In an attempt to map the gene (or genes) controlling the synthesis fo the fourth component of complement (C4), we performed linkage studies in a family with hereditary C4 deficiency. The proband, a seven-year-old boy with lupus erythematosus, consistently lacked deteftable serum C4 by both functional and protein measurements. The complement defect was transmitted as an autosomal recessive disorder. Eight of 15 family members were considered to be heterozygotes, seven because of low C4 levels and one because of genetic data (obligate heterozygote). The gene (or genes) coding for C4 deficiency appeared to be linked to the major histocompatibility complex (A2,B12,DW2 on the maternal side and A2,BW15,LD108 on the paternal side) and to other markers known to be in close proximity to the histocompatibility complex on chromosome 6 (phosphoglucomutase-3, glyoxalase-1 and properdin factor B).

Growth trials with starter (n = 120, 6.8 kg initially, 28 d of age, Exp. 1) and finisher (n = 70, 59 kg initially, Exp. 2) pigs were conducted to compare quality protein maize (QPM, .40% lysine) and normal corn (.31% lysine) in simple corn-based diets containing the same levels of soybean meal. In Exp. 1, pig performance was similar (P greater than .10) on all diets, regardless of the level of soybean meal, suggesting that QPM and normal corn have similar feeding value in lysine-adequate (.99 to 1.11%) diets. In Exp. 2, less soybean meal was needed in QPM than in normal corn diets to maximize performance; increasing soybean meal from 10.8 to 13.8% improved rate (P less than .05) and efficiency (P less than .01) of gain of pigs fed normal corn diets but had no effect on performance of pigs fed QPM diets. A QPM-based diet containing 6% soybean meal and supplemental lysine and tryptophan failed to maximize feed efficiency, but growth rate was equal to that obtained on the normal corn diet with 13.8% soybean meal. The apparent fecal digestibility of GE and ileal digestibility of N were similar for QPM and normal corn, but apparent ileal digestibility of most essential amino acids was slightly higher for QPM (Exp. 3). Experiment 4 compared apparent digestibilities of QPM, conventional opaque-2 corn and two high-protein corns. Digestibilities differed (P less than .05) among the corns, but the absolute differences were small and were likely due to differences in amino acid content of the corns.(ABSTRACT TRUNCATED AT 250 WORDS)

An experiment was conducted to evaluate the interactive effects among porcine somatotropin (pST), salbutamol, and dietary lysine on growth performance, nitrogen balance, and carcass characteristics of finishing barrows (n = 32; 62.8 kg initially). Two replicate 32-d studies were set up in a split-plot design to evaluate singular and combined use of pST (0 or 4 mg/d) and salbutamol (0 or 2.75 ppm of the diet) as whole-plot treatments and diets containing .8, 1.2, 1.6, or 2.0% lysine as subplot treatments. Dietary lysine levels were administered within subplots in a 4 x 4 Latin square with pigs allowed 4 d of adjustment to diets followed by 4 d of urine and feces collection for determination of N retention and apparent digestibility of DM and N. Interactions between lysine and salbutamol were not found (P > .16). A pST x lysine interaction (P < .05) resulted in ADG being maximized at 1.2% lysine for pST-treated pigs (lysine quadratic, P < .02) but decreased linearly (P < .02) with increasing lysine for pigs receiving buffer. Pigs injected with 4 mg/d of pST had improved gain:feed (G:F) up to 1.2% lysine (lysine quadratic, P < .05), but no further increase to 2% lysine, whereas pigs injected with buffer showed no benefit from increased lysine (pST x lysine, P < .06). Pigs receiving buffer had greater increases in plasma urea N (PUN) as lysine increased than those receiving pST (pST x lysine, P < .002), but PUN was reduced by pST (P < .001) regardless of lysine level.(ABSTRACT TRUNCATED AT 250 WORDS)

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