Distribution of prion protein genotypes in breeds of sheep in New Zealand.

AIM: To use an established high through-put genotyping procedure to gain an estimate of the frequency of alleles of the prion protein (PrP) gene in some common sheep breeds in New Zealand. METHODS: Using a genotyping procedure based on matrix-assisted laser desorption ionisation-time of flight (MALDI-TOF), DNA samples from 3,024 sheep from New Zealand, including breeds such as Romney, Texel, Coopworth, Merino and mixed breed, were isolated, genotyped and the results analysed. RESULTS: The 15 scrapie genotypes commonly reported, and derived from the five commonly reported allelic variants (ARR, ARQ, AHQ, ARH and VRQ), were all observed in the samples analysed. The estimates were indicative of the frequencies in the population of alleles present in breeds of sheep in New Zealand. There was a significant difference between the frequencies of alleles between breeds, but the ARQ, followed by the ARR allele, were, except in Carwell sheep, the most common alleles present. CONCLUSION: This study gave an indication of the percentages of PrP gene alleles in sheep in New Zealand, including data previously unreported from breeds in this country. It is of interest because of the relatively large size of the sheep population in New Zealand compared with many countries, and it provides some useful information on the genetic susceptibility or resistance of the sheep population in New Zealand to scrapie. The frequencies of the alleles can be different for an individual breed compared between countries.

Genotypic effects of calpain 1 and calpastatin on the tenderness of cooked M. longissimus dorsi steaks from Jersey x Limousin, Angus and Hereford-cross cattle.

Single nucleotide polymorphisms (SNPs) in the calpain 1 (CAPN1) and calpastatin (CAST) genes were studied to determine their effects on meat tenderness in Bos taurus cattle. Strip loins (M. longissimus dorsi) were removed from cattle in four resource populations after slaughter (n = 1042), aged under controlled conditions until fixed times after rigor mortis, cooked and measured using a tenderometer. Animals were genotyped for the CAPN1 SNP c.947C>G (p.Ala316Gly; AF252504) and for the CAST SNP c.2959A>G (AF159246). Frequencies of CAPN1 C alleles ranged from 23% to 68%, and CAST A alleles from 84% to 99.5%. From all data combined, the CAPN1 CC genotype (compared with the GG genotype) was associated with a 20.1 +/- 1.7% reduced average shear force at intermediate stages of ageing (P < 0.001) and with a 9.5 +/- 1.3% reduction near ultimate tenderness (P < 0.001). The heterozygote was intermediate. For CAST, corresponding values for AA compared with AG genotypes were reductions of 8.6 +/- 2.0% and 5.1 +/- 1.6% respectively (both P < 0.001), but there were too few GG genotypes for comparison. There were small interactions between the CAPN1 and CAST genotypes. For the CAPN1 and CAST genotypes combined, the maximal genotype effect in average shear force was 25.7 +/- 5.5% (P < 0.001) at intermediate stages and 15.2 +/- 4.8% near ultimate tenderness (P < 0.01).

Noradrenergic regulation of hypothalamic cells that produce growth hormone-releasing hormone and somatostatin and the effect of altered adiposity in sheep.

The growth hormone (GH) axis is sensitive to alteration in body weight and there is evidence that central noradrenergic systems regulate neurones that produce growth hormone-releasing hormone (GHRH) and somatostatin (SRIF). This study reports semiquantitative estimates of the noradrenergic input to neuroendocrine GHRH and SRIF neurones in the sheep of different body weights. We also studied the effects of altered body weight on expression of dopamine beta-hydroxylase (DBH), the enzyme that produces noradrenalin from dopamine. Ovariectomised ewes were made Lean (39.6 +/- 2.6 kg; Mean +/- SEM) by dietary restriction, whereas Normally Fed animals (61.2 +/- 0.8 kg) were maintained on a regular diet. Brains were perfused for immunohistochemistry and in situ hybridisation. The Mean +/- SEM number of GHRH-immunoreactive (-IR) cells was lower in Normally Fed (65 +/- 7) than in Lean (115 +/- 14) animals, whereas the number of SRIF-IR cells was similar in the two groups (Normally Fed, 196 +/- 17; Lean 230 +/- 21). Confocal microscopic analysis revealed that the percentage of GHRH-IR cells (Normally Fed 36 +/- 1.5% versus Lean 32 +/- 4.6%) and percentage of SRIF-IR cells (Normally Fed 30 +/- 40.4% versus Lean 32 +/- 2.3%) contacted by noradrenergic fibres did not change with body weight. FluoroGold retrograde tracer injections confirmed that noradrenergic projections to the arcuate nucleus are from ventrolateral medulla and noradrenergic projections to periventricular nucleus arise from the ventrolateral medulla, nucleus of solitary tract, locus coeruleus (LC) and the parabrachial nucleus (PBN). DBH expressing cells were identified using immunohistochemistry and in situ hybridisation and the level of expression (silver grains/cell) quantified by image analysis. The number of DBH cells was similar in Normally Fed and Lean animals, but the level of expression/cell was lower (P < 0.02) in the PBN and LC of Lean animals. These results provide an anatomical basis for the noradrenergic regulation of GHRH and SRIF cells and GH secretion. Altered activity or noradrenergic neurones in the PBN and LC that occur with reduced body weight may be relevant to the control of GH axis.

A comparison of biochemical and meat quality variables in red deer (Cervus elaphus) following either slaughter at pasture or killing at a deer slaughter plant.

To investigate effects of pre-slaughter handling on blood and muscle biochemistry and venison quality, paddock-shot (n=8) and commercially slaughtered red deer (n=8) were compared. The deer were kept in two larger groups. One stag per group per day was head-shot, exsanguinated, electrically stimulated then transported 150 m to a deer slaughter premises (DSP) for processing. Prior to each slaughter day one of the groups was mustered into a deer yards and six (including two experimental) deer were selected for commercial handling and processing (including electrical stimulation) at the same DSP. Blood samples taken during exsanguination showed higher levels of cortisol, progesterone, glucose, lactate, albumin, creatine kinase, lactate dehydrogenase, aspartate aminotransferase and packed cell volume in the DSP-killed deer compared with the paddock-shot deer (P<0.05). Interpretation of these values indicated that pre-slaughter handling created moderate stress and high levels of muscular exertion or damage, possibly related to antagonism during lairage. However muscle glycogen, pH and meat quality measurements showed only minor, muscle-specific differences between treatments.

Variation in antral follicle development during the follicular phase of the oestrous cycle in red deer (Cervus elaphus) hinds.

The aim of this study was to quantify antral follicle populations in cyclic red deer hinds and to monitor follicle development leading to ovulation. Oestrus was synchronized with exogenous progesterone and ovaries were recovered approximately 0, 12, 24 or 36 h (follicular phase) or 10 days (luteal phase) after progesterone withdrawal (n = 5 per group). All follicles > or = 2 mm in diameter were dissected out, health status was assessed, follicular fluid oestradiol content was measured, granulosa cells were harvested and their capacity for oestradiol and cAMP production was determined. The time of oestrus and the preovulatory LH surge were monitored in five control hinds. Deer ovaries contained 26.6 +/- 3.45 (mean +/- SEM) follicles > or = 2 mm in diameter (range 4-81), with at least one large antral follicle (diameter: 8.3 +/- 0.38 mm) per hind. There was a strong correlation between follicle size and granulosa cell population (r(2) = 0.676). Approximately half (50.7%) of the follicles were classified as healthy, with the percentage classified as atretic decreasing with increasing follicle size. Neither the total number of antral follicles nor their size distribution differed significantly among groups. There were significantly more (P < 0.05) healthy follicles at 24 h after progesterone withdrawal than at 0 h, when large oestrogenic follicles had fewer granulosa cells, lower follicular fluid oestradiol concentrations and lower aromatase activity (P < 0.05) than did those from other groups. In summary, antral follicle development in red deer is similar to that in other monovulatory ruminants, and at least one large follicle is present at all stages of the oestrous cycle.

Identifying infertile homozygous Inverdale (FecXI) ewe lambs on the basis of genotype differences in reproductive hormone concentrations.

Introduction of the Inverdale prolificacy gene (FecXI) could markedly improve reproductive efficiency in commercial flocks, but as homozygous carrier Inverdale ewes are infertile, it is imperative that these animals are identified at an early age and excluded from breeding stock. As the ovaries of homozygous carrier ewes are nonfunctional, there are wide differences in reproductive hormone levels between these and other Inverdale genotypes. This study assesses the accuracy of using hormone concentrations alone, to identify infertile homozygous ewe lambs. Ewe lambs were blood sampled at 2, 5 and/or 8 months of age, and plasma analyzed for follicle-stimulating hormone (FSH), luteinizing hormone (LH) and inhibin content. These animals were either the offspring of both known carrier rams and known carrier ewes, and therefore would be either homozygous (II) or heterozygous (I+) for the Inverdale gene (group 1, N = 122), or had one parent that was a carrier and therefore would be either heterozygous or noncarriers (++) of the gene (group 2, N = 32). Animals were designated as either II or I+/++ on the basis of their plasma hormone concentrations. Inverdale genotype was also assigned from laparoscopic observation of the ovaries at each of these occasions. Definitive assignment of genotype was made at laparoscopy as adults during the breeding season. On the basis of laparoscopy as adults, 62 (51%) lambs in group 1 were identified as homozygous and 60 (49%) as heterozygous. At all three ages, both mean FSH and mean LH concentrations were significantly higher in II than in I+ lambs. Mean inhibin concentrations were significantly lower in II lambs at 8 months, but did not differ significantly between genotypes at 2 or 5 month of age. The use of discriminant analysis techniques to segregate individual animals in group 1 on the basis of their plasma FSH and LH concentrations, correctly identified Inverdale genotype in 50/52 (96%) lambs at 2 months, 75/79 (95%) at 5 months and 118/122 (97%) at 8 months of age. Discriminant analysis was equally effective for segregating II ewe lambs (group 1) from fertile ewe lambs of I+ and ++ genotype (group 2, 97% correct at 5 months and 98% at 8 months). At no stage did inclusion of inhibin concentrations into the discriminant function alter the number of homozygous ewes misclassified. This demonstrates that infertile homozygous ewe lambs can accurately be distinguished from their fertile flockmates by using plasma concentrations of gonadotrophins alone, and that this can be achieved from as early as 2 months of age.

Effect of melatonin implants on secretion of luteinizing hormone in intact and castrated rams.

Rams were treated with melatonin implants in 2 experiments designed to examine the control of reproductive seasonality. In Exp. 1, rams (n = 12) were allocated to 3 treatment groups: 2 groups were treated with 2 melatonin implants per ram for 4 months from 11 November (N) and 9 December (D) and the remaining group was untreated (C). The seasonal increase in luteinizing hormone (LH) pulse frequency and testes size was advanced in Groups N and D. A second seasonal cycle in LH secretion and testes size occurred in Groups N and D after melatonin implants became exhausted. In Exp. 2, rams (n = 20) were allocated to 4 treatment groups: 10 rams were castrated on 6 October and 1 group of entire rams (EM) and one group of castrated rams (CM) were treated with 2 melatonin implants per ram each month from 3 November until 8 January. The other group of entire rams (EC) and castrated rams (CC) was untreated. An increase in LH pulse frequency occurred after castration. Melatonin treatment increased LH pulse frequency in entire rams and reduced LH pulse frequency in castrated rams. The results demonstrated that the advanced reproductive development as a result of treatment with melatonin implants was due to an effect of melatonin on the hypothalamic pulse generator to increase LH pulse frequency. The ability of melatonin to influence LH pulse frequency in entire and castrated rams indicated that an effect of melatonin on the hypothalamic pulse generator is independent of testicular steroids.

Influence of food intake but independence of body weight on puberty in female sheep.

The effect of maintaining female sheep at a body weight intermediate between the normal weight for puberty (30-35 kg) and 20 kg (puberty suppressed) on the onset of oestrous cycles was studied. In addition, the influence of ad-libitum food intake or insulin infusion was studied in animals previously maintained at 20 kg. Coopworth ewe lambs (10 weeks old) were allocated to one of 6 treatments: (A) ad-libitum fed (n = 6), (B) ad-libitum fed to 28 kg then maintained at that weight (n = 6), (C) ad-libitum fed to 24 kg then maintained at that weight (n = 6), (D) maintained at 20 kg until Week 29 and then fed ad libitum (n = 6), (E) maintained at 20 kg and infused with 0.1 U insulin/kg/24 h for 2 weeks from 29-31 weeks of age (n = 5), (F) maintained at 20 kg (n = 6). The lambs were penned indoors under natural photo-period, which was decreasing virtually throughout the study, and fed a pelleted concentrate diet which was recorded daily. They were blood sampled twice a week, and plasma was analysed for progesterone. Puberty was defined as the date when plasma concentrations of progesterone first exceeded 1 ng/ml. In addition, ewes in Groups D, E and F were blood sampled every 10 min for 8 h on Days 0 and +12 of the insulin infusion or access to ad-libitum feeding and the plasma was analysed for luteinizing hormone (LH).(ABSTRACT TRUNCATED AT 250 WORDS)

The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. 4. Sites of carbohydrate and protein digestion as influenced by dietary reactive tannin concentration.

1. Vegetative secondary growth Lotus pedunculatus was cut daily, and fed fresh at hourly intervals (600 g dry matter (DM)/d) to three groups each of three sheep fitted with permanent cannulas into the rumen and duodenum. Lotus fed to two of the groups was sprayed with low and high rates of polyethylene glycol (PEG; molecular weight 3350), which specifically binds the condensed tannins (CT). Nutrient intake and faecal excretion were measured directly, duodenal flows estimated from continuous intraruminal infusion of inert ruthenium phenanthroline (Ru-P) and CrEDTA markers, and rumen pool sizes measured at slaughter. 2. Dietary concentrations of total reactive CT (i.e. that not bound to PEG) were 95, 45 and 14 g/kg DM, whilst the corresponding values for free CT were 15, 5 and 2 g/kg DM. 3. Increasing dietary reactive CT concentration linearly increased duodenal flows of non-ammonia nitrogen, but linearly decreased the apparent digestibility of energy and organic matter, and rumen digestion of hemicellulose but not of cellulose. Rumen digestion as a proportion of total digestion was increased by the higher PEG rate for organic matter, energy, pectin and lignin. 4. High dietary CT concentration was associated with increased N retention. Rumen ammonia concentration and pool size showed only a slight decline on this diet, indicating that there must have been increased recycling of N into the rumen. 5. Increasing dietary reactive CT concentration had no effect on the rate at which carbohydrate constituents were degraded in the rumen per unit time (FDR), but increased the rate at which their undegraded residues (FOR) left the rumen per unit time. The latter appeared to be the principal mechanism by which rumen digestion as a proportion of total digestion was reduced at high dietary CT concentrations. From a comparison of FDR and FOR of carbohydrate components in lotus and Brassica oleracea diets, it was concluded that hemicellulose digestion was rate-limiting for rumen cell-wall digestion, probably due to bonding with lignin. However, the considerable post-rumen digestion of hemicellulose was not associated with post-rumen lignin digestion. 6. It was concluded that a desired concentration of CT in Lotus sp. should represent a balance between the positive effect of CT in improving the efficiency of N digestion and their negative effect in depressing rumen carbohydrate digestion. A recommended concentration is 30-40 g/kg DM.

Responses to oral methionine supplementation in sheep fed on kale (Brassica oleracea) diets containing S-methyl-L-cysteine sulphoxide.

1. Responses to twice-weekly oral supplementation with 4.0 g methionine were measured with lambs (27 kg) grazing kale (Brassica oleracea) for 10 weeks (Expt 1). In a second experiment with sheep fed on kale at hourly intervals, rumen fractional outflow rates of CrEDTA and ruthenium Tris(1,10 phenanthroline) markers were measured from the rates of decline in their concentrations. Rumen turnover of S-methyl-L-cysteine sulphoxide (SMCO) and of carbohydrate (CHO) constituents were also measured. The kale fed contained 11.4 g SMCO/kg dry matter and the ratio, readily-fermentable: structural CHO was high at 2.9. 2. Severe haemolytic anaemia, associated with low live-weight gain (LWG), occurred in the lambs during the initial 5 weeks of grazing, due to rumen fermentation of SMCO. Oral methionine supplementation raised plasma concentrations of methionine and cysteine, increased wool growth rate, and increased LWG during the initial 5 weeks. Methionine supplementation also increased rumen pool and plasma SMCO concentrations, suggesting reduced rumen SMCO fermentation. 3. In Expt 2, rumen degradation rate of SMCO (1.2/h) was calculated to be twice as fast as that of the most rapidly fermented dietary CHO constituents and eight times faster than the rate of water outflow (0.16/h), thus explaining its virtually complete rumen degradation and toxicity in brassica diets. It was estimated that 1.2 g of each 4.0 g methionine administered would have escaped rumen degradation, due to the high rate of water outflow from the rumen. 4. Disappearance rates of CHO constituents from the rumen were as predicted for normal ruminant diets, showing that rumen metabolism of SMCO did not have a depressive effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Glucose and protein metabolism during late pregnancy in triplet-bearing ewes given fresh forages ad lib. 1. Voluntary intake and birth weight.

Ewes of the Booroola X Romney genotype carrying triplet lambs were given fresh forages ad lib. in late pregnancy. In Expt 1, groups of three ewes were given kale (Brassica oleracea), perennial ryegrass (Lolium perenne) or perennial ryegrass (0.75)-barley (0.25). In Expt 2, groups of two or three ewes were given fresh perennial ryegrass and infused into the abomasum with iso-energetic quantities of casein and glucose in a 2 x 2 factorial arrangement. Post-lambing ewe live weights were 40-50 kg. Glucose irreversible loss (GIL) was determined from dilution of D-[U-14C]glucose. For ewes given kale, perennial ryegrass and perennial ryegrass-barley in Expt 1, mean metabolizable energy (ME) intakes were 0.50, 0.82 and 0.83 MJ/kg live weight 0.75 per d, GIL was 112, 142 and 157 g/d, and mean birth weight 2.22, 3.05 and 2.95 kg/lamb. In Expt 2, infusion of glucose, casein, and glucose + casein depressed herbage ME intake respectively by 1.6, 0.9 and 0.3 times the amount of ME infused. GIL (185-325 g/d) was increased by 800 and 350 g respectively for each kg of glucose or casein infused. Casein infusion increased calculated amino acid absorption from 0.18 to 0.36 of ME, increased wool growth and increased calculated maternal N balance. Birth weight was unaffected by nutritional treatment and averaged 3.29 kg/lamb. When values from both experiments were combined, birth weight was related to GIL by a hyperbolic relation, with maximum predicted birth weight being 4.1 kg/lamb. It was postulated that this value was never attained in practice, due to uterine expansion being restricted by the low maternal body size. Marked decreases in birth weight occurred when GIL decreased below 173 g/d. It was calculated that ewes in all treatment groups were in negative energy balance, and that glucose supplied by the kale and unsupplemented ryegrass diets were respectively below and equal to calculated conceptus uptakes of glucose necessary to maintain growth of triplet fetuses. It was further calculated that amino acid requirements of triplet-bearing ewes in late pregnancy were likely to exceed substantially net absorption from digestion of fresh forage diets, and that maternal tissues go into negative N balance to ensure fetal growth, thus explaining the lack of response to abomasal casein infusion.

Endocrine regulation of metabolism in sheep given kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trifolium repens) fresh-forage diets.

Diets of fresh kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trifolium repens) herbage were fed to growing sheep in three experiments. In Expts 1 and 3 the sheep were confined indoors and fed at hourly intervals, and all were given supplementary iodine to counteract kale goitrogens. Lambs grazed the two forages for 24 weeks in Expt 2, with and without intramuscular injections of iodized oil. The kale and herbage contained respectively 11 and less than 0.1 g S-methyl-L-cysteine sulphoxide (SMCO)/kg dry matter (DM) and values for readily fermentable: structural carbohydrate (CHO) were 3.1 and 0.8, respectively. Blood samples were withdrawn from indwelling catheters (Expts 1 and 3) or venipuncture (Expt 2) and the plasma analysed for a range of hormones using radioimmunoassay procedures. Glucose irreversible loss (GIL) was measured in Expt 1 using primed continuous infusions of D-[U-14C]glucose. Samples of adipose tissue were removed from the shoulder area in Expt 3, and rates of D-[U-14C]glucose and [U-14C]acetate incorporation and oxidation were measured in vitro, together with the rate of glycerol release. In the presence of supplementary I2, kale feeding was associated with an elevation in plasma concentration of free thyroxine (T4). Regardless of I2 supplementation, sheep fed on kale had much higher plasma growth hormone concentrations than sheep fed on ryegrass-clover herbage, and this was accompanied by reduced plasma somatostatin concentrations. Plasma insulin and glucagon concentrations were similar for sheep fed on the two diets; GIL tended to be slightly but not significantly greater (9.4%) for sheep fed on kale than for those fed on ryegrass-clover herbage.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of oxfendazole in red deer (Cervus elaphus).

The pharmacokinetics of oxfendazole (OFZ) in red deer (Cervus elaphus) was examined. OFZ, administered per os at 4.53 mg kg-1, was extracted in ether from plasma and identified and concentrations estimated by high pressure liquid chromatography. Irrespective of whether the animals were fed concentrates indoors as pellets or grass while on pasture, OFZ was absorbed rapidly. Concentrations of OFZ in plasma reached maxima within 20 hours (0.83 and 1.005 mg litre-1 respectively) and were undetectable 36 hours after administration. Fenbendazole was not detected at any time in the chromatograms. Metabolism of OFZ occurred rapidly producing the sulphone metabolite. In comparison with published data for OFZ in sheep, red deer appear to metabolise OFZ and excrete OFZ sulphone at much faster rates. Consequently, anthelmintic efficacy is likely to vary from species to species.

The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. 2. Quantitative digestion of carbohydrates and proteins.

Primary growth vegetative Lotus pedunculatus containing 46 and 106 g/kg dry matter (DM) of total condensed tannin and 3 and 14 g/kg DM of free condensed tannin, was cut and fed fresh at hourly intervals (750 g DM/d) to sheep fitted with permanent cannulas into the rumen and duodenum. Low- and high-tannin lotus contained respectively 41.3 and 31.6 g total nitrogen/kg DM and 132 and 152 g lignin/kg DM. The two forms of lotus were similar in carbohydrate composition. Nutrient intake was recorded and faecal output measured by direct collection. Digesta flow to the duodenum was estimated by measuring dilution at the duodenum of inert ruthenium phenanthroline (Ru-P) and chromium-EDTA markers continuously infused into the rumen. Effects attributable to condensed tannins were assessed by comparing the digestion of the two diets, and by comparing the digestion of each with predicted values for non-tannin-containing fresh forages fed at similar intakes. Apparent digestibility of all nutrients measured was less for high- than for low-tannin lotus (P less than 0.01). The levels of cellulose digested ruminally and post- ruminally in both forms of lotus were similar to predicted values. However, less hemicellulose and readily fermentable carbohydrate (RFC; soluble carbohydrate + pectin) was digested in the rumen in sheep given both forms of lotus than would be predicted for non-tannin-containing fresh forage diets, but this was compensated for by greater post-ruminal absorption of both nutrients. Total N gains across the rumen (duodenal N flow--total N intake) were 1.8 and 10.5 g/d for low- and high-tannin lotus v. predicted losses of 3.7 and 2.1 g/d for non-tannin-containing fresh forages given at the same total N intakes. Post-ruminal digestion of non- amonia -N (NAN; proportion NAN flowing at duodenum) was 0.71 and 0.67 for low- and high-tannin lotus respectively v. 0.76 for comparable non-tannin-containing fresh forages. Energy absorbed as amino acids from the small intestine was calculated to be 0.29 of metabolizable energy for both forms of lotus, compared with 0.17 and 0.21 for perennial ryegrass and white clover. It was concluded that the presence of condensed tannins in lotus markedly increased post-ruminal NAN absorption compared with non-tannin-containing fresh forage diets, but depressed ruminal digestion of RFC and hemicellulose.

Protein metabolism in growing lambs given fresh ryegrass (Lolium perenne)--clover (Trifolium repens) pasture ad lib. 2. Endocrine changes, glucose production, and their relationship to protein deposition and the partition of absorbed nutrients.

1. Glucose metabolism and changes in the concentrations of several hormones in jugular plasma were measured in growing lambs fed on fresh pasture ad lib. One group of lambs acted as control while the second received a continuous abomasal infusion supplying 44 g sodium caseinate+0.5 g L-methionine/d. 2. Hormone concentrations were determined by radioimmunoassay procedures and glucose irreversible loss measured from continuous infusion of D-[U-14C]glucose. 3. Protein infusion increased plasma concentrations of insulin, glucagon and thyroxine (T4), depressed those of growth hormone, prolactin and somatostatin and had no effect on triiodothyronine (T3) concentrations. Cortisol concentrations also tended to be slightly higher in the plasma of protein-infused lambs. 4. Increases in herbage intake within the ad lib, range were associated with increases in plasma insulin and glucagon concentrations and decreases in growth hormone concentration, and it is suggested that these effects could be mediated in part by the accompanying increases in protein absorption from the intestines. The T4:T3 value also decreased with increasing herbage intake, and it is suggested this was due to conversion of T4 to T3. 5. After correction by covariance to equal herbage intake, rates of irreversible glucose loss for control and protein-infused lambs were 9.2 and 10.0 mg/min per kg body-weight 0.75. It was calculated that respectively 0.12 and 0.19 of the total glucose production in control and protein-infused lambs could be accounted for by net synthesis from protein. 6. It was concluded that changes in the circulating concentration of several hormones in protein-infused compared with control lambs were likely to have been implicated in protein deposition forming a greater proportion of energy retention in the infused lambs (0.41 v. 0.27).

A multi-station machine for the fatigue testing of denture base materials.

A multi-station machine has been designed and built to determine the resistance to fatigue failure of denture base materials. The machine has enabled complete S-N curves to be plotted for conventional and reinforced denture base materials involving many megacycles of operation. The resistance to fatigue failure of conventional denture base polymers is similar to that of 'Perspex'; that of PMMA reinforced with carbon fibre is of an order of magnitude greater.