Abstract
Effects of Dietary Amino Acid Content Between 20 and 50 kg and
50 and 100 kg Live Weight on the Subsequent and Overall Performance
of Pigs.
Lee I. Chiba
Background Information & Objective
Many investigators have demonstrated that young pigs respond
to higher levels of amino acid than those currently recommended
by the NRC. However, the effect of growth during the early phase
of development on the subsequent performance is not well established.
Compensatory growth responses after a period of feed or protein
restriction in young pigs have been reported, indicating that
the young pig's nutritional status may have little importance
in terms of overall rate and efficiency of growth. In addition,
it is possible that the extent of compensatory growth may be
dependent on nutrient contents of diets offered during the latter
phase of growth. The research described herein was designed to
investigate the effects of dietary amino acid contents during
the grower and finisher phases on subsequent and overall growth
performance, carcass quality and internal organ weights of pigs.
Experimental Procedures, Results & Conclusion
Twenty-four gilts and 24 castrated males
averaging 18.5 kg were randomly assigned within sex to two grower
diets containing 1.77 (80% of the 1988 NRC requirement) or 3.20
g lysine/Mcal DE (adequate). When pigs weighed approximately
50 kg, 24 pigs (six gilts and six castrated males/diet) were
randomly selected for slaughter to assess carcass traits. The
remaining pigs were randomly assigned within the grower diet
and sex to two finisher diets containing 1.77 (NRC requirement)
or 2.56 g lysine/Mcal DE (80% of the grower diet containing 3.20
g lysine/Mcal DE) in a 2 x 2 factorial arrangement of treatments.
To maintain constant proportions among amino acids, a mixture
of 66.3% corn and 33.7% soybean meal was used as the basis for
all diets. The different amino acid concentrations but constant
DE content (3.50 Mcal DE/kg) were achieved by adjusting the proportions
of a corn-soybean meal mixture, dried fat, corn starch, sand
and powdered cellulose. Pigs were housed and fed in individual
pens. At approximately 100 kg, all pigs were slaughtered. Between
20 and 50 kg, pigs fed the high-amino acid diet grew 18% faster
(P < .001), and were 23 to 24% more efficient (P < .001)
in utilization of feed and energy than those fed the low-amino
acid diet. During 50 to 100 kg, however, pigs previously fed
the low-amino acid diet tended to gain more rapidly and efficiently
(P = .09) than those fed the high-amino acid diet, and there
were no differences in the performance of the two groups between
20 and 100 kg. Similarly, pigs fed the high-amino acid diet to
50 kg tended to have better carcass characteristics and heavier
(P < .001) liver and kidneys at 50 kg. However, the diets offered
between 20 and 50 kg had no effect on these criteria at 100 kg.
Between 20 and 100 kg, pigs fed the high-amino acid diet during
50 to 100 kg tended to gain faster (P = .08), and were more efficient
(P < .01) in utilization of feed and energy than those offered
the low-amino acid diet. The results indicated that the design of diets to maximize growth performance
of pigs between 20 and 50 kg may have little importance in terms of overall
productivity and efficiency. That is, pigs can be fed the diet containing marginally
deficient level of lysine during the grower phase without adversely affecting
the overall performance or carcass quality.
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