Lactation In Sheep Research Articles

Whole genome-wide analysis of DEP family members in sheep (Ovis aries) reveals their potential roles in regulating lactation

BackgroundSheep milk is an attractive nutritional and functional food source. Some Dishevelled, Egl-10 and pleckstrin (DEP) domain-containing proteins can regulate lactation performance in mammals. However, systematic study of the role of sheep DEP family members in regulating lactation is currently lacking. This study aimed to reveal the roles of sheep DEP family members in lactation by exploring their genetic characteristics and functional features at the whole genome-wide level.ResultsTwenty DEP family members were identified in the sheep genome, and they can be divided into four major groups. Ka/Ks calculations suggest that the purifying selection is the main pressure acting on DEP genes. In the late pregnancy and lactation periods, the expression levels of eight DEP genes exhibited significant differences in the mammary gland. In addition, nutritional conditions have a great influence on the expression of DEP family members, and the DEP gene family underwent more expansion than the average gene family in the early stages of biological evolution. The Mirrortree assays indicated that the DEP family members coevolved in biological evolution.ConclusionsOur research provides a better understanding of the characters of the DEP domain-containing protein family and their potential roles in regulating lactation in sheep. Moreover, these results of our study may contribute to the genetic improvement of milk performance in dairy sheep breed.Graphical

PSIV-11 Effects of feeding a 50% cranberry vine pellet on milk components during lactation in sheep

Abstract The objective of this study was to examine the effect of feeding cranberry vine (CV) on milk components during early lactation as part of a larger study on the antiparasitic efficacy of CV supplementation on ewes during the periparturient period. Ewes were fed a 50% CV pellet (CVP; n = 12) or a control pellet (CON; n = 13) beginning at 102±1 d of pregnancy until d 65±1 postpartum. The CV pellet fed was formulated to be equivalent in digestible dry matter to the control pellet. BW was determined weekly during the study and milk samples were collected weekly during lactation. Data were analyzed in SAS with repeated measures. Ewe BW were similar at the start of study (180.36lbs ± 4.70lbs; P = 0.43) however by wk 8 postpartum CVP ewes weighed less than CON ewes (CON: 212.31lbs±7.86lbs; CVP: 185.58lbs±8.00lbs; P = 0.04). There was a treatment*wk effect observed for milk fat, protein and MUN (P ≤ 0.05). Ewes fed CVP exhibited reduced milk fat at wks 2 (CON: 6.75%±0.63%; CVP: 6.06%±0.58%; P = 0.03) and 5 (CON: 6.66%±0.37%; CVP: 5.54%±0.26%; P = 0.05), milk protein was reduced in CVP ewes at wk 2 (CON: 4.92%±0.12%; CVP: 4.72%±0.19%; P = 0.05) and MUN was greater at weeks 4 (CON: 22.89±0.7mg/dL; CVP: 27.93±0.85mg/dL; P = 0.01) and 8 (CON: 24.80±0.51mg/dL; CVP: 26.64±0.86mg/dL; P < 0.01) in CVP ewes. Somatic cell analysis is pending. In conclusion, CVP supplementation during lactation affects milk composition in sheep. Studies are underway to determine the effect of CV supplementation on additional metabolic parameters in pregnant and lactating ewes.

Negative effects of energy supplementation at peak lactation of sheep can be offset by the addition of Lactobacillus-fermented plant extracts.

Energy supplementation may reduce oxidative stress by correcting a negative energy balance, but in some contexts, it has been shown to increase oxidative stress, especially at peak lactation. The current experiment examined if a pelleted energy supplement with or without the addition of Lactobacillus-fermented seaweed or seaweed plus terrestrial plants extracts affected oxidative stress of ewes from late gestation through to weaning and ewe and lamb production from lambing to weaning. Treatments were either no supplement (CON-), a pelleted supplement only (CON+, 100 g/ewe per d), CON+ with seaweed extract only (SWO, 10 mL/ewe per day), or CON+ with seaweed plus an arrangement of terrestrial plant extract (SWP, 10 mL/ewe per d). Ewes (n = 160; mean initial BW = 72.3 ± 9.5 kg [mean ± SD]) were randomized to pastures (n = 4 pastures per treatment with 10 ewes each). After lambing, ewes with twins were reallocated to pastures (n = 3 pastures per treatment with 10 ewes each) according to lambing date. At 4 wk in milk, supplementation tended to reduce total antioxidant status (TAS; P = 0.10) and increased glutathione peroxidase (GPx) activity compared with nonsupplemented ewes (P = 0.04). The addition of seaweed and terrestrial plants extracts to the concentrate, that is, SWO and SWP, increased TAS and reduced GPx activity compared with CON+ (P < 0.01). Supplementation increased milk yield at weeks 4, 6, and 8 of lactation, and protein, lactose, and total milk solids yield at peak lactation (week 4; P < 0.05). The CON- ewes had greater somatic cell count than the supplemented ewes at weeks 4, 8, and 10 of lactation (P = 0.03). Our results suggest that energy supplementation, alone, increases oxidative stress of lactating ewes, which may relate to increased oxidative phosphorylation. Most importantly, these results indicate that in situations where energy supplementation is needed to increase animal performance, negative effects of energy supplementation around peak lactation can be offset by the addition of Lactobacillus-fermented plant extracts (SWO and SWP) to improve antioxidant status.

Small RNA deep sequencing reveals the expressions of microRNAs in ovine mammary gland development at peak-lactation and during the non-lactating period

MicroRNAs (miRNAs) are small non-coding RNAs that are involved in mammary gland development and lactation in livestock. Little is known about the roles of miRNAs in ovine mammary gland development, hence in this study the expression profiles of miRNAs of the mammary gland tissues of ewes at peak-lactation and during the non-lactating period were investigated using RNA sequencing. A total of 147 mature miRNAs were expressed in the two periods. Compared with peak-lactation, eight miRNAs in the non-lactating ewe mammary gland were significantly up-regulated, whereas fifteen miRNAs were down-regulated. A KEGG analysis revealed that the target genes of the up-regulated miRNAs were significantly enriched in lysosome, Wnt and MAPK signaling pathways, while the target genes of down-regulated miRNAs were significantly enriched in the PI3K-Akt signaling pathway, protein processing in endoplasmic reticulum and axon guidance. These results suggest that further study of the differentially expressed miRNAs could provide a better understanding of the molecular mechanisms of mammary development and lactation in sheep.

Nutritional Support for Small Ruminant Development Based on Oil Palm By-products

Biomass by-products or plant residues from the plantation system would play a crucial role in animal production since the utilization of forages from the underneath tree crops would be less or minimal when the palm oil crop mature. By-products generated from the palm oil system vary, but in relation to the animal production they could be generally categorized into the fibrous by-products and the non-fibrous (concentrate) by-products. Palm oil mill effluent (POME) and palm kernel cake (PKC) are concentrate by-products produced during the processing of palm oil extraction which have great potency to support sheep and goat production, although limiting factors such as contamination of shell and high copper level in PKC need to be considered in their utilization as feed. The fibrous palm oil by-products include oil palm fronds (OPF) and oil palm trunk (OPT) generated from the palm crop trees and oil palm empty fruit bunch (OPEFB) and palm pressed fiber (PPF) generated from processing of fresh fruits to yield crude oil. These fibrous by-products cannot meet the metabolisable energy required for high growth rate and for lactation of sheep and goats due to low DM digestibility, low crude protein content, low fermentable carbohydrate and low level of intake. Limited inclusion level in ration should be applied for those by-products to yield an acceptable production level of sheep and goats. Pretreatments (physical, chemical, and biological) gave some improvement in their nutritional qualities, however additional cost of pretreatments need to be considered. In the future, there would be a great challenge for the utilization of those fibrous by-products as animal feed since bioconversion of lignocellulosic materials to products such as chemicals (bioethanol, sugar, and bioplastic), fuels, and organic fertilizers are receiving greater interest. Some comparative advantages of these natural wastes are their relatively low cost, renewable and widespread in nature for used in an industrial operation.

Oxidative state of ewes with different number of parity during gestation and lactation

ABSTRACT: This study was conducted to assess the changes in some indicators of oxidative status during pregnancy and lactation in sheep of different parity. Dorset x Suffolk ewes were classified by number of parity: 1, 2 and ≥4. They were sampled before pregnancy and on the first, second, third, and fourth months, then on day 143 of pregnancy, as well as on day 5 after birth and after one month of lactation. Antioxidant capacity was found to have two reductions, the first during the second month of pregnancy and the second on day 5 of lactation. Susceptibility to lipid oxidation decreased with an increased number of parturitions. A reduction in lipid oxidation was observed on day 143 of gestation relative to the other samplings during gestation and lactation. Total glutathione peroxidase activity increased when the two reductions in antioxidant capacity took place. Ascorbic acid decreased during lactation and gestation; the lowest values were recorded in the third month of gestation. It is concluded that susceptibility to lipid oxidation decreases with the number of parturitions and that in ewes, during gestation and lactation, there is a mechanism that prevents lipid oxidation involving changes in antioxidant capacity, glutathione peroxidase and ascorbic acid.

Intergenerational impact of maternal overnutrition and obesity throughout pregnancy in sheep on metabolic syndrome in grandsons and granddaughters

We previously reported that maternal overnutrition and obesity (MO) throughout pregnancy and lactation in sheep (MOF0) decreases term fetal pancreatic β-cell numbers and increases perirenal adiposity producing hyperphagia, increased adiposity and insulin resistance in adult female offspring (MOF1) fed ad libitum. Pregnant female MOF1 exhibited increased blood glucose from mid to late gestation vs control F1 (CTRF1) though both groups ate only to NRC recommendations. MOF1 ewes delivered female offspring (F2) who like their MOF1 mothers exhibited increased abdominal adiposity and absent neonatal leptin surge. In the current work, we determined if adult MOF2 exhibited metabolic syndrome components when fed ad libitum. After weaning, MOF2 males (n = 5), MOF2 females (n = 6), CTRF2 males (n = 5), and CTRF2 females (n = 6) were fed to NRC requirements until 19 mo followed by 12-wk ad libitum feeding. Body weight and % fat increased (P < 0.01) in all F2 during this feeding trial. MOF2 males were heavier (P < 0.01) than CTRF2 males and females, and MOF2 females throughout the trial. By wk 8, baseline blood glucose concentrations increased (P < 0.001) in MOF2 females, but not other groups, remaining elevated throughout the trial. Baseline insulin was similar through wk 6, increasing (P < 0.05) at wk 8 in MOF2 females only. MOF2 female insulin returned to CTRF2 female levels during wk 10 and 12. The progressive increase of plasma glucose on wk 8 in association with increased insulin in MOF2 females but not other groups demonstrated a diet-induced increase (P < 0.001) in MOF2 female insulin resistance. The subsequent decline in insulin during wk 10 and 12 despite elevated glucose in MOF2 females is consistent with a decrease in glucose-stimulated pancreatic β-cell function. These data indicate that ad libitum feeding exceeds the pancreatic secretory response predisposing MOF2 females to hyperglycemia. Furthermore, there was a sex difference where MOF2 males increased body mass and MOF2 females displayed insulin/glucose dysregulation.

Comprehensive RNA-Seq profiling to evaluate lactating sheep mammary gland transcriptome.

RNA-Seq enables the generation of extensive transcriptome information providing the capability to characterize transcripts (including alternative isoforms and polymorphism), to quantify expression and to identify differential regulation in a single experiment. Our aim in this study was to take advantage of using RNA-Seq high-throughput technology to provide a comprehensive transcriptome profiling of the sheep lactating mammary gland. Eight ewes of two dairy sheep breeds with differences in milk production traits were used in this experiment (four Churra and four Assaf ewes). Milk samples from these animals were collected on days 10, 50, 120 and 150 after lambing to cover the various physiological stages of the mammary gland across the complete lactation. RNA samples were extracted from milk somatic cells. The RNA-Seq dataset was generated using an Illumina HiSeq 2000 sequencer. The information reported here will be useful to understand the biology of lactation in sheep, providing also an opportunity to characterize their different patterns on milk production aptitude.

Salsolinol Up-Regulates Oxytocin Expression and Release During Lactation in Sheep.

Salsolinol (1-methyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline) is a dopamine-derived compound present in the central nervous system and pituitary gland. Several previous studies on lactating sheep and rats have reported that salsolinol plays a crucial role in the regulation of prolactin secretion. The present study investigated the effects of salsolinol, which was infused into the third ventricle of the brain, on oxytocin expression and release in lactating sheep, 48 h after weaning of 8-week-old lambs. Serial 30-min infusions of salsolinol and vehicle were performed at 30-min intervals from 10.00 to 15.00 h. Blood samples were collected every 10 min. The supraoptic nucleus (SON), paraventricular nucleus (PVN) and posterior pituitary were collected immediately after the experiment. Expression levels of mRNAs for oxytocin and peptidylglycine α-amidating monooxygenase (PAM), the terminal enzyme in the oxytocin synthesis pathway, were measured using a real-time polymerase chain reaction. Oxytocin peptide content in the posterior pituitary was measured by an enzyme-linked immunosorbent assay, and plasma oxytocin concentration was measured by radioimmunoassay. Salsolinol treatment significantly up-regulated oxytocin and PAM gene expression in the SON (P < 0.01 and P < 0.05, respectively), PVN (P < 0.01 and P < 0.05, respectively) and posterior pituitary (P < 0.05 and P < 0.05, respectively). Oxytocin peptide content in the posterior pituitary and the area under the response curve of plasma oxytocin were significantly (P < 0.05 and P < 0.01, respectively) higher in salsolinol-treated sheep than in control animals. The present study shows for the first time that salsolinol stimulates oxytocin secretion during lactation in sheep.

Quantification of milk yield and composition changes as affected by subclinical mastitis during the current lactation in sheep

The aim of this work was to quantify, on a half-udder basis, the changes in ewe milk yield and composition caused by unilateral subclinical mastitis within the current lactation. Fluctuations due to production level, infection severity, time from the onset of infection, and lactation curves were also studied. Yield and composition of milk from half-udders of unilateral infected ewes were compared between them and with a set of healthy halves using a mixed model. The experiment was completed with a whole-udder approach on the same animals. To test the effect of intramammary infection (IMI) in the 7wk following the onset of infection, 20 ewes that acquired unilateral subclinical mastitis during lactation and 40 healthy ewes were used. Another group of 20 unilaterally infected ewes from wk 1 of lactation and other 40 healthy ewes were studied to test the effect of IMI on lactational milk yield and composition. The individual milk loss in ewes infected during lactation was 15% for the 7wk following the onset of infection, and 6.6% more milk was produced by the uninfected half to compensate milk lost by the infected half. Lactational milk yield loss in ewes infected from wk 1 postpartum was 17%. The changes in milk yield were noticed from the week of infection diagnosis. The production level of animals influenced the milk yield changes caused by IMI in such a way that the more productive ewes lost more milk, although these losses were proportional to their production level. On the other hand, infection severity affected milk loss between glands, being more pronounced as somatic cell count increased. A clear decrease of lactose content and casein:protein ratio due to subclinical IMI was observed and it remained throughout the postinfection period. Improving udder health status is necessary to maintain milk production and quality in dairy ewes during lactation.

The freezing point of raw and heat treated sheep milk and its variation during lactation

The freezing point of milk is an important indicator of the adulteration of the milk with water, but heat treatment may also affect its value. The aim of this study was determine freezing point of raw and heat treated sheep milk and its variation during lactation. The freezing point was determined in 42 bulk tank raw sheep milk samples and 42 pasteurized milk samples collected during lactation of sheep at one ecofarm in Moravian Walachia (Valašsko in the Czech Republic). The freezing point was determined in accordance with the standard ČSN 57 0538 using a thermistor cryoscope. The average freezing point of raw milk was -0.617 ± 0.052 °C, with a range from -0.560 to -0.875 °C. The freezing point was lower in the first months of lactation and increased at the end of lactation. The freezing point correlated (r = 0.8967) with the content of total non-fat solids. The average freezing point of sheep milk pasteurized at 65 °C for 30 min was -0.614 ± 0.053 °C, with a range from -0.564 to -0.702 °C. The median of freezing point differences between raw and pasteurized milk was 0.004 °C. Our study extends data about physico-chemical properties of sheep milk and registers for the first time specific changes in the freezing point value of sheep milk by heating.

Mapping quantitative trait loci (QTL) in sheep. IV. Analysis of lactation persistency and extended lactation traits in sheep

BackgroundIn sheep dairy production, total lactation performance, and length of lactation of lactation are of economic significance. A more persistent lactation has been associated with improved udder health. An extended lactation is defined by a longer period of milkability. This study is the first investigation to examine the presence of quantitative trait loci (QTL) for extended lactation and lactation persistency in sheep.MethodsAn (Awassi × Merino) × Merino single-sire backcross family with 172 ewes was used to map QTL for lactation persistency and extended lactation traits on a framework map of 189 loci across all autosomes. The Wood model was fitted to data from multiple lactations to estimate parameters of ovine lactation curves, and these estimates were used to derive measures of lactation persistency and extended lactation traits of milk, protein, fat, lactose, useful yield, and somatic cell score. These derived traits were subjected to QTL analyses using maximum likelihood estimation and regression analysis.ResultsOverall, one highly significant (LOD > 3.0), four significant (2.0 < LOD < 3.0) and five suggestive (1.7 < LOD < 2.0) QTL were detected across all traits in common by both mapping methods. One additional suggestive QTL was identified using maximum likelihood estimation, and four suggestive (0.01 < P < 0.05) and two significant (P < 0.01) QTL using the regression approach only. All detected QTL had effect sizes in the range of 0.48 to 0.64 SD, corresponding to QTL heritabilities of 3.1 to 8.9%. The comparison of the detected QTL with results in cattle showed conserved linkage regions. Most of the QTL identified for lactation persistency and extended lactation did not coincide. This suggests that persistency and extended lactation for the same as well as different milk yield and component traits are not controlled by the same genes.ConclusionThis study identified ten novel QTL for lactation persistency and extended lactation in sheep, but results suggest that lactation persistency and extended lactation do not have a major gene in common. These results provide a basis for further validation in extended families and other breeds as well as targeting regions for genome-wide association mapping using high-density SNP arrays.

Reduction of milk records per lactation in sheep

Milk recording on sheep in Slovenia was started in the beginning of nineties. It is done in one month interval. Seasonal recording in flock starts when the first animals are weaned twenty-eight days. The recording in flock is continuing to the end of lactation of last animal, approximately nine mounts. The method is accurate but expensive. Lactation yields of milk, fat, proteins and lactose, calculated from reduced number of milk records were compared with officially estimated milk yields. The reductions were: records in first thee (3M), first four (4M), first five (5M) and first six (6M) months of lactation and two reductions on two records in six months. In first case the recording starts within first month after weaning (3U) and in second case in second month after weaning (3P). Yields are mostly overestimated. In some cases are overestimations yields very high. The correlations for milk yield were between 0.883 and 0,915, for fat yield between 0.784 and 0.831, for proteins yield 0.822 and 0.866, and for lactose yield between 0.835 and 0.873. The lowest correlations were found in 3M, then in 3U and 3P followed by 4M, 5M and 6M. The gain from 5M to 6M is not very impressive. I some cases will led simple reduction of milk records per lactation to very incorrect results. Reduced number of milk records demands more sophisticated estimation of milk and milk ingredients yields per lactation.

Effect of a Calcium Soap of Fatty Acids on Reproductive Characteristics and Lactation Performance of Fat-Tailed Sheep

Experiments were carried out to study the effect of feeding Megalac, calcium soaps of fatty acids (protected fat), on reproduction and lactation of sheep. In the first experiment, 20 Ghezel and 20 Mehraban cyclic fertile ewes (4-5 years old) were randomly allotted to 4 groups. The control group was fed with a balanced ration and the other groups received the same diet as well as a daily allowance of 40 g non-protected fat (NP), 40 g protected fat (LP), or 80 g (HP) protected fat. The ewes were fed with their respective rations for one cycle length. Blood samples were collected and analyzed for progesterone (P4), cholesterol (CHOL), High Density Lipoproteins (HDL), Low Density Lipoproteins (LDL) and triacylglycerols (TG). The ewes were slaughtered on their next estrous period and the size and number of follicles in ovaries were recorded. There were no significant effects of feeding fat on ovarian weights, cycle length and follicular numbers in each class, or on the size of the largest follicle. Serum concentrations of P4, CHOL, TG and HDL were greater for HP ewes as compared with the control ewes (p<0.05). In the second experiment, effects on lactation and lamb performance of feeding protected fat during mating, late gestation and early lactation were studied in Mehraban ewes. Milk and fat yields on day 25 of lactation were significantly increased by feeding protected fat. Protected fat resulted in lower weight loss in ewes and a higher lamb birth weight. Average daily weight gain of lambs from birth to day 60 and the weaning weight of lambs were increased by feeding protected fat (p<0.05). In conclusion, calcium soaps of fatty acids increased serum P4 between days 10 to 14 of the cycle which may be beneficial to early pregnancy maintenance. Protected fat seemed to have a beneficial effect on milk yield, fat yield, lamb daily gain, lamb birth weight and ewe weight loss.

The relationships between intake and net portal fluxes of energy metabolites in ruminants: A meta-analysis

In a research programme aiming at characterising the energy value of ruminant diets by the net portal energy fluxes in ruminants, the present work focused on the relationships between intakes of both dry matter (DMI) and digestible organic matter (DOMI) and the portal blood flow and the net portal fluxes of oxygen (O 2), volatile fatty acids, β-hydroxybutyrate, glucose and lactate in sheep and growing cattle. Response equations were generated, expressed as a function of liveweight (LW), using meta-analysis on published that were compiled into the FLORA (FLux of nutrients through the Organs and tissues of Ruminant Animals) database and that investigated changes in intake at constant dietary metabolisable energy (ME) contents within experimental groups. The experimental groups in the selected data set were predominantly adult sheep ( n = 17), with nine experimental groups on growing cattle and only one experimental group on lactating dairy cows. Intake range was larger in sheep than in growing cattle (0–35 g/d/kg LW versus 0–23 g/d/kg LW, respectively), and the types of diets fed also differed, with sheep predominantly being fed forage-rich diets (60% of experimental groups). Blood flow and portal O 2 consumption showed curvilinear relationships; however the response equations generated for nutrients were best described by linear relationships. With the exception of glucose net portal flux, 70–95% of variation was explained by the models generated. The magnitude of the response equations was largely different between species, and this may also include differences in diets and/or physiological state between the datasets. Both DMI and DOMI were good predictors of the influence of a change in intake level on net portal fluxes of energy metabolites. Subsequent work needs to focus on the influence of diet composition ( i.e., dietary ME content).

Lactation induces hypoleptinaemia and activates orexigenic hypothalamic pathways in sheep

The initial period of lactation in domestic ruminants is usually characterised by both hyperphagia and negative energy balance (Barber et al, 1997). The factors regulating the hyperphagia of lactation are not well understood. Leptin is a peptide hormone which is secreted by adipocytes, and which acts on a number of neuropeptides and receptors in the hypothalamus to regulate appetite and energy balance (Spiegelman and Flier, 2001). The aim of this study was to investigate the role of leptin in the hyperphagia of lactation in sheep.

Leptin in ruminants. Gene expression in adipose tissue and mammary gland, and regulation of plasma concentration

This paper reviews data on leptin gene expression in adipose tissue (AT) and mammary gland of adult ruminants, as well as on plasma leptin variations, according to genetic, physiological, nutritional and environmental factors. AT leptin mRNA level was higher in sheep and goat subcutaneous than visceral tissues, and the opposite was observed in cattle; it was higher in fat than in lean selection line in sheep; it was decreased by undernutrition and increased by refeeding in cattle and sheep, and not changed by adding soybeans to the diet of lactating goats; it was increased by injection of NPY to sheep, and by GH treatment of growing sheep and cattle. Insulin and glucocorticoids in vitro increased AT leptin mRNA in cattle, and leptin production in sheep. Long daylength increased AT lipogenic activities and leptin mRNA, as well as plasma leptin in sheep. Mammary tissue leptin mRNA level was high during early pregnancy and was lower but still expressed during late pregnancy and lactation in sheep. Leptin was present in sheep mammary adipocytes, epithelial and myoepithelial cells during early pregnancy, late pregnancy and lactation, respectively. Plasma leptin in cattle and sheep was first studied thanks to a commercial “multi-species” kit. It was positively related to body fatness and energy balance or feeding level, and decreased by β-agonist injection. The recent development of specific RIA for ruminant leptin enabled more quantitative study of changes in plasma leptin concentration, which were explained for 35–50% by body fatness and for 15–20% by feeding level. The response of plasma leptin to meal intake was related positively to glycemia, and negatively to plasma 3-hydroxybutyrate. The putative physiological roles of changes in leptin gene expression are discussed in relation with published data on leptin receptors in several body tissues, and on in vivo or in vitro effects of leptin treatment.

Plasma volume expansion with solutions of hemoglobin, albumin, and Ringer lactate in sheep.

We have measured plasma volume expansion (Evans blue and hematocrit changes) and hemodynamic responses in conscious hemorrhaged and normovolemic splenectomized sheep after a 30-min infusion of either 20 ml/kg of diaspirin cross-linked hemoglobin (DCLHb), 20 ml/kg of human albumin (Alb), or 60 ml/kg of a solution of Ringer lactate (RL). All regimens expanded blood volume and increased blood pressure and cardiac output after hemorrhage. However, only 15 +/- 3% of the infused volume of RL was evident as intravascular expansion 10-min postinfusion, compared with 67 +/- 16% and 139 +/- 139% for Alb and DCLHb, respectively. DCLHb infusions were associated with higher blood pressures and lower cardiac outputs compared with RL and Alb infusions, but the increased oxygen content of blood with DCLHb resulted in systemic delivery of oxygen similar to that of the other infusions. These differences in hemodynamics and vascular volume continued for 6 h, and at 24 h vascular volume and all hemodynamics were similar in all three groups. The better volume expansion with DCLHb may be due to greater mobilization of endogenous interstitial protein or reduced transcapillary loss as total intravascular endogenous plasma protein increased after infusion of DCLHb, whereas there was an apparent loss of endogenous intravascular protein after infusions of Alb and RL. Vasoconstriction by DCLHb is one mechanism that could lower blood-to-tissue transport of fluid and protein. In addition to its oxygen-carrying capacity and vasoactivity, DCLHb is associated with volume expansion properties out of proportion to its colloid osmotic pressure.

Insulin secretion and intestinal peptides during lactation in sheep.

Intravenous infusions of glucose and/or glucagon-like peptide-1(7-36)-amide (GLP) or somatostatin-28 (S28) were administered to dry and lactating sheep and changes in plasma glucose and serum insulin were followed before, during and after infusion. Basal serum insulin concentrations were significantly lower in lactating sheep but there was no significant difference in plasma glucose concentrations. During glucose infusion, changes in serum insulin concentrations were diminished by comparison with those in dry animals. GLP stimulated insulin secretion during hyperglycaemia in both dry and lactating sheep but, proportionately, the response was significantly greater in the lactating animals. S28 inhibited glucose-stimulated insulin secretion in both dry and lactating sheep and there was no significant difference in the extent of the inhibition between the two physiological states. S28 infusion also inhibited the secretion of GLP from the intestinal tract and this effect was significantly greater in the lactating animals. The results demonstrate a difference in response in the lactating animal to GLP compared with S28. A possible explanation of the difference is a decreased sensitivity (i.e. increased Km) of the pancreas to the insulinotropic effects of GLP but an increased sensitivity to the inhibitory effects of S28 at tissues other than the pancreas in lactation.

Plasma Volume Expansion with Solutions of Hemoglobin, Albumin and Ringer's Lactate in Sheep

Plasma Volume Expansion with Solutions of Hemoglobin, Albumin and Ringer's Lactate in Sheep