www.elsevier.com / locate / livprodsci
Apparent digestibility (ileal and overall) of nutrients as
evaluated with PVTC-cannulated or ileo-rectal anastomised pigs
fed diets containing two indigestible markers
a ,1 c d e e
Y.-L. Yin
, J.D.G. McEvoy , H. Schulze , U. Hennig , W.-B. Souffrant ,
a,b ,*
K.J. McCracken
a
Department of Agricultural and Environmental Science, The Queen’s University of Belfast, Newforge Lane, Belfast BT9 5PX, Northern Ireland, UK
b
Department of Agriculture for Northern Ireland, Newforge Lane, Belfast BT9 5PX, UK
c
Veterinary Sciences, Department of Agriculture for Northern Ireland, Stoney Road, Belfast BT4 3SD, Northern Ireland, UK
d
Finnfeeds International Ltd., Marlborough, Wiltshire SN8 1AA, UK
e
¨ ¨
Forschungsbereich Ernahrungsphysiologie‘‘Oskar Kellner’’, Forschungsinstitut f ur die Biologie Landwirtschaftlicher Nutztiere, Rostock, Germany
Received 28 July 1998; received in revised form 3 February 1999; accepted 15 June 1999
Abstract
The techniques of post-valve ‘‘T’’ caecal cannulation (PVTC) and ileo-rectal anastomosis (IRA) and the indigestible markers Cr O and TiO for determination of ileal digestibility of nutrients were studied in this experiment. The results2 3 2
showed that the marker Cr O2 3 gave consistently lower ileal recovery and ileal apparent digestibility of nutrients. The average value of ileal recovery of Cr O measured with the IRA method was only 87%. A nearly 100% of ileal recovery of2 3
TiO measured with the IRA method suggests that the use of TiO as a marker may be a better choice for determination of2 2 ileal digestibility of nutrients when partial-sampling ileal digesta. The reason for the lower ileal recovery of Cr O may be2 3
due to the chemical analytical problems of Cr in excreta. The low recoveries of markers (TiO 67.8% and Cr O 60.6%) and2 2 3 the high values for ileal digestibility of nutrients in the high fibre content diet based on wheat bran (WB) measured by the PVTC total collection method indicated that a quantitative collection of digesta had not been achieved and hence that it is necessary to use a marker for the PVTC method. However, the results from the present experiment showed that there is a high ileal recovery of TiO (95–100%) for the low and medium fibre diets based on wheat (W), recombined wheat (flour2 plus bran plus middlings, WR) and wheat middlings (WM) measured by the PVTC method. The ileal digestibility of nutrients measured by PVTC (TiO ) agreed well with the IRA method for all of the for measuring the ileal digestibility of2 nutrients in pigs. 2000 Elsevier Science B.V. All rights reserved.
Keywords: Ileal digestibility; Indigestible markers; PVTC-cannulation; Ileo-rectal anastomised pigs
*Corresponding author. Corresponding address: Agricultural and Environmental Science Division, Agriculture and Food Science Centre, Newforge Lane, Belfast BT9 5PX, Northern Ireland, UK. Tel.: 144-1232-255-368; fax: 144-1232-662-007.
E-mail address: [email protected] (K.J. McCracken)
1
Present address: Department of Animal Science, University of Manitoba, Winnipeg R3T 2N2, Canada.
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 values2 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%. The2 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 to2 3
Netherlands. its replacement by some workers with other markers,
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 the2 were calculated for the two experiments. Ileal re-ileal digestibility of nutrients in pigs. covery of TiO2 and Cr O2 3 and IAD of DM, CP, The present studies afforded the opportunity to (1) gross energy and amino acids measured with TiO2 compare the use of Cr O and TiO as indigestible2 3 2 and Cr O2 3 were compared by Student’s t-test. In markers, (2) compare the PVTC with the IRA order to compare three methods (PVTC TiO2 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 pigs3 product-based diets with a range of fibre content. 4 periods33 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
5 Committee (1993). Because of the differences in Two separate studies were conducted. In experi- location, pig breed and statistical design no statistical ment 1, 12 Large White Landrace boars, approxi- comparison of the PVTC and IRA techniques was mately 26 kg, were fitted with post-valve ‘‘T’’ caecal considered valid.
cannulae (PVTC) according to the procedures of van Leeuwen et al. (1991). The pigs were randomly allocated, in a four-period crossover design to eight
3. Results
diets based on wheat (W), wheat plus middlings (WM), wheat plus bran (WB) or recombined wheat
3.1. Ileal recoveries of TiO and Cr O2 2 3 (flour plus bran plus middlings, WR) without or with
xylanase addition. Each of the four main diets was
The ileal TiO2 and Cr O2 3 recoveries for the mixed as a single batch and then divided for enzyme
experimental diets W, WR,WM and WB and the addition. The diets, which contained both TiO and2 average values are given in Table 1. With both Cr O as indigestible markers, were cold-pelleted (32 3 markers the recoveries measured with the PVTC mm die) and fed dry. This experiment was conducted
method for diet WB were significantly (P,0.001) at The Queen’s University of Belfast. After a 5-d
lower than for the other diets, values for TiO and2 adaptation period, faeces were collected for 7 d and
Cr O being, respectively, 31 and 24 units less than2 3 ileal digesta were collected for 12 h (08:00–20:00 h)
those for diet W. The ileal recovery of TiO for all of2 on the next two days.
the tested diets measured with the IRA method and In experiment 2, 30 German Landrace barrows,
for diets W, WR and WM measured with the PVTC approximately 15 kg, were subjected to an ileo-rectal
method were close to 100%, whereas recoveries of anastomosis by the procedure described by Hennig et
Cr O were 11 units lower (P2 3 ,0.001), for both the al. (1986). The experiment was conducted at
Ros-PVTC and IRA methods. tock. The six diets, based on W, WM and WB, of
As a consequence of the lower Cr O2 3 recovery, identical composition to those used in Belfast, were
the average values for IAD of DM, CP, energy and fed to five pigs per diet. Ileal digesta were collected
AAs in the four diets measured with TiO2 were for 5 d after a 7-d adaptation period. Samples of ileal
significantly higher than with Cr O (Table 2).2 3 digesta were pooled within period and pig for each
dietary treatment and freeze–dried. TiO was mea-2
sured according to Leone (1973). Cr O was mea-2 3 3.2. Ileal apparent digestibility of nutrients sured using the method of Saha and Gilbreath (1991) measured with markers (PVTC) and total by atomic absorption spectrophotometry. Further collection (PVTC and IRA) methods details of the diet compositions and methods of
analysis are given in a previous paper (Yin et al., As illustrated in Table 3, apart from CP
diges-2000). tibility (P,0.05), all diet3method interactions for
di-Table 1
Ileal recovery (%) of TiO and Cr O2 2 3
Diet W WR WM WB S.E.D. P Mean
a a a b
PVTC TiO2 99.9 94.9 95.5 67.8 4.92 ,0.001 89.7
a a a b
Cr O2 3 84.9 87.4 82.8 60.6 4.69 ,0.001 79.0
IRA TiO2 98.8 ND 101.1 95.2 2.70 NS 98.4
Cr O2 3 84.3 ND 88.7 86.8 2.39 NS 86.8
PVTC: Measured with PVTC total collection method. IRA: Measured with IRA method.
a,b
Values in the same row without a common superscript are significantly different (P,0.05). ND: Not determined.
Table 2 (TiO ) and IRA methods for W, WR and WM but the
2
Comparison of average values of ileal apparent digestibility of high fibre WB diet resulted in higher estimates of nutrients in diets W, WR, WM and WB measured with PVTC
apparent digestibility by the total collection method. cannula and either TiO or Cr O2 2 3
TiO2 Cr O2 3 S.E.D. P
DM 0.702 0.671 0.0095 ,0.001 4. Discussion
CP 0.772 0.748 0.0081 ,0.001
Energy 0.710 0.680 0.0084 ,0.001
4.1. Comparison of Cr O and TiO as markers2 3 2 Threonine 0.747 0.72 0.0092 ,0.001
for determination of ileal apparent digestibility of
Valine 0.748 0.722 0.0074 ,0.001
Cystine 0.785 0.760 0.0083 ,0.001 nutrients
Methionine 0.888 0.880 0.0039 ,0.05
Isoleucine 0.810 0.790 0.0042 ,0.001 Low faecal recoveries of Cr O and TiO (ranging 2 3 2
Leucine 0.820 0.801 0.0052 ,0.001
from 71 to 85%) in pigs have been often reported in Tyrosine 0.831 0.814 0.0048 ,0.001
the literature (Mueller, 1956; Moore, 1957, 1959; Phenylalanine 0.923 0.812 0.0199 ,0.001
Lysine 0.819 0.800 0.0054 ,0.001 Ishikawa, 1966; Ishikawa and Sugimura, 1973; Histidine 0.850 0.834 0.0055 ,0.001 Moughan et al., 1991; Greer, 1992; McClean, 1993; Arginine 0.883 0.870 0.0042 ,0.001 Yin et al., 2000). The present results show that the Aspartic acid 0.756 0.730 0.0091 ,0.001
ileal recoveries of TiO and Cr O are much higher2 2 3 Serine 0.812 0.792 0.0073 ,0.001
than those at the faecal level. For example, the ileal Glutamic acid 0.892 0.881 0.0036 ,0.001
Proline 0.787 0.763 0.0061 ,0.001 recoveries of TiO2 and Cr O2 3, measured with the Glycine 0.721 0.690 0.0086 ,0.001 IRA method, were 12.6 and 5.3 percentage units Alanine 0.719 0.688 0.0054 ,0.001 higher, respectively, than the overall (faecal) re-Total AAs 0.817 0.798 0.0061 ,0.001
Table 3
Comparison of ileal apparent digestibility of DM, CP, gross energy and selected AAs measured either with markers (TiO or Cr O ) using2 2 3
PVTC-cannula or by total collection (PVTC or IRA)
a
Diet TiO2 Cr O2 3 PVTC S.E.D. Diet3method IRA
DM W 0.773 0.741 0.772 0.763
WR 0.766 0.752 0.783 ND
WM 0.673 0.632 0.688 0.0155 P,0.001 0.624
WB 0.594 0.556 0.732 0.597
CP W 0.807 0.779 0.807 0.811
WR 0.804 0.790 0.808 ND
WM 0.757 0.727 0.769 0.0311 P,0.05 0.747
WB 0.720 0.693 0.808 0.745
Gross energy W 0.787 0.757 0.777 0.784
WR 0.771 0.759 0.792 ND
WM 0.683 0.644 0.698 0.0142 P,0.001 0.656
WB 0.596 0.558 0.724 0.601
Threonine W 0.77 0.737 0.768 0.764
WR 0.767 0.753 0.785 ND
WM 0.743 0.71 0.756 0.0128 P,0.001 0.732
WB 0.708 0.68 0.794 0.702
Valine W 0.766 0.733 0.764 0.805
WR 0.777 0.763 0.793 ND
WM 0.749 0.717 0.761 0.0123 P,0.001 0.769
WB 0.701 0.673 0.797 0.756
Isoleucine W 0.831 0.808 0.83 0.843
WR 0.837 0.826 0.848 ND
WM 0.803 0.778 0.813 0.0093 P,0.001 0.815
WB 0.768 0.746 0.841 0.8
Leucine W 0.849 0.827 0.849 0.851
WR 0.841 0.832 0.853 ND
WM 0.807 0.783 0.817 0.0121 P,0.001 0.82
WB 0.78 0.76 0.85 0.807
Phenylalanine W 0.935 0.83 0.85 0.876
WR 0.935 0.846 0.865 ND
WM 0.918 0.797 0.828 0.0068 P,0.001 0.851
WB 0.904 0.777 0.861 0.834
Lysine W 0.843 0.811 0.834 0.844
WR 0.832 0.822 0.845 ND
WM 0.82 0.797 0.829 0.0093 P,0.001 0.833
WB 0.786 0.767 0.855 0.807
Histidine W 0.865 0.845 0.864 0.869
WR 0.863 0.855 0.872 ND
WM 0.847 0.827 0.854 0.0075 P,0.001 0.865
Table 3. Continued
a
Diet TiO2 Cr O2 3 PVTC S.E.D. Diet3method IRA
Tyrosine W 0.849 0.828 0.849 0.851
WR 0.853 0.844 0.863 ND
WM 0.833 0.813 0.841 0.0082 P,0.001 0.858
WB 0.789 0.771 0.856 0.834
Arginine W 0.887 0.871 0.887 0.908
WR 0.882 0.875 0.89 ND
WM 0.886 0.871 0.89 0.0062 P,0.001 0.901
WB 0.876 0.865 0.917 0.895
Aspartic acid W 0.777 0.746 0.776 0.799
WR 0.779 0.765 0.796 ND
WM 0.751 0.72 0.764 0.012 P,0.001 0.769
WB 0.716 0.689 0.807 0.75
Serine W 0.834 0.81 0.833 0.836
WR 0.837 0.827 0.849 ND
WM 0.8 0.775 0.81 0.009 P,0.001 0.801
WB 0.779 0.757 0.85 0.786
Glutamic acids W 0.909 0.897 0.908 0.912
WR 0.908 0.902 0.915 ND
WM 0.879 0.863 0.885 0.0066 P,0.001 0.873
WB 0.873 0.861 0.913 0.879
Proline W 0.768 0.731 0.83 0.891
WR 0.881 0.874 0.732 ND
WM 0.763 0.733 0.763 0.0247 P,0.001 0.858
WB 0.709 0.683 0.77 0.854
Glycine W 0.749 0.712 0.745 0.784
WR 0.742 0.726 0.761 ND
WM 0.717 0.679 0.73 0.0157 P,0.001 0.74
WB 0.675 0.644 0.782 0.732
Alanine W 0.737 0.7 0.735 0.77
WR 0.75 0.734 0.769 ND
WM 0.719 0.683 0.732 0.0144 P,0.001 0.741
WB 0.666 0.635 0.773 0.714
Total AAs W 0.833 0.81 0.832 0.856
WR 0.851 0.846 0.856 ND
WM 0.808 0.784 0.817 0.0091 P,0.001 0.825
WB 0.783 0.764 0.854 0.814
a
IRA not included in statistical analysis, since the experimental design was different from the PVTC experiment. ND: Not determined.
energy and total AA measured with Cr O2 3 were Cr O2 3, TiO2 is insoluble in water, HCl, HNO3 or respectively 4.6, 3.2, 4.4 and 2.4% lower than those dilute H SO (Merck Index, 1989) and analysis of2 4 measured with TiO (Table 2). Jagger et al. (1992)2 TiO2 is a relatively simple and straightforward found that the ileal digestibilities of N and AAs procedure. High recoveries (95–100%) in samples of measured with Cr O2 3 were significantly lower (N, feeds and excreta of poultry and pigs have been 6.7% and the average value of 11 AAs, 6.1%) than reported (Njaa, 1961; Leone, 1973; Peddie et al., those measured with TiO , when both markers were2 1982; Jagger et al., 1992).
added to a barley and wheat based diet fed to
growing and finishing pigs. Furthermore, the results 4.2. Comparison of methods for measurement of of Jagger et al. (1992) and of this experiment show ileal apparent digestibility of nutrients
that the standard errors associated with apparent ileal
digestibility values calculated using each marker The excellent marker recoveries with TiO for the2 were lower with TiO2 than with Cr O2 3. This is W, WR and WM with the PVTC method and for the somewhat surprising in that the level of incorpora- W, WM and WB diets with the IRA method indicate tion of Cr O was higher than for TiO2 3 2.At these low that, under these conditions, digesta collection was levels it would be possible for problems to arise due fully representative of the material reaching the to lack of homogeneity of mixing. However, the low terminal ileum. This would be expected with the IRA standard errors obtained with TiO2 would suggest method where a complete 5-d collection was made that diet mixing was not a problem. but it is noteworthy that similar results occurred with The primary reason for the low recovery and the much shorter period of collection (24 h) using the variable results from Cr O2 3 may be related to PVTC technique. However, the result for the high-analytical problems arising mainly from interference fibre diet WB using the PVTC technique demon-by other minerals present in the sample (Williams et strates that quantitative collection of digesta was not al., 1962; Saha and Gilbreath, 1991). For example, achieved. This result therefore supports the reports of
¨
Williams et al. (1962) found a 12% decrease in Cr Kohler et al. (1991) and van Leeuwen et al. (1991) recovery when phosphate (PO ) was added to the4 of variable recovery with the PVTC technique solution of Cr. Saha and Gilbreath (1991) also dependant on diet composition and confirms the showed significant effects on recovery when varying necessity of using an appropriate indigestible marker. the concentration of Ca, P or Mg in diets and faeces Although a direct statistical comparison of the of pigs. These minerals occur in high concentrations PVTC and IRA techniques is not valid due to the in the digesta or faeces of pigs. This possibility is separate locations in which the techniques were used presently under investigation in our laboratory. In an and the different sources of pigs, the results given in initial study, three levels of Cr O corresponding to2 3 Table 3 for PVTC (TiO ) and IRA show close2 5, 10, 20 ppm were added to the faeces of pigs which numerical agreement. This, taken with the excellent had not received Cr O in the diet. The recoveries2 3 marker recoveries (Table 1), suggests that both were 88.0, 87.7, 83.3%, respectively. This is similar methods were giving reliable estimates of ileal to the mean recovery values reported by Saha and digestibility. Furthermore, the good agreement be-Gilbreath (1991) and the mean ileal recovery of tween IRA and PVTC (TiO ) for diet WB, where2 Cr O measured in this study.2 3 PVTC collection was not quantitative, suggests that In addition, although Cr O is insoluble in water,2 3 the digesta recovered was similar in composition to it is slightly soluble in acids and alkalis (Merck that by-passing the cannula.
post-beans in diets for growing pigs. M.Sc. Thesis. The Queen’s operative animal care. (2) Longer time for recovery
University of Belfast, Belfast. from the surgery. (3) Need for greater care to
¨
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Kreienbring, F., 1992. Methodenverleich zur Bestimmung der the IRA method, the surgery for the PVTC cannula- PrSzSkalen NShrstoffverdaulichkeit und AminosSureresorptionˇ ˇ ˇ ˇ tion is much easier to perform and less severe on the zwischen Schweinen mit ileorectal-anastomose und ileozSkal-ˇ
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Bruckenkanule. Arch. Anim. Nutr. 42, 197–211. animals than the IRA procedure and the PVTC
Ishikawa, S., 1966. Reliability of polyethyleneglycol as an in-cannulation technique causes less discomfort to the
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Agric. Biol. Chem. 37, 203–206. method is a better method for measuring ileal
Jagger, S., Wiseman, J., Cole, D.J.A., Craigon, J., 1992. Evalua-digestibility in most situations. It would, however, be tion of inert markers for the determination of ileal and faecal of considerable interest to make a direct comparison digestibility values in the pig. Br. J. Nutr. 68, 729–739. of the PVTC and SICV techniques. Kidder, D.E., Manners, M.J., 1978. Digestion in the Pig, Kingston
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