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Amino acid (AA) requirements for sows during pregnancy are currently under review. Moreover, requirement recommendations must be accompanied by an estimate of the bioavailability of AA from feeds to ensure adequate supply of AA and to minimize excess nitrogen excretion. Current ileal AA digestibility estimates are based on growing pig data; however, availability of AA in adult pigs may be different from that in growing pigs.
The metabolic availability (MA) of threonine (Thr) in corn and barley was determined in 6 pregnant sows using the indicator AA oxidation method and L-[1-13C] phenylalanine as the tracer AA. Sows were fed reference diets formulated from 30 to 75% of the AA breakpoint derived in Expt. 1; all other nutrients were set at 120% of requirement. Test ingredients diets were formulated to supply Thr at 75% of the determined requirement. Tracer phenylalanine was given orally in 8 one-half–hourly meals and expired 13CO2 was quantified. The determined MA of Thr from corn and barley fed to pregnant sows was 88.0 and 89.3%, respectively.
The determined MA was 7 and 9% greater than the published standard ileal digestibility estimates of Thr in corn (82%) and barley (81%), respectively. Mature animals have a greater capacity to digest and absorb nutrients from feed ingredients than previously assumed based on ileal digestibility studies. Sow diets formulated based on published ileal digestibility estimates are over-formulated with respect to available protein and AA and thus increase excess nitrogen excretion and potential environmental concerns. Although the current results are in relation to Thr availability, similar research would suggest an ~10% increase in AA and protein digestibility from common ingredients in adult sows.
In practical pig nutrition, where sow feed represents 20% of the total feed cost, a 10% increase in AA and protein availability can provide substantial savings in feed costs.
The metabolic availability (MA) of threonine (Thr) in corn and barley was determined in 6 pregnant sows using the indicator AA oxidation method and L-[1-13C] phenylalanine as the tracer AA. Sows were fed reference diets formulated from 30 to 75% of the AA breakpoint derived in Expt. 1; all other nutrients were set at 120% of requirement. Test ingredients diets were formulated to supply Thr at 75% of the determined requirement. Tracer phenylalanine was given orally in 8 one-half–hourly meals and expired 13CO2 was quantified. The determined MA of Thr from corn and barley fed to pregnant sows was 88.0 and 89.3%, respectively.
The determined MA was 7 and 9% greater than the published standard ileal digestibility estimates of Thr in corn (82%) and barley (81%), respectively. Mature animals have a greater capacity to digest and absorb nutrients from feed ingredients than previously assumed based on ileal digestibility studies. Sow diets formulated based on published ileal digestibility estimates are over-formulated with respect to available protein and AA and thus increase excess nitrogen excretion and potential environmental concerns. Although the current results are in relation to Thr availability, similar research would suggest an ~10% increase in AA and protein digestibility from common ingredients in adult sows.
In practical pig nutrition, where sow feed represents 20% of the total feed cost, a 10% increase in AA and protein availability can provide substantial savings in feed costs.
CL Levesque, S Moehn, PB Pencharz and RO Ball, 2011. The Journal of Nutrition, 141(3): 406-410.
