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PubMed1993

Cytoplasmic oxytocin and vasopressin gene transcripts decline postpartum in the hypothalamus of the lactating rat.

Oxytocin (OT) and vasopressin (AVP) gene expression are enhanced in the rat hypothalamus in late gestation and during the second and third weeks of lactation. We report that during the first 3 postpartum days, OT and AVP cytoplasmic mRNAs in the supraoptic and paraventricular nuclei of lactating rats decreased dramatically, reaching less than one fifth of peak gestational levels by day 2 postpartum. Differences in the temporal pattern of OT and AVP expression were observed in the supraoptic and paraventricular nuclei from days 4-10 of lactation. We also compared OT and AVP cytoplasmic mRNAs isolated from the hypothalamus of day 3 lactating rats to cohorts that had litters removed at the time of parturition. Lactating rats had significantly lower OT and AVP cytoplasmic mRNA levels than their nonlactating cohorts. We further compared OT and AVP cytoplasmic mRNAs in the hypothalamus of day 12 lactating rats that had been ovariectomized or sham ovariectomized on day 3 of lactation. Ovariectomized day 12 lactating animals had significantly lower OT and AVP cytoplasmic mRNA levels than their intact cohorts. These data refute the hypothesis that lactation is characterized by persistently elevated hypothalamic cytoplasmic OT and AVP mRNAs produced as a result of continuous stimulation by suckling and suggest that ovarian steroids may exert a modulatory effect on hypothalamic OT and AVP expression during early lactation.

Animals↗
PubMed1997

Enhanced nonsaturable calcium transport in the jejunum of rats during lactation, but not during pregnancy.

The lactating (L) rat loses in excess of 100 mg of calcium (Ca) per day to milk at peak lactation. Most of the Ca must be provided by increased intestinal absorption. In an effort to examine adaptation of intestinal calcium absorption during lactation, nonsaturable absorption from the small intestine of rats was calculated from the disappearance of Ca from in situ ligated loops of jejunum during the last week of pregnancy and throughout lactation and weaning. Efficiency of absorption is reflected by the slope of the regression line of Ca absorbed on Ca introduced into the loop. Absorption of Ca in the jejunum was markedly enhanced starting at 5 days of lactation and for the remainder of lactation. Two days after weaning, the efficiency ofjejunal Ca absorption decreased to the nonmated (NM) control level, while the lactation-associated intestinal hypertrophy persisted beyond 2 days postweaning. The percentages of water and Ca absorbed were positively and significantly correlated in both L and NM rats. In contrast to Ca, magnesium (Mg) and strontium (Sr) transport from ligated loops were not enhanced during lactation. Fifty millimolar glucose in the test solution increased the absorption of both water and Ca, but not Mg, from jejunal loops of NM rats. Glucose increased Ca absorption in NM rats up to the level seen in L rats. Glucose did not increase Ca absorption further in L rats, perhaps because of the greater availability of glucose to the intestine during lactation. We conclude that in rats the efficiency of nonsaturable Ca absorption from the jejunum is significantly increased during well established lactation, but not during pregnancy. The underlying mechanism appears to be specific for Ca, may be dependent on glucose, and is unrelated to intestinal hypertrophy.

Animals↗
PubMed1997

Diagnostic value of lactate dehydrogenase isoenzyme pattern in pleural effusions.

Lactate dehydrogenase isoenzymes have been used to classify the nature of pleural effusion. Nevertheless, studies have reported conflicting results. The objective of this study was to evaluate the diagnostic value of lactate dehydrogenase isoenzymes in the analysis of pleural effusions. Pleural fluid samples obtained from three respective diagnostic groups: group I transudate (n = 23), group II parapneumonic effusion (n = 29) and group III malignant effusion or pleuritis carcinomatosa (n = 41) were evaluated. Total lactate dehydrogenase activity and lactate dehydrogenase (LDH) isoenzyme pattern were significantly different between transudative (group I) and exudative (group II and III) effusions. Group II and III showed a low percentage of LDH1 (p < 0.001), whereas the percentages of LDH4 (p < 0.001) and LDH5 (p < 0.001) were higher compared to group I. Moreover, in exudative effusions the percentage of LDH1 (p < 0.005), LDH4 (p < 0.005), as well as LDH5 (p < 0.005) were significantly different between parapneumonic and malignant effusions. In contrast to relative lactate dehydrogenase isoenzyme values, the absolute values of lactate dehydrogenase isoenzymes did not differ between group II and group III. Logistic regression analysis yielded a strong discrimination between group I and II+III, simultaneously using lactate dehydrogenase, glucose and protein as explanatory variables. Logistic regression analysis yielded only a weak discrimination between group II and III, simultaneously using lactate dehydrogenase, glucose and the absolute values of LDH2 and LDH4 as explanatory variables. In conclusion, the lactate dehydrogenase isoenzyme pattern differed between pleural effusions of transudative and exudative origin. However, including lactate dehydrogenase isoenzyme activities in the biochemical work-up of pleural effusions did not reveal an additional discriminatory value in the assessment of the classification of these effusions.

Aged↗
PubMed1984

Human maternal-fetal lactate relationships.

This study attempts to determine the major source of lactate in the normal and in the depressed human fetus, in order to assess the applicability of fetal blood lactate measurement for the evaluation of fetal stress during labor. We obtained umbilical arterial and venous blood samples at delivery in 132 liveborn infants, together with simultaneous maternal radial arterial samples. All samples were analyzed immediately for pH, blood gases, and lactate. In vigorous newborns (1-minute Apgar score greater than or equal to 7), umbilical arterial and venous lactate levels were lowest with elective cesarean section done before the onset of labor, higher with cesarean section performed during labor, and highest at the time of vaginal delivery (p less than 0.001, Tab. I). Fetal lactate levels were also significantly higher than maternal levels in vigorous newborns (p less than 0.01), the lactate difference between umbilical artery and maternal artery being lowest with elective cesarean section, higher with cesarean section performed during labor, and highest with vaginal delivery (p less than 0.02, Tab. II). Depressed newborns (1-minute Apgar score less than 7) had higher umbilical lactates and higher fetal-maternal lactate differences than vigorous newborns (p less than 0.01, Tab. III). Our results indicate that the blood lactate levels in both mother and fetus increase with labor and reach their highest values at the time of vaginal delivery. The lactate levels are highest in the umbilical artery, lower in the umbilical vein, and lowest in the maternal artery before the onset of labor.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗
PubMed1988

Effect of the suckling stimulus on daily LH surges induced by chronic oestrogen treatment in ovariectomized lactating rats.

Effects of the suckling stimulus on the daily LH surge induced by chronic oestrogen treatment were examined in ovariectomized lactating rats. Wistar-Imamichi strain rats were kept under 14 h light:10 h darkness (lights on at 05.00 h). Litter size was adjusted to eight on day 1 (day 0 = day of parturition) and ovariectomy performed on day 2. Lactating rats deprived of their litters on day 0 served as nonlactating controls. Silicone elastomer tubing filled with oestradiol was implanted on day 6 or 15. Blood samples were collected through an indwelling cannula at 10.00 and 17.00 h on each day after implantation to detect daily LH surges. Daily LH surges occurred in the late afternoon in both lactating and non-lactating rats implanted with oestradiol on day 6 or 15. The amplitude of daily LH surges in lactating rats implanted on day 6 declined much more rapidly than in non-lactating rats implanted on day 6, but no significant difference was found in the profile of the LH surge between lactating and non-lactating rats implanted on day 15. Pituitary LH contents just before the daily LH surge (12.00-12.30 h) 4 days after implantation in lactating rats implanted with oestradiol on day 6 were significantly less than those in nonlactating rats implanted with oestradiol on day 6 or 15 and in lactating rats implanted on day 15.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Studies on the role of TRH and corticosterone in the regulation of prolactin and thyrotrophin secretion during lactation.

This study describes the effects of litter size and acute suckling on the synthesis and release of hypothalamic TRH, as indirectly estimated by determination of hypothalamic prothyrotrophin-releasing hormone (proTRH) mRNA and median eminence TRH content. The effects of litter size (five or ten pups) were studied throughout lactation, while suckling-induced acute changes were analyzed on day 13 of lactation in dams with ten pups. In view of the enhanced adrenal activity during lactation and recent evidence that corticosteroids have negative effects on hypothalamic TRH, we also studied adrenalectomized (ADX) dams treated with corticosterone to maintain basal plasma corticosterone levels. In addition to an increased plasma level of prolactin (PRL), adrenal weight and plasma corticosterone increased, while plasma TSH, tri-iodothyronine (T3), thyroxine (T4) and free T4 (FT4) levels decreased during lactation. Litter size correlated positively with plasma PRL, adrenal weight and plasma corticosterone. No effect of litter size was observed on plasma T3, but rats with ten pups had lower plasma TSH, T4 and FT4 than rats with a five-pup litter. Compared with dioestrous rats, lactating rats showed an increased hypothalamic proTRH mRNA content on day 2, but not on days 8 and 15 of lactation. Median eminence TRH in lactating rats gradually increased until day 15 and decreased thereafter. Acute suckling, after a 6-h separation of mother and pups, rapidly increased plasma PRL and corticosterone in the mothers, but had no effects on plasma TSH and thyroid hormone levels. Hypothalamic proTRH mRNA increased twofold after 0.5 h of suckling, and then gradually returned to presuckling values after 6 h. Compared with sham-operated rats, corticosterone-substituted ADX rats with ten pups had increased plasma PRL and TSH, hypothalamic proTRH mRNA and pituitary TSH beta mRNA on day 15 of lactation. Moreover, while acute suckling did not enhance TSH release in sham-operated rats, it provoked not only PRL but also TSH release in corticosterone-substituted ADX dams. It is concluded that suckling exerts a rapid, positive effect on hypothalamic proTRH mRNA content. However, the concurrent enhanced adrenal activity has negative effects on hypothalamic proTRH gene expression resulting in a suppressed hypophysial-thyroid axis during lactation. While TRH appears to play a role in PRL release during the first days of lactation and during acute suckling, TRH seems not important in maintaining PRL secretion during continued suckling.

Adrenalectomy↗
PubMed2003

Increased 5'-iodothyronine deiodinase activity is a maternal adaptive mechanism in response to protein restriction during lactation.

We have shown that protein restriction during lactation is associated with higher levels of serum and milk tri-iodothyronine (T(3)) with lower serum thyroxine (T(4)), suggesting an increased T(4) to T(3) conversion. To investigate this hypothesis, the activity of type 1 (D1) and/or type 2 (D2) iodothyronine deiodinases was evaluated on days 4, 12 and 21 of lactation in several tIssues of dams fed an 8% protein-restricted (PR) diet and controls fed a 23% protein diet. Serum TSH, T(3) and T(4) were measured by radioimmunoassay. Deiodinase activity was determined by the release of (125)I from (125)I-reverse T(3), under specific conditions for D1 or D2. PR dams had a transitory reduction in liver D1 activity (P<0.05) on day 12, and a small increase in thyroid D1 on day 12 followed by a small decrease on day 21. However, thyroid D2 activity was higher than controls (P<0.05) during the whole of the lactation period. Mammary gland D1 and D2 activities were lower on day 4 of lactation in PR dams (P<0.05), and D2 was higher on day 21 (P<0.05). Potentially, a lower conversion of T(3) to di-iodothyronine in the mammary glands of PR dams at the beginning of lactation may serve to provide more T(3) through the milk. Brown adipose tIssue (BAT) D2 activity was higher (P<0.05) in PR dams during all periods of lactation. PR dams showed higher skeletal muscle D1 activity only at the end of lactation, but no changes in D2 activity. Higher pituitary D1 and D2 activities in the PR group (P<0.05) at the end of lactation could have contributed to the lower serum TSH. These data suggest that the higher thyroid and BAT D2 activity during the whole of lactation and skeletal muscle D1 activity at the end of lactation may contribute to the higher serum T(3) in PR dams.

Adaptation, Physiological↗
PubMed1996

In vitro effects of bicarbonate and bicarbonate-lactate buffered peritoneal dialysis solutions on mesothelial and neutrophil function.

The inclusion of bicarbonate in the formulation of peritoneal dialysis solutions may avoid the in vitro impairment of certain cell functions seen with acidic lactate-based fluids. The supranormal physiological levels of HCO3- and PCO2 inherent in such formulations may, however, not be biocompatible. This study compared the in vitro biocompatibility of a pH 5.2 lactate-based formulation with formulations containing either 40 mM lactate at pH 7.4, 38 mM HCO3- at pH 6.8 (PCO2 at approximately 240 mm Hg) or 7.4 (PCO2 at approximately 60 mm Hg), and 25 mM HCO3- plus 15 mM lactate at pH 6.8 (PCO2 at approximately 160 mm Hg) or 7.4 (PCO2 at approximately 40 mm Hg). Significant release of lactate dehydrogenase or decreases in ATP content by human peritoneal mesothelial cells (HPMC) and human peripheral polymorphonuclear leukocytes (PMN) after a 30-min exposure to each test solution was only seen with the pH 5.2 lactate-based fluid. The ATP content of HPMC exposed to this fluid returned to control levels after 30 min of recovery in M199 control medium but showed a trend toward decreasing ATP content at 240 min. Similarly, interleukin (IL)-1 beta-induced IL-6 synthesis by HPMC was also only significantly reduced by the pH 5.2 lactate solution. PMN chemiluminescence was unaffected by 30-min exposure to all test solutions except for the pH 5.2 lactate formulation. Staphylococcus epidermidis phagocytosis was reduced to between 46 to 57% of control with all test solutions except the pH 5.2 lactate solution, which further suppressed the chemiluminescence response to 17% of control. These data suggest that short exposure to supranormal physiological levels of HCO3- and PCO2 does not impair HPMC or PMN viability and function. Furthermore, neutral pH lactate-containing solutions show equivalent biocompatibility to bicarbonate-based ones.

Adenosine Triphosphate↗
PubMed1991

Influence of feeding Aspergillus oryzae fermentation extract on the milk yields, eating patterns, and body temperatures of lactating cows.

Trials were conducted to evaluate effects of a fermentation extract of Aspergillus oryzae (AO) on milk production and composition, diet digestibility, and rectal temperature changes in lactating dairy cows. Treatments were incorporated as a top dressing at the morning feeding and consisted of control (90 g/d of ground sorghum) or AO (3 g of culture + 87 g of ground sorghum daily). Twenty-four mid-lactation Holstein cows were paired for production in Lactation Trial 1 (LT-1). In Lactation Trial 2 (LT-2), 46 cows (20 primiparous and 26 multiparous) in early lactation were used. Trials lasted 12 wk. In LT-1, AO supplementation increased milk yields only at 2 (P less than .05) and 8 wk (P less than .10) of treatment. Rectal temperatures were lower (P less than .05) for cows fed AO for 4 of 10 readings made during summer. Supplementation of AO culture in LT-2 (early lactation cows) increased milk production and feed efficiency (P less than .05). Inner ear temperatures tended to be lower (P less than .11) for cows fed AO. Digestion trials, conducted at the end of lactation trials, used Cr2O3 as an indigestible marker. In Digestion Trial 1, digestibilities were not significantly (P greater than .10) affected by AO supplementation. However, in Digestion Trial 2, AO increased (P less than .05) digestibilities of DM, OM, CP, NDF, and ADF. Length and number of meals were not affected (P greater than .10) by feeding AO. In summary, milk yields, efficiency of milk production, and nutrient digestibilities were higher for early lactation cows fed a high-concentrate diet supplemented with 3 g of AO/d. Mid-lactation cows fed a lower-energy diet were less responsive to AO than early lactation cows, though similar trends were shown.

Analysis of Variance↗
PubMed1992

Lactation characteristics of nine breeds of cattle fed various quantities of dietary energy.

Milk yield data were collected by weigh-suckle-weigh procedures at approximately 14, 28, 56, 84, 112, 138, 156, 184, and 212 d postpartum for mature Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental cows over a 4-yr period. Individual cows were fed at one of four energy intake levels. Parameters characterizing lactation curves for 431 lactations from 179 cows were estimated by nonlinear regression. Differences due to breed, level of energy intake, and the two-factor interaction between breed and level of ME allowance for scale and shape parameters of lactation curves and derived estimates for time of peak lactation, yield at time of peak lactation, and for total yield for a 210-d lactation period were evaluated. Breed and energy intake level were significant sources of variation for all traits. Pooled over energy levels, daily yields at time of peak lactation of Braunvieh, Gelbvieh, and Pinzgauer were greater (P less than .05) than those of Angus, Charolais, Hereford, and Limousin. Simmental and Red Poll were intermediate. Total lactation yield of the Braunvieh exceeded (P less than .05) that of all other breeds with the exception of Gelbvieh. Hereford produced less milk than (P less than .05) the other breeds. The response in yields at time of peak lactation as energy allowances increased for Braunvieh, Charolis, Gelbvieh, Limousin, and Pinzgauer cows were linear and resulted in higher yields at this time. Linear increases in total 210-d yield and times of peak lactation were observed for all breeds with the exception of Hereford.

Analysis of Variance↗
PubMed1996

The influence of dietary salt level on water consumption, farrowing, and reproductive performance of lactating sows.

During two consecutive lactations using a switch-back design, 16 sows received a corn, cassava, barley, and soybean meal diet supplemented with either 8.5 or 1 g/kg of NaCl (.4% Na or .1% Na, respectively). The average daily water consumption during the 4-wk lactation period was greater (P < .01) for the sows fed the high-salt diet than for those fed the low-salt diet (13.9 vs 12.4 L, respectively). Urine production accounted for 27% of the water intake during lactation. This resulted in a difference during the entire lactation period of 42.2 L in water consumption (P = .07) and 11.4 L in urine production (P = .07). The Na and Cl concentrations of the urine for sows fed the high-salt diet were higher than for sows fed the low-salt diet (P < .05), but the K, Mg, P, and Ca concentrations were not influenced. The milk composition, measured at d 1, 13, and 27 of lactation, was relatively independent of the dietary salt level, except for the Cl concentration at d 1 after farrowing, which was higher (P < .05) for sows fed the high-salt diet. The moisture and ash content of the milk increased with the length of the lactation, irrespective of the diet. The increased ash content on d 13 and 27 of lactation was accounted for by the increased concentrations of P and Ca. There was no effect of dietary salt level on weight change of the sow or on the growth performance of the pigs. The interval from weaning to estrus (n = 13, t = 2.48, P = .029) was shorter for sows fed the high-salt diet than for sows fed the low-salt diet (6.2 +/- 1.0 and 12.6 +/- 3.1 d, respectively). More sows were unsuccessfully mated after receiving the low-salt diet during lactation. These results indicate that a low-salt diet for lactating sows results in lower water consumption, lower urine production, and lower Na and Cl concentrations in the urine. Milk composition, weight change of the sow, and growth performance of the pigs were not altered, but reproductive failures afterward may point to a salt deficiency during lactation.

Animals↗
PubMed1996

Characterization of feed intake patterns during lactation in commercial swine herds.

This study created and used a data-base containing 25,719 farrowing and 19,393 subsequent litter records abstracted from the PigCHAMP records of 30 commercial farms and daily feed intake records of 25,040 of these lactating sows. Each lactation feed record was categorized into one of six patterns: RAPID, rapid increase in feed intake following farrowing; MAJOR, major drop in feed intake during lactation; MINOR, minor drop; LLL, low feed intake throughout lactation; LHH, low feed intake during the first week then increasing for the remainder of lactation; and GRADUAL, gradual increase in feed intake throughout lactation. At the herd level, patterns RAPID, MAJOR, MINOR, LLL, LHH, and GRADUAL were observed in 22.8%, 32.9%, 27.8%, 1.0%, 8%, and 14.7% of sows, respectively. On a sow basis, across all feed intake records of all farms, patterns RAPID, MAJOR, MINOR, LLL, LHH, and GRADUAL were observed at frequencies of 17.8%, 38.3%, 25.8%, 1.2%, 1.5%, and 15.4%, respectively. Using logistic regression, the risk factors affecting the occurrence of MAJOR and MINOR patterns were lower parity, thicker backfat, higher room temperature, and greater feed intake during early lactation. Average daily feed intake and the day of peak intake were 5.2 (1.4 SD) kg/sow and 12.6 (4.6 SD) d after farrowing. Regression coefficients of factors affecting ADFI derived from multiple regression analyses were 247 g for parity, 9 g for weaning litter weight (kg), -13 g for room temperature (degree C), 62 g for lactation length (d), and -.4 g for energy density (kcal/kg). This study demonstrated substantial individual sow and farm variation in overall feed intake and pattern of feed intake during lactation. It also identified key risk factors (i.e., parity, lactation length, room temperature, weaning litter weights, energy density) for ADFI and pattern of feed intake on commercial farms.

Animal Husbandry↗
PubMed1998

Body composition at farrowing and nutrition during lactation affect the performance of primiparous sows: I. Voluntary feed intake, weight loss, and plasma metabolites.

We used 35 primiparous sows to investigate the link between body fatness at farrowing and voluntary feed intake (VFI) during lactation. Two groups of sows were fed differently throughout gestation (either 2.3 kg/d of a diet containing 5.8% CP and 14.6 MJ DE/kg as fed or 1.7 kg/d of a diet containing 15.6% CP and 14.5 MJ DE/kg as fed) so that they commenced lactation at a similar body weight (158 to 152 kg) but with different body compositions: either 340 (fat) or 280 (lean) g of body fat/kg BW (P < .001). During lactation, sows were offered either a low-protein diet (7.9% CP and 15.5 MJ DE/kg as fed) or a high-protein diet (19.0% CP and 15.6 MJ DE/kg as fed) on an ad libitum basis. During lactation, VFI was measured daily, and sow body weight and backfat were measured weekly. Blood samples were collected from sows on d 110 of gestation and d 14 and 28 of lactation, and plasma was analyzed for NEFA, glycerol, insulin, glucose, and beta-hydroxybutyrate. Fat sows ate 30% less than their lean counterparts during lactation (P < .001), which corresponded to a 70% higher concentration of NEFA in plasma (P = .01) and a 30% higher concentration of glycerol (P = .15). The VFI during the first 2 wk of lactation was affected only by body fatness and not by the protein content of the lactation diet. The dietary supply of protein influenced VFI during wk 3 and 4 of lactation, possibly by affecting milk production and hence the drive to consume feed. Weight loss, particularly lean tissue loss, was minimized by feeding the high-protein diet during lactation (P < .002).

3-Hydroxybutyric Acid↗
PubMed2002

Lactation curves of commercial ewes rearing lambs.

Three-hour milk production measurements determined by machine milking at 3-d intervals throughout a 63-d lactation period were used to describe lactation curves for crossbred ewes lambing at 1 and 2 yr of age and rearing single and twin lambs. Age of ewe, type of rearing, and day of lactation affected (P < 0.05) milk production. Over the 63-d lactation, average daily milk production was 2.56 and 2.63 kg, respectively, for 1- and 2-yr-old ewes rearing single lambs and 2.73 and 3.47 kg, respectively, for 1- and 2-yr-old ewes rearing twins. Milk production of 2-yr-old ewes rearing twin lambs peaked at 21 d of lactation, and that of 1- and 2-yr-old ewes rearing singles peaked between 27 and 30 d of lactation. The largest differences in the lactation curves among age and rearing ewe classes were found in early lactation. These differences were reduced by midlactation, and by late lactation, milk production for all ewes was similar. Diurnal variation in milk production by ewes was evaluated in an 8 x 8 Latin square design. Diurnal variation in milk yield measurements of eight mature ewes, each bearing and rearing twin lambs, was similar between d 21 and 24 of lactation. Time of milk production measurements within a day did not affect yield determinations. Extrapolation from 3-h production estimates to daily milk production is valid in determining a ewe's milk contribution in support of lamb growth.

Age Factors↗
PubMed2002

Appearance and disappearance of swainsonine in serum and milk of lactating ruminants with nursing young following a single dose exposure to swainsonine (locoweed; Oxytropis sericea).

A series of experiments were conducted to investigate the elimination of swainsonine in the milk of lactating ruminants following a single dose oral exposure to swainsonine (locoweed; Oxytropis sericea) and to assess subsequent subclinical effects on the mothers and their nursing young. In a preliminary experiment, lactating ewes were gavaged with locoweed providing 0.8 mg swainsonine/kg BW (n = 4; BW = 75.8 +/- 3.6 kg; lactation = d 45) and lactating cows were offered up to 2.0 mg swainsonine/kg BW free choice (n = 16; BW = 389.6 +/- 20.9 kg; lactation = d 90). Serum and milk were collected at h 0 (before treatment), 3, 6, 12, and 24 for ewes, and h 0 (before treatment), 6, 12, 18, and 24 for cows. Swainsonine was highest (P < 0.05) by h 6 in the serum and milk of ewes. Consumption of at least 0.61 mg swainsonine/kg BW induced consistent (> 0.025 microg/mL) appearance of swainsonine in cow serum and milk. In response to the results obtained in the preliminary experiment, a subsequent experiment utilizing lactating ewes (n = 13; BW = 74.8 +/- 6.4 kg; lactation = d 30) and cows (n = 13; BW = 460.8 +/- 51.9 kg; lactation = d 90) was conducted. Each lactating ruminant was gavaged with a locoweed extract to provide 0 (control), 0.2, or 0.8 mg swainsonine/kg BW and individually penned with her nursing young. Serum and milk from the mothers and serum from the nursing young were collected at h 0 (before treatment), 3, 6, 9, 12, 24 and 48 (an additional sample was obtained at h 72 for ewes and lambs). Serum and milk swainsonine was higher (P < 0.05) in the 0.8 mg treated groups and maximal (P < 0.05) concentrations occurred from h 3 to 6 for ewes and h 6 to 12 h for cows (P < 0.05). Rises in alkaline phosphatase activity indicated subclinical toxicity in the treated ewes (P < 0.05). Following a single dose oral exposure to 0.2 and 0.8 mg swainsonine/kg BW provided by a locoweed extract, swainsonine was detected in the serum and milk of lactating ewes and cows, and rises in serum alkaline phosphatase activity were observed in the ewes. Neither swainsonine nor changes in alkaline phosphatase activity was detected in the serum of the lambs and calves nursing the ewes and cows dosed with swainsonine.

Alkaline Phosphatase↗
PubMed2005

Factors associated with early and mid-to-late fetal loss in lactating and nonlactating Holstein cattle in a hot climate.

The purpose of this study was to evaluate associations of lactation, somatic cell count score (SCCS) at breeding, milk yield, lactation number, interval from calving to breeding (days open), number of times inseminated, and season of breeding on fetal loss for lactating Holstein females (both first-parity and multiparous cows) and nonlactating Holstein heifers in a hot climate. Females were palpated between d 40 and 50 of gestation and again at d 70 to 80 to determine pregnancy status. Early fetal loss was defined as a loss that occurred after d 40 to 50 but before d 70 to 80. Mid-to-late fetal loss represented losses after d 70 to 80 but before expected calving. Lactating females had higher early (P = 0.055) and mid-to-late fetal loss (P < 0.05) than nonlactating heifers. Those lactating females with increased days open experienced greater early (P < 0.05) and mid-to-late fetal loss (P = 0.055), whereas lactating females with an elevated SCCS encountered greater mid-to-late fetal loss (P < 0.01). Milk yield, lactation number, number of times inseminated, and season were not associated with early or mid-to-late fetal loss. For nonlactating heifers, there were no associations between number of times inseminated, season, or age at breeding on early or mid-to-late fetal loss. In conclusion, lactating females were more likely to suffer early and mid-to-late fetal loss than nonlactating heifers. Also, days open and SCCS at breeding were related to ability of lactating females to maintain pregnancy, but there were no relationships between fetal loss and milk yield, lactation number, number of times inseminated, or season.

Age Factors↗
PubMed1979

Effect of dietary lactic acid on rumen lactate metabolism and blood acid-base status of lambs switched from low to high concentrate diets.

Two experiments were conducted with ruminally fistulated wether lambs to determine the effect of lactic acid addition to a hay diet on rumen lactate metabolism, blood acid-base status and subsequent adaptation to a high concentrate diet. In Exp. 1, lambs were fed mature brome hay (H), H plus 5% (w/w) D,L lactic acid (H5L) or H plus 10% lactic acid (H10L) (three lambs per treatment) for 14 days (phase I) then switched to a 90% concentrate diet for 2 days (phase II). In Exp. 2, lambs were fed alfalfa-brome hay (H) (six lambs), H plus 2.5% lactic acid (H2.5L) (six lambs) or H plus 5% lactic acid (H5L) (four lambs) during phase I, then switched to a 70% concentrate diet (3 days) followed by a 90% concentrate diet (10 days) (phase II). During both experiments rumen fluid samples were taken periodically for pH and lactate analyses and in vitro L- or D-lactate disappearance (IVLD) studies. Blood samples were taken to measure acid-base status, serum lactate, and serum calcium, magnesium and phosphorus. Dietary lactic acid enhanced IVLD during phase I of both experiments. L and D isomer IVLD rates were similar and followed zero-order kinetics. In Exp. 2, IVLD increased rapidly during phase II in response to increased concentrate level in the diet; the enhanced rates of H2.5L and H5L lambs were sustained for the first 3 days of phase II. Blood data from both experiments indicated a deleterious effect of dietary lactic acid on blood acid-base balance; however, this treatment effect was not manifested in any symptoms of acute acidosis. There was a decrease (P less than .05) in serum calcium during phase II of both experiments. In Experiment 1, serum calcium increased linearly (P less than .05) in response to dietary lactic acid level. In Exp. 1, rumen fluid total lactate and L-lactate were lower (P less than .05) for H5L vs H lambs during phase II. However, all lambs in Exp. 1 experienced acute acidosis; four of the nine lambs subsequently died. There was evidence of acidosis in Exp. 2, but there were no clear treatment effects during phase II on rumen fluid pH or lactate, or feed intake. All lambs adapted to the high concentrate diets as evidenced by rumen lactate levels and feed intakes. In both experiments, the proportion of L-lactate in rumen fluid decreased from almost 100 to about 50% of total lactate by the end of phase II.

Acid-Base Equilibrium↗
PubMed2005

Evaluation of peritoneal fluid lactate as a marker of intestinal ischaemia in equine colic.

REASONS FOR PERFORMING STUDY: The most common cause of death as a direct result of colic is acute circulatory failure secondary to intestinal ischaemia. Early and accurate recognition of ischaemic bowel is essential to decrease complications and increase survival. Blood to peritoneal lactate values have been evaluated as a prognostic indicator, but lactate values characterised by type of lesion have not been reported. HYPOTHESIS: Plasma and peritoneal lactate values are higher in horses with intestinal ischaemia secondary to a strangulating obstruction (ISSO). METHODS: Venous blood and peritoneal fluid were collected sequentially from 20 clinically healthy horses and 189 horses admitted for colic during a one-year period. Blood gas, pH, electrolyte (K+, Na+, Ca++, Cl-), glucose and lactate values were determined for blood and peritoneal fluid samples; other values recorded for peritoneal fluid included gross appearance, total protein and nucleated cell count. Information regarding diagnosis, treatment and outcome was retrieved from the medical records. RESULTS: Peritoneal and plasma levels of lactate were lower in control compared to clinical cases. Horses with ISSO had a higher peritoneal lactate value (8.45 mmol/l) than those with nonstrangulating obstruction (2.09 mmo/l). Factors with the strongest correlations with the presence of ISSO were changes in the gross appearance of the peritoneal fluid and values of peritoneal fluid chloride, pH and log10 lactate. CONCLUSIONS: Analysis of peritoneal fluid gross appearance, pH, lactate and chloride can be used for diagnosis of ISSO. POTENTIAL RELEVANCE: Peritoneal fluid lactate is a better predictor of ISSO than blood lactate and may aid in early detection of catastrophic peritoneal lesions such as intestinal strangulation and rupture.

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