Lead inclusion bodies in osteoclasts.

Inclusion bodies occur frequently in the nuclei and rarely in the cytoplasm of osteoclasts in pigs with experimental lead poisoning. The light and electron microscope pictures of undemineralized sections are similar to those described for liver cord cells and renal tubular cells.

Porcine adrenal adrenocorticotropic hormone receptors: characterization, changes during neonatal development, and response to a stressor.

ACTH receptors were characterized in the porcine adrenal cortex using a biologically active [125I] Tyr23,Phe2,Nle4ACTH(1-38) analog, and a 149,000 X g(av) total particulate tissue preparation. Binding of this labeled ACTH analog to adrenocortical ACTH receptors was demonstrated to be time and temperature dependent, tissue and hormone specific, saturable, reversible, have a binding optimum at pH 7.5, and be dependent on the presence of Ca++. Scatchard analyses of saturation data using the computer program LIGAND indicated a single class of high affinity binding sites [association constant (Ka) = 2.00 +/- 0.25 10(9) M-1)]. Hill plots of saturation data had slopes (b = 0.83 +/- 0.09) that did not differ from 1, and hence also indicated a single class of binding sites. The rate constant of association (k1 = 3.72 +/- 1.19 X 10(8) min-1M-1) was compatible with the known rapidly occurring action of ACTH in pigs in vivo. Kinetic experiments also indicated the ACTH receptors to be of high affinity (4.18 +/- 0.54 X 10(10) M-1; n = 4). Receptor-associated degradation occurring to analog during incubations involved cleavage of the peptide into fragments rather than deiodination and could be partially prevented by use of 0.01% bacitracin. Subsequently, a study was conducted to determine changes in the ability of piglets to respond, in terms of plasma cortisol, to the physiological and psychological stressor of overnight maternal deprivation (MD) at various neonatal ages (days 3-31 of age); to measure age-related and stressor-associated changes in adrenal ACTH receptors; and to associate any changes in adrenal response with changes in ACTH receptors. Plasma cortisol obtained by venipuncture did not vary with age in either control or MD piglets but was elevated by MD (16.98 +/- 2.5 vs. 68.3 +/- 8.2 ng/ml). There was no effect of MD and associated hormonal perturbations on adrenal ACTH receptors. However, there were significant age-related differences in these receptors, with a 1.6-fold increase in concentrations (55.6 +/- 12.0 fmol/mg protein), and a 63% decrease (P less than 0.05) in affinity (4.19 +/- 0.86 x 10(8) M-1) evident at 17 days of age compared with 10 and 24 days of age. The significance of these age-related changes in ACTH receptors for adrenal function remains to be determined; however, it is evident that in neonatal pigs, there is no stress nonresponsive period.

Accuracy of dual-energy x-ray absorptiometry for body-composition measurements in children.

The accuracy of body-composition measurements by dual-energy x-ray absorptiometry (DXA) was assessed by comparison with total carcass chemical analysis in 16 pigs with a weight range of 5-35 kg. Two software versions for body-composition analyses with the DXA instrument were evaluated. Although both software versions accurately predicted body weight, there were significant differences in the partitioning between bone mineral content (BMC), nonbone lean tissue, and body-fat compartments. All estimates of body composition were highly correlated (r2 > or = 0.98) with the results of the direct chemical reference method. SEEs were 226-271 g for body weight, 387-429 g for fat, 3.5-4.3 kg for fat-free mass, and 35.4-36.5 g for BMC. For bone, both software versions produced BMC values that were approximately 25% below the total carcass ash content. For the absolute mass of body fat, one DXA analysis provided underestimates that averaged 19.5% below the reference chemical method, whereas the alternate software version resulted in over-estimates, averaging 15.5%. Conversely, the average fat-free compartment was initially overestimated by 968 g, then underestimated by 892 g. The impact of these differences in the body-composition analyses by DXA were examined in a group of 18 young boys 4-12 y of age.

Ontogeny of immunoreactive CCK and VIP in pig brain and gut.

The concentrations and hormonal forms of CCK and VIP have been determined in extracts of the brain and duodenum of the developing and adult pig. In methanol extracts of the brain cortex, the single hormone form, CCK8, increased from 130 +/- 20 (Mean +/- SEM) pmol/g at birth to an adult level of 300 +/- 50 pmol/g. In acid extracts of brain, the predominant immunoreactive form had N-terminal immunoreactivity and increased from 240 +/- 20 pmol/g at birth to an adult level 490 +/- 30 pmol/g; the C-terminal immunoreactivity was about 10-fold lower. The concentrations and hormonal forms of immunoreactive CCK in duodenal extracts did not appear to be age-related. C-terminal immunoreactivity in methanol extracts averaged 140 +/- 20 pmol/g and in acid extracts 240 +/- 60 pmol/g. The concentration of N-terminal immunoreactivity in acid extracts averaged 490 +/- 70 pmol/g. The VIP concentrations in acid extracts of the brain cortex was 13.5 +/- 2 pmol/g at birth and rose gradually to 30 +/- 9 pmol/g in the adult; in duodenal extracts it was 240 +/- 18 pmol/g at birth and 195 +/- 38 pmol/g in the adult. These results are in marked contrast with the ontogeny of these hormones in the rat in which brain concentrations of CCK and VIP in the neonate are less than 10% of adult levels and in which there are age-related changes in the content of these hormones in the duodenum as well.

Protein restriction in early pregnancy alters fetal and placental growth and allantoic fluid proteins in swine.

This study was designed to determine the impact of protein malnutrition during early pregnancy on fetal and placental growth and on the protein synthesis capacity of placental and endometrial tissues. Twelve crossbred sows received 1.8 kg/d of a control (13% protein) or protein-restricted (0.5% protein) diet from the day of breeding to Day 63 of pregnancy, when dissections were performed on each conceptus unit. The de novo protein synthetic rate of placental and endometrial explants was measured using (35)S-methionine. These proteins and the proteins from amniotic and allantoic fluids were separated by polyacrylamide gel electrophoresis. Placental weight was significantly reduced in the sows fed the restricted diet, with a tendency for decreased fetal weight as well. No differences were found due to dietary treatment in de novo protein synthesis or in the electrophoretic patterns of secreted proteins of the placenta or endometrium. The apparent quantity of 3 proteins in the allantoic fluid of the restricted diet fetuses decreased, while 1 protein increased in comparison with that of the control fetuses. These data suggest that protein malnutrition in early pregnancy decreases placental growth, thereby decreasing both fetal growth and the opportunity for compensatory growth upon nutritional rehabilitation.

Effects of dietary protein level and clinoptilolite on the weight gain and liver mineral response of growing lambs to copper supplementation.

Growing male Synthetic I (1/2 Finnish Landrace x 1/4 Dorset x 1/4 Rambouillet) lambs were used in two experiments (64 lambs in Exp. 1 and 63 in Exp. 2) to test the hypothesis that dietary CP level (9 or 14% of diet as fed) and(or) clinoptilolite (clino; 0 or 2% of diet) affects growth and tissue mineral concentrations of growing lambs fed supplemental Cu. Lambs were individually fed their respective diets ad libitum and killed after 12 wk (Exp. 1) or 16 wk (Exp. 2) to obtain carcass measurements, organ weights and liver mineral concentrations. In Exp. 1, 20 ppm added Cu (as CuSO4.5H2O) increased mortality and depressed BW gain (P less than .01) and daily feed intake (P less than .05) in the presence or absence of clino and at both levels of CP. Liver Cu concentration was greater (P less than .01) in lambs fed added Cu than in those not fed Cu (408 ppm vs 110 ppm, respectively). Neither CP nor clino affected liver Cu concentration. Clinoptilolite increased daily gain of lambs fed high CP but not low CP (P less than .01). In Exp. 2, clino in the diet had no effect on daily gain or daily feed, but 20 ppm Cu addition depressed daily gain (P less than .01) and gain/feed (P less than .07). Organ weights and levels of trace elements other than Cu in the liver generally were not affected by diet in either experiment. It is concluded that high dietary CP or 2% dietary clino did not protect against toxic signs of Cu when Cu was added to the basal diet (10 ppm Cu) at 10 or 20 ppm.

Effect of dietary calcium and zinc levels on weight gain and blood and tissue mineral concentrations of growing Columbia- and Suffolk-sired lambs.

One hundred and sixty Columbia- and Suffolk-cross intact male and female growing lambs (8 wk of age) were used in an 84-d feeding trial to determine the effect of two levels dietary Ca and Zn on weight gain, feed utilization and several blood and tissue traits. Two levels of Ca (.5 and .8%) and two levels of Zn (20 and 100 ppm) were fed in a 2 X 2 factorial arrangement of dietary treatments. There was no effect of diet on performance or on blood traits. Columbia lambs had heavier fleeces at slaughter than Suffolks (P less than .01) and males had heavier fleeces than females (P less than .01). Based on the similarity in performance among lambs fed the four diets differing in Ca and Zn level, it is concluded that a dietary Ca level of .5% and a Zn level of 19 to 26 ppm is adequate for normal weight gain, feed utilization, liver and humerus ash concentrations and blood plasma concentrations of Ca, P, Zn, total protein, albumin, alkaline phosphatase and blood hemoglobin and hematocrit. Further, it appears that an elevated level of dietary Ca does not precipitate a clinical Zn deficiency in the growing lamb, in contrast to the general observation in growing swine.

Thoughts on fiber utilization in swine.

There is continued incentive for the development of alternative feed resources for use in swine production. The availability of distillery by-products may be expected to increase as the use of corn and cereal grains for ethanol production expands. The acceptability of distillery by-products, milling by-products, forages and other fibrous feeds as energy sources for swine depends on such factors as cell wall content of the plant, degree of microbial fermentation in the large intestine, and extent of absorption and utilization of the volatile fatty acids produced. Physiological effects of dietary fiber, including effects on gastric emptying, rate of transit of digesta, gut motility, digestive secretions, and absorption and utilization of breakdown products need quantification. Limited evidence suggests that there are genetic differences in the response of pigs to dietary fiber and in their ability to utilize it as an energy source. Recombinant DNA technology offers the possibility of cloning cellulase genes from microorganisms for application in swine feeding programs. The extent to which biotechnology will be applied in swine feeding will depend ultimately on the economic incentive for developmental effort and on unknown biological limitations of the pig and its gastrointestinal microbial ecosystem.

Effect of protein deficiency on growth and plasma zinc concentration in genetically lean and obese swine.

Thirty-two genetically lean and 32 genetically obese weanling (4 to 5 wk old) pigs from inter se matings of crossbreds produced by within-line matings of Duroc and Yorkshire breeds, selected for low or high backfat, were fed the following four diets for 8 wk (eight lean and eight obese pigs/diet): 10% protein -- 100 ppm Zn, 10% protein -- 200 ppm Zn, 18% protein -- 100 ppm Zn, 18% protein -- 200 ppm Zn. After 8 wk, all pigs were fed a standard 16% protein corn-soybean meal-type growing diet to a slaughter weight of about 87 kg. Lean pigs were more severely affected than obese pigs by low protein diets as measured by weight gain, plasma total protein and plasma albumin. Plasma Zn concentration was reduced in lean and obese pigs fed low protein diets. Supplemental Zn failed to increase plasma Zn in protein-deficient pigs. During repletion, weight gain of lean and obese pigs previously fed the 10% protein -- 100 ppm Zn diet was less than that of pigs previously fed other diets. The lower level (100 ppm) of Zn fed during protein depletion appeared to be associated with a negative effect on repletion weight gain of lean and obese pigs. Lean and obese pigs responded similarly during the repletion phase to earlier protein restriction. We conclude that supplementary dietary Zn does not maintain plasma Zn concentration in growing pigs fed protein-deficient diets and that repletion from dietary protein restriction is not associated with compensatory growth in genetically lean pigs.

Responses of weanling pigs to dietary supplementation with vitamin C or carbadox.

A 2 X 2 factorial arrangement with two levels (0, 660 ppm) of vitamin C and two levels (0, 55 ppm) of carbadox supplementation was used in two experiments with 112 crossbred pigs weaned between 4 and 5 wk of age. An 18% protein corn-soybean meal-oats-dried whey starter diet was used as the basal diet. Each diet was fed ad libitum for a 4-wk period to three replicates of four pigs in Exp. 1 and to four replicates of four pigs in Exp. 2. Vitamin C supplementation produced a significantly higher plasma vitamin C concentration in weanling pigs, but, contrary to results of our previous study, failed to improve average daily gain of the pigs. Daily gain was, however, improved significantly by carbadox supplementation. Carbadox also produced a significantly higher plasma vitamin C concentration in pigs after a 7-d lag period. Plasma Fe concentration of pigs was not affected by supplemental vitamin C, but was significantly higher in those fed carbadox-supplemented diets. Plasma ceruloplasmin concentration increased significantly in all treatment groups from the initial sampling period (d 0) to subsequent periods. No interactions between supplemental vitamin C and carbadox were observed in daily gain, feed efficiency and the measured plasma constituents.

Effect of dietary vitamin C addition on performance, plasma vitamin C and hematic iron status in weanling pigs.

Each of 64 pigs weaned between 4 and 5 weeks of age was fed ad libitum one of four diets: (1) a basal 18% crude protein, corn-soybean meal-oats-dried whey starter diet or (2,3,4) the basal diet supplemented with 330, 660 or 990 ppm L-ascorbic acid (vitamin C). The pigs were kept in groups of four and housed in an environmentally regulated nursery with a raised, expanded metal floor. The room temperature was maintained at 21 C and floor allowance was .54 m2/pig. After 28 days, dietary vitamin C supplementation had improved daily weight gain and daily feed intake of pigs without altering gain to feed ratio. Plasma vitamin C concentration decreased during the 4 weeks period after weaning in pigs not fed supplemental vitamin C but not in those fed supplemental vitamin C. Plasma Fe was reduced at day 28 in pigs given supplemental vitamin C. Simple correlation indicated a positive (P less than .05) relationship between plasma vitamin C concentration and weight gain and a negative (P less than .05) relationship between plasma vitamin C and plasma Fe concentration. Results obtained suggest that, under the experimental conditions, young pigs weaned between 4 and 5 weeks of age require dietary vitamin C supplementation for maximum weight gain and that the benefit of vitamin C addition may be related to Fe metabolism.

Plasma thyroid hormones, growth and carcass measurements of genetically obese and lean pigs as influenced by thyroprotein supplementation.

A 2 X 2 factorial arrangement with two genotypes of pigs (genetically obese and lean) and two dietary treatments (basal, a 16% protein corn-soybean meal standard grower diet, and basal +220 ppm thyroprotein as iodinated casein) was used. The 28 gilts were housed individually and fed ad libitum from 121 d of age until slaughtered at 99 kg body weight. Compared with lean pigs, genetically obese pigs had significantly lower average daily gain and gain/feed, greater backfat thickness, smaller loin eye area, shorter carcass length and lower circulating plasma triiodothyronine (T3) concentration. However, both total plasma and free thyroxine (T4) concentrations were similar comparing obese and lean pigs. Supplementation with thyroprotein increased circulating plasma concentration of both total and free T4 and produced interactions with genotype in affecting daily gain and gain/feed of pigs. Thyroprotein reduced both daily gain and gain/feed in obese pigs, but increased daily gain and gain/feed in lean pigs. It is suggested, similar to the case with obese mice, that heat production of our genetically obese pigs may be more sensitive to thyroprotein administration compared with similar treatment of lean animals.

Effect of carbadox on net absorption of ammonia and glucose into hepatic portal vein of growing pigs.

Chronic cannulas were placed into the hepatic portal vein, ileal vein and carotid artery of growing pigs trained to consume their daily allowance of 1.2 kg of feed (16% protein corn-soybean meal basal diet) in a single meal. The average preoperative BW of pigs was 44.7 kg for Trial 1 (three pigs) and 35.3 kg for Trial 2 (seven pigs). In Trial 1, net absorption of ammonia (NH3) and glucose into the portal vein was determined three times at weekly intervals. The net portal absorptions were derived by multiplying the porto-arterial plasma concentration difference of NH3 and glucose by portal vein plasma flow rate estimated with the p-aminohippuric acid indicator-dilution technique. Differences in the net portal absorptions of NH3 and glucose among the three weekly measurements were small (P greater than .05). In Trial 2, the first sequence of net portal absorption measurements was conducted when pigs were fed the basal diet, and the second sequence of measurements was conducted after the pigs had been fed the diet supplemented with 55 ppm of carbadox for 7 d. Carbadox supplementation reduced (P less than .05) plasma NH3 concentration in portal plasma during the 2.5-h to 5-h postprandial period and decreased (P less than .05) net portal absorption of NH3 during the 2.5-h to 4-h postprandial period. Carbadox, however, did not affect (P greater than .05) net portal absorption of glucose. We suggest that carbadox suppresses the production of cell-toxic NH3 by intestinal microorganisms and, thus, reduces the injury and turnover of intestinal cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential compensatory growth in swine following control of feed intake by a high-alfalfa diet fed ad libitum or by limited feed.

Seventy-two castrated male four-way composite (Chester White x Landrace x Large White x Yorkshire) weanling pigs (17 kg initial BW) were used to determine the compensatory response of specific organs and whole body following a 3-wk period of restricted energy intake imposed by ad libitum-feeding an 80% alfalfa meal diet or pair-feeding an adequate corn-soybean meal diet to attain equal weight loss. Six pigs were killed at d 0 to provide baseline data. Six pigs from each diet group (control, C; alfalfa, A, restricted, R) were killed at d 21, after which all remaining pigs were fed C ad libitum to 35 d, 105 d or 126 d. Six pigs per group were killed at 35 and 105 d and four per group were killed at 126 d. Organ weight and carcass data were recorded for all pigs at all time intervals. Regression of organ and trimmed lean tissue weights on time was tested for linearity (d 1 to 126 for C and d 21 to 126 for A and R except d 35 to 126 for gastrointestinal tract traits for A and R); differences in organ weights between C, A and R at d 21 and d 35 were tested by a two-way analysis of variance. There was no evidence of a compensatory growth response to dietary energy restriction for 21 d except for rate of change in weights of liver and kidneys and backfat depth from 21 to 126 d and of gastrointestinal tract components from 21 to 35 d. Specific organs may exhibit compensatory growth over different time spans in young pigs in the absence of observable weight compensation at the whole-animal level.

Nutritive value of a vegetable amaranth cultivar for growing lambs.

Current interest in amaranth as a food resource for humans and animals has been stimulated by activities in germplasm collection and testing in the U.S. Fifteen growing, intact male lambs weighing 18.7 kg were assigned randomly to three diets (five lambs/diet) for a 14-d growth trial followed immediately by an 8-d (4-d adjustment, 4-d collection) digestion and N balance trial to determine the utilization of the forage component (leaves and stems) of an African cultivar (Zimbabwe cultivar PI 482049, Amaranthus cruentus L.) All diets contained 40.95% ground corn, 8.0% soybean meal and 1.05% mineral-vitamin supplement plus either 50% ground alfalfa hay, 25% ground alfalfa hay plus 25% ground amaranth forage or 50% ground amaranth forage. Lambs had ad libitum access to feed during the growth trial and at 4% of BW daily during the digestion and N balance period. Replacement of half or all the alfalfa in the diet with amaranth had no effect on weight gain or feed utilization. Apparent digestibility of cell contents, NDF, ADF, cellulose, ADL, N and GE and percentage of absorbed N retained did not differ among the three diets. The amaranth vegetable cultivar Zimbabwe PI 482049 promoted weight gain and feed utilization equal to that obtained with alfalfa as the sole forage for growing lambs. Additional research is needed to evaluate further the potential role of forage/vegetable amaranth as an animal feed resource.

Response of swine to periparturient vitamin C supplementation.

Two experiments were conducted, involving 68 third-litter sows and 20 first-litter gilts in Exp. 1 and 82 first-litter gilts in Exp. 2. On d 108 of gestation, the dams were moved into individual crates, stratified by parity and breed, and randomly assigned within strata, to one of two treatments: (1) fed a basal 16% protein corn-soybean meal diet, 1.8 and 2.7 kg once daily before farrowing and for the first 7 d of lactation, respectively, and then ad libitum until pigs were weaned at 28 d of age, and (2) fed the basal diet plus 1 g of L-ascorbic acid (vitamin C)/dam daily from d 108 of gestation through d 7 of lactation and on the same feeding schedule as for treatment 1. In Exp. 1, no effect of vitamin C supplementation was observed in sows or gilts on total pigs born/litter, number of live pigs/litter or average live pig weight at birth, 7 or 28 d of age, or on plasma vitamin C concentration of dams at d 108 of gestation or d 7 of lactation or of pigs at birth, 7 or 28 d of age. However, there was a lower (P less than .01) plasma vitamin C concentration of the dams at d 7 of lactation than at d 108 of gestation. Plasma vitamin C concentration also declined (P less than .01) as pigs aged. In Exp. 2, with all gilts, vitamin C supplementation again showed no effect on any of the reproductive traits measured in Exp. 1. It is concluded that daily supplementation of 1 g of vitamin C to either sows or gilts from d 108 of gestation through d 7 of lactation has no beneficial effect on the reproductive or lactation performance of swine.

Effects of carbadox, copper, or Yucca shidigera extract on growth performance and visceral weight of young pigs.

Two identical trials, each with 128 crossbred weanling barrows (6.8 +/- .2 and 7.6 +/- .2 kg for Trials 1 and 2, respectively), were conducted. In each trial, pigs were allowed to consume ad libitum a 16% CP corn-soybean meal basal diet (B), B + 55 ppm of carbadox, B + 250 ppm of copper (Cu), or B + 125 ppm of Yucca shidigera extract for 56 d (four pens/diet; eight pigs/pen). At d 56 of the test, eight pigs/diet (two pigs/pen) were slaughtered for carcass and viscera measurements. Data of carbadox treatment in Trial 1 are excluded from this paper because of an error in mixing of the diet. In Trial 1, during the test period from d 0 to 28, pigs fed Cu had greater (P < .05) ADG and ADFI than those fed B, whereas pigs fed yucca extract had higher ADFI (P < .05) but similar ADG (P > .05) compared with those fed B. During the period from 29 to 56 d, ADG was similar among pigs fed different diets (P > .05) but ADFI was affected (P < .05) by diet (yucca extract > Cu > B). No differences (P > .05) among diets were detected for gain/feed (G/F) and visceral weights expressed as a percentage of slaughter BW. In Trial 2, during the first 28 d, the ADG, ADFI, and G/F responses of pigs to Cu, yucca extract, and B were similar to those observed in Trial 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of gestation-lactation diet calcium and zinc levels and of parenteral vitamins A, D and E during gestation on ewe body weight and on lamb weight and survival.

Data on ewe body weights and on lamb birth and weaning weights and survival rates were recorded on a total of 557 multiparous Rambouillet, Hampshire X Suffolk and Synthetic I (composite of Finnish Landrace, Rambouillet and Polled Dorset) ewes in two experiments started after the first trimester of gestation. In Exp. 1, a 2 X 2 factorial arrangement of treatments included all combinations of low (.24% in gestation and .48% in lactation), or high (.80%) dietary Ca and low (20 ppm) or high (74 ppm) dietary Zn. No effect of dietary Ca or Zn level and no Ca X Zn interaction with respect to number of lambs born or weaned, birth weight, weaning weight or survival rate of the lambs or body weight of the ewes was shown. Mean number of lambs born was 1.63 +/- .71 with a survival rate of 85.0 +/- .3% and a weaning weight (59 d) of 19.4 +/- 4.4 kg. Experiment 2 was a repeat of Exp. 1 except that two intramuscular injections of vitamins A, D and E (d 65 and 93 of experiment) were given to one-half of the ewes in each diet group. There was no effect of dietary Ca or Zn level or of vitamin administration on ewe body weight changes, number of lambs born (1.89 +/- .55), survival rate (86.6 +/- .3%), lamb birth weight 4.6 +/- 1.5 kg) or lamb weaning weight (23.2 +/- 7.2 kg). Blood plasma Ca, inorganic P and Mg concentrations of ewes in late pregnancy were unaffected by diet or vitamin injections.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary supplementation with vitamin C or carbadox on weanling pigs subjected to crowding stress.

A 2 X 3 factorial arrangement was used in each of two trials with two levels of floor space allowance (.25, .13 m2/pig) and three dietary treatments (basal, basal + 660 ppm vitamin C, basal + 55 ppm carbadox). The reduction in floor space allowance was achieved in trial 1 by doubling the number of pigs/pen from eight to 16 and in trial 2 by reducing the size of pens by half. An 18% protein starter diet was used as the basal diet. Total numbers of pigs used were 216 in trial 1 and 144 in trial 2. Pigs were weaned between 4 and 5 wk of age (7.5 kg average wt) and fed ad libitum for 28 d. Reducing floor space allowance caused a (P less than .05) reduction in weight gain of weanling pigs in both trials. When the reduction of floor space allowance was done by increasing number of pigs/pen (trial 1), pigs responded with a significantly reduced feed intake with no change in efficiency of feed utilization. However, when floor space allowance was reduced by changing the size of the pen (trial 2), feed intake of pigs was not affected but efficiency of feed utilization was reduced significantly. Neither form of crowding affected vitamin C concentration in adrenal glands and weights of adrenal glands, spleen and thymus. Dietary supplementation of carbadox, but not vitamin C, produced significantly greater weight gain, feed efficiency, and spleen weight of pigs in both trials. Although there was no interaction between crowding and dietary treatment in affecting the performance of pigs, supplemental carbadox improved the performance of crowding-stressed pigs by maintaining an adequate level of feed intake and improving feed efficiency, whether crowding was caused by increased pig density or by reduced pen size. No significant differences in phytohemagglutinin (PHA) skin test response or in the neutrophil-to-lymphocyte ratio (N/L) were observed among treatments in trial 1, while a significantly reduced response to PHA and a higher N/L were detected in crowding-stressed pigs in trial 2.

Reproductive, endocrine, and organ weight differences of swine selected for high or low serum cholesterol.

Three generations of selection for 56-d blood cholesterol concentrations were used to establish low and high cholesterol lines of pigs in which cholesterol concentrations differed by 39% in the last generation. Litter size (number of fully formed pigs born per litter) diverged with each successive generation of selection and, at the third generation, litter size differed between the low and high line by two pigs (high line = 8.5 +/- .6; low line = 10.5 +/- .5; P < .05). A random selection of offspring (gilts, n = 109; boars, n = 46; barrows, n = 94) from the third generation and a control line maintained throughout the experiment were monitored for hormonal and anatomical relationships that might provide insight into the mechanisms that altered fecundity. Ovulation rate (number of corpora lutea) as determined on d 60 of pregnancy was increased in the low (n = 29) compared with the high cholesterol line (n = 38; 11.8 +/- .3 vs 9.8 +/- .3, respectively; P < .05), and litter size continued to be increased in the low cholesterol line (P < .05). No differences were noted between lines in kidney, ovarian, or total corpora lutea weight. Empty uterine weight and adrenal weight were increased in the high cholesterol line (P < .05) in randomly selected offspring of the third generation, and liver weight increased in the low line (P < .05). Associated with increased concentrations of cholesterol were increased serum concentrations of progesterone (gilts) and testosterone (boars) in the high cholesterol line (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)