D. Vaillancourt

Determination of gestational age in sheep and goats using transrectal ultrasonographic measurement of placentomes

Three experiments were conducted to determine gestational age in the ewe and doe by measuring placentomes with a B-mode ultrasonograph and a 5 MHz transducer. Transrectal measurements were obtained by placing the female over a bale of hay. In Experiment 1, ewes (n = 12) and does (n = 15) were examined by transrectal ultrasonography every week from breeding to parturition to determine the growth pattern of placentomes during pregnancy. In Experiment 2, placentomes from 132 ewes and 169 does were measured between 30 and 90 d of gestation. A linear regression relationship between fetal age in days and placentome size in mm was calculated and adjusted for does (gestational age = 28.74 + 1.80PL + e, r(2) = 70.34) and for ewes (age = 47.98 + 0.62PL + e, r(2) = 15.59). In Experiment 3, the placentomes of 63 does were measured to validate this relationship by using linear regression. Gestational age was determined correctly in 66% of the does, with a range of +/- 7 d and in 96% with a margin of +/- 14 d. In conclusion, transrectal ultrasonography allowed for the measurement of placentome size, which increased rapidly during the first 70 to 90 d of gestation in ewes and does. In ewes, however, there was a poor correlation of placentome size with gestational age, while in goats, measurement of placentomes could be used along with pregnancy diagnosis by transrectal ultrasonography as an indication of gestation age.

Pathophysiology of the puerperal period: Relationship between prostaglandin E2 (PGE2) and uterine involution in the cow

Abstract Eighteen Holstein cows were randomly assigned to a control group or a treatment group on the day after parturition (Day 0). The treatment started on Day 10 and consisted of intrauterine infusion of 20 μg of 16,16-dimethyl PGE2 (dPGE2) in 6 ml of sterile physiologic saline or saline alone (control) twice a day, for 7 days. Palpation per rectum was performed twice weekly to assess utero-ovarian morphological changes. Blood samples were collected before, during and after the treatment for the assay of 13,14-dihydro-15 keto-PGF2α (PGFM), 13,14-dihydro-15 keto-PGE2 (PGEM), and progesterone concentrations and the proliferative activity of peripheric lymphocytes in vitro. At 20 ± 1 days post partum, animals were slaughtered and the genital tract was evaluated macroscopically. Caruncles from both horns were taken for measurement of tissue content of PGF2α and PGE2, caruncles from the former gravid horn were taken for in vitro culture. Endometrial secretions were taken for bacteriology and assay of immunoglobulins (Igs). Treatment with dPGE2 affected many of the macroscopic characteristics used to evaluate uterine involution such as the tone (P Actinomyces pyogenes . The ratio of plasma prostaglandin concentration (PGFM/PGEM) was affected by treatment. After in vitro culture of caruncular tissue for 6 hours there was no significant difference between the two groups for the synthesis of PGF2α and PGE2. These results suggest that PGE2 impedes uterine involution in the cow.

Seasonality and variability of the interestrous interval in the bitch

Records from two breeding colonies (A and B) located near each other were analyzed for this experiment. Colony A consisted of 19 bitches (8 Maltese, 5 Yorkshire, 3 Lhasa Apso, and 3 Bouvier des Flandres), while Colony B consisted of 48 Beagle bitches. A total of 126 interestrous intervals (141 estrous cycles) from Colony A were reviewed to quantitate the variability of the interestrous interval. Analysis of variance showed that the degree of variation of the estrous cycle length within bitches (65%) was about twice the degree of variation of means of the estrous cycle length among bitches (35%). It was found that the estrous cycle length is extremely variable, and it cannot be used to predict the next estrus in a single bitch, although some bitches were very consistent. The seasonal and monthly distribution of estrous cycles throughout the year was also analyzed from bitches kept in Colonies A and B for a total of 210 estrous cycles. The data were collected over a four-year period. A seasonal pattern was observed when the cumulative distributions over years were analyzed. A higher frequency of estrous cycles was observed during winter and summer. This seasonality pattern was not observed when individual years were analyzed separately. However, the overall probability that an estrus would occur at any month of the year was the same for each month (1/12) when cumulative distribution over years were analyzed.

Metabolism of arachidonic acid by caruncular and allantochorionic tissues in cows with retained fetal membranes (RFM)

The metabolism of arachidonic acid (AA) by caruncular and allantochorionic tissues and its regulation was studied in normal cows (n = 13) and those with retained fetal membranes (RFM; n = 9). Tissues were taken via the vagina about 6 hours postpartum and incubated for 6 hours in minimum essential medium containing tritiated AA alone or in the presence of oxytocin, platelet activating factor (PAF), epidermal growth factor (EGF) or ionophore calcium (A23187). The metabolites of AA were separated by reverse phase-high pressure-liquid chromatography. Tissue concentrations of prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) and plasma 13,14-dihydro-15-keto-PGF2 alpha (PGFM) concentration were also measured by radioimmunoassay. For caruncular tissue, less thromboxane B2 (TXB2) and more 6-keto prostaglandin F1 alpha (PGIM) was synthesized in tissue from the animals with RFM than in the controls. Oxytocin, PAF, EGF and A23187 increased only PGIM production in the control animals; A23187 also decreased TBX2 synthesis. For the allantochorion, more PGE2, leukotriene B4 (LTB4) and PGIM and less TXB2, PGF2 alpha and hydroxyecosatetranoic acids (HETE) was synthesized in tissue from cows with RFM than from animals that delivered normally. All of the substances used in this study increased PGIM, PGF2 alpha and LTB4 and decreased TXB2 production by the allantochorionic tissue in control animals. The metabolism of AA by the allantochorionic tissue seems quantitatively under hormonal control. The metabolism of AA at the level of both maternal and fetal components of the placenta in cows with RFM differed from that seen in animals that expelled the membranes normally.

Comparison of a leukocyte esterase test with endometrial cytology for diagnosis of subclinical endometritis in postpartum dairy cows.

The objective was to compare a leukocyte esterase (LE) test with endometrial cytology (EC) for diagnosis of subclinical endometritis in dairy cows. The relationship between subsequent fertility and the uterine (Ut) and cervical (Cx) leukocyte esterase activity was determined by the odds of pregnancy by 90 days in milk (DIM). Holstein cows (N = 218) without clinical endometritis and between 21 and 47 DIM from five commercial dairy herds were sampled for uterine and cervical leukocyte esterase activity and EC by cytobrush. To test the effect of time, cows were grouped into early (21-31 DIM) and late (32-47 DIM) animals. There was a slight agreement between UtLE and CxLE (weighted κ = 0.37). The percentage of neutrophils was correlated with esterase score either from the uterus (UtLE; P = 0.0001) or cervix (CxLE; P = 0.002). The percentage of neutrophils on EC (P < 0.001), the UtLE score (P < 0.0001), and the CxLE (P = 0.0009) diminished as DIM increased. Neither CxLE nor UtLE were statistically associated with pregnancy at 90 DIM. However, between 32 and 47 DIM, the percentage of neutrophils on EC and odds of pregnancy at 90 DIM were associated (P = 0.04). For the same interval, based on receiver/response operating characteristics analysis, the optimal cutoff was >6.7% neutrophils to classify cows with subclinical endometritis. In conclusion, uterine LE activity was correlated with percentage of neutrophils as determined by EC, but not with odds of pregnancy. Subclinical endometritis (>6.70% neutrophils) diagnosed by EC between 32 and 47 DIM was associated with reduced odds of pregnancy.

Effect of bacterial cell wall and lipopolysaccharide on arachidonic acid metabolism by caruncular and allantochorionic tissues from cows that calved normally and those that retained fetal membranes.

Immunoactive eicosanoids may have a role in both placental separation and uterine involution in cattle. In the present study, we examined the effects of bacterial cell wall preparation and endotoxins on in vitro prostaglandin synthesis and arachidonic acid (AA) metabolism by caruncular and allantochorionic tissues. Placentomes were obtained about 6 h post partum from cows that delivered normally (n = 10) or those with retained fetal membranes (n = 4); the tissue explants were incubated for 6 h in the presence of labeled or nonlabeled AA. Prostaglandin F(2alpha) (PGF(2alpha)) and E(2) (PGE(2)) were measured by radioimmunoassay, and labeled AA metabolites were separated by reverse phase-high pressure-liquid chromatography. There was no effect of bacterial cell wall preparations or endotoxins on in vitro caruncular PGF(2alpha) secretion. However, bacterial products increased caruncular PGE(2) secretion in both cows that delivered normally and those with retained fetal membranes. For normal delivery cows caruncular tissue, bacterial product also increased leukotriene B(4) (LTB(4)) and decreased both thromboxane B(2) (TXB(2)) and hydroxy-eicosatetranoic acids (HETE) in vitro secretion. For the allantochorion, bacterial products increased in vitro PGF(2alpha) secretion only in cows that delivered normally and increased PGE(2) secretion essentially in cows with retained fetal membranes. In general, 6 keto PGF(1alpha) was the main metabolite secreted by both allantochorionic and carucular tissues. However, in cows with retained fetal membranes, PGE(2) became the most important metabolite secreted by allantochorion, especially in the presence of endotoxin. In conclusion, these results suggest that bacteria found in the early postpartum uterus or their endotoxin affect primarily caruncular and allantochorionic PGE(2) synthesis.

Estrus induction with prostaglandin F2α, cloprostenol or fenprostalene during the normal estrous cycle, superovulation and after embryo collection

Holstein heifers used as embryo donors were treated with three luteolytic agents (PGF2alpha, cloprostenol, fenprostalene) during the normal estrous cycle, superovulation or after embryo collection to determine the interval from treatment to estrus. A similar return-to-estrus interval was observed for each luteolytic agent among the three groups of heifers. Nevertheless, after embryo collection, fenprostalene had a tendency to induce the longest delays (p = 0.08). This tendency is supported by a higher proportion of delayed luteolysis and more heifers showing estrus later than 11 d post treatment. Also, during normal estrous cycles, 5/10 and 0/8 fenprostalene- and cloprostenol-treated heifers, respectively, showed progesterone concentrations higher than 1 ng/mL 48 h after treatment. Regardless of the luteolytic agent used, estrus was induced earlier (P < 0.005) during superovulation than when heifers were treated between Days 9 to 16 of the normal estrous cycle or after embryo collection. However, the return-to-estrus interval was similar between heifers treated during superovulation and those treated between Days 6 to 8 of the normal estrous cycle. After embryo collection, intervals before the return to estrus increased with the number of Corpora lutea (CL) palpated except in the nonresponding group (0 to 1 CL), which returned to estrus later than the low responding group (2 to 4 CL).