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Sixty-four Large White x Landrace primiparous sows were utilized to evaluate the influence of feeding 6 vs 9 Mcal ME/d during gestation on reproductive performance. The sows remained on their respective gestation diets for four parities if they successfully farrowed, rebred and conceived. Sows fed 9 Mcal ME/d gained more weight (P less than .05) through the gestation period during parities 1 and 2 and were heavier (P less than .01) on d 110 of gestation for combined parities. Lactation weight loss was greater (P less than .05) for the sows fed 9 Mcal ME/d, resulting in similar weights at weaning. Ultrasonic backfat measurements were greater (P less than .01) on d 110 of gestation for sows fed 9 Mcal ME/d during parity 1 and remained higher (P less than .01) through the fourth-parity gestation. Although sow weaning weights were similar, sows receiving 6 Mcal ME/d scanned less backfat thickness. Gestation treatment significantly affected consumption of a common lactation diet provided ad libitum. Sows fed 6 Mcal ME/d during gestation consumed an average of 22 kg more feed (P less than .01) during lactation than those sows receiving 9 Mcal ME/d. Litter performance as measured by number and weights of pigs born alive and weaned was not altered (P greater than .10) by gestation energy intake. Days to return to estrus and the number of sows remaining in the study for four parities were similar (P greater than .10) between the two treatment groups. The number of farrowings for the four parities totaled 164, with 83 and 81 farrowings for the sows fed 6 and 9 Mcal ME/d, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Four trials involving 426 crossbred pigs were conducted to determine the effect of protein restriction during early growth on subsequent performance and carcass characteristics at 100 kg. The experimental animals averaged 25 to 27 kg initial weight in trials 1, 2 and 3, and 18.2, 22.7 and 27.3 kg in three weight groups in trial 4. Pigs were fed corn-soybean meal supplemented diets of 12, 14 or 16% protein. Protein restriction (12 or 14% protein diets), to 52 kg in trial 1 and during the initial 4-wk period in trials 2, 3 and 4, reduced rate and efficiency of growth; performance was reduced more on 12% protein diets. In the subsequent growth period, early protein restriction improved gain and feed to gain ratio. Performance for the total period was similar for pigs fed a 14% protein diet continuously to that of pigs fed a 16 to 14% protein sequence when pigs had an initial weight of 25 kg or more. However, lighter weight pigs did not completely compensate for decreased performance during the early 4-wk period. Carcass characteristics were similar for all protein sequences.

Four 28-d trials were conducted using a total of 432 pigs, with average initial weight across trials ranging from 6.3 to 9.7 kg, to estimate the tryptophan (trials 1 and 2) and threonine (trials 3 and 4) requirements of pigs fed low protein, corn-sunflower meal diets. The effect of tryptophan, threonine and protein level on serum calcium, phosphorus and zinc also was studied. The diets contained either 12 or 13% protein and were calculated to be adequate in all nutrients except crude protein and the amino acid being investigated. A lysine supplemented, 18% protein, corn-sunflower meal diet was included in all trials as a positive control. In trial 1, weight gains of pigs increased linearly (P less than .005) while feed conversion improved cubically (P less than .05) as dietary tryptophan increased from .14 to .22%. Pigs fed the 18% protein diet gained faster (P less than .05) and required less feed/gain than pigs fed low protein diets. In trial 2, weight gains improved quadratically (P less than .005) and feed conversion improved linearly (P less than .05) as dietary tryptophan increased from .104 to .204%. Serum phosphorus and zinc concentrations were lower (P less than .05) in pigs fed the 18% protein diet. In both trials, serum urea N responded quadratically (P less than .05) to increasing dietary tryptophan, and was lower (P less than .05) in pigs that were fed diets supplemented with L-tryptophan than in those fed the low protein basal or 18% protein diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Two experiments were conducted to determine the effect of varying dietary selenium (Se) levels and Se source on growing swine. In Exp. 1, seleniferous wheat and oats were used to formulate diets containing .47, 2.58, 5.60 or 8.40 micrograms/g organic Se. Dietary Se level had no effect on pig performance during the 6-wk experiment as measured by daily gain, daily feed intake or feed/gain. Blood composition and enzyme activity were not affected by dietary treatment. Selenium concentrations of blood, hair, liver, kidney, heart, spleen and diaphragm muscle were increased linearly (P less than .01) as dietary Se increased. In addition, liver weight as a percentage of body weight was increased linearly (P less than .01) as dietary Se level increased. No signs of chronic Se poisoning were observed. Dietary treatments in Exp. 2 were similar to Exp. 1 with the exception that sodium selenite was utilized as the Se source and the diets were fed for 17 wk. Inorganic Se levels of .54, 2.63, 5.69 or 8.33 micrograms/g had no effect on pig performance as measured by daily gain, daily feed intake or feed/gain. Selenium concentrations of blood, hair, liver, kidney, spleen and diaphragm muscle were significantly increased as dietary Se level increased. Liver weight as a percentage of body weight was increased at the two highest dietary Se levels. Blood glutathione peroxidase activity was significantly increased by dietary treatment, while other blood variables were not affected. No signs of chronic Se poisoning were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

One hundred seventy-six crossbred weaned pigs (4 to 5 wk old) were used in two growth trials to determine the effect of excess arginine on pig growth and plasma amino acid levels. In the first 28-d growth trial, two lysine levels (1.03 and 1.26%) and three arginine levels (.94, 1.29 and 1.63%) were used in a nested treatment arrangement. Lysine supplementation improved daily gains (P less than .05), tended to improve feed efficiency (P less than .12) and caused a general reduction in plasma essential amino acid levels. Arginine had no effect on daily gain or feed intake, but pigs fed 1.03% lysine and 1.63% arginine had reduced gain/feed (P less than .05). Arginine did not affect gain/feed of pigs fed 1.26% lysine. Plasma lysine levels were reduced (P less than .06) by excess arginine in pigs fed 1.26% lysine, but not in pigs fed 1.03% lysine. The four treatments for the second 26-d growth trial consisted of three diets containing .92% lysine and either .72, 1.10 or 1.61% arginine and a positive lysine control (1.10% lysine, .72% arginine). Lysine was the limiting amino acid in the basal diet, but arginine had no effect on daily gain, daily feed intake, gain/feed or plasma lysine levels. Plasma threonine and methionine levels were reduced by excess arginine in both experiments, while the other plasma essential amino acid levels were not affected by dietary arginine. Conclusions are that large excesses of added arginine may affect lysine utilization, but pig performance was affected only when excess arginine was combined with a lysine deficiency. The arginine levels similar to those found in grain-soybean meal swine diets had no effect on pig performance in these experiments.

A total of 96 crossbred pigs received various levels of sodium selenite to determine the effect of dietary selenium (Se) on growing swine fed corn-soybean meal diets. Levels of supplemental Se were 0, 4, 8, 12, 16 and 20 micrograms/g. There were linear decreases (P less than .01) in both gain and feed intake with increasing levels of dietary Se. Feed/gain increased numerically as dietary Se increased. Hair Se increased quadratically (P less than .01) and blood Se increased linearly (P less than .01) with increasing level of dietary Se. Cell volume and hemoglobin were not affected by dietary treatment. Increasing dietary Se significantly increased glutathione peroxidase (GSH-Px), glutamic-oxalacetic transaminase (GOT). and glutamic-pyruvic transaminase (GPT). External signs of selenosis were noted in some pigs fed 12 or 20 micrograms/g of Se. The toxic level of Se in a corn-soybean meal diet for crossbred pigs appears to be between 4 and 8 micrograms/g. Of variables studied, growth rate was the most sensitive indicator of chronic selenosis in swine.