Identification of quantitative trait loci affecting carcass composition in swine: II. Muscling and wholesale product yield traits

A genomic scan was conducted on 540 reciprocal backcross Meishan x White composite pigs for hot carcass weight (HCWT); loin eye area (LOIN); carcass length (CRCL); belly weight (BELLY); and weight of trimmed ham, loin, picnic, and Boston butt adjusted to a constant live (TWPLWT) or carcass (TWPCWT) weight. Genetic markers spanned the entire porcine linkage map and were spaced at approximately 20-cM intervals. Grandparental breed of origin for all chromosomal segments was determined using multipoint linkage procedures, and a least squares regression analysis was conducted. Nominal P-values were converted to a genome-wide level of significance to adjust for the number of tests actually conducted. Seven associations were significant at the genome-wide level relating to chromosomes 1 (SSC 1), 7 (SSC 7), and X (SSC X). The SSC 1 region affected LOIN, TWPLWT, and TWPCWT; SSC 7 affected HWCT and CRCL; and SSC X affected TWPLWT and TWPCWT. Twelve associations relating to seven chromosomal regions (including SSC 1 and X) presented suggestive evidence for quantitative trait loci (QTL), and many of these regions are likely to contain QTL. Chromosomes 8 and 14 had two and three traits with suggestive evidence for QTL, respectively. Many pleiotropic effects were detected for regions on SSC 1, 7, 14, and X in this study and a companion study looking for fat deposition QTL in the same population. In addition, SSC 4 was nearly significant for CRCL in the same region identified as affecting backfat in a wild boar x Large White population. These results expand our knowledge of the inheritance of quantitative traits and are directly relevant to composite populations containing Meishan germplasm.     

Quantitative trait loci affecting body weight and fatness from a mouse line selected for extreme high growth

Quantitative trait loci (QTL) influencing body weight were mapped by linkage analysis in crosses between a high body weight selected line (DU6) and a control line (DUKs). The two mouse lines differ in body weight by 106% and in abdominal fat weight by 100% at 42 days. They were generated from the same base population and maintained as outbred colonies. Determination of line-specific allele frequencies at microsatellite markers spanning the genome indicated significant changes between the lines on 15 autosomes and the X chromosome. To confirm these effects, a QTL analysis was performed using structured F2 pedigrees derived from crosses of a single male from DU6 with a female from DUKs. QTL significant at the genome-wide level were mapped for body weight on chromosome 11; for abdominal fat weight on chromosomes 4, 11, and 13; for abdominal fat percentage on chromosomes 3 and 4; and for the weights of liver on chromosomes 4 and 11, of kidney on chromosomes 2 and 9, and of spleen on chromosome 11. The strong effect on body weight of the QTL on chromosome 11 was confirmed in three independent pedigrees. The effect was additive and independent of sex, accounting for 21-35% of the phenotypic variance of body weight within the corresponding F2 populations. The test for multiple QTL on chromosome 11 with combined data from all pedigrees indicated the segregation of two loci separated by 36 cM influencing body weight.     

Congenic strain confirms putative quantitative trait locus for body weight in the rat

Quantitative trait loci (QTLs) affecting body weight were investigated in the backcross population derived from non-diabetic BB/OK and spontaneously hypertensive rat (SHR) strains. The F1 hybrids were backcrossed onto SHR rats, and QTL analysis was performed separately with the resulting backcross populations for each sex on Chromosomes (Chrs) 1, 3, 4, 10, 13, and 18. The body weight was determined at the age of 14 weeks, and the statistical analysis was performed with MAPMAKER/QTL 1.1b computer program. According to the stringent threshold for a lod score of 3.0, markers on Chr 1 were found to be linked with body weight. The QTL with a peak lod score (5.1) on Chr 1 for a male population was located within markers Igf2 and D1Mgh12. In contrast, in the female population the body weight affecting QTL (lod = 5.7) on Chr 1 was located between the D1Mit3 and Lsn markers. The existence of QTLs on Chr 1 affecting body weight in the male population was confirmed by congenic BB.Sa rats, carrying chromosomal region of SHR (Sa-Igf2) on the genetic background of BB rat.     

Mapping quantitative trait loci for carcass and meat quality traits in a wild boar x Large White intercross

An intercross between wild boar and a domestic Large White pig population was used to map quantitative trait loci (QTL) for body proportions, weight of internal organs, carcass composition, and meat quality. The results concerning growth traits and fat deposition traits have been reported elsewhere. In the present study, all 200 F2 animals, their parents, and their grandparents were genotyped for 236 markers. The marker genotypes were used to calculate the additive and dominance coefficients at fixed positions in the genome of each F2 animal, and the trait values were regressed onto these coefficients in intervals of 1 cM. In addition, the effect of proportion of wild boar alleles was tested for each chromosome. Significant QTL effects were found for percentage lean meat and percentage lean meat plus bone in various cuts, proportion of bone in relation to lean meat in ham, muscle area, and carcass length. The significant QTL were located on chromosomes 2, 3, 4, and 8. Each QTL explained 9 to 16% of the residual variance of the traits. Gene action for most QTL was largely additive. For meat quality traits, there were no QTL that reached the significance threshold. However, the average proportion of wild boar alleles across the genome had highly significant effects on reflectance and drip loss. The results show that there are several chromosome regions with a considerable effect on carcass traits in pigs.     

Effects of 6-N-propyl-2-thiouracil on growth, hormonal profiles, carcass and reproductive traits of boars

Neonatal 6-N-propyl-2-thiouracil (PTU)-induced hypothyroidism reduces body weight but increases testicular size in adult male rodents. The objective of this study was to determine the effect of prepubertal PTU treatment on boars. For Experiment I, boars (n = 28) were randomly allotted to eight pens. Each pen received one of four PTU doses (0, 0.01, 0.03 and 0.1% in a basal diet) between 28 and 56 days of age (DOA). Due to a lack of difference among three PTU treatments, PTU-treated boars were pooled. Boars treated with PTU had lower (P < 0.05) ADG during treatment, lighter (P < 0.05) BW after 56 DOA and less (P < 0.05) developed epididymides at 154 DOA. For Experiment II, boars (n = 19) were randomly allotted to six pens. Each pen received one of three PTU treatments orally as: control (carrier), PTU-I (0.002% BW of PTU daily between 7 and 70 DOA), or PTU-II (0.002% BW of PTU daily between 28 and 91 DOA). During treatment, PTU-treated boars had lower (P < 0.05) serum T4 levels, rectal temperature, feed intake and ADG. Boars treated with PTU had lower (P < 0.05) BW between 63 and 154 DOA but higher (P < 0.05) gain/feed between 105 and 133 DOA. Boars treated with PTU had less (P < 0.05) developed epididymides and sperm count per gram testis at 238 DOA. These results suggest that prepubertal PTU-induced hypothyroidism had significant effects on growth, hormonal profiles, and reproductive traits of boars; however, it does not appear to be an effective method for increasing testis size and sperm production of commercial boars.     

Effects of carbon dioxide pneumoperitoneum, air pneumoperitoneum, and gasless laparoscopy on body weight and tumor growth

BACKGROUND: The oncologic consequences of intraperitoneal carbon dioxide (CO2) insufflation during the laparoscopic resection of cancer are under debate. The effect of other insufflating gases or gasless laparoscopy on cancer requires study. OBJECTIVE: To study body weight and tumor growth in rats after CO2 pneumoperitoneum, air pneumoperitoneum, and gasless laparoscopy. METHODS: On day 1, an 8-mg bolus of ROS-1 tumor was placed under the renal capsule of both kidneys in rats. In experiment A, rats had either CO2 insufflation (n=10) or a gasless laparoscopic bowel resection (n=10) on day 3 and were humanely killed after 7 days. In experiment B, rats had either a laparoscopic bowel resection with CO2 insufflation (n=11) or insufflation with air (n=11) on day 3 and were killed after 7 days. In both experiments, postoperative weight loss and tumor growth were measured, and the differences were tested with an analysis of covariance. RESULTS: Renal subcapsular tumor growth in the group having gasless laparoscopy was less than that in the group having CO2 pneumoperitoneum (P=.04). Postoperative weight loss in these groups showed no differences (P=.55). No differences in tumor growth or weight loss were found between rats having insufflation with CO2 and those having insufflation with air (P=.61 and P=.68, respectively). CONCLUSIONS: The restoration of body weight after a laparoscopic surgical procedure was similar with CO2, air, or gasless laparoscopy. Gasless laparoscopy was associated with less renal subcapsular tumor growth than was insufflation with CO2. Therefore, the application of gasless techniques in laparoscopic oncologic surgical treatment demands further study.     

Can health care assistants replace student nurses?

Quantitative trait loci (QTLs) affecting body weight were investigated in the backcross population derived from diabetic BB/OK and spontaneously hypertensive rat (SHR). The F1 hybrids were backcrossed onto BB/OK rats, and QTL analysis was performed with the resulting backcross population on chromosomes 1, 3, 4, 10, 13 and 18. According to the stringent threshold for a lod score of 3.0, markers on chromosomes 1 and 4 were found to be linked with body weight. The QTL with a peak lod score (3.3) on chromosome 1 for a male population was located within the region flanked by loci Igf2 and D1Mgh12. On chromosome 4, linkage between the body weight and the region around the Npy locus was observed (lod score 3.1). The existence of the QTL on chromosome 4 affecting body weight was confirmed by congenic BB.LL rats, carrying chromosomal region of SHR (D4Mit6-Npy-Spr) on the genetic background of the BB/OK rat.     

Optimal protein requirements during the first 2 weeks after the onset of critical illness

OBJECTIVE: To obtain optimal protein requirements in critically ill sepsis or trauma patients during the first 2 wks after admission to the intensive care unit. DESIGN: Retrospective study. SETTING: Department of critical care medicine at a teaching hospital. PATIENTS: Immediate posttrauma patients or severely septic patients. INTERVENTIONS: In vivo neutron activation analysis was used to measure changes in total body protein over a 10-day period which began as soon as the patients were hemodynamically stable. The patients (trauma, n=18; sepsis, n=5) were divided into three groups according to the average daily protein intakes. Because the patients were overhydrated (approximately 10 L) and had variable amounts of body fat, the protein intakes were indexed to normally hydrated (corrected) fat-free mass (FFMc): Groups A, B, and C received an average of 1.1, 1.5, and 1.9 g/kg FFMc/day protein, respectively. MEASUREMENTS AND MAIN RESULTS: Overall, the average loss of total body protein was 1.2=0.7 (SD) kg. Changes in total body protein were significantly (p=.011) different between the three groups. The loss of body protein was significantly more in group A compared with groups B (p=.013) and C (p=.023). When the protein intake was increased from 1.1 g/kg FFMc/day to 1.5 g/kg FFMc/day, protein loss was halved. Further increase in protein intake up to 1.9 g/kg FFMc/day resulted in no further improvement. An intake of 1.5 g/kg FFMc/day was equivalent to 1.0 g/day/kg of body weight measured at the beginning of the study. CONCLUSIONS: Current recommended protein requirements of 1.2 to 2.0 g/kg of body weight/day are excessive if they are indexed to the body weight measured soon after the onset of critical illness. Because individual patients have varying degrees of overhydration early in the illness onset, we suggest that the intensivist should obtain information on preillness body weight and prescribe 1.2g of protein/kg body weight/day. If information is not available, 1.0g of protein/day/kg of measured body weight will give a fair approximation to optimal protein requirements.     

Effects of repeated urea dilution measurement on feedlot performance and consistency of estimated body composition in steers of different breed types

Steers (20 Bos indicus cross [BIX] and 20 Bos taurus cross [BTX]) were randomly assigned to a 2x2 factorial experiment within two weight blocks per treatment 1) to study the effects of repeated urea dilution (UD) measurement on feedlot performance and 2) to determine the consistency of estimated body composition in steers of different breed types. Weights were taken on d 0, 42, 84, 126, and 140. Urea dilution was determined on half of the pens in the experiment, and ultrasonic measurement of backfat (BF) was performed on all cattle on d 0, 42, 84, and 126. Pen means of all performance variables were used in the analysis of variance. Carcass data were analyzed on an individual basis. Within periods, ADG was inconsistent between controls and steers on which UD was determined (1.95 vs 2.03, 1.61 vs 1.28, 1.51 vs 1.71, and 1.77 vs 1.47 kg, P = .23, .02, .09, and .11, respectively, for Periods 1, 2, 3, and 4, SEM = .07). Overall, UD had no effect (control vs UD, respectively) on ADG (1.70 vs 1.68 kg, P = .77, SEM = .07), DMI (8.26 vs 8.03 kg, P = .69, SEM = .36), gain efficiency (207 vs 209 g BW gain/kg DMI, P = .78, SEM = 2.34), hot carcass weight (HCWT; 360 vs 358 kg, P = .90, SEM = 2.52), or percentage of estimated carcass fat, (ECF; 38.8 vs 37.0%, P = .61, SEM = 1.05). Breed types (BIX vs BTX, respectively) had similar ADG (1.74 vs 1.64 kg, P = .27, SEM = .14), DMI (7.96 vs 8.30 kg, P = .50, SEM = .36), backfat thickness (16.4 vs 15.0 mm, P = .30, SEM = .45), and ECF (38.9% vs 36.6%, P = .48, SEM = 2.01). Urea dilution estimated empty body fat values increased with days on feed (14.4+/-1.36; 22.7+/-1.47; 26.0+/-1.36; 30.4+/-1.47%, respectively, for d 0, 42, 84, and 126). Using yield grade factors to calculate ECF consistently produced a value that was higher than empty body fat determined by UD (UDEBF) 14 d prior to slaughter (36.9+/-1.73 vs 30.4%+/-0.17). Significant correlation coefficients were found for the pooled data between UDEBF vs BF, r = .84; UDEBF vs live weight, r = .99; UDEBF vs ECF, r = .82; and UDEBF vs percentage of carcass protein, r = -.99. This study demonstrated that there are no detrimental effects of the urea dilution procedure on performance characteristics of feedlot cattle. Beef cattle of different breed types may be accurately evaluated with urea dilution.     

The xenon-enhanced computed tomography cerebral blood flow method

It has been proposed that one of the primary events in the development of essential hypertension is a growth-related process initiated as early as during fetal development. Differences in kidney size have been observed between most rat models of hypertension and their respective controls. In this study, we analyzed relative kidney size (kidney weight/body wt) in a set of rat recombinant inbred strains (RIS) (N = 27) and their progenitors, the spontaneously hypertensive rat strain (SHR/Ola) and Brown Norway congenic strain (BN.1x), at two different ages, at birth and at 15 weeks. In the progenitors, the relative kidney weight was higher in the hypertensive than in the normotensive strain of both the newborn (P < 0.001) and adult (P < 0.001) animals. In the RIS, a significant correlation was found between the newborn and adult relative kidney weight (r = 0.49, P = 0.01), indicating that the two phenotypes share some of their genetic determinants. A total genome search of newborn and adult relative kidney weight was performed with a total of 453 genetic markers. These analyses revealed several suggestive quantitative trait loci (QTL), some of which were, indeed, significant for both newborn and adult relative kidney weight (such as, D3Mit9 on rat chromosome 3; r = -0.50, P < 0.01; r = -0.47, P < 0.01; respectively). Others, such as the locus on rat chromosome 1 (Rt6; r = -0.43, P < 0.05), were significant only for the adult relative kidney size. This QTL was found in close proximity to a region previously related to susceptibility to hypertensive renal disease in the fawn-hooded rat and, similarly to that study, its effect was found to be independent of blood pressure. Furthermore, a growth pattern of the kidneys after birth, evaluated as the difference between the newborn and adult relative kidney weight, was also subjected to total genome scan. Several suggestive QTL were identified. One of the most significant loci was found at the D1a marker on rat chromosome 17 (r = -0.51, P < 0.01), which was previously related to the determination of adult heart weight in the RIS. In conclusion, the current study demonstrates the usefulness of RIS in studies of hypertension-related phenotypes, some of which are abnormal before the development of high blood pressure. To better understand their role in the pathogenesis of hypertension, studies at different ages are needed, which are uniquely feasible in RIS.     

Holiday weight management by successful weight losers and normal weight individuals.

This study compared weight control strategies during the winter holidays among successful weight losers (SWL) in the National Weight Control Registry and normal weight individuals (NW) with no history of obesity. SWL (n = 178) had lost a mean of 34.9 kg and had kept ≥13.6 kg off for a mean of 5.9 years. NW (n = 101) had a body mass index of 18.5-24.9 kg/m2. More SWL than NW reported plans to be extremely strict in maintaining their usual dietary routine (27.3% vs. 0%) and exercise routine (59.1% vs. 14.3%) over the holidays. Main effects for group indicated that SWL maintained greater exercise, greater attention to weight and eating, greater stimulus control, and greater dietary restraint, both before and during the holidays. A Group × Time interaction indicated that, over the holidays, attention to weight and eating declined significantly more in SW than in NW. More SWL (38.9%) than NW (16.7%) gained ≥1 kg over the holidays, and this effect persisted 1 month later (28.3% and 10.7%, respectively). SWL worked harder than NW did to manage their weight, but they appeared more vulnerable to weight gain during the holidays. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An evaluation of ruminally degradable intake protein and metabolizable amino acid requirements of feedlot calves

Ruminally degradable intake protein (DIP) and metabolizable indispensable amino acid (MIAA) requirements of feedlot steers were evaluated. Dietary treatments consisted of isocaloric 80% concentrate steam-flaked corn-based diets containing either .8% urea, 1.5% fish meal (FM), 3.0% FM, 4.5% FM, or 4.5% soybean meal (SBM). Treatment effects on characteristics of ruminal and total tract digestion were evaluated using four Holstein steers (249 kg) with cannulas in the rumen and proximal duodenum. Ruminal digestibility of OM (RDOM; P < .05) and feed N (P < .01) and microbial N flow (MNF; P < .01) to the small intestine were greater with urea as the supplemental N source. The level of DIP was closely associated (R2 = .89) with MNF. Postruminal digestibility of OM was greater (P < .05) for FM than for urea-supplemented diets, compensating for lower RDOM. There were no treatment effects (P > .10) on DOM. As the level of FM was increased, MIAA increased linearly (P < .01). Intestinal MIAA were similar (P > .10) for urea- and SBM-supplemented diets. Treatment effects on 56-d growth performance were evaluated using 100 medium-framed crossbred steers (231 kg). Daily weight gain (linear effect; P < .01), DM intake (linear effect; P < .10), feed efficiency (linear effect; P < .05), and diet NE (linear effect; P < .05) increased with level of FM supplementation. Daily weight gain (P < .10) and DM intake (P < .05) were greater for urea- than for SBM-supplemented diets. Using bovine tissue as the reference protein, the biological value (based on chemical score) of the intestinal chyme protein averaged 73%; methionine was first-limiting. There was a close association (R2 = .99) between methionine supply to the small intestine and observed/expected dietary NE. The metabolizable methionine requirement (MMETR, g/d) of medium-framed feedlot steers can be reliably predicted from measures of BW and ADG (MMETR = 1.565 + .0234ADG[268 - (29.4 x .0557BW(.75)ADG(1.097))/ADG] + .0896BW(.75)). There was a very close association (R2 = .89) between DIP and MNF (MNF = 13.7DIP - .66DIP(2) + 25.9). At maximal observed synthesis, DIP accounted for 76% of the MNF. A minimum of 100 g DIP/kg of total tract digestible OM was required to maximize RDOM and MNF.     

Evaluation of enzymatically modified potato starches in diets for weanling pigs

We conducted three growth trials to evaluate replacing carbohydrate sources with enzymatically modified potato starches in diets for weanling pigs. In Exp. 1, 180 pigs (initially 5.3 kg and 21+/-2 d of age) were used to compare the effects of corn (36.5%), edible-grade oat flour (36.5%), two enzymatically modified potato starches (12%), and added lactose (12%) on pig performance. Potato Starch 1 had a dextrose equivalent (DE) of 6 and Potato Starch 2 had a DE of 20; both were spray-dried maltodextrans. Pigs that were fed Potato Starch 2 had greater (P<.05) ADG and ADFI than pigs fed diets that contained corn or oat flour from d 0 to 14 after weaning, and pigs fed either Potato Starch 1 or added lactose had intermediate ADG and ADFI. However, for the overall trial (d 0 to 35), no differences (P>.10) in growth performance were observed. In Exp. 2, 198 pigs (initially 4.3 kg and 19+/-2 d of age) were used to determine whether modified Potato Starch 2 could replace a portion of the corn or lactose in the diet. The control diet contained 10% dried whey, and additional treatments were formulated by adding 7 or 14% modified Potato Starch 2 or lactose in place of corn. A positive control diet was formulated containing 29% dried whey. From d 0 to 14 after weaning, increasing dietary lactose improved (linear, P<.04) ADG and ADFI. Increasing the potato starch had no effect on ADG but increased ADFI (linear, P<.02). In Exp. 3, 180 pigs (initially 3.9 kg and 14+/-3 d of age) were used to evaluate Potato Starch 2 or 3 (DE = 30, a spray-dried glucose syrup) as replacements for either corn or lactose in the diet. Pigs were fed a control diet containing 15% dried whey and 12% added lactose. Twelve percent modified Potato Starch 2 or 3 replaced either corn or lactose in the diet on a wt/wt basis. From d 0 to 14 and d 0 to 21, pigs fed either modified potato starch substituted for corn had greater (P<.07) ADG than those fed the control diet. Pigs fed diets with either modified starch substituted for lactose had similar ADG as those fed the control diet. These results suggest that when substituted for corn, Potato Starch 2 can improve growth performance of weanling pigs.     

Quantitative trait loci for honey bee stinging behavior and body size

A study was conducted to identify quantitative trait loci (QTLs) that affect colony-level stinging behavior and individual body size of honey bees. An F1 queen was produced from a cross between a queen of European origin and a drone descended from an African subspecies. Haploid drones from the hybrid queen were individually backcrossed to sister European queens to produce 172 colonies with backcross workers that were evaluated for tendency to sting. Random amplified polymorphic DNA markers were scored from the haploid drone fathers of these colonies. Wings of workers and drones were used as a measure of body size because Africanized bees in the Americas are smaller than European bees. Standard interval mapping and multiple QTL models were used to analyze data. One possible QTL was identified with a significant effect on tendency to sting (LOD 3.57). Four other suggestive QTLs were also observed (about LOD 1.5). Possible QTLs also were identified that affect body size and were unlinked to defensive-behavior QTLs. Two of these were significant (LOD 3.54 and 5.15).     

A quantitative-trait locus on chromosome 6p influences different aspects of developmental dyslexia

Recent application of nonparametric-linkage analysis to reading disability has implicated a putative quantitative-trait locus (QTL) on the short arm of chromosome 6. In the present study, we use QTL methods to evaluate linkage to the 6p25-21.3 region in a sample of 181 sib pairs from 82 nuclear families that were selected on the basis of a dyslexic proband. We have assessed linkage directly for several quantitative measures that should correlate with different components of the phenotype, rather than using a single composite measure or employing categorical definitions of subtypes. Our measures include the traditional IQ/reading discrepancy score, as well as tests of word recognition, irregular-word reading, and nonword reading. Pointwise analysis by means of sib-pair trait differences suggests the presence, in 6p21.3, of a QTL influencing multiple components of dyslexia, in particular the reading of irregular words (P=.0016) and nonwords (P=.0024). A complementary statistical approach involving estimation of variance components supports these findings (irregular words, P=.007; nonwords, P=.0004). Multipoint analyses place the QTL within the D6S422-D6S291 interval, with a peak around markers D6S276 and D6S105 consistently identified by approaches based on trait differences (irregular words, P=.00035; nonwords, P=.0035) and variance components (irregular words, P=.007; nonwords, P=.0038). Our findings indicate that the QTL affects both phonological and orthographic skills and is not specific to phoneme awareness, as has been previously suggested. Further studies will be necessary to obtain a more precise localization of this QTL, which may lead to the isolation of one of the genes involved in developmental dyslexia.     

Concomitant chemoradiotherapy for incompletely resected supratentorial low-grade astrocytoma in children: preliminary report

Interval mapping was used to identify putative quantitative trait loci (QTL) for blood pressure and cardiac mass on Chromosome (Chr) 3 in F1(S x R) x S population of 150 rats raised on an 8% NaCl diet. Two genetic markers 95.7 cM apart, D3Wox3 and D3Mco5 (tightly linked to Edn3), showed "suggestive" linkage to blood pressure (LOD = 2.0 and 1.8 respectively). In addition, D3Wox3 showed "suggestive" linkage to heart weight (LOD = 2.5), and D3Mco5 showed "suggestive" linkage to body weight-adjusted heart weight (LOD = 2.1). Congenic rats (designated S.R-Edn3) were constructed by introgressing the R-rat Edn3 allele (and flanking loci) into the S strain. On a 2% NaCl diet, S.R-Edn3 rats had lower blood pressure (21.4 mm Hg, P = 0. 0005) and heart weight (59 mg, P = 0.0038) compared with S rats, confirming the existence of a blood pressure QTL on Chr 3 near Edn3 even though QTL linkage analysis of blood pressure did not achieve stringent statistical criteria for significance. The results of the congenic experiment and the large distance between the two putative QTL suggest the presence of at least two independent blood pressure/cardiac mass QTL detectable on Chr 3 in the Dahl rat model of genetic hypertension.     

Effect of duration of feed quality restriction on body dimensions in lambs

We measured the effect of duration of feed quality restriction and the consequent compensatory growth on body dimensions in 18 crossbred Swifter (Texel sire x Flemish dam) male lambs born in March 1994 and weaned at approximately 2 mo of age. The lambs were fed grass straw (46 g CP/kg DM) for ad libitum consumption and 35 g CP x kg(-75) x d(-1) mixed concentrates (173 g/kg DM). At approximately 3.5 mo of age and average live weight of approximately 34 kg, the lambs were allotted to six blocks, each block with three lambs of approximately the same live weight. Within each block, the three lambs were then randomly assigned to two restricted treatments (R1 and R2) and a control (C) treatment. In treatments R1 and R2, feed quality was restricted by withholding concentrates for 3 and 4.5 mo, respectively. A growth model was developed to study the effects of restriction and subsequent compensation after realimentation (6.5 and 8 mo for R1 and R2 groups, respectively). During restriction, live weight and growth in body dimensions were suppressed. Bone length measures such as body length and ulna length were less affected than live weight. The response in testes girth to restriction was almost immediate. At the end of the experiment (age of about 14 mo), R1 animals fully compensated. However, the R1 animals had higher testes girth (P < .001), chest girth (P < .01), and chest depth (P < .05). Extending the duration of feed restriction did not have a significant effect on the rate of losses in live weight and body dimensions during restriction. At the end of the experiment, except for withers height and trunk length, the R2 animals did not compensate fully in live weight and other dimensions. However, the parameter estimates suggested that the R2 animals may need a relatively longer period of realimentation to reach to the same size as R1 and C animals.     

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.     

Magnetic resonance imaging and invasive evaluation of development of heart failure in transgenic mice with myocardial expression of tumor necrosis factor-alpha

The intestine is a large endocrine organ, but the dependence of colon cancer on hormones remains unknown. We show here that neurotensin, a paracrine/endocrine peptide in the gut, and the neurotensin receptor antagonist SR 48692 control colon cancer cell growth in vitro and in vivo by interacting with receptors that are ectopically expressed in colon cancers. In cell culture, neurotensin stimulates the growth of human colon cancer cell lines (SW480, SW620, HT29, HCT116 and Cl.19A) expressing the neurotensin receptor NTR1 but does not change the growth of Caco2 cells, which do not express NTR1. In SW480 cells, neurotensin is active in the 10(-10) to 10(-6) M concentration range (ED50 = 0.47 nM) while the neurotensin fragment (I-II) is inactive. Neurotensin also enhances the cellular cloning efficiency of SW480 cells in soft agar by inducing a 50% increase of colony formation. This effect is blocked by SR 48692, which alone does not alter colony formation. Subcutaneous delivery of neurotensin (0.54 micromol/kg every 24 hr) by osmotic pumps to nude mice that have been xenografted with SW480 cells results in a significant increase of tumor volume, i.e., up to 255% of control at day 20 of treatment. SR 48692 administered alone (1.7 micromol/kg every 24 hr) by daily i.p. injections reduces the development of tumors formed by xenografting SW480 cells in nude mice. A significant mean reduction of tumor volume of 38% is observed during the 22-day period of treatment. SR 48692 alone is also active at reducing tumor volume after xenografting HCT116 cells in nude mice. Our results support the notion that colon cancer growth may be dependent on blood-borne neurotensin and suggest that non-peptide neurotensin antagonists, such as SR 48692, may be useful for the development of novel therapeutic strategies of colon cancer.     

Body composition and metabolic profiles associated with puberty in beef heifers

Rapid growth large frame (RL, n = 61) or average growth medium frame (AM, n = 71) biotype heifers fed to achieve either moderate (MOD, .6 kg/d) or high ADG (HI, 1.0 kg/d) were used to determine whether puberty occurs at similar body composition or metabolic status. A heifer was considered pubertal after being detected in estrus and then forming a functional corpus luteum. Live animal estimates of body composition and blood samples for assessment of metabolic status were taken at 13 +/- .2 d after estrus for all heifers. Body composition and metabolic status were assessed every 56 d from 7 mo of age until puberty in a subset of 80 heifers representing all biotype-diet combinations. At puberty, 32 of these 80 heifers were slaughtered and physical and chemical composition of the empty body were determined. High-gain diet heifers were younger, heavier, taller, and more muscular (all P < .01) at puberty than MOD heifers. Slaughter measurements paralleled live animal estimates; bodies of HI and RL heifers contained more (P < .01) carcass and noncarcass components than those of MOD and AM heifers, respectively. Carcasses of RL and HI heifers were more (P < .05) muscular and fatter than AM and MOD heifers. At puberty, HI heifers had a greater (P < .01) mass of moisture, fat, and fat-free organic matter (FFOM) than MOD, whereas RL heifers had more moisture, ash, and FFOM than AM. Percentage of fat was greater (22.1 +/- 1.0 vs 1.0 vs 19.1 +/- 1.0; P < .05) and percentage of moisture was less (55.4 +/- .6 vs 58.1 +/- .6; P < .01) in bodies of HI than in those of MOD heifers. Concentrations of blood urea nitrogen and insulin were greater (P < .05) in HI than in MOD heifers. Diet did not influence concentration of IGF-I or glucose, and metabolic markers were unaffected by biotype. No dramatic changes in body composition or metabolic signals were detected before puberty. Puberty did not occur at similar body composition or metabolic status in all heifers.