Rowett Research Institute

About: Rowett Research Institute is a based out in . It is known for research contribution in the topics: Rumen & Population. The organization has 2986 authors who have published 4459 publications receiving 239472 citations.

New perspectives on the use of tropical plants to improve ruminant nutrition

Abstract: Inadequate nutrition is the main cause of low productivity by ruminants in sub-Saharan Africa. The primary feed resources in the region include natural pasture and crop residues that have tough texture, poor digestibility and are deficient in nutrients. These deficiencies can be corrected by supplementation with high-density feeds such as oilseed cakes and proteins of animal origin. However, protein sources such as oilseed cakes are beyond the economic reach of most farmers, while the incidence of bovine spongiform encephalopathy in Western intensive animal production may be thought to argue against the use of animal proteins. Local tree legumes have been investigated as potential supplements for ruminants because of their beneficial effect of increasing metabolizable energy intake, N intake and feed efficiency, and improving animal performance. However, our work has suggested that some plant materials may have a nutritional value beyond simply their nutrient content, i.e. as rumen-manipulating agents. The foliage of some tree legumes has been shown to be selectively toxic to rumen protozoa. Rumen protozoa ingest and digest bacteria and fungi, degrading their cellular protein to NH3. Microbial protein turnover due to protozoal predation in the rumen may result in the net microbial protein outflow being less than half the total protein synthesized. Results from in vivo experiments have clearly shown that duodenal flow of both undegraded dietary and bacterial protein is generally increased by defaunation. However, no practical method has been developed to date to eliminate protozoa. Anti-protozoal plants may be promising, safe, natural defaunating agents.

Measurement of the rate of protein synthesis in muscle of postabsorptive young men by injection of a 'flooding dose' of [1-13C]leucine.

Abstract: 1. The 'flooding dose' technique for measuring the rate of protein synthesis in tissues in vivo involves the injection of a large amount of unlabelled amino acid together with the tracer to minimize differences in isotopic enrichment of the free amino acid in plasma and tissue compartments. This approach has been investigated in human muscle by taking biopsies from postabsorptive male volunteers given [1-13C]leucine. 2. Intravenous injection of 4 g of unlabelled leucine resulted in a rapid rise in free leucine concentration of seven- to eleven-fold in plasma and five-fold in muscle. Values were still elevated by two-fold after 2 h. 3. Five minutes after injection of [1-13C]leucine (0.05 g/kg) the isotopic enrichment of plasma leucine was 82% that of the injected material, falling to 44% at 120 min. The enrichment of free leucine in sequential muscle biopsies was close to that in plasma and almost identical to that for plasma alpha-ketoisocaproate. 4. The rate of protein synthesis was determined from the increase in leucine enrichment in protein of muscle biopsies taken before and 90 min after injection of [1-13C]leucine (0.05 g/kg; 19 or 39 atom% excess) and the average plasma alpha-ketoisocaproate enrichment over this period (taken to represent muscle free leucine). The mean rate of muscle protein synthesis in 10 subjects was 1.95 (SEM 0.12) %/day. Rates of protein synthesis calculated from plasma leucine as precursor enrichment were only 5% lower than those calculated from plasma alpha-ketoisocaproate.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic acid metabolism in benign and malignant prostatic tissue in vitro: Effects of fatty acids and cyclooxygenase inhibitors

Abstract: Concentrations of fatty acids (FA) in prostatic tissue of patients with either benign or malignant prostatic disease have previously been shown to be significantly different In particular, there was a significant reduction in arachidonic acid (AA, C20:4n-6) and docosapentaenoic acid (DPA, C22:5n-6) concentrations in malignant prostatic tissue (PCa) phospholipids (PL) It was suggested that the decreased AA concentration in PCa may be due to its increased metabolism via the cyclooxygenase (CO) and/or lipoxygenase (LO) pathways to produce eicosanoids such as prostaglandins (PGs) and/or leukotrienes (LTs) rather than an impairment in desaturase activity in situ The eicosanoid production in benign prostatic tissue (BPH) and PCa was determined using [3H]AA The only eicosanoid produced in significant amounts by either tissue was PGE2 and PCa converted radiolabelled AA to PGE2 at an almost 10-fold higher rate than BPH PGE2 production from [3H]AA by PCa was investigated in the presence of oleic acid (OA, C18:1n-9), eicosapentaenoic acid (EPA, C20:5n-3), docosahexaenoic acid (DHA, C22:6n-3), dihomo-gamma-linolenic acid (DGLA, C20:3n-6), eicosatetraynoic acid (ETYA) and ketoprofen (KPN) respectively OA was found to be the most effective inhibitor of PGE2 production by PCa compared with DHA, EPA, ETYA and KPN, while DGLA was the least effective Diacylglycerol (DAG) formation from labelled AA by PCa was about 4-fold greater than in BPH Such high levels of DAG may be a means of promoting tumorigenesis through activation of protein kinase C as found with phorbol esters which can be regarded as DAG analogues

Interconversions and production of volatile fatty acids in the sheep rumen.

Abstract: 1. Sheep fed at a constant rate were infused intraruminally with [1-(14)C]-acetate, -propionate or -butyrate during 5hr. periods. 2. Volatile fatty acids were estimated in the rumen contents and steady-state conditions were obtained. 3. Of the butyric acid carbon 60% was in equilibrium with 20% of the acetic acid carbon, and 2-3g.atoms of carbon were interconverted/day. 4. Little interconversion took place between propionic acid, acetic acid or butyric acid. 5. The net production rates for acetic acid, propionic acid and butyric acid were 3.7, 1.0 and 0.7moles/day respectively. 6. The production of volatile fatty acids accounted for 80% of the animal's energy expenditure.