Silvopastures integrate trees, forages, and livestock. Tall fescue, the dominant forage in much of the U.S., harbors an endophyte that produces toxic ergot alkaloids. Diluting the sward with other forages can reduce ergot alkaloid concentrations, but it is unknown how shade impacts alkaloid production and productivity of different forage mixtures. This study tested the effects of increasing shade and mixture complexity on sward yield, botanical composition, nutritive characteristics and ergot alkaloid concentrations. Slatted shade structures created 30, 50, and 70% shade compared to full sun. Three forage mixtures were evaluated (SIMPLE = tall fescue and white clover; INTERMEDIATE = SIMPLE + orchardgrass and red clover; and COMPLEX = INTERMEDIATE + Kentucky bluegrass, birdsfoot trefoil, and alfalfa). Fifty and 70% shade reduced yield while red clover and orchardgrass dominated shaded swards. Birdsfoot trefoil, Kentucky bluegrass, and white clover did not perform well in any treatment. Nutritive value declined beneath shade in spring and fall. Sward ergot alkaloid concentration increased beneath shade in simple mixtures because of greater proportions of tall fescue. In the intermediate and complex mixtures, ergot alkaloids were diluted by other forage species and was not affected by shade. This illustrates the importance of incorporating multiple species into the sward. Low light levels may not have been sufficient to meet the forages' high energetic demands in the spring. Even though total forage production or nutritive value may be sacrificed during part of the year, this may be compensated for by diverse swards diluting ergot alkaloid concentrations. / Master of Science

<p>U okviru doktorske disertacije ispitana je mogućnost proizvodnje<br />fermentisanog mlečnog napitka uz primenu različitih vrsta i koncentracija<br />nekonvencionalnog startera čajne gljive: a) nativnog inokuluma-I<br />(10% i 15%) b) koncentrovanog mikrofiltracijom - MFI (10% i 15%) i c)<br />koncentrovanog uparavanjem - UPI (1,5%, 3,0%, 10% i 15%). Varijante<br />fermentisanog mlečnog napitka dobijene su kori&scaron;ćenjem mleka sa 0,9%<br />i 2,2% mlečne masti. Za pobolj&scaron;anje fizičko-hemijskih i teksturalnih<br />karakteristika proizvoda u mleko pre inokulacije dodato je 0,02% enzima<br />transglutaminaze (aktiviran na 40&deg;C, a posle 2 sata je inaktiviran na<br />80&deg;C, 1 minut). Fermentacija mleka (pri temperaturi 42&deg;C) uz kori&scaron;ćenje<br />inokuluma čajne gljive praćena je do postizanja pH vrednosti 4,5.<br />Nakon proizvodnje analizirana je nutritivna vrednost fermentisanih<br />mlečnih napitaka: sadržaj masti, proteina, laktoze, galaktoze, glukoze,<br />fruktoze, mlečne i sirćetne kiseline, etanola, vitamina (B1, B2, B6 i<br />C), minerala (Ca, Mg, K, Na, Pb, Cd, Cu, Zn) i masnih kiselina. Sadržaj<br />odabranih komponenata u napicima praćen je tokom 10 dana skladi&scaron;tenja.<br />Fizičko-hemijske osobine (kiselost, sinerezis i sposobnost vezivanja<br />vode), teksturalne karakteristike (čvrstoća, konzistencija, kohezivnost i<br />indeks viskoziteta) i viskozitet uzoraka praćeni su nakon proizvodnje i<br />posle 10 dana skladi&scaron;tenja. Ukupan broj bakterija sirćetne kiseline (BSK)<br />i kvasaca u fermentisanim napicima analiziran je nakon proizvodnje i<br />tokom skladi&scaron;tenja. Varijante fermentisanih mlečnih napitaka senzorno<br />su ocenjene nakon proizvodnje.<br />Na osnovu rezultata ispitivanja utvrđeno je da fermentacija mleka<br />uz primenu nekonvencionalnog startera čajne gljive predstavlja složen<br />biohemijski proces pri čemu fermentacija traje od 9 do 12 sati i prosečno<br />je dva puta duža od fermentacije mleka u proizvodnji probiotskog i<br />tradicionalnog jogurta. Sadržaj laktoze tokom fermentacije mleka manji<br />je prosečno za 19,6% u odnosu na sadržaj laktoze u mleku. Uzorci<br />proizvedeni sa nativnim inokulumom uz primenu transglutaminaze i<br />koncentrata proteina surutke imaju za 15% niži sadržaj laktoze, a uzorak<br />15% I za 2% niži sadržaj u odnosu na uzorak 10% I. Uzorci proizvedeni<br />sa 10% MFI i 15% MFI imaju za 11%, odnosno 21% niži sadržaj laktoze<br />nakon proizvodnje u poređenju sa odgovarajućim uzorcima proizvedenim<br />uz primenu nativnog inokuluma. Sniženje sadržaja laktoze je<br />praćeno povećanjem sadržaja galaktoze i L-mlečne kiseline u svim uzorcima.<br />D-mlečna kiselina, sirćetna kiselina i etanol zastupljeni su u veoma<br />malim koncentracijama.<br />Imajući u vidu značaj vitamina C u ishrani i količinu detektovanu<br />u fermentisanom mlečnom napitku, konzumiranjem 500 g napitka<br />dobijenog primenom čajne gljive mogu da se zadovolje dnevne potrebe<br />za vitaminom C.<br />Tokom proizvodnje fermentisanih napitaka sadržaj vitamina B1<br />poraste za 5,09%, vitamina B2 za 2,65% i B6 za 2,03% u odnosu na<br />mleko. U fermentisanom mlečnom napitku iz mleka sa 2,2% masti<br />sadržaj vitamina B6 je povećan 24,76% u odnosu na sadržaj u polaznom<br />mleku. Fermentisani mlečni napici proizvedeni primenom čajne<br />gljive iz mleka sa 0,9% i 2,2% masti sa dodatkom 10% inokuluma<br />čajne gljive sadrže najvi&scaron;e vitamina B2 koji iznosi 108 (&mu;g/100g), odnosno<br />136 (&mu;g/100g). Mikrobiolo&scaron;ki sastav napitaka se razlikuje u zavisnosti<br />od vrste i sastava kori&scaron;ćenog inokuluma. Najveći broj BSK<br />(4,5 &middot; 104ćelija/mL) i kvasaca (9 &middot; 104 ćelija/mL) je u uzorku 10% MFI,<br />dok je manji u napitku 10% I (BSK: kvasci= 4,05 &middot; 104: 4,5 &middot; 104).<br />Dodatkom transglutaminaze u minimalnoj koncentraciji od<br />0,02% postižu se znatno bolje fizičko-hemijske i reolo&scaron;ke karakteristike<br />fermentisanih mlečnih napitaka dobijenih iz mleka sa 0,9% masti.<br />Generalno posmatrano, kori&scaron;ćenjem 10% nativnog inokuluma za<br />proizvodnju napitaka iz mleka sa 0,9% i 2,2% masti dobijaju se proizvodi<br />optimalnih hemijskih, mikrobiolo&scaron;kih i senzornih karakteristika.<br />Funkcionalni fermentisani mlečni napici proizvedeni uz primenu različitih<br />vrsta i koncentracija čajne gljive su proizvodi visoke nutritivne<br />vrednosti namenjeni različitim kategorijama potro&scaron;ača.</p> / <p> The possibility of fermented milk beverages manufacture<br /> by applying non-convenctional starter culture - tea fungus<br /> inoculum: a) natural inoculum (10% and 15%); b) concentrated<br /> by microfiltration (10% i 15%); c) concentrated by evaporation<br /> (1.5% and 3.0%) have been investigated. All fermented milk samples<br /> were produced from milk of 0.9% and 2.2 % fat content.<br /> Improvement of rheological properties of low fat fermented milk<br /> products by addition of enzyme transglutaminase (TG) was<br /> achieved. Transglutaminase (Activa MP, Ajinomoto Co. Inc.,<br /> Hamburg, Germany) was activated in milk at 40&deg;C for 2 hours,<br /> then it was inactivated by high temperature (80&deg;C for 1 minute)<br /> prior to fermentation. After cooling to optimal temperature<br /> (42&deg;C), chosen starter culture was added in milk. In all cases<br /> fermentation stopped when the pH=4.5 was reached.<br /> Nutritive characteristics of samples: content of proteins,<br /> lactose, galactose, glucose, fructose, lactic and acetic acid, ethanol,<br /> vitamins (B1, B2, B6 and C), minerals (Ca, Mg, K, Na, Pb,<br /> Cd, Cu, Zn) and total fatty acids content were analysed after<br /> production. Selected components were determined after 10 days<br /> of storage. Physico-chemical characteristics (acidity, syneresis,<br /> water-holding capacity), textural characteristics (firmness,<br /> consistency, cohessivnes, and index of viscosity) and viscosity<br /> were measured at 5&deg;C after production and during 10 days of<br /> storage.<br /> On the basis of the obtained results it can be concluded<br /> that milk fermentation lasted from 9 to 12 hours and is two times<br /> longer compared to fermentation during probiotic and traditional<br /> yoghurt production. Lactose content decreased during fermentation<br /> for 19.6% compared to milk. Higher transformation of lactose<br /> was determined in samples produced by using microfiltration<br /> inoculum. Decreasing of lactose content affected the increased<br /> galactose and L-lactic acid content. Content of D-lactic acid,<br /> acetic acid and ethanol were detected in low concentrations. High<br /> concentration of ascorbic acid in beverage contributed that 500 g<br /> fermented milk beverage could fullfill recommended daily intake<br /> for vitamin C. Sample produced from milk of 2.2% fat content<br /> using 10% natural inoculum contained the highest concentration<br /> of vitamin B2 &ndash; 136 (&mu;g/100g).<br /> The highest total cell count of acetic acid bacteria was<br /> 4.5 &middot; 104 cfu/ml and yeasts 9 &middot; 104 cfu/ml in samples produced by<br /> using 10% microfiltrated inoculum. Sample produced from milk<br /> of 0.9% fat content by applying 10% natural inoculum had also<br /> high number of acetic acid bacteria and yeasts in ratio 4.05 &middot; 104 :<br /> 4.5 &middot; 104.<br /> The sample having tea fungus concentrated inoculum<br /> and transglutaminase had the best textural characteristics. Fermented<br /> dairy beverages produced by 0.02% TG application had<br /> much better textural characteristics than those without TG.<br /> Generaly, fermented dairy drinks produced from milk of<br /> 0.9 and 2.2% fat content with addition of natural inoculum in<br /> concentration of 10% showed optimal sensory, nutritive and rheological<br /> characteristics.<br /> Therefore, fermented dairy drinks produced with tea<br /> fungus inoculum could be classified as high valuable functional<br /> food intended for all consumer categories.</p>