The effect of ruminal and duodenal application of different levels of calcium and phosphorus to sheep on semi-purified diets

Abstract

Nege behandelings van Ca_oP_o, Ca_r, Ca_d, P_d, (CAP)_r, Ca_dP_r, (CaP)_d en Ca_rP_d (o = geen supplementasie; r -= aan rumen en d = aan duodenum) is ondersoek. P-supplementasie onderdruk Ca-absorpsie en -retensie en omgekeerd. P-absorpsie in duodenum is konsentrasie-afhanklik en Ca- en anolgllniese P-konsentrasie in die rumen is afhanklik van die inname: Ca meer so as P. Serum-Ca was betreklik konstant terwyl serum anorganiese P (P_i) beduidend deur die behandelings beinvloed is. Ca- en P-onderhoudsbehoeftes kan as 3,0 en 1,8 g/dag en die totale endogene verlies 0,5 en ongeveer 0,34 g/dag onderskeidelik beskou word. Die Ca/p verhouding vir die rumen-mikro-organismes is nie krities
nie maar die Ca-peil mag gewoonweg meer krities as die P-peil in die rumen wees. 'n'Wye Ca/P verhouding vir herkouers is aan te beveel. Konsentrasies
van P_i en vetsure in rumenvloeistof is betekenisvol gekorreleerd sowel as rumen-Ca met vetsure en TCA-N.

The effect of different levels and combinations of Ca and P consisting of nine treatments as Ca_oP_o, Ca_r, P_r,Ca_d, P_d, (CaP)_r, Ca_dP_r, (CaP)_d and Ca_rP_d were investigated with an unrestricted semi-purified diet (r = to the rumen; d = to the duodenum, and o = no supplementation). P supplementation, irrespective of site, depressed Ca absorption and retention and vice versa. P absorption is favoured by high concentrations in the duodenum, absorption thus being concentration dependent. Ca and inorganic P (P_i) concentration in rumen liquor is
intake dependent; the former more so than the latter. The serum Ca was relatively stable despite treatment differences, whereas serum P_i concentration
was significantly affected by treatments. Serum Ca and P_i are negatively correlated (r = -0,5307). Car resulted in the highest concentration
of serum Ca but depressed serum P_i more effectively than e.g. Ca_oP_o and Ca_d. The Ca and P maintenance requirements were found to be 3,0 and 1,8 g/day and the endogenous loss 0,5 and approximately 0,34 g/day respectively. The Ca/P ratio for the rumen microorganisms is not critical but the rumen Ca level may usually be of a more critical nature in contrast to rumen P_i levels, and thus, favouring a wider ratio than is usually recommended for non-ruminants. Concentrations of rumen liquor P_i and VFA were found to be significantly associated as well as rumen Ca with VFA and TCA-N, respectively.