Plasma Ca Research Articles

Association of subclinical hypocalcemia dynamics with dry matter intake, milk yield, and blood minerals during the periparturient period

Subclinical hypocalcemia (SCH) affects many high-producing dairy cows in the postpartum period. Recent work has shown that cows experiencing prolonged or delayed SCH are at increased risk for disease and produce less milk than cows experiencing a transient reduction in or normal concentrations of plasma Ca following parturition. Our objective was to determine the association between different postpartum SCH dynamics with pre- and postpartum dry matter intake (DMI), milk yield, and blood mineral concentrations. Data were retrospectively collected from multiparous Holstein cows (n = 78), and cows were classified into 1 of 4 SCH groups based on mean blood total Ca (tCa) concentrations at 1 and 4 d in milk (DIM): normocalcemic (NC; [tCa] >1.95 mmol/L at 1 DIM and >2.2 mmol/L at 4 DIM, n = 28); transient SCH (tSCH; [tCa] ≤1.95 mmol/L at 1 DIM and >2.2 mmol/L at 4 DIM, n = 27); delayed SCH (dSCH; [tCa] >1.95 mmol/L at 1 DIM and ≤2.2 mmol/L at 4 DIM, n = 6); and persistent SCH (pSCH; [tCa] ≤1.95 mmol at 1 DIM and ≤2.2 mmol/L at 4 DIM, n = 17). Linear mixed models were created to analyze the change in pre- and postpartum DMI, milk yield, and blood mineral concentrations over time as well as differences between SCH groups. Prepartum intake was similar between groups, but the NC and tSCH cows consumed more feed than the pSCH or dSCH cows during the first 3 wk of lactation. The tSCH cows produced more milk than the other 3 groups during the first 6 wk of lactation. Postpartum blood tCa and Mg were different between SCH groups and were highest in the NC cows and lowest in the pSCH cows. Our results suggest that the high level of DMI consumed by the NC and tSCH cows in the postpartum period supported an appropriate homeostatic response to the increased Ca demands of lactation, allowing for higher milk yield compared with their counterparts experiencing delayed or prolonged episodes of SCH.

Data mining: Biological and temporal factors associated with blood parathyroid hormone, vitamin D, and calcium concentrations in the Southwestern Chinese population

BackgroundParathyroid hormone (PTH) and vitamin D plays a major role in calcium (Ca) homeostasis and bone turnover. The purpose of this study was to assess which factors (sex, age, time of blood sampling, season of the year, temperature and sunshine hours (SHH)) had the greatest impact on plasma PTH, 25-OH-VitD, and Ca levels, and then whether these effects were clinically acceptable in a large number of Southwestern Chinese subjects. MethodThe data was from West China Hospital Health Examination Center, Sichuan University from April 1, 2018 to June 30, 2019. A total of 18,664 physical examination subjects were included. PTH and 25-OH-VitD were measured by a Roche Cobas e 601, and Ca was measured by a Roche Cobas 8000. Linear regression models were used to assess correlations between PTH, 25-OH-VitD, Ca and the above factors. ResultsThe concentrations of serum PTH in females were significantly higher than those in males, while the 25-OH-VitD and Ca were opposite. The concentration of PTH in data collection decreased in summer and increased in spring. The concentration of 25-OH-VitD decreases in spring and increases in autumn. PTH concentrations were negatively correlated with last month temperature and SHH, while 25-OH-VitD were opposite. Linear regression showed that season may be the main factor affecting serum PTH and 25-OH-VitD levels, and these effects were not clinically acceptable. ConclusionIn order to avoid influencing clinicians' investigation of suspected hyperparathyroidism and hypovitaminosis, reference intervals for PTH, 25-OH-VitD, and Ca should be established, taking into account sex, age and the season.

Longitudinal analysis of cell-free mutated KRAS and CA 19\u20139 predicts survival following curative resection of pancreatic cancer

BackgroundNovel biomarkers and molecular monitoring tools hold potential to improve outcome for patients following resection of pancreatic ductal adenocarcinoma (PDAC). We hypothesized that the combined longitudinal analysis of mutated cell-free plasma KRAS (cfKRASmut) and CA 19–9 during adjuvant treatment and follow-up might more accurately predict disease course than hitherto available parameters.MethodsBetween 07/2015 and 10/2018, we collected 134 plasma samples from 25 patients after R0/R1-resection of PDAC during adjuvant chemotherapy and post-treatment surveillance at our institution. Highly sensitive discriminatory multi-target ddPCR assays were employed to screen plasma samples for cfKRASmut. cfKRASmut and CA 19–9 dynamics were correlated with recurrence-free survival (RFS) and overall survival (OS). Patients were followed-up until 01/2020.ResultsOut of 25 enrolled patients, 76% had undergone R0 resection and 48% of resected PDACs were pN0. 17/25 (68%) of patients underwent adjuvant chemotherapy. Median follow-up was 22.0 months, with 19 out of 25 (76%) patients relapsing during study period. Median RFS was 10.0 months, median OS was 22.0 months. Out of clinicopathologic variables, only postoperative CA 19–9 levels and administration of adjuvant chemotherapy correlated with survival endpoints. cfKRASmut. was detected in 12/25 (48%) of patients, and detection of high levels inversely correlated with survival endpoint. Integration of cfKRASmut and CA 19–9 levels outperformed either individual marker. cfKRASmut outperformed CA 19–9 as dynamic marker since increase during adjuvant chemotherapy and follow-up was highly predictive of early relapse and poor OS.ConclusionsIntegrated analysis of cfKRASmut and CA 19–9 levels is a promising approach for molecular monitoring of patients following resection of PDAC. Larger prospective studies are needed to further develop this approach and dissect each marker’s specific potential.

Assessing calcium availability from limestone sources through bone and blood status of chickens

Calcium (Cu) availability from limestone (procured from different cement factories) was assessed through bone and blood status of chickens using the completely randomized design. Five hundred and twenty five (525) straight run broiler chicks that were 28 days Of age (trial l), four hundred and twenty (420) broiler finishers that were 56 days of age (trial 2), and 210 layers that had been laying for six months (trial 3) were used in the study. Six limestone dietary treatments and a control accounted for the seven diets that were assessed Twelve birds per treatment and 4 per replicate that had their weights close to the mean of the pen were selected in the broiler trials (trials I and 2) and three birds per pen and nine per diet were selected in the layer trial (trial 3) for bone and blood samples analysis. Bone samples were analyzed for bone weight, bone length, ash weight, percentage ash, Ca and phosphorus contents of ash and blood samples were analyzed for plasma Ca and alkaline phosphates activity. Results showed similar influence of sources on bone weight, bone length, ash weight and percentage ash. Ca and P contents of ash were significantly (P<0.05) affected by limestone sources but generally. Limestone sources produced mean values that were equal to or than the control diet in the starter phase (trail 1). In the finisher phase (trial 2), only Ca content of ashy varied significantly where Jakura source produced the least mean value. The layer trial (trial 3) also produced mean values that were significant (P <0.05) for Ca content of ash with the Sokoto source producing the least mean value. Plasma Ca and alkaline phosphates enzyme activity attained published values for chickens. It was concluded based on the information from this study that the (h from tested limestone sources was generally available for chicken production.

Short-Term Intervention with Garlic-Based diets Modulates mRNA Expression of Calmodulin, Inositol-1,4,5-Trisphosphate Receptor-1, and Intracellular Adhesion Molecule in Cyclosporin-Induced Prehypertensive Wistar Rats

This study assessed the short term effect of Allium sativum-based diets on mRNA expression of Calmodulin (CaM), Inositol Trisphosphate receptor (IP3R) and Intracellular adhesion molecule (ICAM-1) in the heart and aorta of cyclosporin-induced prehypertensive rats. Plasma levels of Ca2+ and Tumor Necrosis Factor-alpha (TNF-alpha) were also determined. The experimental rats used for this study were randomly allocated into 7 groups (n=4): normotensive control rats (fed basal diet); untreated prehypertensive rats (fed basal diet); prehypertensive rats (fed 10% and 20% Allium sativum based diets respectively); normotensive rats (fed 10% and 20% Allium sativum based diets respectively); prehypertensive rats treated with 10mg/kg captopril respectively for 7 days. Induction of hypertension with cyclosporin caused significant increase (p < 0.05) in mRNA expression of CaM, IP3R and ICAM-1, accompanied by increased (p < 0.05) systolic and diastolic blood pressures, plasma Tumor Necrosis Factor-alpha (TNF-alpha) and Ca2+ levels. These effects were considerably reversed by Allium sativum-based diets fed to the prehypertensive rats. These findings provide evidence which suggest that CaM, IP3R, and ICAM-1 are also upregulated in prehypertension, but are modulated by short term dietary intervention with garlic.

Menthol stimulates calcium absorption in the rumen but not in the jejunum of sheep

Stimulation of Ca2+ absorption can counteract hypocalcemia at the onset of lactation. The plant bioactive lipid compound (PBLC) menthol is an agonist for nonselective cation channels of the transient receptor potential (TRP) family. It acutely stimulated Ca2+ absorption in ruminal epithelia of nonadapted animals ex vivo and caused higher plasma Ca2+ concentrations in cows and sheep in vivo. To elucidate the pathway by which menthol feeding increases plasma Ca2+ level, the present study aimed to investigate the long-term dose-dependent effects of dietary menthol-rich PBLC on Ca2+ absorption and mRNA abundances of TRP channels in both rumen and jejunum. Twenty-four growing Suffolk sheep were equally distributed to a Con, PBLC-L, and PBLC-H group, which received 0, 80, and 160 mg/d of a menthol-rich PBLC. After 4 wk, ruminal and jejunal epithelia were analyzed for mRNA abundances of TRPA1, TRPV3, TRPV5-6, and TRPM6-8 genes. The Ca2+ flux rates and electrophysiological properties of epithelia from rumen and mid-jejunum were measured in Ussing chambers in the presence and absence of mucosal Na+. Acute changes in Ca2+ flux rates were measured after mucosal application of 50 µM menthol. Ruminal epithelia had quantifiable transcripts of TRPV3 = TRPM6 >TRPM7 >TRPA1 with no difference among feeding groups. Jejunum had quantifiable transcripts of TRPM7 >TRPA1 ≥ TRPM6 ≥ TRPV6 >TRPV5, where TRPA1, TRPV5, and TRPV6 tended to decrease linearly with increasing PBLC dose. Absorptive net flux of Ca2+ was detected only in the rumen, whereas jejunum showed a high passive permeability to Ca2+. Net flux rates of Ca2+ in the rumen increased in a quadratic manner (highest in PBLC-L animals) and were systematically decreased with the omission of mucosal Na+. Short-circuit current increased in both PBLC feeding groups compared with Con only in the rumen. Acute application of menthol-stimulated mucosal-to-serosal and net Ca2+ flux rates only in ruminal epithelia with higher stimulation in PBLC-fed animals. We conclude that Ca2+ transport is mainly active and transcellular in the rumen. It most likely involves TRPV3 that can be stimulated by menthol. Pre-feeding of menthol-rich PBLC enhances ruminal Ca2+ absorption and sensitizes it to acute stimulation by menthol. By contrast, intestinal Ca2+ absorption is not sensitive to menthol stimulation. Menthol could be used as a tool to enhance ruminal Ca2+ absorption and to prevent hypocalcemia in dairy cows.

284 Effect of formulating diets based on a ratio between STTD Ca and STTD P and the inclusion of phytase on growth performance, plasma Ca and P, and bone ash of pigs from 11 to 130 kg

Abstract A 126-d experiment was conducted to test the hypothesis that the requirement for Ca expressed as a ratio between standardized total tract digestible (STTD) Ca and STTD P obtained in short-term experiments may be applied to pigs fed diets without or with microbial phytase from 11 to 130 kg. In a 5-phase program, 160 pigs (11.2 ± 1.8 kg) were randomly allotted to 32 pens and 4 corn-soybean meal diets in a 2 × 2 factorial design with 2 formulation strategies (total Ca or STTD Ca), and 2 phytase levels (0 or 500 units/kg) assuming phytase released 0.11% STTD P and 0.16% total Ca. The STTD Ca:STTD P ratios were 1.40:1, 1.35:1, 1.25:1, 1.18:1, and 1.10:1 for phases 1 to 5. At the conclusion of each phase, weights of pigs and feed left in feeders were recorded and a blood sample from 1 pig per pen was collected. At the end of phases 1 (d 24) and 5, the right femur of 1 pig per pen was collected. Data were analyzed as main effects of formulation strategy and phytase level and their interaction. Phase effect was analyzed by repeated measures. No interactions were observed and formulation strategy and phytase did not impact growth performance, bone ash, or plasma Ca and P on d 24 (Table 1). On d 126, an interaction (P &amp;lt; 0.05) between main effects was observed. Without phytase, pigs fed diets based on total Ca had greater bone ash than STTD Ca pigs, but with phytase, no differences were observed. A negative quadratic effect (P &amp;lt; 0.05) of phase for plasma Ca and P was observed. In conclusion, STTD Ca:STTD P ratios can be used in diet formulation for growing-finishing pigs without affecting growth performance. Phytase ameliorates bone resorption caused by low Ca in STTD Ca diets.

274 Determination of phosphorus requirement of lactating sows based on 24-hour urinary phosphorus excretion

Abstract The objective was to determine phosphorus (P) requirement of lactating sows using 24-hour urinary P excretion as the response criteria. The underlying assumption was that urinary P remains low and constant until the requirements are met then increases as P consumption increases. Thirty-six crossbred PIC Camborough sows (parity 3 to 7) were randomly assigned to 1 of 6 corn-soybean-meal diets with increasing dietary total P (tP) levels (0.40, 0.48, 0.56, 0.64, 0.72, and 0.80%) and a constant calcium (Ca) to tP ratio (1.25:1). Diets were fed from breeding until the end of lactation. Urine and blood samples were collected on days 4 and 18 of lactation and analyzed for P and Ca concentrations. Data were analyzed using MIXED and NLIN procedures of SAS. Phosphorus requirements were estimated using a broken-line regression model. Plasma Ca (ranging from 12.1 to 10.3 mg/dL) was not affected by dietary treatments, and was maintained within the normal physiological range on day 4 and 18 of lactation. Plasma P (ranging from 2.9 to 6.4 mg/dL) linearly increased (P &amp;lt; 0.05) with increasing dietary tP levels on day 4 and 18 of lactation. Only sows fed the 0.40% tP diet failed to maintain plasma P concentrations within the normal physiological range. Clinical signs of P and Ca deficiencies were not observed. Differences in sow and litter performance among treatments were not detected. A nonlinear response of urinary P excretion to dietary P intake was observed. Based on a broken-line linear model fit to 24-hour urinary P excretion, minimum tP requirements of sows at day 4 and 18 of lactation were 0.47 and 0.54%, respectively. In conclusion, 24-hour urine P excretion provided sensitive criteria for estimates of tP requirements in lactating sows. Efforts to adjust heteroscedasticity for animals fed dietary P above the estimated requirement need further evaluation.

Changes in physiological, haematological and biochemical parameters in police working dogs during a treadmill incremental exercise test

This study aimed to evaluate the physiological, haematological and biochemical changes during a treadmill incremental exercise test (IET). Animals were submitted to five stages of 6 min each, at 6, 7, 8, 9 and 10 mph, at an inclination of 5%. Blood samples were collected at rest (T0), immediately after exercise (T5) and after a 20 min rest period (T6), to determine complete blood count, urea, creatinine, creatine kinase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, total plasma protein, albumin, alkaline phosphatase (AP), cholesterol, triglycerides (Trig), Ca2+, Na+, K+ and Cl-. Blood lactate (BL), heart rate (HR), rectal temperature (RT) and glycaemia were measured at rest (T0), after each stage (T1-T5) and after the rest period (T6). Variations were recorded between T0 and T5 in red blood cells, haemoglobin, AP, Na+, K+ (P&lt;0.01), Trig (P&lt;0.05), Ca2+ and Cl- (P&lt;0.02). Differences were observed in BL at T5 (P&lt;0.02) and T6 (P&lt;0.02), RT at T2-T6 (P&lt;0.01), HR at T3-T5 (P&lt;0.01) and glycaemia at T2-T4 (P&lt;0.01) and T5 (P&lt;0.05). This study is a novel description of the shifts of physical fit police working dogs during this IET protocol.

Association of subclinical hypocalcemia dynamics on dry-matter intake, milk yield, and plasma mineral status during the periparturient period

Subclinical hypocalcemia (SCH) affects many high-producing dairy cows in the postpartum period. Recent work has shown that cows experiencing prolonged or delayed SCH are at increased risk for disease and produce less milk than cows experiencing a transient reduction or normal concentrations of plasma Ca. Our objective was to determine the association between the dynamics of SCH with pre- and postpartum dry matter intake (DMI), milk yield, and plasma mineral concentrations.

Phytate degradation, myo-inositol release, and utilization of phosphorus and calcium by two strains of laying hens in five production periods

The objective of this study was to compare 2 laying hen strains in 5 production periods regarding phytase activity, phytate (InsP6) degradation, and myo-inositol (MI) release in the digestive tract and phosphorus (P) and calcium (Ca) utilization. One offspring of 10 nonrelated roosters per strain (Lohmann Brown-classic (LB) or Lohmann LSL-classic (LSL)) was placed in one of 20 metabolic units in a completely randomized block design in week 8, 14, 22, 28, and 58 of life. All hens were fed the same corn and soybean meal–based diet at one time, but the diet composition was adjusted to the requirements in the respective period. For 4 consecutive days, excreta were collected quantitatively at 24-hour intervals. In week 10, 16, 24, 30, and 60, the blood plasma, digesta of crop, gizzard, jejunum, ileum, and ceca, and mucosa of the jejunum was collected. The concentration of inorganic P in the blood plasma was higher in LB than in LSL hens (P = 0.026). Plasma Ca concentrations increased with each period (P < 0.001) in both strains. In jejunum digesta, the MI concentration did not differ between strains, but InsP6 concentration was higher in LB than in LSL hens (P = 0.002) and the highest in week 30 and 60. Total phosphatase and phytase activities were higher in LB than in LSL hens (P ≤ 0.009). Period effects were also significant for these enzymes. Concentrations of some constituents of the cecal content were different between the strains. The MI concentration in the egg albumen and yolk was higher in LB than in LSL hens. Differences in InsP6- and MI-related metabolism of the 2 hen strains existed. These differences were partly dependent of the period. Especially, week 24 was a period of remarkable change of metabolism. Great differences also existed among individuals, making it worth to have a closer look at the metabolism of individuals in addition to evaluating treatment means. Further studies on metabolic, genetic, and microbiome level may help explain these differences.

Associations between lying behavior and activity and hypocalcemia in grazing dairy cows during the transition period

Hypocalcemia is a common metabolic disorder of transition dairy cows that is considered a gateway disease, increasing the risk of other health disorders and reducing cow performance. Clinical milk fever is associated with long periods of recumbency, and it is plausible that cows experiencing non-paretic hypocalcemia may spend more time lying; hence, lying behavior and activity measures may be useful in identifying at-risk cows. The objective of this study was to describe associations among blood calcium (Ca) status at calving and lying behavior and activity measures during the transition period in grazing dairy cows. Blood was sampled on the day of calving (d 0), and d 1, 2, 3, and 4 postcalving, and analyzed for total plasma Ca concentration. Twenty-four multiparous Holstein-Friesian and Holstein-Friesian × Jersey grazing dairy cows were classified, retrospectively, as clinically hypocalcemic (CLIN; blood Ca ≤ 1.4 mmol/L at 1 or more consecutive samplings within 48 h postcalving, but without parturient paresis). These cows were pair-matched (using milk production potential from their estimated breeding value for milk protein, mean body weight at wk -5 and -6 precalving, and, where possible, parity) with 24 cows classified as subclinically hypocalcemic (SUB; blood Ca > 1.4 and < 2.0 mmol/L at 2 consecutive samplings within 48 h postcalving), and 24 cows classified as normocalcemic (NORM; blood Ca ≥ 2.0 mmol/L at 3 consecutive samplings within 72 h postcalving). Lying behavior and activity were monitored using triaxial accelerometers from -21 to +35 d relative to calving. Data were summarized to calculate daily lying time (h/d), daily number of lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). On d 0, the CLIN group were less active and spent approximately 2.6 h longer lying than the SUB and NORM groups, particularly between 0200 and 1400 h. On d 0, the NORM group had fewer LB (16.3/d) than the SUB and CLIN groups (18.2 and 19.2/d, respectively). These differences in behavior were no longer detected 2 d postcalving, and no further differences were observed. The day before calving, the CLIN group spent 1.4 h longer lying down than did the SUB and NORM groups. Further, the relative change in steps from a precalving baseline period (d -14 to -7) until d 0 was positively, linearly associated with blood Ca concentration within 24 h postcalving. Future work should consider daily and temporal changes in behavior in individual cows to determine the potential for these measures to allow early detection of hypocalcemia.

Boron supplementation in peripartum Murrah buffaloes: The effect on calcium homeostasis, bone metabolism, endocrine and antioxidant status

BackgroundCalcium homeostasis and immuno-endocrine system undergoes drastic changes in peripartum dairy animals and failure to adapt these physiological changes causes major impact on animal health as well as productivity. Boron (B), a newer trace element, influences calcium (Ca), phosphorus (P) and magnesium (Mg) metabolism as well as immune system by manipulating several hormones or enzyme systems. Present study was conducted to determine the effect of dietary B supplementation on Ca homeostasis, bone metabolism, endocrine and antioxidant status in peripartum Murrah buffaloes. MethodsThirty advanced pregnant Murrah buffaloes (8th month pregnant) were allocated into three groups based on their most probable producing ability (MPPA) and parity (n = 10 in each group) viz. B0, B200 and B400 and supplemented with 0, 200 and 400 ppm of B in the form of boric acid. Blood samples were collected at periodic intervals (-45, -30, -21, -15, -7, 0, 7, 15, 30, 60, 90 and 120 day relative to expected date of calving) and analysed for minerals concentration, hormonal profile, bone health biomarkers and antioxidant enzymes. Results and conclusionBoron supplementation at 200 and 400 ppm increased (p < 0.05) plasma Ca, Mg and osteocalcin (OCN) concentration during postpartum stage. Higher (p < 0.05) levels of plasma 25-hydroxy vitamin D3 were observed in both B supplemented groups as compared to B unsupplemented group irrespective of physiological stages. Plasma parathyroid hormone (PTH) and cortisol levels were lower (p < 0.05) in both B supplemented groups than B unsupplemented group, especially during postpartum stage. Whereas, plasma ferric reducing total antioxidant power (FRAP) activity was found to be higher (p < 0.05) in B supplemented groups as compared to B unsupplemented group. Furthermore, antioxidant enzymes (erythrocytic superoxide dismutase; SOD, catalase, glutathione peroxidase; GPx), plasma level of total immunoglobulins (TIg), bone specific alkaline phosphatase (BALP) and tartrate resistant acid phosphatase (TRAP) remained unaffected by dietary B supplementation. Overall, it can be concluded that supplementation of B at 200 ppm in the diet of peripartum Murrah buffaloes helped to induce metabolic adaptations for improving Ca homeostasis, bone metabolism and antioxidant status without much additional benefits at higher level used in the present study.

Changes in Production Parameters, Egg Qualities, Fecal Volatile Fatty Acids, Nutrient Digestibility, and Plasma Parameters in Laying Hens Exposed to Ambient Temperature

The present study was undertaken to investigate the impact of heat stress on nutrient digestibility and tibia and reproductive traits, and changes in laying performance, egg qualities, fecal volatile fatty acids, and plasma parameters in laying hens. One-hundred twenty 52-week-old laying hens were raised in three temperature-controlled facilities with constant humidity (50% RH), either normal temperature (LT; 22°C) or heat stress considered being moderate (MT; 27°C) or severe (HT; 32°C) for 42 days. Feed intakes were consistently low (p < 0.01) in HT hens compared with those in LT or MT over the period of 42 days. Egg production kept markedly (p < 0.05) or numerically (p > 0.05) low in hens exposed to HT vs. LT or MT. Egg mass and egg weight were consistently low (p < 0.01) in hens exposed to HT compared with those raised under LT or MT. On the other hand, feed conversion ratio and frequency of dirty and cracked eggs were not significantly affected (p > 0.05) during the experimental period. HT-exposed hens consistently had lowered (p < 0.05) eggshell thickness and breaking strength, eggshell weight, and plasma Ca, P, and Mg levels compared with LT- or MT-treated hens. HT hens had lower (p < 0.01) relative oviduct weight and less number of large yellow follicles compared with those raised under LT or MT conditions at 42 days. Tibia traits measured at 42 days were not affected by any of heat treatments. Fecal volatile fatty acids tended to be higher in HT-exposed laying hens throughout the experiment. It was noted that digestibilities of neutral detergent fiber and dry matter were lowest (p < 0.05) in hens exposed to HT vs. LT or MT environments. Our study suggests that heat stress could lower laying performance, egg quality, and physiological parameters that are coupled with alterations in gut metabolites and mineral/lipid metabolism. The findings emerged from this study will help us design the nutritional and environmental strategies to mitigate the negative effect of heat stress on laying hens.

Calcium-Sensing Receptor and Regulation of WNK Kinases in the Kidney.

The kidney is essential for systemic calcium homeostasis. Urinary calcium excretion can be viewed as an integrative renal response to endocrine and local stimuli. The extracellular calcium-sensing receptor (CaSR) elicits a number of adaptive reactions to increased plasma Ca2+ levels including the control of parathyroid hormone release and regulation of the renal calcium handling. Calcium reabsorption in the distal nephron of the kidney is functionally coupled to sodium transport. Apart from Ca2+ transport systems, CaSR signaling affects relevant distal Na+-(K+)-2Cl− cotransporters, NKCC2 and NCC. NKCC2 and NCC are activated by a kinase cascade comprising with-no-lysine [K] kinases (WNKs) and two homologous Ste20-related kinases, SPAK and OSR1. Gain-of-function mutations within the WNK-SPAK/OSR1-NKCC2/NCC pathway lead to renal salt retention and hypertension, whereas loss-of-function mutations have been associated with salt-losing tubulopathies such as Bartter or Gitelman syndromes. A Bartter-like syndrome has been also described in patients carrying gain-of-function mutations in the CaSR gene. Recent work suggested that CaSR signals via the WNK-SPAK/OSR1 cascade to modulate salt reabsorption along the distal nephron. The review presented here summarizes the latest progress in understanding of functional interactions between CaSR and WNKs and their potential impact on the renal salt handling and blood pressure.

The effect of reducing dietary calcium in prestarter diets (0–4 D) on growth performance of broiler chickens, tibia characteristics, and calcium and phosphorus concentration in blood

During the incubation period, the Ca-to-P weight (mg/mg) ratio in the yolk increases from 0.26 on day 0 to 0.92 on day 17.5 and to 2.9 at hatch. Moreover, the absolute Ca content in the yolk increases by 41%, whereas P content decreases by 87%, from day 0 to the day of hatching. Thus, at hatch and during the first days after hatching, there are high reserves of Ca relative to P in the residual egg yolk, risking hypercalcemia and hypophosphatemia. A growth performance study was conducted to explore the effects of reducing dietary Ca content in the prestarter phase (0–4 D) on BW and bone mineral deposition during the first days after hatch and at market weight (day 37). Four prestarter (0–4 D) diets were formulated to have 0.4, 0.6, 0.8, and 1.0% Ca content. After the prestarter phase, all birds were fed with the same commercial diets based on a 3-phase feeding program (starter, grower, and finisher). Growth performance (BW, ADG, ADFI, and feed conversion ratio [FCR]) was monitored throughout the study, and blood and tibia bone samples were collected on specific days. On day 4, BW and ADG decreased with dietary Ca contents higher than 0.6% (P < 0.05), but there were no differences in BW on day 14 onward (P > 0.10). For the overall study (0–37 D), there were no differences in ADG and ADFI, but the FCR decreased with lower Ca contents (P < 0.05). On day 4, there were no differences in blood plasma Ca concentration, but P concentration increased in the group treated with diet containing 0.4% Ca compared with the groups treated with diets containing 0.6 and 0.8% Ca (P < 0.05). Tibia ash content decreased in the group treated with diet containing 0.4% Ca (P < 0.05) compared with all other treatments at the end of the prestarter phase. Tibia ash content and tibia breaking strength, on day 37, were not different among the treatments (P > 0.10). In conclusion, during the prestarter phase, BW increased with dietary Ca contents lower than 0.6%, most likely improving Ca–P balance; bone mineral deposition was reduced in this period. On feeding with a diet containing higher Ca content, bone mineral content was rapidly recovered.

Associations of Plasma Copper, Magnesium, and Calcium Levels with Blood Pressure in Children: a Cross-sectional Study.

Studies of the relationship of copper (Cu), magnesium (Mg), and calcium (Ca) levels with blood pressure in children are limited. This cross-sectional study included 443 children aged 6-9years from Guangzhou, China. Plasma concentrations of Cu, Mg, and Ca were measured by inductively coupled plasma mass spectrometry. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured with an electronic sphygmomanometer. Elevated SBP and DBP were defined as the 90th percentile or greater (age and sex specific) of reference values for Chinese children. Abnormal blood pressure (ABP) was defined as an elevated SBP and/or DBP. The plasma Cu concentration was positively correlated with blood pressure, body mass index (BMI), and the C-reactive protein (CRP) level, whereas the plasma Mg and Ca concentrations were negatively correlated with SBP. A higher Cu concentration (T3 vs. T1) was associated with a higher risk of ABP (odds ratio (OR) 2.55, 95% confidence interval (CI) 1.20 to 5.40). In contrast, children in the top tertiles of Mg (OR 0.42, 95% CI 0.18 to 0.98) and Ca (OR 0.28, 95% CI 0.11 to 0.70) concentrations showed lower risks of ABP than those in the bottom tertiles. Path analysis showed that the CRP levels and BMI mediated the associations between the Cu concentration and ABP. We found that higher plasma Mg and Ca concentrations were negatively related to blood pressure in children aged 6-9years. In contrast, a higher plasma Cu concentration was positively correlated with the risk of ABP, and the association was mediated by CRP and BMI.

Stimulatory effects of short-term calcitonin administration on plasma calcium, magnesium, phosphate, and glucose in juvenile Siberian sturgeon Acipenser baerii.

Calcitonin (CT) has a potential function in calcium (Ca) regulation, but there are conflicting observations in fishes. Because of the lack of calcified endoskeleton, sturgeons have low Ca circulating compared with teleost fish and the function of CT on Ca in sturgeon is very less understood. The purpose of this study was to investigate the impact of injection of salmon CT on plasma Ca, magnesium (Mg), phosphate (PHO), and glucose levels of juvenile Siberian sturgeon Acipenser baerii. Sixteen-month-old fish (429.6 ± 12.1g) were intraperitoneally injected with a single dose of CT (5μgkg-1 BW) and saline solution as a control group. Thereafter, blood sampling was performed at 0, 1, 2, 4, 6, 12, 24, and 48h after injection. CT produced marked increases in all variables measured. The highest levels of Ca (6.77 ± 0.53mgdL-1), Mg (9.79 ± 0.16mgdL-1) and PHO (1.74 ± 0.05mgdL-1) were recorded at 2h after CT injection and showed significant difference compared with control treatment (Ca 4.75 ± 0.12mgdL-1; Mg 5.47 ± 0.16mgdL-1 and PHO 1.23 ± 0.06mgdL-1). It also likely produced hyperglycemia. However, the differences with the controls were not statistically significant, possibly due to interference with the hyperglycemia induced by the stress of injection. Our results showed that the injection of 5μgkg-1 BW CT to Siberian sturgeon has an incremental effect on plasma Ca, Mg, and PHO. The increase in plasma Ca level indicated that CT has a potent hypercalcemic effect in sturgeon under laboratory condition, in contrast to the hypocalcemic effects reported for teleosts.

IMPACT OF PHYTASE SUPPLEMENTATION IN RESTRICTED CALCIUM AND PHOSPHORUS BROILER DIETS ON PERFORMANCE, BLOOD PARAMETERS AND BONE CHARACTERISTICS

Six weeks feeding trial using 210 one-day old unsexed Cobb 500 chicks was carried out to study the effects of addingphytase enzyme on growth performance, blood parametersand bone characteristics in broiler chicks. Three starter diets were used from 1 to 21 days; T100 {100% of Ca & non-phytate phosphorus NPP requirements (1.00% Ca and 0.50% NPP)}; T75{75% of Ca & NPP requirements (0.75% Ca and 0.38% NPP)} and T50 {50% of Ca & NPP requirements (0.51% Ca and 0.25% NPP)}. Three grower diets were used from 22 to 42 days; T100 {100% of Ca & NPP requirements (0.91% Ca and 0.46% NPP)}; T75{75% of Ca & NPP requirements( 0.68% Ca and 0.34% NPP)} and T50{50% of Ca & NPP requirements (0.45% Ca and 0.23% NPP)}. Seven dietary treatments were distributed according to diets fed consecutively during starter and grower phases as; (100/100) fed starter T100 then grower T100; (100/75) fed starter T100 then grower T75; (100/50) fed starter T100 then grower T50; (75/75) fed starter T75 then grower T75; (75/50) fed starter T75 then grower T50 and (50/50) fed starter T50 then grower T50.All diets added phytase enzyme (FTU 10000/Ton). Each treatment comprised of 30 chicks in 3 replicates of 10 chicks each. Results showed that live body weight and weight gain did not significantly affected by restricted Ca and NPP diets at starter period, where weight gain was significantly affected at grower period. Birds group received diet containing 100/75 with phytase (T3) gave the highest significant values for LBW and BWG, then 50/50 with phytase (T7) as compared with the other experimental groups during the grower and overall periods.Feed consumption and conversion ratio values were no significant differences among groups fed different dietary treatments during starter and grower phases. Plasma P concentrations was significantly affected however plasma Ca concentrations, GOT and GPT valueswere not significantly affected by the reduction of dietary Ca and NPPwith adding phytase. Percentages of tibia ash, Ca and P were significantly affected by dietary treatments. Supplementation of phytasehas a significant effect ontibia breaking strength, while supplementation of phytase hasn’t any effect on tibia Seedorindex.It is obvious that, the best performance was seen with (100/75) diet without any adverse effect on productive performance, blood parameters and most of tibia measurements and chemical composition.

Effect of subclinical and clinical hypocalcemia and dietary cation-anion difference on rumination activity in periparturient dairy cows

Rumination involves a complex series of muscle contractions that bring a bolus of ingesta to the mouth for further mastication before it is swallowed again. Healthy cows ruminate 8 to 9 h/d. Hypocalcemia is known to disrupt nerve and muscle function. Our hypothesis was that hypocalcemia in periparturient cows would reduce rumination activity. Twenty-six Holstein cows entering their third lactation or greater were fed a control diet [dietary cation-anion difference (DCAD) = +196 mEq/kg of dry matter (DM)] or a low DCAD diet supplemented with anions (DCAD = -9 mEq/kg of DM) prepartum. Periparturient plasma Ca concentration and rumination rate were determined. Four of 12 control cows developed clinical milk fever, necessitating intravenous Ca therapy. Rumination rate decreased in all cows around the time of calving. Rumination rate on the first and second day of lactation was highly correlated with the cow's plasma Ca concentration on the first day of lactation. In one of our statistical models, a normocalcemic cow was defined as a cow whose plasma Ca concentration remained above 2.00 mM. Cows were retrospectively classified as normocalcemic, subclinically hypocalcemic, or clinically hypocalcemic (milk fever). Only 4 cows were considered normocalcemic, and all had been fed the low DCAD diet. Normocalcemic cows spent more time ruminating on the first day after calving than subclinically hypocalcemic cows or cows with milk fever. Cows with milk fever had a lower rumination rate than normocalcemic cows through d 3 of lactation. Rumination activity in cows with milk fever was almost nondetectable in the hours before and after intravenous Ca treatment for an extended period, despite the return of muscle function that allowed the cows to stand and eructate following treatment. Other statistical models using different definitions of normocalcemia gave qualitatively similar results. Diet had a great effect on plasma Ca concentration and rumination rate. Even when cows with clinical milk fever were removed from the control cow data set, cows on the low DCAD diet had significantly greater plasma Ca concentrations in the first 36 h after calving and a higher rumination rate on d 1 of lactation (248 ± 26 min) than control cows (158 ± 32 min).