L.-E. Edqvist

Postweaning grouped sows: effects of aggression on hormonal patterns and oestrous behaviour

Abstract The concentration of cortisol, oestradiol-17β, prolactin and the amount of social behaviour shown during oestrus were measured in three groups of three sows (Swedish Landrace×Swedish Yorkshire) grouped after weaning and correlated with aggressive behaviour. No relations between the amount of aggression received and any of the hormone levels were found. In contrast, the frequency and characteristics of the oestrous behaviour were related to the amount of received aggression; the sows that received the highest amount of aggression showed significantly less social behaviour during oestrus compared with the other sows.

Levels of prostaglandin F2α metabolites in blood and urine during early pregnancy

Kindahl, H., Basu, S., Fredriksson, G., Golf, A., Kunavongkrit, A. and Edqvist, L.-E., 1984. Levels of prostaglandin F2c ~ metabolites in blood and urine during early pregnancy. Anita. Reprod. Sci., 7: 133-148.

Effect of dose of pregnant mare serum gonadotrophin on estrus parameters, ovulation rate and peripheral progesterone concentrations in Yankasa ewes

Abstract Estrus was synchronized in 30 mature Yankasa ewes using progestagen pessaries containing 45 mg Flugestone acetate. Animals were divided into five equal groups and treated, at sponge withdrawal with 0, 250, 500, 750 and 1000 IU PMSG (i.m.). Estrus detection was conducted and plasma samples collected every other day for progesterone determination. Ovulation rates were determined by counting the number of corpora lutea on each ovary using a mid-ventral surgical approach. Intervals from sponge withdrawal to onset of estrus (h) were 44.5±4.5 (0 IU), 32.9±1.7 (250 IU), 37.8±1.1 (500 IU), 26.9±3.2 (750 IU) and 27.1±2.6 (1000 IU). Mean durations of estrus (h) were 25.0±0.6 (0 IU), 61.3±3.9 (250 IU), 12.0±4.5 (500 IU), 49.9±7.0 (750 IU) and 44.5±11.7 (1000 IU). Ovulation rates (based on number of corpora lutea) averaged 1.0±0.0, 1.3±0.3, 2.0±0.0, 5.5±0.5 and 7.0±1.2 for ewes treated with 0, 250, 500,750 and 1000 IU PMSG, respectively. Post-synchronization estrous-cycle lengths increased linearly due to PMSG treatment and were 16.5±0.5, 17.0±0.6, 18.0±0.6, 19.5±0.5 and 23.8±0.3 days for ewes treated with 0, 250, 500, 750 and 1000 IU PMSG, respectively. Plasma progesterone concentrations also showed significant treatment effects being dose dependent. Total progesterone concentrations were 15.3±2.5 (0 IU), 36.6±10.9 (250 IU), 56.1±7.7 (500 IU), 82.2±5.6 (750 IU) and 125.7±9.0 (1000 IU) (ng/ml). The results indicate the possibility to increase ovulation rates in Yankasa ewes with PMSG and to establish a direct relationship between PMSG dosage, ovulation rate and plasma progesterone concentrations.

Endocrine pattern and external oestrous symptoms at second and fourth oestrus in gilts

Abstract The peripheral blood plasma levels of LH, oestradiol-17β and progesterone were recorded during the second and fourth pro-oestrous—oestrous periods in six crossbred (Swedish Landrace X Swedish Yorkshire) gilts. The relationships between hormonal levels, external heat signs and ovarian function were studied. Blood samples were taken every third hour during the pro-oestrous—oestrous periods and during this time the heat detection was performed when blood was collected, otherwise twice daily. The ovaries were inspected by laparoscopy after the first, second and fourth oestrus. The gilts were slaughtered after the fifth oestrus and the genital organs examined. In the five gilts showing five successive regular heats the duration of the second pro-oestrus (reddening and swelling of the vulva) was significantly longer (56.4 ± 5.3 h) than that of the fourth (23.4 ± 6.3 h). The oestrus (standing reflex) duration did not differ, being 51.6 ± 5.4 h for the second and 52.2 ± 9.3 h for the fourth oestrus. The mean oestradiol-17β level was significantly increased during the fourth pro-oestrous—oestrous period (43.9 ± 0.75 pmol) as compared to the second (37.8 ± 0.73 pmol). The LH level was also significantly higher during the fourth (1.61 ± 0.08 μg /l) than during the second pro-oestrous—oestrous period (1.25 ± 0.08 μg /l). There was, however, no difference in the duration of elevated oestradiol levels (> 30 pmol/l). In spite of the higher oestradiol-17β levels, the duration of the external heat signs was reduced during the fourth pro-oestrus when compared to the second. This phenomenon might be explained by a change in susceptibility of vulvar hormonal receptor mechanisms. The sixth gilt displayed three normal heats, but failed to show standing reflex and to ovulate thereafter. The hormonal patterns were normal during the second pro-oestrous—oestrous period. At the expected fourth heat there was a rise of oestradiol but no preovulatory LH peak occurred.

Clinical and endocrine responses to pulsatile administration of gonadotropin-releasing hormone (GnRH) treatment during lactation in primiparous sows

Abstract The object of the investigation was to study the clinical and endocrine responses to pulsatile administration of GnRH by means of an automatic injection pump during the early (Days 8–15) or late lactation (Days 21–28) period in primiparous sows. A total of 22 sows were used in two experiments. In Experiment 1, 10 μg GnRH were administered intravenously by pulsatile injection in eight pairs of sows every 89 min for 7 days during the early (Group IA) or late lactation (Group IB) period. In Experiment 2, 10 μg (Group IIA) or 2.5 μg (Group IIB) GnRH were administered intravenously by pulsatile injection in three pairs of sows every 89 min for 7 days during the late lactation period. All sows responded to GnRH treatment with increased peripheral plasma levels of LH. There was no difference in the LH response between the early and the late lactation period. The LH response on the first day of treatment was greater than that on subsequent treatment days. Laparoscopic examination revealed that the follicular size increased in the majority of sows in both experiments. Concomitantly with increased follicular size, there was a gradual rise in the plasma level of oestradiol-17β. In Experiment 1, three sows in Group IA and four sows in Group IB showed lactational oestrus, but only one out of three lactational oestrous sows in Group IA ovulated while all four lactational oestrous sows in Group IB ovulated. In Experiment 2, two sows in each group ovulated during lactation, due to GNRH treatment. The present results demonstrate that lactational oestrus can be induced by pulsatile injection of GnRH every 89 min for 7 days during the early or late lactation period. The stage of the lactation did not influence the LHR response to GnRH. However, a larger number of the sows showed oestrus and ovulated as a result of GnRH treatment during the late lactation than during the early lactation period.

Influence of bovine LH tracer quality on levels of LH in GnRH-treated cows.

Chromatography of 125I-bovine LH (LER-1716-2 and USDA-I-1) by means of anion exchange high performance liquid chromatography (HPLC) revealed two main peaks of radioactivity regardless as to whether or not the tracer was initially purified on cellulose CF11. The content of radioactivity in the first peak tended to increase as the storage time of the bLH preparation, either before or after iodination, increased. The first peak of radioactivity after HPLC fractionation either with or without cellulose adsorption consisted of material with low binding ability to bLH antiserum (6.9% +/- 0.5 and 13.0% +/- 1.0, respectively) and high binding ability to ovine LH alpha antiserum (51.0% +/- 2.7 and 35.2% +/- 3.6, respectively). The average ratio of alpha-subunit immuno-reactivity to 125I-bLH immunoreactivity in this material was 7.4 +/- 0.1 and 2.7 +/- 0.2, respectively (P less than 0.001). Peaks in 125I-bLH radioactivity and 125I-bLH immunoreactivity had different elution times. Radioimmunoassays with tracers obtained from fractions derived from the first radioactive peak after HPLC chromatography (i.e. 125I-bLH-LER-1716-2) both with and without cellulose adsorption, yielded significantly lower mean plasma LH levels in GnRH-treated cows compared with the control tracer routinely purified only on cellulose CF11 (e.g. 5.7 vs. 8.2 micrograms/; 4.6 vs. 8.2 micrograms/l). Plasma LH levels in GnRH-treated cows were significantly (P less than 0.001) lower as measured by radioimmunoassay utilizing 125I-USDA-blH-I-1 tracers than by radioimmunoassays utilizing 125I-blH-LER-1716-2 tracers (i.e. either Y = 0.17 + 0.75X or Y = 1.18 + 0.60X).

Subunits of bovine lutropin. Hormonal and immunological activity after separation with reversed-phase high-performance liquid chromatography.

By means of reversed-phase high-performance liquid chromatography, we have fractionated bovine lutropin (LH) standard preparations. The highly purified NIAMDD-bLH-4 was fractionated into two components, while the less pure NIH-LH-B9 revealed three distinct peaks. The eluted material was further characterized by in vitro bioassay and by homologous radioimmunoassay for bovine LH, ovine LH-alpha and ovine LH-beta subunits. The material with the shortest retention time possessed almost no LH-activity and showed a displacement curve nearly identical with that of the ovine LH-alpha subunit. The material corresponding to the second peak exhibited 6% of the original LH-activity, and its immunoreactivity was equal to that of the ovine LH-beta subunit. Furthermore, the fractions supposed to contain the alpha and the beta subunits were rechromatographed and their aminoacid contents analyzed. The results show close similarities between the rechromatographed fractions and the pure subunits.

ABSORPTION OF TOPICALLY APPLIED HYDROCORTISONE FROM THE EYE OFTHE RHESUS MONKEY

Blood samples were collected from anaesthetized monkeys during one h a) after topical application of an eyedrop of hydrocortisone acetate suspension, b) after topical application of a drop of the vehicle alone, and c) after no application at all. Radioimmunoassay (RIA) showed a rapid and similar increase of hydrocortisone plasma levels in all 3 kinds of experiments. RIA revealed that in monkeys the anaesthetic procedure alone was sufficient to cause a considerable increase of endogenous hydrocortisone levels overshadowing any systemic absorption of topical hydrocortisone. Using tritiated hydrocortisone instead a rapid increase of systemic absorption after topical application was found. A plasma concentration of 1 % of the dose was found one min after topical instillation increasing to a maximum of 6–7% at 30 min. The half time of the slow phase of elimination was about 19 h.

Plasma prolactin during pulsatile administration of GnRH and oestrus in lactating sows

The pattern of plasma prolactin (PRL) during pulsatile administration of GnRH and oestrus in five lactating sows was studied. Sows nursing 8.2±0.4 piglets were injected with 2.5 μg or 10 μg GnRH every 89 min for 7 days beginning on Day 21 of lactation. All sows exhibited ovulatory oestrus at 6.8±0.8 days of treatment and were weaned at 34.8±1.3 days of lactation. PRL concentrations were determined in samples taken every 3 h from 09:00 to 21:00 h from Day 20 of lactation until weaning. The mean concentration of PRL was 19.2±0.8 μg 1−1 before GnRH treatment. On the first day of the treatment, PRL decreased to 13.8±0.9 μg 1−1 (P<0.001), possibly as a result of a temporary separation of the sows from their piglets for surgery. An increase in PRL concentrations (P<0.05) was observed on the second and third days of the treatment (Day 22–23) or 4–5 days before oestrus. From Day 24 until Day 32 of lactation the daily mean concentrations of PRL remained at levels similar to those occurring prior to GnRH treatment. PRL levels showed a diurnal rhythm of change with the lowest concentrations at 21:00 h.

Characterization of a thermostable LH-immunoreactive material from bovine pituitary gland

A thermostable peptide, immunologically similar to the beta-subunit of ovine lutropin, was isolated from a heated extract of bovine pituitary glands. The relative molecular mass of the peptide as well as its amino acid composition differed significantly from the lutropin subunits. Antibodies were raised to a preparation of this peptide.