 effect rumin insuffl cerebr circul metabol goat effect nitrogen insuffl cannul rumen studi 10 goat paramet measur includ cerebr blood flow carotid arteri pressur pressur confluenc sinus cerebrospin fluid pressur blood oxygen carbon dioxid content pack cell volum pcv hemoglobin concentr valu cerebrovascular resist cerebr util calcul increas rumin pressur cerebr blood flow cerebrovascular resist cerebr util decreas intrarumin pressur increas decreas caus reduct arteri content consequ decreas cerebr arterioven differ arteri venou sinu cerebrospin fluid pressur increas intrarumin pressur increas increas pcv hemoglobin concentr elev intrarumin pressur central nervou system sign goat acut rumin tympani caus cerebr hypoxia natur hypertens chang associ increas rumin pressur demonstr influenc multipl factor fluid compart conclus mechan pressur respons mechan factor involv 