Influence of casein and glucose or starch supplementation in the rumen or abomasum on utilization of Eragrostis curvula hay by sheep

Abstract

In one experiment the effects of casein in the abomasum was compared to isonitrogenous quantities of casein or urea in the rumen. In another two experiments the effects of casein in the rumen or abomasum were compared to isocaloric quantities of glucose or starch or to treatments where casein was partially replaced by these carbohydrates. Casein and glucose or starch were administered to the rumen or abomasum twice daily as pulse doses in quantities varying between 30 and 80 g per day. Measurements include voluntary intake of hay, ADG, wool growth, non-ammonia N (NAN) flow to the abomasum, and N-retention. Results suggest that supplementation with casein instead of NPN in the rumen may be beneficial. Secondly, postruminal administration of casein increased ADG, wool growth and, on occasion, hay intake. Postruminal administered casein furthermore, increased NAN flow to the abomasum and N-retention. Thirdly, glucose or starch supplementation to the rumen or abomasum alone was not beneficial in terms of ADG, wool growth and N-retention. It is concluded that indispensable amino acids at the tissue level of sheep are limiting with such forages, rather than energy - a fact which should be taken into account with supplementation in practice.

In een eksperiment is die invloed van kaseïen in die abomasum vergelyk met isostikstof hoeveelhede kaseïen of ureum in die rumen. In twee verdere eksperimente is die invloed van kaseïen in die rumen of abomasum vergelyk met isokaloriese hoeveelhede glukose of stysel, of met behandelings waar kaseïen gedeeltelik verplaas is deur genoemde twee koolhidrate. Kaseïen en glukose of stysel is deur die rumen- of abomasale kanule twee keer per dag in enkel dosisse toegedien, teen hoeveelhede wat tussen 30- en 80 g per dag gewissel het. Vrywillige inname van hooi, GDT, wolgroei, nie-ammoniak-N(NAN)-vloei na die abomasum en N-retensie is gemeet. Die resultate dui daarop dat supplementering met kaseïen eerder as met NPN in die rumen voordele kan inhou. Tweedens, het abomasale toediening van kaseïen GDT, wolgroei en soms hooi-inname, verbeter. Verder het dit ook NAN-vloei na die abomasum en N-retensie verhoog. Derdens, was toediening van glukose of stysel in die rumen of abomasum alleen nie voordelig in terme van GDT, wolgroei of N-retensie nie. Die gevolgtrekking is gemaak dat onontbeerlike aminosure op weefselvlak van skape by hierdie tipe ruvoere be perkend is, eerder as energie, - 'n feit wat met supplementering in die praktyk in gedagte gehou moet word.

Keywords: Casein, Eragrostis curvula, glucose, sheep, starch, supplementation.