Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LACTATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed1986

Efficiency of food utilization by pregnant and lactating sows. 2. The influence of isocaloric diets with different protein levels on pregnancy and lactation.

The efficiency of utilization of feed energy as digestible, metabolizable and net energy is similar in pregnant and lactating sows irrespective of the stage of these physiological conditions. This efficiency with the value of about 71% resembles the one found in the growing and fattening pigs, which enables us to use, for this category of animals, the same system offered evaluation and of the energy requirements based on fat nutritive units. The maintenance energy requirement expressed in ME varies from 467 kJ/kg 0.75 in pregnant sows to 512 kJ/kg 0.75 in lactating sows, for the suckling piglets having intermediary value of 498 kJ/kg 0.75. The efficiency of utilization of diets protein for maintenance and for synthesis is also similar for these categories of pigs, varying from 71% in lactating sows to 75-76% in pregnant sows. In suckling piglets we had recorded an efficiency of DCP utilization which varies parabolically with size of the ingesta and therefore with that of weight gain. The DCP maintenance requirement expressed in g N dig./kg 0.75 varies within narrow limits between 0.345 g N in suckling piglets 0.380 g N in pregnant sows; In lactating sows we have detected an intermediary value of 0.355 g N. Based on these experimental data and also using recent experimental results obtained by Schiemann and Beyer (1984) regarding the energy and N content of the foetuses, of the organs of reproductions and of milk, we could calculate the energy and protein requirements. These requirements when compared with the values used in our country show us higher values of energy in pregnant and lactating sows and lower values of protein for the same categories, including the piglets, where we have also found lower values for the energy too.

Animals↗
PubMed1993

[Energy and nitrogen metabolism of pregnant and lactating sows and suckling piglets. 3. Chemical composition and energy content of the animal body fractions as well as portions of the animal body fractions of empty body of nonpregnant, pregnant and lactating sows].

The study is based on the results obtained from the slaughter of 5 sows on the first day of pregnancy and the first day of the experiment respectively (pregnant and non-pregnant sows resp.), of 43 pregnant sows on the 56th, 84th, 98th, 105th and 113rd day of gestation as well as 17 lactating sows on the 26th day of lactation. The animal bodies of pregnant sows were divided in 15 fractions and those of non-pregnant and lactating sows in 12 fractions. The investigations were carried out with 3 x 3 variants of litter number (1, 2, 4) and energy supply (120, 100, 80% of requirement recommendation). The chemical composition and the energy content of the animal body fractions as well as their relative portions of the empty body were largely constant during the course of gestation with the exception of the reproductive organs and the conception products. The physiological stage of lactation connected with limited mobilization of body reserves resulted in a reduction in fat content of some body fractions as well as a limited increase of the portions of body organs contrary to the portions of body tissues of the empty body. In comparison with sows of litter numbers 1 and 2 the sows of litter number 4 were characterized by higher portions of bones and meat, valuable parts as well as by smaller portions of depotfat and meat from head and belly of empty body. The raising of the energy supply of the pregnant sows increased the portion of the depotfat and decreased the portion of the meat, valuable parts of the empty body. The chemical composition of the reproductive organs and the conception products as well as the portions of these fractions of the empty body were influenced strongly from the course of the gestation and lactation resp. The portions of the reproductive organs and of the conception products are small (related to energy < or = 5.7 and < or = 2.6% resp.)

Abattoirs↗
PubMed1994

Effect of extracellular lactate on growth of rumen lactate producers.

The addition of Na-lactate (50-150 mmol/l) to media with glucose had only marginal effect on the growth of rumen lactate-producing bacteria at pH between 6.5 and 5.8. Butyrivibrio fibrisolvens was somewhat more sensitive to external lactate than Streptococcus bovis, Lactobacillus fermentum and Selenomonas ruminantium. It can be concluded that rumen lactate producers, which proliferate at the onset of rumen lactic acidosis, are not influenced by the lactate accumulation, except some non-specific osmotic effects.

Animals↗
PubMed1996

Effect of skim milk supplementation of the maternal diet on lactational amenorrhea, maternal prolactin, and lactational behavior.

Effect of skim milk supplementation of the maternal diet on lactational amenorrhea was studied in 30 pairs of healthy lactating women matched for parity, body mass index, and previous experience of lactational amenorrhea. Supplementation of the maternal diet had no significant effect on the time of resumption of regular menstruation or ovulation, maternal prolactin concentrations, breast-feeding pattern, maternal body mass index, or infant weight. However, the supplemented group breast-fed nearly exclusively (supplemental feeds were introduced but did not exceed 20% of total feeds) for a significantly longer duration (P < 0.05) than did the control group. Previous experience of lactational amenorrhea was significantly positively correlated with the time of resumption of menstruation in the supplemented (P < 0.01) and control (P < 0.05) groups when frequency of breast-feeding, maternal body mass index, and supplementary feeds to the infant were controlled for. Thus, maternal nutritional supplementation does not appear to affect the contraceptive benefit of lactation when the frequency of breast-feeding is not compromised but apparently lengthens the duration of nearly full breast-feeding.

Adult↗
PubMed1976

myo-Inositol metabolism during lactation and development in the rat. The prevention of lactation-induced fatty liver by dietary myo-inositol.

Effects of dietary myo-inositol deprivation were examined during prenatal and postnatal development and during lactation in the rat. The deficient diet contained no detectable myo-inositol while the supplemented diet contained 0.5% (w/w) myo-inositol while the supplemented diet ct contained 0.5% (w/w) myo-inositol at the expense of sucrose. Both diets contained 25% casein, adequate amounts of all known vitamins, choline, and essential fatty acids as well as 0.5% (w/w) phthalylsulfathiazole to depress myo-inositol contribution to the diet by microorganisms. Pregnant rats of the Holtzman strain were fed the respective diets during gestation and lactation, and pups were fed the corresponding diet after weaning until 3 months of age. There were no significant differen-es in body weight between experimental groups. Supplementation of the diet with myo-inositol significanly increased the levels of myo-inositol in plasma, liver, kidney, and intestine of pups at all ages examined, and significantly increased the levels of myo-inositol in the milk and mammary tissue during lactation. During lactation, the myo-inositol deprived dams developed severe fatty livers (31% w/w) characterized by diminished phosphatidyl-inositol (50%) and total phospholipid phosphorus (57%) levels as compared with controls. After weaning, the liver lipid content of the myo-inositol deprived dams returned to normal (4.5%). The data suggest that a possible threshold level of free myo-inositol (approximately 0.15 mumoles/g lipid-free tissue) was required to prevent fatty liver in lactating dams under these dietary conditions. Effects of the deficient diet on fertility were also examined. Based on sperm count and production of offspring, there were no differnences between the experimental and control males. Females of both groups showed equal ability to produce offspring.

Amniotic Fluid↗
PubMed1977

Comparative studies of lactate dehydrogenases in lactic acid bacteria. Amino-acid composition of an active-site region and chemical properties of the L-lactate dehydrogenase of Lactobacillus casei, Lactobacillus curvatus, Lactobacillus plantarum, and Lactobacillus acidophilus.

The molecular weight, the amino acid composition and the N-terminal and C-terminal amino acids of two allosteric (Lactobacillus casei, L. curvatus) and two non-allosteric (L. plantarum, L. acidophilus) L-lactate dehydrogenases, purified to homogeneity by affinity chromatography, were determined. The amino acid composition of the only tryptic peptide unequivocally common to the fingerprints of the 4 enzymes is virtually identical with that of the arginine peptide, called Arg6 of the the substratebinding site of the L-lactate dehydrogenase dehydrogenase of several animals. However, the 'essential' cysteine residue 165 is replaced by threonine, as it is in the L-lactate dehydrogenase of lobster. In addition, the 4 bacterial peptides differ by one or two changes in single amino acid residues from each other as well as from those of animals. The data indicate that not only the animal L-lactate dehydrogenases, but also the allosteric and lactate dehydrogenases from bacterial sources may have evolved from a common gene.

Amino Acids↗
PubMed1987

Metabolic adaptations in mouse mammary gland during a normal lactation cycle and in extended lactation.

The development and involution of mouse mammary tissue was measured in terms of changes in the cell population and the synthetic capacity of cells during the course of pregnancy, lactation and natural weaning, and after lactation was extended by introduction of foster litters of younger pups. Synthetic capacity was assessed by measuring the activities of several key enzymes closely concerned with the synthesis of milk constituents together with other constitutive enzymes. The capacity of the tissue to synthesize lactose and casein was also measured using short-term cultures of freshly prepared mammary explants. Results showed that the mammary cell population began to increase and differentiate around the time of parturition. Cell numbers increased up to day 5 of lactation, whereas cellular differentiation continued through lactation until day 15, around the time of peak milk yield. After day 15 there was a sharp drop, followed by a gradual decline in synthetic capacity and cell population, as pups were weaned. Substitution of younger pups for the natural litter at day 15 prevented the normal fall in milk secretion. In this case, mammary cell number remained at day 15 levels; cellular differentiation was also maintained to a considerable degree, although several markers of differentiation decreased during extended lactation.

Adaptation, Physiological↗
PubMed2004

Major role of NAD-dependent lactate dehydrogenases in aerobic lactate utilization in Lactobacillus plantarum during early stationary phase.

NAD-independent lactate dehydrogenases are commonly thought to be responsible for lactate utilization during the stationary phase of aerobic growth in Lactobacillus plantarum. To substantiate this view, we constructed single and double knockout mutants for the corresponding genes, loxD and loxL. Lactate-to-acetate conversion was not impaired in these strains, while it was completely blocked in mutants deficient in NAD-dependent lactate dehydrogenase activities, encoded by the ldhD and ldhL genes. We conclude that NAD-dependent but not NAD-independent lactate dehydrogenases are involved in this process.

Acetates↗
PubMed1977

pH effects on lactate and excess lactate in relation to O2 deficit in hypoxic dogs.

Both hypoxemia and alkalemia increase arterial lactate levels, but excess lactate (XL) may be better related to the true O2 deficit and less subject to the pH effect upon glycolysis. To test this idea, 50 anesthetized (30 ml/kg pentobarbital sodium) and paralyzed dogs in five groups were ventilated with low O2 mixtures. Arterial pH was altered by CO2, hyperventilation, and HCO3- so that the average pH of the five groups were 6.99, 7.21, 7.34, 7.53, and 7.54 (+ propranolol). Pyruvate and lactate levels rose at rates roughly corresponding to pH. In all animals, rise of lactate (deltaL), XL and net O2 deficit were linear with time and the slope accurately described the rate of rise. When the ratio of XL rate deltaL rate was plotted against pH, it increased toward unity as pH decreased to 6.9. The ratio of deltaL rate to true O2 deficit rate also showed a significant pH effect by increasing with pH. Ratio of XL rate to true O2 deficit rate, on the other hand, was independent of pH. XL may correct for red cell lactate production which is not affected by O2 supply but is influenced by pH.

Animals↗
PubMed1979

The suckling-induced rise of plasma prolactin in lactating rats: its dependence on stage of lactation and litter size.

The response of plasma prolactin in vigorous suckling was measured in lactating rats which had been isolated for 10-12 h from their offspring. Plasma prolactin was investigated during suckling at various stages of lactation. The results demonstrate that prolactin responds maximally to suckling already in the first days of lactation. In the second half of the lactation period, the prolactin rise in the plasma induced by suckling decreases gradually; this is not due to a reduced suck-intensity of older pups. A relationship is found between the height of the suckling-induced prolactin rise and litter size. The data suggest that during suckling in the first weeks of lactation the pituitary secretes large amounts of prolactin at a constant rate. It is speculated that in the first minutes of suckling, receptors may clear considerable amounts of released prolactin from the circulation.

Age Factors↗
PubMed1997

A further study of seminal plasma: lactate dehydrogenase and lactate dehydrogenase-X activities and diluted semen absorbance.

Activities of total lactate dehydrogenase, which plays an important role in providing energy for cell metabolism, lactate dehydrogenase-X, an isoenzyme of lactate dehydrogenase supposed to be specific for germinal epithelium activity, diluted semen absorbance and some other properties have been measured in 51 seminal plasma samples. Aiming to study its clinical use as a marker of seminiferous epithelium activity, determination of isoenzyme-X and investigation of correlation between it and the spermiogram properties were carried out. Besides lactate dehydrogenase and lactate dehydrogenase-X activity, their ratio and diluted semen absorbance were correlated with the different properties of the spermiogram, the best correlation of the enzymes being obtained with the total sperm count and motile sperm count. Correlation of diluted semen absorbance with the total sperm count and motile sperm count was also noted, whereas it did not correlate with sperm concentration and motility rate. The data suggests the clinical utility of these properties as reliable markers for both germinal activity and spermatozoid quality when "total sperm count" and "mobile sperm count" are used to define sperm properties instead of just sperm concentration and motility rate.

Biomarkers↗
PubMed1978

Mammary gland prolactin receptor and pituitary prolactin secretion in lactating mice with different lactational performance.

SHN female mice, a high mammary tumour strain, are superior to SLN, a low mammary tumour strain, in lactational performance. Mammary gland prolactin receptor and pituitary prolactin secretion during lactation were compared between these strains. The binding activity, the number of receptor sites per mg tissue and the association constant were measured by the in vitro incubation of mammary gland slices with 125I-labelled bovine prolactin, and the pituitary and plasma levels of prolactin were assayed by homologous radioimmunoassay. There was only a slight difference between strains in any of the parameters for prolactin receptor and for prolactin secretion on either day 4 or day 9 of the first lactation. Almost all the correlation coefficients between each parameter for prolactin receptor and the pituitary or plasma level of prolactin were not statistically significant. These findings suggest that any parameter for prolactin examined in this study is not always directly indicative of lactational performance and further show that the individual variation in the pituitary prolactin secretion during lactation is not so great as to alter the prolactin receptor.

Animals↗
PubMed1998

Ontogeny of the opioidergic regulation of LH and prolactin secretion in lactating sow. I: failure of naloxone to antagonize suckling-induced changes in LH and prolactin secretion in early lactation, irrespective of pattern of administration.

The principal aim of this study was to investigate the ontogeny of an opioidergic mechanism mediating the suckling-induced inhibition of LH secretion during lactation in sows. In contrast to an increase in LH secretion in response to naloxone treatment on days 10 and 11 of lactation (P < 0.05), a single injection of 2 mg naloxone kg-1 at 39, 51, 63, or 75 h post partum had no effect. However, the last of four injections of 2 mg naloxone kg-1 given at 12 h intervals to group IV sows did elicit a positive LH response (P < 0.05). Multiple injections of 1 mg naloxone kg-1 at 3 h intervals over 30 h on day 10-11 consistently increased (P < 0.05) mean plasma LH with no evidence of induced refractoriness to repeated use of the antagonist. Similarly, naloxone did not affect mean plasma prolactin in the immediate postpartum period, but either repeated naloxone treatments on day 10-11 or single naloxone injections on day 10 or 11 of lactation decreased plasma prolactin (P < 0.05). Therefore, the regulation of LH and prolactin secretion in lactating sows changes with time post partum. An opioid-dependent mechanism is an important component of the suckling-dependent regulation of LH and prolactin secretion in established lactation, but not during the first 72 h postpartum period.

Animals↗
PubMed2003

Effect of hypothyroidism on hormone profiles in virgin, pregnant and lactating rats, and on lactation.

Thyroid dysfunctions can produce reproductive problems. Untreated maternal hypothyroidism has serious consequences on development of offspring, resulting in stunted growth and mental retardation. The effects of propylthiouracyl-induced hypothyroidism (0.1 g l(-1) in drinking water starting 8 days before mating, or given to virgin rats for 30 or 50 days) on the serum profiles of hormones related to reproduction and mammary function (prolactin, growth hormone (GH), progesterone, corticosterone, oestradiol, insulin-like growth factor I (IGF-I), thyroid-stimulating hormone (TSH), triiodothyronine and tetraiodothyronine), and on mammary function in virgin, pregnant and lactating rats, were investigated. Propylthiouracyl treatment severely decreased circulating triiodothyronine and tetraiodothyronine concentrations, and increased serum TSH concentrations. Virgin rats showed prolonged periods of vaginal dioestrus, increased circulating progesterone concentrations and afternoon peaks of prolactin concentration, which are indicative of prolactin-induced pseudopregnancy. Propylthiouracyl-treated virgin rats had mammary development comparable to that of midpregnancy, and half of these rats had increased mammary casein and lactose concentrations. Serum prolactin concentrations were decreased on the afternoon of day 5 of pregnancy, increased during late pregnancy (days 15-21) and were normal during lactation. Circulating GH concentrations decreased on days 15-21 of pregnancy, whereas progesterone concentrations increased during late pregnancy and early lactation. Circulating oestradiol (measured in late pregnancy and in virgin rats), IGF-I and corticosterone concentrations were decreased. Although assessment of mammary histology showed no differences in extent of development, casein content was increased in propylthiouracyl-treated rats on day 21 of pregnancy; litter growth was severely reduced and at day 20 of age the pups were hypothyroid, with decreased GH serum concentrations. An acute suckling experiment was performed on days 10-12 of lactation to determine whether some impairment in mammary function or the suckling reflex might account for these differences. After an 8 h separation of mothers from their litters and 30 min of suckling, circulating prolactin values were not affected by propylthiouracyl treatment, but serum oxytocin concentration and milk excretion were reduced. In conclusion, hypothyroidism induces various alterations in the hormone profiles of virgin and pregnant rats, and induces pseudopregnancies and mammary development in virgin rats. These alterations do not appear to have an overt impact on the outcome of pregnancy and on mammary function during lactation, with the exception of the milk ejection reflex, which may account at least partially for the reduced litter growth.

Animals↗
PubMed2001

Effect of nutrient intake in lactation on sow performance: determining the threonine requirement of the high-producing lactating sow.

Reproductive performance is steadily increasing within the pork industry; logically, amino acid requirements need to be redefined for sows producing larger litters. The objective of this study was to determine the threonine requirement of the high-producing lactating sow and to determine the effect of lysine on this requirement. A total of 419 PIC C-15 sows were assigned randomly to treatment within parity groups (1, 2, and 3+) and gestation treatment at d 110 of gestation. Lactation diets were formulated to contain 0.80% total lysine (tLYS) with 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, or 0.65% total threonine (tTHR) or 1.06% tLYS with 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or 0.70% tTHR. Litters were standardized to a minimum of 11 piglets within 48 h after farrowing, and sows had free access to feed throughout lactation (lactation length = 20.1 +/- 0.1 d). Sow ADFI exceeded expectation, averaging 6.90, 7.40, and 7.20 kg/d for Parities 1, 2, and 3+, respectively. Daily tLYS intake was 58 g/d (47 g of apparent ileal digestible lysine [dLYS] per day) and 74 g/d (59 g dLYS/d) for the low- and high-lysine group, respectively. Lysine intake did not affect sow or litter performance (P > 0.10). Sows gained an average of 4.8 kg in lactation. Using regression analysis, BW gain was maximized at 0.54% tTHR for all parity groups (quadratic; P < 0.05). Litter weaning weight (67.1, 67.9, and 66.2 kg for Parities 1, 2, and 3+, respectively) and litter weight gain (2.49, 2.53, and 2.44 kg/d for Parities 1, 2, and 3+, respectively) were maximized at 0.53% tTHR using regression analysis, for all parity groups (quadratic; P < 0.05). Based on regression analysis, plasma urea nitrogen on d 10 and 18 was minimized at 0.54% tTHR (P < 0.05). Lysine levels in excess of 58 g of tLYS/d did not benefit sow or litter performance. The requirement for threonine to minimize sow tissue mobilization was 37, 40, and 38 g tTHR/d (28, 30, and 30 g of apparent ileal digestible threonine [dTHR] per day) for Parities 1, 2, and 3+ sows, respectively. The threonine required to maximize litter performance was 36, 39, and 38 g of tTHR/d (28, 30, and 29 g of dTHR/d) for Parities 1, 2, and 3+ sows, respectively. Alternatively, the requirement can be expressed as 14.3 g tTHR (11.8 g dTHR) per kilogram of litter gain.

Animal Nutritional Physiological Phenomena↗
PubMed2003

Modeling lactation curves and estimation of genetic parameters for first lactation test-day records of French Holstein cows.

Several functions were used to model the fixed part of the lactation curve and genetic parameters of milk test-day records to estimate using French Holstein data. Parametric curves (Legendre polynomials, Ali-Schaeffer curve, Wilmink curve), fixed classes curves (5-d classes), and regression splines were tested. The latter were appealing because they adjusted the data well, were relatively insensitive to outliers, were flexible, and resulted in smooth curves without requiring the estimation of a large number of parameters. Genetic parameters were estimated with an Average Information REML algorithm where the average information matrix and the first derivatives of the likelihood functions were pooled over 10 samples. This approach made it possible to handle larger data sets. The residual variance was modeled as a quadratic function of days in milk. Quartic Legendre polynomials were used to estimate (co)variances of random effects. The estimates were within the range of most other studies. The greatest genetic variance was in the middle of the lactation while residual and permanent environmental variances mostly decreased during the lactation. The resulting heritability ranged from 0.15 to 0.40. The genetic correlation between the extreme parts of the lactation was 0.35 but genetic correlations were higher than 0.90 for a large part of the lactation. The use of the pooling approach resulted in smaller standard errors for the genetic parameters when compared to those obtained with a single sample.

Animals↗
PubMed2004

Impact of early lactation somatic cell count in heifers on somatic cell counts over the first lactation.

The objective of this study was to estimate the impact of somatic cell count in early lactation (SCCel) from Belgian dairy heifers on test-day somatic cell count (SCC) in first lactation. Geometric mean SCCel [5 to 14 d in milk (DIM)] of the 14,766 available samples was 104,000 cells/mL, and decreased from 178,000 at 5 DIM to 74,000 cells/mL at 14 DIM. Proportion of SCCel >200,000 cells/mL was 27.5. Heifers calving in the period April-June had highest SCCel. In total, 117,496 monthly SCC were measured. A multilevel regression analysis revealed that an increase of the natural log-transformed SCCel (LnSCCel) by one unit on average resulted in an increase of test-day natural log-transformed SCC (LnSCC) by 0.22 unit. The impact of LnSCCel on LnSCC depended on when LnSCCel was measured; an elevated LnSCCel at 14 DIM was more consequential than an equally elevated LnSCCel at 5 DIM. The probability of having a test-day SCC >200,000 cells/mL during the first lactation, also increased with an increasing LnSCCel. The negative effect of an elevated LnSCCel was still present, although to a lesser extent, in heifers with a second test-day SCC <or=50,000 cells/mL. This study indicates that udder health problems in heifers in early lactation have a high prevalence and stresses that heifers should have a low SCCel, because an elevated SCCel will negatively influence test-day SCC during the whole first lactation.

Animals↗