Y. Buyukates et al., Phosphorus fractions of various feedstuffs and apparent phosphorus availability to channel catfish, N AM J AQUA, 62(3), 2000, pp. 184-188
This study was conducted to determine different phosphorus fractions in cor
n, cottonseed meal, dehulled soybean meal, fish meal analog, meat-bone meal
, fish meal from menhaden Brevoortia spp., rice bran, sorghum, wheat, and w
heat middlings, and phosphorus availability of these feedstuffs to channel
catfish Ictalurus punctatus. Test diets consisting of a 70:30 mixture of re
ference diet to test ingredient were used with chromic oxide as the nondige
stible marker. The various test diets were fed for 5 d in triplicate to gro
ups of channel catfish weighing approximately 150-200 g, and the fecal samp
les were obtained by stripping approximately 12 h after feeding. Feed and f
ecal samples were analyzed for total phosphorus (TP) and soluble reactive p
hosphorus (SRP), from which apparent availability coefficients were calcula
ted. Apparent availability of SRP exceeded 92% for all ingredients, except
menhaden fish meal (61%) and wheat (44%). Total phosphorus availability fro
m animal products was variable: 47% for menhaden fish meal, 54% for meat-bo
ne meal, and 92% for fish meal analog. Plant products also had variable TP
availability values: 33% for corn, 35% for both sorghum and soybean meal, 5
1% for rice bran, 66% for cottonseed meal, 77% for wheat middlings, and 83%
for wheat. These phosphorus availability values obtained for the various f
eedstuffs may allow formulation of diets that are better utilized by channe
l catfish and reduce phosphorus excretion.