Biomedical subjects

T J Caperna

Publications and source records attributed to T J Caperna.

At least 37 records · Page 2Linked to original sources

PubMed1994

A continuous culture of pluripotent fetal hepatocytes derived from the 8-day epiblast of the pig.

Continuous cultures of pluripotent parenchymal hepatocytes were derived from the epiblasts of 8-day-old pig blastocysts. The cells were polygonal and had phase-contrast dark, granular cytoplasm with prominent nuclei and nucleoli. These feeder-dependent cell cultures differentiated into large, multicellular, secretory, duct-like structures or formed small canaliculi between individual cells. Alternatively, the cells accumulated droplets that stained intensely with Oil Red O, a lipid-specific stain. Alpha-fetoprotein (AFP), albumin, and beta-fibrinogen mRNAs were expressed as the cells differentiated in culture. Serum-free medium that was conditioned by the cells contained transferrin, AFP, and albumin. The growth and viability of the cells were inhibited by transforming growth factor beta 1 (TGF beta 1) at concentrations > or = 1 ng/ml. The cell cultures grew slowly with doubling times of 2 to 3 d. One of the cultures, pig inner cell mass-19 (PICM-19), was passaged continuously for over 2 yr [> 100 population doublings (PD)] and appears to be an infinitely self-renewing cell population. The stem cell characteristics of the epiblast-derived fetal hepatocytes indicate that the cells may be unique for investigations of liver differentiation and organogenesis.

Animals↗

PubMed1994

Colony isolation and secondary culture of fetal porcine hepatocytes on STO feeder cells.

The secondary culture of non-transformed parenchymal hepatocytes has not been possible. STO feeder cell-dependent secondary cultures of fetal pig hepatocytes were established by colony isolation from primary cultures of 26-d fetal livers. The liver cells had the typical polygonal morphology of parenchymal hepatocytes. They also spontaneously differentiated to form small biliary canaliculi between individual cells or progressed further to large multicellular duct-like structures or cells undergoing gross lipid accumulation and secretion. The secondary hepatocyte cultures expressed alpha-fetoprotein (AFP), albumin, and beta-fibrinogen mRNA, and conditioned medium from the cells contained elevated levels of transferrin and albumin. STO feeder cell co-culture may be useful for the sustainable culture of hepatocytes from other species.

Animals↗

PubMed1994

Somatotropin alters collagen metabolism in growing pigs.

Treatment of pigs with porcine somatotropin (pST) is associated with altered nutrient partitioning. The aim of this investigation was to determine the role of pST in protein and collagen deposition in growing pigs. Barrows were treated daily with buffer or pST when they weighed between 30 and 64 kg (n = 8 pigs/group). Pigs were restrictively fed such that the average feed intake for both groups was 1.86 kg/d. Treatment with pST was associated with 25, 55, 78 and 31% higher growth rates for carcass, skin, viscera and head, respectively. Total protein depositions (g/d) were 52, 60, 81, 42 and 54% greater in carcass, skin, viscera, head and empty body, respectively, of pST-treated pigs. Collagen represented approximately 70, 15 and 43% of total protein in skin, viscera and head; pST did not influence this ratio. However, collagen relative to total protein was 16% lower in the carcass of pST-treated pigs. Deposition rate of collagen was higher in all components of empty body, except carcass, as a result of pST treatment. The ratio of non-collagen protein to collagen deposition rate was 49% greater in the carcass of pST-treated pigs. The deposition rate of acid-soluble collagen was approximately 2-fold higher in skin but was 25% lower in carcass of pST-treated pigs. Depositions of insoluble collagen in viscera and head of pST-treated pigs were 74 and 46% greater, respectively, than for controls. These data show that pST treatment enhances collagen deposition in skin, head and viscera, whereas non-collagen protein deposition and collagen maturation are enhanced in the carcass.

Administration, Oral↗

PubMed1994

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: III. Muscle fiber morphology and shear force.

Sixty crossbred barrows (average 30 kg) were used in a 5 x 2 factorial treatment array to examine interactions between dietary protein concentration (11, 15, 19, 23, or 27% CP) and recombinant porcine somatotropin (rpST: 0, excipient buffer vs 100 micrograms.kg-1.d-1) for 42 d on muscle fiber morphology and meat tenderness. Diets were isocaloric (3.8 Mcal of DE/kg) and of equal lysine (4.9 g/Mcal of DE) achieved by diluting soybean meal with cornstarch and by addition of crystalline lysine. Dosage of rpST and feed intake (80% of predicted ad libitum) were adjusted weekly. Four muscles (longissimus = LM; semimembranosus = SM; semitendinosus = ST; triceps brachii = TB) were evaluated. Percentages of muscle fiber types (beta R, alpha R, alpha W) for the LM, SM, and TB were not influenced by rpST treatment. More alpha R and fewer alpha W fibers were found in the ST muscle of rpST-treated pigs. No interactions were observed between rpST treatment and dietary protein for muscle fiber type distribution. Dietary protein had no consistent influence on the distribution of muscle fiber types in all four muscles. Area of fibers generally increased in rpST-treated pigs compared with controls when diets contained 19% or more CP. The LM shear force was increased (13%) by rpST treatment for chops frozen after 5 d of storage in the cooler, but not in those chops frozen within 1.5 h postmortem. Dietary protein had a variable influence on tenderness. These data indicate that muscle fiber growth (hypertrophy) in pigs is positively influenced by rpST treatment. Marginal dietary protein intake reduces muscle fiber growth responses to rpST.

Animals↗

PubMed1993

Acute effects of administration of porcine growth hormone on circulating levels of hormones and metabolites in 20-, 40-, and 60-kilogram gilts.

Three groups of eight gilts weighing 20, 40, or 60 kg were fitted with indwelling venous catheters to determine daily integrated circulating levels (DICL, serum concentration above baseline x time) of insulin, growth hormone (GH), glucagon, glucose, urea, and nonesterified fatty acids (NEFA) in response to acute challenge with porcine pituitary GH (pGH). Pigs were fed a common diet containing 18% CP and 3.5 Mcal of DE/kg between 0800 and 1200 (85% of ad libitum). Blood and urine were collected at 2- or 4-h intervals for 4 d. On d 2, 3, and 4, four pigs in each group were injected i.m. at 0800 with pGH (.1 mg/kg) and four pigs (controls) were injected with buffer. In control pigs DICL of GH was 20.4, 14.1, and 10.2 ng pGH.h.mL-1 in 20-, 40-, and 60-kg pigs, respectively. The DICL of GH in pGH-treated pigs was 4.2-, 7.0-, and 10.7-fold greater in 20-, 40-, and 60-kg pigs, respectively, than in controls. The DICL of insulin in control pigs was 7.9, 9.7, and 9.4 ng.h.mL-1 and was increased (P < .001) in pGH-treated pigs by 118, 213, and 276% in 20-, 40-, and 60-kg pigs, respectively. Although serum levels of glucose were increased (P < .001) by pGH treatment, the acute elevation observed in 60-kg pigs was more consistent relative to 20- and 40-kg pigs. In contrast, the acute reduction in blood urea upon pGH injection was more apparent in 20-kg gilts.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Effects of frequency of recombinant porcine somatotropin administration on growth performance, tissue accretion rates, and hormone and metabolite concentrations in pigs.

Thirty-two crossbred barrows were used to determine the effects of frequency of administration of equivalent total dosages of recombinant porcine somatotropin (rpST) on growth performance, tissue accretion rates, and hormone and metabolite status of pigs. Treatments were control (buffer-injected daily), 60 micrograms/kg BW daily (4 injections/4 d), 120 micrograms/kg BW injected every other day (2 injections/4 d), or 240 micrograms/kg BW given every 4th d (1 injection/4 d). Treatments were initiated at 35 BW and continued until each pig had consumed a total of 440 Mcal of DE intake. Pigs were fed a diet that contained 16% CP, 1.2% lysine, and 3.5 Mcal of DE/kg at 85% of calculated ad libitum intake. Feed intake and rpST dose were adjusted at 8-d intervals. The 240 micrograms/kg BW treatment did not decrease appetite beyond the 15% restriction already imposed in the experimental design. Treatment groups responded to rpST in a frequency-dependent manner. Average daily gain was improved by 10, 23, and 36%, respectively, as injection frequency was increased from 1/4 to 2/4 to 4/4 d. Muscle weights were increased uniformly (15% on average) on a BW basis by all rpST treatments. Carcass (21, 42, and 63%), visceral (43, 65, and 112%), and empty body (22, 43, and 65%) protein accretion rates were increased by rpST treatment in a frequency-dependent fashion, respectively. Lipid accretion also was reduced in carcass and empty body (31% on average) by all rpST injection schemes relative to controls; however, visceral lipid accretion was increased by 59% by rpST. Protein utilization efficiency increased linearly by 24, 45, and 65% as the frequency of injection of rpST was increased from 1/4 to 2/4 to 4/4 d. Hormones and metabolites exhibited frequency-related profiles as well. These results suggest that frequency of administration greatly influences the magnitude of responsiveness to rpST and that optimal benefit would be realized by a delivery system that mimicked a daily surge, at minimum, of rpST.

Adipose Tissue↗

PubMed1991

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.

Adipose Tissue↗

PubMed1991

Effects of exogenous porcine somatotropin administration between 30 and 60 kilograms on longissimus muscle fiber morphology and meat tenderness of pigs grown to 90 kilograms.

Twenty-four barrows were used to investigate the effects of exogenous porcine somatotropin (pST) administration (0 and 100 micrograms.kg-1.d-1) between 30 and 60 kg on longissimus muscle morphology and meat tenderness of pigs grown to 90 kg. Administration of pST was by daily i.m. injection. Pigs were fed a fortified diet in restricted amounts between 30 and 60 kg and had ad libitum access to this diet from 60 to 90 kg. Excipient pigs had fewer alpha R fibers and more alpha W fibers than pST-treated pigs (P less than .05). Administration of pST increased (P less than .05) muscle fiber area for all three fiber types at both the 60 kg (34%) and 90 kg (29%) slaughter weights. Furthermore, pST administration increased shear-force (30% at 60 kg; 19% at 90 kg) of the longissimus muscle, indicating that pST administration reduced meat tenderness. All the pST-treated pigs exhibited the "giant fiber syndrome" and a high proportion (62%) of pST-treated pigs exhibited pale, soft, exudative muscle. Whether the giant fiber anomaly resulted from increased muscle protein accretion rate or fiber degeneration is unknown. Results indicated that the stimulatory effects of pST on muscle growth are sustained following cessation of hormone treatment. However, the incidence of pale, soft, exudative muscle in 62% of the pST-treated pigs indicates that pST potentially has undesirable side effects.

Animals↗

PubMed1991

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.

Adipose Tissue↗

PubMed1991

Tumor necrosis factor-alpha affects growth hormone secretion by a direct pituitary interaction.

Administration of 50, 250, and 1,250 ng/kg iv of recombinant bovine tumor necrosis factor-alpha (RBTNF) did not affect basal plasma concentrations of growth hormone (GH) or thyroid-stimulating hormone in male calves. However, when administered 30 min before challenge with 1 microgram/kg iv of thyrotropin-releasing hormone (TRH), 250 ng/kg of RBTNF increased the subsequent incremental GH response. At 1,250 ng/kg of RBTNF, GH response to TRH was significantly blunted. For each dose of RBTNF administered, the incremental change in plasma thyroid-stimulating hormone following TRH was not significantly different from control. To examine direct effects of RBTNF on pituitary function, fresh bovine pituitaries were sliced into 1-mm cubes and incubated with 0 or 10(-8), 10(-9), or 10(-10) M RBTNF. Additional cultures were treated with 10(-8) or 10(-9) M GH-releasing factor or 10(-8) M TRH and 0 or 10(-8) M RBTNF. Media GH increased in cultures with 10(-10) M RBTNF and declined linearly as RBTNF concentration increased. RBTNF blocked GH release from GH-releasing factor- and TRH-challenged pituitary slices. Membranes prepared from homogenized bovine pituitaries had specific saturable binding characteristics for monomeric 125I-RBTNF. Membranes treated with 4 M MgCl2 for 10 min and washed free of Mg2+ produced Scatchard plots fit to a two-site model (high affinity site Kd = 6.6 nM), while Scatchards of non-Mg(2+)-treated membranes fit a single site (Kd = 8.9 nM). Polyacrylamide gel electrophoresis separation of 125I-RBTNF cross-linked pituitary membranes showed specific binding of monomeric 125I-RBTNF to protein components ranging in molecular weight from 19,000 to 77,000. The data suggest that RBTNF has modulatory effects on the regulation of GH secretion acting directly at the pituitary through specific receptors.

Analysis of Variance↗

PubMed1990

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)

Animals↗

PubMed1990

Influence of dietary protein and recombinant porcine somatotropin administration in young pigs: growth, body composition and hormone status.

The influence of dietary protein and recombinant porcine somatotropin (rpST) administration on growth and body composition was investigated in barrows. Ten groups of six pigs starting at 30 kg were restrictively fed (approximately 80% of ad libitum) one of five diets containing 11, 15, 19, 23 or 27% protein. Diets contained skim milk (12%). Soybean meal diluted with cornstarch was used as the supplemental source of dietary protein. Diets were isocaloric (3.8 Mcal DE/kg) and all contained the same amount of lysine (18 to 20 g/kg). Thirty pigs were treated daily with rpST (100 micrograms/kg) by i.m. injection; the remaining pigs were treated with sterile diluent (control) for 42 d. Growth rate was greater in rpST-treated pigs at all levels of protein intake; however, the magnitude of the response to rpST treatment was lowest among pigs fed the diet containing 11% protein. Feed:gain ratio, backfat depth and carcass fat content were decreased in rpST-treated pigs compared to respective controls. Additionally, the concentration of carcass fat decreased concomitantly with an increase in dietary protein intake. Concentration of carcass protein increased linearly as dietary protein increased in control and rpST-treated pigs. In contrast, treatment with rpST was associated with an increased visceral mass; the concentration of protein and fat in the viscera was influenced by protein intake but not by rpST. These results, characterized by few treatment interactions, suggest that when energy intake is kept constant and appropriately fed pigs serve as controls, dietary protein and rpST influence growth and body composition by independent mechanisms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1989

Interrelationships between sex and exogenous growth hormone administration on performance, body composition and protein and fat accretion of growing pigs.

Forty-five pigs with an average initial live weight of 60 kg were used to investigate the effects of daily exogenous porcine pituitary growth hormone administration at two dose levels (pGH; 0, excipient buffer injected, and 100 micrograms.kg-1.d-1) for a 31-d period on the performance and body composition of boars, gilts and barrows allowed to consume feed ad libitum. Excipient boars consumed less feed, exhibited faster and more efficient growth (P less than .01) and produced less fat and more protein and water (P less than .01) in the empty body compared with excipient barrows, which in turn contained more fat and less water (P less than .05) in the empty body than did excipient gilts. These differences were largely eliminated by pGH administration, which induced differential effects in growth performance and body composition in boars, gilts and barrows. Growth hormone administration improved growth rate by 13, 22 and 16% and feed conversion efficiency by 19, 34 and 32% in boars, gilts and barrows, respectively. The reduction of body fat content (g/kg) elicited by pGH was 22, 36 and 33% for boars, gilts and barrows, respectively, with a corresponding increase (P less than .01) of body protein and water content. The magnitude of the pGH responses was greatest for gilts and barrows compared with boars, negating intrinsic sex-effect differences in growth performance and body composition of pigs. Pigs used in this study and treated with pGH exhibited a rate of protein deposition (approximately 225 g/d) far greater than previously reported, and as such redefine the genetic capacity for lean tissue growth by the pig.

Adipose Tissue↗

PubMed1989

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.

Animal Feed↗

PubMed1989

Effects of exogenous porcine growth hormone administration between 30 and 60 kilograms on the subsequent and overall performance of pigs grown to 90 kilograms.

Twenty-eight barrows were used to investigate the effects of exogenous porcine growth hormone (pGH) administration (0 and 100 micrograms.kg-1.d-1) between 30 and 60 kg on the subsequent and overall performance and carcass composition of pigs grown to 90 kg. The pGH was administered by daily i.m. injection and all pigs were fed one diet. Control animals were pair-fed to the intake noted for pGH-treated pigs between 30 and 60 kg and all pigs were fed ad libitum from 60 to 90 kg. Pigs administered pGH had an improved rate (36%) and efficiency (28%) of gain and an improved protein accretion rate (46%) compared to excipient-treated pigs. Pigs previously treated with pGH continued to exhibit superior (P less than .01) rate and efficiency of gain, and the gain was associated with enhanced protein accretion during the quiescent (postinjection) period compared with excipient counterparts. Administration of pGH between 30 and 60 kg reduced carcass fat and increased carcass protein and water at 90 kg, although fat accretion rate was comparable to that of control pigs. Results indicate that, to varying degrees, the stimulatory effects of pGH on growth performance are sustained following cessation of hormone treatment.

Animals↗

PubMed1988

Effect of feed intake and exogenous porcine somatotropin on longissimus muscle fiber characteristics of pigs weighing 55 kilograms live weight.

Thirty two barrows were used in a 2 x 3 factorial arrangement to evaluate the effects of porcine somatotropin (pST) administration (USDA-pGH-B1; 0 and 100 micrograms.kg BW-1.d-1) and feed intake (FI; ad libitum [A], 1.64 [R1:80% of A] and 1.38 [R2:60% of A] kg/d) on longissimus (LM) muscle fiber characteristics of pigs growing from 25 to 55 kg live weight. The administration of pST resulted in an increase (P less than .05) in muscle fiber size (all three fiber types) and shear-force (17.1%). The percentage of muscle fiber types was not affected by pST treatment. Feeding of the diet at restricted levels (R1 and R2) resulted in smaller (P less than .05) beta R and alpha W fibers compared with feeding ad libitum. Pigs with ad libitum access to their diet had fewer alpha R fibers and more alpha W fibers in the LM compared with those fed at R1 and R2 levels. Restricted feed intake (R1 and R2) resulted in lower (P less than .05) shear-force values compared with ad libitum feeding. The present study indicates that pST administration of young barrows results in an increase in muscle hypertrophy. Restricted FI reduces both transformation from alpha R to alpha W fibers and muscle fiber hypertrophy.

Animals↗

PubMed1988

Interrelationships between energy intake and endogenous porcine growth hormone administration on the performance, body composition and protein and energy metabolism of growing pigs weighing 25 to 55 kilograms live weight.

Thirty-six barrows were used in a 2 X 3 factorial experiment to investigate the effects of porcine growth hormone (pGH) administration (USDA-pGH-B1; 0 and 100 micrograms.kg body weight-1.d-1) and three levels of feeding of a single diet (EI; ad libitum, 1.64 and 1.38 kg/d) on the performance, body composition and rates of protein and fat deposition of pigs growing over the live weight phase 25 to 55 kg. Raising EI resulted in linear increases in growth rate and in protein and fat accretion but had no effect on the feed to gain ratio (F/G). Carcass fat content and carcass fat measurements also increased with EI, whereas carcass protein and water decreased (P less than .01). Growth hormone administration resulted in improvements in growth rate (16 to 26%), F/G (23%), protein deposition (34 to 50%) and increases in carcass protein and water at each level of feeding, but reduced ad libitum feed intake (P less than .01), carcass fat content (P less than .01) and carcass fat measurements (P less than .01). Estimated maintenance energy expenditure was increased by pGH administration (2.02 vs 1.72 Mcal digestible energy/d). Results indicate that the effects of pGH on growth performance and energy and protein metabolism were largely independent of, and additive to, the effects of energy intake.

Animals↗

PubMed1987

Accumulation and metabolism of iron-dextran by hepatocytes, Kupffer cells and endothelial cells in the neonatal pig liver.

Treatment of newborn pigs with supplemental iron is a common procedure utilized to prevent neonatal anemia. The aim of this study was to investigate the hepatic distribution and intracellular metabolism of iron-dextran, a widely used colloidal-iron-carbohydrate preparation. Piglets were injected intramuscularly with iron-dextran (50 mg Fe/kg body wt) at 1 d of age. Hepatocytes and sinusoidal cells (Kupffer cells and endothelial cells) were isolated from iron-treated and control (uninjected) piglets at 2, 6 and 11 d of age. The concentrations of iron, copper and zinc in isolated cells were determined by atomic-absorption spectroscopy. In addition, the quantities of ferritin-protein and ferritin-iron were measured by immunoelectrophoresis and ion-exchange chromatography, respectively. At 2 d of age, the concentration (microgram/mg cell protein) of iron was 5-, 62- and 54-fold higher in hepatocytes, Kupffer cells and endothelial cells, respectively, isolated from iron-treated piglets than from control piglets. Hepatocytes, Kupffer cells and endothelial cells accumulated ferritin in response to iron-dextran treatment. Higher concentrations of ferritin-protein and ferritin-iron were present in Kupffer cells and endothelial cells than in hepatocytes at all times after treatment with iron-dextran. The percentage of cellular iron that was associated with ferritin, however, was greater in hepatocytes than in sinusoidal cells. Iron accumulated by all three liver cell types was mobilized to extrahepatic sites. Slight alterations in zinc and copper status of liver cells were evident at 11 d of age as a result of iron treatment.

Animals↗