20.500.12556/DKUM-86077 Analiza dejavnikov, ki vplivajo na vsebnost sečnine v mleku krav molznic diplomsko delo Analysis of factors influencing urea content in dairy cow milk Vsebnost sečnine v mleku (MU) je odličen pokazatelj oskrbljenosti krav molznic z beljakovinami. Splošno priporočilo je, da naj mleko krav molznic vsebuje 15‒30 mg MU/100 ml, glede na nekatere raziskave pa naj bi bila vsebnost MU za krave z visoko prirejo mleka 20‒25 mg MU/100 ml. V raziskavi smo želeli raziskati stanje glede vsebnosti MU na območju KGZS Ptuj s poudarkom na kmetiji Hajšek ter proučiti nekatere dejavnike, ki vplivajo na vsebnost MU. V raziskavo smo zajeli skoraj 24.000 kontrol prireje mleka (skupni vzorci) iz ≈ 750 rej za obdobje 2019‒2021, vključno s 34 kontrolami za kmetijo Hajšek. Izkazalo se je, da je vsebnost MU v splošnem prenizka, saj je bilo le 25 % kontrol v optimalnem območju (20‒25 mg MU/100 ml), preko polovice pa pod mejo 20 mg MU/100 ml, od teh pa polovica pod 15 mg MU/100 ml. Vzorci s kmetije Hajšek so bili v 82 % znotraj območja 20‒25 mg MU/100 ml. V raziskavi smo ugotovili značilen vpliv sezone (visoke vrednosti poleti in jeseni, nizke pozimi in spomladi) in leta (celo leto zaniha navzgor ali navzdol) na vsebnost MU. S povečevanjem proizvodnosti in velikosti črede se je povečevala tudi vsebnost MU. Ugotovili smo značilno interakcijo med proizvodnostjo krav in sezono. Visoko proizvodne črede so imele tekom leta višjo in stabilnejšo vsebnost MU. Iz tega razloga na kmetiji Hajšek, ki se po proizvodnosti uvršča v sam vrh, nismo zaznali sezonskega vpliva. Vsebnost MU v nizko produktivnih čredah je bila nižja in bolj variabilna med sezonami. Izven rastne sezone imajo številne črede molznic, zlasti tiste z nizko proizvodnostjo, prenizko vsebnost MU, kar je najverjetneje posledica manj uravnane prehrane krav molznic. Za povečanje vsebnosti MU je priporočljivo izboljšati kakovost osnovne krme (npr. sejano travinje z vključitvijo metuljnic) in ujeti optimalen čas košnje in spravila. In dairy cows, milk urea (MU) is an indicator of feeding management with respect to the by-product of dietary protein breakdown. Optimally, cows have 15-30 mg of urea in 100 ml of milk. According to some studies, MU content should be 20‒25 mg MU/100 ml in highly productive cows. The aim of the study was to explore the situation regarding the MU in the area of KGZS Ptuj with an emphasis on Hajšek farm, and to examine some of the factors affecting MU. The study comprised over 24,000 milk recording data (bulk samples) from ≈750 farms for a period from 2019 to 2021, including 34 recordings for the Hajšek farm. The MU content was found to be generally too low; only 25 % of the MU data reached in the optimal range (20‒25 mg MU/100 ml). Over half of the samples were below the 20 mg MU/100 ml of which a half of samples were below 15 mg/100 ml. About 82 % of samples from Hajšek farm were within the range 20‒25 mg MU/100 ml. In the study, a significant effect of the season (high values in summer and autumn, low in winter and spring) and the year (the entire year fluctuates up or down) on the MU content was found. The increase of the productivity and herd size causes the increase of MU content. We found a significant effect of cow productivity × season. Highly productive herds had higher and more stable MU content during the year. For this reason, there was no seasonal effect found on Hajšek farm, as the farm ranks on the top regarding productivity. In low productive herds, MU content was lower and varied more in different seasons. Outside the growing season, many dairy herds, especially low productivity ones, have too low MU contents. This is indicative of less consistent feeding. To increase MU content, it is recommended to improve the quality of the basic fodder (e.g., sown grasslands with the inclusion of legumes) and to catch the optimal harvesting time. krave molznice sečnina v mleku sezona proizvodnost krmni obrok dairy cows milk urea season productivity ration true true false A. Hajšek Slovenski jezik Angleški jezik Diplomsko delo/naloga 2023-10-04 16:53:59 2023-11-15 08:57:13 2023-11-16 03:06:57 0000-00-00 00:00:00 2023 0 Maribor 0 Maribor 1 spletni vir (1 PDF datoteka (32 str., [2] str. pril.)) 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 637.1:543:547.495.2(043.2)=163.6 172184323 VS_Hajsek_Anze_2023.pdf VS_Hajsek_Anze_2023.pdf 1 947EDA8BDBCC9014ABAF6EFCACD603D8 fad6a5681d09bf9d741823595c24f37f7c0c3dff8ab284c86a3e156f7ad90ba8 30704fde-62d1-11ee-b6aa-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=173303 Fakulteta za kmetijstvo in biosistemske vede 0 0 0