Uticaj energetskog bilansa na endokrini i metabolički status krava

Abstract

Cilj ove doktorske disertacije je bio da se ispita uticaj energetskog dodatka na bazi glicerola na metabolički i endokrini status krava u kasnom graviditetu i ranoj laktaciji. Ispitivanja su izvršena na 60 krava odabranih u zasušenju podeljenih u dve jednake grupe. Obe grupe su dobijale potpuno izmešan obrok dva puta dnevno koji je bio usklađen sa potrebama jedinki u odnosu na fazu proizvodno reproduktivnog ciklusa. Dodatno, krave ogledne grupe su u jutarnjem obroku dobijale energetski dodatak u količini od 250 ml u periodu zasušenja, odnosno od 15. dana pre očekivanog termina teljenja do momenta teljenja, i u količini od 300 ml u periodu rane laktacije, odnosno prvih 60 dana posle teljenja, čime im je obezbeđeno dodatnih 9,30 MJ NEL tokom zasušenja, odnosno 13,95 MJ NEL tokom rane laktacije. Kontrolna grupa krava nije primala energetski dodatak. Telesna kondicija krava određena je 15. dana pre i 7., 30. i 60. dana posle teljenja. Sedmog, tridesetog i šezdesetog. dana nakon teljenja zabeležena je dnevna proizvodnja mleka. Od reproduktivnih pokazatelja registrovani su servis period i indeks osemenjavanja. Uzorci krvi za analizu uzimani su od krava punkcijom vene jugularis 15. dana pre , kao i 7. 30 i 60. dana nakon teljenja. U uzorcima krvi određivani su koncentracije glukoze, beta-hidroksi buterne kiseline (BHBA), neesterifikovanih masnih kiselina (NEFA), ukupnih proteina, albumina, uree, ukupnog bilirubina, kalcijuma, fosfora, insulina, trijodtironina, tiroksina, IGF-I i zastupljenost IGFBP-2, -3 i -4. Uzorci tkiva jetre su uzeti 7., 30. i 60. dana laktacije i u njima je određivan sadržaj ukupnih lipida.Računski su dobijeni HOMA (homeostatic model assessment) indeks i odnos T3 i T4. Krave ogledne grupe su u odnosu na kontrolnu imale značajno višu vrednost ocene telesne kondicije 7 dana nakon teljenja. Proizvodnja mleka kod krava ogledne grupe je bila značajno viša 60. dana laktacije. Krave koje su primale energetski dodatak su imale značajno kraći servis period u odnosu na kontrolnu grupu. Prosečni stepen zamašćenja jetre je 7. dana laktacije kod kontrolne grupe bio srednji a kod ogledne nizak. Tridesetog dana laktacije stepen zamašćenja jetre je bio značajno niži kod ogledne u odnosu na kontrolnu grupu, dok 60. dana ni kod jedne grupe nisu utvrđene masne kapljice u jetri...

The aim of this PhD thesis was to examine the effect of glycerol based energy supplementation on metabolic and endocrine status of cows in late pregnancy and early lactation. The study was conducted on a total of 60 cows, selected in dry period and divided into two groups. Both groups of cows were fed with a total mix ratio adjusted to the nutritive needs for pregnancy and lactation. Additionally, each cow in the experimental group was given energy supplement dispersed in the morning feed by sprayer for the period of the experiment in the quantity of 250 mL during last 15 days of pregnancy and 300 mL during first 60 days of lactation. Added glycerol provided additional 9.30 MJ NEL during dry period and additional 13.95 MJ NEL during early lactation period. Control animals did not receive energy supplement. Body condition score was performed at day 15 before and days 7, 30 and 60 after calving. Milking was measured at days 7, 30 and 60 of lactation. Service period and insemination index were determined. Four blood samples were taken by jugular venipuncture from each animal at day 15 before and days 7, 30 and 60 after calving. The blood glucose, beta-hydroxi butirate (BHBA), non-esterified fatty acid (NEFA), total protein, albumin, urea, total bilirubin, Ca, P, insulin, triiodothyroinine, thyroxine, IGF-I as well as relative abundance of IGFBP-2, -3 and - were measured. Liver percutaneous biopsies were obtained at days 7, 30 and 60 after calving and total lipid content in hepatocites was measured. At day 7 after calving, cows from experimental group had significantlly higher values for body condition scores than cows from control group. Experimental group of cows had significantlly higher milk production than control group at day 60 of lactation. Energy supplemented cows had significantlly shorter service period than control group. At day 7 of lactation, average degree of fatty liver was moderate in cows of control group and mild in cows from experimental group. At day 30 of lactation exerimental group of cows had significantlly lower fatty liver digree then control group. At day 60 of lactation there was no fat droplets in hepatocites of cows from both groups. Concentrations of blood measured biochemical and hormone parameters did not significantlly differ between two groups at dry period, meanining before the biggining of experiment...