On the application of compartmental models to radioactive tracer kinetic studies of in vivo protein turnover in animals.

A mathematical framework is presented for unifying and extending the various compartmental models and formulae used to calculate fractional protein synthesis and degradation rates in animals from data obtained by infusing labelled amino acids. It is shown how the various schemes can be derived as special cases of the product-precursor model or some three-pool variant. Three-compartment representations, which circumvent the need to measure the specific radioactivity of the precursor pool, are proposed.

The use of a triploid hybrid for introgression in Lolium species.

Triploid hybrids of Lolium multiflorum (4x) x L. perenne (2x) behaved cytologically as autotriploids but the segregation of isozyme variants did not always agree with the expected trisomic ratios. The overall effect of these deviations from expectation was a greater proportion than expected of diploid progeny from the cross L.

Role of the ovaries in inducing mammogenesis in pregnant pigs.

Ovariectomy, but not removal of the corpora lutea, of gilts at mid-pregnancy delayed the onset of lobulo-alveolar development in the mammary glands. Lactogenesis at the time of parturition was delayed by both ovariectomy and removal of the corpora lutea.

The digestion of perennial ryegrass (Lolium perenne cv. Melle) and white clover (Trifolium repens cv. Blanca) by grazing cattle.

1. Pure swards of perennial ryegrass (Lolium perenne cv. Melle) as a primary growth (May), trimmed primary growth (early June) and regrowth (late June), and white clover (Trifolium repens cv.

Digestibility of pentose sugars and uronic acids and their effect on chick weight gain and caecal size.

1. In the first experiment D-xylose, L-arabinose, D-galacturonic and D-glucuronic acids were fed ad libitum to young chicks for 2 weeks at 200 g/kg of diet and weight gains and food consumption were recorded. 2.

Biochemical indicators of fatness in meat-type chickens: lack of correlation between lipoprotein lipase activity in post-heparin plasma and body fat.

1. Possible relationships between fatness and lipoprotein lipase activity in adipose tissue and plasma from heparinised birds were examined in 7-week-old male and female broilers. 2.

Energy and nitrogen retention and loss in broiler chickens genetically selected for leanness and fatness.

1. A breeding programme based on the assessment of the body fat content of broilers by measurement of plasma very low density lipoprotein concentration has resulted in 2 lines with significantly different body fat contents. 2.

Energy expenditure and physical activity in domestic fowl kept on standard and interrupted lighting patterns.

1. The energy expenditure (H) and physical activity of laying hens were measured under lighting regimes of 14L:10D (standard), 2L:10D:2L:10D (interrupted) and (15 X (13 min L:47 min D]: 9D (fragmented). 2.

Effects of age and of early lighting on ovarian function in breeding turkeys.

1. Yellow follicle numbers and production of defective egg shells were greater in the early part of the laying period in conventionally-reared turkeys photostimulated at 24 rather than 30 weeks of age. 2.

Influence of goat's-milk folate-binding protein on transport of 5-methyltetrahydrofolate in neonatal-goat small intestinal brush-border-membrane vesicles.

1. The influence of goat's-milk folate-binding protein (FBP) on the uptake of 5-methyltetrahydrofolate (MTHF) by brush-border-membrane vesicles prepared from the small intestine of the 6-d-old goat was investigated using a rapid-filtration assay. 2.

Maintenance energy requirements of laying hens: a comparison of measurements made by two methods based on indirect calorimetry.

1. The aims of this study were to compare maintenance metabolisable energy requirement estimates obtained in laying hens by two methods of respiration calorimetry, to investigate the changes in the heat production and energy retention of laying hens associated with temporarily reduced energy intake and to demonstrate the errors caused by using inappropriate values of net efficiency of energy utilisation (k) when extrapolating to maintenance energy requirement from a range of energy retention values. 2.

Nutrient sensitivity of gastric emptying of digesta in the preruminant calf.

1. Studies of gastric function were made in preruminant calves fitted with a single abomasal cannula, re-entrant cannulas in the duodenum close to the pylorus and recording electrodes on the pyloric antrum and proximal duodenum. 2.

Rates of eating by domestic fowls in relation to changing food deficits.

Rates of eating by immature female fowls declined in a curvilinear way in the 30 min after return of food after 0-4 h deprivation. Amounts eaten in the first 5-10 min were related positively to the length of deprivation and were greater with pelleted food than with mash. Times taken by birds to reach a presumed equilibrium between probabilities of feeding starting and stopping, at two consecutive minutes with less than 0.

The incidence of ectopic cartilaginous and osseous lung nodules in young broiler fowls with ascites and various other diseases.

The incidence of ectopic cartilaginous and osseous lung nodules in young broiler fowls with ascites and various other diseases has been determined. In all groups of diseased birds there were more nodules in the lungs compared with control birds. The birds that died with an ascitic syndrome had a significantly greater number of nodules than the other groups of diseased birds, with significantly more occurring in the left lung than in the right (P<0.

A rumen anaerobic fungus of the genus Neocallimastix: ultrastructure of the polyflagellate zoospore and young thallus.

The ultrastructure of the zoosporic, rumen fungal anaerobe, Neocallimastix sp. R1, was determined and compared to that of the two known species of Neocallimastix. Zoospores of the new isolate were generally ovoid in shape, but without the waisted appearance of N.

The fermentative characteristics of anaerobic rumen fungi.

Substrate utilization and fermentation characteristics of rumen fungi of the genus Neocallimastix are described. Preliminary observations on the removal of monosaccharides from plant cell walls and the effect of fermentation products on growth of Neocallimastix sp. (isolate R1) are presented.

Haematological and tissue abnormalities in chicks caused by acute and subclinical folate deficiency.

1. Haematological, histological and ultrastructural findings in young chicks fed on a purified diet severely deficient in folate are reported. 2.

Muscle growth and protein degradation during early development in chicks of fast and slow growing strains.

1. Growth of breast and leg muscles and excretion of N tau methyl histidine in layer (slow growing) and broiler (fast growing) chicks were measured at five time intervals between 2 and 33 days of age. 2.

Observations on the size of the follicular hierarchy in the turkey hen and a case of arrested follicular growth.

1. The phase of rapid development of ovarian follicles in turkeys fed ad libitum or given a restricted allocation of food from 6 to 30 weeks of age was determined by feeding a fat soluble dye and counting the number of rings of dye in the yolks of laid eggs. 2.

A comparison of the antigenicity of soya-bean-based infant formulas.

1. The antigenicity of four soya-bean-based infant formulas (Prosobee powder, Prosobee liquid concentrate (Mead Johnson, Uxbridge, Middx), Wysoy (Wyeth, Maidenhead, Berks) and Formula S (Cow and Gate, Trowbridge, Wilts] was measured by enzyme-linked immunosorbent assays (ELISAs) specific for glycinin and beta-conglycinin. Results were compared with in vivo assessments of antigenicity using guinea-pigs, rabbits and calves.

Collagen and non-collagen protein turnover in skeletal muscle of growth hormone-treated lambs.

Long-term administration of GH to normal, well-fed lambs caused a significant increase in net muscle growth. This could be accounted for by increased rates of muscle protein synthesis, although red and white muscles responded differently. The increased rate of protein synthesis was due to an increased protein synthetic capacity (increased muscle RNA content) but efficiency per unit of RNA also tended to increase in red muscle.

Ovarian follicular structure of White Leghorns fed ad libitum and dwarf and normal broiler breeders fed ad libitum or restricted until point of lay.

1. Yellow follicle numbers when the first egg was laid were 6.3, 9.