Avtor/Urednik		Rajčevič, M; Jazbec, I; Sirk, M; Levstek, J
Naslov		The effect of season on the content of urea in milk of cows
Prevedeni naslov		Vpliv letnega obdobja na koncentracijo sečnine v mleku krav
Tip		članek
Vir		Zb Vet Fak Univ Ljublj
Vol. in št.		Letnik 33, št. 2
Leto izdaje		1996
Obseg		str. 247-53
Jezik		eng
Abstrakt		On the two farms (A and B) in two successive years, each year on one farm, nutrition and production of cows followed seasonally. Cows were of Friesian breed and loose housing. Based on determination of milk urea content possible deficient energy supply and excessive protein supply were to dairy cows established. On the farm A, in the summer season (May, June, July and September), cows received with rations from 5 to 19 %, on average 10,2 % more protein, and energy on production need limit. The urea content in milk was from 3.82 to 6.28 mmol/l, on average 5.24 mmol/l. In the winter season (January-April) daily energy needs of cows were covered from 90 to 118 %, on average 99 %, supply with crude protein was from 90 to 135 %, on average 113 %. The milk urea content was from 2.76 to 4.32 mmol/l, on average 3.57 mmol/l. The difference in average milk urea content in the summer and the winter season was 1.67 mmol/l and was statistically highly significant (p = 0.001). On the farm B rations were even more unbalanced. In the summer season (June-September) daily needs of protein were covered from 80 to 145 %, on average 113 %, and energy needs from 81 to 109 %, on average 95 %. The milk urea content was from 6.19 to 10.48 mmol/, on average 7.82 mmol/l. In the winter season excess protein and energy in rations were found. The protein needs of cows were covered from 113 to 148 % on average 131 %, and energy needs from 105 to 128 %, average 116 %. The urea content in milk was from 3.9 do 6.47 mmol/l, on average 5.01 mmol/l, which is far too much for winter season. The difference of 2.81 mmol/l between summer and winter season was statistically highly significant (P = 0.001). On both farms, the established statisticali highly significant differences in urea content between the summer and the winter season were the result of cow nutrition.
Izvleček		Ba dveh farmah (A in B) smo dve zaporedni leti, vsako leto na eni farmi, sezonsko spremljali prehrano in proizvodnjo krav. Krave so črno-bele pasme in v prosti reji. Na osnovi določitev sečine (in beljakovin) v mleku smo ugotavljali možno pomanjkljivo oskrbo molznic z energijo oz. preveliko oskrbljenost z beljakovinami. Na farmi A so krave v poletnem obdobju (maj, junij, julij in september) dobivale z obroki od 5 do 19 %, povrečno 10,2 # več beljakovin, energije pa na meji proizvodnih potreb. Vsebnost sečnice v mleku je bila od 3,82 do 6,28 mmol/l, povrepčno 5,24 mmol/l. V zimskem obdobju (januar-april) so bile dnevne energije potrebe krav pokrite od 90 do 118 %, povprečno 99 %, oskrbljenost s surovinami beljakovinami pa je bila od 90 do 135 %, povprečno 113 %. Vsebnost sečnine v mleku je bila od 2,76 do 4,32 mmol/m, povprečno 3,57 mmol/l. Razlika v povrečni vsebnosti sečnine v mleku v poletnem in zimskem obdobju je 1,67 mmol/l in je statistično visoko značilna (p = 0,001). Na farmi B je bila neuravnoteženost obrokov večja. V poletnem obdobju (junij-september), so bile dnevne potrebe po beljakovinah pokrite od 80 do 145 %, povprečno 113 %, potrebe po energiji pa od 81 do 109 %, povrepčno 95 %. Vsebnost sečnine v mleku je bila od 6,19 do 10,48 mmol/l, povrečno 7,82 mmol/l. V zimskem obdobju smo ugotavljali presežke beljakovin in energije v obrokih. Potrebe krav po beljakovinah so bile pokrite od 113 do 148 %, povrečno 131 %, potrebe po energiji pa 105 do 128 %, povrečno 116 %. Vsebnost sečnine v mleku je bila od 3,9 do 6,47 mmol/l, povrečno 5,01 mmol/l, ka rje za zimsko obdobje prevelika. Razlika 2,81 mmol/l med poletnim in zimskim obdobjem je statistično visoko značilno (p = 0,001). Na obeh farmah ugotavljena statistično visoko značilna v vsebnosti sečnine med poletnim in zimskim obdobjem v naši raziskavi iz prehrane krav.
Deskriptorji		MILK ANIMAL NUTRITION DIET CATTLE UREA MILK PROTEINS SEASONS