Faculty of Veterinary Medicine University of Zagreb
Abstract
The effects of higher levels of chromium alone, and in combination with copper, were investigated in broiler chicks divided into seven equal groups. Group G served as control, receiving no treatment. Groups A, B and F received chromium chloride at a rate of 2 g/kg and nicotinic acid 150 mg/kg, while groups C, D and E received chromium chloride 8 mg/kg and nicotinic acid 150 mg/kg. Broilers in groups A and C received copper sulfate at a rate of 200 mg/kg, while groups B and D received 400 mg/kg feed. Both live and carcass mass showed non-significant difference between treatment groups and control during the treatment period. However, during the withdrawal period these were higher (P<0.05) in chromium-fed birds (alone and in combination). Feed conversion ratio (FCR) was better in the treatment groups. Relative mass of liver to body mass during the first two weeks showed lower (P<0.05) values in birds fed low levels of chromium alone, or in combination with two levels of copper, and those fed high levels of both compounds, compared with control. At the third week the relative mass of liver to body mass was high in all treatment groups than in the control. Relative mass of lung to body mass showed a significant increase in birds fed higher levels of both chromium and copper during the early period, whereas it decreased significantly after the third week than in the control group. During the withdrawal period, relative mass of kidney, lung and heart to body mass were lower (P<0.05) in birds fed chromium alone. Relative heart mass to body mass during termination of treatment showed a significant relationship with relative liver (0.99, P<0.05) and lung (0.99, P<0.05) mass to body mass in the low chromiumfed group, while during the withdrawal period a significant relationship developed of relative heart mass with relative liver (0.99, P<0.05) and lung (0.78, P<0.05) mass to body mass in birds fed high chromium with high copper. Both gross and histological studies showed no change in any organ studied.Istražen je učinak većih razina samog kroma i u kombinaciji s bakrom na zdravlje i proizvodnost tovnih pilića. Pilići u skupinama A, B i F bili su hranjeni hranom u koju je bio umiješan krom u obliku krom klorida u količini od 2 g/kg te nikotinska kiselina u količini od 150 mg/kg. C, D i E skupine bile su hranjene hranom u koju je primiješan krom klorid u količini od 8 mg/kg te nikotinska kiselina u količini od 150 mg/kg. Pilićima skupine A i C bio je primiješan bakreni sulfat u dozi od 200 mg/kg, dok je skupinama B i D primiješan bakreni sulfat u dozi od 400 mg/kg. Težine pilića pokusnih skupina nisu se znatno razlikovale u odnosu na kontrolu, iako su u razdoblju bez primjene bile više u ptica hranjenih kromom odnosno onih kromom i bakrenim sulfatom. Konverzija hrane bila je bolja u pokusnih skupina u odnosu na kontrolu. Relativna težina jetre u odnosu na težinu tijela tijekom prva dva tjedna bila je niža (P<0,05) u svim skupinama bez obzira na razinu kroma i bakra. U trećem tjednu relativna težina jetre je porasla u svim pokusnim skupinama u odnosu na kontrolnu. Relativna težina pluća u odnosu na ukupnu težinu bila je veća nakon primjene visokih razina kroma i bakra u ranom razdoblju. Ona se znatno smanjila u trećem tjednu. Tijekom razdoblja uskraćivanja relativna težina bubrega, pluća i srca u odnosu na tjelesnu težinu bila je niža (P<0,005) u ptica koje su dobivale samo krom. Relativna težina srca u odnosu na tjelesnu težinu pri kraju primjene odgovarala je relativnoj težini jetre (0,99, P<0,05) i pluća (0,99, P<0,05) ptica u skupini koja je dobivala manje kroma. U razdoblju bez primjene uočena je povezanost relativne težine srca s relativnom težinom jetre (0,99, P<0,05 ) i pluća (0,78, P<0,05) u ptica hranjenih visokim razinama kroma i bakra. Patološkoanatomskom i histološkom analizom nisu dokazane nikakve promjene
