Partial characterization of bovine salivary proteins by electrophoretic methods.

Electrophoresis in 71/2% polyacrylamide gel separates bovine salivary proteins into 12 bands, and is used as the first step, followed by isoelectrofocusing or electrophoresis in polyacrylamide (15%) gels containing sodium dodecyl sulphate (SDS) or immunoelectrophoresis in two-dimensional separations. Molecular weights of native proteins are determined by electrophoresis on gels of polyacrylamide concentration 10 to 20%. Using these methods, information on native and subunit molecular weights, isoelectric pH values and immunological relationships for bovine salivary proteins has been determined. Enzymic functions for six of the proteins were established by histological methods.

Direct infusion of a variant of insulin-like growth factor-I into the skin of sheep and effects on local blood flow, amino acid utilization and cell replication.

In vivo effects of local infusion of a variant of insulin-like growth factor-I (IGF-I), long-R3-IGF-I, into the skin were investigated using six conscious sheep with food available ad libitum. An artery and vein on the abdominal flank of each animal, as well as the saphenous artery, were catheterized so that infusion of isotopically labelled amino acids, with or without IGF-I, could be used to determine amino acid uptake by arteriovenous difference in combination with blood flow determined by dye dilution. Measurements were made on each animal prior to IGF-I infusion, at hourly intervals for the 4 h of IGF-I infusion into the skin artery, then 2 and 4 h after IGF-I infusion ceased. Numbers of cells replicating in the bulbs of wool follicles in the IGF-I-infused area and in the skin on the contralateral side of each animal were measured after labelling with 5-bromo-2'-deoxyuridine. IGF-I caused a significant increase in the skin blood flow (P < 0.05), utilization of oxygen (P < 0.05), uptake of cysteine (P < 0.05) and phenylalanine (P < 0.001), and the rate of utilization of cysteine (P < 0.05) for protein synthesis. IGF-I increased amino acid uptake regardless of whether the skin was in negative or positive amino acid balance prior to infusion. During the recovery period amino acid utilization by skin returned towards preinfusion levels. No effects of IGF-I were found on replicating cell numbers in the bulbs of wool follicles.

An improved ileal cannula for adult cockerels.

The design of a t-piece ileal cannula and collecting device suitable for long term implantation in adult cockerels, is described. An inner retaining plate sutured to the serosal surface of the ileum prevents expulsion of the cannula while an outer retaining plate prevents the cannula from moving into the abdominal cavity. The cannulae, which were machined from PVC rod, were implanted in 11 cockerels, 10 of which survived in good health for 12 months. Reasons for the failures with earlier designs of cannulae are discussed.

An improved method of ileal cannulation of adult cockerels.

A procedure is described for implanting simple plastic t-piece cannulae made from 1 ml disposable syringes in the terminal ileum of adult cockerels for routine use in digestibility trials. Problems encountered during and after surgery are discussed. Ten of the 15 birds cannulated survived more than nine months.

Effect of food intake on energy and protein metabolism in the skin of Romney sheep.

Sheep fed on either a low (500 g lucern (Medicago sativa) chaff/d; L) or high (1100 g lucerne chaff/d; H) intake had measurements made, using arterio-venous techniques, of blood flow and energy metabolite and cysteine utilization in the skin. Sheep on the H intake had significantly increased skin blood flow (P = 0.014) and oxygen uptake (P = 0.05). Although the H sheep had higher skin blood flow they showed no difference in skin uptake of either glucose or acetate compared with the L sheep, but the H sheep had a significantly lower output of lactate (P = 0.014). Animals in each group had either [14C]glucose or [14C]acetate infused into the skin which showed that acetate was the predominant precursor of skin sterol and fatty acid synthesis in the H sheep while L sheep skin used both glucose and acetate. The H sheep showed an increase in the net uptake of cysteine by the skin (P = 0.053), and in the uptake of cysteine for protein synthesis (P = 0.078), relative to the L sheep and this increase was of a comparable magnitude to the increase in blood flow to the skin. Although blood flow, protein synthesis and energy supply increased in the skin of the H sheep by 200-300%, wool production would only have increased by 10-20%, suggesting that nutrient flux changes are not the sole level of regulation of wool production.

Comparison of several in vivo digestibility procedures to determine lysine digestibility in poultry diets containing heat treated meat and bone meals.

1. Three subsamples of a batch of meat and bone meal (MBM0) were heated at 150 degrees C for 1.5 h (MBM1.5), 3 h (MBM3) or 5 h (MBM5). 2. The MBM's were included in 4 wheat-gluten based diets, each limiting in lysine. 3. The lysine digestibility for each of the diets was determined using precision-fed intact adult cockerels and caecectomised adult cockerels, ileal cannulated adult cockerels, the ileal digesta and excreta of young growing chickens. 4. The results of the digestibility assays were compared with the relative amount of lysine available as determined by growth assay. 5. Comparison of the regression lines of digestible lysine (determined with the digestibility assays) on available lysine (determined by growth assay) indicated that while the magnitude of the digestibility values varied significantly (P less than 0.05) depending on the type of assay used, the differences in lysine digestibility as a result of heat treatment across the 4 diets was the same when comparing assays (the regression lines were parallel). 6. The results of each digestibility assay also correlated with relative digestibility values determined by growth.