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We conducted three experiments to determine the effects of increasing L-lysine HCl in growing-finishing pig diets. Experiments 1 and 2, conducted at the Kansas State University research center, each used 360 growing-finishing pigs with initial BW of 56 and 63 kg, respectively. Dietary treatments were sorghum- (Exp. 1) or corn- (Exp. 2) soybean meal-based and consisted of a control (no L-lysine HCl) or 0.15, 0.225, and 0.30% L-lysine HCl replacing lysine provided by soybean meal. Experiment 3 was conducted in a commercial research facility using a total of 1,200 gilts with an initial BW of 29 kg. Pigs were allotted to one of eight dietary treatments fed in four phases. These consisted of a positive control diet with no added L-lysine HCl and the control diet with 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30% L-lysine HCl replacing the lysine PrOvided by soybean meal. The eighth dietary treatment was a negative control diet with no added L-lysine HCl and formulated to contain 0.10% less total lysine than the other treatments to ensure that dietary lysine was not above required levels. In Exp. 1, increasing L-lysine HCl decreased (linear, P < 0.01) ADG, feed efficiency (G:F), and percentage lean and increased (linear, P < 0.01) backfat depth. In Exp. 2, increasing L-lysine HCl decreased (quadratic, P < 0.03) ADG, G:F, and ADFI, but carcass characteristics were not affected. In Exp. 3, increasing L-lysine HCl decreased ADG (linear, P < 0.01) and G:F (quadratic P < 0.03). In all three experiments, the greatest negative responses were observed when more than 0.15% L-lysine HCl was added to the diet. Therefore, unless other synthetic amino acids are added to the diet, no more than 0.15% L-lysine HCl should replace lysine from soybean meal in a cornor sorghum-soybean meal-based diet to avoid deficiencies of other amino acids. Based on the content of diets containing 0.15% Lysine-HCl, it appears the requirements for methionine plus cystine expressed as ratios relative to lysine are not greater than 50% during the early growing-finishing period (30 to 45 kg) and 62% during the late finishing period (90 to 120 kg) on a true digestible basis. For similar periods, the ratio requirements for threonine are not greater than 59% and 64% on a true digestible basis. Key Words: Growth, Lysine, Pigs

Dictyostelium Crp is a member of the cyclin-dependent kinase (Cdk) family of proteins. It is most related in sequence to mammalian Cdk5, which unlike other members of the family, has functions that are unrelated to the cell cycle. In order to better understand the function of Crp in Dictyostelium, we overexpressed a dominant negative form, Crp-D144N, under the control of the actin 15 promoter. Cells overexpressing Crp-D144N exhibit a reduced growth rate in suspension culture and reduced rates of fluid-phase endocytosis and phagocytosis. There is no reduction in Cdc2 kinase activity in extracts from cells overexpressing Crp-D144N, suggesting that the growth defect is not due to inhibition of Cdc2. In addition to the growth defect, the act15::crp-D144N transformants aggregate at a slower rate than wild-type cells and form large aggregation streams. These eventually break up to form small aggregates and most of these do not produce mature fruiting bodies. The aggregation defect is fully reversed in the presence of wild-type cells but terminal differentiation is only partially rescued. In act15::crp-D144N transformants, the countin component of the counting factor, a secreted protein complex that regulates the breakup of streams, mostly appears outside the cell as degradation products and the reduced level of the intact protein may at least partially account for the initial formation of the large aggregation streams. Our observations indicate that Crp is important for both endocytosis and efflux and that defects in these functions lead to reduced growth and aberrant development. Key Words: Dictyostelium; Cdk5; Cdc2-related kinase; differentiation; growth.

Research has been conducted on the heritability variation between traits, among populations and species. The variations of the tadpole growth rate heritability of the Swedish common frog have been investigated at different temperatures under laboratory conditions and the results are reported.

Research has been conducted on the CFU growth of Wallemia sebi in crystalline sugar. The effect of temperature, syrup film composition and water activity on the growth have been investigated and the results indicate that the CFU growth of W. sebi in sugar may be limited in nitrogen.

Twelve replications of four littermate pigs from a porcine reproductive and respiratory syndrome (PRRS) naive herd were weaned (11 [+ or -] 2 d of age) and penned individually in isolation rooms. Pigs were randomly allotted within litter to one of four dietary soy daidzein concentrations (0, 200, 400, or 800 ppm) to quantify the effect of daidzein on growth and immune response during a PRRS challenge. Daidzein was provided as the soy aglycone. At 27 [+ or -] 2 d of age (4.9 [+ or -] 1.4 kg BW), pigs were oronasally inoculated with [10.sup.4.3] PRRS virus/mL from strain JA142 in a 2-mL dose. Blood was collected every 4 d from d 0 to 24 after inoculation and analyzed for serum PRRS virus, interferon, and alpha-1-acylglycoprotein (AGP) concentrations. Serum virus and interferon peaked at [10.sup.5.3] virus/mL and 79% protection, respectively, at 4 d after inoculation and then declined steadily. Serum AGP concentration peaked at 12 d after inoculation. Each log increase in serum virus was associated with an increase in serum interferon, which resulted in a decrease of pig ADG and daily feed intake of 0.019 kg and 0.023 kg, respectively, in 5.8-kg pigs and a feed intake reduction of 0.024 kg in 12.5-kg pigs. Dietary daidzein additions did not (P > 0.3) alter the serum concentration after inoculation of PRRS virus ([10.sup.1.79], [10.sup.1.94], [10.sup.1.86], [10.1.93] virus/mL of serum) or AGP. Serum concentrations of interferon responded cubically (30.3, 28.9, 29.4, and 31.1% protection) as dietary daidzein concentrations increased; however, the magnitude of the response decreased over time. Dietary daidzein additions resulted in improvements in daily pig gain, daily feed intake, and gain/ feed during periods of peak viremia (d 4 to 16 after inoculation), but not in periods when systemic virus concentrations were minimized (d 16 to 24 after inoculation), resulting in a daidzein x days after inoculation interaction. Based on these data, the magnitude of the growth responses that occur in pigs infected with a virus is quantitatively related to the animal's serum concentration of the virus and interferon, and dietary soy daidzein at 200 or 400 ppm is a weak enhancer of body growth in vitally challenged pigs. Key Words: Growth, Pigs, Viral Replication

Fourteen foals between 4 and 4.5 mo of age were used to determine the effects of 12 mo of daily treatment with equine somatotropin (eST) on growth, metabolic, and hormonal characteristics. The foals were paired by sex, type, and lineage, and one of each pair was administered eST daily at 20 [micro]g/kg of BW. Body weights, body measurements, and assessments of glucose tolerance and feedback effects on endogenous somatotropin (ST) secretion were made routinely. Treatment with eST did not alter (P > 0.10) BW, height at withers, length of body, widths of chest and rump, heart girth, length of head, front or rear cannon lengths, front or rear cannon circumferences, gaskin circumference, or skin thickness, even though plasma IGF-I concentrations were doubled (P = 0.012). Glucose concentrations were higher (P = 0.03) in treated horses before glucose infusion; there was no difference (P > 0.10) in the glucose response to infusion. The insulin response to glucose infusion in the treated horses was generally higher (P = 0.0069) than in controls. Endogenous ST secretion in response to a ST secretagogue was reduced (P = 0.0001) in foals treated with eST in all months. The prolactin and thyroid-stimulating hormone responses to thyrotropin-releasing hormone on June 1 were not affected (P > 0.10) by treatment. In conclusion, daily treatment of growing horses with eST for 12 mo at the recommended dose altered the hormonal and metabolic characteristics known to be affected by ST but did not alter the growth characteristics of the animals. Key Words: Growth, Horses, Somatotropin

Research has been conducted on the Atlantic silverside exhibiting latitudinal variations in somatic growth rate. The hypothesis that the energy and growth maximization affects the ability to defend from the predators has been tested and the results demonstrate that the maximization of the energy intake and growth rate engenders fitness cost and increase the vulnerability to the predators.

Research has been conducted on the Atlantic silverside Menidia menidia populations which demonstrate genetic variations in the energy acquisition and allocation rates. The hypothesis that the rapid growth and high level of food consumption affect the locomotory performance in M. menidia has been tested and the results indicate that the high growth rates and large meal consumption diminish swimming performance and increase the vulnerability to predation.

Research has been conducted on the juvenile squids. The effect of the ration on the growth rate, statolith size and daily statolith increment width of these squids has been investigated and the results are reported.

Research has been conducted on the western terrestrial garter snake which vary in growth rate and life-history traits among adjacent populations in nature. The effect of the genetic and environmental components on the snake populations growth rates has been investigated and the results considered in the context of the population colonization history, migration and selection are presented.

Research is presented on the onset of growth spurt among adolescent Japanese based on data accumulated since 1915. Timing of maximum growth has decreased for both sexes, with the onset for growth spurts among boys decreasing and for girls remaining mostly constant, occurring generally between 6 and 8 years of age.

The physiological effects of extended larval lifetime in the bryozoan Bugula neritina were investigated. This was done by preventing the larvae of the cheilistomatid bryozoan from settling by means of mechanical agitation for one, four and eight hours after which settlement success and metamorphosis was examined. Results showed that extended larval lifetime had a significant impact on settlement, metamorphosis and post-larval growth. These results are explained in terms of the energetics of larval settlement and the role of protein content in this process.

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 [[micro]gram] 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 [[micro]gram] 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:gainby 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. Key Words: Pigs, Somatotropin, Endotoxins, Growth, Carcass Composition, Hormones

The biological effects of milk-borne insulin-like growth factor I (IGF-I) on the infant growth were analyzed in gastronomized suckling rats that were chronically fed with a rat milk substitute (RMS) without growth factors. Rat pups fed with RMS without peptide growth factors and supplemented with IGF-I exhibited enhanced weight gain and normal skeletal growth. Furthermore, IGF-I-fed animals exhibited enhanced enterocyte migration in the gastrointestinal tract tissues.

To study the relationship between diet and growth, a longitudinal anthropometric study was conducted in a Dutch population consuming a macro-biotic diet. Measurements (anthropometry and food habit questionnaire) were taken in 1985 (0-7 y), 1987, and in 1993 (7-16 y, n = 209). Z-scores were calculated for anthropometric measures and changes expressed as the differences between 1993 and the mean of 1985 and 1987. Analysis indicated significant (P < 0.002) catch-up in height [(mean Z-score [+ or -] SEM) + 0.59 [+ or -] 0.07] and arm circumference (+0.34 [+ or -] 0.09) for age (boys and girls combined). In 1993, both girls and boys were still significantly (P < 0.05) below the reference for height and sum of four skinfolds for age, and girls were below reference for weight-for-height and arm circumference for age. In girls, multiple regression analyses showed a significant positive effect of the consumption frequency of dairy products on catch-up growth in height, weight and arm circumference, after adjustment for menarche, age, and baseline height, weight and arm circumference (P < 0.05). The addition of moderate amounts of dairy products to a vegan type of diet improved growth of children, especially girls. J. Nutr. 126: 2977-2983, 1996. INDEXING KEY WORDS: * macrobiotic diet * catch-up growth * children * nutritional status * animal products

An investigation of fetal hypoxemia in lambs have provided evidence for the role of blood pressure and heart rate during growth restriction. A comparison of the systolic and diastolic pressures in control and experimental animals in the presence or absence of growth restriction showed that growth restriction in fetal hypoxemic lambs results in the decline of blood pressure and heart rate. A model for increasing growth restriction was developed.

The RNA/DNA ratios in the tropical scallop Euvola ziczac are a good indicator of growth in juveniles and physiological stress in fully mature scallops. The mature scallops have a lower RNA/DNA ratio than juvenile and maturing scallop. This is due to a decrease in seston quality rather than seston availability or temperature. In juveniles, the RNA/DNA ratio of the adductor muscle is related to growth.

Twelve recently weaned Hereford crossbred heifers weighing 227 kg (12 kg SD) and aged 230 d (8 d SD) on d 0 were used to investigate physiological responses associated with compensatory growth. Six heifers were allotted to ad libitum intake (ADLIB) and six were restricted to a maintenance diet for 95 d followed by realimentation (REST). Plasma collected from all heifers during feed restriction (d 0, 20, 48) and realimentation (d 104, 125, 153, 195) was analyzed for growth hormone (GH), insulin-like growth factor I (IGF-I), thyroid hormones (thyroxine [[T.sub.4]] and triiodothyronine [[T.sub.3]]), insulin, glucose, nonesterified fatty acids (NEFA), blood urea nitrogen (BUN), and 3-methyl histidine (3-MH). Resting metabolic rate (RMR) was measured 5 d before and 15 and 36 d after the beginning of realimentation. Feed restriction was associated with higher (P < .05) plasma concentrations of GH and NEFA and lower (P < .05) concentrations of IGF-I, [T.sub.4], [T.sub.3], insulin, and glucose. The BUN concentration was lower (P = .05) in REST than in ADLIB heifers on d 48, whereas 3-MH was not affected during the first 48 d of feed restriction. The RMR was lower (P < .05) in REST than in ADLIB heifers during feed restriction. During realimentation, the ADG of REST heifers was higher (P = .001) than that of ADLIB heifers. Concentrations of IGF-I, insulin, glucose, and NEFA in REST heifers increased and no differences (P > .05) between treatments were observed on d 104 (d 10 of realimentation) and thereafter. Conversely, GH concentration in REST heifers remained elevated through d 104 but dropped to ADLIB levels by d 125 (d 31 of realimentation). The [T.sub.4] and [T.sub.3] concentrations remained lower (P < .05) in REST than in ADLIB heifers after 10 d of realimentation but rose to control levels by d 31 of realimentation. The RMR was lower (P < .05) in REST than in ADLIB heifers 15 d into realimentation; however, no difference was found between treatments by d 36 of realimentation. These results indicate that enhanced growth rates in the early phase of compensatory growth are associated with the physiological response of the GH-IGF-I-insulin axis coupled with reduced maintenance requirement due to slower metabolic rate in restricted-refed heifers. Key Words: Feed Restriction, Realimentation, Physiological Responses, Beef Heifers

The tropical squid Photololigo sp. is able to lay multiple batches of eggs throughout its life. Ovaries of mature females always have immature and mature oocytes, which therefore do not mature simultaneously. The weight of oviduct is much less in comparison with body size and ovary weight indicating that the mature oocytes are not stored in the oviduct for a single spawning season. An examination of the changes in somatic growth reveals that immature females grow at double the rate of mature females, who have no large muscle fibres. Energetic demands of reproduction and somatic growth are discussed.

Growth in animals is defined as accretion of protein, fat, and bone. Although growth typically is measured as the change in live weight, nutrient retention is estimated more precisely by measuring empty body weight and composition, whereas production economics are measured ideally through carcass weights and quality. As a percentage of live weight gain, carcass weight gain usually is a much higher percentage during the feedlot phase than during the growing phase of production because dressing percentage (ratio of carcass:live weight) increases with maturation and is greater with concentrate than with roughage diets. At a given fraction of mature body size (maximum body protein mass), body fat percentage seems to be a constant. Mature size may be altered genetically and nutritionally. Protein accretion declines to zero when cattle reach their mature body size (approximately 36% fat in empty body weight in modern cattle) even though mature animals can continue to accrete fat. Although fat accretion can be reduced by limiting the supply of net energy, rate of fat accretion by finishing steers given ad libitum access to high-concentrate diets seems to reach a plateau at approximately 550 g daily. Protein mass, in contrast, increases in proportion to empty body weight. The protein:fat ratio of the carcass can be increased through increasing mature size, by administering hormones or hormonal modifiers, by limiting energy intake during the growing period or finishing period, or by slaughtering cattle at an earlier stage of maturity. Energetically, efficiency of accretion of fat is approximately 1.7 times that of protein. But because more water is stored with deposited protein than with deposited fat, lean tissue gain is four times as efficient as accretion of fat tissue. Conversion of protein to fat is very inefficient, suggesting that excess protein is utilized inefficiently. Key Words: Growth, Fat, Protein, Deposition, Feedlot Cattle

Infection in young growing animals is manifested by poor tissue protein accretion; during subsequent catch-up growth this is reversed. To account for these changes, protein synthesis and degradation were measured in vivo in skeletal muscle, skin, liver and small intestine in weanling rats during catch-up growth after Escherichia coil infection. Observations were made at d 4, 6, 8, 11 and 14, when infected rats had elevated nitrogen balance. Liver protein mass and turnover were not affected by treatment. Although protein mass of small intestine fell during infection, catch-up was achieved before d 4, suggesting a high priority for protein repletion in this tissue. On d 4, protein mass was lower (P < 0.05) in muscle (-19%) and skin (-23%) in infected vs. control rats. Thereafter growth rates of skeletal muscle and skin were higher (P < 0.001) in infected rats compared with controls. Catch-up growth was most pronounced early, but continued throughout the study. During catch-up growth, protein synthesis (mg/d) in muscle and skin was not different between control and infected animals. Protein synthesis was maintained in muscle because RNA mass was maintained. During catch-up growth in muscle and skin of infected rats, there was lower protein degradation (mg/d) than in controls (P < 0.05). We conclude that alterations in protein turnover during catch-up growth are tissue and time dependent and are different from those described in other hyperanabolic states. INDEXING KEY WORDS: catch-up growth; protein degradation; protein synthesis; infection; rats

Four trials were conducted to evaluate digestibility and growth efficiency caused by feeding heat-damaged protein. In Trial 1, 60 lambs (18.6 kg) were fed diets containing corn gluten meal (CGM) at five levels either of control (CGM-C) or heat-damaged (CGM-H), along with urea as the main supplemental N source. Efficiency of protein used for growth was determined by the slope-ratio technique. The heat damage to CGM decreased (P < .001) protein efficiency by 46%. In Trial 2, diets with the three highest CGM levels from Trial 1 were fed to 18 of the same lambs in a digestion trial. True N digestibility (TND) was 108% for CGM-C and was decreased (P < .05) 22% by heat damage. In Trial 3, 90 growing cattle (219 kg) were individually fed one of three protein supplements for 56 d. The protein supplement contained either a control source of dried distillers grains (DDG-C) or a heat-damaged source (DDG-H) at five levels, and a urea treatment was used as a negative control. Protein efficiency of DDG protein determined by the slope-ratio technique was decreased (P < .05) 34% by heat damage. In Trial 4, four yearling heifers (265 kg) were used in a 4 x 4 Latin square design to determine N digestibility of three diets used in Trial 3 (plus a diet not reported herein). True N digestibility averaged 98% for DDG-C and was decreased 7% by heat damage. These data suggest that some of the N in heat-damaged protein was absorbed postruminally but was not used for growth by growing ruminants.

Bioperiodicities in biological phenomena have long been studied to gain insight into the dynamics of living organisms. However, apparent periodicities in rates of growth and food intake have often been either ignored or attributed to random error. We have found that such periodicities are not random but take the form of infradian rhythms (period >28 h), with multiple periods including circasemiseptan (period = 3.5 d). In the reported experiments, we examine the existence of periodic, oscillatory phenomena in growth and eating patterns of rats. The cosinor model of Halberg was used to establish the occurrence of rhythms and quantify rhythm characteristics of components identified in least squares spectra. The four parameters of the rhythm were found to be altered by concentrations of the limiting dietary nutrient in that they had different spectral signatures. Existence of such oscillations in growth rates and food intake rates could have important consequences in designing feeding and growth experiments for achieving optimal physiological responses as well as providing possible insights into eating disorders.

Twenty barrows were designated as fast-growing (FG) and their littermates designated as slow-growing (SG) based on birth, weaning, and 56-d weight. Half of each group received 70 ||micro~gram~ of porcine somatotropin (pST)/kg BW daily beginning at 40 kg BW. At 60 and 105 kg BW, blood was collected every .5 h for 12 h beginning 1 h before pST injection, fat biopsies were taken for in vitro lipogenic activity, and insulin erythrocytes were isolated for receptor binding. Swine treated with pST had elevated ADG (.95 vs .88 kg/d; P |is less than~ .1) and reduced days to slaughter (61 vs 67; P |is less than~ .1). The pST-treated pigs had less average backfat (2.73 vs 3.96 cm; P |is less than~ .01), larger longissimus muscle areas (32.3 vs 28.2 |cm.sup.2~; P |is less than~ .05), and a higher percentage of muscle (56.3 vs 50.3%; P |is less than~ .01) than control pigs. Exogenous pST increased protein (17.4 vs 13.2%; P |is less than~ .05) and decreased fat (22.9 vs 37.1%; P |is less than~ .05). The FG pigs had higher ADG (.98 vs .86 kg/d; P |is less than~ .01) and required fewer days to slaughter (57 vs 71; P |is less than~ .01) than SG pigs. Administration of pST increased (P |is less than~ .01) average pST levels (1.7 vs 14.0 ng/mL) in FG and SG pigs at 60 kg BW. At 105 kg BW, pST was higher (P |is less than~ .01) in pST-FG than in pST-SG swine (46.0 vs 19.3 ng/mL) but was not different between FG and SG control swine (1.9 vs 1.8 ng/mL). Administration of pST increased concentrations of IGF-I (510.0 vs 160.0 ng/mL) and nonesterified fatty acids (182 vs 109 |Mu~Eq/L, P |is less than~ .01) in FG and SG swine. Over sample periods and growth rates, pST reduced (P |is less than~ .05) C|O.sub.2~ production and lipid synthesis (.345 and 1.85 vs .575 and 2.71 |Mu~mol of glucose incorporated|center dot~|g.sup.-1~|center dot~2 |h.sup.-1~). At 60 kg BW, FG swine had less (P |is less than~ .01) C|O.sub.2~ production and lipid synthesis (.299 and 1.83 vs .921 and 3.61 |Mu~mol|center dot~|g.sup.-1~|center dot~2 |h.sup.-1~) than did SG swine. Exogenous pST increased (P |is less than~ .05) binding to insulin erythrocyte receptors (7.25 vs 6.34%).

Northern Shrikes (Lanius excubitor) breed in a variety of habitats, including deserts. Deserts are characterized by unpredictable food supplies, which can lead to a slow growth rate of nestlings. However, given that Northern Shrike males use prey from their caches to augment freshly caught prey in providing food for their mates and nestlings, we hypothesized that their nestlings do not have a slow growth rate, but one that is equivalent to that in other passerine nestlings from temperate areas. To test this hypothesis, we measured growth rates and energy use in Northern Shrike nestlings and fledglings. We also measured energy expenditure in two adult males that were attending nests. Growth rate of Northern Shrike nestlings was similar to that predicted for passerines in temperate areas and therefore our hypothesis was supported. However, metabolizable energy available in the cache amounted to only is approximately equal to 7.2% of the total energy requirements of the nestlings or 4.2% of the total energy requirements of parents and nestlings during the nestling period. This suggested that other factors in addition to the cache were important in determining growth rate. These included (1) an extremely low maintenance energy requirement of the nestling; 30% of that predicted for a bird of its body mass when it weighed 10 g, which gradually increased to 70% at 50 g. This allowed for more of the energy intake to be used for growth and also reduced foraging costs of males; (2) the relatively low amount of body energy retained as a fraction of metabolizable energy intake, 0.15 to 0.16, indicating that more water per unit growth was incorporated than in other passerines. Energy expenditure of adult males was substantially lower than that predicted for a passerine of similar body mass. Males collected 4.83 times the energy that they consumed in order to provide their mates and offspring with food. Yet, their ratio of field metabolic rate to basal metabolic rate was only 2.33, the lowest reported value for adults feeding altricial young.

Feedlot steers were implanted with varying doses of recombinant bovine somatotropin (rbST) to determine the maximally effective dose for growth performance and carcass protein deposition. The results showed that rbST increased growth performance. Weekly rbST implants of the maximally effective dose of 160 mg/week increased carcass protein deposition and decreased carcass fat. Dressing percentage was not affected, indicating that the primary effect of rbST is on the carcass and not on the non-carcass components.

Rats were pair-fed ethanol and control liquid diets to investigate the influence of chronic ethanol ingestion on insulin-like growth factor I (IGF-I). Ethanol appears to hamper growth by modifying this aspect of the growth-promoting endocrine system. The effect of two different feeding schedules was also investigated. When meal-fed the day before testing, serum IGF-I and hepatic IGF-I mRNA levels remained normal. However, when animals received their entire ration in one feeding, these IGF-I levels were significantly elevated, implying a nutritional dissimilarity despite identical dietary caloric content.

This review discusses the function of COP9 signalosome protein in eukaryotes in which COP9 is critical for the proper development of multicellular organisms. Research indicates that COP9 promotes SCF ubiquitin ligases and other cullin-based ubiquitin ligases.

Research examines the importance of protein concentration and the rate of protein biosynthesis in cell growth in that protein content is correlated with cell volume, the RNA:DNA ratio with the number of ribosomes per cell and the RNA:protein ration with the ribosome concentration, which in turn reflects protein synthesis rate.

In this paper a model, developed from incorporating initial conditions of temperature, pH, and nutrient status, is used to estimate the growth and self-inhibition dynamics of a bacteriocin producing Lactobacillus sakei CTC 494 culture. Analysis indicates that the model is experimentally verifiable.

This study documented the effect of changes in male and female sex hormones and the selective estrogen receptor modulator (SERM) tamoxifen on weight gain and food consumption of rats from puberty to adulthood, and assessed whether age at onset of treatment affected outcome. In Study 1, male and female WKY rats were either neutered or sham-operated before puberty, and a subgroup of neutered females underwent estrogen replacement (ERT) at the age of puberty. In Study 2, subgroups of neutered females received either ERT or tamoxifen beginning well into the postpuberty period. Weekly body weight and food consumption were assessed, and food consumption was normalized to metabolic weight (body [weight.sup.0.67]). Neutering reduced the rate of weight gain in males (P [is less than] 0.05), but significantly increased it in females (P [is less than] 0.0001). ERT immediately reduced weight gain and prevented any further increase, resulting in weights below that of sham-operated females (P [is less than] 0.05). Tamoxifen prevented further weight gain and returned profiles to that of sham-operated females. Food consumption, normalized to metabolic weight, was similar in females and males, and both sexes showed a decrease through maturation to adulthood. Neutering decreased food consumption below that of sham-operated animals in both males and females (P [is less than] 0.05), and ERT returned it to sham levels. Despite the fact that tamoxifen had an effect on body weight similar to that of ERT, females receiving tamoxifen treatment consumed less food than both sham-operated and ERT females (P [is less than] 0.05). Weight gain is modulated by sex hormones in male and female rats, with both estrogen and tamoxifen exerting immediate effects in females, irrespective of the age at which treatment is initiated. Differences in food consumption do not appear to account for the effects of hormones and tamoxifen on body weight, suggesting that they exert a direct effect on overall body metabolism. J. Nutr. 131: 2351-2357, 2001. KEY WORDS: * gender * food consumption * growth * 17[Beta]-estradiol * tamoxifen * rats

We present body mass (N = 419) and crown-rump length (CRL, N = 210) measurements from 38 male and 49 female mandrills born into a semifree-ranging colony in order to describe growth from birth to adulthood, and to investigate maternal influences upon growth. Adult male mandrills are 3.4 times the body mass, and 1.3 times the CRL, of adult females. Body mass dimorphism arises from a combination of sex differences in length of the growth period (females attain adult body mass at 7 years, males at 10 years) and growth rate. Both sexes undergo a subadult growth spurt in body mass, and this is much more dramatic in males (peak velocity 551 g/months [+ or -] 89 SEM at 84-96 months). CRL dimorphism arises from bimaturism (females attain adult CRL at 6 years, males after 10 years), and neither sex shows a particular subadult growth spurt in CRL. Sexual size dimorphism thus represents important time and metabolic costs to males, who mature physically approximately 3-4 years after females. Considerable interindividual variation occurs in the size-for-age of both sexes, which is related to maternal variables. Older mothers have heavier offspring than do younger mothers, and higher-ranking mothers have heavier offspring than do lower ranking mothers. Mass advantages conferred upon offspring during lactation by older and higher-ranking mothers tend to persist postweaning in both sexes. Thus maternal factors affect reproductive success in both sexes, influencing the age at which offspring mature and begin their reproductive career. Am J Phys Anthropol 115:349-360, 2001. KEY WORDS body mass; crown-rump length; subadult growth spurt; female age; female rank; parity

A prominent feature of comparative life histories in fish (and other indeterminate growers) is the approximate invariance across species of certain dimensionless numbers made up from reproductive and timing variables. The two best known are the age at maturity ([Alpha]) divided by the average adult lifespan (E), and the proportion of a body mass given to reproduction per year (c) multiplied by E. This article uses evolutionary life-history theory for nongrowing populations to predict the numeric value of these numbers for fish and lizards, with several new implications for the dynamics of ontogenetic development. dimensional analysis | ESS | fish | ontogeny | reptiles

Pacific Salmon typically spend 1-3 years foraging and growing in the ocean prior to returning to freshwater spawning sites. Inter-annual differences in ocean temperatures and productivity may have profound effects on the growth of these animals. Growth variation may influence age of maturation, size at maturation, and overall year-class survival. Thus, understanding variation in oceanic growth rates is important to understanding variation in the fitness of Pacific salmon. However, it is very difficult to measure oceanic growth rates. Growth is mediated by the endocrine system; consequently, endocrine correlates of growth may provide a valuable tool for assessing relative growth rate and related fitness values, based on a single blood sample. We conducted an experiment relating growth rate to plasma hormone levels in order to test this idea. Specifically, we individually tagged approximately 1200 yearling coho salmon, placed them in seawater tanks and assessed growth at two month intervals. Plasma was obtained in September and November and we found a significant, highly correlated (r2 [is greater than] 0.5) relation between IGF-I and growth rate. We found little relation between insulin and growth. Subsequently, we obtained samples from coho salmon in the Strait of Georgia and Puget Sound (West Coast of North America). IGF-I data obtained from these samples shows both geographic and interannual variability. These preliminary data suggest that a more extensive sampling regime (geographically and temporally) for IGF-I levels of Pacific salmon may give us insight into environmental factors regulating growth and fitness.

Energetic response to repeated restraint stress in rapidly growing mice. Am J Physiol Endocrinol Metab 279: E33-E43, 2000.--There is a cost of stress that may result in the loss of normal biological function (e.g., growth). Repeated, and even single, applications of stressors have been shown to induce negative energy balance in rodents. However, here we addressed whether this energetic response changes during multiple stress exposure and whether there is complete recovery subsequent to the cessation of stress exposure. These questions were addressed in growing C57Bl/6 mice (31 day) by determining at different times the energetic and endocrine responses after the exposure to restraint (R) stress for 4 h applied once (R1), repeatedly over 3 days (R3), or repeatedly over 7 days (R7). Compared with control values, R elevated (P [is less than] 0.05) plasma corticosterone and reduced plasma insulin-like growth factor I on all days of exposure to the stressor. Seven days, but not 1 or 3 days of R, decreased the net growth (126%, P [is less than] 0.05) and deposition of fat (71%, P [is less than] 0.05) and lean (60%, P [is less than] 0.05) energy over the 7 days. Only R7 depressed the 7-day metabolizable energy intake (P [is less than] 0.05), and R7, but not R1 or R3, increased the overall energy expenditure (10%, P [is less than] 0.05). Our results demonstrate that repeated episodes of stress are energetically costly to the rapidly growing animal, but compensatory mechanisms mitigate this cost of repeated stress exposure and permit complete recovery of energy balance after the cessation of stress application. growth; energy partitioning; feed intake; corticosterone

The inhibition of growth is a cardinal symptom of zinc deficiency. In animals fed a zinc-inadequate diet, both food intake and growth are reduced within 4-5 d. Despite the concomitant reduction in food intake and growth, reduced energy intake is not the limiting factor in growth, because force-feeding a zinc-inadequate diet to animals fails to maintain growth. Hence, food intake and growth appear to be regulated by zinc through independent, although well coordinated, mechanisms. Despite the long-term study of zinc metabolism, the first limiting role of zinc in cell proliferation remains undefined. Zinc participates in the regulation of cell proliferation in several ways; it is essential to enzyme systems that influence cell division and proliferation. Removing zinc from the extracellular milieu results in decreased activity of deoxythymidine kinase and reduced levels of adenosine(5')tetraphosphate(5')-adenosine. Hence, zinc may directly regulate DNA synthesis through these systems. Zinc also influences hormonal regulation of cell division. Specifically, the pituitary growth hormone (GH)-insulin-like growth factor-I (IGF-I) axis is responsive to zinc status. Both increased and decreased circulating concentrations of GH have been observed in zinc deficiency, although circulating IGF-I concentrations are consistently decreased. However, growth failure is not reversed by maintaining either GH or IGF-I levels through exogenous administration, which suggests the defect occurs in hormone signaling. Zinc appears to be essential for IGF-I induction of cell proliferation; the site of regulation is postreceptor binding. Overall, the evidence suggests that reduced zinc availability affects membrane signaling systems and intracellular second messengers that coordinate cell proliferation in response to IGF-I. J. Nutr. 130: 1500S-1508S, 2000. KEY WORDS: * zinc * cell proliferation * IGF-I * growth hormone * DNA synthesis

Linderman, J. R., and M.A. Boegehold. Growth-related changes in the influence of nitric oxide on arteriolar tone. Am. J. Physiol. 277 (Heart Circ. Physiol. 46): H1570-H1578, 1999.--This study was designed to determine whether juvenile growth is accompanied by changes in the local influence of nitric oxide (NO) or prostaglandins on arteriolar tone. In vivo microscopy was used to study proximal arterioles in the spinotrapezius muscle of rats 4-5 wk (weanling), 7-8 wk (juvenile), and 11-12 wk (mature) of age. From 4 to 12 wk of age, arterioles underwent an increase in resting diameter (from 31 [+ or -] 2 to 49 [+ or -] 2 [micro]m) and volume flow (from 7 [+ or -] 1 to 10 [+ or -] 1 nl/s) but a decrease in resting wall shear rate (from 1,901 [+ or -] 150 to 748 [+ or -] 50 [s.sup.-1]). NO synthase inhibition with [N.sup.G]-monomethyl-L-arginine (L-NMMA) had no effect on arteriolar diameters in weanling rats but reduced diameters by 14 [+ or -] 4% in juvenile rats and by 13 [+ or -] 4% in mature rats. Cyclooxygenase inhibition with meclofenamate reduced arteriolar diameters by a similar amount (13 [+ or -] 4 to 18 [+ or -] 3%) in all age groups. There were no age-related differences in arteriolar responsiveness to locally applied sodium nitroprusside or prostaglandin [E.sub.2]. Arteriolar responsiveness to ACh was also similar in all groups, but the L-NMMA-sensitive portion of this response was smaller in mature rats than in weanling rats. Elevation of flow-related shear stress caused arteriolar dilation in juvenile rats but not in weanling rats. These findings suggest that arteriolar smooth muscle responsiveness to NO or prostaglandins does not change during juvenile growth and that basally released vasodilator prostaglandins exert a constant influence on arteriolar tone throughout this period. Basal NO activity also modulates arteriolar tone in juvenile and mature rats but not in weanling rats. In contrast, agonist-stimulated NO release is prominent in weanling and juvenile rats but somewhat decreased in mature rats, where cyclooxygenase products also contribute to ACh induced dilation. microcirculation; endothelium; endothelium-derived relaxing factor; prostaglandins; maturation; tissue growth

The somatostatin (SS) family of peptides regulate various aspects of animal growth, development, and metabolism. The multi-functional nature of the SS family stems from the molecular heterogeneity of the peptides themselves as well as from variations in the signaling systems of target cells. The diversity of SS structure can be explained by differential processing of a single precursor molecule and by the existence of multiple SS genes. Organisms regulate the relative abundance of the SS isoforms by controlling differential expression of the various SS genes and/or by controlling tissue-specific processing of precursor molecules. In some cases, SS isoforms elicit similar effects, while in other cases, the isoforms provoke different cellular responses. In rainbow trout, for example, both SS-14 and salmonid SS-25 (sSS-25), which contains [[Tyr.sup.7], [Gly.sup.10]]-SS-14 at its C-terminus (and is derived from gene separate from that giving rise to SS-14), inhibit glucagon release; whereas, only sSS-25 inhibits insulin release. The effect of a specific SS isoform depends on the presence and function of the appropriate signaling system in the target cell. (Supported by NSF IBN 9723058.)

Teleost fishes are like most other vertebrates in that total plasma IGF-I and GH correlate positively and negatively with ration. We examined the relations between ration, growth, IGF-I and GH in salmon. Tanks of tagged fish were placed on high, medium, or low ration and sampled biweekly for eight weeks. Some fish received nonlethal blood draws, while others were killed. IGF-I increased in early September in all groups. GH peaked after the switch to low ration. Serial blood draws decreased hematocrit, growth, and IGF-I but did not affect GH. IGF-I changes over time in serially sampled fish suggested an approximately four week cycle in IGF-I. Possible cycles in length growth were also found. No relation was evident between growth and GH. In all fish, total plasma IGF-I was weakly positively correlated with length growth. Stronger correlations were obtained when repeated IGF-I measures in serial fish were averaged. Groups of fish showing IGF-I and length growth cycles had the strongest correlations between length growth and IGF-I.

A 14-d growth assay was conducted to determine the optimal apparent digestible isoleucine:lysine ratio to maximize growth performance of the early-weaned pig. A total of 360 pigs (initially 5.6 kg and approximately 18 d of age, PIC C22 x 327) were blocked by weight and allotted randomly to 12 dietary treatments. Each treatment had 6 replications and 5 pigs per pen. Corn, soybean meal, spray-dried animal plasma, blood cells, fish meal, and spray-dried whey were analyzed for amino acid profiles prior to diet formulation. The 12 treatments consisted of two basal diets containing 1.00 and 1.26% apparent digestible lysine with .45 and .57% apparent digestible isoleucine, respectively. Crystalline isoleucine was added to each of the basal diets to provide concentrations of 50, 55, 60, and 65% of lysine. Two positive control diets contained 1.10 and 1.39% apparent digestible lysine. An isoleucine x lysine interaction (P Key Words: Isoleucine, Lysine, Weanling pigs