Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS
Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS
Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS
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1 st WorkshopXIII International Feed Technology Symposium218CHEMICAL AND PHYSICAL QUALITY OF FORAGES FORDAIRY COWS NUTRITIONBojan Stojanović, Goran Grubić, Nenad Đorđević, Aleksa Božičković, Aleks<strong>and</strong>ra IvetićUniversity <strong>of</strong> Belgrade Faculty <strong>of</strong> Agriculture, Nemanjina 6, 11080 Belgrade, SerbiaABSTRACTForage quality is first determined by content <strong>of</strong> useable energy; crude protein, <strong>and</strong> hisfractions: rumen degradable <strong>and</strong> undegradable protein; fibers: ADF, NDF <strong>and</strong> lignin.Besides the chemical composition, basic parameter that influence on nutritional value<strong>and</strong> quality <strong>of</strong> forages that compose diet is digestibility <strong>of</strong> DM, OM <strong>and</strong> nutrients.Significant part <strong>of</strong> forages in dairy cows diets is necessary for proper ruminal function<strong>and</strong> processes <strong>of</strong> rumen fermentation. The effect <strong>of</strong> forages in dairy cows’ diets depends<strong>of</strong> plant species, stage <strong>of</strong> maturity, method <strong>of</strong> preservation <strong>and</strong> diet composition.Determination <strong>of</strong> forages <strong>and</strong> total mixed rations particle size is significant factor forlactating cows diet formulating. Optimal content <strong>of</strong> physically effective fiber-peNDF indiet <strong>and</strong> proper physical form <strong>of</strong> forages stimulate increasing <strong>of</strong> chewing activity,provide proper ruminal function <strong>and</strong> feed conversion, <strong>and</strong> eliminate appearance <strong>of</strong> milkfat depression <strong>and</strong> metabolic diseases.Key words: forages, quality, cows, nutritionINTRODUCTIONEnergy <strong>and</strong> protein requirements <strong>of</strong> high-yielding lactating cows are difficult to supply,because <strong>of</strong> enormous high-energy requirements <strong>and</strong> in the same time limited capacity fordiet dry matter intake. Considering these facts, formulated ration for lactating cowsshould contain high energy <strong>and</strong> protein concentration in dry matter, <strong>and</strong> should be highdigestible. In practice, these could be providing by using the most quality forages aspossible <strong>and</strong> with high portion <strong>of</strong> concentrate in rations. Quality <strong>of</strong> forages is firstdetermined by content <strong>of</strong> available energy; crude protein, <strong>and</strong> his fractions: rumendegradable <strong>and</strong> undegradable protein; fibers: ADF, NDF <strong>and</strong> lignin. The significantportion <strong>of</strong> forages in lactating cows’ diets is important for proper ruminal function, <strong>and</strong>processes <strong>of</strong> ruminal fermentation. The bottom line for forages portion in cows’ diets is40 % (Grubić <strong>and</strong> Adamović, 2003).The ability <strong>of</strong> formulated optimal diet to supply nutrient requirements <strong>of</strong> high yieldinglactating cows depends <strong>of</strong> his chemical <strong>and</strong> physical characteristics. The particle length<strong>of</strong> forages <strong>and</strong> total mixed ration is important parameter for diet formulation. Rationcontent <strong>of</strong> NDF-fiber (neutral detergent insoluble fiber), has substantially influence onDM intake, proper ruminal function, processes <strong>of</strong> microbial fermentation in rumen,digestibility <strong>of</strong> ration, feed conversion, chemical composition <strong>of</strong> milk (Stojanović <strong>and</strong>Grubić, 2008). Minimal <strong>dietary</strong> fiber content, considers through the concept <strong>of</strong> theirphysically effectiveness. Concept <strong>of</strong> physically effective fiber (peNDF) includes meanparticle length <strong>of</strong> forages <strong>and</strong> total mixed ration, <strong>and</strong> forage <strong>and</strong> <strong>dietary</strong> content <strong>of</strong> NDF,<strong>and</strong> defines their physically effectiveness (Mertens, 1997). Optimal content <strong>of</strong> physically
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