Differences between sheep and red deer in in vitro apparent and true digestibility of commonly used red deer feeds

Abstract

The nutritive value of red deer feeds is frequently determined by sheep despite the ultimate arbitrator of the nutritive value of any feed is the host animal. The objective of the trial was to determine the influence of rumen fluid donor (sheep vs red deer) on in vitro dry matter (DMD), neutral-detergent fibre (NDFD) and true digestibility (ivTD) of eleven substrata, naturally occurring in Slovenian forests (chestnut fruits, acorns of common and sessile oak, two fresh grasses) and those frequently used in supplemental red deer feeding (two grass hays and two grass silages, apple pomace and sugar beet roots). Only the fresh grass from Jelendol had greater (p < 0.05) DMD (646 vs 508 g/kg) when incubated in red deer inoculum. The NDFD and ivTD were always numerically greater when substrates were incubated in red deer inocula, however the NDFD and ivTD were significantly greater (p < 0.05) only when fresh grass from Jelendol (590 vs 343 g/kg and 801 vs 681 g/kg, respectively), grass silage from Kokra (541 vs 359 g/kg and 742 vs 639 g/kg, respectively) and apple pomace (428 vs 328 g/kg and 704 vs 653 g/kg, respectively) were incubated in the inoculum prepared from red deer rumen contents. These results indicate that rumen fluid from sheep can be used to predict in vitro digestibility in red deer and that these parameters can be used in the formulation of deer diets.