Cognitive-behavioral group intervention to assist substance-dependent adolescents in lowering HIV infection risk.

Substance dependent adolescents (N = 19), court referred into a residential drug treatment facility received a five-session HIV risk-reduction intervention that provided risk education, social competency skills (sexual assertion, partner negotiation, and communication skills), technical skills (condom use), and problem-solving training. Before and after the intervention, subjects completed measures of AIDS risk knowledge, health locus of control, social support, attitudes toward HIV prevention, attitudes toward condoms, self-efficacy, and perceptions of risk in addition to role-play assessments of behavioral skill resisting high-risk coercions. Postintervention, subjects exhibited increased knowledge about HIV/AIDS, more favorable attitudes toward prevention, greater internal and lower external locus of control scores, more favorable attitudes toward condom use, increased self-efficacy, and greater recognition of HIV vulnerability. Following intervention, the percentage of participants reporting sexual activity in high-risk contexts decreased, substantiating the intervention's effectiveness. Self-report data were corroborated by sexually transmitted disease treatment records. This uncontrolled demonstration effort suggests that skills training based on cognitive-behavioral principles may be a promising intervention strategy to lower vulnerable adolescents' risk of HIV infection.

Influence of the beta 2-adrenergic agonist clenbuterol on insulin-stimulated lipogenesis in mouse adipocytes.

Growing mice fed the beta 2-adrenergic agonist clenbuterol (CB; 20ppm) had increased rate of growth and altered composition of gain (greater protein and less fat). Adipocytes prepared from the epididymal fat pads of treated and untreated mice were used to examine the influence of CB on lipid metabolism. Using cells from untreated mice, CB stimulated lipolysis to an equivalent maximum rate as epinephrine (EPI), but CB was far less potent (EC50 (microM); CB = 5, EPI = 0.2). Both CB and EPI inhibited insulin-stimulated lipogenesis over the physiological range of insulin concentrations. This inhibition was expressed as a dose-dependent decrease in tissue sensitivity to insulin and a decrease in maximal lipogenic capacity. Inhibition of maximal rate, but not of insulin sensitivity, could be stimulated by the addition of palmitate without EPI or CB. Adipocytes isolated from CB-treated mice did not differ from controls in sensitivity to insulin or in activity of fatty acid synthetase. Increased lipolysis and reduced lipogenesis as observed in vitro with CB are consistent with reduced fat accretion in CB-treated mice. However, the absence of detectable changes in adipocyte lipogenesis from CB-fed mice leaves open the question of the relevance of altered lipid metabolism to the observed changes in body composition.

Influence of sulfate in drinking water on mouse reproduction during two parities.

Field studies have suggested that high levels of sulfate in drinking water may alter water consumption and have an adverse effect on animal reproduction. This study was conducted to determine whether sulfate in the drinking water affects the reproductive performance of female mice during gestation and lactation over two parities. Sixty random-bred albino mice were randomly assigned to six sulfate treatments. Sodium sulfate was added to deionized distilled water to give sulfate levels in ppm as follows: (1) 0 (control); (2) 0 (Na control); (3) 625; (4) 1,250; (5) 2,500 and (6) 5,000. Treatments 2 to 6 contained the same Na content (2,392 ppm) by varying Na bicarbonate content. Mice receiving only the deionized distilled water drank less (P less than .05) than mice receiving the other treatments at all times measured. Animals offered the 0 (Na control) water drank more (P less than .05) water than mice on the other sulfate treatments. There was no difference (P greater than .10) in litter size, litter weaning weight, or gestational and lactational weight gain of the dam among water treatments. Although levels of sulfate up to 5,000 ppm and 2,392 ppm Na in the drinking water cubicly altered water consumption, they did not affect litter size, litter weaning weight, or gestational and lactational weight gain of the dam when sulfate ingestion was continued over two parities.

Nitrogen utilization and lean growth performance of 20- to 50-kilogram pigs fed diets balanced for lysine:energy ratio.

Two experiments were conducted to determine the lysine:DE ratio that would maximize nitrogen retention and lean growth in growing pigs. Diets were formulated to contain 2.5, 3.0, 3.5, or 4.0 g of lysine/Mcal of DE at 3.5 and 3.75 Mcal of DE/kg of diet arranged in a 4 x 2 factorial. Experiment 1 used 48, 20-kg crossbred barrows in a nitrogen balance study. Feeding diets containing 3.75 Mcal of DE/kg of diet resulted in higher (P < .01) nitrogen digestibility and retention as well as higher energy and DM digestibility. In diets containing 3.5 Mcal of DE/kg, increasing the lysine:DE ratio had no effect on nitrogen retention, but an increase up to 3.0 g of lysine/Mcal of DE was observed at the 3.75 Mcal of DE level. In Exp. 2, 96 individually housed growing crossbred barrows and gilts were used to determine lean and growth performance to the diets fed in Exp. 1 in a 4 x 2 x 2 factorial arrangement of treatments. Weight gain was unaffected by dietary treatment. A reduction (P < .01) in feed intake and an improvement (P < .05) in feed efficiency was observed as the DE level increased. Increasing the lysine:DE ratio to 3.0 to 3.5 g of lysine/Mcal of DE increased (P < .05) the rate of fat-free lean and empty body protein gain and the weight of fat-free lean at 50.9 kg increased (P < .01) with increasing lysine:DE ratio regardless of sex or energy level.(ABSTRACT TRUNCATED AT 250 WORDS)

Availability of amino acids for 10- to 20-kilogram pigs: lysine and threonine in soybean meal.

The availabilities of lysine and threonine in soybean meal for 10- to 20-kg pigs were determined in two experiments using slope-ratio methodology. In the first experiment, a basal diet formulated to contain 6 g of lysine/kg, but adequate in all other amino acids, was supplemented with 1, 2, or 3 g of lysine/kg from either soybean meal or L-lysine-HCl. Each of the seven diets was available on an ad libitum basis to six individually penned pigs (barrows:gilts, 1:1) from an initial weight of 9.9 kg until they reached a live weight of 20.8 kg. Daily feed intake was similar among diets. Common-intercept multiple linear regression of daily live weight gain and gain:feed ratio on dietary lysine level indicate slope ratios (soybean meal:lysine.HCl) of .85 and .88, respectively. In Exp. 2, a basal diet formulated to contain 4 g of threonine/kg was supplemented with .65, 1.30, 1.95, or 2.60 g of threonine/kg from either soybean meal or L-threonine. Each of the nine diets was available on an ad libitum basis to six individually penned pigs (barrows:gilts, 1:1) from 9.9 to 21.0 kg live weight. As in Exp. 1, daily feed intake was similar among the nine diets. The slope ratios (soybean meal:L-threonine) from common-intercept multiple regression analyses were .73 and .78 for daily weight gain and gain:feed ratio, respectively. Thus, the availabilities of lysine and threonine in soybean meal for young pigs were estimated to be 85 to 88% and 73 to 78%, respectively.

Effects of dietary levels of selenium-enriched yeast and sodium selenite as selenium sources fed to growing-finishing pigs on performance, tissue selenium, serum glutathione peroxidase activity, carcass characteristics, and loin quality.

This research evaluated the efficacy of inorganic and organic Se sources for growing-finishing pigs, as measured by performance and various tissue, serum, carcass, and loin quality traits. A total of 351 crossbred pigs were allotted at an average BW of 20.4 kg to six replicates of a 2x4 factorial experiment in a randomized complete block design. Pigs were fed diets containing Se-enriched yeast (organic) or sodium selenite (inorganic), each at .05, .10, .20, or .30 mg Se/kg diet. A non-Se-fortified basal diet was a ninth treatment group. Five pigs per pen were bled initially and at 30-d intervals with serum analyzed for Se and glutathione peroxidase (GSH-Px) activity. At 55 kg BW, one pig per pen from each of three replicates was killed, and tissues were collected for Se analysis. At 105 kg BW, the remaining pigs in the three replicates were killed, carcass measurements were collected, tissues were analyzed for Se, and loin quality was evaluated for pH, drip loss, and lightness. No performance or carcass measurement benefit resulted from either Se source or dietary Se levels. Pigs had a lower serum Se concentration and GSH-Px activity when the basal diet was fed, but both increased as dietary Se level increased (P<.01). Serum GSH-Px activities were increased by pig age and reached a plateau when the diet contained approximately .10 mg Se/kg (P<.01) at d 30, and 60 of the trial, and at .05 mg Se/kg diet at d 90 of the trial. The organic Se group fed .05 and .10 mg Se/kg had serum GSH-Px activities that tended to be lower than those of pigs fed the inorganic Se source, but GSH-Px activities in both groups were similar at higher Se levels. Tissue Se contents increased linearly as the dietary Se level increased, but the increase was markedly higher when organic Se was fed, resulting in an interaction (P<.01) response. Loin drip loss, pH, and lightness were unaffected (P>.15) by organic Se source or level, but there was a trend for a higher drip loss (P = .11) and a linear (P<.01) increase in loin paleness when the inorganic Se level increased. These results indicate that neither Se source nor Se level had an effect on pig performance or carcass measurements, but organic Se source increased tissue Se concentrations. Inorganic Se may, however, have a detrimental effect on loin quality, as reflected by higher drip loss and a paler color. Using serum GSH-Px activity as the measurement criterion, the supplemental dietary Se requirement did not seem to exceed .10 and .05 mg Se/kg diet for the growing and finishing phases, respectively, when added to a basal diet containing .06 mg Se/kg.

The effect of an adaptation period to soybean oil additions in the diets of young pigs.

Utilization of soybean oil (SBO) in swine starter diets and the effect of an adaptation period to SBO on performance was studied in two 4-wk experiments with pigs initially 4 to 5 wk of age. One trial was extended an additional 4 wk and apparent DE was measured during the 4th wk postweaning. Corn-soybean meal-based diets were used in which SBO was substituted for cornstarch at 2, 4 and 6% of the diet in Exp. 1 and at 3 and 6% of the diet in Exp. 2. In Exp. 2, SBO was added either initially (adaptation) or after 2 wk (no adaptation). In Exp. 1 daily gain and efficiency of feed utilization were improved (P less than .05) by adding SBO during wk 3 and 4, but not earlier. Feed intake was not affected by treatment. In Exp. 2, for the initial 4-wk postweaning period, there was no effect of SBO addition on growth rate; feed intake was depressed (P less than .05) when SBO was added at wk 3, and efficiency of feed utilization was improved (P less than .05) for pigs fed SBO without an adaptation period. The primary improvements in performance occurred in the 3rd and 4th wk postweaning, with a tendency for pigs to perform better without an adaptation period. During wk 4, pigs adapted to SBO consumed more (P less than .05) feed but tended to be less efficient (P less than .10) than nonadapted pigs. With or without adaptation, apparent DE was unaffected by SBO additions. Regardless of adaptation period, SBO additions depressed feed intake (P less than .05) and improved efficiency of feed utilization (P less than .01) for the 5- to 8-wk growing phase. In conclusion, adding SBO the first 2 wk postweaning did not improve performance; an adaptation period was not necessary for a performance response from added SBO.

Changes in pars esophageal tissue appearance of the porcine stomach in response to transportation, feed deprivation, and diet composition.

Experiment 1 used 48 pigs to evaluate the effect of diet particle size, fat content, and a 24-h fast (FST) on pars esophageal (PE) tissue damage. Following a FST, a 750-microm, 550-microm, or 550-microm diet with 7.9% added fat was fed for 28 d. Additional pigs were fed the 550-microm fat-added diet with a FST every 7 d. The initial FST induced erosion (EROS) of the PE (P < .05). A 550-microm diet maintained the FST-induced EROS (P < .05). The 750-microm diet allowed the PE to heal. Sixteen pigs were used in Exp. 2 to evaluate transportation and FST-induced changes in PE. A FST following transportation induced keratinization (KERT) and EROS of the PE (P < .05). In Exp. 3, restraint and a FST followed by a 750-microm diet on PE was investigated using 48 pigs. A FST induced PE KERT and EROS, which was reduced to pre-FST levels ( P < .05) within 3 to 14 d by a 750-microm diet. In Exp. 4, 70 pigs were fed 750-microm or 550-microm diets following transportation and subsequent FST. Within 7 d, healing (P < .05) of FST-induced PE damage was observed with a 750-microm diet. A 550-microm diet maintained (P < .05) the transportation/FST-induced PE damage. Thirty pigs were used in Exp. 5 to investigate the effect of restraint for 24 h and FST on PE. A FST and the combination of restraint and FST induced similar levels of PE damage that were greater than pre-restraint/FST levels (P < .05).

Phytase-induced changes in mineral utilization in zinc-supplemented diets for pigs.

Forty-eight pigs (barrows:gilts, 1:1) with an average initial weight of 9.4 kg were used in a 2 x 2 factorial experiment to determine the influence of dietary phytase (0 or 1,500 phytase units/kg) and zinc (0 or 100 mg/kg) supplementation of a corn-soybean meal diet on the utilization of P, Ca, Cu, Mg, Mn, and Zn. After a 21-d growth experiment, feed was withheld for 24 h and blood was collected from the anterior vena cava of all pigs for plasma mineral analyses. Twenty-four barrows from the growth experiment were then placed in metabolism cages and used in an 8-d mineral balance study. All pigs were maintained on their previous diet. Growth rate was fastest (P < .05) and feed efficiency was highest (P < .05) for pigs fed phytase-supplemented diets. Feed intake was unaffected (P > .05) by dietary treatment. Plasma P (P < .01) and Mg (P < .05) concentrations increased with phytase addition. Plasma Zn concentration increased (P < .05) when phytase was added to the diet containing no supplemental Zn, but plasma Zn concentration was not affected (P > .05) by phytase when the diet was supplemented with 100 mg of Zn/kg. Apparent Ca, P, and Cu balance were improved (P < .05) with phytase addition; however, Cu balance was reduced (P < .05) by Zn supplementation. Zinc balance was increased (P < .05) with supplemental zinc and phytase in the diet. These results indicate that the growth-promoting effect of phytase may be due to an overall increase in the availability of minerals.

The impact of ractopamine, energy intake, and dietary fat on finisher pig growth performance and carcass merit.

An experiment was conducted to determine the effect of ractopamine, energy intake, dietary fat level, and sex on performance and carcass composition in finishing pigs. Three hundred six barrows and gilts were used in a factorial arrangement of treatments replicated over three seasons. Treatments consisted of two ractopamine levels (0 vs 44.7 mg/d), two sexes (barrows and gilts), two levels of fat addition (0 vs 5% added fat), and four energy intake levels (8.3, 8.9, 9.5, and 10.1 Mcal of ME/d for barrows and 7.7, 8.3, 8.9, and 9.5 Mcal of ME/d for gilts). Diets were formulated to maintain an equal lysine (28.5 g/d) intake at each feeding level through cornstarch dilution of the basal (7.7 Mcal of ME/d) diets. Pigs were fed daily based on a standard feed intake curve and prior weekly body weights. At slaughter (104 kg), carcass measurements and TOBEC HA-1 scanner measurements were recorded. Dietary fat addition improved live weight and lean efficiency (grams of carcass lean gain/kilogram of feed, P < .05). Dietary fat addition did not affect growth rate or carcass composition. Increasing energy intake resulted in a linear increase in average daily gain for both barrows and gilts (P < .01). Dietary ractopamine influenced the response of lean tissue accretion, lean tissue accretion efficiency, and fat tissue accretion to energy intake. Pigs with no added ractopamine demonstrated increased lean tissue accretion and improved efficiency and decreased fat tissue accretion with increasing energy intake (up to 9.5 Mcal of ME intake for barrows and 8.9 Mcal of ME intake for gilts). In contrast, pigs with added ractopamine did not respond to increasing energy intake and demonstrated increased fat tissue accretion with increasing energy intake. The response to ractopamine for growth was greatest from d 6 to 22 on test or during the test gain period of 7 to 18 kg. After d 22, the response of ractopamine declined linearly. These results indicate that ractopamine increases growth rapidly at the onset of feeding until a plateau is reached, after which there is a linear decline in growth response.

Influence of daily injections of porcine somatotropin on growth, puberty, and reproduction in gilts.

To determine whether recombinant porcine somatotropin (rpST) alters reproduction, 40 crossbred gilts weighing 59.1 +/- .5 kg at 125 +/- 1 d of age were assigned randomly to an experiment arranged as a 2 x 2 factorial. Eight gilts were given daily injections of diluent until they reached 104 kg BW (DW), and eight received diluent injections until puberty (DP). Twelve gilts were given rpST (4 mg/d) until 104 kg BW (PW) and 12 were given rpST injections until puberty (PP). All gilts were individually fed on an ad libitum basis an 18% CP corn-soybean meal diet (1.2% lysine and 3.1 Mcal/kg of ME). Beginning at 5 mo of age, gilts were exposed 20 min daily to mature boars. Serum concentrations of progesterone were measured weekly from 5 to 8 mo of age to verify age of puberty. Gilts observed in pubertal estrus were mated to two different boars 10 h apart. At 47 +/- 1 d of gestation, gilts were slaughtered to assess fetal development. After 60 d of treatment, serum LH and FSH profiles were determined in blood samples drawn at 20-min intervals for 4 h from eight diluent- and eight rpST-treated gilts fitted with indwelling jugular catheters. By 28 d, feed intake, feed/gain, and blood urea nitrogen were decreased (P less than .005) by rpST. Treatments did not affect (P greater than .05) the proportion of gilts attaining first ovulation (DW = 6/6; DP = 10/10; PW = 7/9; PP = 14/14) or conception rate (DW = 5/6; DP = 7/10; PW = 4/6; PP = 11/12).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of efrotomycin on gain and feed efficiency for pigs from weaning until market weight.

Six studies involving 700 pigs were conducted in five separate swine research facilities to evaluate weight gain and efficiency of feed utilization in pigs fed the antibiotic efrotomycin. Pigs averaging 8.4 kg at the beginning of the studies were fed fortified corn-soybean meal diets that contained efrotomycin at 0, 2, 4, 8 or 16 ppm for an average of 120 d to market weight, about 92.1 kg. Pigs fed efrotomycin gained 5.9 to 8.9% faster (P less than .01) and were 1.7 to 4.0% more efficient (P less than .01) than those fed control diets. The improvement in growth rate was linear from 2 through 16 ppm, while feed efficiency (gain/feed) plateaued at 4 ppm efrotomycin. Treatment X study interactions were not significant for average daily gain or feed efficiency, showing that the response to efrotomycin was similar in each study. These studies indicate that efrotomycin is effective in improving gain and efficiency of feed utilization in swine from weaning until market weight.

Influence of porcine somatotropin on endocrine and histological variables in gilts.

Thirty-six crossbred gilts (71.7 +/- .9 kg and 140.1 +/- .9 d) were assigned to one of three doses (0, 35, or 70 micrograms.kg BW-1 x d-1) of recombinant porcine somatotropin (rpST). The doses of rpST were adjusted weekly, and i.m. injections continued until d 50. Gilts were pen fed (six gilts/pen) a 17% CP corn-soybean diet (1.2% lysine and 3.2 Mcal of ME/kg). At d 50, feed intake, feed:gain ratios (P = .02), and blood urea nitrogen were decreased (P < .001) by increasing rpST doses, whereas ADG was increased (P = .04) by increasing rpST doses. Injections of rpST did not affect (P > .05) conception rate, age, or weight at puberty. Numbers of blastocysts or corpora lutea observed at d 10.4 +/- 1.5 of gestation (42.2 d after final rpST injection) were unaffected (P > .05) by rpST treatment. Anterior and posterior pituitary weights were increased (P < or = .003) linearly with rpST dose. However, liver, adrenal, and heart weights were unaffected (P > .05) by rpST. After a withdrawal period of 42.2 +/- 2.0 d, rpST increased (P < or = .02) the estimated percentage of lean by 5.8% and longissimus muscle area by 10.4%. Eighteen hours before the initial rpST injection (d 0), 10 gilts per rpST dose were catheterized. Catheterizations were repeated on d 40. The rpST or diluent was given i.m. in the extensor muscle of the neck 1 h after initiation of blood collection. Adrenocorticotropic hormone (1.4 IU/kg BW) was administered through the catheter 3 h after initiation of blood collection.(ABSTRACT TRUNCATED AT 250 WORDS)

Further assessment of the dietary lysine requirement of finishing gilts.

A cooperative research study involving 635 gilts was conducted at eight research stations to further estimate the lysine requirement of finishing gilts. Dietary crude protein levels of the five dietary treatments ranged from 16.0 to 24.4% with calculated lysine levels of .80, .95, 1.10, 1.25, or 1.40%. Each station contributed a minimum of two replicate pens of pigs per treatment. Average initial and final weights were 53.6 and 116.4 kg, respectively. At the end of the experimental period, pigs were killed and hot carcass weight, 10th-rib fat depth, and longissimus muscle area were measured. Carcass fat-free lean percentage and fat-free lean gain were estimated from these data. Daily lysine intakes averaged 21.8, 25.9, 30.5, 34.3, and 37.8 g/d for the five treatment groups, respectively. Increasing the dietary lysine from .80 to .95% numerically increased weight gain and gain:feed, but these increases were not maintained at higher levels of dietary lysine. Overall, rate and efficiency of gain decreased (cubic, P < .01) with increasing dietary lysine. Carcasses were leaner at the two higher levels of dietary lysine as evidenced by reduced 10th rib backfat (linear, P < .01), increased longissimus area (quadratic, P < .04), and increased percentage of estimated fat-free lean (linear, P < .01). Carcass fat-free lean gain was not influenced by dietary lysine except for a small numerical improvement (P < .11) at the .95% level of dietary lysine that paralleled the improvement in body weight gain. The results indicate that the dietary lysine requirement of finishing gilts with a mean carcass fat-free lean growth rate of 306 g/d from 54 to 116 kg body weight is probably no higher than .80% of the diet to achieve maximum rate and efficiency of body weight gain and carcass lean growth rate. The results also indicate that higher dietary lysine levels may increase carcass leanness in finishing gilts, possibly due to reduced intake of NE. Whether this response is due to the effects of lysine alone, protein (i.e., other amino acids), or soybean meal is unknown.

The dietary protein and(or) lysine requirements of barrows and gilts. NCR-42 Committee on Swine Nutrition.

A cooperative research study involving three experiments and 2,318 pigs was conducted at 12 research stations to evaluate the protein (lysine) requirements of barrows and gilts. The two sexes were penned separately and fed fortified corn-soybean meal diets containing protein levels ranging from 12.0 to 17.2%. Lysine levels in these diets ranged from .52 to .90%. Protein levels in Exp. 1 were 12, 14, and 16%; in Exp. 2, protein levels were 13, 14, 15, and 16%; and in Exp. 3, they were 13.2 15.2, and 17.2%. Fat (5%) was added to one-half of the diets in Exp. 3. Each station that participated contributed a minimum of two replicate pens of pigs per diet-sex combination in a given experiment. Average initial and final weights were 35 and 99 kg in Exp. 1 and 51 and 105 kg in Exp. 2 and 3, respectively. At the end of the test period, pigs were slaughtered and hot carcass weight, 10th rib fat depth, and longissimus muscle area were measured. Percentage of carcass muscle was estimated from these data. Overall, barrows gained weight faster than gilts (P < .01), but gilts required less feed per unit of gain (P < .05) and had less backfat, larger longissimus muscle areas, and a greater percentage of carcass muscle (P < .01) than did barrows. Lean growth rate was similar for barrows and gilts (332 vs 329 g/d). Increasing the dietary protein or lysine level resulted in improved rate and efficiency of gain and increased carcass leanness and lean growth rate in gilts, but the increase was less pronounced or did not occur in barrows, resulting in protein level x sex interactions. Feeding low-protein (12 or 13%) diets decreased performance and carcass leanness to a greater extent in gilts than in barrows. The pooled data from the three experiments indicated that most traits tended to reach a plateau at 13% CP (.60% lysine) in barrows, whereas in gilts, weight gains, feed/gain, carcass muscle, and lean growth rate continued to improve, but at a decreasing rate, with up to 17.2% CP (.90% lysine). The results indicate that gilts require higher concentrations of dietary amino acids to maximize lean growth rate than do barrows.

The performance and carcass composition responses of finishing swine to a range of porcine somatotropin doses in a 1-week delivery system.

Four experiments using 580 barrows and 580 gilts (Study 1) and seven experiments using 500 barrows and 500 gilts (Study 2) were conducted at various geographical locations in the United States to determine the dose response of a pelleted form of porcine somatotropin (pST) relative to ADG, feed/gain (F/G), and percentage of carcass protein. Average initial weights for Studies 1 and 2 were 67.6 and 72.6 kg, respectively, and four pigs/pen were slaughtered when they achieved weights of 106.5 to 111.0 kg. In Study 1, pigs were implanted subcutaneously with pelleted pST doses of 0, 12, 24, 36, or 48 mg/wk and self-fed a corn-soybean meal diet containing 13.75% CP. Study 2 included two control groups self-fed a diet containing either 13.75 or 17% CP with added lysine. The pST-treated pigs were administered 12, 24, or 36 mg/wk, and all were offered the 17% CP diet. The pST treatments in Study 1 resulted in a linear reduction (P less than .05) in average daily feed intake (ADFI) and a quadratic (P less than .05) improvement in F/G and percentage of carcass protein. The pST treatments in Study 2 resulted in a linear reduction in ADFI (P less than .05), a linear improvement in F/G, and a quadratic increase in the percentage of carcass protein (P less than .05). Average daily gain was not affected in either study with this form of pST. The greatest increase in efficiency of lean gain was observed with the 36-mg dose for both Study 1 (9.4%) and Study 2 (10.8%). In Study 1, the force required to shear cores of the longissimus muscle was increased linearly with pST treatment (P less than .05). There was a similar linear increase in Study 2 with pST treatment (P less than .05); however, there was also an effect of sex (P less than .05) on shear force (gilts greater than barrows) that was similar in magnitude to that observed for pST treatment. Differences in sensory evaluation because of pST were minor and of the same magnitude as those observed between barrows and gilts. It was therefore concluded that weekly administration of pST improved F/G and percentage of carcass protein with no detrimental effects on palatability of cooked lean pork.

Variability among sources and laboratories in analyses of wheat middlings. NCR-42 Committee on Swine Nutrition.

A cooperative research study was conducted by members of a regional committee (North Central Regional Committee on Swine Nutrition [NCR-42]) to assess the variability in nutrient composition (DM, CP, Ca, P, Se, NDF, and amino acids) of 14 sources of wheat middlings from 13 states (mostly in the Midwest). A second objective was to assess the analytical variability in nutrient assays among 20 laboratories (labs; 14 experiment station labs and six commercial labs). Wheat middlings were obtained from each participating station's feed mill. The bulk density of the middlings ranged from 289 to 365 g/L. The number of labs that analyzed samples were as follows: DM and CP, 20; Ca, 16; P, 15; Se, 7; NDF, 10; and amino acids, 9. Each lab used its own analytical procedures. The middlings averaged 89.6% DM, 16.2% CP, .12% Ca, .97% P, 36.9% NDF, .53 mg/kg Se, .66% lysine, .19% tryptophan, .54% threonine, .25% methionine, .34% cystine, .50% isoleucine, and .73% valine. As expected, there was considerable variation in nutrient composition among the 14 sources (P < .01), especially for Ca (.08 to .30%) and Se (.05 to 1.07 mg/kg). "Heavy" middlings (high bulk density, >335 g/L), having a greater proportion of flour attached to the bran, were lower in CP, lysine, P, and NDF than "light" middlings (<310 g/L), having cleaner bran, resulting in negative correlations between bulk density and CP (r = -.61), lysine (r = -.59), P (r = -.54), and NDF (r = -.81). Each 1-percentage-point increase in CP in the wheat middlings was associated with .0235 (r2 = .61) and 2.1 (r2 = .39)-percentage-point increases in lysine and NDF, respectively. Lysine content was associated with NDF, CP, and bulk density of wheat middlings (r2 = .88). There was considerable variation among laboratories (P < .01) in analysis of all nutrients. The CV among sources (100 x sigmaS/mean) was greater than among labs (100 x sigmaL/mean) for CP, Ca, P, Se, and NDF, but the CV among labs was greater than that among sources for DM and all of the amino acids except lysine and phenylalanine.

Variability among sources and laboratories in nutrient analyses of corn and soybean meal. NCR-42 Committee on Swine Nutrition. North Central Regional-42.

A cooperative research study involving members of a regional committee (North Central Regional Committee on Swine Nutrition [NCR-42]) was conducted to assess the variability in nutrient composition (DM, CP, Ca, P, Se, and amino acids) of corn and soybean meal from 16 sources (15 states, mostly in the Midwest) and to assess the analytical variability in nutrient assays among 22 laboratories (labs; 16 experiment station labs and six commercial labs). Corn samples were obtained from each participating station's feed mill during a 3-yr period (1989, 1990, and 1992), as were soybean meal samples during a 2-yr period (1989 and 1990). Both regular soybean meal (with hulls) and dehulled soybean meal were represented in the study. Samples were analyzed for DM and CP by all 22 labs, for Ca and P by 15 labs, for amino acids by 10 labs, and for Se by 6 labs. Each lab used its own analytical procedures. Samples of corn and soybean meal varied in their nutrient composition depending on the area of origin. The greatest variation among sources was in Se concentration, ranging from .02 to .29 mg/kg in corn and .08 to .95 mg/kg in soybean meal. Crude protein and lysine in corn were positively correlated, but the regression coefficient was low (r2 = .49). The relationship between CP and lysine for the two soybean meals combined was considerably stronger (r2 = .81). Lysine in corn increased by .018 percentage point and lysine in soybean meal (regular and dehulled combined) increased by .063 percentage point for each 1 percentage point increase in CP. Except for CP and Se, the analytical variability among labs was as great as, and in some cases greater than, the variability in nutrient composition among sources of corn and soybean meal. Within-lab analytical variability tended to be less than among-lab variability. Some labs performed certain analyses with considerably less variability and more accuracy than others.

Variability in mixing efficiency and laboratory analyses of a common diet mixed at 25 experiment stations.

An experiment involving 25 experiment stations in the North Central and Southern regions (NCR-42 and S-288, respectively) was conducted to assess the degree of uniformity of diet mixing among stations and to assess the variability among station laboratories in chemical analysis of mixed diets. A fortified corn-soybean meal diet was mixed at each station using a common diet formula (except for vitamin and trace-mineral additions). The diet was calculated to contain 14% crude protein (CP), 0.65% Ca, 0.50% P, and 125 ppm Zn (based on 100 ppm added Zn). After mixing, samples were collected from the initial 5% of feed discharged from the mixer, after 25, 50, and 75% was discharged, and from the final 5% of discharged feed. The five samples were sent to the University of Kentucky, finely ground, and divided into subsamples. Each set of five subsamples from each station was distributed to three randomly selected stations for analysis of CP, Ca, P, and Zn (i.e., each station analyzed five diet sub-samples from three other stations). In addition, two commercial and two station laboratories analyzed composites of the five subsamples from each of the 25 mixed diets. Based on the laboratories that analyzed all diets, means were 13.5, 0.65, and 0.52%, and 115 ppm for CP, Ca, P, and Zn, respectively. Ranges of 11.8 to 14.6% CP, 0.52 to 0.85% Ca, 0.47 to 0.58% P, and 71 to 182 ppm of Zn were found among the 25 diet mixes. The coefficients of variation among the 25 diet samples for CP, Ca, P, and Zn were 4.3, 9.3, 4.1, and 17.4%, and among the 25 laboratories were 3.6, 12.5, 10.7, and 11.1%, respectively. Overall analyses of the five sub samples were, respectively, CP: 13.4, 13.6, 13.4, 13.5, and 13.4% (P < 0.06); Ca: 0.66, 0.67, 0.67, 0.66, and 0.67%; P: 0.50,0.51,0.51,0.50, and 0.50%; and Zn: 115, 116, 112, 113, and 120 ppm (P < 0.001). Diets were not uniformly mixed at all stations (station x sample No. was P < 0.08 for Ca and P < 0.01 for CP, P, and Zn). Among stations, the range of the five samples, expressed as a percentage of the mean and averaged for CP, Ca, P, and Zn, varied from +/- 1.1% (i.e., 98.9 to 101.0%) to +/- 12.9% (84.6 to 110.4%), with an overall average of +/- 5.2%. Neither type nor volume of mixers was related to mixing uniformity. The results suggest that uniformity of diet mixes varies among experiment stations, that some stations miss their targeted levels of nutrients (especially Zn), and that the variability among experiment station laboratories in analysis of dietary Ca, P, and Zn in mixed diets is quite large.

Effect of orally administered epidermal growth factor on the jejunal mucosa of weaned pigs.

The effect of ingested epidermal growth factor (EGF) on the small intestinal mucosa of conventionally weaned pigs was determined. At 21 days of age, 39 pigs were randomly distributed into suckling and weaned treatment groups that were administered 124 micrograms of EGF, 372 micrograms of EGF, or the dosing compound daily. Fecal water content was determined daily. On postweaning days 0, 3, 6, and 9, representative pigs from each group were euthanatized, and jejunal mucosa samples were collected for determination of villus-to-crypt ratio, total protein content, disaccharidase activities, and microbiological populations. At postweaning day 3, the 372-micrograms dose of EGF significantly (P less than or equal to 0.05) increased jejunal lactase and sucrase activities in the weaned pigs. Increased lactase activity was not greater than that of the suckling pig controls, whereas sucrase activity was significantly (P less than or equal to 0.05) higher than that of the suckling pig controls. Significant changes were not observed in villus-to-crypt ratio, mucosal protein content, or disaccharidase activities on other collection days.