The vitamin B12 and Se status of lambs during their transition from milk-fed monogastric to grazing herbivore.

AIM: To estimate how the lamb's transition from a monogastric at birth to a grazing ruminant at weaning affects its dietary intake of trace nutrients from milk and pasture, and to determine whether its vitamin B12 and Se status changes during that period. METHODS: We reviewed published reports of field trials in New Zealand where flocks were managed on mixed sward pastures without additional supplements. Information on intakes of milk and pasture was drawn from studies of suckling lambs grazing with ewes for up to 20 weeks. We calculated the quantities of vitamin B12, Co and Se ingested and absorbed by lambs between birth and weaning. Trace nutrient status was based on concentrations of vitamin B12 in serum and Se in blood. Six studies met our inclusion criteria regarding age of lambs, supplementation and sampling frequency. In each, blood had been collected at regular intervals from birth to weaning. Changes over time in concentrations of vitamin B12 and Se were analysed using regression procedures. RESULTS: Estimated Se intake increased from approximately 5 µg/day near birth to 25 µg/day near weaning, but Se absorbed was less variable, being approximately 10 µg/day. Estimated vitamin B12 intake near birth was approximately 8 µg/day and increased to 90 µg/day by weaning, with the amount being absorbed increasing from 0.8 to 9 µg/day. Concentrations of trace elements in unsupplemented lambs among the six studies varied from deficient to adequate. Linear regressions indicated that there was little change in concentrations of vitamin B12 and Se between birth and weaning in four studies (p>0.05), and mean concentrations measured at docking did not differ from those at weaning in four studies where this could be assessed (p>0.1). CONCLUSIONS AND CLINICAL RELEVANCE: From newborn to weaned, a lamb's physiology develops from monogastric to ruminant. The change in diet from milk to pasture presents markedly different chemical forms and concentrations of some trace nutrients. Despite this, the vitamin B12 and Se status of the unsupplemented lambs in these studies changed little during their transition period. This finding supports early monitoring of lambs' trace element status. If a trace element deficiency is detected in lambs at or before docking, then administering supplements may be appropriate. If status is found to be adequate, then it will likely remain so until weaning, at which time the animals' trace element status should be re-evaluated.

Serum total iodine concentrations in pasture-fed pregnant ewes and newborn lambs challenged by iodine supplementation and goitrogenic kale.

Iodine deficiency can impair the reproductive performance of livestock and affect perinatal mortality of offspring, yet diagnosis of deficiency is complicated and guidelines for I supplementation are imprecise. We challenged pasture-grazing pregnant ewes with a long-acting I supplement and a goitrogenic forage, then monitored their I status during gestation and lactation and in their lambs from birth to weaning. Approximately 46 d into gestation, 376 ewes were assigned to 6 groups comprising 3 supplementation levels × 2 diet regimens. On d 0 the groups received an intramuscular injection of iodized oil providing 0, 300, or 400 mg of I. They grazed until d 23, then half of each supplementation group were fed brassica kale until d 85, then all groups returned to pasture for lambing (parturition approximately d 99) and remained there until weaning (d 192). Serum total I concentration (STIC) was measured repeatedly in 8 'monitor' ewes per group and in their lambs and in milk sampled postpartum. Severity of goiter was determined as the thyroid-weight:birth-weight (TW:BW) ratio in 82 newborn dead lambs. Mean ± SE STIC for all ewes was initially 42 ± 2 (range 24 to 105) µg/L. Diet did not affect I concentrations in ewe serum or milk. Responses to iodized oil were proportional to dose level; STIC increased to approximately 150 and 240 µg/L for the 300- and 400-mg I groups and remained greater than 0-mg I groups for 161 d (P < 0.05). Milk contained 26, 271, and 425 µg I/L for the 0-, 300-, and 400-mg I groups, respectively. Mean STIC of lambs from supplemented ewes did not differ by diet; concentrations for the 300- and 400-mg I groups were 237 and 287 µg I/L at birth, and by weaning all groups were similar (62 ± 3 µg/L). Lamb STIC measured at birth correlated with exposure to I in utero (R(2) = 0.59), which was estimated from the area under the curve (AUC) of ewe STIC measured during the last 99 d of gestation. Thyroid enlargement in lambs affecting the TW:BW ratio was a sensitive indicator of maternal nutrition, being greater with kale feeding (1.27 vs. 0.51 g/kg) and lesser with I supplementation (0.35 vs. 1.44 g/kg). Results support the use of STIC as a biochemical criterion. It was sensitive to the effects of I supplementation with responses in ewes and lambs proportional to dose level and it reflected the relationship between ewe and lamb I metabolism. However STIC did not discriminate between groups of ewes fed pasture vs. goitrogenic forage during pregnancy.

Vitamin B12 status and the effects of vitamin B12 supplementation during the first year of life of spring calves from pasture-fed dairy herds.

AIMS: To determine the vitamin B12 status of dairy calves during their first year of life, and to evaluate the benefits of vitamin B12 supplementation. METHODS: In Experiment I, 20 17-day-old heifer calves from the AgResearch Flock House herd were monitored until 198 days old. On Days 0 and 90 of the study, half of the animals received an injection of microencapsulated vitamin B12 at 0.12 mg/kg bodyweight. All received colostrum, milk replacer and calf meal, with ad libitum access to pasture. At regular intervals the calves were weighed and serum collected for vitamin B12 measurement. In Experiment II at Flock House and the adjacent Landcorp Tangimoana station, 80 150-day-old heifer calves were monitored until 342 days old. On Days 0 and 97, half of the animals received vitamin B12 as per Experiment I. At regular intervals samples were collected from 12 calves per group, to determine concentrations of vitamin B12 in serum. RESULTS: Mean concentration of vitamin B12 in milk replacer was 63 (SE 4) µg/kg dry matter (DM). Cobalt concentrations in calf meal were 0.45-1.58 and 0.07-0.28 mg/kg DM in pastures. From 17 to 198 days of age (Experiment I) mean concentrations of vitamin B12 in serum of the control group decreased from 119 (SE 8) to 57 (SE 5) pmol/L. From 150 to 342 days of age (Experiment II), overall mean concentrations of the control groups at Flock House and Tangimoana were 90 (SE 2) and 96 (SE 3) pmol/L, respectively. Vitamin B12 injections increased (p<0.001) serum concentrations for at least 90 days, with peak concentrations of 323 (SE 23) (Experiment I) and 520 (SE 22) (Experiment II) pmol/L reached 28-35 days after each injection. Liveweight gain was not increased by supplementation and there was no difference in final liveweight between groups. CONCLUSIONS: Concentrations of vitamin B12 in serum of unsupplemented calves prior to weaning indicated their vitamin B12 status was adequate due to the vitamin B12 and Co content of the milk replacer, and calf meal. Concentrations decreased during the transition to a pasture-based diet. Supplementation increased concentrations of vitamin B12 in serum but did not improve liveweight gains. CLINICAL RELEVANCE: Under this calf rearing system, vitamin B12 deficiency is unlikely to occur prior to weaning, and vitamin B12 supplementation is unlikely to increase growth rates of grazing calves when concentrations of vitamin B12 in serum are > 90 pmol/L.

A recent assessment of the elemental composition of New Zealand pastures in relation to meeting the dietary requirements of grazing livestock.

An understanding of the benefits and limitations of pasture feeding underpins sustainable grazing systems that produce milk and meat from ruminant livestock. We evaluated the mineral composition of 1,106 pasture samples collected independently from locations across New Zealand from 2001 to 2006. About half were submitted during 2002 and 2003, and 87% came from the North Island. Most herbage was from ryegrass and clover-dominated swards. The concentrations of Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, Se, or Zn were measured by nitric acid digestion followed by inductively coupled plasma optical emission spectroscopy or atomic absorption spectroscopy. Median concentrations for the macro elements were Ca 5.5, K 33, Mg 2.2, Na 2.0, P 4.0, and S 3.6 g/kg DM and for the trace elements were Co 0.10, Cu 8.4, Fe 131, Mn 74, Mo 0.66, Se 0.050, and Zn 43 mg/kg DM. Frequency histograms of concentrations revealed distributions ranging from near-normal to bottom-heavy skew with a long tail of high values. The minerals required for good plant growth were found at adequate concentrations in the majority of pastures. The exception was P; only 74% of pastures contained the recommended 3.5 mg P/kg DM. Results of the pasture survey were compared to the dietary intake requirements of cattle and sheep. For 7 elements, >95% of the pastures contained sufficiently high concentrations to meet the needs of unsupplemented animals. Exceptions were the Se dietary requirement, which was met by only 76% of pastures, the Co requirement of sheep met by only 54% of pastures, and the Cu, Na, and P requirements of cattle met by 25, 78, and 87% of pastures, respectively. Pasture analysis is an essential tool for identifying dietary insufficiency as well as unfavorable mineral balances where interactions could induce a deficiency, such as Cu × Mo and Mg × K. Monitoring of animals' nutritional status is also required to manage complex metabolic disorders related to peripartum flux of Ca and Mg. This study is the only large scale assessment of the mineral composition of New Zealand pastures to be published in 30 yr and the first to include a full range of trace elements. Knowing the proportion of pastures that are unlikely to meet nutritional requirements for some elements helps to define the risk areas for grazing livestock systems and provides an estimate of how prevalent mineral deficiencies might be if current practices of supplementation were not in place.

The impact of highly concentrated Mo and Cu dietary supplements, fed as a bolus, on the efficacy of chelated versus inorganic Cu in cattle on a low-Cu diet.

AIM: To compare the efficacy of chelated versus inorganic forms of dietary Cu supplements, fed as a bolus, when challenged by a daily bolus of dietary Mo in cattle on a low-Cu diet. METHODS: Forty non-lactating, Friesian dairy cows of adequate Cu status were assigned to four groups and fed a basal diet of baled silage containing 5.3 mg Cu and 0.4 mg Mo/kg DM. The experimental design was a factorial of two chemical forms of supplemental Cu and two levels of Mo intake, provided as pelleted grain supplements made from crushed barley/molasses plus Cu and Mo. The supplements contained 140 mg Cu/kg as Cu sulphate pentahydrate (CS), 140 mg Cu/kg as Cu glycinate (CG), CS plus 38 mg Mo/kg as sodium molybdate (CS+Mo), or CG plus 38 mg Mo/kg (CG+Mo). Commencing on Day 0, supplements were fed once daily (offered 1-1.2 kg/cow) and were completely consumed within 5-10 minutes, which constitutes a bolus type of administration. Liver samples were collected by biopsy at Days -24, 13, 41 or 47, and 69 for Cu determinations. RESULTS: The diets fed to the Cu+Mo groups were roughly equivalent to 25 mg Cu and 5.7 mg Mo/kg DM. Mean initial concentration of Cu in liver for all groups was 516 (SE 54) µmol Cu/kg fresh tissue. In cows supplemented with CS and CG, the final (Day 69) concentrations increased (p<0.01) to 939 (SE 166) and 853 (SE 163) µmol Cu/kg, respectively. These values were not different (p=0.72). For groups CS+Mo and CG+Mo, the final concentrations of 535 (SE 122) and 453 (SE 102) µmol Cu/kg were not different from initial values or from each other (p>0.25). The rate of accumulation of Cu in liver following bolus Cu and Mo intake was highly variable but was not affected by initial concentration of Cu in liver (p>0.9) or by the form of Cu (p>0.6). Mean rates of accumulation of Cu in liver were 4.0 (SD 3.8) and 0.65 (SD 2.0) µmol Cu/kg fresh tissue/day for the Cu-only treatments and the Cu+Mo treatments, respectively. CONCLUSIONS: When fed together as a bolus, high Mo intake negated the effect of supplemental Cu but it did not reduce liver Cu stores. There was no difference in the reaction of dietary Mo with chelated Cu (as glycinate) versus inorganic Cu (as sulphate) dietary supplements.

Lack of production response in grazing dairy cows supplemented with long-acting injectable vitamin B12.

AIM: To determine the concentrations of vitamin B12 in serum, liver and milk that identify adequate vitamin B(12) status in grazing lactating cows, based on no change in milk production in response to supplementation with vitamin B12. METHODS: In October 2005, in early lactation, Friesian cows from one herd were injected S/C with 60 or 90 mg long-acting vitamin B12, or no injection (Control; n=39 per group, Day 0). Pasture samples were collected for Co determination at monthly intervals over 82 days. Concentrations of vitamin B12 in milk and serum (n=10 per group) and in liver (n=5 per group) were assessed over 124 days. Milk production and composition were determined on four occasions for all cows. RESULTS: Mean concentrations of Co in pasture ranged from 0.11 to 0.34 mg/kg dry matter (DM). Mean initial concentrations of vitamin B12 in milk, serum and liver were 1,520, 128 pmol/L and 1,092 nmol/kg fresh tissue, respectively. Administration of 60 and 90 mg vitamin B12 had similar effects and increased concentrations of vitamin B(12) in milk by 3-fold over controls on Day 50 (7,410 vs. 2,350 pmol/L; p<0.001) and 1.6-fold on Day 124 (3,470 vs. 2,210 pmol/L; p=0.011). Treatment with 60 and 90 mg vitamin B12 increased concentrations of vitamin B12 in serum, by at least 5-fold over controls on Day 50 (880 and 1,040 vs. 160 pmol/L; p<0.001). The two treatments increased concentrations of vitamin B12 in liver by only 1.5 fold over controls on Day 50 (1,660 and 1,900 vs. 1,200 nmol/kg fresh tissue; p<0.005). Treatment had no effect at any sampling time on daily milk volume or milk solids, fat or protein percentages. CONCLUSIONS: Concentrations of vitamin B12 in serum >128 pmol/L indicated adequate vitamin B12 status in grazing lactating cows. Supplementation with 60 or 90 mg vitamin B12 increased and maintained concentrations of vitamin B12 in serum for up to 124 days, but there was no effect on milk production. Milk was enriched in its vitamin B12 content, which would provide enhanced nutrition for calves or humans. Compared with 60 mg, the larger dose provided little additional benefit. CLINICAL RELEVANCE: Long-acting injectable vitamin B12 used to treat and prevent vitamin B12 deficiency is unlikely to improve the milk production of grazing cows when concentrations of vitamin B12 in serum are >128 pmol/L.

The role of liver Cu kinetics in the depletion of reserves of Cu in dairy cows fed a Cu-deficient diet.

AIM: To determine how the concentration of Cu in liver affects the rate of depletion of that Cu when cows are fed a Cu-deficient diet under experimental conditions, and to mathematically model the rate of depletion of Cu over time. METHODS: In June 2010, 25 non-lactating Friesian cows were assigned to three groups such that initial mean concentrations of Cu in liver were 265, 534 and 1,486 µmol Cu/kg fresh tissue (Day 0). All cows were managed as a single group and fed a Cu-deficient diet of primarily baled silage. No mineral Cu supplements were given. Liver biopsies were collected from cows on Days 0, 53, 98 and 161 to determine concentrations of Cu. At about the same time, samples of silage and pasture herbage were collected to determine Cu, Mo and S concentrations. RESULTS: Median concentration of Cu in silage was 6.5 (min 6, max 9) mg/kg DM. Concentration of Cu in liver decreased in all groups (p<0.001), over the duration of the study. The amount of Cu depleted from liver was greater in groups that started the study with higher initial concentrations of Cu in liver. The rate of decline followed exponential first-order kinetics with an elimination rate constant k of 0.0057 (CI 95%=0.0039-0.0074), meaning that about 0.57% of liver Cu reserves were depleted each day. For individual cows this loss amounted to 0.1-14 µmol Cu/kg liver/day. CONCLUSIONS AND CLINICAL RELEVANCE: Depletion of Cu from liver was dependent on initial concentration of Cu. These results can be used to predict how long an unsupplemented herd will remain in adequate Cu status, which adds confidence to decisions about when Cu supplementation should be withdrawn or reinstated. Cows with high concentrations of Cu in liver can maintain adequate Cu status for months without supplements. Intake of less Cu and more Mo would increase the rate of depletion, and seasonal factors would also have some influence.

Loss of reserves of Cu in liver when Cu supplements are withdrawn from dairy herds in the Waikato region.

AIM: To monitor the consequences of withdrawing mineral Cu supplements from two dairy herds with initially high concentrations of Cu in liver. METHODS: Two herds were selected from dairy farms in the Waikato region of New Zealand that participated in an earlier survey of Cu supplementation practices and Cu status of dairy cows. The herds were fed pasture, grass and maize silage, plus palm kernel expeller (PKE) containing 25-30 mg Cu/kg dry matter (DM) fed at 2-4 kg/cow/day. No mineral Cu supplements were supplied from January 2009. Pasture samples were collected for mineral analysis in September 2008 and April 2009. Concentration of Cu in liver biopsies from the same 9-10 cows per herd was measured on three occasions between April 2009 and May 2010. RESULTS: Pastures on both farms contained 10 mg Cu/kg DM, 0.1-0.5 mg Mo/kg DM and 3.5-4.0 g S/kg DM. The initial herd mean concentrations of Cu in liver were 1,500 (SD 590) and 1,250 (SD 640) µmol Cu/kg fresh tissue. In the absence of mineral Cu supplements, those mean concentrations decreased over 12 months to 705 (SD 370) and 1,120 (SD 560) µmol Cu/kg fresh tissue, respectively. For cows in the first herd, the rate of depletion of liver Cu reserves was influenced by initial concentration of Cu, such that high concentration led to faster loss according to first-order kinetics. CONCLUSIONS: Mineral Cu supplementation was not necessary over 12 months for two dairy herds with mean concentrations of Cu in liver >1,250 µmol Cu/kg fresh tissue, grazing pastures containing 10 mg Cu/kg DM and concentrations of Mo <1 mg/kg DM. The quantity and particularly the duration of feeding PKE appeared to be a factor in whether or not the herd lost substantial reserves of Cu in liver during the year. However, the Cu status of both herds in this study was more than adequate to support late pregnancy and mating. CLINICAL REVELANCE: Copper status of the herd should be monitored and on-farm management of Cu nutrition should take into account all sources contributing to daily intake of Cu. Where Cu supplementation has been excessive and there is risk of chronic Cu toxicity, mineral Cu supplements may be withdrawn for a period commensurate with the expected rate of liver Cu depletion.

Kanagawa-negative, tdh- and trh-positive Vibrio parahaemolyticus isolated from fresh oysters marketed in Fortaleza, Brazil.

Between October 2008 and June 2009, 15 samples of 10 live oysters each (Crassostrea rhizophorae) measuring 8.31-10.71 cm were purchased from a restaurant on the seashore of Fortaleza, Brazil. The Vibrio count ranged from 75 (estimated) to 43,500 CFU/g. Fourteen species were identified among the 56 isolated Vibrio strains, with V. parahaemolyticus as the most prevalent. Two of the 17 V. parahaemolyticus strains were urease-positive and tdh- and trh-positive on multiplex PCR, but neither produced ß-hemolysis halos in Wagatsuma agar. Thus, fresh oysters served in natura in Fortaleza, Brazil, were found to contain Vibrio strains known to cause gastroenteritis in humans.

High and variable copper status identified among dairy herds in the Waikato region by concentrations of Cu in liver sourced from biopsies and cull cows.

AIMS: To document the Cu supplementation practices on dairy farms in the Waikato region, determine the Cu status of those herds, and compare the suitability of liver samples sourced from biopsies and cull cows for assessing Cu status. METHODS: During spring 2008, concentrations of Cu, Mo and S were determined from pasture samples from 24 dairy farms. Feeding regimens, herd size, milksolids production, soil type, fertiliser policy and Cu supplementation practices were recorded for each property. Based on these data, 10 monitor farms were selected to represent a range of Cu intakes for herds, from 5 to 12 mg Cu/kg dry matter (DM). On each monitor farm 12 healthy lactating cows were selected for liver biopsy and collection of blood samples during the following autumn. Around the same time, livers were collected from 12 cull cows per farm when they were slaughtered, and samples of pasture were again collected from each farm. Concentrations of Cu were measured in all tissue samples. RESULTS: Concentrations of Cu in pasture tended to be higher (mean 10.4 vs 8.2 mg/kg DM) in the autumn than spring, while concentrations of Mo were lower in the autumn (mean 0.35 vs 1.07 mg/kg DM). Most of the 24 farms used Cu supplementation in some form. Mean concentrations of Cu in liver for herds ranged from 640 (SD 544) to 2,560 (SD 474) micromol/kg fresh tissue in biopsies, and 520 (SD 235) to 2,610 (SD 945) micromol/kg in liver from cull cows. Mean concentrations of Cu in serum ranged from 7.9 to 13.4 micromol/L. The variability in concentrations of Cu for each farm was greater for liver (CV 50%) than serum (CV 21%). For individual cows, concentrations of Cu in liver, obtained by biopsy, and serum were not correlated. CONCLUSIONS: The concentration of Cu in liver of dairy cows reflected widely differing dietary intakes of Cu between herds, although levels indicated an adequate Cu status on all farms in this study. Use of either biopsy samples or livers from cull cows were indicative of the Cu status of the herd. Wide variation in observed concentrations of Cu in liver indicated that at least 12 cows per herd should be sampled. On farms with intensive, long-term Cu supplementation programmes there is a risk of chronic Cu toxicity in some animals. Thus, the Cu status of dairy herds should be determined, and monitored, before making any recommendations regarding supplementation.

Accumulation and depletion of liver copper stores in dairy cows challenged with a Cu-deficient diet and oral and injectable forms of Cu supplementation.

AIM: To quantify the capacity of the liver to respond to a Cu-deficient diet and various forms of Cu supplementation in dairy cows with high Cu status. METHODS: Sixty non-pregnant, non lactating mixed-age Friesian dairy cows were fed baled silage for 116 days, containing 5.8 mg Cu/kg dry matter (DM), that provided an inadequate Cu intake. They were either unsupplemented (Control); or treated thrice weekly orally with solutions containing the equivalent of 150 mg Cu/day as copper sulphate pentahydrate (CS), copper amino chelate (CAC), or copper glycinate (CG); 16 g Cu as CuO wire particles, administered in an intra-ruminal bolus on Day 0; or 100 mg Cu as calcium copper edetate, administered by S/C injection on Days 0 and 58. On Days -5, 14, 28, 58, 86 and 116, liver biopsies and blood samples were obtained for determination of Cu. RESULTS: Mean initial concentrations of Cu in liver for all groups was 827 (SE 42) micromol/kg fresh tissue. In control cows, this decreased to 552 micromol/kg on Day 116, and averaged 670 micromol/kg over the length of the trial. Oral forms of Cu supplementation increased overall mean concentrations in liver to 960 (SE 79), 1,050 (SE 81) and 1,100 (SE 84) micromol/kg for CS, CAC and CG, respectively, but there was no difference between form of supplement. Mean concentrations were significantly increased by bolus treatment, but not by injection. Concentrations of Cu in serum in all groups decreased from 12.1 (SE 0.3) to 10.4 (SE 0.6) micromol/L by Day 116, with no differences due to treatments. The initial concentration of Cu in liver significantly affected the rate of accumulation of Cu among cows supplemented orally. In cows with an initial concentration <1,100 micromol/kg, the average increase was 4.1 micromol/kg fresh tissue/day, whereas rates were variable, even negative, when initial concentrations were >1,100 micromol/kg. Release of Cu over 116 days in cows given the bolus was calculated to be equivalent to an oral intake of CS of 106 mg Cu/day. CONCLUSIONS: In dairy cows with a high Cu status fed a Cu-deficient diet, responses to supplementation with two chelated forms of Cu administrated orally were similar to those due to CS. Copper as CuO was about 77% as effective as oral supplementation with chemically similar inorganic Cu. Initial concentrations of Cu in liver influenced the rate of accumulation following oral supplementation. CLINICAL RELEVANCE: Changes in concentrations of Cu in liver were readily observed following oral supplementation over a wide range of initial concentrations, whereas these changes could not be detected in serum. The liver is thus a good index of the Cu status of dairy cows.

The impact of high zinc intake on the copper status of dairy cows in New Zealand.

AIM: To determine the effect of a high Zn intake on the concentration of Cu in the liver of dairy cows. METHODS: Sixty non-pregnant, non-lactating, mixed-age Friesian dairy cows were randomised into four groups: unsupplemented control; thrice weekly oral treatment with 350 mg Cu (equivalent to 150 mg Cu/day) as CuSO(4) x 5H(2)O; a ZnO bolus releasing 6.628 g Zn/day given on Days 0 and 28; and oral treatment with Cu and ZnO boluses. The cows were fed baled silage for the duration of the study (56 days). On Days -12, 14, 28, 42 and 56 liver biopsies were collected for determination of concentrations of Cu, and blood samples for measurement of Cu and Zn in serum. RESULTS: Mean concentrations of Cu in the liver of unsupplemented control cows decreased from an initial 717 (SE 108.5) to 396 (SE 88.0) micromol/kg fresh tissue on Day 28, and then increased to 542 (SE 105.3) micromol/kg fresh tissue on Day 42, before decreasing to 434 (SE 81.6) micromol/kg fresh tissue on Day 56. Administration of ZnO resulted in no change in the concentration of Cu in liver compared with controls. Supplementing with 150 mg Cu/day significantly increased the concentration of Cu in liver, compared with controls, to 1,074 (SE 105.2) micromol/ kg fresh tissue on Day 56. Treatment with ZnO significantly reduced concentrations of Cu in liver on Day 56, compared with Cu-supplemented cows, to 786 (SE 107.7) micromol/kg fresh tissue. The treatments had no effect on concentrations of Cu in serum. In cows given the ZnO, mean concentrations of Zn in serum increased from 17 (SE 0.6) on Day 0 to 30 (SE 1.7) micromol/L on Day 14, then decreased to 20 (SE 1.3) micromol/L on Day 28, increased to 40 (SE 2.9) micromol/L on Day 42, then decreased to 24 (1.16) micromol/L on Day 56. In cows given ZnO plus Cu, concentrations of Zn in serum were significantly greater than in cows only given ZnO on Day 41 (46 (SE 2.71) vs 35 (SE 3.23) micromol/L, respectively). Mean concentrations of Cu, Mo and Zn in the baled silage were 4.4, 0.5 and 21 mg/kg dry matter (DM), respectively. CONCLUSIONS: High Zn intakes used in the prevention of facial eczema in dairy cows had little effect on concentrations of Cu in liver when the Cu intake was low, but decreased the efficacy of a Cu supplement by about 50%. CLINICAL RELEVANCE: When using Zn as a prophylactic treatment for facial eczema the level of Cu supplementation should be adjusted, which may mean that in some situations it is recommended not to supplement cows with Cu.

Abnormal hematological indices in cirrhosis.

Abnormalities in hematological indices are frequently encountered in cirrhosis. Multiple causes contribute to the occurrence of hematological abnormalities. Recent studies suggest that the presence of hematological cytopenias is associated with a poor prognosis in cirrhosis. The present article reviews the pathogenesis, incidence, prevalence, clinical significance and treatment of abnormal hematological indices in cirrhosis.

The effect of age on the fluoride concentration in the metacarpus of grazing sheep in New Zealand.

AIM: To determine the concentration of fluoride (F) in the metacarpi from ewes of varying age, which had been grazing pastures that had been regularly topdressed with phosphatic fertilisers, which contain F as a contaminant, for at least 30 years. METHODS: Three groups of 10 ewes aged 6-8, 18-20 and 60-72 months were selected from seven research farms with a known fertiliser history, representing the major sheep farming regions of New Zealand. Lambs were born and remained on the property. The sheep were collected and slaughtered in autumn, and the right metacarpus removed for determination of F content. Representative samples of topsoil (0-30- and 30-60-mm depths) were also collected for determination of F content. RESULTS: The total concentration of F in topsoil on the farms ranged from 161 to 712 mg/kg. The overall mean concentrations of F in metacarpi from 6-8-, 18-20- and 60-72-monthold ewes were 170 (SE 9.9), 308 (SE 13.9) and 480 (SE 28.4) mg/kg dry matter (DM), respectively. On six farms, lambs which had been exposed to limited or no ingestion of soil had the lowest concentration of F in their metacarpi. Generally, there was a curvilinear relationship between age and concentration of F in the metacarpi of sheep. On the seventh farm, the concentrations of F in the metacarpi from the 6-8- and 18-20-month-old sheep were similar but lower than those of the 60-72-month-old ewes. The area of soils on the farm where the 6-8-month-old-sheep were grazing had higher total concentrations of F in topsoil (271 mg/kg) than those soils grazed by the 18-20-month-old sheep (205 mg/kg), and this may be one reason for the elevated concentration of F in the metacarpi of the younger ewes. The concentrations of F in metacarpi, at any age, were not related to the concentration of F in topsoils. CONCLUSIONS: Many factors can influence the amounts of F in soil ingested by grazing sheep and the concentration of F in their bone. The concentration of F in the metacarpi of ewes generally increased curvilinearly with age, and the rate of accumulation of F in bone was greatest in young sheep. The potential risk of chronic fluorosis occurring in sheep grazing pastures in New Zealand is low for animals managed in a manner similar to the flocks studied, given the highest mean concentration of F was 601 mg/kg DM, observed in metacarpi from 60-72-month-old ewes, and that a concentration of at least 2,400 mg/kg DM is the threshold for chronic fluorosis.

A practical approach to managing the risks of iodine deficiency in flocks using thyroid - weight: birthweight ratios of lambs.

AIM: To establish a protocol for determining the iodine status of a flock and managing the risks of iodine deficiency, using thyroid-weight:birthweight ratios of newborn lambs and serum iodine concentrations of ewes. METHODS: Data were collected from iodine supplementation studies in Southland and Rangitikei, of sheep fed exclusively pasture or pasture plus brassica during the latter half of gestation (n=350, or 89 per treatment group). The ewes were supplemented pre-mating or at the time of pregnancy scanning with an injection of long-acting iodised oil. Serum iodine concentrations were measured in ewes prepartum in Rangitikei and postpartum at both locations. The thyroid-weight:birthweight ratios (as g/ kg) in 229 newborn lambs were determined at post-mortem examination and compared between iodine supplemented vs unsupplemented flocks using probit analysis. Samples of pasture and kale were analysed monthly for determination of iodine and selenium. RESULTS: Initial mean serum iodine concentration of all ewes was 41 mug iodine/L. Supplementation increased serum iodine concentrations regardless of forage fed, and concentrations remained high for between 127 and 206 days. The range of thyroid-weight:birthweight ratios in lambs from supplemented ewes was 0.09-0.70 (mean 0.35, standard deviation (SD) 0.147) g/kg. Among lambs from unsupplemented ewes, the range was much wider (0.21-8.5; mean 1.61, SD 1.95 g/kg). About half of those ratios were >0.8 g/kg and clearly indicative of goitre, including 62% from the groups on brassica and 18% from the Rangitikei group fed exclusively pasture. Probit calculations showed that a ratio of 0.40 (95% confidence interval (CI)=0.29-0.47) g/kg predicted with 35% probability, and a ratio of 0.80 (95% CI=0.70-0.99) g/kg predicted with 90% probability that a lamb came from an unsupplemented flock. CONCLUSIONS: Compared to iodine concentrations in forages, thyroid-weight:birthweight ratios more accurately reflected the iodine status of the flock and could be used to identify which flocks to supplement the following year. Serum iodine concentrations of ewes measured before or after lambing did not reflect forage fed, but values near 40 mug/L were associated with goitrous lambs. CLINICAL RELEVANCE: Thyroid-weight:birthweight ratios >0.8 g/kg were indicative of iodine deficiency, and ewes should be supplemented pre-mating or during pregnancy to prevent goitre the following year. Ratios <0.4 g/kg rarely occurred among deficient flocks, so the probability of benefit from supplementation was low. Intermediate ratios were ambiguous, and the iodine status of the flock could not be determined from biomarkers. In such cases individual-farm supplementation trials might be required to detect and manage the risks of marginal deficiency.

The effect of a temporal change in ingestion rates of fluorine (F) in soil on the concentration of F in serum and bone of young sheep.

AIM: To determine the changes in concentrations of fluorine (F) in serum and bone of young sheep given a high intake of F, as F in soil, followed by a low intake of F, to simulate the varying intakes experienced by grazing sheep. METHODS: Sixty autumn-born, weaned, mixed-sex lambs were randomly divided into two groups (n=30). One group (Control) was fed a low-F (12 mg/kg dry matter; DM) lucerne/ grain diet for 345 days, while the other group (High soil-F) was fed a high-F (224 mg/kg DM) lucerne/grain diet containing 10% soil for 94 days and then a low-F diet for a further 251 days. Blood samples were collected on Days 1, 32, 94, 108, 153, 214, 280 and 345, to determine concentrations of F in serum. Groups of five or six animals from each group were killed on Days 1, 94, 153, 214, 280 and 345, to collect radii and humeri for determination of F content. The sheep were weighed at about 6-8-weekly intervals. RESULTS: Initial liveweight of the sheep was 22.1 (standard error (SE) 1.12) kg and the mean liveweight gains were 270 (SE 22.1) and 170 (SE 12.4) g/day from Days 1 to 94 and 95 to 330, respectively. The mean initial (Day 1) concentration of F in serum was 0.03 (SE 0.005) mg/L, and this changed very little for animals on the low-F diet. In sheep on the high soil-F diet, the concentration of F in serum reached 0.38 (SE 0.021) mg/L at Day 94 but after being placed on the low-F diet concentrations decreased to 0.04 (SE 0.006) mg/L after 14 days (Day 108) and then remained at about this low level for the remainder of the duration of the study. The mean concentrations of F in the humerus and radius of the lambs at Day 1 were 161 (SE 19.4) and 159 (SE 20.4) mg/kg DM, respectively, which increased to 2,784 (SE 80.6) and 1,805 (SE 51.5) mg/kg DM, respectively, at Day 94 in lambs fed the high soil-F diet, then decreased to 1,075 (SE 58.1) and 1,064 (SE 61.6) mg/kg DM at Day 153, and then progressively increased to 1,669 (SE 57.7) and 1,312 (SE 30.8) mg/kg DM at Day 345. CONCLUSIONS: The ingestion of F in soil by sheep markedly increased their concentrations of F in serum and bone, but when the soil was removed and they were fed a low-F diet, concentrations of F in serum decreased to baseline levels within 14 days while concentrations in the bone only decreased to 60-70% of the peak concentration, indicating that some of the F in bone was remobilised.

Dose response effects of long-acting injectable vitamin B12 plus selenium (Se) on the vitamin B12 and Se status of ewes and their lambs.

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.

Effect of ingestion of soil on the iodine, copper, cobalt (vitamin B12) and selenium status of grazing sheep.

AIM: To determine the impact of ingestion of soil on the iodine (I), selenium (Se), copper (Cu) and cobalt (Co; vitamin B12) status of young sheep. METHODS: Twenty young sheep were divided into two groups; one group was fed lucerne pellets, while the other group was fed lucerne pellets plus 100 g soil, for 63 days. At the end of the study the animals were blood-sampled, slaughtered, and the liver removed, and concentrations of I, Cu, vitamin B12 and Se were determined. RESULTS: The ingestion of soil significantly increased concentrations of I and vitamin B12 in serum, but had no effect on concentrations of Cu and Se in serum/blood and liver, and vitamin B12 in liver. CONCLUSION: Ingested soil can be a significant source of I and Co (vitamin B12) for grazing sheep.

Enlargements of the distal third metacarpus and metatarsus in Thoroughbred foals at pasture from birth to 160 days of age.

AIMS: To assess the relationship between the radiographic and microscopic appearance of the physeal regions of the distal third metacarpal (Mc3) and metatarsal (Mt3) bones of Thoroughbred foals at 160 days of age, and to clinically assess changes in contour of the distal Mc3 and Mt3 physeal regions from birth to 160 days of age. To assess relationships between maximum clinical physis scores and age, time of year, foal's sex, condition score, growth rate, copper (Cu) concentration in the liver of the foal, and supplementation of the dam with Cu in late gestation. METHODS: Dams were given Cu (n=5 and n=11, in Years 1 and 2, respectively) or saline (n=5 and n=12, in Years 1 and 2, respectively) injections in late gestation. Liver biopsies were harvested from foals in the first week of life, and the whole liver homogenised after the animals were euthanised at around 160 days of age, to determine Cu concentrations. Pasture samples were collected every 4-8 weeks for analysis of mineral composition. During Year 1, 10 foals were weighed and examined every 2 weeks from birth to 160 days of age for evidence of pain and lameness in the distal Mc3/Mt3. In Year 2, 23 foals were weighed, condition-scored and examined for evidence of pain and lameness weekly for the first 5 weeks of life, then every 2 weeks from birth to 160 days of age, and a clinical physis score for the distal Mc3/Mt3 given. Cabinet radiographs of frontal slices of the physeal region of the distal Mc3/Mt3 at around 160 days of age were given a radiographic physis score. Physes were then examined histologically for evidence of abnormal endochondral ossification. RESULTS: Gross enlargements of the distal Mc3 and Mt3 were observed in all foals in this study, but were not associated with lameness, pain or inflammation. The most severe clinical physis scores occurred over 2 months in late summer/autumn, and were not influenced by the foal's growth rate, sex, or Cu concentration in the liver, or treatment of dams with Cu in late gestation. The clinical physis score was highly correlated to radiographic evidence of shouldering in the forelimb and hindlimb (both p<0.001). Focal disturbances in endochondral ossification were evident radiographically and histologically in the some of the physes at 160 days of age. The mineral composition of pasture was similar in Years 1 and 2, and concentrations of Cu and zinc were below those currently recommended for growing horses. CONCLUSIONS: Gross enlargements of the distal Mc3 and Mt3 were not consistent with previous descriptions of physitis. Results suggest that while many Thoroughbred foals at pasture will have visible boney enlargements of the distal Mc3/Mt3 in the first 5 months of life, few have physeal cartilage abnormalities or significant compromise of endochondral ossification. The importance of these clinical swellings may be overestimated, and they may more appropriately be called physiological enlargements associated with remodelling of bone.

Articular / epiphyseal osteochondrosis in Thoroughbred foals at 5 months of age: influences of growth of the foal and prenatal copper supplementation of the dam.

AIMS: To determine the influence of copper (Cu) supplementation by injection of mares in late gestation on the frequency and severity of osteochondrosis (OC) lesions in their foals at around 160 days of age. To determine if there was any influence of the concentration of Cu in the liver, growth rate, birthweight, weight at 160 days of age, fatness, sex, or year of birth of the foal on the frequency and severity of OC lesions. To determine the influence of dam's age, and sex and birthweight of the foal on the growth rate from birth to 160 days of age, and weight at 160 days of age. METHODS: Thirty-three Thoroughbred foals, born in two consecutive years, were weighed every 2 weeks from birth. The dams had been supplemented with parenteral Cu or saline during late gestation, and the supplementation regimens were different in each year. Foals had liver biopsies harvested at birth for determination of Cu concentration. Pasture samples were collected every 4-8 weeks for analysis of concentration of Cu and zinc (Zn). At 160 days of age, articular cartilage of long bones was examined. Gross lesions were counted and scored, then sawn and radiographed, and processed for histopathology. Lesions were given radiographic scores and histopathological scores. Maximum scores for each lesion were combined to give a total OC score for each joint and each foal. The fatness of 20 foals (10 each from Years 1 and 2) at 160 days of age was determined chemically. RESULTS: Supplementation of dams with Cu had no significant effect on the concentration of Cu in the liver of foals at birth, or on the frequency or severity of lesions in articular cartilage at 160 days of age. The Cu and Zn concentrations of pasture were similar in Years 1 and 2, and were lower than current recommendations. All foals in Year 2, and 9/10 foals in Year 1 had irregularities in cartilage that was confirmed histologically to be indicative of OC. The average number of lesions per foal was 4.7 (SD 1.1) and 5.7 (SD 1.1) in Years 1 and 2, respectively. However, the severity of the lesions was considered mild, and no foals showed any clinical evidence of OC while alive. The number of lesions in the tarsocrural (TC) joint and the TC OC score at 160 days were positively associated with average daily weight gain (ADG) in the previous 4 weeks (p=0.005 and p=0.001, respectively). There was no significant effect of sex, fatness, birthweight, weight at 160 days of age, or year of birth of the foal on the frequency and severity of OC lesions. CONCLUSIONS: Many of the lesions classified as OC, using classification systems described by other authors, were likely to be normal variations of the process of endochondral ossification. Despite the high frequency of such lesions, they were considered to be of minor significance and none were clinically evident. The distribution of lesions was not typical, and most probably reflected the subtlety of the lesions. These results support the hypothesis that Cu is an over-emphasised factor in the aetiopathogenesis of OC. The relationship between subtle macroscopic lesions and lesions resulting in clinical signs of disease requires further investigation.