VARIATION IN NUTRITIVE VALUE BETWEEN FOUR HALOPHYTIC SHRUB SPECIES COLLECTED FROM FIVE SALINE ENVIRONMENTS

Abstract

Three species of saltbush (A. amnicola, A. nummularia and A. undulata) and bluebush were collected from five sites in Western Australia (Dalwallinu, Meckering, Tammin, Katanning and Lake Grace) that had previously been established to saline pastures, although not all species were present at all 5 sites. Five individual plants of each species were randomly selected from within a 2500 m 2 area for the collection of leaf material. The leaf material was analysed for the following attributes; in vitro and in sacco digestibility of the organic matter in the dry matter (DOMD), ash and insoluble ash content, acid detergent fibre (ADF), neutral detergent fibre (NDF) and nitrogen (N) content. In vitro digestibility was determined using a modified Klein and Baker (1993) pepsin-cellulase procedure. These in vitro measurements were not calibrated for in vivo digestibility due to a lack of reliable calibration standards from diets containing high salt. Since not all species were present at each site, an analysis of variance using unbalanced treatments was used. Table 1 provides data on the nutritional attributes of the 4 halophytes. Bluebush tended to accumulate more ash and insoluble ash than the 3 saltbush species. Atriplex nummularia contained higher concentrations of N and was more digestible than the other species. However, A. amnicola and A. undulata had higher ADF and NDF concentrations. Considering the standard deviations, it was apparent that there was variability within the 4 species of halophytes, with A. amnicola and A. undulata showing greatest differences in both in vitro and in sacco digestibility, and ash content. However, the reasons for such differences could not be determined. Table 1. Nutritional attributes (means (% of DM) ± s.d.) of 4 halophytes (see the text for details).