Lucyna Buraczewska

Apparent precaecal digestibility of nutrients and level of endogenous nitrogen in digesta of the small intestine of growing pigs as affected by various digesta viscosities.

Sixteen male growing pigs of about 24kg BW were fitted with both a duodenal re-entrant and a post-valve T-shaped cannula inserted in the caecum. The animals were divided into four groups. Each group received one of the following diets: corn starch-soybean protein isolate-based diet without (diet C) and with carboxymethylcellulose (diet CMC) or a rye-wheat-based diet without (diet RW) and with xylanase addition (diet RWX). The diets provided similar levels of apparent precaecal digestible crude protein (CP), lysine, methionine+cystine, threonine and tryptophan. Additionally, [15N]-yeast was given with the diets during the first 10 days of the experiment. For estimation of digesta viscosity, N-flow of dietary and endogenous origin, apparent precaecal digestibilities of dry matter (DM), CP, amino acids and non starch polysaccharides (NSP) (only in pigs fed diets RW and RWX), ileal and duodenal digesta were quantitatively collected on day 16 and 17, respectively. The endogenous N-proportion was measured by the ratio of 15N enrichment in the digesta and urine. The duodenal and ileal digesta supernatant viscosity increased as carboxymethylcellulose was included into the diet. Xylanase addition to the rye-wheat based diet reduced the viscosity in the ileal digesta. There were no differences in precaecal digestibilities of DM, CP and amino acids between diet C and CMC. The precaecal digestibilities of DM and soluble and insoluble NSP increased from 69.5% to 73.9%, from 1.3% to 47.9% and from 17.0% to 35.4%, respectively, as xylanase was added to the rye-wheat-based diet. The apparent precaecal digestibility of most essential amino acids increased by 2 to 5 percent units. The amounts of endogenous N at the duodenal level were estimated to be 158, 233, 313 and 276mg per 12h per kg0.75 BW of pigs fed diets C, CMC, RW and RWX, respectively. The corresponding values at the ileal level were 95, 107, 164 and 150mg per 12h per kg0.75 BW. For endogenous N amounts, significant differences were observed between diets C and CMC (duodenum) and also between semi-purified and cereal-based diets (duodenum and ileum). Methodological aspects for the estimation of endogenous N using the isotope dilution technique are discussed. Obviously, the digesta viscosity per se does not affect the nutrient absorption and endogenous N flow within the small intestine of pigs. Other properties of complex dietary fibre, digesta passage rate or bacterial activity probably contribute to the observed changes.

Untersuchungen über die Proteinverdaulichkeit und Aminosäurenresorption in verschiedenen Abschnitten des Verdauungstraktes beim Schwein

: The intake, excretion and the rate of flow of protein, methionine and 35S were measured at four pigs (live weight 63 kg) with re-entrant cannulae in the duodenum and the ileocecal region after the oral application of 35S-methionine and the feeding with a wheat + wheat gluten + lysine resp. a protein-free diet over a period of 7 days. From the measured values one pattern each for the N- and the methionine metabolism was laid down with the help of the compartment model, and the endogenous and exogenous levels of protein resp. methionine in the duodenum, the ileum and in feces were estimated.

Response of animals to dietary gramine. I. performance and selected hematological, biochemical and histological parameters in growing chicken, rats and pigs

The effects of feeding varied levels of low‐ and high‐gramine yellow lupin seeds (LG and HG, respectively), and of synthetic gramine added to the diets in amounts ranging from 0.15 to 1.2 g per kg were investigated in one experiment on growing chicken and in two experiments on growing rats. The comparison of LG and HG lupin and the effect of 0.5 g gramine per kg of LG diet were determined in a growth‐balance experiment with pigs. Organ weights and histology, blood parameters and activity of liver enzymes were determined. The response to HG lupin and gramine concentration varied among the species, the rats being more affected than chicken; no adverse effects of HG lupin or gramine were found in growing pigs. The common reaction of rats and chicken to the high levels of gramine (native or synthetic) was the decrease of feed intake and body gain. The increase of the relative weight of liver or kidney, changes in hematological parameters and liver enzymes were found only in rats. The estimated NOAEL (no‐observed‐adverse‐effect level) of gramine was about 0.3g/kg diet for rats, 0.65 g for chicken and at least 0.5 g for growing pigs.

FORMULATION OF PIG DIETS ACCORDING TO ILEAL DIGESTIBLE AMINO ACID CONTENT

Two experiments were conducted to evaluate the relevance of formulating pig diets according to apparent ileal digestible amino acid contents. In Exp. 1, six pigs were fitted with post-valvular T-caecum (PVTC) cannula in order to determine apparent ileal digestibility of crude protein (CP) and amino acids of soyabean meal (SBM), rapeseed meal (RSM), maize (M), wheat (W) and barley (B). In Exp. 2, two consecutive balance trials were performed with four groups of six male pigs (Polish Landrace) of initial body weight of about 28 kg. Pigs were fed according to their metabolic BW with four diets differing in CP levels, formulated on the basis of ileal digestible amino acid content, according to Dutch recommendations (Voedenormen Landbouwhuisdieren, Centraal Veevoederbureau, No. 18, Lelystad, The Netherlands, 1995). Two diets containing low (L-SBM) and high (H-SBM) protein level: 151 and 165 g/kg, respectively, were composed of soyabean meal, maize and barley, and two other diets containing also low (L-RSM) and high (H-RSM) protein level: 161 and 175 g/kg, respectively were composed of rapeseed meal and wheat. In Exp. 1, distinct differences were found between SBM and RSM in their digestibilities of CP (77.0 and 59.5%, respectively) and all amino acids. Among the cereals, CP digestibility and that of most amino acids were the highest for wheat and the lowest for barley. In Exp. 2, urinary N excretion, expressed in percent of intake, was the highest in pigs fed on diets H-RSM (36.2%) and L-RSM (37.0%) and was the lowest on diet L-SBM (30.1%). Accordingly, N retention was lower (P<0.001) after feeding rapeseed than soyabean meal diets (on average 47.5 and 52.2%, respectively). Daily N retention ranged from 20.0 g (L-RSM) to 22.9 g (H-SBM), and these values differed at P<0.05. Possible factors affecting balance differences are discussed.

Ileal digestibility of amino acids in pigs fed barleys differing in protein content

The apparent digestibility of nitrogen and amino acids was measured by the ileal and faecal methods in pigs fed nine barleys differing in nitrogen content (from 1.73 to 2.16 per cent/DM). A positive (r = 0.87) and significant relationship was found between the apparent nitrogen digestibility at the end of the ileum and the crude protein content of barley. Generally, the higher the protein of the grain, the higher the ileal digestibilities of the amino acids. For most amino acids the faecal values were greater than the ileal ones. This being specially so for threonine, tryptophan, histidine and cystine belonging to the nutritionally important amino acid group. When the relationship between the amino acid and nitrogen digestibilities at the level of ileum is considered, the values were found to be similar to that of nitrogen in the case of tryptophan, higher for isoleucine, valine (both 2-3 units), cystine, histidine, leucine, methionine (all 5-6 units) and phenylalanine (10 units) and lower only for lysine and threonine (7-8 dig. units).

The rate of absorption of synthetic lysine and dietary protein in the upper half of the small intestine of pigs.

The aim of the present work was to estimate the rate of lysine absorption in the upper part of the small intestine as related to the absorption of total nitrogen and other amino acids in pigs given feed (barley + sesame meal) supplemented with lysine and fed once or 4 times daily. The experiments were carried out on 6 pigs fitted with reentrant cannulas sited in 3 of them about 4 m and in an other 3 about 9 m distal to the pylorus (mean intestine length was about 18 m). The frequency of feeding influenced the rate of flow of total nitrogen and lysine through the intestine. The content of lysine in the digesta (g/16 g N) during the first 5 hours after morning feeding, and particularly between 8.00-10.00 h, was much higher with once daily than with four times daily feeding while during the subsequent 15 hours the reverse was true. The absorption of lysine occurred at a faster rate than that of the other amino acids and was closest to that of arginine and methionine. On the whole, the net absorption rate of essential amino acids in the upper part of the intestine of pigs was as follows: Lys, Met greater than His, Phe, Leu greater than Trp, Ile, Val greater than Thr (Cys). It seems that the more uniform passage through and absorption from the alimentary tract of synethetic lysine and dietary protein, observed at frequent feeding could contribute to their better utilization for protein synthesis in the organism.

The effects of supplementing a low-protein threonine-deficient diet with different sources of non-essential amino acids on nitrogen retention and gut structure in young pigs

A threonine-adequate control diet and four Thr-deficient (80% of requirement) diets were formulated to contain similar amounts of digestible lysine and the recommended pattern of other standardised ileal digestible essential amino acids (except Thr). Threonine-deficient diets were supplemented with different amounts and sources of non-essential amino acids, namely 0, 20, and 40 g wheat gluten (WG) protein per kg diet or 17.6 g monosodium glutamate (MSG) per kg diet. Each diet was fed for 28 days to six piglets (initial BW 15 kg). Supplementation of the Thr-deficient diet with WG or MSG had a positive effect on N retention (5.9–8.5%) in younger, but not in older, pigs. Furthermore, it reduced the plasma Thr level and increased threonine dehydrogenase activity in the liver and pancreas. The treatment effects on intestinal morphology differed according to the histological criteria used. It may be concluded that non-essential amino acids added to the low-protein diet deficient in Thr seem to improve utilisation of these amino acids for protein deposition in very young pigs, whereas their effects on the structure of the small intestine are equivocal.

The effect of pelleting feed supplemented with lysine on its utilization by young pigs.

The aim of the experiment was to study the effect of pelleted and meal-form of a diet supplemented with lysine on passage rate through the digestive tract (DT) and utilization by young pigs. The experiment was carried out on 20 young boars of about 10 kg live weight, divided into 3 groups. The experimental diet composed of feeds of plant origin (barley 80.0%, sesame meal 10.6%, soybean meal 7.0%; total crude protein 15.3%) and supplemented with L-lysine to total level of 0.8% was fed twice daily as: a) a meal mixed with water (group I), b) dry meal (group II), c) pellets (group III). The experiment lasted 51 days including the last 6 days for nitrogen balance. On the first day of the collection period 3% Cr2O3 was included in the first meal to estimate the passage rate of feed. The average body weight at the end of the experiment was similar in group I and II (29.7 and 28.5 kg) but significantly lower as compared to group III (31.7 kg). Differences between the groups in the growth rate were higher during the first than the last period of the experiment. Pelleting reduced feed consumption per kg gain by about 12%. It was calculated that the increase in the live weight in group III could be attributed to the deposit of both protein and fat in the body. Large individual differences were observed in the rate of passage through DT and this probably effected the lack of significant differences between the groups.