Serum concentrations of ionized calcium, vitamin D3, and parathyroid hormone in captive thick-billed parrots (Rhynchopsitta pachyrhyncha).

Serum collected from 68 thick-billed parrots (Rhynchopsitta pachyrhyncha) from 15 institutions was analyzed for ionized Ca (iCa), total Ca (tCa), P, total protein (TP), albumin (Alb), parathyroid hormone (PTH), and vitamin D3. Values were not distributed normally; 95% frequency intervals were as follows: iCa (0.82-1.3 mmol/L), tCa (1.37-2.09 mmol/L,), P (0.35-1.75 mmol/L), TP (21-39 g/L), Alb (9-13 g/L), PTH (0-65.68 pmol/L), and vitamin D3 (5.2-51 nmol/L). Sixty percent (+/-7.5%) of tCa was ionized. Female thick-billed parrots had significantly higher mean iCa (1.11 mmol/L, n = 22) than male thick-billed parrots (1.05 mmol/L, n = 32). tCa and iCa values in thick-billed parrots were lower than the reported values for other psittacine species. A significant positive linear relationship existed between Alb-TP and iCa-tCa ratios. A significant inverse linear relationship was also identified between the tCa-P ratio and PTH. These findings are consistent with known domestic avian Ca physiology.     

Hypocalcemia and hypovitaminosis D in dogs with induced endotoxemia

Background

Hypocalcemia is a documented electrolyte disturbance in people and animals with sepsis, but its mechanism is poorly understood.

Objective

To investigate mechanisms of hypocalcemia in dogs with experimentally induced endotoxemia.

Animals

Six healthy mixed breed dogs were included in this nonrandomized, placebo‐controlled, crossover study.

Methods

Dogs initially were injected with placebo (0.9% NaCl; 1 mL, IV) and then lipopolysaccharide (LPS; 2 μg/kg, IV) after a 5‐day washout period. Blood and urine samples were collected for measurement of serum total calcium (tCa), ionized calcium (iCa), total magnesium (tMg), ionized magnesium (iMg), parathyroid hormone (PTH), 25‐hydroxyvitamin D (vitamin D), venous blood gases, and fractional excretion (FE) of calcium.

Results

After LPS administration, body temperature increased and blood pressure decreased. Both iCa and tCa decreased (P < .01), but iMg was not significantly different between control and LPS treatments. PTH concentrations increased (P < .01) and vitamin D concentrations decreased (P < .01). Venous pH, bicarbonate, base excess, and blood glucose also decreased (P < .01). Urine tCa concentration was below the limit of detection for all dogs after LPS administration.

Conclusions

Hypocalcemia occurs during endotoxemia in dogs and is associated with hypovitaminosis D. Hypomagnesemia, hypoparathyroidism, alkalosis, and increased calciuresis are not associated with hypocalcemia in endotoxemic dogs.     

Restriction of vitamin A and D in beef cattle finishing diets on feedlot performance and adipose accretion

Feedlot producers often exceed NRC recommendations for vitamin A and D supplementation; however, increased concentrations of these vitamins have been shown to limit adipocyte differentiation in vitro. A feedlot trial was conducted using 168 Angus crossbred steers (BW = 284 ± 0.4 kg) allotted to 24 pens. The experiment had a 2 × 2 factorial arrangement of treatments: no supplemental vitamin A or D (NAND), 3,750 IU vitamin A/kg dietary DM with no supplemental vitamin D (SAND), no supplemental vitamin A and 1,860 IU vitamin D/kg dietary DM (NASD), and 3,750 IU and 1,860 IU vitamin A and D/ kg dietary DM (SASD), respectively. Serum, liver, and intramuscular and subcutaneous adipose tissue retinol concentrations were decreased in (P < 0.001) in cattle fed the no supplemental vitamin A diets (NAND and NASD combined) compared with those consuming supplemental vitamin A (SAND and SASD combined) diets. In addition, intramuscular retinol concentration was 38% less than in the subcutaneous depot. Serum 25(OH)D(3) concentrations were reduced (P < 0.001) during the first 70 d when cattle were fed no supplemental vitamin D diets (NAND and SAND combined); however, liver 25(OH)D(3) concentrations remained unchanged (P > 0.10) through d 184. Serum and liver 25(OH)D(3) concentrations increased (P < 0.001) with vitamin D supplementation (NASD and SASD combined). The DMI, ADG, G:F, and morbidity were not affected (P > 0.10) by dietary concentration of vitamin A or D. There were vitamin A and D interactions (P < 0.03) for backfat thickness and USDA Yield grade. Cattle fed the NAND diet had greater (P < 0.03) Yield grades than other treatments because of greater (P < 0.005) 12th rib backfat thickness in NAND steers than the NASD and SAND steers. Vitamin D concentrations were attenuated and minimal carcass adiposity responses to vitamin D supplementation were observed. Feeding a diet without supplemental vitamin A increased (P < 0.05) Quality grades and marbling scores and tended (P = 0.06) to increase ether extractable lipid of the LM. As retinol and 25(OH)D(3) concentrations in feedlot cattle declined as a result of a lack of dietary supplementation, adipose accretion increased, resulting in elevated Quality and Yield grades. Withdrawal of supplemental vitamin A, D, or both from the finishing diet of feedlot beef cattle had minimal impact carcass composition.     

Circadian rhythm of calciotropic hormones,serum calcium,phosphorus and magnesium during the shortest and longest days of the year in horses in New Zealand

A study was conducted to determine the circadian rhythms and trends of vitamin D metabolites including 25‐hydroxyvitamin D₃, 25‐hydroxyvitamin D₂, 1,25‐dihydroxyvitamin D and parathyroid hormone, in addition to serum calcium, phosphorus and magnesium concentrations in horses over 48 h on the shortest and longest days of the year in 2013. Five healthy adult horses (Equus caballus) were on a constant pasture feeding regimen, and blood samples were collected from each horse every 3 h over a 48‐h period, starting at 07:00 PM on day one and finishing at 07:00 PM on day three, for the measurement of calciotropic hormones and electrolytes. There was a significant difference between the serum concentration of calciotropic hormones, iCa, tCa, P and tMg between the shortest (winter) and longest (summer) days of the year in horses. Serum concentration of 25OHD₃ was very low and mostly undetectable. Serum iCa, 1,25(OH)₂D and PTH concentrations clearly showed a circadian rhythm on the longest days of the year and serum tCa, P and tMg concentrations showed a diurnal pattern on the longest days (summer) of the year. None of the analytes showed any circadian rhythm on the shortest days (winter) of the year. The result of this study could have significant relevance to equine athletes travelling to international equestrian competitions and facing a huge time and seasonal differences that might affect their ability to adjust their circadian rhythms to new time zones.     

Serum concentrations of calcium, phosphorus, magnesium and calciotropic hormones in donkeys

OBJECTIVE: To provide reference values for serum biochemical variables that are used for evaluation of mineral metabolism in donkeys and compare values with those in horses. ANIMALS: 18 donkeys and 18 horses. PROCEDURES: Total calcium (tCa), total magnesium (tMg), and inorganic phosphorus (P) concentrations were measured in serum samples via spectrophotometry. Ionized calcium (iCa) and magnesium (iMg) concentrations were quantified with selective electrodes. By use of a micropartition system, tCa and tMg were fractionated to separate protein-bound (pCa, pMg) and ultrafiltrable fractions. Complexed calcium (cCa) and magnesium (cMg) concentrations were calculated by substracting ionized fractions from ultrafiltrable fractions. Parathyroid hormone (PTH) and calcitriol (CTR) concentrations were measured via radioimmunoassay. RESULTS: Serum tCa concentration in donkeys (3.37 +/- 0.21 mmol/L) was composed of pCa (1.59 +/- 0.21 mmol/L [47.0 +/- 4.2%]), iCa (1.69 +/- 0.04 mmol/L [50.4 +/- 3.0%]), and cCa (0.09 +/- 0.08 mmol/L [2.6 +/- 2.9%]). Serum tMg concentration (1.00 +/- 0.08 mmol/L) was fractioned in pMg (0.23 +/- 0.08 mmol/L [23.4 +/- 8.1%]), iMg (0.59 +/- 0.04 mmol/L [58.8 +/- 5.1%]), and cMg (0.18 +/- 0.08 mmol/L [17.8 +/- 7.2%]). Serum concentrations of P (1.14 +/- 0.30 mmol/L), PTH (20.4 +/- 21.2 pg/mL), and CTR (13.4 +/- 5.9 pg/mL) were determined. CONCLUSIONS AND CLINICAL RELEVANCE: Serum variables of mineral metabolism in donkeys were within reference ranges for horses. However, when compared with horses, donkeys had higher iCa, cMg, and CTR and lower pMg and PTH concentrations.     

Effects of 25‐hydroxycholecalciferol with two D3 vitamin levels on production and immunity parameters in broiler chickens

This study was performed in Ross 308 chickens aged 1–21 days and aimed to evaluate whether the addition of 25‐hydroxycholecalciferol (25(OH)D₃) to broiler chicken diets affects their growth performance and immunity. A completely random 2 × 2 factorial arrangement was used with two levels of vitamin D₃ and the absence or presence of 25(OH)D₃, corresponding to four treatments based on sorghum + soya bean diets: (i) 200 IU of vitamin D₃/kg of feed (Diet 1) (NRC, 1994 ), (ii) Diet 1 + 69 μg of 25(OH)D₃/kg of feed (Diet 2), (iii) 5,000 IU of vitamin D₃/kg of feed (Diet 3) and (iv) Diet 3 + 69 μg of 25(OH)D₃/kg of feed (Diet 4). Each treatment was conducted with six replicates of 10 chickens each. Water and feed was supplied ad libitum. The results showed significantly increased growth and tibia ash (p < .05) in the birds fed 5,000, IU of vitamin D₃/kg + 25(OH)D₃. Additionally, the cellular immune response increased significantly (p < .05) in both treatments with added 25(OH)D_3. Based on the results obtained under the current test conditions, the addition of 25(OH)D₃ at a rate of 69 μg/kg to diets containing vitamin D₃ improved the cellular immune response and mineral deposition in the bones of broilers aged 1–21 days. Because these parameters are very important in modern poultry farming, these results indicate that supplementation with 25(OH)D₃ should improve broiler production.     

The effect of 25‐hydroxyvitamin D3 and phytase inclusion on pig performance,bone parameters and pork quality in finisher pigs

The objective of this study was to investigate the effects of supplementing both phytase and 25‐hydroxyvitamin D₃ (25‐OH ‐D?) on pig performance, nutrient digestibility, carcass characteristics, bone parameters and pork quality in finisher pigs. The experimental design was a 2 × 2 factorial comprising of four dietary treatments. One hundred and twenty pigs (60 male, 60 female) were blocked according to live weight and sex and allocated to the following dietary treatments: low P (4.81 g/kg) diet (basal) (T1); low P diet + phytase (T2); low P diet + 25‐OH ‐D? (T3) and low P diet + phytase + 25‐OH ‐D? (T4). Pigs supplemented with phytase had a lower average daily feed intake (ADFI ) (2.45 kg vs. 2.59 kg; p  < 0.05) and lower feed conversion ratio (FCR ) (2.74 kg/kg vs. 2.85 kg/kg; p  <  0.05) compared to pigs offered the nonphytase diets. Pigs offered phytase diets had a higher (p  <  0.05) coefficient of apparent total tract digestibility (CATTD ) of ash, phosphorous (P) and calcium (Ca) compared with pigs offered the nonphytase supplemented diets. Pigs offered the 25‐OH ‐D₃ diets had a higher CATTD of N and ash. Pigs offered the phytase diets had increased (p  <  0.05) bone DM , ash, Ca, P and density compared to the nonphytase diets. There was a significant interaction (p  <  0.05) between phytase and 25‐OH ‐D₃ on cook loss. Pigs offered 25‐OH ‐D₃ had increased cook loss over the basal diet; however, there was no effect on cook loss when phytase and 25‐OH ‐D₃ were offered in combination compared to the phytase only diet. Pigs offered 25‐OH ‐D₃ exhibited higher (p  <  0.05) Warner Bratzler shear force values and lower (p  <  0.05) pork lightness (L *) surface colorimeter values. In conclusion, there was no benefit to offering a combination of phytase and 25‐OH ‐D₃ on pig performance, bone parameters or pork quality.     

Fractionation of calcium and magnesium in equine serum

OBJECTIVE: To establish reference values for protein-bound, ionized, and weak-acid complexed fractions of calcium and magnesium in equine serum and determine stability of ionized calcium (iCa) and ionized magnesium (iMg) in serum samples kept under various storage conditions. ANIMALS: 28 clinically normal horses. PROCEDURE: Total calcium (tCa) and magnesium (tMg) in equine serum were fractionated by use of a micropartition system that allows separation of protein-bound calcium (pCa) and magnesium (pMg) and ultrafiltrable calcium (microCa) and magnesium (microMg) fractions. Serum concentrations of iCa and iMg were measured in the ultrafiltrate by use of selective electrodes. Serum concentration of complexed calcium (cCa) or magnesium (cMg) was calculated by subtracting iCa or iMg from microCa or microMg, respectively. RESULTS: Mean +/-SE serum tCa concentration was 3.26 +/- 0.06 mmol/L. Calcium fractions were as follows: pCa, 1.55 +/- 0.03 mmol/L (47.4 +/- 0.9%); iCa, 1.58 +/- 0.03 mmol/L (48.5 +/- 0.7%); and cCa, 0.13 +/- 0.02 mmol/L (4.1 +/- 0.9%). Serum tMg concentration was 0.99 +/- 0.04 mmol/L. Magnesium fractions were as follows: pMg, 0.33 +/- 0.04 mmol/L (33.3 +/- 4.2%); iMg, 0.57 +/- 0.02 mmol/L (57.6 +/- 1.7%); and cMg, 0.09 +/- 0.02 mmol/L (9.1 +/- 1.9%). Refrigeration (4 degrees C) did not affect iCa values, whereas iMg declined by 8% after 120 hours. Neither iCa nor iMg was affected by freezing (-20 degrees C). CONCLUSIONS AND CLINICAL RELEVANCE: In equine serum, iMg is less stable than iCa; thus, when serum samples are not going to be analyzed promptly, freezing may be preferable to refrigeration for storage.     

Serum 25‐hydroxyvitamin D concentrations in dogs – correlation with health and cancer risk

25‐hydroxyvitamin D (25(OH)D) is important in bone health as well as many diseases including cancer. Supplementation may increase responsiveness of cancer cells to chemotherapy. Serum 25(OH)D, intact parathyroid hormone (iPTH) and canine C‐reactive protein (c‐CRP) were measured in healthy dogs and dogs with haemoabdomen. Regression analysis determined optimal 25(OH)D concentrations. In healthy dogs (n = 282), mean iPTH concentrations correlated inversely (r² = 0.88, P < 0.001) to 25(OH)D concentrations. Variation in both iPTH and c‐CRP plateaued at 25(OH)D concentrations of 100–120 ng mL^?1. Haemoabdomen dogs (n = 63, 43 malignant and 20 benign) had 25(OH)D concentrations ranging from 19.4 to >150 ng mL^?1. Relative risk of cancer increased with decreasing 25(OH)D concentrations [RR = 3.9 for 25(OH)D below 40 ng mL^?1 (P = 0.0001)]. Serum 25(OH)D concentrations in dogs vary widely, and are influenced by dietary VitD content. Serum vitD measurement can identify dogs for which supplementation may improve health and response to cancer therapy.     

Effect of diet on serum 25-hydroxyvitamin D concentration in the short-beaked echidna (Tachyglossus aculeatus)

Background Elevated concentrations of 25‐hydroxyvitamin D (25(OH)‐D) were diagnosed in captive short‐beaked echidnas (Tachyglossus aculeatus) from three different zoological facilities within Australia. Results The mean serum 25(OH)‐D concentration in the wild echidnas was 24.7 nmol/L and was significantly higher in captive echidnas from all three facilities: Facility 1, mean 335.5 nmol/L (P < 0.001); Facility 2, mean 187.2 nmol/L (P = 0.003); Facility 3, mean 194 nmol/L (P = 0.005). Animals did not appear to have clinical manifestations of vitamin D toxicosis. The increased serum 25(OH)‐D concentration was attributed to excessive dietary intake and a reduction in the amount of vitamin D₃ in the diet of echidnas from Facility 1 resulted in a marked decrease in the serum 25(OH)‐D concentrations (mean 33 nmol/L). The reduction in serum 25(OH)‐D concentration was statistically significant (P = 0.002) and the resulting concentrations were similar to those of wild echidnas (P = 0.212). Conclusion It is not known what effect an elevated serum 25(OH)‐D concentration has on echidnas.     

Metabolic load in dairy cows kept in herbage‐based feeding systems and suitability of potential markers for compromised well‐being

Herbage feeding with only little input of concentrates plays an important role in milk production in grassland dominated countries like Switzerland. The objective was to investigate the effects of a solely herbage‐based diet and level of milk production on performance, and variables related to the metabolic, endocrine and inflammatory status to estimate the stress imposed on dairy cows. Twenty‐five multiparous Holstein cows were divided into a control (C+, n = 13) and a treatment group (C?, n = 12), according to their previous lactation yield (4679–10 808 kg) from week 3 ante partum until week 8 post‐partum (p.p.). While C+ received fresh herbage plus additional concentrate, no concentrate was fed to C? throughout the experiment. Within C+ and C?, the median of the preceding lactation yields (7752 kg) was used to split cows into a high (HYC+, HYC?)‐ and low‐yielding (LYC+, LYC?) groups. Throughout the study, HYC+ had a higher milk yield (35.9 kg/d) compared to the other subgroups (27.2–31.7 kg/d, p < 0.05). Plasma glucose (3.51 vs. 3.72 mmol/l) and IGF‐1 (66.0 vs. 78.9ng/mL) concentrations were lower in HYC?/LYC? compared to HYC+/LYC+ cows (p < 0.05). Plasma FFA and BHBA concentrations were dramatically elevated in HYC? (1.1 and 1.6 mmol/l) compared to all other subgroups (mean values: 0.5 and 0.6 mmol/l, p < 0.05). Saliva cortisol, plasma concentrations of serum amyloid A (SAA), haptoglobin (Hp), beta‐endorphin (BE) and activity of alkaline phosphatase (AP) were not different between C+ and C?. In conclusion, herbage‐fed high‐yielding cows without supplementary concentrate experienced a high metabolic load resulting in a reduced performance compared to cows of similar potential fed accordingly. Low‐yielding cows performed well without concentrate supplementation. Interestingly, the selected markers for inflammation and stress such as cortisol, Hp, SAA, BE and AP gave no indication for the metabolic load being translated into compromised well‐being.     

A comparison of total calcium,corrected calcium,and ionized calcium concentrations as indicators of calcium homeostasis among hypoalbuminemic dogs requiring intensive care

Objective – (1) To evaluate whether total calcium (tCa) correlates with ionized calcium (iCa) in hypoalbuminemic dogs; (2) to evaluate whether calcium adjusted for albumin (Alb), or total protein (TP), or both accurately predict iCa concentrations and hence can be used to monitor calcium homeostasis in critically ill hypoalbuminemic dogs; and (3) to evaluate factors associated with any potential discrepancy in calcium classification between corrected total and ionized values. Design – Prospective observational clinical study. Setting – Small animal intensive care unit in a veterinary medical teaching hospital. Animals – Twenty‐eight client‐owned dogs with hypoalbuminemia. Interventions – None. Measurements and Main Results – iCa was determined using ion‐specific electrode methodology, on heparinized plasma. The tCa concentration was adjusted for Alb and TP using published equations. In total 29% (8/28) of the hypoalbuminemic, critically ill dogs in this study were hypocalcemic at intensive care unit admission, as determined by iCa measurement. Corrected calcium values failed to accurately classify calcium status in 67.9% and 64.3% of cases, according to whether the Alb‐adjusted or TP‐adjusted values, respectively, were used. The sensitivity and specificity of the tCa to evaluate hypocalcemia was 100% and 47%, respectively. The sensitivity and specificity of the correction formulae were 37.5% and 79% for the Alb‐adjusted values and 37.5% and 74% for TP‐adjusted values. tCa overestimated the presence of hypocalcemia and underestimated the presence of normocalcemia, while corrected calcium values overestimated the presence of normocalcemia and underestimated the presence of hypocalcemia. Conclusions – Calcium homeostasis in hypoalbuminemic critically ill dogs should be evaluated by iCa concentrations rather than tCa or calcium adjusted for Alb or TP. Given that tCa has 100% sensitivity for detecting hypocalcemia in this population it is recommended that all hypoalbuminemic and critically ill patients with low tCa should be evaluated with an iCa measurement.     

Evaluation of total and ionized calcium status in dogs with blastomycosis: 38 cases (1997-2006)

OBJECTIVE: To determine blood ionized calcium (iCa) and serum total calcium (tCa) concentrations in dogs with blastomycosis and to evaluate whether serum tCa concentration, albumin-adjusted serum calcium concentration (AdjCa-Alb), and total protein-adjusted serum calcium concentration (AdjCa-TP) accurately predict iCa status. DESIGN: Retrospective case series. ANIMALS: 38 client-owned dogs with a cytologic diagnosis of blastomycosis. PROCEDURES: Dogs were classified as hypocalcemic, normocalcemic, or hypercalcemic on the basis of blood iCa concentration, serum tCa concentration, AdjCa-Alb, and AdjCa-TP; classification on the basis of serum tCa concentration, AdjCa-Alb, and AdjCa-TP was compared with blood iCa concentration. RESULTS: Except for 2 hypercalcemic dogs, all dogs had blood iCa concentrations within the reference interval. Use of serum tCa concentration overestimated hypocalcemia in 57.9% (22/38) of dogs and underestimated hypercalcemia in 1 dog. Use of AdjCa-Alb correctly reclassified all dogs as normocalcemic that were classified as hypocalcemic on the basis of serum tCa concentration, but failed to predict hypercalcemia in 1 dog. Use of AdjCa-TP correctly reclassified all but 2 dogs as normocalcemic that were classified as hypocalcemic on the basis of serum tCa concentration, and failed to predict hypercalcemia in 1 dog. No correlation was found between blood iCa concentration and serum concentrations of tCa, total protein, and albumin; AdjCa-Alb; or AdjCa-TP. CONCLUSIONS AND CLINICAL RELEVANCE: High blood iCa concentration was uncommon in dogs with blastomycosis. Hypoalbuminemia contributed to a low serum tCa concentration despite a blood iCa concentration within reference limits. The use of serum tCa concentration, AdjCa-Alb, and AdjCa-TP may fail to identify a small number of dogs with high blood iCa concentrations.     

ORIGINAL ARTICLE: Effect of the level of cholecalciferol supplementation of broiler diets on the performance and tibial dyschondroplasia

A study was conducted to evaluate four different cholecalciferol levels (NRC; modified), using diets supplemented with 200 (control), 1500, 2500 or 3500 IU/kg of cholecalciferol (VIT‐D3). Each treatment was assigned to 3 pens of 17 broiler chicks of a commercial strain grown in an open‐sided house with sidewall curtains. At 21and 42 days, BW and feed conversion (FCR) were determined. At 42 days, five birds per pen were slaughtered to evaluate tibia and toe ash of the right leg, and incidence and severity of tibial dyschondroplasia (TD) of the left tibia and also measured dressing percentage and breast meat yield. Serum calcium and phosphorus concentrations were also determined. Haemagglutination inhibition antibody titre against Newcastle disease virus and lymphoid organs weight/body weight ratio were also determined. At both 21 and 42 days, the BW of birds fed 1500 IU/kg to 3500 IU/kg of VIT‐D3 was significantly greater than birds fed 200 IU/kg. Similarly, better FCR was observed in birds those fed diets of high level of VIT‐D3. No significant difference was observed for mortality at any age. Better dressing percentage and breast meat yield were noted in birds fed diets containing 2500 or 3500 IU/kg VIT‐D3. Both tibia and toe ash contents were increased (p < 0.05) progressively with increased concentrations of cholecalciferol in feed. The incidence of TD (percentage of birds having TD scores greater than zero) was significantly (p < 0.05) influenced by level of 3500 IU VIT‐D3/kg at 42 days. The severity of TD in birds fed diets containing 200 IU/kg VIT‐D3 was apparently higher than birds fed diets with higher levels of VIT‐D3. Concentrations of calcium and phosphorus minerals in the serum increased progressively with the high level of VIT‐D3 supplementation to birds at both 21 and 42 days of age. Feeding levels of 1500 or 3500 IU of vitamin D3 did positively affect the immune system within the parameters measured. It may be concluded that performance, bone mineralization, blood chemistry and immunity against disease in broilers could be maintained when supplementing high level of VIT‐D3 incorporated in broiler diets.     

维生素D对蛋雏鸭生长性能及免疫功能的影响

试验选取1日龄健康、体重相近的金定蛋雏鸭180只,随机分为5个处理组,每个处理6个重复,每个重复6只试鸭。采用玉米-豆粕型基础饲粮,Ⅰ组试验鸭饲喂基础饲粮,Ⅱ～Ⅴ组分别饲喂在基础饲粮中添加110、220、550、1000 IU/kg维生素D的试验饲粮,试验期4周。旨在研究不同维生素D添加水平对1～28日龄蛋雏鸭生长性能及免疫功能的影响,以探讨维生素D的适宜添加量。结果表明,添加550 IU/kg维生素D能显著提高蛋雏鸭平均日增重、降低料重比(P<0.05),显著提高IgA、IgG、T3、T4含量(P<0.05),并显著降低Cort含量(P<0.05)。由此可见,在玉米-豆粕型基础饲粮中添加适量的维生素D可提高蛋雏鸭生长性能及免疫功能。通过二次回归模型分析,估测蛋雏鸭日粮中维生素D的适宜添加量为523.1～560.6 IU/kg。     

A comparison of UVb compact lamps in enabling cutaneous vitamin D synthesis in growing bearded dragons

The effect of exposure to different UVb compact lamps on the vitamin D status of growing bearded dragons (Pogona vitticeps) was studied. Forty‐two newly hatched bearded dragons (<24 h old) were allocated to six treatment groups (n = 7 per group). Five groups were exposed to different UVb compact lamps for two hours per day, with a control group not exposed to UVb radiation. At 120 days of age, blood samples were obtained and concentrations of 25(OH)D₃, Ca, P and uric acid were determined. In addition, plasma 25(OH)D₃ concentration was determined in free‐living adult bearded dragons to provide a reference level. Only one treatment resulted in elevated levels of 25(OH)D₃ compared to the control group (41.0 ± 12.85 vs. 2.0 ± 0.0 nmol/L). All UVb‐exposed groups had low 25(OH)D₃ plasma levels compared to earlier studies on captive bearded dragons as well as in comparison with the free‐living adult bearded dragons (409 ± 56 nmol/L). Spectral analysis indicated that all treatment lamps emitted UVb wavelengths effective for some cutaneous vitamin D synthesis. None of these lamps, under this regime, appeared to have provided a sufficient UVb dose to enable synthesis of plasma 25(OH)D₃ levels similar to those of free‐living bearded dragons in their native habitat.     

Effect of maternal canthaxanthin and 25‐hydroxycholecalciferol supplementation on the performance of ducklings under two different vitamin regimens

This study investigated the effects of maternal canthaxanthin (CX, 6 mg/kg) and 25‐hydroxycholecalciferol (25‐OH‐D₃, 0.069 mg/kg) supplementation on the performance of Cherry Valley ducklings under two different vitamin regimens. A total of 780 duck breeder females and 156 males were randomly allotted to two diets with or without the addition of the mixture of CX and 25‐OH‐D₃ (CX+25‐OH‐D₃) for 32 weeks. Ducklings (males and females separately) hatched from eggs laid at 24 weeks of the duck breeder trial were fed with a NRC vitamin regimen, and ducklings (males and females separately) hatched from eggs laid at 32 weeks of the duck breeder trial were fed with a HIGH vitamin regimen (had higher levels of all vitamins except biotin than NRC vitamin regimen), for 14 days. The results showed that, maternal CX+25‐OH‐D₃ supplementation increased the shank pigmentation for 7‐days post hatch in ducklings under a NRC vitamin regimen, and for 14‐days post hatch in ducklings under a HIGH vitamin regimen. Growth performance, antioxidant status and serum phosphorus of ducklings under a NRC vitamin regimen were increased by maternal CX+25‐OH‐D₃ supplementation; however, these positive effects were not observed in ducklings under a HIGH vitamin regimen. Males revealed increased growth performance in ducklings under both NRC and HIGH vitamin regimens. Sexual differences in shank pigmentation, antioxidant status, tibia strength and serum phosphorus were not consistent as they were dependent on maternal CX+25‐OH‐D₃ status or dietary vitamin regimens. Data suggest that maternal CX+25‐OH‐D₃ supplementation is important for starter ducklings under a NRC vitamin regimen, but not HIGH vitamin regimen.     

Effect of additional vitamin E and zinc supplementation on immunological changes in peripartum Sahiwal cows

This study was conducted to exploit ameliorative effect of additional vitamin E and/or zinc supplementation on immune response of peripartum Sahiwal cows. Thirty‐two pregnant dry Sahiwal cows were blocked into four treatment groups (n = 8), namely control, zinc (Zn), vitamin E (Vit E) and zinc + vitamin E (Zn + Vit E). Feeding regimen was same in all the groups except that the Sahiwal cows in the zinc‐, vitamin E‐ and zinc + vitamin E‐fed groups were additionally supplemented with 60 mg Zn/kg DM, 1000 IU vitamin E and 60 mg/kg + 1000 IU Zn + vitamin E, respectively, from day 60 pre‐partum to day 90 post‐partum. Blood samples were collected on days ?60, ?45, ?30, ?15, ?7, ?3, 0, 3, 7, 15, 30, 45, 60, 90 and 120 with respect to day of parturition and analysed for total immunoglobulin (TIG), immunoglobulin G (IgG), interleukin‐2 (IL‐2), vitamin E (Vit E) and zinc (Zn) status. Before calving, cows showed a decrease in plasma TIG, IgG, IL‐2, Vit E and Zn levels. However, increased levels of plasma TIG, IgG, IL‐2, Vit E and Zn were observed after calving. After calving, Sahiwal cows supplemented with Zn + Vit E had higher plasma TIG, IgG and IL‐2 in comparison with cows of control and Zn + Vit E‐fed groups. In the present study, plasma vitamin E level was higher in Vit E‐fed and Zn + Vit E‐fed cows; however, zinc level was higher in Zn‐ and Zn + Vit E‐supplemented cows. In conclusion, a reduced immune response during peripartum period in Sahiwal cows was ameliorated by dietary vitamin E and zinc supplementation.     

Factors associated with low vitamin D status of Australian alpacas

Objective To investigate factors associated with low vitamin D status of alpacas at pasture in southern Australia. Design A 2‐year survey of alpacas from two farms in South Australia and three in Victoria. Blood samples were collected from 20 to 30 alpacas on each farm on five occasions each year. Breed, gender, age and fleece colour of animals were recorded. Method Blood samples were assayed for plasma 2.5‐hydroxycholecalciferol (25‐OH D₃) and plasma inorganic phosphorus (Pi). Data sets from 802 animal samples were analysed by multiple regression to determine variables associated with low vitamin D status of alpacas. The relationship between plasma 25‐OH D₃ and plasma Pi was also investigated. Results Vitamin D status was significantly affected by month of sampling, with low values in late winter and high values in summer. Plasma vitamin D concentrations increased with age, were higher in alpacas with light fleeces than in those with dark fleeces and were also higher in the Suri than in the Huacaya breed. Plasma Pi concentrations were generally lower in alpacas with plasma 25‐OH D₃ values < 25 nmol/L. Conclusions Young alpacas with dark fleeces are most at risk from vitamin D insufficiency in late winter in southern Australia. The present study indicates that plasma Pi values are not a reliable indicator of vitamin D status of alpacas as assessed by plasma 25‐OH D₃ concentrations.     

Tolerance evaluation of overdosed dietary levels of 25‐hydroxyvitamin D3 in growing piglets

Forty‐eight, cross‐bred (GL × LW × P) piglets were used in a 42‐day tolerance trial to assess the effects of feeding diets supplemented with vitamin D or increasing levels of 25‐hydroxyvitamin D₃ (25‐OH‐D₃). Six‐week‐old piglets (24 castrate males, 24 females) were used. Two replicate groups of 6 piglets were randomized by weight and allocated to four dietary treatments. The control group (T1) was supplemented with 50 μg vitamin D₃/kg feed. The experimental groups received 25‐OH‐D₃ at the recommended dose (T2: 50 μg/kg = 1x), at 250 μg/kg (T3: 5x) or at 500 μg/kg (T4: 10x) respectively. Feed intake and daily weight gain were measured weekly, and the animals were examined by a veterinarian daily. After 42 days, body mass, blood, urine, bone and tissue samples were analysed and a pathology examination conducted. Dietary treatments had no significant effect on final body mass or daily weight gain. The 25‐OH‐D₃ plasma concentration in T1 was 17 ± 3 ng/ml (mean ± SD) while the respective values of the experimental groups were significantly increased in T2, T3 and T4. Tissue concentrations of 25‐OH‐D₃ were higher in liver and muscle for T3 and T4 and in skin for T4 than in T1. However, neither gross pathology nor histology, nor blood and urine characteristics, nor bone parameters were affected by dietary treatments. Weight of organs as well as dry matter, ash and calcium content of kidneys remained unaffected by dietary 25‐OH‐D₃ intake. Furthermore, no changes were observed for general indicators of health. The results of this study demonstrated that feeding piglets with 25‐OH‐D₃ at 5 or 10 times the recommended level had no adverse effects on any of the biological parameters measured. It was concluded that 25‐OH‐D₃ can be regarded as a supplement with a very high safety margin when used at the recommended level.