The effects of polysaccharides and tannins present in the hulls of field beans (Viciu fubu L.) on the digestion of amino acids, starch and lipid were studied in poultry. A control diet without hulls and the same diet substituted with 400 g hulls/kg diet from three different varieties of beans were fed to 3-weekold chicks for 4 d. Digestibility coefficients for amino acids, starch and lipid were calculated from measurements made of these nutrients in the diets and the freeze-dried excreta with the aid of titanium dioxide as a marker. Activities of trypsin (EC 3.4.21.4), u-amylase (EC 3.2.1. l), and lipase (EC 3.1.1.3) in digesta removed from the upper jejunum, sucrase (EC 3.2.1.48) in the gut mucosa from the upper jejunum, and u-amylase and lipase in the pancreas were measured. The hulls were analysed for their polysaccharide and tannin contents. Results showed that the hulls were mostly carbohydrate in composition, with cellulose the predominant polysaccharide. Tannins present in the hulls of two colouredflowering varieties (Brunette and Minica) were of the condensed type. The diet with tannin-free hulls (white-flowering variety Medes) lowered slightly the digestion of amino acids, starch and lipid compared with the control diet. This effect was believed to be due to inhibition of digestive enzymes, possibly through their adsorption onto the hulls. Diets with tannin-rich hulls (varieties Brunette and Minica) caused a large reduction in the digestion of amino acids, starch and lipid compared with the control diet mainly due to inactivation of digestive enzymes by the formation of tannin-enzyme complexes in the digestive tract. Enzyme activities could be partially restored by the addition of polyvinylpyrrolidone to the digesta. Tannins inactivated trypsin the most, u-amylase to a lesser extent and lipase the least and as a consequence lowered the digestion of amino acids the most, starch to a lesser extent and lipid the least. Tannins did not induce an increased pancreatic production of digestive enzymes, nor did they affect activity of jejunum mucosal sucrase. Condensed tannins from Brunette and Minica hulls were partially extractable in methanol alone, but required acidic methanol for fuller extraction. The vanillin: anthocyanidin ratio suggested that tannins were polymerized to the same degree in the Brunette and Minica varieties, both in the methanol and acidic methanol extracts. Hulls from the variety Minica contained a greater amount of methanol-extractable tannins, the quantity of remaining tannins that required acidic methanol for extraction being the same for both varieties.Nutrient availability: Dietary fibre: Tannins: Viciu fubu L.: Chick Non-starch polysaccharides and condensed tannins have been shown to interfere with nutrient digestion in the single-stomached animal and to promote the excretion of endogenous nitrogen. The role of condensed tannins as enzyme inhibitors through the formation of tannin-enzyme complexes is well documented from the numerous in vitro studies undertaken. Yet there is still ...

An experiment was designed to assess the effects of graded levels of beta-mannanase on performance and body weight uniformity of male broilers provided with diets based on corn and soybean meal and devoid of antibiotic growth promoters or coccidiostats. Four dietary treatments contained 0, 50, 80, and 110 MU of Hemicell/ ton (where 1 MU = 10(6) enzyme activity units, 100 MU/ton is manufacturer's recommendation). Each treatment contained 15 pens with 40 birds/pen. Individual bird weights were determined on d 0, 21, and 42. From 21 to 42 d of age, feed intake for the 80 MU/ton treatment was significantly greater than the 50 MU/ton treatment. beta-Mannanase inclusion at 80 or 110 MU/ton induced improvements (P < 0.05) in weight gain (3.9 to 4.8%) and feed efficiency (3.5 to 3.8%) over the control, whereas inclusion of 50 MU/ton resulted in no significant benefit. There were no significant differences between 80 or 110 MU/ton. The experiment demonstrated that dietary inclusion of beta-mannanase at approximately 50 MU/ton is not sufficient for maximum response. Inclusion at 80 MU/ ton improved broiler gains and feed conversion and increasing to 110 MU/ton resulted in no significant additional response.

1. To improve the accuracy with which true metabolisable energy (TME) values of feedingstuffs are determined, a modification to the assay based on tube-feeding is proposed. 2. To ensure that the gastrointestinal tracts of the experimental birds are as empty as possible at the start of the assay it is recommended that the normal food is withdrawn 48 h before tube-feeding. 3. In order to partly alleviate the effects of starvation, all birds are given two doses of 25 g glucose (as an aqueous solution) about 40 and 16 h before tube-feeding. Birds, from which endogenous energy losses are to be derived, are fed 50 g glucose rather than given no food. 4. All birds are given 50 ml water by tube about 32 h after feeding to overcome any effects induced by low water intake. 5. A comparison of the two procedures with 8 feedingstuffs showed that the mean coefficient of variation was reduced from 5.5% to 1.5% for TME and from 4.7% to 1.8% for TME.

The digestion of starch and fibre by adult cockerels fed peas which were whole, ground, autoclaved, heated, dehulled, cooked or supplemented with a cellulose degrading enzyme was studied. The starch in ground peas that had been autoclaved, heated or dehulled was slightly, though not significantly, better digested than the starch in peas that had been ground only. Feeding peas whole greatly reduced starch digestibility. Cooking failed to improve starch digestibility as retrograded starch produced in the cooking process was not digested. The more finely ground the foodstuff, the better the in vitro enzymatic hydrolysis of starch. Starch digestibility correlated well (r2 = 0.80) with the true metabolisable energy values obtained for the different pea treatments. In experiment 1 cockerels digested on average 0.22 of the pea fibre from the different forms of peas. A significant decrease in xylose digestion was observed when birds were fed dehulled peas, birds excreting more xylose than they ingested. In experiment 2, cockerels digested on average 0.38 of the pea fibre from different forms of peas. A reduction in fibre digestion was observed when birds were fed cooked peas as a consequence of a decreased digestibility of all monosaccharide residues. A slight increase in fibre digestion was observed when peas were augmented with 'cellulase', entirely because of an increase in xylose digestion.

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