Untersuchungen zum Einsatz von teilhydrolysiertem und unbehandeltem Strohmehl in der Fütterung von Zuchtsauen

[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 partly-hydrolyzed and untreated straw meal in the feeding of breeding sows. 5. Concentration, production and absorption of volatile fatty acids in the large intestine]

In 2 experiments with a total of 28 breeding sows of the country species studies were made of the fermentation, production and absorption of volatile fatty acids (VFA) in the large intestine after feeding variously treated straw materials in concentrate--straw meal mixtures. Experiment 1 ascertained that supplements of untreated (I), HCl treated (II) and partly hydrolysed straw meal (III, treatment with subsequent steaming) caused a decrease of the VFA concentration as well as considerable molar changes of the VFA in the caecal and colonal digesta in comparison of the sole feeding with concentrate (IV). The straw fibre integration increased the molar acetate quota at the expense decreased propionate and butyrate fermentation. Considering the straw meal variants this effects was least distinct after the feeding of partly hydrolysed straw meal (III). In experiment 2, which comprised the simultaneous ascertainment of VFA production in the feeding variants I and III and which was based on a representative number of animals per test group (n = 10), there were significant differences between the production quotas (I = 992; III = 1,300 mmol/animal.d) and in the absorption quotas of VFA (I = 63; II = 78%). The digestible energy from the VFA in the large intestine amounted to 711 kJ/d (I) and 1,183 kJ/d (III). The derived higher net energy gain from the hydrolysed straw product (III) was calculated at 590 kJ (40EFUpig/kg DM) and discussed together with results of feed value increase from the digestibility experiments.

[Use of partly hydrolyzed and untreated straw meal in the feeding of breeding sows. 4. Influence on embryonic mortality and fertility]

The influence of a supplement of variously treated straw materials to a ration to dry concentrate (= 1), (untreated = 2, steamed = 3, HCl-treated = 4 and partly hydrolysed = 5) during gestation on fertility and rearing performance, the embryonic survival quota of fertilized ova as well as on some selected metabolites in the blood serum was studied in 3 experiments. The integration of untreated straw meal resulted in significantly diminished performances in comparison to test groups 1 and 5 in all tested parameters of fertility and rearing performance (weight of litter). The best results were achieved in all experiments with rations of concentrate and partly hydrolysed straw meal. The individual test groups the following performance values (number of piglets born alive, weight of litter in kg) were achieved: 1 = 9.3, 12.3; 2 = 6.5, 8.2; 3 = 7.5, 9.6; 4 = 8.6, 12,4; 5 = 10.6, 14.4). Ration specific reactions could only be proved for the parameters glucose and urea out of the metabolites (insulin, glucose, cholesterol, urea tri-iodine thyronine and thyroxine).

[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.