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The objective of this study was to determine whether the improvements in growth and efficiency of gain achieved by recombinant porcine somatotropin (pST) are associated with altered expression of the p94, calpastatin, or α-actin genes in porcine longissimus (LD) muscle. Forty-eight barrows (initial 64.2 to 67.4 kg BW) were assigned to four treatments (n = 12) arranged as a 2 × 2 factorial in a randomized complete block design. Factors were duration of treatment (3 or 6 wk) and pST administration (0 or 3 mg·pig−1·d−1). Plasma samples were obtained 24 h after the first pST injection and at the end of the each treatment period for assays of selected variables. The LD samples were obtained at 3 and 6 wk of pST treatment. Northern blot analysis of calpastatin expression in LD muscle revealed three distinct transcription products of approximately 8.5 (CPST I), 5.5 (CPST II), and 2.5 (CPST III) kb; CPST II was reduced (P< .02) 33 and 61% by pST at 3 and 6 wk, respectively, whereas CPST I and III were not influenced (P> .12). Neither α-actin nor p94 was responsive to pST injection. As expected, pST resulted in higher (50%, P< .02) plasma insulin within 24 h and one- and twofold higher (P< .01) concentrations at 3 and 6 wk, respectively. Glucose was increased (P< .01) at 3 (15%) and 6 (10%) wk, whereas urea nitrogen was reduced (32 to 36%, P< .01). The efficacy of pST was evident in that ADG was improved (P< .01) 11 to 13% independent of time. Likewise, feed intake was reduced (P< .01) 10 to 11% and gain: feed improved (P< .01) approximately 26% for pigs receiving pST independent of time. These data indicate that the enhanced muscle growth achieved by pST is not associated with altered expression of p94 or α-actin, or an increase in the abundance of any calpastatin transcription product.

Thirty-seven pigs were used to evaluate the effects of age and weaning on the level of protease in the gastric mucosa and trypsin, chymotrypsin, amylase and lipase in the pancreas. There was a positive allometry of the pancreas and gastric mucosa associated with age and with weaning to a solid diet. Increases with age in total activity of chymotrypsin. trypsin, amylase and gastric proteases were due to increases in both tissue weight and enzyme activity per gram of tissue. A general depression in pancreatic enzymatic activities, but not in gastric proteolytic activity, was found during the first week following weaning. Forty pigs were used in a second trial to evaluate the effects of age and weaning diet on the same digestive enzymes. Total activity of all enzymes assayed increased with time postweaning. Increases in total activity of lipase and chymotrypsin were due primarily to increased pancreatic weight postweaning. Amylase trypsin and gastric protease increases were due both to increased tissue weight and increased activity per gram of tissue. There were no effects of diet on the weight of gastric mucosa or the level of activity of the gastric proteases. Pigs fed a diet containing 20% whey had larger pancreases (P<.10) at slaughter and a greater, but nonsignificant, mean activity per gram of pancreas for all pancreatic enzymes. It appears that the pig has sufficient pancreatic and gastric enzyme activity so that performance should not be limited, with the possible exception of the period shortly after weaning. However diet digestibility and subsequent pig performance may be more directly related to the extent of release of these enzymes into the intestine and the conditions that exist therein.

Piglets were provided supplemental energy as oral doses of corn oil to find whether such treatment might improve survival or weight gains. A total of 1,840 piglets from 182 litters was used. Piglets were allotted to dosed and control treatments within litter on the basis of body weight. Dosed piglets received a total of 8 ml of corn oil in four doses during the first 48 h postpartum. The survival rate to weaning was high and not affected (P>.10) by the corn oil doses. Deaths of piglets low in birth weight were delayed by the fat doses, suggesting some utilization. The fat doses did not affect piglet weight gain. Factors affecting preweaning survival and growth of piglets were also evaluated using data from the same piglets. Specific factors investigated were sex, parity of dam, birth weight, litter size and the mean and standard deviation of piglet birth weights within litters. Male piglets were heavier at birth than females, but there was no sex effect on weight at 7 d or at weaning. Smalt males were less likely to survive to 3 d than were small females. Litters from primiparous sows were smaller at birth and weaning, but had lower percentages of stillbirths and of preweaning deaths than did those from multiparous sows. Piglets from primiparous sows were more uniform in birth weight. Piglets that were heavier at birth grew faster and were more likely to survive. Litter size affected growth but not survival of piglets. A heavier average birth weight in the litter reduced slighdy the growth rate of individual piglets. An increase in variability of piglet birth weight within a litter was associated with an increase of the percentages of stillbirths and of preweaning mortality. A few litters accounted for a major portion of the mortality. Much of the variation in piglet mortality and growth was not explained by factors considered.

A study was conducted to evaluate the use of deuterium oxide (D2O) for in vivo estimation of body composition of diverse types of pigs. Obese (Ob, 30) and contemporary Hampshire × Yorkshire (C, 30) types of pigs used in the study were managed and fed under typical management regimens. Indwelling catheters were placed in a jugular vein of 6 Ob and 6 C pigs at 4, 8, 12, 18 and 24 wk of age. The D2O was infused (.5 g/kg body weight) as a .9% NaCl solution into the jugular catheter. Blood samples were taken immediately before and at .25, 1, 4, 8, 12, 24 and 48 h after the D2O infusion and D2O concentration in blood water was determined. Pigs were subsequently killed by euthanasia injection. Contents of the gastrointestinal tract were removed and the empty body was then frozen and later ground and sampled for subsequent analyses. Ground body tissue samples were analyzed for water, fat, N, fat-free organic matter and ash. Pig type, age and the type × age interaction were significant sources of variation in live weight, D2O pool size and all empty body components, as well as all fat-free empty body components. Relationships between age and live weight or weight of empty body components, and between live weight, empty body weight, empty body water or D2O space and weight of empty components were highly significant but influenced, in most cases, by pig type. The results of this study suggested that, although relationships between D2O space and body component weights were highly significant, they were influenced by pig type and were little better than live weight for the estimation of body composition.

In a series of five trials, 680 crossbred pigs were fed isolysine diets in which high protein (13.8 to 16.0%) oats constituted 0, 20, 40 or 60% of the cereal portion. There was a linear depression in average daily gain (P<.001) and average daily feed intake (P<.005) with increasing level of oats, but feed/gain was unaffected (P>.05) during the growing period from 22 to 46 kg. There were no significant differences in average daily gain during the finishing period from 46 to 102 kg; however, feed/gain increased linearly (P<.01) with increasing level of oats in the diet. Increases in the percentage of oats in the cereal portion of the diet resulted in a linear (P<.01) decrease in average daily gain and an increase (P<.01) in feed/gain for the entire feeding period. We conclude that high protein-high lysine oats of the quality used in these trials can be included at up to 20% of the cereal portion of the diet without greatly affecting performance.

Sixty-four gilts, average initial weight of about 120 kg, were used to evaluate the use of Distillers Dried Grains with Solubles (DDGS) as a replacement for soybean meal in a corn:soybean meal diet fed during gestation. Dietary levels of DDGS were 0, 17.7 and 44.2%, with all diets containing about .42% (calculated) lysine. Two gilts from each treatment were used in a nitrogen balance determination during the 84th through the 88th day of gestation.Average gestation gain, litter size and weight at birth were similar for all dietary treatments. During lactation all sows received a fortified 16% crude protein diet. Litter size and weight at weaning (28 days) and sow weight change were similar for all groups.Grams of nitrogen retained per day, 84th through the 88th day of gestation, did not differ significantly among diets. Percent of dietary nitrogen retained was lower (P<.05) from the 17.7 and 44.2% DDGS diets than from the control diet, which likely reflects the deamination of excess amino acids in the DDGS diets.These results show that DDGS can replace soybean meal on a lysine-equivalent basis as a source of supplemental amino acids in diets for gestating swine.

A dynamic, partially stochastic mathematical model describing the reproductive performance of a sow herd is presented. The model simulates a herd that averages 17.27 sow days/pig produced, with a mean of 9.06 pigs weaned/litter and 2.327 litters produced/sow each year. Several alternative options are simulated. Of these, the ones that increase the litter size at weaning appear most beneficial in terms of both biological and economic efficiencies.

Five hundred forty crossbred pigs were utilized in four trials (10 replications) at two stations to determine the separate and interacting effects of decreasing floor space allowance with or without the addition of virginiamycin to the diet on performance of growing-finishing pigs. Pigs were allowed .37, .33 or .28 mVpig during the growing phase (23 to 55 kg) and .74, .66, .56 m2/pig during the finishing phase (55 to 100 kg) and fed either a corn-soybean meal control diet or the control diet plus 11 mg of virginiamycin/kg of diet. Floor space allowances were achieved by varying pen size, so the number of pigs and feeder space per pig were constant for all pens. During the growing phase, daily gain (P<.01) daily feed intake (P<.05) and feed conversion ratio (P<.05) decreased as floor space allowance decreased. During the finishing phase and for the total test period, daily gain (P<.01) and feed conversion ratio (P<.05) were reduced but daily feed intake was not affected (P>.05) by restricted floor space allowance. The addition of virginiamycin to the diet had no effect on pig performance. The virginiamycin × floor space allowance interaction was not significant, suggesting that pigs fed a diet with or without virginiamycin responded similarly to restricted floor space allowance. The data suggest that the addition of virginiamycin to the diet was ineffective in overcoming the decrease in performance of growing-finishing pigs caused by crowded conditions.

One hundred ninety-two crossbred pigs (61 kg) were allotted by weight to a randomized complete-block design of four treatments with six blocks per treatment and eight pigs per totally slatted, concrete pen. Pigs were allowed ad libitum consumption of either a corn-soybean meal control diet or the control diet plus cimaterol (CL 263,780) at .25, .50 or 1.00 mg/kg of diet. Cimaterol is a repartitioning agent recently identified by American Cyanamid Company. Pigs were slaughtered at an average pen weight of 105 kg. Average daily gain and feed conversion ratio were not affected (P>.10) by diet. Daily feed intake decreased linearly (P<.01) as cimaterol increased in the diet, but the response was inconsistent because pigs fed diets containing 0 and . 50 mg of cimaterol/kg of diet ate more feed than pigs fed diets containing .25 and 1.00 mg of cimaterol/kg of diet (cubic effect of diet, P<.01). Locomotive soundness scores were not affected (P>.10) by diet. The addition of cimaterol to the diet of finishing pigs resulted in a linear increase in longissimus muscle area (P<.05) and predicted kg of muscle (P<.01). Fat depth, average backfat and ham and loin fat decreased linearly (P<.01) as cimaterol increased in the diet. Pork carcass grade improved (P<.01) as cimaterol increased in the diet. Dressing percentage, carcass length, muscle score and color of lean score were not affected by diet. These results suggest that the addition of cimaterol to the diet resulted in an increase in muscle accretion and a decrease in fat deposition, resulting in a significant improvement in carcass leanness.

The fatty acid composition of subcutaneous adipose tissue from three lines of swine (genetically selected obese and lean and a contemporary crossbred line) was determined during the growing period between 3 and 6 months of age. The developmental pattern for individual fatty acids was complex, and breed × age interactions generally were observed. There were more saturated fatty acids in the obese swine than in the other two breeds, primarily the result of greater amounts of 14:0 and 16:0 acids and less 18:2 acid. The degree of saturation may result from genetic selection via unknown mechanisms, from selection for altered lipid metabolism, e.g., increased de novofatty acid synthesis in the obese relative to the other breeds — or from the extent of obesity. The tendency for the proportion of saturated fatty acids to increase in all breeds with age also may be associated with the extent of obesity.

The effects of age on lipogenic and lipolytic activities in several breeds of swine were investigated. Females from a contemporary line and genetically selected populations of lean and obese pigs were utilized. Subcutaneous adipose tissue samples were taken from the shoulder area of nonfasted animals at 28-day intervals from 3 to 6 months of age for determination of in vitrolipogenic, lipolytic and acetyl CoA carboxylase activities. There were no significant differences between the breeds in the in vitrolipogenic rates measured in tissue slices with 14C-glucose as substrate, except at 6 months of age, when the rate was higher in the obese than in the lean animals. However, the trend each month was obese> contemporary> lean. Lipogenic activity was greatest in all breeds at 4 months of age. Acetyl CoA carboxylase activity closely paralleled the lipogenic activity. The in vitrounstimulated lipolytic rate measured in tissue slices by the release of fatty acids to the incubation medium was similar for all breeds and decreased with age. Lipogenesis appears to be more important than unstimulated lipolysis in regulating backfat thickness in the breeds of swine examined.

The apparent metabolizable energy (ME) content of condensed fermented corn solubles with germ meal and bran (DSLC) was determined in a series of trials with growing pigs and gravid and nongravid female swine. DSLC was substituted for 10 or 20% of a fortified corn-soybean meal basal diet.Estimated ME corrected for nitrogen balance was 3.79 kcal/g dry matter. Metabolizable energy as determined using gravid females tended to be higher than that found in growing pigs or nongravid females. Nitrogen retention was depressed with each increment of dietary DSLC. Concomitant increases occurred in urinary and fecal nitrogen levels suggesting both poor amino acid pattern and protein digestibility.

A combination of sodium caseinate and sweet dried whey was compared to dried skim milk as a protein source for artificially reared piglets. Rate and efficiency of gain, diet consumption, frequency of diarrhea, nutrient balance and characteristics of the gastrointestinal tract and its contents were observed in piglets fed these protein sources. Rats were fed the same protein sources with rate and efficiency of gain, diet consumption, and frequency and severity of diarrhea observed. The combination of sodium caseinate and sweet dried whey was inferior to dried skim milk as a protein source for artificially reared piglets, the rate of gain being only 80 to 83% as fast for the group fed the casein-whey diet as for those fed the dried skim milk diet. Rats responded similarly. In both species the depressed rate of gain on the casein-whey diets was associated with more frequent diarrhea. Balance data did not show the dried skim milk diet to be superior, but reliable fecal collections could not be obtained from severely scouring piglets. No treatment differences were observed in the pH of the gastrointestinal tract contents, weight of empty stomach or histology of the gastrointestinal tract. Weight of stomach contents was greater in piglets fed the casein-whey diet.

Three experiments involving 200 pigs were designed to determine the value of corn solubles with germ meal and bran (DSLC) as an amino acid source when substituted for part of the corn and soybean meal. In each of these studies, diets were formulated to meet the lysine requirement, based on the initial weight of the pigs.For young pigs DSLC was substituted to provide up to 30% of the total lysine in the diet. Performance at the highest level was equal to that of the pigs fed the corn-soybean meal diet. For finishing pigs DSLC was substituted to provide up to 36% of the total dietary lysine. As with the young pig, the performance of finishing pigs fed diets with the upper level of DSLC was similar to that of pigs fed the corn-soybean meal diet. DSLC can be considered an effective amino acid supplement for cereal grains when used at levels tested in these studies.

Five experiments were conducted with 282 finishing pigs to evaluate the use of condensed fermented corn solubles with germ meal and bran as an amino acid source for swine. This wet milling byproduct referred to as dried steep liquor concentrate (DSLC) is becoming a major byproduct of the industry as methods of corn processing change. DSLC serving as the only amino acid supplement for corn supported much lower gain and efficiency in finishing pigs than did a corn-soybean meal diet. In corn-DSLC diets designed to meet the requirements for lysine and tryptophan performance could not be markedly improved by supplementing with either of the two amino acids singly. However, performance was greatly improved when both amino acids were added to the diet. The experiments clearly demonstrate that lysine and tryptophan in DSLC have limited biological availability.

An initial study was conducted with 37 crossbred sows to compare the efficacy of dicalcium, soft and Curacao phosphates as supplements for a corn-soybean meal diet during gestation and lactation. Reproductive performance was similar whether the gilts received the diet unsupplemented or supplemented with one of the three phosphorus supplements. There was a high incidence of posterior paralysis during the sixth to eighth week of lactation in sows fed the unsupplemented diet. Paralysis was also observed, but to a lesser incidence, in sows fed soft or Curacao phosphates.Reproductive performance was not significantly (P< .05) affected in a second study with 70 first-litter sows fed the same diets. During the 36-day lactation, phosphorus digestibility, retention and balance (corrected for milk phosphorus) were similar for sows fed the supplemented diets but much lower for those fed the basal diet. Bone ash and phosphorus and bone strength criteria were lower for sows fed the unsupplemented diet than for those fed dicalcium or Curacao phosphate. Values for sows fed soft phosphate were intermediate between the unsupplemented group and those receiving the other supplements. Two sows on the unsupplemented diet developed posterior paralysis after the litter was weaned and the sows were grouped. A phosphorus level of 0.5% during gestation and lactation appears adequate for all criteria measured when feeding either dicalcium or Curacao phosphate.

Three studies were conducted with 86 litters containing 807 pigs to evaluate two methods of iron dextran administration and the affect of type of floor. Iron dextran was shown to be effective as a hematinic for 28 days whether injected intramuscularly or administered orally within the first 12 hr. of life, prior to closure of the intestine to absorption of large molecules. Pigs farrowed and raised on steel-slatted floors maintained adequate hemoglobin values with no other iron treatment. Pigs managed similarly on steel slats coated with epoxy developed anemia by 14 days.