Effect of enzyme supplementation of a rye-based diet on xylanase activity in the small intestine of broilers, on intestinal crypt cell proliferation and on nutrient digestibility and growth performance of the birds.

1. A study was undertaken to investigate the susceptibility to peptic digestion of exogenous xylanase (EC 3.2.1.8) from Trichoderma longibrachiatum, added to a rye-based diet for broiler chickens, in order to elucidate its possible site of action. 2. It was also designed to investigate the effects of the enzyme (plus exogenous protease EC 3.4-24.28) when added to a rye-containing diet (60% rye/kg diet) on crypt cell proliferation in the mucosa of the small intestine, on short chain fatty acid (SCFA) concentrations in the small intestine digesta and in portal blood and on nutrient digestibilities. 3. In Experiment 1, the enzymes were added at activities 10x and 30x those recommended in commercial practice, but in Experiment 2 the activities were the recommended levels. 4. A significant proportion (estimated to be 15 to 20%) of the xylanase added at the higher concentration (15,000 and 45,000 units/kg diet) remained active in the small intestine of the growing chicken. 5. The crypt cell proliferation rate in birds fed on the control diet (45 cells/2 h) was significantly higher than in birds fed on the diets supplemented with enzyme at the higher level (29 and 33 cells/ 2 h), but there was no significant effect on SCFA. In birds fed on the diet supplemented with enzyme at the commercial level there was no clear-cut effect on crypt cell proliferation but exogenous xylanase could be detected in the small intestine. Intestinal fluid viscosity was reduced and growth performance of the birds was improved by the supplementation with exogenous enzymes. 6. Part of the improvement in growth performance could be ascribed to a 25% increase in the digestibility of nitrogen and a doubling of the digestibility of fat.

Growth, viscosity and beta-glucanase activity of intestinal fluid in broiler chickens fed on barley-based diets with or without exogenous beta-glucanase.

1. Three groups of birds were fed for up to 35 days on diets containing 500 g barley (cv. Condor)/kg diet, with or without exogenous beta-glucanase, either a commercial preparation or a recombinant endoglucanase. 2. Birds which received diets containing the exogenous enzymes grew faster for the first 3 weeks but after that there was no apparent difference in rate of growth. 3. beta-Glucanase activities in the crop and small intestine of birds given exogenous enzymes were generally higher than those of birds given only the basal diet. 4. Viscosity of intestinal fluid in birds given only the basal diet decreased with age but there was no corresponding increase in beta-glucanase activity. This discounts bacterial beta-glucanase as a contributory factor in the adaptation to beta-glucanase apparent in older birds.

A comparison of several published methods for barley anther culture.

A number of methods have been published for barley (Hordeum vulgare L.) anther culture and have gained acceptance in different laboratories. The breeder's requirement is for a compromise method that gives good, repeatable results for a wide range of genotypes. Yet the routine production of spontaneously doubled haploid green regenerants remains difficult. Despite attempts to formulate a widely-applicable anther culture method, the 4 main published methods, compared here with one modified procedure, are quite distinct for a number of important characteristics. The methods interacted strongly with the 3 genotypes, and response ranged from zero to 28 green regenerants per 100 anthers plated. The current methods still require often substantial modification to suit local situations in order that the technology may be exploited by barley breeders.

Degradation of glucosinolates during in vitro incubations of rapeseed meal with myrosinase (EC 3.2.3.1) and with pepsin (EC 3.4.23.1)-hydrochloric acid, and contents of porcine small intestine and caecum.

Changes in the concentrations of glucosinolates from rapeseed meal and some glucosinolate degradation products during incubation in vitro with myrosinase (EC 3.2.3.1), with pepsin (EC 3.4.23.1)-HCl, and with contents of porcine small intestine and caecum were studied. When rapeseed meal was incubated with myrosinase, 5-vinyl oxazolidinethione (OZT) and butenyl and pentenyl isothiocyanates were produced; OZT concentration rose to a plateau after about 2 h. However, when incubated with caecal contents only OZT could be detected; its concentration peaked after about 4-5 h then declined. Under in vitro conditions which attempted to simulate peptic and small intestinal digestion no OZT could be detected; the individual glucosinolates differed in susceptibility to peptic conditions, losses ranging from 3 to 23%. Under the small intestinal conditions the losses of individual glucosinolates ranged from about 7 to 28%. Addition of CuSO4, ascorbic acid, tylosin or a probiotic had little effect on the outcome of peptic or small intestinal incubations but tylosin appeared to slow the degradation of glucosinolates in the presence of caecal contents.

A comparison of effects of body weight and feed intake on digestion in broiler cockerels with effects of tannins.

The effects of body size and feed intake on N digestibility, pancreas and liver weight, and digestive enzyme activities in male broiler chicks were compared with those induced by dietary tannins. Four groups (SSM, ad lib., pair-fed and young) of sixteen birds each (2 weeks old) were used as experimental animals. They were fed on experimental diets for 4 weeks, except the young group which were fed from age 15 d to 24 d only. Two isonitrogenous and isoenergetic diets with (SSM) or without salseed (Shorea robusta) meal (CONTROL) were used. SSM diet was fed ad lib. to SSM group and control diet was fed ad lib. to ad lib. and young birds and to pair-fed birds at same intake level as SSM birds. Birds fed ad lib. utilized their diet more efficiently than the SSM and pair-fed birds. Digestibility of N, both apparent and ileal, was substantially lower with SSM diet than with the control diet. Each of the treatments induced enlargement of the pancreas (g pancreas/kg live weight) when compared with ad lib. birds. There was no difference between the relative liver weights of SSM and ad lib. birds; however, pair-fed and young birds had comparatively bigger livers. In pair-fed birds the trypsinogen activity of pancreatic tissue (U/g pancreatic tissue) was significantly depressed but there was a significant elevation in trypsinogen (U/kg live weight) activity in SSM birds; again pair-fed birds exhibited the lowest value for this variable.(ABSTRACT TRUNCATED AT 250 WORDS)

Activities of enzymes of the pancreas, and the lumen and mucosa of the small intestine in growing broiler cockerels fed on tannin-containing diets.

Diets containing vegetable tannins, predominantly hydrolysable gallotannins, at levels of 13.5, 25 and 50 g/kg were fed to growing broiler cockerels to examine their effect on enzymes in the pancreas, the intestinal lumen and the intestinal mucosa. Pancreas weight per unit live weight showed a significant (P less than 0.05) increase with increasing level of dietary tannin while that of the liver remained unaffected. Trypsin (EC 3.4.21.4) and alpha-amylase (EC 3.2.1.1) activities in the pancreas of birds fed at the highest level of tannins were more than double those from birds fed on a tannin-free control diet. In the intestinal lumen inhibition of trypsin activity increased with increasing level of dietary tannin; alpha-amylase activity was inhibited at intermediate tannin levels but was restored at the highest level. Dipeptidase (EC 3.4.13.11) and sucrose alpha-glucosidase (disaccharidase) (EC 3.2.1.48) in the intestinal mucosa were both inhibited by tannins. Growth of the birds and digestibility of nitrogen were adversely affected by the tannin-containing diets.

Diurnal variations in the concentration, arteriovenous difference, extraction ratio, and uptake of 3-hydroxybutyrate and plasma free fatty acids in the hind limb of lactating sheep.

Four lactating sheep were used to study diurnal variations in the concentration, arteriovenous concentration difference, extraction ratio, and uptake of 3-hydroxybutyrate and plasma free fatty acids by the hind limb of the lactating sheep. The arterial and venous concentrations of 3-hydroxybutyrate showed significant diurnal variations, which appear to be related to the feeding regimen, since values declined after feed withdrawal and rose after refeeding. Throughout the experimental period uptake of 3-hydroxybutyrate by the hind-limb was consistent and none of the small variations in arteriovenous difference, extraction ratio, or uptake of 3-hydroxybutyrate by the hind limb was statistically significant. By contrast, free fatty acid concentrations in arterial blood rose steadily after feed withdrawal. Except at feeding time, there was an output of free fatty acid by the hind limb.

Short-term effects of exogenous growth hormone: effects on milk production and utilization of nutrients in muscle and mammary tissues of lactating ewes.

Exogenous bovine growth hormone at a dose of 0.1 mg kg-1 liveweight increased yields of milk and milk constituents and milk fat content when injected over 5 days into ewes in mid-lactation. These changes in milk production were associated with changes in the supply to, and utilization of, nutrients by leg muscle and mammary tissues. Arterial concentrations of glucose and non-esterified fatty acids increased significantly, concentrations of lactate and 3-hydroxybutyrate tended to increase, and concentrations of triglycerides associated with very low-density lipoproteins decreased significantly. Growth hormone increased mammary uptake of non-esterified fatty acids, decreased mammary uptake of very low-density lipoproteins and tended to reduce the release of lactate from leg muscle. Oxidation of non-esterified fatty acids in the whole body and mammary tissue was increased by growth hormone and there was a tendency for reduction of glucose oxidation in mammary tissues. During injection of growth hormone, blood flow to leg muscle and mammary tissues increased as did the calculated ratio of blood flow; milk yield. These changes in blood flow, together with changes in arterial concentrations and tissue utilizations of key metabolites, were sufficient to account for the synthesis of extra milk and milk constituents.