In vitro digestibility using caecal liquor of diets containing poor quality roughages and green forages fed to domesticated ostriches ( Struthio camelus var. domesticus)

Abstract

The objective of this study was to compare in vitro organic matter digestibility (IVOMD) of ostrich diets using the normal (NTT) and reverse (RTT) modified Tilley and Terry methods of in vitro digestion. The IVOMD values of green forages were determined using the RTT method only. Four ostrich diets and four green forages were digested in vitro using caecal liquor collected from ostriches slaughtered at the Norton Commercial ostrich producers (Copro) abattoir. The diets included a control diet of a concentrate and legume hay, silverleaf desmodium uncinatum (CN), and the three others consisting of a concentrate with either veld hay (VH), Katambora Rhodes grass hay (RG) or maize stover (MS). Lucerne (LU), Midmar Rye grass (MRG), Russian Comfrey (RC) and Kenyan White clover (KWC) were the green forages used. The forages were grown under the recommended management levels and were cut before flowering. There was no interaction ( P>0.05) between diet and method of digestion. The RTT gave higher ( P<0.01) IVOMD than the NTT method. However, both methods showed a similar trend in the digestion of the diets. The MS and RG diets had similar and greater ( P<0.05) IVOMD than the control and veld hay diets. The amounts of organic matter (OM) digested differed ( P<0.01) with either diet or forage type. Kenyan White clover and MRG had similar and greater ( P<0.05) IVOMD than LU and RC, which were not different ( P>0.05). The values of IVOMD in dry matter for the forages were: MRG > KWC > LU > RC, and all the differences were significant ( P<0.05). The study showed that the NTT method needs to be modified to suit hind gut fermenters and IVOMD can, therefore, be used to rank the nutritive value of ostrich feeds.