The
objective of the experiments conducted for this dissertation was to determine
the standardized ileal digestibility (SID) of amino acids (AA) in a variety of
feed ingredients for broiler chickens and pigs. The effects of casein in
experimental diets on the SID of AA in corn distillers’ dried grains with
solubles (DDGS) fed to pigs were evaluated. The SID of AA in feed ingredients,
which include full-fat soybean (FFSB), two soybean meals (SBM), peanut flour
(PNF), full-fat canola seeds (FFCS), canola meal (CM), canola expellers (CE),
hydrolyzed feather meal (HFM), flash dried poultry protein (FDPP), poultry meal
(PM), and meat and bone meal (MBM), were compared in broiler chickens and pigs.
One of the studies determined the ileal digestibility of AA in casein by
regression analysis and investigated the effects of 60 g/kg casein in
experimental diets on the SID of AA in DDGS. The ileal digestibility of AA in
casein were close to 100%, ranging from 95.5% (SE = 9.10) for Cys to 103.1% (SE
= 4.40) for Arg. In addition, the SID of Lys and Phe in DDGS determined by pigs
fed the diet containing DDGS and casein were greater (P < 0.05) than the values determined by pigs fed the diet
containing DDGS without casein. Based on the results of this experiment, two
additional experiments were conducted to determine the effects of graded
concentrations of casein from 55 to 165 g/kg in experimental diets on the SID
of AA in DDGS and to determine the effects of dietary DDGS concentrations
(i.e., 155.6 or 466.8 g/kg) and addition of casein in experimental diets on the
SID of AA in DDGS. The SID of indispensable AA, except for Arg and Lys,
linearly decreased (P < 0.05) as
the concentration of casein in experimental diets increased. Moreover, pigs fed
the diets containing 155.6 g/kg DDGS had less (P < 0.05) SID of indispensable AA, except for Trp, in DDGS than
those fed the diets containing 466.8 g/kg DDGS regardless of the addition of
casein in experimental diets. Therefore, it may be concluded that the addition
of casein improves the SID of AA in DDGS, but reduced DDGS concentration in
experimental diets decreases the SID of AA in DDGS. In one pair of experiments
conducted to compare the SID of AA in FFSB, SBM containing 430 g/kg crude
protein, SBM containing 470 g/kg crude protein, and PNF between broiler
chickens and pigs, the SID of AA, except for Trp, Ala, and Glu, in test
ingredients for pigs were greater (P
< 0.05) than the values for broiler chickens. In addition, in both broiler
chickens and pigs, the SID of Ile, Leu, and Val in FFSB were less (P < 0.05) than in the other test
ingredients. In another pair of experiments conducted to compare the SID of AA
in FFCS, CM, and CE between broiler chickens and pigs, interactions (P < 0.05) between experimental diets
and species were observed in the SID of AA, except for Lys, Gly, Pro, and Ser.
The SID of AA in FFCS for broiler chickens were greater (P < 0.05) than pigs; however, there was no difference in the SID
of AA in CM or CE between broiler chickens and pigs. The objective of a third
pair of experiments was to compare the SID of AA in HFM, FDPP, PM, and MBM fed
to broiler chickens and pigs. There were interactions (P < 0.05) between experimental diets and species in the SID of
His, Thr, Trp, and Val. In broiler chickens, the SID of His, Thr, and Trp in
FDPP and PM were greater (P <
0.05) than in HFM but were less (P
< 0.05) than MBM; however, difference in SID of His, Thr, and Trp among
FDPP, PM, and MBM was not observed in pigs. Based on the results of three pairs
of studies, it was revealed that differences in SID of AA in common feed
ingredients for both broiler chickens and pigs were affected by species.
Therefore, it may be concluded that the effects of feed ingredient-specific
factors on the SID of AA are different between broiler chickens and pigs.