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

[The feeding of differently treated straw materials to piglets after various weaning times. 2. Fatty acids in the large intestine and parameters of protein, fat, carbohydrate and mineral metabolism in the blood serum during the feeding of untreated, HCl-treated and partly-hydrolysed straw meal]

In feeding experiments with piglets of the country species variously treated straw materials were used in concentrate--straw meal mixtures after the traditional weaning date (49th day of life) and studies were made of the fermentation of volatile fatty acids (VFA) in the large intestine (colon) and of the concentration of selected parameters of the protein, fat, carbohydrate and mineral metabolism in the blood serum of the animals. The concentrate--straw mixtures with a 10% straw quota contained untreated (II), HCl treated (HCl treatment without steaming, without (III) and with neutralization, IV) as well as partly hydrolysed straw meal (HCl treatment with subsequent steaming, without (V) and with neutralization with CaCO3, VI) were tested in comparison with sole feeding of concentrate (I) and its combination with wheat bran (VII). With regard to the fermentation processes in the large intestine in a comparison of the feeding groups (I-VII) the highest concentration and production quota of VFA was registered in I and the lowest in II. The straw treatment variants (III, IV, V and VI) took a medium position with regard to this and did not differ from each other. After their application of a significant increase in the molar acetate quota was ascertained in comparison with the sole feeding of concentrate (I), which was also characteristic of the other crude fibre sources (II and VII) and was reflected in the extension of the C2: C3 relation. Only few of the total of 15 selected parameters in the blood serum showed reactions of the intermediary metabolism of the test groups caused by feeding. The decrease of the urea concentration in the serum after the feeding of the treated straw materials (III, IV, V and VI) is particularly remarkable. In general, the urea concentration in the serum was negatively related to growth performance of the test groups. The use of HCl treated straw materials (III-VI) proved to be advantageous in comparison to the sole feeding of concentrate (I) and the use of other crude fibre sources (untreated straw meal (II) and wheat bran, VII) in the feeding regime of the keeping stage 'weaned pigs'.

[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.