Introduction opposite the ileo-caecal valve. Once the cannula is

134 Y .-L. Yin et al. Livestock Production Science 62 2000 133 –141

1. Introduction opposite the ileo-caecal valve. Once the cannula is

opened the valve protrudes into the cannula and Since the 1970s, many studies have been per- digesta can be sampled as it leaves the ileum. Recent formed to estimate ileal digestibility using different studies showed that PVTC has a number of advan- methods for digesta collection. These have been tages over the simple ‘‘T’’cannulation methods van ¨ reviewed by Sauer and Ozimek 1986, Fuller 1991 Leeuwen et al., 1991. Kohler et al. 1991 compared and Yin and McCracken 1996. The methods three different cannulation techniques and reported frequently applied for quantitative collection are re- higher ileal Cr O recovery and digestibility values 2 3 entrant cannulation, end-to-end ileorectal anas- with the re-entrant techniques than with the PVTC or tomosis IRA or the steered ileo-caecal valve simple ileal ‘‘T’’ cannula. However, with all three SICV technique Mroz et al., 1996. These meth- methods Cr O recovery was less than 100. The 2 3 ods are generally regarded as more accurate for authors concluded that the results showed less vari- measuring ileal digestibility of nutrients, since they ation with the PVTC cannula compared with the involve the total collection of ileal digesta and it is simple ileal ‘‘T’’ cannula. Therefore on this basis, unnecessary to use a marker, such as chromic oxide. and in view of the simplicity of handling, the PVTC However, the re-entrant cannulation technique poses cannula appears to be a good alternative to the other problems in that it interrupts the transport of the methods. The results from Yin et al. 1999 indicated normal migrating myoeletric complex which is that the post-valvular ‘‘T’’-caecum cannula method necessary for normal digesta passage Laplace, 1980; is a more precise and less labour intensive technique Low, 1982; Sauer and Ozimek, 1986; Fuller, 1991. for ileal digestibility studies than the simple ileal ¨ This method is also generally associated with block- ‘‘T’’ cannula. Furthermore Kohler et al. 1991 and age of the cannula by coarsely ground or fibrous Yin et al. 2000 suggested that the PVTC method is diets which prevents its use with many feed com- almost a quantitative collection method. However ponents. With the IRA method, normal functioning this aspect requires further investigation. of the large intestine is obviously not maintained and The low recovery of markers in faeces reported by this may have an influence on the water and mineral Mueller 1956, Moore 1957, 1959, Ishikawa ¨ absorption and on growth Kohler et al., 1991. 1966, Ishikawa and Sugimura 1973, Moughan et However, Hennig et al. 1986, 1992 and Yin et al. al. 1991, Greer 1992 and McClean 1993 is a 1993 reported that the loss of the function of the major cause for concern. Barnicoat 1945, Moore large intestine can be compensated by supplying the 1957, 1959, McClean 1993 and Yin et al. 2000 animal with large amounts of water, minerals and suggested that this may be due to retention and or vitamins and Laplace et al. 1994 showed that the absorption in the large intestine. end-to end procedure was preferable to the end-to- Although chromic oxide is frequently used as a ¨ side operation used by Kohler et al. 1991. There is marker in pig digestibility studies, some authors have ample evidence, therefore, that the IRA method can found that recoveries are variable, less than 100 be used for measurement of ileal digestibility of dry and that this material may have carcinogenic prop- matter, crude protein, energy and amino acids no erties Mueller, 1956; Moore, 1957; Peddie et al., simultaneous information on faecal digestibility is 1982; Jagger et al., 1992; Monaghan, 1996. Data obtained. The SICV method appears to have some from ileal digestibility studies have indicated that advantages but has not yet been widely tested and no chromic oxide may move out of phase with digesta, ¨ direct comparisons with the IRA method are avail- particularly when fibrous diets are fed Kohler et al., able since the use of the latter is prohibited in the 1990. The problems encountered with Cr O led to 2 3 Netherlands. its replacement by some workers with other markers, Methods frequently applied for partial-sampling e.g., titanium dioxide and acid-insoluble ash Jagger involving the use of a marker include the simple ileal et al., 1992; McCarthy et al., 1974; Moughan et al., ‘‘T’’ and post-valve ‘‘T’’ caecal cannulae PVTC. 1991; Njaa, 1961; van Leeuwen et al., 1996. Unlike the simple ileal ‘‘T’’ cannula method, with Titanium dioxide has been used successfully as an the PVTC technique the caecum is partially removed indicator in digestibility studies with rats, chickens and replaced by the PVTC cannula, which is placed and pigs Njaa, 1961; Peddie et al., 1982; Jagger et Y .-L. Yin et al. Livestock Production Science 62 2000 133 –141 135 al., 1992. However, there is little information about crude protein CP, energy and amino acids AAs the use of TiO as a marker for determination of the were calculated for the two experiments. Ileal re- 2 ileal digestibility of nutrients in pigs. covery of TiO and Cr O and IAD of DM, CP, 2 2 3 The present studies afforded the opportunity to 1 gross energy and amino acids measured with TiO 2 compare the use of Cr O and TiO as indigestible and Cr O were compared by Student’s t-test. In 2 3 2 2 3 markers, 2 compare the PVTC with the IRA order to compare three methods PVTC TiO 2 method, 3 evaluate the PVTC method for quantita- marker, PVTC Cr O marker and PVTC total collec- 2 3 tive collection of digesta, using wheat and its by- tion, the 144 data values corresponding to 12 pigs 3 product-based diets with a range of fibre content. 4 periods 3 3 methods were analysed using a split plot model with diets as the main plot factor and methods as the sub-plot factors. The analysis was

2. Materials and methods carried out using the REML procedure of the Genstat