oestrus detection error did not differ significantly among different secondary oestrus signs. None of the AI conducted in the luteal phase resulted in conception, whereas 20.8% of AI conducted in the follicular phase resulted in conception. No significant difference in the conception rates among the groups of cows with different secondary oestrus signs was shown. The high incidence of oestrus detection error in this study might have been caused by the detection of cows in oestrus based only on secondary oestrus signs due to the confinement of animals. In conclusion, there was a high incidence of heat detection error in the 24-h tie-stalled dairy herd and oestrus detection based only on secondary oestrus signs resulted in low conception rate.

Compared with clinical mastitis, the subclinical form of mastitis (SCM) is more common and thought to cause more economic losses to the dairy industry. The current study aimed to investigate the prevalence, risk factors of SCM, and effects on reproduction of dairy cows in major milk-producing areas of Sri Lanka. A total of 1,357 cows of selected farms in 3 regions were examined in the study. California Mastitis Test was conducted for individual cows, and a score of 2 or more for any quarter without any clinical symptoms and abnormalities in milk was considered as positive for SCM. Samples from infected animals were collected and subjected to bacteriological analysis. A pretested questionnaire was used to collect data on individual cows and herds. Risk factors associated with SCM were analyzed using binary logistic regression in generalized linear mixed models. The effect of SCM on calving to conception interval and days from calving to artificial insemination were analyzed by survival analysis using Cox's proportional hazards regression and Kaplan-Meier survival function estimates, respectively. A Poisson regression model was run to determine the effect of SCM on number of artificial inseminations per conception. The prevalence of SCM was 57.5, 11.8, and 45.5% in the regions A, B, and C, respectively. The most common pathogen was Staphylococcus aureus, with 87.1, 56.5, and 92.3% in the regions A, B, and C, respectively. Logistic regression analysis showed that parity, farming system, milking area, region, and herd significantly affect the prevalence of SCM. Subclinical mastitis during the pre-breeding period was associated with 14% increase in the chance of having a greater number of artificial inseminations per conception. Likewise, median days from calving to artificial insemination was longer in cows with SCM compared with normal cows (79 and 64 d, respectively). Therefore, SCM affected the inseminated proportion of studied cows. However, SCM was not associated with the calving to conception interval. The results revealed that the cow factors and milk hygiene play a significant role in the prevalence of SCM.

Escherichia coli is a commensal bacterium that lives in human and animal intestines. Shiga toxin-producing strains of E. coli STECs are responsible for most food-related E. coli infections. Pathogenic E. coli transmits to human bodies due to the consumption of contaminated, raw, or undercooked food. This study was conducted to identify the prevalence of E. coli contamination in edible poultry meat and meat organs in the North Western Province of Sri Lanka. A total of 250 samples consisting of chicken meat (n = 144) and edible organs (n = 106) were collected from retail shops (n = 181) and supermarkets (n = 69), in both Kurunegala and Puttlam districts. The prevalence of E. coli from 250 chicken meat samples was 66.80% (167/250); E. coli prevalence at retail shops (66.85%) was higher than that at supermarkets (66.67%) and was not statistically significant. E. coli prevalence in chicken meat and edible organs was 65.73% and 69.16%, respectively. Molecular confirmation for the positive samples was done through polymerase chain reaction (PCR) using previously designed primers. An antibiotic susceptibility test was performed according to CLSI using nine antibiotics: ampicillin, amoxicillin, chloramphenicol, ceftazidime, ciprofloxacin, cephalexin, erythromycin, gentamicin, and tetracycline. Most isolates were resistant to erythromycin (80.84%) and amoxicillin (76.05%), while the least resistance was observed for gentamicin (4.79%). This study indicates the potential public health risk associated with chicken sold at retail and supermarket levels in the North Western Province of Sri Lanka.

The assay procedure for N-acetyl-β-D-glucosaminidase (NAGase) was considered to be the most reliable, simple, and rapid enzymatic method for estimating the severity of mammary tissue damage. This study was carried out to assess the relationship of NAGase enzyme activity, California mastitis test score (CMTS) and somatic cell counts (SCC) in milk and the influence of breed, parity and age of the cow on NAGase activity. The results showed that prevalence of sub-clinical mastitis (SCM) was 74.5% (41/55) in the population of cows tested. The isolated pathogens were Staphylococcus spp. (34%, 14/41), Escherichia coli (34%, 14/41) and Streptococcus spp. (32%, 13/41). The SCC showed a significant (p<0.05) positive correlation with the activity of NAGase (R2= 0.796) and CMTS (R2= 0.709). A significant correlation was observed between the NAGase activity and SCC in SCM positive milk, where the correlation was stronger (R2= 0.748) in the former than in the latter. The parity (R2= 0.843) and age (R2= 0.758) of the cow also showed a significant (p<0.05) positive correlation with enzyme activity. The mean SCC and enzyme activity of different crossbreds of the study population did not show a significant correlation, but mean values of SCC and enzyme activity were higher when an animal was phenotypically more related to European breeds (779-1848 x103 SCC/ml;0.64-0.89 µmole/min/ml) than tropical breeds (427-534x103 SCC/ml; 0.26-0.43 µmole/min/ml). It could be concluded that, the prevalence of SCM in crossbred cows in NorthWestern Province of Sri Lanka is considerably high. The determination of NAGase enzyme activity in milk could be used as a method for early detection of SCM more accurately than CMTS and SCC.