An assessment of the use of chromic oxide as a marker in protein digestibility studies with Haliotis midae L.

Gastrointestinal evacuation time, but not nutrient digestibility, of greenlip abalone, Haliotis laevigata Donovan, is affected by water temperature and age

“…Generally, with the second type of faecal pellets, the green with a white stripe was initially observed as the marker diet was initially voided and the white with a green stripe appeared as marker diet began reaching the end of evacuation. Only two out of three types of faeces described for Haliotis rubra by Wee et al (1992) and H. midae by Shipton and Britz (2001) were observed. Two types observed were discrete whole pellets and long, thin strings.…”

“…These methods include dissection (Miegel et al, 2010), stripping (Storebakken, 1985), inert markers (Boyce et al, 2000;Richter et al, 2008;Storebakken et al, 1999), radioactive isotopes (Storebakken et al, 1981), radiography (Hossain et al, 2000;Jobling, 1987;Jobling et al, 1977;Tablot and Higgins, 1983) and faecal collection by settlement (Sales and Britz, 2001;Shipton and Britz, 2001). Due to handling logistics, only faecal collection by settlement and radiography may be suitable methods for the determination of GIE time in abalone.…”

“…Due to handling logistics, only faecal collection by settlement and radiography may be suitable methods for the determination of GIE time in abalone. Digestibility studies may also be carried out using faecal collection by settlement (Sales and Britz, 2001;Shipton and Britz, 2001;Vandepeer et al, 2002); therefore, using methods in which both studies can be employed simultaneously would be beneficial in order to refine future studies for this species.…”

“…South African abalone (Haliotis midae L) have been shown to have a gastric evacuation time of 18 to 24 h when fed a formulated diet (Britz et al, 1996), and produced faeces up to 96 h after being fed a formulated feed with 0.5 % chromic oxide as a marker (Shipton and Britz, 2001). When H. midae are fed algae, less digestible algal species remain identifiable in the stomach for more than 48 h, whereas preferred algal species are mostly digested within 24 h (Day and Cook, 1995).…”

“…When H. midae are fed algae, less digestible algal species remain identifiable in the stomach for more than 48 h, whereas preferred algal species are mostly digested within 24 h (Day and Cook, 1995). A problem with these studies is that the animals were fasted for three days (Britz et al, 1996), four days (Sales and Britz, 2001;Shipton and Britz, 2001) or four weeks (Day and Cook, 1995) prior to feeding the test diet. Additionally, after receiving their test ration, the abalone in these studies were also fasted for the remainder of the experiment.…”