首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
AIM: To determine concurrent changes in serum methylmalonic acid (MMA) and vitamin B12 concentrations of ewes and their lambs on cobalt-deficient properties, subsequent to cobalt supplementation. METHODS: Three experiments were carried out on two farms. Groups of ewes (n=25-50) were either supplemented with cobalt bullets during late pregnancy, 23-47 days before the mean lambing date, or left unsupplemented. In two experiments, lambs from within each group were supplemented directly by vitamin B12 injection at 3-weekly intervals from birth, and in the third experiment by injection with micro-encapsulated vitamin B12 at tailing and 3 months later. Pasture samples were obtained for analysis of cobalt content at each sampling time. Blood samples were obtained and liveweight recorded from ewes and lambs at approximately monthly intervals. On one farm (two experiments), liver and milk samples were obtained from ewes and liver samples from lambs. RESULTS: Serum vitamin B12 concentrations in unsupplemented ewes fell below 250 pmol/L during early lactation in all experiments and mean concentrations as low as 100 pmol/L were recorded. MMA concentration was maintained below 2 micromol/L in serum from supplemented ewes but increased to mean concentrations ranging from 7 to 14 micromol/L at the nadir of serum vitamin B12 concentration during peak lactation. A significant liveweight response to supplementation was recorded in ewes on one property, and the vitamin B12 concentration in the ewes' milk and in the livers of their lambs more than doubled. No liveweight-gain response to supplementation was observed in lambs on this property. Mean serum MMA concentrations in lambs ranged from <2 in supplemented, to 19.2 micromol/L in unsupplemented lambs, and the latter had concurrent serum vitamin B12 concentrations of >300 pmol/L. Pasture cobalt concentration was lowest at 0.04-0.09 microg/kg dry matter (DM) on the property on which responses in lambs occurred but considerably higher (>0.09 microg/kg DM) on the property on which responses in ewes occurred. On the second property, serum vitamin B12 concentrations in lambs at tailing were extremely low (100 pmol/L), irrespective of supplementation of dams with cobalt. Mean serum MMA concentration was increased to 20 and 42 micromol/L in lambs from supplemented and non-supplemented ewes, respectively. Weight-gain response to direct supplementation of lambs with vitamin B12 occurred during suckling in the latter, but not the former. Lambs from ewes supplemented with vitamin B12 showed a much bigger increase in serum vitamin B12 concentrations a month after supplementation than did lambs from unsupplemented ewes (+1,400 pmol/L vs + 650 pmol/L). CONCLUSIONS: Serum MMA concentration gave a more precise indication of responsiveness to vitamin B12 or cobalt supplementation than serum vitamin B12 concentrations in ewes and lambs. Neither very low serum vitamin B12 nor elevated MMA concentrations were necessarily indicative of responsiveness to supplementation in suckling lambs, but the latter gave an early indication of impending responsiveness. Supplementation of the ewe with a cobalt bullet appeared to protect the growth performance of the lamb for 90 days and influence the subsequent serum vitamin B12 response in the lamb to vitamin B12 supplementation. CLINICAL SIGNIFICANCE: Supplementing ewes with cobalt bullets in late pregnancy can improve the vitamin B12 status of their lambs, and modify their response to vitamin B12 supplementation.  相似文献   

2.
AIM: To derive reference ranges for serum methylmalonic acid (MMA) for the diagnosis of cobalt/vitamin B12-responsiveness in lambs and critique existing serum vitamin B12 reference ranges. METHODS: Individual animal data from earlier supplementation trials, involving 225 ewes, 106 suckling lambs, 301 lambs during the suckling and post-weaning periods and 414 weaned lambs, for which weight gain to supplementation was observed, were used to derive relationships between serum vitamin B12 and MMA, and liveweight gain. RESULTS: Serum MMA concentrations were rarely elevated above the norm of <2 micromol/L when serum vitamin B12 concentrations were >375 pmol/L, and not elevated into the range where a liveweight response to supplementation occurred (>10 micromol/L) unless serum vitamin B12 concentrations were below 200 pmol/L. Suckling lambs were able to maintain high growth rates despite elevated serum MMA concentrations (>20 micromol/L). CONCLUSIONS: The current reference ranges used in New Zealand for serum vitamin B12 are set conservatively high. Serum MMA concentrations appear to allow better differentiation of a responsive condition than vitamin B12 concentrations. Serum MMA concentrations >13 micromol/L indicate responsiveness to supplementation whilst concentrations <7 micromol/L indicate unresponsiveness. In the range 7-13 micromol/L, variation in response was observed and predictability of response is less certain, but supplementation is advisable. CLINICAL RELEVANCE: The current reference ranges for vitamin B12 responsiveness are conservatively high and lead to over-diagnosis of vitamin B12 deficiency in ill-thriftiness of sheep.  相似文献   

3.
AIM: To compare serum analyses of vitamin B12 and methylmalonic acid (MMA) as indices of cobalt/vitamin B12 deficiency in lambs around weaning. METHODS: Lambs on five properties, considered to be cobalt- deficient, were supplemented with either cobalt bullets, or short- or long-acting vitamin B12 preparations. Blood samples, and in some cases liver biopsies, and liveweights were obtained at monthly intervals. Serum samples were assayed for vitamin B12 and MMA and liver for vitamin B12 concentrations. Pasture cobalt concentrations were measured on three of the properties. RESULTS: Pasture cobalt concentrations were generally maintained below 0.07 microg/g dry matter (DM) on the properties sampled. Growth responses to supplementation were observed on only 2/5 properties, despite serum vitamin B12 concentrations being within the currently used 'marginal' reference range (336-499 pmol/L) for at least 3 months on all properties and in the deficient reference range (0-335 pmol/L) for at least 2 months on all farms except one. Serum MMA concentrations in supplemented lambs were <2 micromol/L, except in those animals sampled 1 month after receiving treatment with a short-acting vitamin B12 injection. Serum MMA concentrations in unsupplemented animals on properties on which no growth response to supplementation occurred generally reached peak levels of between 4 and 7 micromol/L at the nadir of serum vitamin B12 concentration. When a growth response was observed, differences in weight gain between supplemented and unsupplemented lambs occurred as mean serum MMA concentrations increased from 9 to 14 micromol/L. On one property where supplementation commenced before weaning, normal growth rates were maintained despite serum vitamin B12 concentrations of 140 pmol/L and serum MMA concentrations in excess of 40 micromol/L serum. CONCLUSIONS: The possibility that current serum vitamin B12 references ranges for diagnosis of cobalt deficiency are set too high and lead to over-diagnosis of responsiveness to cobalt/ vitamin B12 supplementation is discussed. The suggestion is made that serum MMA concentrations in excess of 9-14 micromol/L will provide a more reliable diagnostic test for cobalt deficiency. However, there was sufficient variation between properties in the relationships between cobalt concentrations of pasture and serum vitamin B12 or MMA concentrations to require more rigorous testing of the reliability of using serum MMA concentration for this purpose. The possibility that differences in rumen fermentation and therefore propionate and vitamin B12 production could be involved is discussed. The measurement of serum MMA and vitamin B12 appears to be of little value whilst the lamb is still suckling. CLINICAL SIGNIFICANCE: Serum MMA concentration may offer advantages over serum vitamin B12 concentrations in the diagnosis of a cobalt/vitamin B12 responsiveness in weaned lambs.  相似文献   

4.
Medium wool ewes were injected with vitamin E and(or) Se over a 2-yr period to evaluate the influence of these treatments on reproduction. Ewes were divided randomly into four groups, consisting of a control, plus groups receiving monthly sc injections of either 272 iu vitamin E, 4 mg Se or 272 IU vitamin E plus 4 mg Se during pregnancy. Selenium administration increased (P less than .05) ewe blood Se concentrations, but had no effect (P greater than .10) on fertility (number of ewes lambing of ewes bred), prolificacy (number of lambs born/ewe lambing) or lamb sex ratio. Preweaning survival of lambs was increased (P less than .05) by ewe treatments with either Se or vitamin E and thus, treated ewes weaned approximately 20% more lambs/ewe mated than did control ewes.  相似文献   

5.
AIM: To compare serum analyses of vitamin B12 and methylmalonic acid (MMA) as indices of cobalt/vitamin B12 deficiency in lambs around weaning.

METHODS: Lambs on five properties, considered to be cobalt- deficient, were supplemented with either cobalt bullets, or short- or long-acting vitamin B12 preparations. Blood samples, and in some cases liver biopsies, and liveweights were obtained at monthly intervals. Serum samples were assayed for vitamin B12 and MMA and liver for vitamin B12 concentrations. Pasture cobalt concentrations were measured on three of the properties.

RESULTS: Pasture cobalt concentrations were generally maintained below 0.07 μg/g dry matter (DM) on the properties sampled. Growth responses to supplementation were observed on only 2/5 properties, despite serum vitamin B12 concentrations being within the currently used ’marginal‘ reference range (336–499 pmol/L) for at least 3 months on all properties and in the deficient reference range (0–335 pmol/L) for at least 2 months on all farms except one. Serum MMA concentrations in supplemented lambs were <2 μmol/L, except in those animals sampled 1 month after receiving treatment with a short-acting vitamin B12 injection. Serum MMA concentrations in unsupplemented animals on properties on which no growth response to supplementation occurred generally reached peak levels of between 4 and 7 μmol/L at the nadir of serum vitamin B12 concentration. When a growth response was observed, differences in weight gain between supplemented and unsupplemented lambs occurred as mean serum MMA concentrations increased from 9 to 14 μmol/L. On one property where supplementation commenced before weaning, normal growth rates were maintained despite serum vitamin B12 concentrations of 140 pmol/L and serum MMA concentrations in excess of 40 μmol/L serum.

CONCLUSIONS: The possibility that current serum vitamin B12 references ranges for diagnosis of cobalt deficiency are set too high and lead to over-diagnosis of responsiveness to cobalt/ vitamin B12 supplementation is discussed. The suggestion is made that serum MMA concentrations in excess of 9–14 μmol/L will provide a more reliable diagnostic test for cobalt deficiency. However, there was sufficient variation between properties in the relationships between cobalt concentrations of pasture and serum vitamin B12 or MMA concentrations to require more rigorous testing of the reliability of using serum MMA concentration for this purpose. The possibility that differences in rumen fermentation and therefore propionate and vitamin B12 production could be involved is discussed. The measurement of serum MMA and vitamin B12 appears to be of little value whilst the lamb is still suckling.

CLINICAL SIGNIFICANCE: Serum MMA concentration may offer advantages over serum vitamin B12 concentrations in the diagnosis of a cobalt/vitamin B12 responsiveness in weaned lambs.  相似文献   

6.
AIM: To obtain information on serum and liver vitamin B12 and urinary methylmalonic acid concentrations as diagnostic tests to predict a weight gain response to supplementation with vitamin B12 in young dairy cattle when grazing pasture of low cobalt content. Methodology. Forty dairy cattle (12 Friesian, 14 Friesian x Jersey and 14 Jersey) were allocated to two equal sized groups, treated and untreated, based on liveweight. At monthly intervals for 14 months, all animals were weighed, their serum and urine sampled, their liver biopsied and the pasture sampled from the paddocks they were grazing and going to graze. Serum and liver were assayed for vitamin B12 concentrations. For the first 5 months of the trial, urine was assayed for methylmalonic acid concentrations. Both washed and unwashed pasture samples were assayed for cobalt concentrations. RESULTS: No weight gain response occurred vitamin B12 supplementation in young growing cattle grazing pasture with a cobalt concentration of 0.04-0.06 mg/kg DM. For 5 months of the trial, liver vitamin B12 concentrations from untreated calves were in the range 75-220 nmol/kg and serum vitamin B12 concentrations were as low as 72 pmol/1. There was no associated growth response to supplementation. CONCLUSION: Further trials involving young cattle grazing pastures with cobalt concentrations less than 0.04 mg/kg DM are required to reliably determine liver and serum vitamin B12 concentrations at which growth responses to vitamin B12 or cobalt supplementation are likely under New Zealand pastoral grazing conditions.  相似文献   

7.
AIM: To investigate growth response of cobalt deficient lambs to increasing doses of microencapsulated vitamin B12, and to measure associated changes in serum and liver vitamin B12 concentrations over 243 days. METHODS: From a flock grazing pastures that had low cobalt (Co) levels (about 0.06 mg Co/kg dry matter), 4-6-week-old lambs (n=137) were assigned to four groups and received either no treatment or a subcutaneous injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B12 on Day 1. At approximately monthly intervals, all lambs were weighed and blood samples were collected from a selection (n=10) of monitor animals, up to Day 243. Liver biopsies were also carried out on the monitor lambs (n=8) on Days 1, 124 and 215. RESULTS: The vitamin B12-treated lambs grew significantly faster (p<0.001) than untreated animals. Liveweights after 243 days were 28, 45, 45 and 47 kg for the untreated, 3.0, 4.5 and 6.0 mg vitamin B12-treated lambs, respectively. Of the initial group of untreated lambs, 68% had to be removed before the end of the trial because of substantial weight loss, but none of the treated animals were similarly afflicted. Serum vitamin B12 concentrations increased in all vitamin B12-treated lambs, reaching a peak at Day 25, and those of the 4.5 and 6.0 mg vitamin B12-treated lambs remained significantly higher (except at Day 124) than the untreated lambs to Day 187. However, at Day 124, but not Day 215, the liver vitamin B12 concentrations of treated lambs were two to three times higher than those of controls. CONCLUSIONS: The growth rates of Co deficient lambs were markedly improved by injection of 3.0, 4.5 or 6.0 mg of microencapsulated vitamin B12, and liveweights were maintained for at least 243 days. Serum vitamin B12 concentrations were related to this growth response; concentrations of <220 pmol vitamin B12/l were associated with a 95% probability that lambs were Co deficient and would thus respond to Co/vitamin B12 supplementation. Based on these data, the current New Zealand reference criteria for Co deficiency should be reviewed. CLINICAL SIGNIFICANCE: An injection of 3 mg microencapsulated vitamin B12 given to lambs at tailing will treat Co deficiency and will increase and maintain liveweights in a flock for up to 8 months.  相似文献   

8.
AIM: To determine the effect of increasing doses of long-acting injectable vitamin B12 plus selenium (Se) given pre-mating on the vitamin B12 and Se status of ewes and their lambs from birth to weaning. METHODS: Four groups of 24 Poll Dorset ewes each were injected 4 weeks pre-mating with different doses of a long-acting vitamin B12 + Se product, containing 3 mg vitamin B12 and 12 mg Se per ml. The treatment groups received 5 ml (15 mg vitamin B12 + 60 mg Se), 4 ml (12 mg vitamin B12 + 48 mg Se), 3 ml (9 mg vitamin B12 + 36 mg Se), or no vitamin B12 or Se (control). Twelve of the twin-bearing ewes per group were selected for the study. Efficacy of the product was evaluated from changes in the concentrations of vitamin B12 in serum and liver, and of Se in blood, liver and milk in the ewes during gestation and lactation, and in their lambs from birth to weaning. Pasture samples in paddocks grazed by the ewes and lambs were collected at about 2-monthly intervals from 200-m transects. RESULTS: The flock was Se-deficient, as the mean initial concentration of Se in the blood of ewes was 182 (SE 20.3) nmol/L. Compared with untreated controls, all doses significantly (p < 0.01) increased concentrations of Se in the blood of ewes for at least 300 days. Selenium concentrations in milk were likewise increased throughout lactation, as were those in the blood and liver of lambs. The mean concentration of vitamin B12 in the serum of ewes was initially > 1,000 pmol/L, but this decreased within 28 days to < 460 pmol/L. Treatment with the 5-ml and 4-ml doses raised serum vitamin B12 concentrations of ewes for at least 176 days (p < 0.01), while their lambs had significantly greater concentrations of vitamin B12 in serum and liver for less than 37 days after birth. Tissue concentrations and duration of elevation of both vitamin B12 and Se were proportional to the dose administered. The mean concentrations of Se and cobalt (Co) in the pastures were 32 and 74 microg/kg dry matter (DM), respectively. CONCLUSIONS: Injecting ewes from a Se-deficient flock 4 weeks prior to mating with 48 or 60 mg Se and 12 or 15 mg vitamin B12 increased and maintained the Se status of ewes for at least 300 days, and of their lambs from birth to weaning. The vitamin B12 status of ewes was increased for at least 176 days and that of their lambs for less than 37 days. Due to the proportional nature of the response to increasing dosage, the dose rate of the formulation tested can be adjusted according to the severity of Se and Co deficiency in a flock. CLINICAL SIGNIFICANCE: A single subcutaneous injection of vitamin B12 + Se administered pre-mating to Se-deficient flocks is likely to prevent Se deficiency in ewes and their lambs until weaning, as well as increase the vitamin B12 status of ewes and their lambs until 5 weeks after lambing.  相似文献   

9.
In a controlled field study of three years' duration we evaluated the effect of cobalt supplementation on pathological changes in cobalt/vitamin B12-deficient Texel twin lambs grazing the same cobalt-deficient pasture. Semi-quantitative evaluation of the histopathology of liver and brain was done on 44 sets of twins. Pathological changes were related to blood concentrations of vitamin B12, methylmalonic acid, and homocysteine. Lesions were mainly confined to the liver and brain. Acute hepatic changes were characterized by steatosis, hepatocytic degeneration, and single cell necrosis. Chronic changes consisted of bile duct proliferation, the presence of ceroid containing macrophages, and fibrosis in the portal triads. Many non-supplemented lambs showed polymicrocavitation and Alzheimer type II reaction in the brain. Polioencephalomalacia was observed in three non-supplemented lambs but was regarded as a secondary lesion. Our results indicate that the main lesions found in cobalt/vitamin B12-deficient lambs are acute and chronic hepatitis. These lesions were associated with low concentrations of vitamin B12 and high concentrations of methylmalonic acid and homocysteine in the blood. The liver lesions were also associated with polymicrocavitation of the brain, probably as morphological evidence of hepatoencephalopathy.  相似文献   

10.
Serum vitamin B12 and methylmalonic acid (MMA) concentrations were used to monitor the development of cobalt (Co) deficiency and repletion from the deficient state in housed pregnant hill sheep. Serum MMA concentrations were less variable and provided a more accurate diagnosis of Co deficiency than serum vitamin B12. This was particularly the case for subclinical disease. However, unlike serum MMA, concentrations of the vitamin in serum could be used prognostically. The most precise diagnosis was provided by serum vitamin B12 and MMA data used in conjunction, but where one technique is to be used, serum MMA determinations are preferred.  相似文献   

11.
Abstract

Lambs grazing cobalt-deficient pastures and injected with hydroxocobalamine gained significantly more weight and excreted significantly less methylmalonic acid in the urine than untreated controls. Lambs with liver vitamin B12 levels in the range 0.1–0.2?g/g excreted less than 25 ?g of methylmalonic acid per ml of urine, whereas lambs with liver vitamin B12 concentrations of less than 0.1 ?g/g excreted greater amounts. Lambs in both groups had serum vitamin B12 concentrations less than 500 pg/ml.

No consistent diurnal variation in urinary methylmalonic acid concentrations was found for four lambs studied.

There was a decrease in the methylmalonic acid levels of urine after storage for more than 24 hours which could be prevented by acidification of the urine.

A mean urinary methylmalonic acid concentration greater than 30 ?g/ml for 10 animals randomly selected from a flock would indicate a cobalt deficiency in the flock as a whole.  相似文献   

12.
Thyroxine levels in serum of lambs and ewes were measured to determine their usefulness in assessing iodine nutrition of sheep. Lambs born on properties with no history of goitre had serum thyroxine concentrations more than twice that recorded in their mothers. These high values decreased to a level similar to that in the ewes after 8 weeks. In goitrous lambs younger than 2 weeks old, serum thyroxine concentrations were less than their ewe levels. Lambs born to ewes supplemented with iodine during pregnancy had higher thyroxine levels than lambs of control ewes.
A survey of 80 flocks of ewes in Victoria showed that 40% had a low mean thyroxine concentration (less than 50 nmol/l), but only one of these properties had reported an outbreak of goitre. It is suggested that serum thyroxine levels in newborn lambs may provide a more sensitive indicator of hypothyroidism associated with iodine deficiency than ewe levels.  相似文献   

13.
Fifty-two Targhee twin-bearing ewes were used in a factorial arrangement of treatments to investigate the role of supplemental vitamin E (vit E); 0 (NE) vs 400 IU of vit E x ewe x (-1)d(-1) (E) and parainfluenza type 3 (PI3) vaccination; none (NP) vs PI3 vaccination (P) in immune function. Parainfluenza type 3 vaccination was used to evoke an immune response. Ewes receiving PI3 were vaccinated at 49 and 21 d before the expected lambing date. Ewes receiving vit E were orally dosed daily, 32 to 0 d before lambing. Blood was collected from ewes at the time of the initial PI3 vaccination and 4 h postpartum. Blood was collected from lambs (n = 104) at 3 d postpartum. Ewe and lamb sera were analyzed for anti-PI3 antibody titers, immunoglobulin G (IgG) titers, and vit E concentrations. Colostrum was collected 4 h postpartum and analyzed for IgG. The model for ewe and lamb analysis included the main effects of vit E and PI3, sex (lambs model only), and their interactions. No interactions were detected (P > 0.20) for any ewe or lamb variables. Serum anti-PI3 titers were greater (P < 0.01) in P ewes and their lambs than NP ewes and their lambs. Serum vit E concentrations were greater (P < 0.01) in E ewes and their lambs than NE ewes and their lambs. Colostral IgG titers and serum anti-PI3 titers did not differ (P > 0.20) between E and NE ewes. Serum IgG titers in E ewes and their lambs did not differ (P > 0.15) from IgG titers in NE ewes and their lambs. Lamb anti-PI3 titers did not differ (P = 0.76) between lambs reared by E and NE ewes. These results indicate that, although supplemental vit E to the ewe increased lamb serum vit E concentration, it had no effect on measures used in this study to assess humoral immunity in the ewe or passive immunity to the lamb.  相似文献   

14.
Pregnant ewes were supplemented with dl-alpha-tocopheryl acetate, either as a single intramuscular dose (500 mg two weeks before lambing) or perorally (150 mg daily during 3-4 weeks before lambing). Ewes without such a supplementation were controls. The vitamin E supplemented ewes had nearly twice as high vitamin E (alpha-tocopherol) concentrations as the unsupplemented control ewes at lambing both in serum and in colostrum. The vitamin E concentration in colostrum was 5-11 higher than in milk 1 week after lambing. Both supplementations somewhat increased the vitamin E serum concentration of the newborn lambs, but the increase was negligible in comparison with the effect produced by the consumption of colostrum. All lambs had very low serum concentrations at birth. The lambs from the supplemented ewes had significantly higher serum values than the control lambs 24 h after birth. The ewes had somewhat higher selenium status at birth than their offsprings when evaluated by glutathione peroxidase (GSH-Px) in the erythrocytes. It seems reasonable that nutritional muscular degeneration may arise in newborn lambs with a normal selenium status if their vitamin E status is critical, either because of an inadequate consumption of colostrum or because of a vitamin E deficient diet during pregnancy with a low vitamin concentration of colostrum as a consequence.  相似文献   

15.
Bodyweight, plasma vitamin B12 and blood selenium concentrations were monitored in prime lambs given different forms of supplementation at 2 sites in separate years. At the first site treatment groups comprised control, vitamin B12 injection, selenium given orally and a combination of vitamin B12 and selenium. At the second site cobalt and selenium supplied in a glass bullet was compared with an untreated group. Significant sex-related responses were observed to treatment in terms of bodyweight and at site 2 in plasma vitamin B12 concentrations. A marked bodyweight response to glass bullet supplementation was observed in castrated male lambs but not in ewe lambs. These studies show that sex differences should be considered when investigating trace element deficiencies.  相似文献   

16.
AIM: To derive reference ranges for serum methylmalonic acid (MMA) for the diagnosis of cobalt/vitamin B12-responsiveness in lambs and critique existing serum vitamin B12 reference ranges.

METHODS: Individual animal data from earlier supplementation trials, involving 225 ewes, 106 suckling lambs, 301 lambs during the suckling and post-weaning periods and 414 weaned lambs, for which weight gain to supplementation was observed, were used to derive relationships between serum vitamin B12 and MMA, and liveweight gain.

RESULTS: Serum MMA concentrations were rarely elevated above the norm of <2 µmol/L when serum vitamin B12 concentrations were >375 pmol/L, and not elevated into the range where a liveweight response to supplementation occurred (>10 µmol/L) unless serum vitamin B12 concentrations were below 200 pmol/L. Suckling lambs were able to maintain high growth rates despite elevated serum MMA concentrations (>20 µmol/L).

CONCLUSIONS: The current reference ranges used in New Zealand for serum vitamin B12 are set conservatively high. Serum MMA concentrations appear to allow better differentiation of a responsive condition than vitamin B12 concentrations. Serum MMA concentrations <13 µmol/L indicate responsiveness to supplementation whilst concentrations <7 µmol/L indicate unresponsiveness. In the range 7–13 µmol/L, variation in response was observed and predictability of response is less certain, but supplementation is advisable.

CLINICAL RELEVANCE: The current reference ranges for vitamin B12 responsiveness are conservatively high and lead to over-diagnosis of vitamin B12 deficiency in ill-thriftiness of sheep.  相似文献   

17.
Thirty-eight pregnant Suffolk ewes were assigned randomly to a control group or implanted with approximately 2 g of testosterone propionate (TP) when they were between d 40 and 60 of gestation. Implants were removed 3 wk prior to lambing. Five ewe lambs born to implanted ewes and ten ewe lambs born to nonimplanted ewes were utilized in this experiment. Ram lambs were not used in this trial. No differences (P greater than .10) were observed for fecal, urinary and total N excretion and amount of N absorbed. Nitrogen retained (percentage of N intake and g/d) was higher (P less than .05) in prenatally androgenized ewe lambs than in control ewe lambs. Plasma insulin concentrations averaged 99% higher (P less than .05) in prenatally androgenized ewe lambs. Plasma insulin-like growth factor I (IGF-I) concentrations averaged 29% higher (P less than .06) in ewe lambs treated prenatally with testosterone. Nonesterified fatty acid (NEFA) concentrations averaged 41% higher (P less than .05) in prenatally androgenized ewe lambs. Significant (P less than .05) treatment x time effects were observed in plasma thyroxine, glucose and urea N concentrations of prenatally androgenized vs control ewe lambs. These significant modifications in the plasma metabolite and endocrine status could be an important element of the physiological mechanism(s) by which prenatal androgenization improves growth performance and leanness of ewe lambs.  相似文献   

18.
Twin-bearing Targhee ewes (Exp. 1, 1 yr, n = 42) and 1,182 single- and twin-bearing whiteface range ewes (Exp. 2, n = 8 experimental units over 2 yr) were used in a 2 x 2 factorial arrangement of treatments to determine the effect of supplemental energy source and level of vitamin E supplement on lamb serum metabolites and thermogenesis (Exp. 1) and on lamb growth (Exp. 2). During late gestation, ewes were individually fed (Exp. 1) or group-fed (Exp. 2) a daily supplement. Supplements were 226 g/ewe of daily safflower seed (DM basis; SS) with either 350 IU/ewe daily (VE) or no added supplemental (VC) vitamin E; or 340 g/ewe daily of a barley-based grain supplement (DM basis; GC) and either VE or VC. One hour postpartum in Exp. 1, twin-born lambs were placed in a 0 degrees C dry cold chamber for 30 min. Lamb rectal temperature was recorded every 60 s and blood samples were taken immediately before and after cold exposure. In Exp. 2, lambs were weighed at birth, at turnout from confinement to spring range (32 d of age +/- 7; turnout), and at weaning (120 d of age +/- 7). Ewes were weighed at turnout and weaning. In Exp. 1, a level of vitamin E x energy source interaction was detected (P < 0.10) for body temperature and change in NEFA and glucose concentrations. Lambs from SSVC ewes had the lowest (P = 0.01) body temperature and had decreased (P = 0.08) NEFA concentration. The SS lambs tended to have decreased (P < 0.11) concentrations of blood urea N (BUN) and thyroxine at 0 min than did lambs born to GC ewes. After 30 min of cold exposure, SS lambs had increased and GC lambs had decreased BUN, triiodothyronine, and triiodothyronine:thyroxine concentrations (P < 0.10). In Exp. 2, kilograms of lamb per ewe at turnout and weaning and lamb survival at weaning were greater (P < 0.07) for GC than SS lambs. Based on the decreased body temperature in SSVC lambs at birth, the greater change in BUN during the cold exposure for SS than GC lambs, and the decreased survival rate for SS than GC lambs, SSVC-supplemented ewes appeared to give birth to lambs with an apparently decreased energetic capacity. This may compromise the ability of the newborn lamb to adapt to extreme environmental conditions.  相似文献   

19.
At pasture outlet, mean plasma vitamin B12 varied between 210 and 1,200 pmol/l in 1 month old lambs, 19% of them had values below 250 pmol/l. In those put on OWLD pastures, mean values dropped after 2-4 weeks, and mostly stayed below 150 pmol/l throughout grazing. Plasma methylmalonic acid (MMA) rose above 5 mumol/l 2-8 weeks after outlet, and above 15 mumol/l 4 weeks later. Reduced growth occurred 3-8 weeks after plasma B12 dropped below 150 pmol/l, and 4-6 weeks after MMA rose above 5 mumol/l. Clinical OWLD was most often associated with plasma B12 less than 150 pmol/l and MMA greater than 15 mumol/l. Cobalt fertilization of pastures induced satisfactory plasma B12/MMA values for 3 succeeding years. Elevated plasma B12 was found 3 weeks after Co pellet dosing. The use of Co lick resulted in large individual variations in plasma B12/MMA. The control lambs, which were healthy and grew well on pastures which some years contained marginal/deficient cobalt, had plasma B12/MMA values which varied considerably. One year values indicated functional Co deficiency, but none developed OWLD, and growth was satisfactory, but less than other years. In these lambs, high MMA was not always associated with low B12, or depressed growth. OWLD occurred in Co/B12 deficient lambs, but Co/B12 deficient lambs on other pastures did not develop OWLD.  相似文献   

20.
In two trials an assessment was made of serum methylmalonic acid as a diagnostic criterion of cobalt status in housed cattle. Despite the small number of animals used the method showed some promise, and normal concentrations are tentatively suggested as being less than 2 mumole/litre, subclinically cobalt deficient 2 to 4 mumole/litre and cobalt-deficient greater than 4 mumole/litre. However, for assessing how cobalt status is likely to influence the rate of liveweight gain of cattle, measurements of both serum methylmalonic acid and vitamin B12 concentrations would appear to be better.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号