A total of 282 nursery pigs (PIC TR4 × 1050, initially 16.1 lb, 3 d postweaning) were
used in a 28-d growth trial to evaluate the effects of replacing fish meal with crystalline
amino acids on growth performance. Pigs were allotted to 1 of 6 dietary treatments
with 7 replications per treatment. There were 5 replications with 7 pigs per pen and 2
replications with 6 pigs per pen. Pigs and feeders were weighed on d 0, 7, 14, 21, and 28
to calculate ADG, ADFI, and F/G. A 2-phase diet series was used, with treatment diets
fed from d 0 to 14 and a common diet fed from d 14 to 28. All diets were in meal form.
For the 6 dietary treatments, the fish meal was included at: 4.50, 3.60, 2.70, 1.80, 0.90,
and 0.00% respectively. Crystalline lysine, methionine, threonine, tryptophan, isoleucine,
and valine all increased as fish meal decreased to maintain minimum amino acid
ratios. Also, increasing amounts of glutamine and glycine were used in diets containing
3.60% to 0.00% fish meal to maintain a lysine-to-CP ratio. From d 0 to 14, there
was no difference (P > 0.29) in ADG, ADFI, or F/G as the level of fish meal decreased
and crystalline amino acids increased. From d 14 to 28 (common diet period), no clear
effects (P > 0.09) on growth performance were detected. Overall (d 0 to 28), there was
no difference (P > 0.16) in ADG or ADFI. For F/G, a quadratic effect (P < 0.04) was
detected, which was the result of small improvements in F/G at the intermediate fish
meal levels (2.70 and 1.80). In conclusion, these data suggest that crystalline amino
acids, when balanced for minimum amino acid ratios, can be used to replace fish meal in
diets for 15- to 25-lb pigs.
