Consequences of severe copper deficiency are independent of dietary carbohydrate in young pigs.

The ability of carbohydrates (CHO), such as fructose and sucrose, to aggravate copper deficiency in rats and the recent dietary trends of Western human populations led to the suggestion that the Cu X CHO interaction may be pertinent to public health. This hypothesis was tested with pigs because their cardiovascular and gastrointestinal systems closely resemble those of humans. Weanling pigs were fed a diet containing either 59% sucrose or cornstarch with either deficient (0.8 mg/kg diet) or adequate (6.4 mg/kg) copper for 10 wk. Plasma and tissue copper, the activities of plasma ceruloplasmin ferroxidase and erythrocyte Cu,Zn-superoxide dismutase, hematocrits, and serum cholesterol and triglyceride were all decreased (p less than 0.05) and relative cardiac mass was increased (p less than 0.05) by severe dietary copper deficiency. The type of dietary CHO did not differentially influence the values of these variables. Thus, these data fail to support the hypothesis that the Cu X CHO interaction observed in rats represents a health risk for humans.

Dietary copper, simple sugars, and metabolic changes in pigs.

Inadequate dietary copper is known to result in undesirable metabolic changes in rats and humans. Abnormal cardiac function, leading to sudden death, is a common finding when copper deficient rats are fed a 62% fructose diet. To further study the apparent mineral-carbohydrate relationship to cardiac physiology, 3 male and 3 female swine were randomly assigned to four groups (6 pigs per group) which were fed low copper (1.5 ppm) or copper supplemented (40 ppm) diets with 20% of calories from either fructose or glucose for 10 weeks. In agreement with results from other animal studies, copper deficient swine exhibited decreased plasma ceruloplasmin, erythrocyte superoxide dismutase and plasma lysyl oxidase activities and lowered serum copper. The copper deficient fructose group had the lowest aortic lysyl oxidase activity and hematocrit when compared to the other groups. The relative heart weight in the copper deficient fructose group was 93% greater than the other three dietary groups. The livers of copper deficient fructose fed pigs were also significantly larger. Two enzymes related to cardiac and hepatic function, aspartate and alanine aminotransferase were also measured. Copper deficiency significantly lowered alanine aminotransferase but there was no dietary effect on aspartate amino-transferase. The results of this project indicate that the pig is a sensitive model for the study of cardiovascular abnormalities which occur when fructose is consumed with a low copper diet.

Effects of growth hormone administration on vitamin D metabolism and vitamin D receptors in the pig.

Twelve 36-kg pigs were given either 100 micrograms/kg porcine pituitary growth hormone (pGH) or placebo injections daily for 33 days. Serum was obtained weekly for analysis of minerals and vitamin D metabolites. On day 34, the pigs were sacrificed and renal and duodenal tissue were obtained for analysis of vitamin D receptor content (VDR). Animals treated with pGH grew faster and had a higher rate of bone accretion than did control animals. Serum concentrations of 1,25-dihydroxyvitamin D (1,25-(OH)2D) were significantly higher in pGH-treated pigs than in control pigs at all time points following initiation of treatment, with the greatest difference observed at day 28 (42.4 +/- 4.9 pg/ml in controls vs. 65.4 +/- 4.7 pg/ml in pGH-treated pigs). Serum 24,25-dihydroxy-vitamin D tended to be lower in pGH-treated pigs than in control pigs, being significantly lower on day 21 of the experiment (3.22 +/- .52 vs. 6.73 +/- 1.22 ng/ml, respectively). Serum concentrations of 25-hydroxyvitamin D and calcium were unaffected by pGH treatment. Kidneys of control pigs contained significantly more unoccupied vitamin D receptors than did kidneys from pGH-treated pigs (73.3 +/- 4.3 vs. 58.3 +/- 4.1 fmoles/mg protein). Duodenal tissue unoccupied vitamin D receptor content was similar in both pGH-treated (245 +/- 17.9 fmoles/mg protein) and control (263 +/- 21.8 fmoles/mg protein) pigs. Duodenal occupied vitamin D receptor concentration was similar in both pGH-treated (6.8 +/- .75 fmoles/mg protein) and control pigs (5.32 +/- .77 fmoles/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dietary energy intake and exogenous porcine growth hormone administration on circulating porcine growth hormone concentration and response to human growth hormone-releasing factor administration in growing swine.

In a 2 x 2 treatment array (n = 4 pigs/treatment), the effects of feed intake (ad libitum vs. restricted to 60% ad libitum) and the daily administration of excipient buffer or porcine pituitary-derived growth hormone (GH) at a dose of 100 micrograms/kg body weight per day on serum GH profile and human growth hormone-releasing factor (hGRF) response were examined in barrows weighing 55 kg. Feed intake treatment was implemented from 25 to 55 kg live weight. Buffer or GH treatment was implemented for 10 d before sampling. After GH treatment, the integrated serum GH concentration area was 25% greater in barrows fed restrictively. Data are consistent with the suggestion that GH dose to improve the efficiency of lean tissue deposition be adjusted according to feeding regimen. The serum GH response to hGRF was also altered by level of feed intake. The ad libitum feeding of buffer-treated animals resulted in a monophasic serum GH response to hGRF, whereas barrows fed restrictively had a biphasic response to hGRF. Together, these data suggest that feed intake pattern alters GH secretion and as such could influence the practical implementation of somatotropin as a metabolism modifier in swine.

Long-term recombinant porcine somatotropin (PST) treatment mitigates the responses to subchronic lipopolysaccharide in swine.

The effect of multiple lipopolysaccharide (LPS) challenges in swine undergoing long-term treatment with porcine somatotropin (PST) was determined. Changes in aspartate serine transaminase (AST) occurred only at 24h following the first LPS challenge dose (P<0.05), while PST treatment moderated any change from occurring. Nonesterified free fatty acid (NEFA) levels were elevated in PST treated animals for the first 3 days following daily LPS treatment (P<0.05), while LPS treatment alone had no effect on plasma NEFA levels. Plasma urea nitrogen (PUN) levels were unchanged by LPS following the initial LPS challenge, but were decreased following the second challenge dose (P=0.014). These changes were long lasting, with a return to normal PUN levels not evident until Day 6. The PST treatment mitigated changes in PUN (P<0.05) when LPS was administered. Haptoglobin plasma levels, along with lipid peroxide production were not affected by LPS challenge or PST administration. LPS challenge reduced the levels of immunoreactive heat shock protein 70 (HSP70) throughout the entire challenge period (P<0.001). PST-LPS animals had normal levels of this protein. The results of the present study demonstrate that long-term PST treatment mitigates the adverse effects of subchronic LPS administration.

Challenge differentially affects cytokine production and metabolic status of growing and finishing swine.

Growing (35 kg body weight) and finishing (85 kg body weight) swine challenged with endotoxin (Escherichia coli O55:B5) at a dose of either 2 or 20 microg/kg produced tumor necrosis factor (TNF)alpha in a dose-response relationship as measured by bioassay. Peak TNFalpha plasma levels were observed 1-2 hr post-challenge, returning to basal values 4 hr post-challenge. However, both an enzyme-linked immunosorbent assay specific for swine TNFalpha and total human TNFalpha demonstrated no dose-response relationship; peak plasma levels of immunoreactive TNFalpha were also observed 1-2 hr post-challenge. Maximal plasma interleukin-6 levels occurred 1-2 hr post-challenge and remained elevated through 8 hr post-challenge; there was no effect of lipopolysaccharide dose or metabolic status. Although the metabolic status of the animals also affected glucose levels, with growing animals exhibiting greater sensitivity compared with finishing animals, endotoxin-induced decreases in blood glucose levels were primarily dose-dependent. In contrast, changes in plasma urea nitrogen and free fatty acid (FFA) levels were strictly related to the metabolic status. Urea nitrogen levels were unchanged in growing swine, whereas they were increased in finishing swine and remained elevated 24 hr post-challenge. FFA levels in growing and finishing swine increased 3-6 hr post-challenge. FFA levels returned to basal values for finishing swine 24 hr post challenge, but in growing swine remained elevated 24 hr post-challenge. Plasma aspartate transaminase levels were increased through 24 hr post-challenge; animals given a dose of 20 microg/kg exhibited the greatest increase. Similarly, swine challenged with a dose of 20 microg/kg also exhibited the greatest increase in levels of conjugated bilirubin; there was no effect on unconjugated (free) bilirubin. These results demonstrate that endotoxin challenge of swine result in a pattern of changes that are dependent on both the dose of endotoxin used and the metabolic status of the animal examined.

Estimates of genetic parameters for carcass measures of body composition and growth in swine.

Records for pigs included in an experiment on reciprocal recurrent selection conducted from 1956 through 1971 at the USDA Beltsville Agriculture Research Center were analyzed to obtain estimates of heritabilities and genetic correlations and to derive prediction equations for estimating weight of lean cuts (WTLC) and percentage of lean cuts of shrunk slaughter weight (LCPC). Lean cuts growth rate (LCGR) was then estimated as WTLC/age of pig at slaughter. The base population consisted of two unrelated crossbred strains. A total of 1,294 records of F1 and F2 crossbred pigs were analyzed with one barrow and one gilt from each litter. Estimates of heritabilities and genetic correlations were computed with sire components of variance and covariance from a nested analysis of variance with an assumed model of years, strain-lines within years, sire within strain-lines, dams within sires and residual. Degrees of freedom were 307 for sires in strain-lines, 270 for dams in sires and 646 for residual. Heritability (h2) estimates were .42 +/- .13, .41 +/- .13 and .27 +/- .18 for WTLC, LCPC and LCGR, respectively, and .71 +/- .16, .38 +/- .13, .31 +/- .13 and .25 +/- .15 for carcass length, average backfat thickness, longissimus muscle area and ADG in BW, respectively. These estimates were apparently the first published genetic estimates involving LCGR based on carcass data. It was recommended that prediction equations to estimate WTLC, LCPC and LCGR for use in swine testing programs be derived from current meat-type pigs.

Performance of Duroc and Yorkshire boars and gilts and reciprocal breed crosses.

Analyses of variance were computed for records on growth and body composition traits made in 1983 by 255 boars and gilts in selected and control lines of Durocs and Yorkshires and their reciprocal crossbreds. Previous selection over a period of several generations was mainly on an index of sow productivity including preweaning litter sizes and weight. Animals in the select lines were selected for high index values; animals in the control lines were selected to average near the mean index values of that year and line. Breeding animals in all four lines during that period were basically randomly selected with regard to growth rate or body composition traits. The same boars sired both purebred and crossbred litters in 1983. Traits analyzed were average daily gain (ADG) during a standard test period from 56 d of age to 90.7 kg and average backfat thickness (ABF) and longissimus muscle area (LMA) from ultrasonic scans at 90.7 kg. Crossbred pigs had greater (P less than .01) ADG than purebred pigs, but did not differ (P greater than .05) in ABF or LMA. Heterosis was 8.2% for ADG. Crossbreds with Yorkshire dams had thinner (P less than .01) ABF and larger (P less than .01) LMA than crossbreds with Duroc dams. Boars had greater (P less than .05) ADG, thinner (P less than .01) ABF and smaller (P less than .01) LMA than gilts. Correlations between 38 half-sib family averages of purebred and crossbred pigs of the same sex and the same sires were .07, .37 and .24 for ADG, ABF and LMA, respectively. Implications of the above and additional findings for swine breeding strategies are discussed.

Selection line x diet interactions for two lines of pigs fed 12 or 24% protein diets.

An experiment with crossbred swine was conducted over six generations of selection based on an index (Index) of average daily gain in weight (ADG) in a test period from 56 d of age to 91 kg gross weight and average backfat thickness (ABF) measured from ultrasonic scans at 91 kg. Test pigs of the high protein select (HS) and control (HC) lines were fed a 24% crude protein (CP) diet and pigs of the low protein select (LS) and control (LC) lines were fed a 12% CP diet during the test period. The extent of genetic (selection line) x environmental (dietary) interaction effects was determined based on feeding closely related boars and gilts from both the HS and LS lines on both diets. Tests were conducted in 1986 and 1987 with progeny of the fifth and sixth generations of selection. Records for 472 pigs sired by 37 boars and out of 101 dams were analyzed for effects of selection and diets on AGE of pig at 91 kg, ADG, ABF, LMA (longissimus muscle area at the last rib) and Index. Statistically significant interactions effects of line x diet were noted (P less than .01) for AGE, ADG and Index, traits with low to moderate heritabilities (h2). For ABF and LMA, body composition traits with moderate or higher h2, interaction effects of line x diet were near zero. These results suggest that for best all-around future performance, traits such as AGE and ADG, selection probably should be practiced under dietary conditions under which future populations will be produced. For body composition traits such as ABF and LMA, selection probably would be more effective if pigs were fed a more enriched protein diet. However, as a practical matter, to more rapidly improve the genetic merit of the swine population, both the central station and on-the-farm testing programs should be conducted under standard commercial production systems.

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: II. Accretion rates of protein, collagen, and fat.

The present study was conducted to determine the effects of different dietary protein levels and recombinant porcine somatotropin (rpST) administration on deposition rates of protein, fat, water, ash, and collagen in pigs. Ten groups of six barrows (30 kg BW) were restrictively fed (80% of ad libitum) one of five diets containing 11, 15, 19, 23, or 27% CP. Diets were isoenergetic and all contained equivalent amounts of lysine. Thirty barrows were treated daily with rpST (100 micrograms/kg) by i.m. injection; remaining pigs were treated with diluent for 42 d. At all levels of dietary protein intake, carcass and empty body accretion rates of protein, water, and ash were greater in rpST-treated pigs than in respective controls. The magnitude of change elicited by rpST was lowest in pigs consuming 11% CP. Administration of rpST resulted in a 34% decrease in the accretion rate of fat; increasing protein intake resulted in a linear decrease in fat accretion in control and rpST-treated pigs. Accretion rates of protein, water, ash, and fat were increased in viscera of rpST-treated pigs compared with respective controls; rates of visceral protein and water accretion were increased as dietary protein was increased, whereas deposition of fat was decreased in control and rpST-treated pigs. Administration of rpST resulted in an overall 66% increase in the utilization efficiency of dietary protein for empty body protein deposition. Protein intake had minimal effect on the concentration of collagen in the carcass; however, rpST treatment increased concentrations of total and soluble collagen by 30 and 33%, respectively. Recombinant pST had little influence on collagen crosslinking or maturation. Deposition rate of carcass collagen was increased 63% in rpST-treated pigs compared with respective controls.

Endocrine adaptations of periparturient swine to alteration of dietary energy source.

Lipid compared with carbohydrate calories in the diet of peripartal sows was examined for specific metabolic effects. Blood samples from second-parity Yorkshire sows fed isocaloric-isonitrogenous diets that differed by either glucose or corn oil supplying 20% of the daily metabolizable energy intake were assayed for growth hormone (GH), insulin and prolactin (PRL) concentrations. On d 97 to 103 of gestation, serum GH levels were reduced following feed intake; the reduction was greater (P less than .05) in glucose-fed sows during the postprandial period. Insulin concentration was increased following consumption of either diet, but to a greater (P less than .05) extent in glucose-fed sows corresponding to the greater (P less than .05) blood glucose response. Basal, fasting concentrations of PRL were not affected by dietary energy source; however, thyrotropin-releasing hormone (TRH) infusion resulted in a greater (P less than .05) PRL response of fat-fed sows. Samples obtained on d 8 to 11 of lactation revealed that TRH stimulated (P less than .05) GH secretion and the response was greater (P less than .05) in fat-fed sows. Plasma insulin concentration was increased (P less than .05) following feeding, and the increase was greater (P less than .05) in glucose-fed sows. Similar to the response measured in gestating sows, TRH-induced increases in PRL was greater in fat-fed, lactating sows. Sham-nursing did not influence maternal PRL concentration compared with the immediate increase noted following natural nursing. No effect of dietary energy source on reproductive performance characteristics was noted. Results of this study have shown that dietary lipid, compared with carbohydrate, selectively increased the sensitivity of the pituitary gland to a GH and PRL secretagogue such as TRH. The beneficial effects of lipid in the diet of peripartal swine may be attributable, in part, to the effect of dietary lipid on maternal pituitary PRL synthesis and(or) release.

Effect of sex and exogenous porcine somatotropin on longissimus muscle fiber characteristics of growing pigs.

Thirty-seven pigs with an initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine somatotropin (pST) administration at two dose levels (0 and 100 micrograms.kg-1.d-1) for a 31-d period on muscle fiber characteristics and meat tenderness of boars, gilts and barrows. Excipient boars and gilts had more alpha W and fewer alpha R fibers than did those receiving pST. The percentage of muscle fiber type for barrows was not affected by pST treatment. The administration of pST resulted in an increase in muscle fiber size for all three fiber types in all three sexes, but these changes were of greater magnitude in barrows (31.8%) and gilts (27.8%) than in boars (9.3%). Somatotropin negated the intrinsic sex effect differences in fiber area of the pigs. There was no difference in tenderness among excipient boars, barrows and gilts; however, with the inclusion of pST, shear force decreased in boars and gilts and increased in barrows. A high proportion of the pST-treated pigs contained giant fibers in the longissimus muscle. Furthermore, a small proportion of the pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomalies occurred through increased muscle activity or from fibers undergoing degenerative changes was not determined.

Influence of level of dietary protein or energy on effects of ractopamine in finishing swine.

The effect of ractopamine, a beta-adrenergic agonist, on growth, nutrient utilization, and carcass composition was studied in pigs fed either 18% CP, 12% CP, or 18% CP restricted (RES = 67% of ad libitum) diets. The 18 and 12% CP diets provided 3.52 and 3.68 Mcal of DE/kg, respectively. All pigs were fed a low-protein (12% CP) diet during pretreatment growth from 15 to 60 kg. Ractopamine at 20 or 30 ppm (30 ppm for RES pigs) in the diet was fed from 60 kg live BW until slaughter at 105 kg (9 pigs/treatment). No ractopamine treatment effect (P greater than .05) was observed for either daily gain or gain/feed, although gain/feed was improved by 8% in both of the ad libitum groups. Ractopamine treatment resulted (P less than .01) in an overall reduction of carcass lipid by 8%, an increase of carcass protein by 5%, and a 21% improvement in the efficiency of protein utilization; the greatest changes occurred in the pigs fed the 12% CP diet (-17%, +11%, and +32%, respectively). The ad libitum daily feed intake was 15% less for pigs fed the 12% CP diet than for those fed the 18% CP diet (P less than .01), and there was a 10% reduction in intake of both diets with the addition of ractopamine (P less than .05). Both carcass lipid and protein deposition seemed to be closely related to energy intake (P less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Interrelationships of exogenous porcine growth hormone administration and feed intake level affecting various tissue levels of iron, copper, zinc and bone calcium of growing pigs.

Trace mineral status was evaluated in a 2 x 3 factorial treatment array with a total of 34 barrows growing from 25 to 55 kg live weight. Treatments included three levels of feed intake (100, 80 and 60% of ad libitum intake) and exogenous pituitary growth hormone (pGH) therapy (0 and 100 micrograms/kg BW daily). Blood was collected prior to slaughter for the determination of hematocrit and serum trace metal concentrations; tissues (liver, heart, kidney, bone and muscle) were obtained when pigs were slaughtered at 55 kg. Hematocrits and serum Fe were lower in pGH-treated pigs than in controls at all levels of feed intake. Serum Cu was increased by feed restriction but was not altered by pGH therapy. The concentration of serum Zn was not affected by either treatment. Concentrations of hepatic Fe and Cu were lower in pGH-treated pigs than in controls but were higher in feed-restricted pigs than in ad libitum-fed pigs. However, the total amounts of hepatic Fe and Cu were similar in pGH-treated pigs to concentrations in controls. The concentration of hepatic Zn was not influenced by either pGH treatment or feed intake. Femur weights were marginally greater in pGH-treated pigs, probably due to elevated water content. Iron concentration in bone was higher in pGH-treated pigs than in control pigs, whereas Ca, Cu and Zn were not influenced by pGH treatment or feed restriction. Feed intake and pGH treatment did not influence the concentrations of Fe, Cu or Zn in muscle. These findings indicate that pGH therapy affects the metabolism of Fe but has little impact on the overall composition of body ash.

Influence of helminth parasite exposure and strategic application of anthelmintics on the development of immunity and growth of swine.

Infection of pigs with the intestinal roundworm parasite Ascaris suum and strategic application of anthelmintic drugs during the growing phase of development were observed for specific effects on 1) development of immunity in feeder pigs and 2) growth rate during the finishing phase. Management treatments included maintenance in a parasite-free concrete environment, maintenance in a concrete environment and inoculation with 1,000 infective A. suum eggs every other day over a 52-d period, and maintenance on a dirtlot contaminated with A. suum and Trichuris suis eggs. Within each management environment, pigs were either untreated, treated with ivermectin or treated with fenbenzadole at strategic times during parasite exposure. Protective immunity, assessed by a challenge inoculation with A. suum eggs following management treatments, was not affected by ivermectin or fenbenzadole treatment during exposure, but adult worm burdens were reduced and the pattern of A. suum larval antigen serum antibody responses were different from those in control pigs not treated with drugs. Exposure to A. suum and treatment with anthelmintics during the growing phase reduced adult worm burdens following the finishing phase of growth. Rate, but not efficiency, of gain was significantly improved by anthelmintic treatment following natural exposure to parasites. Strategic treatment of pigs with anthelmintics following inoculation with A. suum eggs in a concrete management environment had no effect on rate of gain. Results suggest that natural exposure to parasites during the growing phase without therapeutic treatment causes permanent damage to growth potential.

Response of low and high protein select lines of pigs to the feeding of the beta-adrenergic agonist ractopamine (phenethanolamine).

The effect of ractopamine, a phenethanolamine beta-adrenergic agonist, on growth, nutrient utilization and carcass composition was studied in two lines of pigs that were fed high (24%) or low (12%) protein diets. Of the two lines of pigs that had been selected for seven generations for rapid lean growth when fed either the higher (HS line) or low (LS line) protein diet, the HS line tended to exhibit a leaner carcass when fed either diet. Ractopamine, at 20 ppm in the diet, was fed from 60 kg live body weight until slaughter at 90 kg. When compared with their respective line-diet control group, the greatest response to ractopamine treatment was observed in the LS-12 group; at 90 kg, that group had 31% less carcass lipid (P less than .05) and 17% more carcass protein (P less than .05). Considering the change that took place only between 60 and 90 kg live body weight, this translated into 57% less lipid and 59% more protein deposited in the carcasses with ractopamine treatment. This group also was 73% more efficient (P less than .05) in converting dietary protein to carcass protein but 39% less efficient (P less than .05) in energy utilization. Response to ractopamine treatment was least by the LS-24 group, followed by the HS-12 and HS-24 groups. A line x diet x treatment interaction (P less than .05) was noted for whole-carcass lipid, backfat, longissimus muscle area and efficiency of protein utilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of an endotoxin challenge on growth performance, carcass accretion rates, and serum hormone and metabolite concentrations in control pigs and those treated with recombinant porcine somatotropin.

Barrows were restrictively fed starting at 20 kg BW to determine the effects of endotoxin on growth performance of control and somatotropin-treated pigs. The following treatments were used: 1) daily i.m. vehicle injection until 55 kg BW; 2) daily i.m. injections of 100 micrograms of recombinant porcine somatotropin (pST)/kg BW, until 55 kg; 3) i.v. saline injections for 7 d consecutively starting at 60 kg BW; 4) i.v. injections of 1 microgram of bacterial lipopolysaccharide (LPS)/kg BW for 7 d starting at 60 kg BW; and 5) the combined LPS+pST treatment, with pST injections from 20 kg through the 7 d of LPS treatment. Pigs evaluated for LPS effects were fed to 60 kg anticipating a weight loss. Pigs were bled at 0800 and 1100 at 55 kg and on d 7 of LPS treatment. Rectal temperatures were taken on d 7. Treatment with pST increased ADG by 13 to 20% and improved feed:gain by 17 to 23% before LPS treatment. During the 7 d of LPS injections, ADG and feed:gain did not differ, although feed efficiency was impaired and variable. Rectal temperatures at 1100 were progressively increased: control < LPS < LPS-pST (P < .01). Protein accretion was improved 27% by pST treatment, and lipid accretion was decreased 45% before LPS. Lipid stores decreased (P < .01) after LPS treatment in the pST-treated pigs. Lipopolysaccharide treatment and(or) decreased feed intake reduced the hyperinsulinemia and hyperglycemia (P < .01) associated with pST treatment. These results indicate that LPS induced a simulated septicemia and that the effects were not negated by pST treatment. The observed hyperthermia was additive, possibly due to increased lean body mass induced by pST combined with the pyrogenic effect of LPS.

Digestibility of fiber components and reproductive performance of sows fed high levels of alfalfa meal.

Two experiments were conducted with second-parity sows fed either 5 or 50% alfalfa meal diets (Exp. 1) or 5, 50 or 95% alfalfa meal diets (Exp. 2) beginning 30 d after breeding and continuing through lactation, 21 d postpartum. Diets in both experiments were calculated to be equal in crude protein, but different in metabolizable energy content. Feed intake was restricted to 2 kg/d during gestation and ad libitum during lactation. Sows were tethered in metabolism crates 45 d after breeding. Total feces were collected during two 5-d collection periods, 60 and 100 d after breeding. Digestibilities of dry matter, fiber components (neutral detergent fiber, acid detergent fiber, hemicellulose and cellulose), protein and energy were determined in both experiments for all diets and periods of gestation. In both experiments, there was a reduction (P less than .05) in digestibility of dry matter, fiber components, protein and energy with increasing fiber levels for both periods of gestation. In Exp. 1, the decrease in digestibility of dry matter, neutral detergent fiber, acid detergent fiber, cellulose and energy was greater at 100 d gestation than at 60 d in sows fed 50% alfalfa. In Exp. 2, 50 and 95% dietary alfalfa reduced 60-d digestibilities of dry matter, all fiber constituents, energy and protein; these digestibilities were further reduced (P less than .05) at 100 d of gestation. In Exp. 1, weight gains of sows fed 5 and 50% alfalfa diets from breeding to 109 d gestation, were 42 and 18 kg/sow (5 greater than 50% level, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal hepatic and neural substrate utilization as affected by induced nutritional ketosis in swine.

Systemic ketosis was induced in first-parity gilts by the isocaloric substitution of glucose with 1,3-butylene glycol to supply 20% of the total dietary energy beginning on d 23 (23 BG) or d 60 (60 BG) of gestation. Ketosis reduced (P less than .05) maternal plasma glucose, urea N and insulin concentrations. Fetal carcass dry matter and carcass glycogen contents were reduced (P less than .05) by maternal ketogenic calorie substitution, whereas fetal hepatic glycogen and lipid contents were not influenced by maternal treatment. Neural acetate oxidation was reduced (P less than .05) in the 23 BG and 60 BG fetuses, with a concurrent increase (P less than .05) in beta-hydroxybutyrate (BOHB) oxidation. Neural lipogenesis measured from acetate and BOHB substrates was nominal in the d 105 pig fetus. Fetal hepatic acetate and BOHB utilization for lipogenesis were increased (P less than .05) by maternal ketosis. Reproductive performance characteristics (litter size, number stillborn and birth weight) were not improved by maternal ketosis. The substantial improvement in lactation weight gain by litters from 23 BG and 60 BG dams (20%, P less than .05) may suggest a carryover effect of gestation dietary treatment on lactation performance.

Influence of time of injection of recombinant porcine somatotropin (rpST) relative to time of feeding on growth performance, hormone and metabolite status, and muscle RNA, DNA, and protein in pigs.

Thirty-six barrows were used in a 2 X 3 factorial treatment array to determine the effects of time of injection (0800 [AM] or 1800 [PM]) of recombinant porcine somatotropin (rpST) (0, 50, or 100 micrograms.kg BW.d-1 adjusted weekly) relative to time of feeding on growth performance, carcass composition, serum hormones and metabolites, and muscle RNA, DNA, and protein. Pigs were fed at 85% of ad libitum and allowed access to feed between 0800 and 1200. Treatments were initiated at 38 kg and continued until each pig consumed an average of 7.5 Mcal of DE/d. There was no significant effect of injection time for any measure of growth performance or composition of gain even though rpST treatment improved most criteria evaluated. Treatment with rpST increased ADG by 30%, improved feed:gain by 23%, reduced lipid accretion by 46%, increased protein accretion by 69%, and increased loin eye area (LEA) by 26%. Time of injection also had no effect on serum hormones or metabolites, except for nonesterified fatty acids (NEFA), which were 20% higher in the AM-injected animals. Treatment with rpST increased (P less than .05) RNA concentration (21%) and RNA/DNA (17%) in longissimus dorsi (LD) muscle. In semimembranosus (SM) muscle, however, rpST administration resulted in an increased (P less than .05) DNA concentration (10%) and a decreased DM content (4%). These results suggest that rpST influences growth differently in these two muscles. We conclude that time of rpST administration (AM vs PM) has no effect on its metabolic properties and, therefore, no effect on growth performance in the pig.