No adverse effect of confirmation of ovulation by rectal palpation and ultrasonography after artificial insemination on formation, development, and function of the corpus luteum and conception rate in cows.

The effect of confirmation of ovulation by rectal palpation and ultrasonography after artificial insemination (AI) on the development of the corpus luteum (CL) and conception rate was investigated in cows. A total of 90 clinically healthy Holstein-Friesian dairy cows were examined in this study. After AI, the cows were divided into three groups (30 cows per group). In Group I, ovulation was confirmed by rectal palpation at 24 h after AI. In Group II, ovulation was confirmed using transrectal ultrasonography 24 h after AI. In Group III, ovulation was not confirmed after AI. Day 0 was defined as the day when ovulation was confirmed in Groups I and II, and as the day after AI was performed in group III. Transrectal ultrasonography was performed on days 3, 5, 7, and 14 to measure the CL diameter, tissue area, and CL blood flow area, and the ratio of CL blood flow area to CL tissue area was calculated. On the day of CL measurement, blood samples were collected to determine the plasma concentrations of progesterone (P4) and estradiol-17ß (E2). Pregnancy was diagnosed at 28 and 60 days after AI. A high conception rate of approximately 80% was achieved in Groups I and II, in which confirmation of ovulation was conducted. There were no differences in the diameter, tissue area, or blood flow area of the CL between the three groups. These results indicate that the confirmation of ovulation by rectal palpation and transrectal ultrasonography did not affect the formation and function of the CL or conception rate.

Effect of high-concentrate corn grain diet-induced elevated ruminal lipopolysaccharide levels on dairy cow liver function.

A high-concentrate diet destroys gram-negative bacteria in the cattle rumen, leading to elevated ruminal lipopolysaccharide (LPS) levels. LPS causes liver inflammation through the hepatic portal vein but little is known about the effects of rumen-derived LPS on liver function and the reproductive organs. In this study, we determined the effect of increasing rumen fluid LPS levels on liver function and genital LPS levels. Cows were assigned to control (CON; n=5) and high-concentrate diet (HC; n=7) groups. We observed that the ruminal LPS and haptoglobin (Hp) levels were significantly higher and albumin levels were lower in the HC group than in the CON group. In the HC group, The Hp levels and aspartate transaminase (AST) activity were significantly higher and the total cholesterol levels were significantly lower after high-concentrate diet feeding than before feeding. No differences were observed in LPS levels in the peripheral veins, hepatic veins, hepatic portal vein, uterine perfusate, and follicular fluids between the groups. In all samples, the LPS level in the hepatic portal vein blood positively correlated with the AST activity and serum amyloid A level. In conclusion, our results indicate that high-concentrate diets do not have a direct effect on the reproductive organs upon a moderate ruminal LPS level increase. However, an increased ruminal LPS influx into the liver might affect negatively liver function.

An investigation of the time period within which frozen-thawed semen delivers a high conception rate in lactating dairy cows.

We determined the length of time within which frozen-thawed semen delivered a high conception rate in present-day lactating dairy cows. The cows utilized were a total 100 milking Holstein-Friesian cows kept in tie-stall style farms. We carried out artificial insemination (AI) during the periovulatory period at a predicted time based on ovulation, and checked ovulation at 6-h intervals after AI. The period from AI to ovulation ranged from 48 h (i.e., 48 h before ovulation) to -12 h (i.e., 12 h after ovulation). High conception rates averaging 63.0% were obtained by carrying out AI > 6-30 h before ovulation, significantly higher than the conception rates of 30.0% (P < 0.05) and 26.9% (P < 0.01) from AI carried out earlier than 30 h before ovulation and later than 6 h before ovulation, respectively. It was concluded that frozen-thawed semen delivers a conception rate of ≥ 60% for > 24-30 h after AI, and that a conception rate of ≥ 60% can be achieved by carrying out AI 6-30 h before ovulation using frozen-thawed semen.

Prevalence and molecular subtyping of Blastocystis from dairy cattle in Kanagawa, Japan.

Blastocystis is an intestinal protist, commonly found in the human population and in a wide range of animals globally. Currently, isolates from mammalian and avian hosts are classified into 17 subtypes (STs) based on phylogeny of the small subunit rRNA gene (SSU rDNA), of which ten (ST1-9, 12) are reported in humans. ST10 is a major ST reported from livestock cattle. However, other STs including ST1, 3, 4, 5, and 6, which have the potential to be transmitted to humans, are also reported from cattle in several countries. Although a survey has been conducted previously in western Japan for livestock cattle, there is no information available regarding other parts of Japan. Therefore, this study surveyed the prevalence of Blastocystis and its STs in cattle from Kanagawa prefecture, eastern Japan. Fecal specimens, collected from 133 dairy cattle on four different farms, were subjected to a short-term xenic in vitro culture and Blastocystis were identified by microscopic examination. Seventy-two cattle were positive for Blastocystis (54.1%). Direct sequences for the partial SSU rDNA were obtained for 45 samples. Based on nucleotide sequence homology search and phylogenetic analysis, 44 isolates were identified as ST14 and one as ST10. Our study confirms the presence of these STs in dairy cattle in Japan for the first time. The STs identified here, ST10 and ST14, support previous findings that Bovidae may be the natural host for both STs.

Evaluation of criteria for optimal time AI postulated by estrous signs in lactating dairy cows kept in tie-stalls.

Relaxation of the intravaginal part of the uterus is obvious around 6 to 18 h before ovulation, and this is considered the optimal time for artificial insemination (AI), as demonstrated in recent studies. Estrous signs have been suggested as useful criteria for determining the optimal time for AI. Therefore, this study evaluated the usefulness of estrous signs, particularly the relaxation of the intravaginal part of the uterus, as criteria for determining the optimal time for AI. A Total of 100 lactating Holstein-Friesian cows kept in tie-stall barns were investigated. AI was carried out based on the criterion for the optimal time for AI (optimal group), and earlier (early group) and later (late group) than the optimal time for AI, determined on the basis of estrous signs. After AI, ovulation was assessed by rectal palpation and ultrasonographic observation at 6-h intervals. For 87.5% (35/40) of cows in the optimal group, AI was carried out 24-6 h before ovulation, which was previously accepted as the optimal time for AI. AI was carried out earlier (early group) and later (late group) than optimal time for AI in 62.1% (18/29) and 71.0% (22/31) of cows, respectively. The conception rate for the optimal group was 60.0%, and this conception rate was higher than that for the early group (44.8%) and late group (32.2%), without significance. Further, the conception rate of the optimal group was significantly higher than the sum of the conception rates of the early and late groups (38.3%; 23/60) (P < 0.05). These results indicate that the criteria postulated, relaxation of the intravaginal part of the uterus and other estrous signs are useful in determining the optimal time for AI. Furthermore, these estrous signs enable the estimations of stages in the periovulatory period.

Relationships between the appearances and changes of estrous signs and the estradiol-17ß peak, luteinizing hormone surge and ovulation during the periovulatory period in lactating dairy cows kept in tie-stalls.

Lactating Holstein-Friesian cows kept in tie-stall barn were used as subjects in this study. Rectal examination, ultrasonography and blood sampling were conducted every other day and then daily after the day on which diameter of the corpus luteum decreased. After the luteal diameter decreased for 2 consecutive days, rectal and ultrasound examinations, blood sampling, and observation of estrous signs were conducted at 6-h intervals. Most of the estrous signs became obvious with the increase in estradiol-17ß (E2) and became most remarkable 24 to 30 hours before ovulation, at which point the E2 peak and luteinizing hormone (LH) surge were achieved, and then weakened which progression to ovulation. The correlation between the intensity of four estrous signs (hyperemia and swelling of the intravaginal part of the uterus, opening of the external uterine orifice and viscosity of the cervical mucus) and the plasma E2 concentration was higher than that of three estrous signs (swelling of the vulva, contraction of the uterus, diameter of uterine horn) and the plasma E2 concentration. The relaxation of the intravaginal part of the uterus showed a unique change compared with the other estrous signs, and it became most obvious 6, 12 and 18 h before ovulation; this obviously relaxed period was consistent with the generally accepted theoretical optimal time for artificial insemination (AI), i.e., 6 to 24 h after initiation of estrus. These results suggest that observation of estrous signs by vaginoscopic examination gave useful information for detection of the optimal timing of AI in the periovulatory period in lactating dairy cows kept in a tie-stall barn.