Abstract
Effects of Nutritional History on the Subsequent and Overall
Growth Performance and Carcass Traits of Pigs.
Lee I. Chiba
Background Information & Objective It has been demonstrated over the years that growth performance
of starter pigs can be improved by feeding diets containing various
special ingredients. Similarly, many investigators have demonstrated
that grower pigs respond to higher levels of amino acid than
those currently recommended by the NRC. The effect of growth
responses during the starter and(or) grower phase on the subsequent
and overall performance of pigs is, however, not well established.
In addition, there is paucity of information on the effect of
amino acid levels in later life on the subsequent growth performance
and(or) carcass quality of pigs receiving different levels of
nutrient during the early stage of development. The research
described herein was designed to investigate the effects of nutritional
status during the starter phase and levels of dietary amino acid
during the grower and finisher phases on the subsequent and overall
growth performance and carcass traits of pigs.
Experimental Procedures, Results & Conclusions
Sixty-four crossbred pigs weaned at 25 +/-
3 days were randomly assigned to two starter dietary treatments
(simple, corn-soybean meal diet with marginal lysine content
or complex diet) with four pens per diet. After a 4-week starter
phase, three gilts and three castrated males from each pen were
selected and moved to the individual feeding pens. Pigs were
randomly assigned to two grower diets (1.77 or 3.20 g lysine/Mcal
DE) on the basis of the starter diet and sex. When pigs weighed
approximately 50 kg, pigs were randomly assigned within the grower
diet and sex to two finisher diets (1.77 or 2.56 g lysine/Mcal
DE) in a 2x2x2 factorial arrangement of treatments. The amino
acid balance of the three grower and finisher diets (3.50 Mcal
DE/kg) was maintained by using a fixed proportion of corn and
soybean meal. Average initial weights were 6.8, 22.4 and 50.5
kg for the starter, grower and finisher phases, respectively.
At an average weight of 107.6 kg, all pigs were slaughtered to
assess carcass traits. Pigs fed the complex starter diet grew
33% faster (P < .01) and
17% more efficiently (P < .05) than those fed the simple starter
diet. The starter diet, however, had no effect on weight gain
of pigs in the subsequent phases. During the grower phase, pigs
fed the high-amino acid diet grew faster (P = .09), and had lower
ultrasound backfat thickness (P < .001) than those offered the
low-amino acid diet. During the finisher phase, however, pigs
fed the low-amino acid diet during the grower phase grew faster
(P < .05) and more efficiently (P = .09) than those fed the high-amino
acid diet. Because of this turnaround, there was no difference
in the overall performance of pigs during the grower-finisher
phase. Similarly, the grower diet had no clear effects on final
carcass traits or the rate of lean accretion. The results indicate that formulating diets to promote optimum performance
of starter pigs can be justified because it will result in better overall growth
performance. In contrast, grower pigs can be offered diets that are marginally
deficient in amino acids without adversely affecting overall growth rate or
final carcass traits.
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