Five experiments involving 359 weanling (8 kg) pigs were conducted to evaluate the effects of dietary excesses of DL-methionine (Met), L-tryptophan (Trp), L-threonine (Thr) or L-leucine (Leu) when added to a 20% crude protein corn-soybean meal (C-SBM) diet. Experiments involved supplementing the basal diet with 0, .5, 1.0, 2.0 or 4.0% excesses of Met, Trp or Thr, or in the case of Leu, a 0, 1.0, 2.0, 4.0 or 6.0% excess. Levels of .5 and 1.0% excess Met did not depress feed intake (FI), weight gain (G) or gain/feed (G/F); 2.0 and 4.0% additions, however, depressed both FI and G but not G/F. Free Met in blood plasma increased linearly as dietary Met level increased, reaching over a 100-fold elevation at the highest Met level fed. Plasma Thr and serine (Ser) increased, and glycine (Gly) decreased, with each added increment of Met. With Trp, only the 4.0% addition depressed FI and G (but not G/F). None of the levels of excess Thr depressed performance. Excess Thr, in fact, tended to increase G/F. Free Thr, Ser and Gly in plasma increased linearly as graded increments of excess Thr were added to the diet. With Leu, a 6% addition depressed weight gain and food intake (but not G/F) but 1, 2 or 4% excesses were without effect. Plasma free Leu increased linearly while free isoleucine and valine decreased as graded increments of Leu were added to the diet. These results suggest that pigs can tolerate considerable excesses of Met, Trp, Thr and Leu without experiencing decreased voluntary feed intake or weight gain.(ABSTRACT TRUNCATED AT 250 WORDS)

Six experiments involving 706 newly weaned 28- to 32-d-old pigs were conducted to evaluate the efficacy of copper (Cu) sulfate (to provide 250 mg/kg Cu), antibiotic-sulfa combinations [chlortetracycline, 110 mg/kg + penicillin, 55 mg/kg + sulfamethazine, 110 mg/kg; i.e., Aureo-Sulfa-Penicillin (ASP) or tylosin, 110 mg/kg + sulfamethazine, 110 mg/kg; i.e., Tylosin-Sulfa (TS)] and anhydrous citric or fumaric acid (.75 to 1.5% of the diet). The basal experimental diet was a 19% crude protein (CP)-fortified corn-soybean meal diet (1.08% lysine) containing 7% dried whey and 3% fish meal. Marked and consistent gain and gain/feed responses occurred from the Cu supplement, particularly during the first week postweaning. The antibiotic-sulfa combinations were less efficacious than Cu during the 1-wk postweaning stress period. During either the 1- or 3-wk growth periods, ASP and TS showed additivity with Cu in promoting rate and efficiency of weight gain. Liver Cu was increased by Cu addition to the diet, but neither ASP nor TS affected Cu deposition in the liver. In a factorial experiment involving 17% (1.01% lysine) or 20% CP (1.23% lysine) corn-soybean meal diets containing either no dried whey or an addition of 25% whey, Cu supplementation elicited marked improvements in rate and efficiency of weight gain, particularly in diets without added whey. Likewise, whey addition improved pig performance, especially when added to the diets containing no supplemental Cu.(ABSTRACT TRUNCATED AT 250 WORDS)

Six experiments were conducted with 8-d-old crossbred chicks to evaluate the effects of 4% excesses of DL-methionine (Met), L-phenylalanine (Phe), L-tryptophan (Trp), L-lysine (Lys), L-histidine (His), L-threonine (Thr), L-isoleucine (Ile), L-arginine (Arg), L-valine (Val) or L-leucine (Leu) on growth or dietary "choice" (i.e., self-selection) when added to 23% protein corn-soybean meal (C-SBM) diets. Arginine and His were supplied as the free base and Lys as Lys X acetate to avoid acid-base problems. In the growth studies, weight gain was reduced 92, 79, 53, 50, 47, 31, 29, 15, 9, 4 and 0% by additions of 4% Met, Phe, Trp, His, Lys, Tyr, Thr, Ile, Arg, Val and Leu, respectively. Improvements (P less than .05) in weight gain, feed intake and gain/feed occurred by addition of 1% Arg to the C-SBM diet supplemented with 4% excess Phe or Tyr. Addition of 1% Arg to the C-SBM diet supplemented with 4% excesses of most of the other amino acids also tended to improve performance, although diets imbalanced with Lys, Val or Leu did not respond to supplemental Arg. Self-selection studies revealed that chicks preferred the C-SBM diet containing 4% excess Lys over diets containing 4% excesses of Met, Thr, Arg or Trp. Moreover, chicks preferred diets with 4% excess Met, Thr or Arg over those containing an equal excess of Trp. When given a choice between the C-SBM diet and this diet supplemented with 4% Leu, chicks consumed similar quantities of both diets.

We conducted two trials with growing-finishing pigs (Pig Improvement Company line 405 x Camborough 15) to evaluate the effects of space allocation on performance and CP requirements. In Trial 1, a 2 x 3 factorial (two levels of space, three CP regimens) was used with 252 pigs. Pigs were allocated to either .23, .28, .37, or .50 m2 per pig (crowded) or .37, .47, .60, or .74 m2 per pig (uncrowded) during the 18 to 36, 36 to 55, 55 to 91, and 91 to 127 kg weight periods, respectively. Diets contained 16.1, 18.6, or 21.1% (18 to 36 kg), 15.3, 17.8, or 20.3% (36 to 55 kg), 14.7, 17.2, or 19.7% (55 to 91 kg), and 12.8, 15.3, or 17.8% (91 to 127 kg) CP. The 16.1, 15.3, 14.7, and 12.8 % CP (control) diets contained 1.09, .86, .82, and .65% lysine, respectively. Crude protein levels (Trials 1 and 2) were achieved by substituting soybean meal for corn. In Trial 1, a CP x space interaction ( P < .03) for gain:feed suggested that feed efficiency of grower pigs was improved to a greater extent in uncrowded pigs than in crowded pigs. Grower pigs (18 to 55 kg) with less space had depressed (P < .05) feed intake and gain and a lower (P < .10) feed efficiency than uncrowded pigs. Added CP improved (P < .05) rate and efficiency of gain in grower pigs. Overall (18 to 127 kg), crowded pigs had reductions (P < .05) in gain (17.6%), feed intake (11.3%), and gain:feed ratio (7.1%) compared to uncrowded pigs. Trial 2 involved 216 finishing pigs in a 2 x 2 factorial (two levels of space, two CP regimens). Pigs were provided with either .37 or .50 m2 per pig (crowded) and .60 or .74 m2 per pig (uncrowded) during the 55 to 91 and 91 to 127 kg weight periods, respectively. The diets contained 14.1 or 17.1% CP (55 to 91 kg) and 12.1 or 15.1% CP (91 to 127 kg). Lysine levels were .67 and .53% for the 14.1 and 12.1% CP diets, respectively. Overall (55 to 127 kg), crowded pigs had depressed (P < .05) gains (15.4%), feed intakes (9.5%), and feed efficiencies (6.8%) compared with uncrowded pigs. Increasing CP resulted in improved (P < .05) ADG (7.4%) and gain:feed (8.3%) in crowded and uncrowded pigs. The data suggest that pigs with lower feed intakes as a result of space restrictions do not have higher CP requirements than those with more space.

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