Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

C. Ross Hamilton


Experiments were conducted to investigate effects of dietary lysine (L YS) level on the performance of nursery pigs fed diets containing corn gluten meal (CGM) and effects of dietary tryptophan (TRP) level on serotonin (5-Hl) synthesis along with growth hormone (GH) release in finishing gilts. All experimental designs consisted of three complete blocks with a factorial treatment arrangement. In experiment (EXP) 1, the basal diet contained corn, CGM and soybean meal (SBM) and was formulated for .14% TRP and .50% LYS. Synthetic L-LYS-HCL was added to the basal diet to produce four dietary LYS levels. Also included were two corn-SBM diets formulated to contain .14% TRP and .50% LYS either with (+REF) or without (-REF) .45% added LYS. For the overall 21-d period, increasing dietary LYS had a quadratic effect (P=.01) on ADG, ADFI and gain/feed. Pigs fed the +REF diet had greater (P=.06) ADG, ADFI and gain/feed than pigs fed the CGM diet containing .95% LYS. Orts were lower (P=.02) for pigs fed the -REF diet than for those fed the CGM diet with .50% LYS. Plasma urea nitrogen (PUN) and plasma TRP concentrations decreased quadratically with increasing dietary LYS (P=.1). These data suggest a range between .65 and .80% dietary LYS to be adequate for 10-20 kg pigs fed high zein diets containing .14% TRP. Additional LYS supplied as L-LYS-HCL depressed ADFI, resulting in concomitant decreases in ADG and gain/feed. In EXP 2, gilts were fed a corn-SBM basal diet with 0 or .09% added L-TRP and weekly intraventricular administration of 0 (placebo) or 3 mg/kg BW of para-chlorophenylalanine (p-CPA), an inhibitor of 5-HT synthesis. The basal diet was formulated to contain 11% CP, .12% TRP and .45% LYS plus .15% added L-LYS. For the overall 28-d period, a dietary TRP x p-CPA interaction occurred (P=.03) for ADG and ADFI. Among gilts fed similar TRP levels, administration of p-CPA reduced ADG (769 vs 938 g) when 0% L-TRP was added to the diet and increased ADG (1000 vs 901 g) when .09% L-TRP was added. Similar results occurred for ADFI; administering p-CPA decreased ADFI (2.66 vs 3.07 kg) with 0% added L-TRP and increased ADFI (3.05 vs 2.60 kg) when .09% L-TRP was added. The administration of p-CPA caused a reduction (P=.05) in PUN concentrations when gilts were fed either 0% or .09% added L-TRP diets. Gain/feed increased (P=.01) as .09% L-TRP was added, but was not affected (P>.10) by p-CPA administration. GH concentration decreased (P=.07) over time from d 0 to d 28, but was unaffected by treatment (P>.10). Plasma 5-HT, brain TRP and brain neutral amino acid (NM) responded in a TRP X p-CPA interaction (P=.09), but brain 5-HT was unaffected by treatment (P>.1). The administration of p-CPA decreased plasma 5-HT when gilts were fed 0% L-TRP and increased plasma 5-HT when fed .09% added L-TRP. Similar results occurred for brain TRP; administering p-CPA reduced TRP in the brain with either diet fed containing 0% or .09% added L-TRP. Brain NM increased with the addition of .09% L-TRP to the diet, plus the administration of p-CPA increased brain NM concentrations when gilts were fed 0% added L-TRP. Inhibiting 5-HT synthesis depressed intake and gain when marginal TRP levels were fed but not when dietary TRP was in excess. A relationship exists between dietary TRP and 5-HT, but not GH in gilts fed TRP levels of .12 or .21 %. In EXP 3, five treatments were produced by adding synthetic TRP to a gelatin based corn-SBM diet. During the 28-d period, a linear increase (P=.07} for ADFI and a linear decrease (P=.01) for orts were observed by pigs fed added levels of TRP. ADG and gain/feed were unaffected (P>.1) by TRP additions. Increasing TRP resulted in a linear decrease for PUN (P=.006) and a linear increase in total plasma TRP (P=.001). Feeding dietary TRP levels ranging did not induce GH release in the gilt. This study indicates .20% dietary TRP maybe adequate for finishing gilts fed .65% LYS.

Library of Congress Subject Headings

Swine -- Feeding and feeds
Amino acids in animal nutrition




South Dakota State University



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