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1.
PRIMERJALNA ANALIZA KAKOVOSTI MLEKA NA IZBRANIH KMETIJAH KOROŠKE REGIJE Z RAZLIČNIMI MOŽNOSTMI ZA KMETOVANJE
Simona Gologranc, 2015, magistrsko delo/naloga

Opis: V nalogi smo preučevali tehnološko kakovost mleka glede na različne možnosti za kmetovanje (območja z omejenimi dejavniki (OMD) in nižinska območja, ki ne sodijo v OMD). V raziskavo smo vključili 18 kmetij iz koroške regije: 6 iz gričevnato hribovskega, 7 iz gorsko višinskega in 5 iz nižinskega območja. Z anketo smo pridobili informacije o staležu živali, načinu reje in molže, krmnem obroku ipd. Kakovost mleka (sestava, zmrziščna točka in skupno število mikroorganizmov ter somatskih celic) smo določili s pomočjo podatkov AT kontrole (mesečne kontrole), standardnih laktacij ter analiz bazenskih vzorcev Mlekarne Celeia. Rezultati analiz mleka niso pokazali bistvenih razlik v sestavi in kakovosti mleka med preučevanimi območji. Z anketo smo ugotovili, da razvrstitev kmetij v preučevana območja ni nujno povezana z drugačnim načinom kmetovanja in prehranske oskrbe krav. Raziskava je nadalje pokazala, da rezultati AT kontrole niso neposredno primerljivi z analizami bazenskih vzorcev. Potrebno je ločiti med kakovostjo oddanega in prirejenega mleka. Do največjih razlik med obema analizama prihaja v vsebnosti somatskih celic (SC), saj kmetje mleka krav, ki imajo ob kontroli povečano število SC, najverjetneje ne oddajo v mlekarno. Informacije AT kontrole omogočajo rejcu prilagajanje rejskega dela, nadzor zdravstvenega stanja in izločanje manj kakovostnega mleka, zaradi česar dobi mlekarna mleko boljše kakovosti.
Ključne besede: mleko / tehnološka kakovost / območja z omejenimi dejavniki / OMD
Objavljeno: 25.08.2015; Ogledov: 589; Prenosov: 67
.pdf Polno besedilo (1,31 MB)

2.
Spremljanje stanja in predlog ukrepov za zmanjšanje pogostosti mastitisov pri molznicah v slovenskih čredah
Damjana Flere, 2016, magistrsko delo/naloga

Opis: Število somatskih celic (ŠSC) je pokazatelj zdravstvenega stanja mlečne žleze, ki vpliva tudi na tehnološko kakovost mleka. Cilj magistrskega dela je bil preučiti stanje na področju ŠSC v Sloveniji in analizirati dejavnike, ki vplivajo nanj (pasma, zaporedna laktacija, stadij laktacije, leto in sezona telitve, proizvodnost in velikost črede, proizvodnost živali). Analizo smo naredili na zbranih podatkih AT4 kontrole mlečnosti za obdobje 5,5 let za celotno Slovenijo (n3,2×106 kontrol). Na podvzorcu 10 % naključno izbranih čred (n220.000 kontrol) smo statistično ovrednotili pomembnejše vplive na ŠSC. Ugotovili smo, da imajo med preučevanimi dejavniki največji vpliv nivo proizvodnosti živali, zaporedna laktacija in pasma. V splošnem velja, da je večja mlečnost (dnevna ali v standardni laktaciji) povezana z nižjim ŠSC. Največje ŠSC je bilo pri črno beli pasmi, sledili sta ji rjava in lisasta pasma ter nazadnje križanke med lisasto in pasmami, usmerjenih v prirejo mleka. Vpliv zaporedne laktacije na ŠSC je bil izrazit, ostali preučevani dejavniki (proizvodnost črede, leto in sezona telitve) pa so pokazali manjši ali zanemarljiv vpliv na ŠSC. V okviru magistrskega dela smo pregledali sisteme nadzora ter ukrepe za zmanjšanje pojavnosti mastitisov v različnih državah v Evropi in po svetu. Na osnovi pregleda literature in dobljenih rezultatov smo sestavili priporočila za zmanjšanje pojavnost mastitisov v slovenskih čredah krav molznic.
Ključne besede: somatske celice, mastitis, programi nadzora nad mastitisi
Objavljeno: 01.06.2016; Ogledov: 424; Prenosov: 27
.pdf Polno besedilo (1010,82 KB)

3.
Prediction of standard lactation curves for primiparous Holstein cows by using corrected regression models
Janez Jeretina, Drago Babnik, Dejan Škorjanc, 2015, izvirni znanstveni članek

Opis: Prediction of the expected milk yield is important for the management of the primiparous cows (PPC) with a few or no data on their own milk productivity. We developed a system of regression equations for predicting milk yields in standard lactation. The models include the systematic effects of the calving season, the five-year rolling herd average of milk yield of PPC, the breeding values of the parents for milk production, and daily milk recordings. A total of 21,901 lactations of Holstein PPC were collected during the regular monthly milk recordings of cows in the Republic of Slovenia. By including daily milk recordings in the model, the coefficients of determination of regression models for the prediction of milk yield increase: without known recordings (M0) R 2 =0.80; with one recording (M1) R 2 =0.82; with two first consecutive recordings (M2) R 2 =0.86; and with three recordings (M3) R 2 =0.89. Deviations of milk yield up to 500 kg in a standard lactation (<1.6 kg/day) were as follows: with the model M0, they occurred in 53.4% of PPC; with M1, they occurred in 56.3% of PPC; with M2, they occurred in 64.5% of PPC; and with M3, they occurred in 70.9% of PPC. We concluded that the developed system of regression models is an appropriate method for milk yield prediction of PPC.
Ključne besede: primiparous cows, milk yield, prediction, lactation curves, regression equations
Objavljeno: 24.07.2017; Ogledov: 67; Prenosov: 1
.pdf Polno besedilo (497,85 KB)

4.
A new somatic cell count index to more accurately predict milk yield losses
Janez Jeretina, Dejan Škorjanc, Drago Babnik, 2017, izvirni znanstveni članek

Opis: Intramammary infection and clinical mastitis in dairy cows leads to considerable economic losses for farmers. The somatic cell concentration in cow's milk has been shown to be an excellent indicator for the prevalence of subclinical mastitis. In this study, a new somatic cell count index (SCCI) was proposed for the accurate prediction of milk yield losses caused by elevated somatic cell count (SCC). In all, 97238 lactations (55207 Holstein cows) from 2328 herds were recorded between 2010 and 2014 under different scenarios (high and low levels of SCC, four lactation stages, different milk yield intensities, and parities (1, 2, and _>3). The standard shape of the curve for SCC was determined using completed standard lactations of healthy cows. The SCCI was defined as the sum of the differences between the measured interpolated values of the natural logarithm of SCC (ln(SCC)) and the values for the standard shape of the curve for SCC for a particular period, divided by the total area enclosed by the standard curve and upper limit of ln(SCC)=10 for SCC. The phenotypic potential of milk yield (305-day milk yield - MY305) was calculated using regression coefficients estimated from the linear regression model for parity and breeding values of cows for milk yield. The extent of daily milk yield loss caused by increased SCC was found to be mainly related to the early stage of lactation. Depending on the possible scenarios, the estimated milk yield loss from MY305 for primiparous cows was at least 0.8 to 0.9 kg day -1 and for multiparous cows it ranged from 1.3 to 4.3 kg day-1. Thus, the SCCI was a suitable indicator for estimating daily milk yield losses associated with increased SCC and might provide farmers reliable information to take appropriate measures for ensuring good health of cows and reducing milk yield losses at the herd level.
Ključne besede: dairy cows, milk production, lactation intervals, milk yield losses, somatic cell count index
Objavljeno: 24.10.2017; Ogledov: 31; Prenosov: 0
.pdf Polno besedilo (317,33 KB)

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