A period of 10 weeks of increased protein consumption does not alter faecal microbiota or volatile metabolites in healthy older men: a randomised controlled trial.

Diet has a major influence on the composition and metabolic output of the gut microbiome. Higher-protein diets are often recommended for older consumers; however, the effect of high-protein diets on the gut microbiota and faecal volatile organic compounds (VOC) of elderly participants is unknown. The purpose of the study was to establish if the faecal microbiota composition and VOC in older men are different after a diet containing the recommended dietary intake (RDA) of protein compared with a diet containing twice the RDA (2RDA). Healthy males (74⋅2 (sd 3⋅6) years; n 28) were randomised to consume the RDA of protein (0⋅8 g protein/kg body weight per d) or 2RDA, for 10 weeks. Dietary protein was provided via whole foods rather than supplementation or fortification. The diets were matched for dietary fibre from fruit and vegetables. Faecal samples were collected pre- and post-intervention for microbiota profiling by 16S ribosomal RNA amplicon sequencing and VOC analysis by head space/solid-phase microextraction/GC-MS. After correcting for multiple comparisons, no significant differences in the abundance of faecal microbiota or VOC associated with protein fermentation were evident between the RDA and 2RDA diets. Therefore, in the present study, a twofold difference in dietary protein intake did not alter gut microbiota or VOC indicative of altered protein fermentation.

Regulation of Amino Acid Transporters and Sensors in Response to a High protein Diet: A Randomized Controlled Trial in Elderly Men.

BACKGROUND: The mammalian target of rapamycin complex 1 (mTORC1) is fundamental for many cellular processes, yet it is often dysregulated with aging. Increased amino acid (AA) availability is correlated with the expression of AA transporters (AAT) and mTORC1 activity. Although many AA sensors and mediators have been proposed to relay the AA signal to mTORC1, it has not yet been determined if chronic dietary intervention affects the expression of AAT, sensors and mediators and their relationships with mTORC1 activity. OBJECTIVE AND DESIGN: This study investigated whether the consumption of a diet containing either the current recommended daily allowance (RDA) of protein intake (0.8 g/kg/d) or twice the RDA (2RDA) for ten weeks affected the expression of targets associated with AA transport, sensing and mTORC1 regulation in 26 older men (70-81 years). METHOD: Muscle biopsies were collected before and after the intervention under fasting conditions. Diets were controlled by providing fully prepared meals and snacks. Western blot and quantitative polymerase chain reaction were used to measure protein and gene expression respectively. RESULTS: Consumption of 2RDA reduced the protein expression of L-type amino acid transporter 1 (LAT1). However, plasma leucine concentration and basal mTORC1 activity were unaltered. The downregulation of LAT1 did not affect the expression of AA sensors and mediators, including leucyl tRNA synthetase (LRS), cytosolic arginine sensor for mTORC1 (CASTOR1), Sestrin2 and Rag proteins. Instead, total ribosomal protein S6 (RPS6) was upregulated with 2RDA. CONCLUSION: Ten weeks of 2RDA diet did not affect the fasting mTORC1 signaling, but increased total RPS6 might suggest improved muscular translational capacity to maintain muscular mass.

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.

Effects of quantitative trait loci and the myostatin locus on trace and macro elements (minerals) in bovine liver, muscle and kidney.

A quantitative trait locus (QTL) study of the concentrations of 14 trace and macro elements (minerals) in tissues of beef cattle was conducted in New Zealand. Back-cross calves with Jersey and Limousin ancestry (202 heifers and 211 steers) were generated using first-cross sires. This paper reports on testing for effects of QTL on the concentrations of minerals in liver, kidney and muscle in cattle at slaughter, following a growth phase during which rearing and finishing stages were on pasture. Fifteen QTL were identified (P < 0.05) on a genome-wide basis in combined-sire and within-sire analyses. In addition, the possible effect of the Limousin myostatin F94L allele was tested by fitting each calf's myostatin genotype, and 16 QTL were identified. Twelve were in common with those QTL identified previously, comprising six affecting the liver (copper and zinc, on two chromosomes each; plus iron and molybdenum), three affecting the kidney (calcium, copper and iron), and three affecting muscle (iron, strontium and zinc).

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.

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.

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.

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.

Copper oxide needles administered during early pregnancy improves the copper status of ewes and their lambs.

AIM: To determine the effect of copper oxide (CuO) needles administered orally to ewes in early pregnancy on the copper (Cu) status of ewes throughout gestation and lactation, and of their lambs from birth to weaning. METHODS: In mid-April, after mating, 12 twin-bearing ewes were given an oral capsule containing 5 g CuO needles while 12 others served as untreated controls. Changes in Cu status were monitored by determining serum and liver Cu concentrations on Days 1, 62, 117, 153, 185 and 216 in the ewes, and at 1, 36, 68 and 99 days of age for lambs. Pasture herbage samples were collected at about 60-day intervals for Cu, molybdenum (Mo), iron (Fe) and sulphur (S) determinations. RESULTS: Copper status of the ewe flock was adequate, as initial mean serum and liver Cu concentrations were 15 micromol/L and 1,060 micromol/kg fresh tissue, respectively. The CuO needles did not affect serum Cu concentrations of the ewes or their lambs. Mean serum Cu concentration of all lambs at birth was about half that of ewes (8 vs 17 micromol/L), regardless of Cu supplementation, and not until at least 68 days of age was it similar to the dams'. Liver Cu concentrations of lambs at birth were also lower than that of the ewes (380 vs 640 micromol/kg fresh tissue among the controls), but changed little over time. CuO treatment increased liver Cu concentration in ewes for at least 185 days and in lambs for 36 days (p<0.05). Among untreated ewes, there was a seasonal decline in mean liver Cu concentrations, which were highest in autumn and lowest in early spring (1,060 vs 370 micromol/kg fresh tissue). The mean pasture mineral concentrations were Cu 5.7, Mo 0.48, Fe 194 and S 2,900 mg/kg dry matter (DM). CONCLUSIONS: CuO needles administered to ewes in early pregnancy increased their Cu status through gestation and early lactation, and the Cu status of their lambs for 36 days from birth. Serum Cu concentration was not affected by treatment but a marked rise was observed in all lambs between birth and 10 weeks of age. CLINICAL RELEVANCE: Copper deficiency in young lambs may be conveniently and effectively prevented by treating ewes with CuO needles during early pregnancy. The serum Cu concentration in lambs <8 weeks old may not reflect the Cu status of the flock.

Adding nutritional value to meat and milk from pasture-fed livestock.

Staple meat and milk provide excellent nutrition, but when traditional foods and ingredients are tailored to meet the particular nutritional or lifestyle demands of a population they become even more attractive and valuable. These foods can be considered as delivery systems for health-promoting nutrients. Nutritional improvement of meat and milk can be achieved several ways, preferably by making desirable changes on-farm to directly improve the food without subsequent manipulations. Scope for these changes is limited by animal homeostasis, but alternatives may be less desirable. Methods in vivo that suit typical pastoral farming practice and can complement the solving of animal health and production problems include: selection of traits or phenotypes; specialty diets; long-acting parenteral supplements; and modification of ruminal microflora. Successful techniques to increase the concentration of calcium, selenium, iodine and iron in milk or meat are described. Manipulations to change composition are only one part of bringing tailored foods to market. Commercial realisation of these new products needs the initiative and collaboration of scientists, veterinarians, growers and producers responding to market pull. The uptake of future biotechnologies to capture more value inside the farm gate will also be required if the pastoral industry in New Zealand is to sustain a global competitive advantage.

Growth response to increasing doses of microencapsulated vitamin B12 and related changes in tissue vitamin B12 concentrations in cobalt-deficient lambs.

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.

A reference curve using blood selenium concentration to diagnose selenium deficiency and predict growth responses in lambs.

AIMS: To quantify the relationship between blood selenium (Se) concentration and growth response to Se supplementation in lambs, in order to assess the reliability of current reference ranges and to predict the magnitude of likely responses to supplementation. METHODS: Data from 24 Se-supplementation growth-response trials which used the following general protocol were collated and analysed: in each trial, weaned lambs (n=20-30) were allocated randomly to untreated or to Se-supplemented groups. Supplemented groups received 5 mg Se/month as Na2SeO3 in 20 trials, and 1 mg Se/kg liveweight as BaSeO4 in 4 trials. The duration of the trials was 150-196 days, during which time all lambs were weighed every 4-6 weeks and blood samples were taken at various intervals from 10 lambs/group. RESULTS: Among the 24 trials, flock mean blood Se concentrations of the untreated lambs ranged from 32-569 nmol/l, and growth rate of supplemented lambs was -3 to 63 g/day higher than that of untreated lambs. The relationship between blood Se concentration (X) and growth response (Y) was described by the following hyperbolic-decay equation: Y = -2.6 (SE 3.6) + 1850 (SE 230) / X; (R2=0.74). CONCLUSIONS: For Se-deficient lambs, the potential for a growth response to Se supplementation was strongly related to blood Se concentration. Economically significant liveweight gains of 10 g/day were observed when initial blood Se concentrations were 130 nmol/l. CLINICAL RELEVANCE: Blood Se concentrations can be used to diagnose Se deficiency in lambs and to predict the magnitude of likely growth responses to Se supplementation.

Significance of amount and form of dietary selenium on blood, milk, and casein selenium concentrations in grazing cows.

Organic selenized yeast enriched with selenoamino acids or inorganic sodium selenate (Na2SeO4) was administered per os three times weekly as a drench for 133 d to previously unsupplemented cows that were grazing low Se pastures. Treatment groups received the equivalent of 2 or 4 mg of Se/d of either supplement form. Control cows did not receive a drench. Samples of blood and milk were collected regularly throughout the trial. Selenium concentrations in blood, milk, casein, and liver and glutathione peroxidase activity in blood and liver are reported as responses per milligram of Se intake. Mean blood Se concentrations in treated cows increased steadily and, by d 133, were 4.7 to 8.8 times that in controls. Selenized yeast was 2 to 3 times more effective than was Na2SeO4, and low Se intakes were 27% more efficient per milligram of Se administered than were high Se intakes at increasing milk Se concentration. Casein Se content mirrored that of milk; among all treated and control cows and throughout the trial, the molar ratio of Se in casein as a percentage of the Se in whole milk was constant at 71 +/- 1.2%. The Se concentration in liver biopsies taken on d 133 was indicative of total Se intake during the trial and ranged from 920 to 3920 nmol of Se/kg of fresh weight. These results demonstrate the differing efficacy of organic and inorganic Se dietary supplements to increase dairy cow Se status and to enhance Se content of milk and casein.