[Concentration of urea in milk and energy status of high-yielding dairy cows. M.Sc. thesis] | Koncentracija ureje u mleku i energetski status visoko-mlečnih krava. Magistarska teza
2009
Stojanović, G.
The purpose of this study was to conduct the examination of qualitative and quantitative relation of milk biochemical ingredients (urea, total proteins and fats) in order to gain better knowledge of energetic state of highly-milky cows and take appropriate measures and also, to prevent various health disorders originating from negative energy balance. The examinations were conducted on three big farms and 10 mini farms. From each big farm 30 cows of Holstein-Friesian breed were selected in the early phase of lactation (first 60 days of lactation). The selected cows were from first to fifth lactation. Out of all mini farms a total number of 46 Simmental cows were selected, from first to sixth lactation. Average milk yield on big farms was 27.5 liters/a day, and on mini farms it was 22.5 liters/a day. Feeding of cows on all farms was based on meals recommended for that category of cows. Body condition of cows included in these examinations was assessed according to system Elanco Animal Health Buletin Al 8478. Based on the results of the ratio between urea concentration and protein content in cows milk from big farms as well as mini farms, protein sufficiency was determined in majority of cows, followed either by energy deficiency or normal share of energy in the meal. Ratio analysis of fat and protein content in milk confirmed energy deficiency in majority of cows on big examined farms and in small number of Simmental cows from mini farms.
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