<p>Pravilna ishrana preživara je važna za održanje zdravstvenog stanja životinja, a takođe je i ključna za efikasnu i ekonomičnu proizvodnju mleka i mesa. Kod visokoproizvodnih preživara, kao što su tovna junad i mlečne krave, energetske potrebe su velike kako bi se ostvario brz prirast telesne mase i visok prinos mleka. Termički tretmani se koriste za poboljšanje hranljivih, higijenskih, fizičkih i hemijskih karakteristika hrane za životinje. Osnovni cilj istraživanja u okviru ove disertacije je analiza uticaja različitih termičkih tretmana na promene skrobne komponente i svarljivost kukuruza kod preživara. U tu svrhu primenjeni su tretmani peletiranja, parnog flekičenja, mikronizacije i ekstrudiranja na uzorcima kukuruza i potpune smeše za krave muzare. Promene u strukturi skrobnih granula su praćene pomoću skening elektronske mikroskopije i diferencijalne skenirajuće kalorimetrije, dok su promene u hidrataciji i bubrenju uzoraka određene analizom kriva pastiranja, indeksa apsorpcije vode (WAI) i indeksa rastvorljivosti u vodi (WSI). In situ tehnikom je praćena promena brzine svarljivosti skroba i suve materije u buragu preživara i uticaj različitih termičkih tretmana na mesto varenja skroba kukuruza. Promene u svarljivosti organske materije (SOM) kroz ceo digestivni trakt preživara su određene in vitro multi-enzimskom metodom.<br />Na osnovu rezultata DSC analize uzoraka kukuruza i smeša utvrđeno je da su parno flekičenje, mikronizacija i peletiranje blagi tretmani, dok je ekstrudiranje oštriji tretman koji dovodi do potpunije želatinizacije skroba. U uzorku parno flekičanog kukuruza došlo je do interakcije degradiranih komponenti (skroba, proteina i lipida) na molekularnom nivou i nastanak jedinjenja sa većom molekulskom masom i smanjenom rastvorljivošću. U dva uzorka ekstrudiranog kukuruza zbog većih sila smicanja i dužeg vremena zadržavanja materijala u ekstruderu došlo je do delimične želatinizacije koja je bila praćena dekstrinizacijom skroba. In situ metodom su za uzorak netretirane smeše određene najniže vrednosti nestajanja SM i skroba u buragu, dok su svi primenjeni termički tretmani doveli do značajnog povećanja razgradnje SM i skroba. Najmanje povećanje razgradnje skroba u poređenju sa netretiranom smešom je zabeleženo kod smeše koja je sadržala parno flekičan kukuruz, dok je u svim uzorcima ekstrudiranih smeša došlo do razgradnje velike količine skroba već tokom prva 3h inkubacije. U poređenju sa netretiranom smešom, svi primenjeni termički tretmani su doveli do povećanja brzine razgradnje skroba u manjoj ili većoj meri a u zavisnosti od vrste i intenziteta tretmana. Značajne razlike u karakteristikama razgradnje skroba su zabeležene nakon variranja procesnih parametara ekstrudiranja, dok su uočene razlike između smeša koje su sadržale mikronizirani kukuruz bile mnogo manje izražene. Mobile bag metodom određena je svarljivost skroba u crevima koja je u netretiranoj i svim termički tretiranih smešama iznosila 100%. Statističkom obradom rezultata nije utvrđeno značajno povećanje SOM kukuruza i smeše nakon primenjenih termičkih tretmana u poređenju sa netretiranim uzorcima.</p> / <p>Proper ruminant nutrition is important for maintaining the health of animals, and it is also crucial for the efficient and economical production of milk and meat. In high-yielding ruminants, such as fattening cattle and dairy cows, energy needs are high in order to achieve rapid weight gain and high milk yield. Thermal treatments are used to improve nutritional, hygienic, physical and chemical characteristics of animal feed. The main objective of this research is the analysis of the influence of various thermal treatments on changes in the starch component and the digestibility of corn in ruminants. For this purpose pelleting, steam flashing, micronization and extrusion of maize samples and complete mixture for dairy cows were applied. Changes in the structure of starch granules were monitored by scanning electron microscopy and differential scanning calorimetry (DSC), while changes in the hydration and swelling of samples were determined by analyzing pasting properties, water absorption index (WAI) and water solubility index (WSI) of samples. In situ technique was used to determine the changes in the rate of digestibility of starch and dry matter in rumen and the influence of various thermal treatments on the site of digestion of corn starch. Changes in the organic matter digestibility (OMD) through the entire digestive tract of the ruminants are determined by the in vitro multi-enzymatic method.<br />Based on the results of DSC analysis of corn and complete feed samples, it has been found that steam flaking, micronization and pelleting are mild treatments, while the extrusion is more severe treatment that leads to a more complete starch gelatinization. In steam flaked corn interaction of degraded components (starch, proteins and lipids) at the molecular level resulted in the formation of compounds with higher molecular weight and reduced solubility. In two samples of extruded corn, due to the higher shear rate and longer retention time of the material in the extruder, there was partial gelatinization followed by dextrinisation of starch. In untreated complete feed, the lowest values of DM and starch disappearance in rumen were determined using in situ method, while all the applied thermal treatments led to a significant increase in the degradation of DM and starch. The smallest increase in degradation of starch in comparison to untreated mixture was observed in a mixture containing steam flaked corn, while in all extruded mixtures large amount of starch was degraded during the first 3 hours of incubation. Compared to the untreated mixture, all applied thermal treatments resulted in an increase in the degradation rate of starch to a lesser or greater extent depending on the type and intensity of the treatment. Significant differences in the degradation characteristics of the starch were observed after variation of the extrusion processing parameters, while the observed differences between the mixtures containing micronized corn were much less pronounced. Digestibility of starch in the intestine was determined with mobile bag method, which was 100% in untreated and all thermally treated mixtures. Statistical analysis of the results did not show a significant increase in OMD of maize and mixtures after the applied thermal treatments compared to the untreated samples.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)104902 |
| Date | 19 September 2017 |
| Creators | Kokić Bojana |
| Contributors | Dokić Ljubica, Lević Jovanka, Fišteš Aleksandar, Šoronja-Simović Dragana, Kučević Denis |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | Unknown |
| Type | PhD thesis |
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