Late Pregnant Sows Research Articles

Effects of Dietary Lonicera flos and Sucutellaria baicalensis Mixed Extracts Supplementation on Reproductive Performance, Umbilical Cord Blood Parameters, Colostrum Ingredients and Immunoglobulin Contents of Late-Pregnant Sows.

The present study aimed to determine the effects of dietary Lonicera flos and Sucutellaria baicalensis mixed extract (LSE) supplementation during the late-pregnancy period on the reproductive performance, umbilical cord blood hematological parameters, umbilical cord serum biochemical parameters, immune indices, hormone levels, colostrum ingredients, and immunoglobulin contents of sows. A total of 40 hybrid pregnant sows were randomly assigned to the control group (CON; sows fed a basal diet) and LSE group (LSE; sows fed a basal diet supplemented with 500 g/t PE). The results indicated that dietary LSE supplementation significantly increased (p < 0.05) the number of alive and healthy piglets and the litter weight at birth, and significantly increased (p < 0.05) the platelet counts in umbilical cord blood. Dietary LSE supplementation significantly increased (p < 0.05) the levels of prolactin (PRL) and growth hormone (GH), and the content of interleukin 2 (IL-2) in umbilical cord serum. Moreover, immunoglobulin A (IgA) and immunoglobulin M (IgM) in the colostrum were increased with PE supplementation (p < 0.05). In conclusion, dietary LSE supplementation in late-pregnancy sows could improve reproductive performance and colostrum quality, and could also regulate the levels of reproductive hormone in umbilical cord serum.

Improvement of insulin sensitivity by dietary fiber consumption during late pregnant sows is associated with gut microbiota regulation of tryptophan metabolism

BackgroundDietary fiber (DF) consumption was reported to improve insulin sensitivity, change the tryptophan metabolism, and alter the gut microbiota. Herein, this study aimed to investigate the effects of DF consumption on insulin sensitivity, tryptophan metabolism, and gut microbiota composition in sows during late pregnancy, and explore the relationship between tryptophan metabolites and insulin sensitivity regulated by DF supplementation.ResultsTwelve sows were randomly assigned to two dietary treatment groups (six/group): the low-fiber (LF) group, which was fed a basal diet, and the high-fiber (HF) group, which was fed the basal diet supplemented with 22.60 g/kg inulin and 181.60 g/kg cellulose. During late pregnancy, meal test, glucose tolerance test, and insulin challenge test were used to investigate the insulin sensitivity of sows, using the percutaneous brachiocephalic vein catheterization technique. High DF consumption resulted in improved insulin sensitivity, especially during the second and third trimesters, and promoted serotonin production from tryptophan. Additionally, plasma serotonin concentration was positively correlated with the insulin sensitivity index during late pregnancy. Moreover, DF consumption elevated fecal short-chain fatty acid (SCFA) concentrations, altered fecal microbial diversity, and increased the abundances of Rikenellaceae_RC9_gut_group, Alloprevotella, Parabacteroides, Roseburia, and Sphaerochaeta, which were positively correlated to plasma serotonin concentration.ConclusionsDF consumption improved insulin sensitivity during late pregnancy in sows, which improved microbial diversity in fecal samples and increased fecal SCFA concentrations, resulting in a positive correlation with plasma serotonin level.

Probiotics alleviate constipation and inflammation in late gestating and lactating sows

Constipation and systemic inflammation are common in late pregnant and lactating sows, which cause health problems like uteritis, mastitis, dystocia, or even stillbirth, further influencing piglets’ survival and growth. Probiotic supplementation can improve such issues, but the beneficial mechanism of relieving constipation and enhancing gut motility remains underexplored. This study aimed to investigate the effects and mechanism of probiotic supplementation in drinking water to late pregnant sows on constipation, inflammation, and piglets’ growth performance. Seventy-four sows were randomly allocated to probiotic (n = 36) and control (n = 38) groups. Probiotic treatment significantly relieved sow constipation, enhanced serum IL-4 and IL-10 levels while reducing serum IL-1β, IL-12p40, and TNF-α levels, and increased piglet daily gain and weaning weight. Furthermore, probiotic administration reshaped the sow gut bacteriome and phageome structure/diversity, accompanied by increases in some potentially beneficial bacteria. At 113 days of gestation, the probiotic group was enriched in several gut microbial bioactive metabolites, multiple carbohydrate-active enzymes that degrade pectin and starch, fecal butyrate and acetate, and some serum metabolites involved in vitamin and amino acid metabolism. Our integrated correlation network analysis revealed that the alleviation of constipation and inflammation was associated with changes in the sow gut bacteriome, phageome, bioactive metabolic potential, and metabolism.

Targeting gut microbiota-derived butyrate improves hepatic gluconeogenesis through the cAMP-PKA-GCN5 pathway in late pregnant sows.

Short chain fatty acids (SCFAs) produced by gut microbiota affected hepatic glucose metabolism via the gut-liver axis. The present study aimed to investigate the effects of butyrate produced by gut microbiota on hepatic gluconeogenesis in late-pregnancy sows. A total of 240 primiparous sows in late pregnancy were tested for blood glucose using a glucose meter before feeding and grouped according to their blood glucose level as follows: 0-3.0 mmol L-1 (low blood glucose group, LG group) and 3.1-5.0 mmol L-1 (normal blood glucose group, NG group). Colonic SCFAs and microbiota, SCFAs in the portal vein and liver, and acetylation and phosphorylation levels in the liver samples were analyzed. Hepatocytes from pregnant sows were examined for the effect of butyrate on hepatic glucose gluconeogenesis. In vivo experiments showed that the reproductive performance, serum glucose metabolism index, colonic butyrate and butyrate-producing bacteria decreased in the LG group compared with the NG group. Correlation analysis found a positive correlation among colonic butyrate, butyrate-producing bacteria and the serum glucose metabolism index. Moreover, the hepatic cAMP concentration, PKA activity, GCN5 phosphorylation, and the expression of G6P and PEPCK were decreased and PGC1-α acetylation was increased in the LG group compared with the NG group. In vitro, sodium butyrate significantly stimulated the cAMP concentration, PKA activity, GCN5 phosphorylation, and the expression of G6P and PEPCK and inhibited PGC-1α acetylation in the LG group of hepatocytes from late-pregnancy sows. Interestingly, another in vivo experiment showed that dietary 1-kestose, a natural regulator of gut bacteria, significantly increased butyrate and butyrate-producing bacteria, and improved the reproductive performance and serum glucose metabolism index in late-pregnancy sows. Taken together, we found that targeting gut microbiota-derived butyrate could improve hepatic gluconeogenesis through the cAMP-PKA-GCN5 pathway in late-pregnancy sows.

Modulation of Gut Microbiota and Oxidative Status by β-Carotene in Late Pregnant Sows.

Recent evidences suggest that gut microbiota plays an important role in regulating physiological and metabolic activities of pregnant sows, and β-carotene has a potentially positive effect on reproduction, but the impact of β-carotene on gut microbiota in pregnant sows remains unknown. This study aimed to explore the effect and mechanisms of β-carotene on the reproductive performance of sows from the aspect of gut microbiota. A total of 48 hybrid pregnant sows (Landrace × Yorkshire) with similar parity were randomly allocated into three groups (n = 16) and fed with a basal diet or a diet containing 30 or 90 mg/kg of β-carotene from day 90 of gestation until parturition. Dietary supplementation of 30 or 90 mg/kg β-carotene increased the number of live birth to 11.82 ± 1.54 and 12.29 ± 2.09, respectively, while the control group was 11.00 ± 1.41 (P = 0.201). Moreover, β-carotene increased significantly the serum nitric oxide (NO) level and glutathione peroxidase (GSH-Px) activity (P < 0.05). Characterization of fecal microbiota revealed that 90 mg/kg β-carotene increased the diversity of the gut flora (P < 0.05). In particular, β-carotene decreased the relative abundance of Firmicutes including Lachnospiraceae AC2044 group, Lachnospiraceae NK4B4 group and Ruminococcaceae UCG-008, but enriched Proteobacteria including Bilophila and Sutterella, and Actinobacteria including Corynebacterium and Corynebacterium 1 which are related to NO synthesis. These data demonstrated that dietary supplementation of β-carotene may increase antioxidant enzyme activity and NO, an important vasodilator to promote the neonatal blood circulation, through regulating gut microbiota in sows.

Garcinol promotes hepatic gluconeogenesis by inhibiting P300/CBP-associated factor in late-pregnant sows.

Disorder of hepatic glucose metabolism is the characteristic of late-pregnant sows. The purpose of our study was to look into the mechanism of garcinol on the improvement of hepatic gluconeogenic enzyme in late-pregnant sows. Thirty second- and third-parity sows (Duroc × Yorkshire × Landrace, n 10/diet) were fed a basal diet (control) or that diet supplemented with 100 mg/kg (Low Gar) or 500 mg/kg (High Gar) garcinol from day 90 of gestation to the end of farrowing. The livers were processed to measure enzymatic activity. Hepatocytes from pregnant sows were transfected with P300/CBP-associating factor (PCAF) small interfering RNA (siRNA) or treated with garcinol. Dietary garcinol had no effect on average daily feed intake, body weight (BW), backfat and BW gain of late-pregnant sows. Garcinol promoted plasma glucose levels in pregnant sows and newborn piglets. Garcinol up-regulated hepatic gluconeogenic enzyme expression and decreased PCAF activity. Garcinol had no effect on the expression of PPAR-γ co-activator 1α (PGC-1α) and Forkhead box O1 (FOXO1) but significantly increased their activity and decreased their acetylation in late-pregnant sows. Transfection of PCAF siRNA to hepatocytes of pregnant sows increased PGC-1α and FOXO1 activities. Furthermore, in hepatocytes of pregnant sows, garcinol treatment also up-regulated the activities of PGC-1α and FOXO1 and inhibited the acetylation of PGC-1α and FOXO1. Garcinol improves hepatic gluconeogenic enzyme expression in late-pregnant sows, and this may be due to the mechanism of down-regulating the acetylation of PGC-1α and FOXO1 induced by PCAF in isolated hepatocytes.

Efficacy of two adjuvant systems to promote humoral immunity to the pre-proghrelin peptide obestatin in pigs: consequences for the growth of piglets to weaning

The poor antigenicity of peptide antigens demands the selection of effective adjuvants to induce humoral immunity. The peptides obestatin and ghrelin from the pro-hormone pre-proghrelin were initially identified as antagonistic in regulating feeding behaviour, with obestatin being suppressive. The efficacy of two adjuvant systems, DEAE with the oil polysorbate emulsion of BP85:Span80 and the surfactant-oil system Montanide (ISA 50v) were therefore assessed with an obestatin-ovalbumin conjugate injected into late pregnant sows. This enabled the supply of antibodies directed against obestatin to newborn piglets through colostrum with the objective of promoting ghrelin secretion and therefore increasing feeding behaviour. Pregnant Landrace × Large White sows (n = 28) were immunised with 0.5 mg obestatin-ovalbumin in 2 mL DEAE:BP85:Span80 (DEAE; n = 14) or with 2 mL Montanide (ISA 50v: n = 14) as adjuvants at days 91 and 105 of gestation. After farrowing, piglets remained with their mothers during the lactation period and were weighed after weaning at Day 28. Antibody titres (unitless) in colostrum were assessed by ELISA as 5543 ± 2388 and 3139 ± 1151 for the DEAE and Montanide adjuvants respectively. These were associated with total IgG of 67.7 ± 3 and 82.3 ± 4.8 mg/mL respectively (P = 0.018). Piglet plasma titres were 5100 ± 1576 and 5762 ± 1688 for DEAE and Montanide respectively at Day 5 postpartum. These titres were still detectable through to Day 28 (titres of 1213 ± 389 and 665 ± 203 respectively (P = 0.176). However, sow colostral antibody titres were not related to piglet antibody concentrations on D5 (r = –0.225, P = 0.341). Sow plasma antibody titres were not related to titres at Day 28 in piglets across treatments (r = 0.198, P = 0.402). The concentration of ghrelin in colostrum was 672 ± 78 and 666 ± 39 pg/mL for the DEAE and Montanide groups, respectively, leading to piglet plasma concentrations on Day 5 of 1105 ± 164 and 530 ± 84 pg/mL (P = 0.002). Animals grew from birthweights of 1.7 ± 0.1 and 1.8 ± 0.1 (P = 0.993) to 7.7 ± 1.2 and 7.8 ± 1.0 kg (P = 0.295) at weaning, representing growth rates of 200.5 ± 52.9 and 225.5 ± 53.4 g/day (P = 0.181). There was a significant negative correlation between piglet D28 antibody titre and growth rate to weaning with the Montanide adjuvant (r = 0.116, P = 0.035) but not for the DEAE (r = –0.118, P = 0.411). Although both adjuvants were capable of generating high antibody titres, the DEAE dextran was likely to be the most effective adjuvant to induce a humoral immune response to develop further with a commercial vaccine.

Por�wnanie zmian otluszczenia loch w ciazy wysokiej i przy odsadzeniu miotu oraz okreslenie ich zwiazku z wynikami rozrodu i odchowu prosiat

Sixty crossbred sows were investigated for the effect of the level of fat reserves in high pregnancy and pre-weaning changes in lipid reserves on reproductive performance of sows and rearing of piglets. At 104 days of pregnancy and at weaning, sows were analysed for body weight, P2 and P4 backfat thickness and M. Longissimus dorsi (MLD) thickness at P4M (Piglog 105). Sows were grouped according to mean backfat thickness (P2 + P4)/2 at 104 days of pregnancy into primiparous (P2 + P4)/2>18 mm (group I), primiparous (P2 + P4)/2≤18 mm (group II), multiparous (P2 + P4)/2>20 mm (group I) and multiparous (P2 + P4)/2≤20 mm (group II). The body weight of sows from group I was higher than sows from group II at 104 days of pregnancy (P ≤ 0.05) and at weaning (P ≤ 0.01). As assumed in the experiment, fatness in high pregnant sows (points P2 and P4) was significantly higher in group I than in group II (P ≤ 0.01), and the differences between the groups persisted when piglets were weaned (P ≤ 0.01). At weaning, sows from group II had a significantly greater P4M thickness compared to sows from group I. The differences in backfat thickness in late-pregnant sows in groups I and II and in the loss of fat reserves during a 21-day lactation had no effect on reproduction results and rearing of piglets. Sows lost body weight to a small extent and fat reserves to a moderate degree; the changes were greater in primiparous than multiparous sows, regardless of the group (I or II).

Effects of dose and route of administration of genistein on isoflavone concentrations in post-weaned and gestating sows

Phytoestrogens could be a useful tool in swine husbandry practices because of their structural and functional similarities to estradiol. The goal of this study was to compare various routes and doses of administration of the phytoestrogen genistein in sows of two different physiological statuses. Circulating concentrations of isoflavones, estradiol and IGF-I were determined. In experiment 1, 65 sows were equally divided into the five following groups, between days 3 and 5 of the first or second estrous cycle post weaning: (1) controls (CTL); (2) 1 g of genistein fed daily (OR1); (3) 2 g of genistein fed daily (OR2); (4) two daily i.m. injections of 200 mg of genistein (IM400); and (5) two daily i.m. injections of 400 mg of genistein (IM800). Treatments were carried out for 10 days. In experiment 2, 10 sows were equally divided into two groups on day 90 of gestation, namely, controls (CTL) or 2 g of genistein fed daily for 10 days (OR2). In both trials, jugular blood samples were collected on days 1 (before treatment), 5 and 10 at 0730 h. In experiment 1, a blood sample was also collected at 1730 h on day 10 for CTL, IM400 and IM800 sows. In experiment 1, circulating concentrations of genistein on days 5 and 10 were greater in OR2, IM400 and IM800 than in CTL and OR1 group sows (P < 0.01). Daily dietary supplementation with 2 g of genistein resulted in blood concentrations that were similar to those in animals given daily two i.m. injections of 200 mg. Values of all isoflavones, except equol, which was not detectable, were greater in PM than in AM on day 10 (P < 0.01). In experiment 2, genistein concentrations were greater in OR2 compared with CTL on days 5 and 10 (P ⩽ 0.05). There was no difference in the genistein response to OR2 because of physiological status (i.e. weaned v. gestating, P > 0.1). Estradiol and IGF-I concentrations were not altered by any of the treatments (P > 0.1). Providing genistein either per os or via i.m. injections increased circulating concentrations of genistein in female swine within 5 days of the onset of treatment. The genistein response to i.m. injections of genistein was similar in weaned and late-pregnant sows, even though endogenous concentrations of estradiol differed. This response was specific in that estradiol, IGF-I and isoflavones other than genistein were not affected by treatments.

Analysis of the Relationship Between Fatness of Late Pregnant and Lactating Sows and Selected Lipid Parameters of Blood, Colostrum and Milk

Analysis of the Relationship Between Fatness of Late Pregnant and Lactating Sows and Selected Lipid Parameters of Blood, Colostrum and MilkThis study determined the relationships between backfat thickness in sows on day 104 (±2) of pregnancy, changes in fatness between high pregnancy and lactation (day 21), the body weight of late pregnant sows, the level of selected lipid parameters in blood serum, and basic components and fatty acid profile of colostrum and milk. Backfat measurements were taken using an ultrasound device at the P1, P2, P3 and P4 sites and loin eye height was measured at the P4M site. In late pregnant sows, fatness measured at P1, P2, P3 and P4 and the mean of measurements taken at P2 and P4 were correlated with HDL (+0.491**, +0.537**, +0.439*, +0.483** and 0.529**, respectively). Measurements taken at P4 and the mean of P2 and P4 were correlated with cholesterol (CHOL, +0.367* and +0.372*, respectively). Correlations were also found between the level of fatness of pregnant sows (P2, P3, P4, (P2 + P4)/2) and the level of HDL at the end of lactation (+0.534**, +0.440*, +0.412* and +0.487**, respectively). The body weight of late pregnant sows was significantly correlated with the energy and fat levels in colostrum (-0.467** and -0.429*, respectively). In addition, it was correlated with the proportion of fatty acids in the profile (C18:2 +0.417*, C18:3 +0.493*). Correlations were observed between P1 backfat thickness and the proportion of colostrum fatty acids (C18:1 +0.483*, CLA +0.475*), and between P2 backfat thickness and the C20:4 content of milk (-0.421*). A relationship between backfat thickness measured at farrowing and the levels of selected fatty acids in colostrum was found for P2 and C18:3 (+0.471*), P3 and C18:0 (-0.608**), C18:2 (+0.463*) and C18:3 (+0.517*), and P4M and C16:1 (-0.513*). The greater the difference in P1 backfat thickness between late pregnancy and weaning, the higher the content of fat (+0.549**), energy (+0.510*), C18:0 (+0.493*) and CLA (+0.488*), and the lower the content of C14:0 (-0.512*) and C16:0 (-0.457*) in milk. The strong correlations of fatness in late pregnant sows and of changes in fatness during late pregnancy and weaning with some blood, colostrum and milk parameters suggest that sows should be evaluated for fatness during their productive life.

The effect of the body condition of late pregnant sows on fat reserves at farrowing and weaning and on litter performance

Abstract. The objective of this study was to determine the effect of the body condition of late pregnant sows on fat reserves at farrowing and weaning, including the scale of the relevant changes in that period, and on the reproductive performance of sows and the results of piglet rearing. The experiment involved 97 hybrid sows (Polish Large White × Polish Landrace [PLW×PL]) divided into two groups, according to backfat thickness: I – (P2+P4)/2&gt;20 mm (10 primiparous, 36 multiparous) and II – (P2+P4)/2≤20 mm (19 primiparous, 32 multiparous). It was carried out between pregnancy day 104 and weaning after 21 days of lactation. During late pregnancy, at weaning and at the end of lactation, the body weight of sows, fatness (points P1, P2, P3, P4) and longissimus muscle depth at point P4M were determined. Feed consumption during lactation, reproductive performance traits and the results of piglet rearing were also analyzed. Higher backfat thickness percentages and body weight noted in group I sows vs. group II sows (P≤0.001) during late pregnancy were maintained at farrowing and weaning. At weaning, the values of longissimus muscle depth were significantly (P≤0.001) higher in group II than in group I. The level of changes in fat reserves differed between late pregnancy and farrowing for P4 (P≤0.01) and (P2+P4)/2 (P≤0.001); fat reserve loss was noted in group I, while an increase in adipose tissue was observed in group II. Body weight losses (%) during late pregnancy and at weaning were non-significant in sows of both groups. Based on feed consumption levels, group I sows were characterized by a lower appetite during lactation than group II sows. A regular trend in feed intake was noted in lactating sows of both groups: feed consumption increased in week 2, compared with week 1, while a decrease was noted in week 3 in comparison with week 2. Significant differences were reported in favour of group I vs. II (P≤0.05) as regards the piglets stillborn, litter weight at weaning, the average piglet weight at weaning and placental weight. Multiparous sows as compared to primiparous sows were characterized by significantly (P≤0.05) larger total number of piglets born and the number of piglets born alive. The difference in the litter weight at birth was found to be highly significant (P≤0.01).

Placental transfer and pharmacokinetics of allopurinol in late pregnant sows and their fetuses

At present no standard pharmacological intervention strategy is available to reduce these adverse effects of birth asphyxia. In the present study we aimed to evaluate placental transfer of allopurinol, an inhibitor of XOR. For this purpose, fetal catheterization of the jugular vein was conducted in five late pregnant sows (one fetus per sow). At 24-48 h after surgery, sows received allopurinol (15 mg/kg body weight; i.v.) and pharmacokinetics of allopurinol and its active metabolite oxypurinol were measured in both late pregnant sows and fetuses. Maternal and fetal blood samples were collected during and after allopurinol administration. Maternal C(max) values averaged 41.90 microg/mL (allopurinol) and 3.68 microg/mL (oxypurinol). Allopurinol crossed the placental barrier as shown by the average fetal C(max) values of 5.05 microg/mL at 1.47 h after allopurinol administration to the sow. In only one fetus low plasma oxypurinol concentrations were found. Incubations of subcellular hepatic fractions of sows and 24-h-old piglets confirmed that allopurinol could be metabolized into oxypurinol. In conclusion, we demonstrated that allopurinol can cross the placental barrier, a prerequisite for further studies evaluating the use of allopurinol as a neuroprotective agent to reduce the adverse effects following birth asphyxia in neonatal piglets.

Feeding daidzein to late pregnant sows influences the estrogen receptor beta and type 1 insulin-like growth factor receptor mRNA expression in newborn piglets.

The present study was undertaken to determine the tissue-specific expression of estrogen receptor beta (ERbeta), and the effects of a daidzein supplement to the diet of pregnant sows on the expression of ERbeta, and type 1 insulin-like growth factor receptor (IGF-1R) genes in newborn piglets by using semi-quantitative RT-PCR. Eight sows received a dietary supplement of daidzein at a dosage of 8 mg per kg feed from day 85 of gestation, and six sows were used as controls. After parturition, 2 male neonatal piglets were selected from each litter for sampling. ERbeta mRNA was detected in intestine, lung, thymus, kidney, pituitary and hypothalamus tissues, but not in heart, adrenal, skeletal muscle, liver or placental tissues. Daidzein treatment significantly increased the birth weight of male piglets and markedly reduced the level of ERbeta mRNA in the hypothalamus, but not in the pituitary. An up-regulation of IGF-1R gene transcription was observed in skeletal muscles of newborn piglets. In addition, the IGF-1R mRNA was found to be most abundant in pituitary and hypothalamus, followed by skeletal muscle, thymus, and liver tissues in decreasing order. Our results demonstrate that (1) ERbeta is expressed in a tissue-specific manner in newborn piglets, (2) daidzein down-regulates ERbeta gene expression in the hypothalamus, possibly indicating central effects of daidzein, and (3) daidzein influences fetal growth associated with higher IGF-IR gene expression in skeletal muscle.

Relationships between blood lipids and backfat thickness in growing pigs

Adipose triacylglycerol is mobilised during late pregnancy in humans and rats: the liberated fatty acids are incorporated into very low density lipoprotein (VLDL) by the liver and secreted into the blood stream. Similar hypertriacylglycerolaemia was also found in late-pregnant sows (Wright et al, 1995). It has been shown that VLDL can be separated into two subfractions by heparin-affinity chromatography. The proportion of VLDL-subfraction 2 (higher affinity for heparin) from pregnant sows was related to piglet mortality. The purpose of this investigation was to extend the study to seek relationships between fat deposition and plasma lipids, VLDL lipids and VLDL-subfractions in growing pigs. As most of the fat deposited in the adipose tissue of neonatal pigs is derived from the plasma lipoprotein, it seemed likely that the rate of fat deposition would be influenced by the concentration and nature of available lipoprotein in the plasma.

The use of an indicator diffusion procedure to measure the uterine blood flow in sows during the estrous cycle and pregnancy.

Uterine blood flow was measured in 16 nonpregnant sows and 13 pregnant sows at selected points during the estrous cycle and pregnancy. The 4-aminoantipyrine indicatordiffusion method was employed and measurements were made while the animals were under halothane anesthesia. In nonpregnant females, the uterine blood flow per kilogram of uterus was greater at 1 day and 19 days following estrus than at 5 or 14 days. The uterine weight was markedly increased at 14 days resulting in a slight elevation of total uterine blood flow at this stage as compared to the other three times during the cycle. Uterine tissue-uterine venous blood ratios indicated that the method was valid for nonpregnant measures but questionable in the case of pregnant uterine blood flow. In pregnant sows, the uterine blood flow per kilogram was greatest at 19 days and decreased to a relatively constant rate at 39, 75, and 95 days. Blood flow in the uterine artery was also measured in six late pregnant sows using the electromagnetic flowmeter.