Untersuchungen zum Futterwert von Strohmehl in der Schweineernährung

[The use of partly-hydrolyzed straw meal in the feeding of weaned piglets. 3. The concentration of several parameters of protein, fat, carbohydrate and mineral metabolism in the blood serum during the use of rations with different portions of partly-hydrolyzed straw meal]

Rations containing varied quotas of partly hydrolysed straw meal (PHS) were provided in mixtures of concentrate and straw meal, and selected parameters of the protein, fat, carbohydrate and mineral metabolism were registered in the blood serum at intervals (2nd and 8th week of keeping) in studies with weaned piglets of the country species. In a parallel experiment the straw hydrolysis product was provided without or after neutralization (with CaCO3) in quotas of 5, 10 and 15% in the mixed feed in comparison to the sole feeding of concentrate. Only some out of the total of 16 parameters ascertained in the blood serum showed reactions of the intermediary metabolism in the test groups caused by feeding. In general, straw crude fibre integration decreased the cholesterol level in the blood serum. Urea concentration in the blood decreased with the growing quota of PHS in the feed mixture. Deviations from the norm of various metabolites, which were mainly reflected in the period near weaning (2nd week of keeping) in an increased concentration of free glycerol and urea in the blood serum, could predominantly be registered after the sole feeding of concentrate. On the whole, there were thus certain interactions with growth performance, which clearly advocate the use of quotas of 10% of the hydrolysed straw product in the feed mixture.

[The significance of fiber for swine nutrition with special reference to HCl-treated straw meal]

The term crude fibre according to the Weend analysis method is insufficient for the nutrition of pigs as it does not comprise pentosanes. During the cooking process they are hydrolysed with diluted acid and do not remain in the crude fibre fraction. As stomach HCl can also hydrolyse pentosane (probably in shorter chains), they are well utilized by the microorganisms in the digestive tract (production of volatile fatty acids). Cereal bran and straw meal contain a particularly high quota of pentosanes in their fibre. The fibre fraction of the plant materials fulfills several functions in the digestive tract: absorption of water at the hydroxyl groups of cellulose and hemicellulose (higher absorption capacity of the digesta and improved passage rate); formation of volatile fatty acids (VFA) by the intestinal bacteria due to the fermentation of pentosanes and cellulose (positive influence of VFA on the mucosa of the intestinal walls); absorption of protein decomposition products (including amines) in the cavities of native plant scaffold substances and absorption of aromatic toxic substances (tyramine, phenol, cresol, tryptamine, indole, skatole, histamine etc.) in the lignin by means of VAN DER WAALS forces and further transport of the toxic substances until they are excreted in faeces. HCl treated straw meal is either a mixture of HCl and straw meal at a ratio of 20 kg half concentrated HCl (17% HCl) and 100 kg straw meal with or without heat treatment (steaming for ca. 30 min). The unsteamed product is called HCl straw meal, the steamed product partly hydrolysed straw meal (PHS). 5-10% HCl--straw meal was successfully used in the rearing of piglets after weaning. In addition to the above-mentioned significance of the scaffold substances for the digestive tract, the HCl improved the pH status in the stomach and the upper region of the small intestine. PHS neutralized with CaCO3 (up to pH 6-7) is suitable for breeding sows, boars, young sows and fattening pigs. PSM contains 25% reducing substances (reducing sugars) in the DM and serves the intestinal bacteria in the production of VFA. In the feeding of breeding sows in the phase of gestation 20-30% of the DM intake could be covered by PSM. The number of viable and rearable piglets was significantly higher than after conventional feeding. HCl--SM and PSM also provide advantages with regard to hygiene. They are not congested by fungi and can well be stored without neutralization.

[The use of a partly-hydrolysed straw meal for the feeding of weaned piglets. 1. Increased production and feed expense as well as nutrient digestibility and buffer capacity in rations with various high portions of partly-hydrolysed straw meal]

In studies with weaned piglets of the land race the usability of partly hydrolysed straw meal (PSM) in concentrate - straw meal mixtures was tested over a period of 56 days (42nd-98th day of life; 1st-8th week of feeding. The hydrolysed straw product was there tested in a parallel experiment each without and after neutralization (by means of CaCO3) in quotas of 5, 10 and 15% as supplement to the concentrate feed (based on dry matter) in comparison to a sole concentrate feeding. Daily weight gain and feed and energy expenditure as well as nutrient digestibility and the buffer effect of the PSM rations were ascertained. Measured by weight gain, feed intake and concentrate- and energy expenditure related weight gain, a 10% quota of partly hydrolysed straw meal in a period near weaning (1st-4th week of feeding) had the highest effect and was far superior to traditional concentrate feeding. Lower quotas of PSM in this period did not show a sufficient dietetic effect (diarrhea symptoms), higher reduced the effect on the performance parameters. In the period more remote from weaning (5th-8th week of feeding) the effect of the straw meal integration was generally reduced, a quota of about 5% proved optimal. The registered higher daily weight gains in the total test period (1st-8th week of feeding in which concentrate - straw meal mixtures (relative 106-130%) were closely related to the daily intake of digestibility organic matter. The decrease in digestibility of organic matter in the total ration remained small with the use of the well fermentable crude fibre from the hydrolysed straw product and the balance was overcompensated by higher feed intake. A pH-value decrease of the feed mixtures and a physiologically suitable influence on the pH-value in the stomachs of the test animals could be ascertained due to the buffer capacity of the hydrolysed straw products used. With regard to this, the non-buffered hydrolysed straw product had a higher effect, which was, among other things, reflected in higher performances.

[The effect of straw meal on the crude protein and amino acid metabolism and digestibility of crude nutrients in broiler hen breeds. 1. Problems, experimental review and N-excretion in the urine]

The metabolization of the straw N and the influence of the straw on N excretion in urine were studied in 2 experiments with colostomized broiler hens and with 15N labelled wheat straw as well as 15N labelled wheat. In experiment 1 the test animals divided up into 4 groups received 0 g, 20 g, 30 g and 40 g straw meal per animal and day in addition to 120 g mixed feed. The daily 15N-excess (15N') intake from the straw was 18.4 mg, 27.5 mg and 36.7 mg. The amount of 15N' daily consumed with the labelled wheat in experiment 2 was 119.7 mg. 40 g straw meal resulted in a significantly increased amount of urine (p less than 0.05). The amounts of urine N and uric acid N were only increased as a tendency. On average the productive N decreased as a consequence of the straw meal supplement from 1070 mg/animal and day (control) to 764 mg/animal and day after 40 g straw meal supplement. The productive 15N' of the labelled wheat was not influenced by the straw meal supplement. The productive 15N' of the straw increased from 3.8 mg/animal and day (20 g straw) to 13.4 mg/animal and day (40 g straw). In contrast to 15N wheat, straw as a 15N source resulted in a lower labelling of uric acid N in comparison with urine N. It can be assumed that the changed metabolization of the straw N is influenced by microbial processes in the intestines.

[Use of partially hydrolyzed and untreated straw meal in the feeding of breeding sows. 3. Nutrient digestibility, feed passage time and mineral balance with the addition of variously treated straw materials compared to concentrate feeding alone]

In studies with 16 breeding sows of the country species the feed value of straw materials and their fitness for use were ascertained in a long-term experiment. On the feeding basis of a concentrate ration (IV) untreated (I), HCl treated (II = HCl treatment without steaming) and partly hydrolysed straw meal (III = HCl treatment with subsequent steaming) were tested. In the course of the experiment and at a nutrient level of 1 (maintenance requirement), the digestibility of the organic matter of the ration and that of some major and trace elements, N and mineral balances as well as feed passage rate and water excretion in faeces were ascertained at selected measuring times. The following mean results were achieved: The integration of all straw materials tested lead to a significant reduction of the digestibility of the organic matter of the total ration, the least negative effect was caused by partly hydrolysed straw meal (III). The fractions crude protein, crude fibre and N-free extracts were mainly affected. Straw meal integration had a gravidity-conditioned influence on the daily N balance. Increased N excretion in faeces could only be compensated by non-pregnant animals by a decreased N excretion in urine. The mineral balance (Ca, P, Na, Cu and Mn) remained largely uninfluenced by the straw supplement. The feed passage rate was reduced by the use of all straw meal variants to ca. 50% of the value measured after the sole feeding of concentrate (IV). Feed passage rate and water excretion in faeces were approximately reciprocal. The digestibility of the organic matter of the straw materials ascertained according to the difference method amounted to 7.4 (I), 18.1 (II) and 27.9% (III); that of the N-free extracts in the same sequence to 10.0, 22.0 and 34.9%. The calculated energetic feed value was for I = 70.7, for II = 154.9 and for III = 240.7 EFUpig/kg DM.

[Effect of a supplement of partly hydrolized straw meal to a diet of fish meal and horse beans on N balance and amino acid excretion in the feces of swine]

2 test pigs each (male castrated pigs) of an average live weight of 51-71 kg received either a wheat/fish meal diet (Ia) or a wheat/horse bean diet (IIa). Due to a supplement of partly hydrolysed straw meal the crude fibre content was increased from 3.0% (= Ia) to 10.1% (= Ib) and from 5.2% (= IIa) to 12.1% (= IIb) in the dry matter. This straw meal supplement decreased the apparent digestibility of the crude protein in I from 92.5 to 85.7% and in II from 89.0 to 79.0%. N-excretion in faeces/100 g DM-intake followed the regression line: y = 228 + 31.2x(r = 0.98) y = mg N/100 g DM-intake x = % crude fibre in the DM of the diet The excretion in faeces/100 g DM-intake of 15 investigated amino acids, too, in each case showed a significant increase with the rising crude fibre content of the diet. The widest growth angle (tan alpha) of all the essential amino acids investigated was shown by lysine and those amino acids with branched chains. The conclusion is that in the presence of a fermentable crude fibre source and a good N-supply those 4 amino acids show a suitable bacterial synthesis rate and a low decomposition rate.