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Biomedical subjects

R B Hillman

Publications and source records attributed to R B Hillman.

At least 19 recordsLinked to original sources
PubMed1989

Culture of equine trophoblastic vesicles in vitro.

Trophoblastic vesicles have been used to study early embryonic development and maternal recognition of pregnancy in domestic animals. The purpose of this study was to characterize the formation of trophoblastic vesicles from Day-12 to Day-16 equine conceptuses. Conceptuses (n = 19) were collected nonsurgically from mares, the capsule was removed, and the conceptus (trophoblast and inner cell mass) was dissected into 2- to 4-mm fragments. Conceptus fragments were cultured in either Ham's F10 (HF10) or Minimum Essential Media (MEM) with 10% fetal bovine serum (FBS) in 24-well plates. Plates were incubated at 37 degrees C in a humidified atmosphere of 90% N(2), 5% O(2), and 5% CO(2) and were examined at 48 and 96 h for the number and diameter of trophoblastic vesicles formed. There was no significant difference (P > 0.1) between HF10 and MEM in the diameter of trophoblastic vesicles at 48 or 96 h of culture. There was, however, a significant increase (P < 0.01) in the number of trophoblastic vesicles per conceptus between 48 and 96 h of culture for HF10 and MEM. The mean diameters of trophoblastic vesicles after 96 h in culture were 396.4 +/- 19.9 mum and 415.0 +/- 12.0 mum for HF10 and MEM, respectively. Histologic sections of trophoblastic vesicles revealed a bilaminar structure consistent with the presence of trophectoderm and endoderm. Squash preparations of trophoblastic vesicles contained cells similar to those recognized in squash preparations of fresh conceptuses. Areas of increased cell density that resembled the inner-cell mass were seen in both fresh trophoblastic vesicles and in sections of trophoblastic vesicles. Equine trophoblastic vesicles may be useful to further the study of early embryonic development and pregnancy recognition in mares.

Journal Article↗
PubMed1989

Plasma prolactin concentrations in mares and their neonates after oxytocin induction of parturition.

Studies were undertaken to investigate the effects of oxytocin induction on prolactin release in term (Group II) and preterm (Group III) mares and to compare these effects to spontaneously foaling mares (Group I). Since physiological concentrations of prolactin in blood have not been measured in the neonatal foal, experiments were designed to monitor prolactin in the cord artery and jugular blood of the foals from all groups of mares. Although prolactin levels varied in term mares (Group I and II) during the last 11 days of pregnancy, an increase was observed between Day -6 and Day 0 (2.7 and 11.9 ng/ml respectively; P less than 0.1). The average concentration of prolactin over the last 4 days (Days -3 to 0) had increased by 40% when compared to the average concentration on Days -6, -5, and -4. These findings indicate a rising trend which appears to occur concomitantly with changes in concentrations of 2 mammary components tested, sodium and potassium. Prolactin concentrations did not significantly increase in term mares after oxytocin treatment or in spontaneously foaling mares. However, the preterm induced mares had higher prolactin concentrations during the first stage of labor (19.3 +/- 7.2 ng/ml) than prior to treatment with oxytocin (4.7 +/- 2.0 ng/ml; P less than 0.01). Levels of prolactin in all groups significantly declined by 20-min post-placental expulsion. For the first 30 min after birth, prolactin concentrations in foals from oxytocin-induced mares appeared to be 2-fold higher than those from spontaneously foaling mares. Thereafter, prolactin values declined to baseline values by 48 hrs. When comparing cord arterial plasma with cord venous plasma in each group, prolactin concentrations were similar. However, the average prolactin levels in both the cord artery and vein appeared higher (ave: 1.1 ng/ml) in Group II and III than in Group I (less than 0.5 ng/ml). From these results, the authors suggest that 1) prolactin may have a role in regulating mammary secretory products in mares just prior to parturition; 2) oxytocin may increase prolactin secretion in preterm induced mares; 3) oxytocin induction may have a short term effect to increase circulatory prolactin concentrations in neonates in utero regardless whether their dams were treated preterm or term.

Animals↗
PubMed1988

The relationships among palpator experience, milk progesterone concentration and estrus and fertility in cows with palpable corpora lutea treated with cloprostenol.

Two hundred and fifty-one cows fresh at least 37 days with normal reproductive tracts and palpable ovarian structures which clinicians believed to be corpora lutea and which were presumed to be producing progesterone were treated with 500 micrograms of cloprostenol. The cows were stratified into three groups based on milk progesterone concentrations in whole milk samples taken at the time of examination. The low group had milk progesterone concentrations less than or equal to 1 ng/ml, the intermediate group had milk progesterone concentrations between 1 and 3 ng/ml, and the high group had milk progesterone concentrations greater than or equal to 3 ng/ml. The proportion of cows in each group inseminated within 5 days of treatment and the fertility at that breeding were compared. There were no significant differences among the groups with respect to the proportion of cows that came into estrus within 5 days. However, the conception rate of the high group (54%) was significantly greater than that of the intermediate group (26%). To study the relationship between practitioner experience and diagnostic accuracy the proportion of cows with low, intermediate and high concentrations of progesterone selected by clinicians with more than 3 years experience was compared to that for clinicians with 3 years of experience or less. Less experienced clinicians were significantly more likely to make a false positive diagnosis of functional luteal tissue in cows with palpable ovarian structures than were more experienced clinicians.

Animals↗
PubMed1988

Atypical actinobacillosis granulomas in cattle.

Actinobacillus lignieresii is well recognized as the cause of "wooden tongue." We have encountered Actinobacillosis as the cause of granulomas in unusual locations. These lesions have been confused with neoplasms, nasal polyps, or exuberant granulation tissue. Four such cases constitute this report.

Actinobacillosis↗
PubMed1987

Survival of equine embryos transferred to normal and subfertile mares.

To test the hypothesis that an abnormal uterine environment was a cause of early embryonic loss in subfertile mares, morphologically normal embryos were transferred to normal mares (n = 20) and subfertile mares (n = 20), and embryo survival rates were compared. Embryos were recovered nonsurgically at Days 7 to 8 postovulation and transferred surgically to normal and subfertile mares that had ovulated on the same day or within 2 d after a donor. Survival of transferred embryos was monitored by ultrasonography of the recipient mare's uterus from Day 9 through Day 28 postovulation. There were no significant differences (P > 0.5) in the embryo survival rates at Day 12 (11 20 vs 9 20 ) or Day 28 (10 20 vs 8 20 ) for normal or subfertile mares, respectively. The uterine environment of subfertile mares was apparently adequate to support the development of transferred embryos from Days 7 or 8 through Day 28 postovulation.

Journal Article↗
PubMed1987

Avulsion of the bovine prepuce from its attachment to the penile integument during semen collection with an artificial vagina.

Avulsion of the prepuce (AP) from the penile integument during intromission into an artificial vagina (AV) is the most common injury involving the penis and prepuce of bulls collected for the production of frozen semen at artificial insemination (AI) centers. We observed clinical cases at two AI centers. Because temporary loss of seminal collections from genetically superior bulls occurs and the possibility of impotency exists, the economical loss from AP is significant. Surgery, rather than a nonsurgical procedure, is the preferred method for repair of AP if the diagnosis occurs on the same day as the injury. After injury, seminal collection is avoided. The bull can then begin a conditioning program prior to returning to a normal semen collection schedule. A specific etiology for AP remains undetermined; however, many variables potentially involved in its occurrence are known. Bulls with good libido following 4 to 5 yr of sexual inactivity are particularly susceptible to AP. No genetic predisposition was observed. At present, we believe that AP is caused by many factors and that implementing preventive measures does help.

Journal Article↗
PubMed1987

Reproductive patterns in cyclic and pregnant thyroidectomized mares.

Three Quarter-horse mares were thyroidectomized at about 1.5 years of age. Three similar intact mares served as controls. The study continued through two breeding seasons. The thyroidectomized mares were lethargic, rear limbs were oedematous and hair coats were coarse. They displayed a tranquil oestrous behaviour when exposed to a stallion and were only mildly antagonistic when not in oestrus. Length of oestrous cycles varied but most often they were 19-24 days long. Duration of oestrus (mean +/- s.e.m.) for the control and thyroidectomized mares was 12.9 +/- 2.9 and 11.7 +/- 2.2 days respectively (P greater than 0.05). The peak of LH during oestrus was as high as 60 ng/ml blood serum with no difference between the two groups. Peak progestagen on Day 7 after ovulation for controls was 9.0 +/- 1.6 ng/ml and was not different (P greater than 0.05) from the peak of 6.3 +/- 1.7 ng/ml for thyroidectomized mares on Day 8. Pregnancy was achieved in both groups of mares, including the use of semen from a thyroidectomized stallion. Thyroxine was detectable in one pregnant thyroidectomized mare during the last two-thirds of pregnancy only.

Animals↗
PubMed1986

Pregnancy rates at Days 2 and 14 and estimated embryonic loss rates prior to day 14 in normal and subfertile mares.

Pregnancy rates at Days 2 and 14 postovulation were determined for 15 normal mares and 15 subfertile mares. Embryonic loss rates were estimated by the difference in the Day 2 and Day 14 pregnancy rates. Mares were artificially inseminated with the pooled ejaculates from three stallions, and the embryonic vesicle was detected with ultrasonography at Days 9, 10, 12 and 14. Mares were short-cycled with prostaglandin F(2) alpha (PGF(2alpha)) and rebred to the same stallions, and the Day 2 pregnancy rates were determined by recovery of cleaved ova (embryos) from the surgically excised oviducts. Significantly more (P < 0.01) normal versus subfertile mares were pregnant at Day 14 (12 15 vs 3 15 ). There was no significant difference in the Day 2 pregnancy rate for normal versus subfertile mares (10 14 vs 11 14 ). There were no significant differences (P > 0.5) in the mean number of blastomeres per embryo or in the mean diameter of embryos recovered at Day 2 from normal or subfertile mares. The estimated embryonic loss rate was significantly lower (P < 0.01) for normal verusus subfertile mares (0 10 vs 8 11 ). Fertilization rates were similar for normal and subfertile mares; however, subfertile mares had a higher embryonic loss rate prior to Day 14 postovulation.

Journal Article↗
PubMed1986

Recovery and evaluation of embryos from normal and infertile mares.

To evaluate embryo transfer as a possible method to circumvent infertility in mares, embryos from 14 normal and 14 infertile mares were collected three times and examined. Fewer flushes (p less than 0.05) from normal than infertile mares (1/42 vs 9/42) contained only abnormal embryos whereas more flushes (p less than 0.05) from normal than infertile mares contained one or more normal embryos (28/42 vs 8/42). More flushes (p less than 0.05) from normal than infertile mares contained embryos (29/42 vs 17/42). The embryo diameters (mm) at either day-7 or day-8 post ovulation were greater (p less than 0.01) for normal than infertile mares (day 7: 07 +/- 0.08 vs 0.3 +/- 0.07; day 8: 1.1 +/- 0.18 vs 0.7 +/- 0.23). Six of the 10 (60%) flushes that contained only abnormal embryos were recovered from ares with positive uterine cultures or moderate to severe endometritis. The embryos recovered from normal mares were greater in quantity and better in quality.

Animals↗
PubMed1985

Path model of reproductive disorders and performance, milk fever, mastitis, milk yield, and culling in Holstein cows.

Path analysis was used to model the direct and indirect relationships among age, previous lactation yield or estimated transmitting ability for milk, body weight, days dry, reproductive disorders, milk fever, mastitis, reproductive performance, current milk yield, and culling. Prospective data were from 784 primiparous and 2,066 multiparous Holstein lactations from 33 herds. Heifers that were older, of lighter weight, or who had lower estimated transmitting ability for milk had more problems, less milk, and poorer survival. Dystocia in heifers had several detrimental consequences including 2.9 to 4 times more retained placenta, metritis, and culling and +7.4 d more to first service. Cystic ovaries were associated directly with 376 kg greater milk yield and with a 16.5-d delay in first service. Failure to conceive at first service and mastitis increased risk of culling 5.2 to 10 times. In multiparous cows, milk fever increased risk of reproductive disorders by 1.6 to 4.2 times and indirectly contributed to poor breeding performance and increased culling. Risk of culling was increased 2.1 to 3.7 times directly by mastitis and dystocia and by poor breeding performance.

Age Factors↗
PubMed1984

Rates of diagnosis of six diseases of Holstein cows during 15-day and 21-day intervals.

The lactations of 3,172 Holstein dairy cows were divided into intervals of 15 and 21 days. The numbers of new diagnosis of metritis, cystic ovary, miscellaneous reproductive disorders, mastitis, left displaced abomasum, and milk fever in each interval were counted. The numbers of cows at risk in each interval were also counted. A cow was at risk if she was still milking, in the herd, and a diagnosis had not already been made for that condition in that lactation. A cow was also only at risk of a reproductive diagnosis if she was not pregnant. For each interval, the incidence rate of new diagnosis was calculated by dividing the number of new diagnoses by the number of cows at risk.

Abomasum↗
PubMed1983

Association of parturient hypocalcemia with eight periparturient disorders in Holstein cows.

The association between parturient hypocalcemia and 8 periparturient disorders (dystocia, retained fetal placenta, metritis, left displaced abomasum, foot problems, ketosis, mastitis, and coliform mastitis) was evaluated in 33 Holstein dairy herds (2,190 cows) that calved from March 1981 through February 1982. There were highly significant (P less than 0.0001) associations between parturient hypocalcemia and dystocia, retained fetal placenta, ketosis, and mastitis. The odds ratios (multiplicative increases in occurrence) for these associations were 6.5, 3.2, 8.9, and 8.1, respectively. There was a significantly (P less than 0.03) association between parturient paresis and coliform mastitis (odds ratio, 9.0). There was a tendency for association with left displaced abomasum (odds ratio, 3.4; P less than 0.06).

Abomasum↗
PubMed1982

Chlorpyrifos (Dursban 44r) toxicity in dairy bulls.

The toxicity of Dursban 44 (chlorpyrifos) in dairy bulls in two large Northeastern A.I. bull centers is reported. One hundred eighty-five (185) bulls were treated at the first center and two hundred thirty-two (232) at the second. The application of this product resulted in the death of seven and one bulls, respectively. The knowledge and experience gained at the first center resulted in rapid diagnosis and specific treatment at the second and was felt to be a significant reason for the lower death rate. Typical, clinical signs of organophosphate poisoning were not exhibited in these two outbreaks. Specific diagnosis, treatment and the course of chlorpyrifos poisoning in Holstein bulls are discussed.

Animal Husbandry↗
PubMed1981

Metabolic abnormalities associated with rupture of the urinary bladder in neonatal foals.

Rupture of the urinary bladder was diagnosed in 4 neonatal male foals. Marked hyponatremia, hypochloremia, and hyperkalemia developed in all 4 cases, and the electrolyte abnormalities were considered to be of potential diagnostic value. Blood urea nitrogen concentration was normal or only slightly higher than normal in 3 of 4 cases and therefore was not a reliable diagnostic test.

Animals↗
PubMed1980

Temperature of the artificial vagina and its effect on seminal quality and behavioral characteristics of stallions.

Stallion semen was collected, using artificial vaginas at 44 to 46, 48 to 50, and 52 to 54 C, to study the effects of temperature on seminal quality and sexual behavior. The temperature of the artificial vagina had no significant effect on motility, gel volume, gel-free seminal volume, total seminal volume, pH, number of mounts per ejaculate, total time to ejaculation, or seminal temperature. Spermatozoa were collected, then exposed to water-bath temperatures of 38, 45, 49, or 53 C for 1 minute. Mean motility was similar after exposure to temperatures of 38 or 45 C, but exposure to temperatures of 49 or 53 C resulted in a significant decrease (P < 0.05) in spermatozoal motility with each increase in temperature. Thus, it was concluded that spermatozoa exposed to temperatures greater than 45 C may be irreversibly damaged.

Animals↗
PubMed1980

Induction of abortion in mares with equimate: effect on secretion of progesterone, PMSG and reproductive performance.

Thirty-two light-horse mares were confirmed to be pregnant and assigned to one of four treatments: (1) injected with 250 micrograms of Equimate on day 70 and again on day 77 if abortion had not occurred; (2) injected with 250 micrograms of Equimate on day 70 and every 24 hr until abortion occurred (maximum four injections); (3) injected with 250 micrograms of Equimate on day 70 and every 12 hr until abortion (maximum eight injections); and (4) injected with 250 micrograms of Equimate once only on day 35 of gestation. Mares were observed four times daily for incidence of abortion or side effects. Estrual behavior was monitored daily and follicular activity either daily or every third or fourth day until estrus and ovulation. Samples of jugular blood were obtained at 0600 hr day -1 and every 6 hr until the first day of estrus after abortion, or for 2 weeks after abortion if estrus had not occurred, or for 1 week after treatment for mares that had not aborted. A single injection of Equimate terminated pregnancy in all but one mare injected on day 35, but none of the mares given an injection on day 70 and 77 aborted. Multiple injections of Equimate beginning on day 70 of gestation terminated pregnancy in all mares. Fewer (P less than .05) injections were required for abortion of mares injected daily. During the immediate week post-treatment, concentrations of progesterone decreased (P less than .05) in all mares injected with Equimate, but overall concentrations were greater (P less than .05) for mares injected once on day 70 than for those in the other three groups. Equimate did not affect secretion of PMSG in the day 70 group of mares. Estrus and ovulation after abortion were delayed (P less than 0.05) for mares injected daily or twice daily beginning on day 70 compared to those injected once on day 35. Thus, rebreeding of these mares during the same breeding season in which they were aborted would be difficult.

Abortifacient Agents↗