Preliminary Studies on the Concentration of Na+,K+-ATPase in Skeletal Muscle of Draught Cattle in Mozambique: Effect of Sex,Age and Training

The effect of training on the potential for work in draught cattle was assessed by measuring the Na⁺,K⁺-ATPase in the muscle cell membrane and the elevation in the concentration of K⁺ in plasma during exercise. Biopsies of the semitendinosus muscle and venous blood samples were taken from the cattle used for draught work in Mozambique. No differences were found in the plasma ion or Na⁺,K⁺-ATPase concentrations in samples taken from Nguni, Africander and Angoni breeds. There were no significant differences in plasma ions (Na⁺, K⁺ and Cl^–) or muscle Na⁺,K⁺-ATPase concentrations between the Angoni males and females, although the males showed an increase in Na⁺,K⁺-ATPase with age, while the females showed a decrease. The increase in males might be attributed to their higher level of activity in the herds than that of females. After a training period of 15 days, a significant increase in Na⁺,K⁺-ATPase concentration in semitendinosus muscle was found in Angoni cattle. In females, this was significant after 8 days of training (about 30%); in males after 15 days of training (about 16%). On day 15, there was a reduction in the elevation of plasma K⁺ during the 2 h of draught work, indicating an increased capacity of the Na⁺,K⁺ pumps to maintain the extracellular K⁺ concentration in working muscles and a possible delay in the moment of fatigue.     

Study of Sperm Concentration,Seminal Plasma Composition and their Physiological Correlation in the Persian Sturgeon,Acipenser persicus

The objectives of the present study were to determine ionic and organic composition of seminal plasma, sperm concentration and their relationships in the Persian sturgeon (Acipenser persicus). In this regard, ionic content (Na⁺, K⁺, Cl^?, Ca²⁺ and Mg²⁺) and organic content (total protein, glucose, cholesterol and triglyceride) along with sperm concentration were measured in 17 specimens of the Persian sturgeon. The seminal plasma contained 59.53 ± 2.56 mm /l sodium, 9.1 ± 1.42 mm chloride, 4.72 ± 0.3 mm potassium, 1.45 ± 0.075 mm calcium and 0.7 ± 0.072 mm magnesium. The following organic contents were found: total protein 0.11 ± 0.02 g/dl, glucose 22.18 ± 4.16 mg/dl, cholesterol 6.67 ± 1.04 mg/dl and triglyceride 15.2 ± 0.65 mg/dl. The mean sperm concentration was estimated to be 1.6 ± 0.12 (×10⁹ sperm/ml). A significant relationship was found between sperm concentration and K⁺ of seminal plasma (r = 0.533, p < 0.05). Significant correlations were observed between ionic contents: Na⁺ vs Cl^? (r = ?0.854, p < 0.01) and Mg²⁺ vs K⁺ (?0.583, p < 0.05). Also, level of triglyceride was negatively correlated with Mg²⁺ (r = ?0.503, p < 0.05). Presented data could be considered as a complementary study for developing special extenders and protectant solutions for improving artificial fertilization in this valuable species.     

Effects of dietary cation-anion balance on blood PH, acid base parameters, serum and urine mineral levels, and parathyroidhormone (PTH) in weanling horses.

This study demonstrated that the feeding of treatment diets with calculated dietary cation-anion balances (DCAB) of +370.43 (H) and -25.69 (L) did not have significant effects on blood pH, pCO₂, and HCO₃-. Serum Ca²⁺, P, Na⁺, and Cl^- as well as plasma PTH did not differ (P > .05) between the two treatment groups. Serum K⁺ was higher (P< .05) in horses fed diet H rather than diet L. The DCAB of the diet significantly affected urinary Ca²⁺, P, Na⁺, K⁺, and Cl^- excretion in the young growing horse. Urine Ca²⁺ and Cl- levels were higher (P < .01) in horses fed diet H versus diet L. Furthermore, levels of P, Na⁺, and K⁺ in the urine were higher (P < .01) in horses on diet H as opposed to diet L. Results of this study indicate that horses were able to maintain acid-base status regardless of diet. However, these data imply that growing horses consuming diets low in DCAB may be predisposed to abnormal bone mineralization due to the increase in calcium excretion which could lead to a weakening of the skeletal system.     

Effects of reducing dietary ([Na + K − [Cl + SO4]) on bone in dairy cows at parturition

The effects of feeding diets with different milliequivalents (mEq) of dietary ([Na⁺ + K⁺] − [Cl⁻ + SO₄⁼]) to dairy cows during the last seven weeks of pregnancy on bone morphology at parturition were studied. Nine monozygotic twin pairs of pregnant cows (five pairs of parity 1 or 2 and four pairs of parity 3 or more) were allocated to two diets which were formulated to provide either −4 mEq (anion diet) or +572·5 mEq (cation diet) of ([Na⁺ + K⁺] − [Cl⁻ + SO₄⁼]) kg⁻¹ dietary dry matter. Bone biopsies were taken from the tuber coxae between three and eight hours after parturition. The plasma concentrations of calcium and inorganic phosphorus, the total plasma alkaline phosphatase activity and the urinary hydroxyproline:creatinine ratio were not significantly affected by diet during the experimental period. In low parity (2 or less) cows the percentage trabecular bone volume, the percentage osteoclast surface and the mean number of osteoclasts per microscopic field (identified by Goldner staining) were lower on the anion diet than on the cation diet (P<0-02). In the high parity cows, the percentage osteoid volume (P<0·05) and the ratio of percentage osteoid volume to percentage osteoid surface (P<0·001) were greater in the cows fed the anion diet than in the cows fed the cation diet. The results show that reducing the mEq of dietary ([Na⁺ + K⁺] − [Cl⁻ + SO₄⁼]) to −4 mEq kg⁻¹ dietary dry matter affected some of the parameters of bone formation but did not enhance bone resorption.     

Composition of seminal plasma and ovarian fluid in Ide Leuciscus idus and Northern pike Esox lucius

Seminal plasma (SP) and ovarian fluid (OF) plays an important role as storage media to prevent the activation of gametes both in vivo and under artificial conditions. The objectives of this study were to quantify gamete biochemistry and explore correlations among quantitative characteristics of SP, OF and sperm performance traits of Ide Leuciscus idus and Northern pike Esox lucius. Generally, Na⁺, K⁺ and Cl^? were found to be the most dominating ions, although concentrations of K⁺ were higher in SP, while Na⁺ and Cl^? concentrations were higher in OF for both species. Several significant correlations among the biochemical properties such as total protein, glucose, osmolality, cholesterol, K⁺, Ca²⁺, Cl^? and Mg²⁺ were observed for SP and OF. Total protein content of Ide SP was positively correlated with sperm activity traits (r ≥ .89, p ≤ .05), while K⁺ concentration was negatively correlated with sperm traits (r ≥ ?.89, p ≤ .05). Moreover, Ca²⁺ concentration in Northern pike SP was positively correlated with the percentage of sperm motility (r = . 98, p < .01). In conclusion, these results can be used to better understand the biochemistry of SP and OF, improve methods for short‐ and long‐term storage of gametes and standardize fertilization protocols.     

Supplemented Morus nigra extract‐based medium associated with FSH enables the survival and growth of isolated ovine secondary ovarian follicles

The effects of Morus nigra ethanolic extract, without or with addition of supplements associated or not with FSH, on in vitro culture of ovine secondary follicles were evaluated. In experiment 1, isolated secondary follicles were cultured for 12 days in α‐MEM alone (control) or in different concentrations of M. nigra extract (MN 0.025; 0.05 or 0.1 mg/ml). In experiment 2, culture media were α‐MEM supplemented with BSA, insulin, transferrin, selenium, glutamine, hypoxanthine and ascorbic acid (α‐MEM⁺) or this medium associated with FSH (α‐MEM⁺ + FSH), or 0.1 mg/ml M. nigra without supplements (MN 0.1) or supplemented (MN 0.1⁺) without or with FSH (MN 0.1⁺ + FSH). In experiment 1, 0.1 mg/ml M. nigra showed the highest percentages (p < .05) of normal follicles and fully grown oocytes, besides a higher follicular diameter than α‐MEM and other M. nigra extract concentrations. Moreover, MN 0.1 showed lower (p < .05) glutathione (GSH) levels and similar (p > .05) mitochondrial activity compared to α‐MEM. In experiment 2, MN 0.1⁺ + FSH showed similar results (p > .05) to α‐MEM⁺ + FSH for all parameters evaluated, except for the daily growth rate, which was higher (p < .05) in MN 0.1⁺ + FSH. The GSH levels were higher in MEM⁺ than all treatments. In addition, oocytes from follicles cultured in MN 0.1⁺ + FSH showed ability to resume meiosis. In conclusion, M. nigra extract (0.1 mg/ml) added by supplements and FSH can be an efficient medium for ovine secondary follicle development.     

Blood buffering in sedentary miniature horses after administration of sodium bicarbonate in single doses of varying amounts

Blood acid-base and electrolyte status was studied in four sedentary Miniature Horses treated with 200, 300, 400 and 500 mg of sodium bicarbonate (NaHCO₃) per kg of body weight (BW). Arterial blood was collected before treatment with NaHC0₃ and each hour for 5 h after treatment. All treatments resulted in an increase in blood pH, bicarbonate (HCO₃⁻) concentration and base excess (BE) by 1 h post-dosage, which continued through the 5th hour (P < .05). Treatment with 200 mg NaHC0₃/kg BW resulted in less elevated blood HCO₃⁻ concentrations (P < .03) and BE values (P < .01) when compared to the other treatments. Following dosing with NaHCO₃, plasma Na⁺ concentrations increased among all treatments but declined to initial values by 3 h post-treatment. The 200 mg NaHCO₃/kg BW dosage resulted in the smallest increases in plasma Na⁺ concentrations (P < .03). Both plasma K⁺ and Ca⁺⁺ concentrations were lower (P < .05) among all treatment groups 1 h post-dosage but returned to initial values by 5 h and 3 h posttreatment, respectively, with no differences (P >.05) among treatments. All NaHCO₃ dosages increased blood buffering capacity as indicated by increased blood pH, HCO₃⁻ concentration and BE. Maximum blood pH, HCO⁻₃ concentration and BE was reached using a dosage of 300 mg NaHCO₃/kg BW. Also, all treatments altered the plasma electrolyte concentrations.     

Retracted: Determination of some blood and seminal plasma ions in the beluga,Huso huso (Linnaeus, 1758)

Blood and seminal plasma ionic parameters are essential for monitoring health status, detecting illnesses, fish stock conservation and development of artificial propagation methods via extender improvement. In this study, comparison of blood and seminal plasma ionic parameters in beluga, Huso huso (30–45 kg, 1–2 m, n = 10), was made. The results obtained show that Na⁺ (82.54 ± 5.46), Cl^‐ (15.95 ± 0.72) and K⁺ (3.57 ± 0.15) were predominant ions in the seminal plasma (as mm ). Blood ionic values (as mm ) were determined for Na⁺ (110.2 ± 1.26), K⁺ (3.77 ± 0.081), Cl^? (60.12 ± 1.5), Ca²⁺ (2.05 ± 0.35) and Mg²⁺ (1.9 ± 0.16). Results of the comparison between ionic parameters of seminal and blood plasma indicated that the concentrations of all parameters of blood plasma with the exception of K⁺ were significantly (p < 0.05) higher than those of seminal plasma.     

Effects of hypoxia and glucose-removal condition on muscle contraction of the smooth muscles of porcine urinary bladder

To elucidate the dependence of aerobic energy metabolism and utilization of glucose in contraction of urinary bladder smooth muscle, we investigated the changes in the reduced pyridine nucleotide (PNred) fluorescence, representing glycolysis activity, and determined the phosphocreatine (PCr) and ATP contents of the porcine urinary bladder during contractions induced by high K⁺ or carbachol (CCh) and with and without hypoxia (achieved by bubbling N₂ instead of O₂) or in a glucose-free condition. Hyperosmotic addition of 65 mM KCl (H-65K⁺) and 1 µM CCh induced a phasic contraction followed by a tonic contraction. A glucose-free physiological salt solution (PSS) did not change the subsequent contractile responses to H-65K⁺ and CCh. However, hypoxia significantly attenuated H-65K⁺- and CCh-induced contraction. H-65K⁺ and CCh induced a sustained increase in PNred fluorescence, representing glycolysis activity. Hypoxia enhanced H-65K⁺- and CCh-induced increases in PNred fluorescence, whereas glucose-free PSS decreased these increases, significantly. In the presence of H-65K⁺, hypoxia decreased the PCr and ATP contents; however, the glucose-free PSS did not change the PCr contents. In conclusion, we demonstrated that high K⁺- and CCh-induced contractions depend on aerobic metabolism and that an endogenous substrate may be utilized to maintain muscle contraction in a glucose-free PSS in the porcine urinary bladder.     

Changes in endocrine and immune responses of neonatal pigs exposed to a psychosocial stressor

The aim of the study was to determine the effects of a single social isolation (4 h) of piglets on immediate changes in stress hormones and immune responses at 7, 21 or 35 days of age. This social stressor caused an increase in plasma ACTH and cortisol concentrations and a decrease in plasma TNF-α. The percentage of CD8⁺ cells increased and the CD4⁺ cell percentage decreased, resulting in decreasing CD4⁺/CD8⁺ ratio. The observed changes were consistent for all days studied. Further, the isolation treatment resulted in diminished LPS-stimulated IL-1β and IL-10 production in whole-blood cultures. In isolated piglets, positive correlations were estimated between changes in percentage of CD8⁺ cells and cortisol, and negative ones between changes in plasma TNF-α and culture supernatant IL-1β with ACTH and cortisol. The data suggest that psychosocial stress in neonatal pigs induced immune alterations to maintain adaptive stability, but reflecting also negative emotions experienced by this treatment.     

Spermatozoa Concentration,Seminal Plasma Composition and Their Physiological Relationship in the Endangered Stellate Sturgeon (Acipenser stellatus) and Russian Sturgeon (Acipenser gueldenstaedtii )

Comparative studies of ionic composition, osmolality, protein concentration and pH of seminal plasma along with spermatozoa concentrations were carried out in stellate sturgeon, Acipenser stellatus, and Russian sturgeon, Acipenser gueldenstaedtii. Analysis of A. gueldenstaedtii sperm showed significantly higher concentrations of Na⁺ (34.58 ± 4.61 mm ), Ca²⁺ (0.35 ± 0.12 mm ), Mg²⁺ (0.70 ± 0.25 mm ), Cl^? (13.50 ± 4.04 mm ) and proteins (0.60 ± 0.29 mg/ml) in the seminal plasma than did seminal plasma of A. stellatus: Na⁺ (20.08 ± 10.75 mm ), Ca²⁺ (0.28 ± 0.06 mm ), Mg²⁺ (0.29 ± 0.05 mm ), Cl^? (7.50 ± 3.00 mm ) and 0.30 ± 0.11 mg/ml proteins. Significantly higher concentration of K⁺ (5.42 ± 1.06 mm ) was observed in A. stellatus compared to A. gueldenstaedtii K⁺ (2.29 ± 0.50 mm ). Concentration of Na⁺ was positively correlated with osmolality (r = 0.819), levels of Cl^? (r = 0.922) and Mg²⁺ (r = 0.727) and pH (r = 0.848). The concentration of Mg²⁺ was positively correlated with protein concentration (r = 0.774), Na⁺ (r = 0.727), Cl^? (r = 0.872) and Ca²⁺ (r = 0.801). A positive relationship was also found between concentration of K⁺ and spermatozoa concentration (r = 0.709). Results revealed strong inter‐species differences in several parameters. The data should be useful for artificial fertilization and for cryopreservation of sturgeon sperm.     

Some Effects of a Low Sodium Diet High in Potassium on the Renin-Angiotensin System and Plasma Electrolyte Concentrations in Normal Dogs

Pedersen, H.D., J. Koch, A.L. Jensen, K. Poulsen, A. Flagstad: Some effects of a low sodium diet high in potassium on the renin-angiotensin system and plasma electolyte concentrations in normal dogs. Acta vet. scand. 1994, 35, 133-140. - Eight normal male Beagle dogs received 0.7 mmol Na⁺/kg/day for 5 weeks and 4.0 mmol Na⁺/kg/day in one 3 week control period preceding and another similar period following the low sodium period. The dogs received 6.8 mmol K⁺/kg/day throughout the study.The median plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were higher in the low sodium period than in the following control period (0.67 versus 0.28 ng/ml/h, p < 0.0001) and (204 versus 31 pg/ml, p < 0.0001). PRA and PAC quickly stabilized on a new steady level in response to altered intake of sodium chloride. The angiotensin-converting enzyme (ACE) activity was not changed by the altered intake of sodium chloride.The plasma concentrations of sodium and chloride were increased during the low sodium period. This could be due to an indirect effect of the high potassium intake of the dogs. Potassium leads to an increased secretion of aldosterone and thereby to an increased retention of sodium and chloride in the kidney. The possible implications of a high potassium content in a low sodium diet are discussed.     

Inhibitory effects of SKF96365 on the activities of K+ channels in mouse small intestinal smooth muscle cells

In order to investigate the effects of {"type":"entrez-protein","attrs":{"text":"SKF96365","term_id":"1156357400","term_text":"SKF96365"}}SKF96365 (SKF), which is a non-selective cationic channel blocker, on K⁺ channel currents, we recorded currents through ATP sensitive K⁺ (I_KATP), voltage-gated K⁺ (I_Kv) and Ca²⁺ activated K⁺ channels (I_BK) in the absence and presence of SKF in single small intestinal myocytes of mice with patch-clamp techniques. SKF (10 µM) reversibly abolished I_KATP that was induced by cromakalim (10 µM), which is a selective ATP sensitive K⁺ channel opener. These inhibitory effects were induced in a concentration-dependent and voltage-independent manner. The 50% inhibitory concentration (IC₅₀) was 0.85 µM, which was obviously lower than that reported for the muscarinic cationic current. In addition, SKF (1 µM ≈ the IC₅₀ value in I_KATP suppression) reversibly inhibited the I_Kv that was induced by repetitive depolarizing pulses from −80 to 20 mV. However, the extent of the inhibitory effects was only ~30%. In contrast, SKF (1 µM) had no significant effects on spontaneous transient I_BK and caffeine-induced I_BK. These results indicated that SKF inhibited ATP sensitive K⁺ channels and voltage-gated K⁺ channels, with the ATP sensitive K⁺ channels being more sensitive than the voltage-gated K⁺ channels. These inhibitory effects on K⁺ channels should be considered when SKF is used as a cationic channel blocker.     

Flow-mediated K+ secretion in horses intoxicated with lolitrem B (perennial ryegrass staggers)

AIM: To investigate the effects of lolitrem B intoxication on renal K⁺ secretion in response to increased tubular flow rates.

METHODS: Results are derived from a repeated measure pilot study of seven horses fed non-perennial ryegrass feed for a week prior to exposing them to perennial ryegrass seed and hay that contained an average of 2 ppm lolitrem B. At the end of the control and treatment period frusemide (1 mg/kg I/V) was administered and serial fractional excretion of K⁺(FEK⁺) and fractional excretion of Na⁺(FENa⁺) calculated. Baseline concentration of aldosterone in plasma, serum K⁺concentration and feed K⁺ concentration were also compared.

RESULTS: Key findings included a reduced change in FEK⁺ from 0 to 15 minutes in response to frusemide administration (p=0.022, Wilcoxon signed-rank test) and a reduced baseline concentration of aldosterone in plasma (p=0.022, Wilcoxon signed-rank test) during the treatment period compared with the control.

CONCLUSIONS: Results suggest that lolitrem B intoxication reduced flow-mediated K⁺ secretion and interfered with aldosterone production or secretion. However, further investigation is required to validate these findings and to further elucidate the underlying pathophysiology.

CLINICAL RELEVANCE: Lolitrem B intoxication in horses may cause disruption to electrolyte handling in addition to neurological deficits.     

Genetic-diet interactions in the Hyperkalemic Periodic Paralysis syndrome in Quarter Horses fed varying amounts of potassium: I. Potassium and sodium balance, packed cell volume and plasma potassium and sodium concentrations

Six broodmares that were genetically tested to be heterozygous (H/N) and six broodmares that were tested to be homozygous negative (N/N) for Equine Hyperkalemic Periodic Paralysis (HYPP), that were descendents of the same stallion, were used in a replicated 3×3 Latin square experiment to determine the genetic-diet relationships in the HYPP syndrome.¹ The mares were fed rations consisting of 65% pelleted concentrate and 35% Coastal Bermuda grass hay that provided 1.1 (diet A), 1.9 (diet B) and 2.9% (diet C) potassium. The experimental periods were 14 days long, resulting in 28 meals per period. At meals 1 and 27, blood samples were taken every 30 minutes for 12 hours and every 10 minutes from 2 to 5 hours post-feeding. Total urine and fecal collections were made on the last 4 days of each period.Water, feed and fecal samples were analyzed for sodium and potassium content. Blood was analyzed for packed cell volume (PCV) and plasma potassium (K⁺) and sodium (Na⁺) concentrations.Apparent absorption of potassium was 99.8% across all diets, and potassium was excreted principally in the urine. More potassium was retained when the horses were fed diet B than diets A or C. Apparent absorption of sodium was 99.6% with no difference by diet. Neither potassium nor sodium balances were affected by HYPP status.There was no post-prandial pattern of plasma K⁺ concentration seen when the horses were fed the low potassium diet. When fed the higher potassium diets, they had greater plasma K⁺ values and exhibited a post-prandial peak at 2 to 5 hours after feeding. This peak occurred in all of the horses, meaning that plasma K⁺ cannot be used as a diagnostic aid for the presence of the HYPP mutation. By meal 27, some adaptation had occurred resulting in lower plasma K⁺ values when the horses were fed the higher potassium diets. The horses had increased plasma K⁺ concentrations throughout the post-prandial period while fed diet B compared to diet A, agreeing with the positive potassium balance seen in this experiment. The HYPP H/N horses had lower plasma Na⁺ concentrations in the early post-prandial hours and continuously greater PCV values than the HYPP N/N horses.     

Pharmacokinetics of magnesium and its effects on clinical variables following experimentally induced hypermagnesemia

The objectives of this study were to describe pharmacokinetic and pharmacodynamic changes as a result of a single intravenous administration of magnesium sulfate (MgSO₄) to healthy horses. MgSO₄ is a magnesium salt that has been used to calm horses in equestrian competition and is difficult to regulate because magnesium is an essential constituent of all mammals. Six healthy adult female horses were administered a single intravenous dose of MgSO₄ at 60 mg/kg of body weight over 5 min. Blood, urine, and cerebrospinal fluid (CSF) samples were collected, and cardiovascular parameters were monitored and echocardiograms performed at predetermined times. Noncompartmental pharmacokinetic analysis was applied to plasma concentrations of ionized magnesium (Mg²⁺). Objective data were analyzed using the Wilcoxon rank-sum test with p < .05 used as a determination for significance. Plasma concentrations of Mg²⁺ increased nearly fivefold, ionized calcium (Ca²⁺) decreased by nearly 10%, and the Ca²⁺ to Mg²⁺ ratio declined more than 3.5-fold and remained different than baseline until 24 hr (p < .05). Significant changes were seen with urinary fractional excretion of electrolytes, cardiovascular parameters, and echocardiographic measurements. No changes were detected in CSF electrolyte concentrations. The decrease in Ca²⁺ result of hypermagnesemia supports the interaction between these cations. Alterations detected in plasma electrolyte concentrations and urinary fractional excretion of electrolytes may serve as biomarkers for regulatory control for the nefarious administration of MgSO₄.     

Calcium homeostasis, acid–base balance, and health status in periparturient Holstein cows fed diets with low cation–anion difference

Forty multiparous Holstein dry cows on d 21 prepartum were randomly allocated to four blocks of 10 cows to examine the effects of reducing the dietary cation–anion difference (DCAD) on calcium homeostasis, acid–base balance, health status, and subsequent lactation performance. The reduced DCADs (Na + K − Cl − S, mEq/kg DM) of + 150,+ 50, − 50, and − 150 were obtained by addition of anionic salts. Reducing DCAD resulted in mild metabolic acidosis as indicated by the sharp decline in urinary pH, and minor reductions in blood pH and HCO₃⁻ concentration. Greater plasma calcium concentration was observed in cows fed diets of − 50 and − 150 DCAD (P < 0.05) than those on + 50 and + 150 DCAD diets. The nadir of plasma calcium level on the day of calving was lower (P < 0.05) than the highest level on d 14 prepartum (8.33 vs. 9.30 mg/dL). Composite colostrum calcium concentration was decreased (P < 0.05) with time on d 1 relative to d 2 postpartum (0.212 vs. 0.174%), and feeding of diet − 150 DCAD induced higher (P < 0.05) composite colostrum calcium content than other three DCAD diets. No case of milk fever occurred for any diets, but feeding the two negative DCAD diets reduced (P < 0.05) retained placenta incidence compared with diet of + 150 DCAD. Dry matter intake, milk yield and compositions of fat, protein, and lactose were non-significantly affected (P > 0.05) by dietary treatments. In conclusion, urinary pH is an effective indicator of extracellular fluid acid–base balance, and feeding negative DCAD in late gestation period is beneficial for dairy cows in blood calcium homeostasis and improvement of health status.     

Parturient hypocalcaemia in dairy cows: effects of dietary acidity on plasma minerals and calciotrophic hormones

Mature Friesian cows were given silage plus either an alkaline or an acidic concentrate mix during the last 28 days of pregnancy in two experiments. There were no significant differences in plasma calcium, phosphorus or magnesium concentrations before parturition but the blood ionised calcium and plasma chloride concentrations were significantly increased, together with a lower blood pH and acid-base excess in the cows on the acid diet. The mean 1,25-dihydroxyvitamin D concentrations tended to increase before parturition in the cows on the acid diet compared with the alkali diet in experiment 1 and were significantly higher in experiment 2. At parturition, the acid-fed cows had higher mean plasma calcium concentrations and significantly more of them had values >2·0 mmol litre⁻¹ than the alkali-fed groups, and the plasma 1,25-dihydroxyvitamin D and parathyroid hormone concentrations were related to these different plasma calcium concentrations. The acidic diets therefore appeared to prevent the onset of hypocalcaemia at parturition by increasing the plasma 1,25-dihydroxyvitamin D concentration before parturition.     

Experimental model of enterotoxigenic Escherichia coli infection in pigs: potential for an early recognition of colibacillosis by monitoring of behavior

The hypothesis that altered behavior is a sign for an early recognition of disease was tested. The experiment was conducted to evaluate the behavioral patterns of pigs in a model of postweaning colibacillosis. Twenty-five weaned pigs (from a herd that was previously found to be highly susceptible to F4⁺ Escherichia coli strains) were randomly assigned into 5 groups, kept in isolated pens under the controlled ambiental conditions. One day after weaning, the pigs from three groups were intragastrically inoculated (via orogastric tube) with either F4ac⁺ (1466 or 2407) or F4⁻ (1467) nonenterotoxigenic E. coli (non-ETEC) strains, respectively. The pigs from the fourth group were inoculated with F4ac⁺ ETEC strain M1823 and the remaining 5 pigs that received broth containing 1.2% sodium bicarbonate were kept as noninoculated controls. The pigs were examined daily and the frequency and duration of their behavioral patterns, such as eating, drinking, lying, standing, urinating, defecating, rooting and playing were monitored for 300 h during a period of 10 days. In this model, three conditions were also observed in F4-susceptible pigs: (1) acute fatal diarrheal disease; (2) moderate diarrhea and weight loss and (3) no diarrhea and weight loss. The incidence (both frequency and duration) of defecating was significantly higher (P<0.05) in pigs inoculated with F4ac⁺ ETEC strain M1823 as compared to that of noninoculated (control) pigs. Pigs inoculated with F4ac⁺ non-ETEC strain 1466 had a significantly lower frequency of eating (P<0.05) and frequency/duration of drinking (P<0.05) than did the controls. The 1466-inoculated pigs, had an increased diarrhea score, but frequency/duration of defecating was not significantly different. Pigs inoculated with F4ac⁺ non-ETEC strain 2407 spent more time in lying (P<0.05) than did noninoculated pigs. Conversely, the pigs that received F4⁻ non-ETEC strain 1467 laid shorter (P<0.05) and ate/drank less frequently (P<0.05) than the controls. It was concluded that the changed occurrence of defecating and eating in pigs that were inoculated with either F4ac⁺ ETEC (M1823) or non-ETEC (1466) strain, respectively, was consistent with the pending clinical disease, i.e. postweaning colibacillosis.     

Duration of feeding linseed diet influences peroxisome proliferator-activated receptor γ and tumor necrosis factor gene expression, and muscle mass of growing–finishing barrows

The aim of the study was to investigate the effect of duration of feeding linseed (rich in n-3 PUFA) on peroxisome proliferator-activated receptor γ (PPARγ) and tumor necrosis factor (TNF-α) gene expression, and muscle mass of growing–finishing barrows. Two isoenergetic and isonitrogenous diets were formulated, and one of which was the basal diet and another one was the linseed diet including linseed at the level of 10%. Twenty-four Landrace × Yorkshire barrows weighing 35 ± 3.7 kg were randomly assigned to four treatments with six individuals per treatment. Pigs in treatment 1 (T1) fed the control diet throughout the experimental period, while pigs in T2, T3 and T4 fed the control diet except for 30, 60, and 90 d prior to slaughter when the linseed diet were fed. The experiment was conducted for 90 days. The longissimus muscle mass and each muscle mass in the hind leg were weighted. PPARγ and TNF-α mRNA expression levels in muscle, spleen and adipose tissue, and plasma concentrations of TNF-α data were measured and analyzed. The results showed that the longissimus muscle mass, quadriceps femoris muscle mass and semitendinosus muscle mass increased linearly (P < 0.01) as prolonged the time of feeding linseed diet. The expression of PPARγ in longissimus muscle and spleen increased (P < 0.01) linearly as prolonged the time of feeding linseed diet, while the expression of PPARγ in adipose tissue were not affected (P = 0.095). Duration of linseed addition linearly decreased (P < 0.01) TNF-α gene expression levels in the longissimus dorsi muscle, adipose and spleen, and serum concentration of TNF-α as well. The expression levels of PPARγ negatively correlated with the expression of TNF-α in muscle (R² = 0.70, P < 0.001) and spleen (R²R² = 0.77, P < 0.001) respectively. Likewise, PPARγ expression level in spleen (R²R² = 0.59, P < 0.01) or muscle (R²R² = 0.52, P < 0.05) negative correlated with serum TNF-α concentration, while there were significant quadratic relation between muscular PPARγ (R²R² = 0.80, P < 0.01) or muscular TNF-α (R²R² = 0.87, P < 0.01) expression and the longissimus dorsi muscle mass. These data suggested that duration of feeding linseed diet lead to a linear decrease of TNF-α gene expression, which may increase the muscle mass in growing–finishing barrows, at least in part, through a PPARγ-dependent mechanism.