@article{
author = "Adamović, Milan and Šamanc, Horea and Kirovski, Danijela and Vujanac, Ivan and Valčić, Olivera",
year = "2014",
abstract = "The objective of the work was to investigate the influence of partial substitution of magnesium oxide with natural bentonite in feed mixtures used in feeding of cows during their exposure to heat stress. The investigation lasted 30 days and was carried out during last ten days of may and first twenty days of June when average air temperature in stables was 36.6±2.5oC. In the experiment there were included 30 cows of Holstein breed in first phase of lactation, which were divided into two groups of 15 cows: control (C) and experimental (E). Group C was fed with experimental mineral mixture that contained 60% of magnesium oxide during the whole investigation period. Group E was fed with experimental mineral mixture that contained 40% of magnesium oxide as well as 20% of natural bentonite. Remaining ingredients in both control and experimental mineral mixtures were the same and also contained 20% of sodium bicarbonate and 20% of zeolite in the same quantities. The control and experimental mineral mixtures were mixed into complete feed mixture (18% UP) in the amount of 1%. At the end of the investigation period, on the 30th day, there were taken samples of rumens contents for determining pH, and after that blood samples, in which, after the separation of blood serum, were determined glucose concentration, total proteins, albumin, globulin, urea, HDL cholesterol, LDL cholesterol, total bilirubin, calcium and phosphorus, as well as the activity of ALT and AST By computation there was calculated the ratio between albumin and globulin, ALT and AST, and the ratio between calcium and phosphorus. Daily allowance and milk chemical composition ( percentage of fat, proteins and dry substance) were determined at the end of the investigation period, that is on the 30th day of lactation, for each cow individually. Partial substitution of magnesium oxide with bentonite influenced milk production increase, but it was statistically insignificant. Besides that, in E group of cows, percentage of fat and dry substance in milk was significantly increased (p lt 0.05 and 0.01 respectively), while percentage of protein increase was insignificant. The substitution of magnesium oxide with bentonite had no impact on the values of examined parameters of metabolic profile, but it led to statistically significant increase of rumen contents pH values (p lt 0.05). From the obtained results it can be concluded that substitution of magnesium oxide with bentonite in feed mixtures that are used for feeding cows during summer period, can prevent rumen acidosis, which high yielding cows incline to under the conditions of elevated external temperatures. Besides that, this kind of substitution leads to improvement of milk composition, especially when percentage of fat and dry substance in milk is concerned., Cilj ovog rada bio je da se ispita uticaj delimične supstitucije magnezijum oksida prirodnim bentonitom u krmnim smešama korišćenih u ishrani krava tokom njihove izloženosti toplotnom stresu. Ispitivanje je trajalo 30 dana i izvedeno je tokom poslednjih deset dana maja i prvih dvadeset dana juna kada je prosečna temperatura vazduha u staji bila 36,6 ± 2,5oC. U ogled je bilo uključeno 30 krava holštajn rase u prvoj fazi laktacije, koje su podeljene u dve grupe od po 15 krava: kontrolnu (K) i eksperimentalnu (E). K grupa je tokom celog ispitivanog perioda hranjena kontrolnom mineralnom smešom koja je sadržavala 60% magnezijum oksida. E grupa je bila hranjena oglednom mineralnom smešom koja je sadržavala 40% magnezijum oksida i 20% prirodnog bentonita. Preostali sastojci u kontrolnoj i oglednoj mineralnoj smeši bili su isti i u istim količinama i sadržavali su 20% natrijum bikarbonata i 20% zeolita. Kontrolna i ogledna mineralna smeša bile su umešane u potpunu krmnu smešu (18% UP) u iznosu od 1%. Na kraju oglednog perioda, 30. dana, uzeti su uzorci sadržaja buraga za određivanje pH a nakon toga i uzorci krvi u kojima su, nakon odvajanja krvnog seruma, određeni koncentracje glukoze, ukupnih proteina, albumina, globulina, uree, HDL-holesterola, LDL-holesterola, ukupnog bilirubina, kalcijuma i fosfora, kao i aktivnost ALT i AST. Računskim putem su obračunati odnosi albumina i globulina, ALT i AST, kao i odnos kalcijuma i fosfora. Dnevna količina i hemijski sastav mleka (procenat masti, proteina i suve materije) za svaku kravu pojedinačno određeni su na kraju ispitivanog perioda, odnosno 30. dana laktacije. Delimična supstitucija magnezijum oksida bentonitom je uticala na povećanje proizvodnje mleka ali ovaj porast nije bio statistički značajan. Pored toga kod E grupe krava procenat masti i suve materije u mleku bio je značajno povećan (p lt 0,05 odnosno 0,01), dok porast procenta proteina nije bio značajan. Zamena magnezijum oksida bentonitom nije uticala na vrednosti ispitivanih parametara metaboličkog profila ali je dovela do statistički značajnog povećanja pH vrednosti sadržaja buraga (p lt 0,05). Iz dobijenih rezultata se zaključuje da zamena magnezijum oksida bentonitom u krmnim smešama koje se koriste za ishranu krava tokom letnjeg perioda može preventivno da utiče na pojavu acidoze buraga kojoj su visokomlečne krave sklone u uslovima povišenih spoljašnjih temperatura. Pored toga, ovakva supstitucija dovodi do poboljšanja sastava mleka i to značajno u slučaju procenta masti i suve materije u mleku.",
publisher = "Univerzitet u Beogradu - Fakultet veterinarske medicine, Beograd",
journal = "Veterinarski Glasnik",
title = "Effects of buffering mineral mixtures on milk yield, milk composition, rumen pH and some blood biochemical parameters in heat stressed dairy cows, Vlijanie mineral'noj smesi s bufernym dejstviem na nadoj moloka, sostav moloka, rN soderžanie rubca i koncentraciju nekotoryh biohemičeskih pokazatelej krovi u korov, podvergšihsja vozdejstviju teplovogo stressa, Uticaj mineralnih smeša sa pufernim dejstvom na mlečnost, sastav mleka, pH sadržaja buraga i koncentraciju pojedinih biohemijskih parametara krvi krava izloženih toplotnom stresu",
volume = "68",
number = "1-2",
pages = "31-42",
doi = "10.2298/VETGL1402031A"
}
