Nutritionally induced relationships between insulin levels during the weaning-to-ovulation interval and reproductive characteristics in multiparous sows: I. Luteinizing hormone, follicle development, oestrus and ovulation

To get more insight in how insulin secretion patterns and corresponding insulin-like growth factor-1 (IGF-1) levels are related to luteinizing hormone (LH) secretion, follicle development and ovulation, 32 multiparous sows were fed either a dextrose plus lactose-containing diet at 4 h intervals (DL; each 150 g/day) or an isocaloric control diet at 12 h intervals (CTRL; containing soybean oil) during the weaning-to-ovulation interval (WOI). Insulin parameters (basal, peak levels and mean insulin) and IGF-1 levels during the WOI were similar for both treatments, but the insulin secretion pattern differed (related with feeding frequency and meal sizes). Oestrus and ovulation characteristics were not influenced by treatment. The LH surge was higher in CTRL compared with DL sows (3.73 vs 3.00 ng/ml; p = 0.03). Average diameter (6.5 vs 6.1 mm; p = 0.08) and uniformity (CV: 11 vs 15%, p = 0.02) of follicles ≥3 mm at day 4 after weaning was higher in CTRL compared with DL sows. Basal insulin levels were positively related with follicle diameter at ovulation (β = 0.05 mm/(μU/ml); p = 0.04) and negatively related with LH surge level (β = -0.07 (ng/ml)/(μU/ml); p = 0.01). Insulin area under the curve (AUC) (β = 0.037 (ng/ml)/1000 μU; p = 0.02) and IGF-1 levels (β = 0.002 (ng/ml)/(ng/ml); p < 0.01) were positively related to basal LH level around the LH surge. From these data, we conclude that insulin and IGF-1 levels during the WOI are related to LH secretion and follicle development. Not only the absolute level of insulin seems important, but also the pattern within a day in which insulin is secreted seems to affect LH secretion and development of pre-ovulatory follicles.     

Pregnancy diagnosis in swine: a comparison of the accuracies of mechanical and endocrine tests with return to estrus

The relative accuracies of various commercially available detection procedures in the evaluation of pregnancy status were evaluated in 51 sows of mixed parity. Sows were mated 1 to 3 times during estrus to one or more boars. A blood sample was obtained from each sow between 19 and 23 days after estrus (first day of estrus = day 1) and again between 26 and 30 days and was analyzed by radioimmunoassay for content of progesterone and estrone sulfate, respectively. Sows were considered pregnant if progesterone concentrations were greater than 5 ng/ml and if estrone sulfate concentrations were greater than 0.5 ng/ml. At daily intervals, sows were exposed to mature, sexually aggressive boars and observed for signs of estrus. Between 31 and 35 days of gestation, sows were evaluated for pregnancy by use of the following mechanical devices: a Doppler ultrasound pregnancy detector fitted with an abdominal probe, the Doppler detector with a rectal probe, an amplitude-depth ultrasound pregnancy detector (diode ruler), and another amplitude-depth ultrasound detector from a different manufacturer (oscilloscope). Relative to the proportion of sows that farrowed, the overall accuracies of the techniques were returns to estrus, 98%; estrone sulfate, 92%; progesterone, 92%; Doppler with rectal probe, 86%; Doppler with abdominal probe, 86%; diode ruler amplitude-depth ultrasound, 73%; and oscilloscope amplitude-depth ultrasound, 86%. Estrus detection resulted in the lowest prevalence of sows that were predicted to farrow, but did not subsequently farrow (false-positive diagnoses) and the lowest prevalence of sows that were not predicted to farrow, but subsequently did farrow (false-negative diagnoses).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of pre‐weaning dietary substitutions on plasma insulin and glucose profiles in primiparous sows

The objective of this study was to investigate the effects of substituting 1 kg of a standard lactation diet with 1 kg of a sugar‐rich (15.75 DE MJ/kg) or fat‐rich (23.85 DE MJ/kg) diet during late lactation on blood glucose and insulin changes in primiparous sows. During a 4‐week lactation period, 21 primiparous sows were fed to appetite with a standard lactation diet (14.10 DE MJ/kg). At 9 days before weaning, sows were assigned to a control (C, n = 7), fat (F, n = 6) or sugar (S, n = 8) treatment. During the treatment period (from 8 days before weaning until weaning), 1 kg of the lactation diet was substituted with 1 kg of a sugar‐rich or fat‐rich diet for S and F sows. At 3 days before weaning, serial blood samples were collected for a total of 228 min around feeding to establish pre‐ and postprandial plasma glucose and insulin concentrations. Preprandial plasma glucose and insulin concentrations did not differ between treatments (p > 0.05); however, mean plasma glucose and insulin concentrations were higher for S compared to F (p < 0.05) and intermediate for the C sows. Postprandial plasma concentrations of glucose and insulin were higher for the S sows than for C and F sows (p < 0.05). Sow body weight loss during late lactation did not differ between treatments (p > 0.05). The results from our study suggest that a sugar‐enriched diet during the last week of lactation elevates circulating glucose and insulin concentrations and may potentially improve post‐weaning fertility in primiparous sows.     

Influence of Postpartum Cloprostenol Treatment in Sows on Subsequent Reproductive Performance under Field Conditions

During the previous decade several studies focused on postpartum treatment with prostaglandin for improvement of reproductive performance in sows. The aim of the study was to investigate the effect of administration of a prostaglandin F_{2 α} (PGF_{2 α} ) analogue in sows within 24–48 h after farrowing on sow and litter performance. In five commercial farms, the sows were randomly assigned to either treatment A (2 ml cloprostenol, Planate^IM) or treatment B (2 ml physiological saline solution, i.m.). Fifteen per cent of all sows were at random selected for progesterone analysis. Litter performance was assessed by measuring pre-weaning mortality and average daily weight gain (ADG). Sow performance was assessed by measuring weaning-to-oestrus interval (WOI), the percentage of sows returning to oestrus and litter size during subsequent farrowing. Administration of a PGF_{2 α} analogue within 24–48 h postpartum had no effect on the rate of progesterone decline measured over 24 h compared with that of the controls. Litter performance and WOI were not affected by treatment. The subsequent litter size in sows of parity seven and more showed a significant difference of 1.98 piglets (p < 0.01) between both groups, to the benefit of the cloprostenol group. In conclusion, administration of a synthetic PGF_{2 α} analogue, cloprostenol, within 24–48 h after farrowing improved litter size at next farrowing in older (≥7 parity) sows.     

Alteration of reproductive hormone levels in pregnant sows induced by repeated ACTH application and its possible influence on pre- and post-natal hormone secretion of piglets

Prenatal stress has been seen as a reason for reproductive failures in pig offspring mostly originated or mediated by changed maternal functions. Experiments were conducted in pregnant gilts (n=32) to characterize effects of elevated maternal glucocorticoids on the secretion of reproductive hormones (LH, progesterone) during the 1st (EXP 1), 2nd (EXP 2) and 3rd (EXP 3) trimester of pregnancy (TP). Transiently elevated cortisol release was repeatedly achieved by application of 100 IU adenocorticotropic hormone (ACTH) (Synacthen Depot) six times every second day beginning either on day 28 (EXP 1), day 49 (EXP 2) or day 75 of pregnancy (EXP 3). Glucocorticoid concentrations were examined in umbilical blood vessels of fetuses which mothers were subjected to ACTH at 2nd and 3rd TP (EXP 4). Furthermore, the pituitary function of newborn piglets of EXP 2 was checked by a LH-RH challenge test. In sows, LH concentrations were at low basal level (0.1-0.2 ng/ml) but with pulsatory release pattern during each TP. The number of LH pulses/6 h (LSM +/- SE) of saline treated Controls increased with ongoing pregnancy and decreased to the 3rd TP (1.3 +/- 0.2 in EXP 1 vs. 2.0 +/- 0.1 in EXP 2 vs. 1.4 +/- 0.1 in EXP 3, p<0.05). After ACTH treatment the number of LH pulses left unchanged in Experiments 1 and 2 (1.3 +/- 0.2 and 1.5 +/- 0.1) and decreased in EXP 3 (0.8 +/- 0.2, p<0.05). Differences (p<0.05) were obtained comparing the LH pulse number of ACTH and saline treated sows at the 2nd and 3rd TP. Moreover, areas under the curve (AUC) of each LH pulse and of LH over baseline were significantly reduced by treatment. Levels of progesterone increased (p<0.05) for 150 to 170 min after each ACTH application both in EXP 1 and EXP 2, but not in EXP 3. The mean progesterone concentration was different between trimesters, and ACTH and Controls (1st TP: 30.0 +/- 0.9 and 24.4 +/- 0.7 ng/ml; 2nd TP: 35.5 +/- 0.9 and 29.1 +/- 1.0 ng/ml; 3rd TP: 13.6 +/- 0.2 and 13.1 +/- 0.1 ng/ml; p<0.05). In fetuses (n=87) recovered 3 h after ACTH or saline (EXP 4), the plasma cortisol concentrations were significantly increased in umbilical vein (93.7 +/- 5.5 vs. 47.0 +/- 5.3 nmol/l) and artery (95.7 +/- 5.4 vs. 66.4 +/- 5.4 nmol/l), and in periphery (46.8 +/- 5.3 vs. 27.1 +/- 5.3 nmol/l) compared to controls. Plasma ACTH concentrations, however, did not differ in fetuses of both treatment groups. Postnatal LH-RH challenge tests (1st and 28th day post partum) induced LH surges in female piglets (n=67) both of ACTH and saline treated sows, but did not differ between groups (1st day: 7.2 +/- 0.8 vs. 8.1 +/- 0.7 ng/ml; 28th day: 10.5 +/- 1.7 vs. 13.6 +/- 2.2 ng/ml). However, basal LH of piglets whose mothers were submitted to ACTH during 2nd TP was lower on 1st day (1.7 +/- 0.2 vs. 2.3 +/- 0.2 ng/ml, p<0.05) but not on 28th day (1.0 +/- 0.2 vs. 1.1 +/- 0.2 ng/ml). However in both groups, the basal LH was always higher on 1st as on 28th day (p<0.05). Thus, chronic intermittent ACTH administration is able to influence the release pattern of maternal reproductive hormones. However, these findings demonstrate that these effects are dependent on the stage of pregnancy. Furthermore, it was shown that maternal cortisol can cross the placenta during gestation and thus may affect maternal-fetal interactions and, as a result, reproductive function of offspring.     

Prolactin and progesterone concentrations during early pregnancy and relationship to pregnancy loss prior to day 45

Eleven multiparous Quarter Horse and Thoroughbred mares were used to determine the plasma concentrations of progesterone and prolactin during early pregnancy and to examine the relationship of plasma progesterone and prolactin to pregnancy loss prior to d 45 of gestation. Plasma samples were collected at two day intervals beginning on d 14 of pregnancy (d 0 = ovulation) and countinued to d 80. Ovulation and pregnancy status were determined by ultrasonography. Four mares experienced pregnancy loss between d 28 and 44 and plasma samples were collected for 10 days beyond the detected loss. Seven mares had successful pregnancies (Term group).Plasma progesterone concentrations peaked by d 28 in the Term group, with individual peak values ranging from 14.9 to 31.9 ng/ml. Values then declined until d 36, followed by a rise until d 80. Prior to d 45 of gestation 5 of the 7 mares had a peak in excess of 15 ng/ml and 3 of these had brief periods, ranging fron 1 to 8 days when progesterone dropped to less than 2 ng/ml. The other 2 mares had peak plasma progesterone concentrations of less than 7 ng/ml, but maintained concentrations in excess of 2 ng/ml during this period.Within the mares experiencing pregnancy loss, 2 mares had a decline in plasma progesterone concentrations prior to pregnancy loss, while the other 2 had typical progesterone patterns beyond the detected loss. Differences in individual patterns of plasma progesterone concentration were observed in both groups (P<.01).Plasma prolactin concentrations ranged from less than .32 to 4.58 ng/ml in the Term group and from .31 to 1.9 ng/ml in the mares experiencing pregnancy loss. Differences in the individual patterns of prolactin secretion were observed in both groups (P<.01).A correlation between progesterone and prolactin was observed in the Term group between day 14 and 37 (P<.01, r²=.88).     

Effects of postweaning dietary energy source on reproductive traits in primiparous sows

An experiment was conducted to study the effects of major dietary energy source fed from weaning to ovulation or from ovulation to d 35 of pregnancy on reproductive traits in primiparous sows. Dietary energy sources were used to manipulate the plasma insulin concentration. One hundred thirteen sows were used in a split-plot design. From weaning to ovulation sows were fed at two times maintenance either a diet with tallow (Fat) or maize starch plus dextrose (Starch) as the major energy source. From ovulation onward, sows within each dietary group were alternately reassigned to either the Fat or the Starch diet and were fed at 1.25 times maintenance. Estrus detection was performed three times a day from d 3 to 9 after weaning and sows were inseminated each day of standing estrus. On d 35 of pregnancy, the sows were slaughtered and their reproductive tracts were removed. Plasma insulin concentration was higher in sows fed the Starch-rich diet than in sows fed the Fat-rich diet on d 4 after weaning (1.30 vs 0.97 ng/mL, P = 0.08) and on d 32 of pregnancy (1.20 vs 0.51 ng/mL, P < 0.001). Plasma glucose and IGF-I concentration on d 4 after weaning and d 32 of pregnancy did not differ between sows on the two dietary energy sources. The percentage of sows exhibiting estrus within 9 d after weaning was 52 and 67% for the Fat and Starch diet before ovulation, respectively (P = 0.11), whereas the weaning-to-estrus interval was 134 vs 123 h, respectively (P = 0.12). Survival analysis showed that sows fed the Fat-rich diet had a 1.6 times higher risk to remain anestrous until d 9 after weaning than sows fed the Starch-rich diet (P = 0.04). No effect of dietary energy source, either before or after ovulation, on uterine, placental, or embryonal development on d 35 of pregnancy was found. It can be concluded that the dietary energy source provided after weaning can affect the risk of sows to remain anestrous but does not affect uterine, placental, or embryonic traits.     

Cystic Degeneration in Porcine Ovaries - Second Communication: Concentrations of Progesterone, Estradiol-17β, and Testosterone in Cystic Fluid and Plasma; Interpretation of the Results

Contents: The content of progesterone, estradiol-17β, and testosterone of plasma and cystic fluid was determined in 79 sows with ovarian cysts. The average progesterone concentration of sows with dark corpora lutea (CL) was higher than of sows with pale or absent CL (39.4 vs. 8.7 vs. 8.0 ng/ml plasma; p < 0.001; and 7512 vs. 3644 vs. 2723 ng/ml cystic fluid, respectively; p < 0.001). The cystic fluid of animals with oligocystic ovaries (10 cystslanimal) had a significant higher progesterone concentration in comparison to potycystic animals (7200 vs. 3682 ng/ml; p < 0.001). Testosterone and estradwl-17β levels in plasma and in cystic fluid of polycystic animals were significantly higher in comparison to oligocystic animals (Plasma-Testosterone: p < 0.01; Plasma-Estradwl: p < 0.05; Cyst-Testosterone: p < 0.01; Cyst-Estradiol: p < 0.001). In oligocystic ovaries testosterone in cysts exceeded the estradiol-17β levels, whereas in polycystic ovaries the situation was vice versa (p < 0.001).
It is suggested that cystic ovarian degeneration in the sow is not exclusively a gradually progressing process, rather then a complex syndrome with three components, were characterized by a separate course of development (oligocystic, polycystic. oligo-polycystic syndrome).     

Serum Profiles of Pregnancy-Associated Glycoprotein, Oestrone Sulphate and Progesterone During Gestation and Some Factors Influencing the Profiles in Ethiopian Borana and Crossbred Cattle

This study presents serum concentrations of pregnancy‐associated glycoprotein (PAG), oestrone sulphate (E1‐S) and progesterone (P4), and the effects of some dam and foetus‐related factors on these profiles during gestation in Borana and crossbred cattle. The PAG concentrations at 4th week post‐conception ranged from 1.5–5.5 and 2.1–4.7 ng/ml in Borana (n = 6) and crossbred (n = 8) cattle, respectively. The mean PAG concentrations increased progressively from 4th to 33rd week of gestation (from 3.3–173 ng/ml for Borana and 4.2–240 ng/ml for crossbred cattle) and reached peak around calving. Breed, parity status, dam body weight, foetal sex and foetal birth weight significantly influenced the PAG concentrations. After delivery, the PAG concentrations declined steadily to 5.7 ng/ml in Borana (n = 7) and 3.9 ng/ml in crossbred (n = 6) cattle 10 weeks post‐partum. The serum E1‐S concentrations at 17th week of pregnancy ranged from 0.3–2.6 and 0.9–5.7 ng/ml in Borana (n = 8) and crossbred (n = 9) cattle, respectively. The mean E1‐S concentrations increased progressively from 17th to 33rd week of gestation (from 1.1–4.6 ng/ml for Borana and 2.7–10.8 ng/ml for crossbred). Breed, parity status, dam body weight and foetal sex significantly influenced E1‐S concentrations. The P4 concentrations at 4th week of pregnancy ranged from 3.2–5.1 and 1.7–8.9 ng/ml in Borana (n = 6) and crossbred (n = 8) cattle, respectively. The P4 level remained elevated throughout pregnancy. This study indicated that the serum PAG and P4 concentrations at 4th and E1‐S approximately 17th week of pregnancy were above the cut‐off value for pregnancy test and the hormonal profiles observed were comparable to the previous reports. Furthermore, the PAG and E1‐S profiles were considerably influenced by factors such as breed, weight and parity status of the dam, and foetal sex and foetal birth weight (only PAG).     

High Periconceptional Protein Intake Modifies Uterine and Embryonic Relationships Increasing Early Pregnancy Losses and Embryo Growth Retardation in Sheep

The effects of supplemented protein level (PL) during the periconceptional period and their interaction with body condition were evaluated in sheep. Multiparous Rambouillet ewes (n = 12) received two PL of rumen undegradable protein (UIP) during a 30‐day pre‐mating and 15‐day post‐mating period: low [LPL, 24% crude protein (CP), 14 g UIP and 36 g/CP animal/day] and high [HPL, 44% CP, 30 g UIP and 50 g/CP animal/day]. While ovulation rate (OR) did not differ between treatments (1.6 ± 0.5, mean ± SEM), a lower fertility rate, a decreased embryo number and a reduced uterine pH (UpH) was observed in the HPL group (p < 0.05), irrespective of BC. Luteal tissue weight, volume and progesterone secretion did not differ among treatments. Sheep with lower UpH also had lower conceptus weight (Cwt; p < 0.05, r = 0.65) and conceptuses with lower mass tended to secrete less INF‐τ and IGF‐1, and the correspondent endometrial explants had a higher basal PGF_2α release. Current study indicates that high protein diets during the periconceptional period in sheep modify uterine and embryonic relationships, increasing early pregnancy losses and inducing embryo growth retardation. Surviving embryos were affected by weight reductions, which could compromise later foetal growth and birth weight. Results evidence the key role of a balanced diet in reproductive success and indicate that the quality and nutrient composition of the maternal diet are essential for an adequate establishment of pregnancy, having paramount effects on the interplay of the embryo and the uterus.     

Dietary energy source at two feeding levels during lactation of primiparous sows: I. Effects on glucose, insulin, and luteinizing hormone and on follicle development, weaning-to-estrus interval, and ovulation rate

Our objective was to study the effects of dietary-induced insulin enhancement during and after lactation on the reproductive performance of primiparous sows. During a 21-d lactation period, 48 sows were allotted to a 2x2 factorial experiment. Treatments were feeding level (high or low; 44 MJ or 33 MJ NE/d) and dietary energy source (fat or starch). After weaning, all sows received the same amount of feed (31 MJ NE/d from weaning to estrus and 17.5 MJ NE/d from breeding until slaughter) of the same energy source as fed during lactation. On d 7, 14, and 21 of lactation and d 22 (weaning), blood samples were taken every 12 min for 12 h and analyzed for plasma glucose, insulin, and LH. Sows were slaughtered on d 35 of the subsequent pregnancy, and ovulation rate was assessed. During lactation, postprandial plasma glucose and insulin concentrations were higher for sows fed the starch diet than for those fed the fat diet (P<.001), whereas feeding level had no effect. Basal and mean LH concentrations were not affected by treatments. The LH pulse frequency on d 7 of lactation was greater for sows fed the starch diet than for those fed the fat diet (.52 vs .17 pulses/12 h; P = .03). The high compared with the low feeding level resulted in a greater LH pulse frequency on d 21 of lactation (.89 vs .47 pulses/12 h; P = .05) and on d 22 (8.63 vs 5.77 pulses/12 h; P = .02), in a higher percentage of sows that exhibited estrus within 10 d after weaning (96 vs. 63%; P = .01), and a tendency for a higher ovulation rate (18.0 vs. 16.2; P = .09). Plasma glucose and insulin concentrations were not related to any of the LH traits. The LH pulse frequency after weaning was related to the weaning-to-estrus interval (WEI) and was best explained by a linear-plateau model. In sows fed the low feeding level, follicle size after weaning was correlated with LH pulse frequency after weaning and with the WEI, whereas in sows fed the high feeding level these correlations were not significant. Our results indicate that an improved dietary-induced insulin status during and after lactation does not overcome the inhibitory effects of lactation on subsequent reproduction at any of the feeding levels.     

Porcine Luteal Function in Relation to IGF-1 Levels Following Ovulation During Lactation or After Weaning

Contents This study presents relationships between peripheral progesterone and Insulin-like Growth Factor-1 (IGF-1) concentrations during the early luteal phase in sows. Data were derived from three experiments, one with primiparous weaned sows (n = 21) and two with multiparous sows that either ovulated during lactation (n = 23) or after weaning (n = 12). The sows that ovulated during lactation did so due to an intermittent suckling regime (inhibition of suckling for 12 h each day from day 14 of lactation) or due to treatment with PG600. IGF-1 concentrations varied considerably among experiments, and were the lowest in the multiparous sows, regardless of whether they were weaned or lactating: 68 ± 5 and 85 ± 8 ng/ml in the two experiments with multiparous sows vs 188 ± 15 ng/ml in the primiparous sows. Progesterone concentrations were lowest for the lactating sows. Overall, the increase in progesterone during the early luteal phase was strongly correlated with IGF-1 concentrations (r = 0.7). However, the correlation was low in multiparous lactating sows (r = 0.28; p < 0.10) and nonsignificant in multiparous weaned sows (r = 0). The weaned multiparous sows had IGF-1 levels comparable to lactating multiparous sows, but higher progesterone levels. In conclusion, these data show a positive relationship between peripheral IGF-1 and progesterone concentrations in vivo during the early luteal phase. In lactating sows, IGF-1 concentrations are probably a limiting factor for progesterone secretion, although other factors may be involved.     

Housing During Early Pregnancy Affects Fertility and Behaviour of Sows

From 1.1.2013 EU legislation will permit stall‐housing of dry sows for only 4 weeks post‐service. Stalls are associated with compromised animal welfare, but group housing comes with risks from social confrontations. Studies on housing effects on fertility have produced contradictory results as systems are inconsistently defined. Effects of housing on pregnancy rate 28 days post‐service (P28), early disruption of pregnancy (EDP) and behaviour were investigated in 12 replicates of 40 sows. Half of the animals were stalled (treatment S, mean parity 2.4) and half group‐housed adjacent on 5.1 m² deep litter per sow (treatment G, mean parity 2.3). Pregnancy was detected using real‐time ultrasound. An EDP‐diagnosis required a drop of salivary progesterone concentration from >15.9 to <15.9 mmol/l in a series of samples taken on days 17, 20, 24 and 27 post‐service. Behaviour was scan sampled on day 27 for 120 min with 10‐min intervals. Data was analysed using mixed regression models in MLwiN. Treatment S increased the odds for P28 with 2.3 and the pregnancy rate of a treatment group with 0.1 compared with G. G increased the odds for EDP with 4.6. Treatment did not affect total exploratory or total passive behaviour. S sows explored floor and fixtures (not bedding) more and performed more passive sitting than G sows. Social stress may have caused the impaired reproductive performance in G sows. S sows showed behavioural signs of decreased welfare, but no corresponding reproductive effects. An interdisciplinary approach is needed when evaluating the appropriateness of housing systems.     

Lactation Weight Loss in Primiparous Sows: Consequences for Embryo Survival and Progesterone and Relations with Metabolic Profiles

Our objective was to study reproductive consequences of lactation bodyweight loss occurring in primiparous sows with mild feed restriction and to relate these lactation weight losses and its consequences to metabolic profiles during lactation and subsequent early gestation. After weaning, 47 first‐litter sows were retrospectively assigned to a high– (HWL, >13.8%, n = 24) or low (LWL, ≤13.8%, n = 23)–weight loss group. Thirty‐six animals received an indwelling jugular vein catheter to determine lactational and gestational profiles of insulin‐like growth factor‐1 (IGF‐1), non‐esterified fatty acids (NEFA) and urea and gestational profiles of progesterone. At day 35 after insemination, sows were euthanized and their reproductive tract collected. Pregnancy rate was 75% (18/24) for HWL and 96% (22/23) for LWL sows. High–weight loss sows had a lower number of implantation sites (17.2 ± 0.8 vs 19.5 ± 0.7, respectively, p = 0.03) and a lower embryonic survival (65.6 ± 3.4 vs 77.4 ± 2.9%, p = 0.02), resulting in fewer vital embryos (14.9 ± 0.9 vs 16.8 ± 0.7, p = 0.07) than LWL sows. Progesterone peak values were reached later in HWL than in LWL sows (day 13.4 ± 0.5 vs 12.0 ± 0.5, respectively, p = 0.05). Gestational concentrations of IGF‐1, NEFA and urea were almost identical for HWL and LWL sows, whilst numerical differences were seen during lactation. The current study shows negative consequences of lactational weight loss in mildly feed‐restricted primiparous sows for embryonic survival and shows that these consequences seem only mildly related with metabolic alterations during lactation and not with metabolic alterations during subsequent gestation.     

Production of calcium maintenance factor Stanniocalcin-1 (STC1) by the equine endometrium during the early pregnant period

A factor responsible for progression to pregnancy establishment in the mare has not been definitively characterized. To identify factors possibly involved in the establishment of equine pregnancy, the endometrium was collected from day 13 (day 0=day of ovulation) cyclic and day 13, 19 and 25 pregnant animals. From initial subtractive hybridization studies, a calcium regulating factor, Stanniocalcin-1 (STC1) mRNA, was found as a candidate molecule expressed uniquely in the pregnant endometrium. Endometrial expression of STC1 mRNA was noted on day 19 and was markedly increased in the day 25 gravid endometrium. STC1 protein was found in the extracts of day 25 gravid endometrium and immunochemically localized in the uterine glands. In addition, STC1 protein was detected in uterine flushing media collected from day 25 pregnant mares. High concentrations of estradiol-17 β (E(2)) were detected in day 25 conceptuses. E(2) levels were much higher in the gravid endometrium than in other regions, whereas progesterone levels did not differ among the samples from different endometrial regions. Expression of STC1 mRNA, however, was not significantly upregulated in cultured endometrial explants treated with various concentrations of E(2) (0.01-100 ng/ml) with or without 10 ng/ml progesterone. These results indicate that an increase in STC1 expression appears to coincide with capsule disappearance in the conceptus, and suggest that STC1 from the uterine glands likely plays a role in conceptus development during the pregnancy establishment period in the mare.     

Plasma progesterone levels in sows with induced cystic ovarian follicles.

Large multiple cystic ovarian follicles were induced in three sows and small multiple cystic ovarian follicles were induced in three other sows by injections of adrenocorticotrophic hormone (ACTH) during the follicular phase of the oestrous cycle. Plasma progesterone levels in sows with large cysts were relatively high, while those of sows with small cystic follicles were low. Removal of the ovaries with large cysts from one sow resulted in a precipitous drop in progesterone levels indicating that the large cysts were primarily the source of progesterone. The method by which ACTH may induced cystic ovaries was also investigated. Plasma progesterone levels in two ovariectomised sows during ACTH treatment fluctuated markedly during a 24 h period achieving peak values of 4 or 5 ng/ml. The results suggest that progesterone of adrenal cortical origin may be a factor in the development of the cystic ovarian condition.     

A role for the adrenal cortex in the onset of cystic ovarian follicles in the sow.

The corticotrophin (ACTH)-adrenal cortical axis has previously been implicated in the onset of cystic ovaries in the sow. In view of the role of the ACTH-adrenal cortical axis in stress, two sows were subjected to an elevated environmental temperature of 32 degrees C for three hours daily during the follicular phase of the estrous cycle. Plasma concentrations of glucocorticosteroids and progesterone fluctuated markedly in one sow that developed cystic ovaries. Concentrations of these hormones did not vary greatly in the other sow that did not develop cystic follicles. Exposure to an environmental temperature of 32 degrees C for three hours or injection of 1 IU/kg bodyweight of ACTH for each of two ovariectomized sows resulted in an elevation in progesterone values to 5-7 ng/ml plasma from basal levels of 1-2 ng/ml and a rise in total glucocorticosteroids from basal levels of 1 or 2 microgram/100 ml plasma to 4-10 microgram/100 ml. Injection of 2 mg/kg bodyweight of progesterone and 4 mg/kg bodyweight of cortisol into the ovariectomized sows was found to approximate these elevations in plasma steroid values. When either progesterone or cortisol was injected daily during the follicular phase into two intact sows in two successive experiments at these dosage levels, similarly elevated plasma steroid concentrations were seen and cystic ovarian follicles resulted. The results suggest that glucocorticosteroids and progesterone of adrenal origin may be involved in the onset of cystic ovaries in the sow.     

Follicular and oocyte development in gilts of different age

The aim of the present study was to estimate follicular and oocyte development of the same gilts in three phases of their reproductive life--prepuberal gilt (6 months old), cycling gilt (9.5 months old) and primiparous sow. Follicular development was induced by injections of 1000 IU PMSG followed by 500 IU hCG 72 h later. Cumulus-oocyte-complexes (COCs) were recovered from preovulatory follicles of the left ovary, and follicular fluid (FF) from the right ovary always 34 h after hCG by endoscopy. Altogether, 19 gilts were used in the prepuberal (P) and cycling (C) trials and 12 of them in the primiparous trial (S). Altogether 168, 190 and 82 follicles were aspirated from the left ovary and 106, 125 and 42 COCs recovered (recovery rate 60.5 +/- 26.9, 62.7 +/- 20.9 and 52.9 +/- 21.8%). The average number of follicles was higher in C compared to P (19.7 +/- 6.8 vs. 15.7 +/- 6.8, p = 0.06) and to S (14.2 +/- 4.0, p < 0.05), respectively. More uniform expanded COCs were aspirated from prepuberal and cycling gilts as compared to sows (89.7 and 78.4% vs. 46.3%, p < 0.05). Furthermore, the meiotic configuration in oocytes differed (p < 0.05) between these groups (55.5 and 61.7% vs. 0% Telo 1/Meta 2). Concentrations of progesterone in FF decreased (p < 0.05) from 590.0 +/- 333.6 (P) to 249.1 +/- 72.6 (C) and 161.4 +/- 75.2 ng/ml (S). FF concentrations of oestradiol-17 beta were different between gilts and sows (9.3 +/- 2.9, 21.9 +/- 10.6 and 94.0 +/- 15.9 pg/ml, p < 0.05). The progesterone/oestradiol ratio was 72.1, 15.2 and 4.7. Results indicate a different follicular and oocyte development during the investigated lifetime periods. Cycling gilts should preferably be used in IVF and breeding programs. The lower reproductive potential of primiparous sows is taken into consideration at breeding. Prediction of lifetime performance based on individual ovarian reaction of prepuberal gilts is unsuitable.     

Altrenogest and fat for summer breeding of primiparous sows

Delaying the onset of estrus after weaning and adding fat to the postweaning diet were studied for their effects on estrus and fertility in 232 crossbred primiparous sows on a commercial swine farm. Sows were assigned randomly to the following treatments after weaning in June, July, August, or September, 1983: 1) altrenogest (20 mg/d) was fed for 7 d after weaning (n = 76), 2) altrenogest was fed for 7 d plus .53 kg dried animal and vegetable fat product (.45 kg actual fat/d) for 14 d after weaning (n = 78), or 3) no treatment (controls, n = 78). While a similar proportion of sows came into heat after weaning (lactation length = 4 wk), sows fed altrenogest (14.4 +/- .2 d) returned to estrus about 9 d later (P less than .01) than controls (5.6 +/- .2 d). Serum progesterone concentration was assayed in blood samples collected from a subgroup (74%) of the cows not observed in estrus by 3 wk after weaning to determine possible causes of anestrus. If serum progesterone (greater than 5 ng/ml) was elevated, we assumed that sows had ovulated without expressing estrus (behavioral anestrus) or ovulated with undetected estrus (less overt estrus or error in estrous detection), whereas low progesterone (less than or equal to 5 ng/ml) indicated that sows were anovulatory. About 53% of the sows not observed in estrus across all treatments had luteal function, probably resulting from post-weaning ovulation. Incidence of anovulation without estrus was 47%. Farrowing rate was higher (P less than .05) for sows fed only altrenogest (64%) compared with controls (46%), but similar to fat supplemented, altrenogest-treated sows (52%).(ABSTRACT TRUNCATED AT 250 WORDS)     

Field experiences with early pregnancy diagnosis by progesterone-based ELISA in sows

In four Kenyan pig breeding units the pregnancy diagnosis of sows has been carried out in two groups: Group 1 (n = 1911): the sows were transrectaly pregnancy tested between Days 17-22 post-mating by ultrasound. Sows testing non-pregnant immediately received one dose of 400 IU pregnant mare serum gonadotropin (PMSG) (equine chorion gonadotropin, eCG) and 200 IU human chorion gonadotropin (hCG). On showing signs of oestrous, the animals were subsequently artificially inseminated (AI). Group 2 (n = 1923): sows were pregnancy tested by serum progesterone (P4)-based enzyme-linked immunosorbent assay (ELISA) on Day 17 post-breeding. P4 concentrations were categorized as positive (> 5 ng/ml) or negative (< 5 ng/ml). Sows testing nonpregnant immediately received one dose of 400 IU PMSG and 200 IU hCG by injection, and were subsequently artificially inseminated. The following parameters were evaluated: sows diagnosed non-pregnant, days from first post-weaning insemination until the sows were inseminated at their first return to oestrus; farrowing rate and total piglets born and number of live-born piglets in litters. The percentage of sows diagnosed non-pregnant in the two groups, as well as the totals of born piglets and of live-born piglets in litters did not differ significantly between the two groups. The number of days from the first post-weaning mating until the sows were artificially inseminated at their first return to oestrus and the administration of eCG and hCG was shorter (P < 0.01) and farrowing rate was higher (P< 0.01) in the ELISA-tested sows.