BW Ratio Research Articles

Performance characteristics and economic comparison of broiler chickens fed wheat- and triticale-based diets

The effects of triticale and wheat on broiler (mixed sexes) performance and cost of production were compared. In experiment 1, wheat- and triticale-based diets were fed to 3 strains of broilers (Ross × Ross, Hubbard x Hubbard, and Ross × Hubbard). Each of the diets was provided to 5 cages/strain (n = 10 chicks/cage; 1,273 cm2/bird). Weekly BW, gain, feed consumption, and feed conversion ratio (FCR; g of feed/g of gain) were determined. At 42 d, 4 chicks/pen were shipped to a commercial processing plant. The plucked, eviscerated carcasses were evaluated for carcass traits. Overall, the triticale-fed birds had lower final BW and average daily gain and higher FCR. Eviscerated carcass, thigh, and drum weights were lower, but pectoralis minor as a percentage of carcass weight was greater in triticale-fed birds. In experiment 2, a wheat diet and a diet in which triticale was substituted (by weight) for wheat were provided in a 3-phase feeding program. Each diet was provided to 2 identically-equipped commercial barns housing 17,034 broilers each. Individual BW of a sample of birds were recorded in each barn at 0, 19, 34, and 42 d, corresponding to the beginning and end of each dietary phase. Feed consumption and FCR were calculated for each barn. An analysis of each of the diets was calculated using a broiler chicken production cost model. Final BW, feed consumption, carcass weight at processing, flock uniformity, percentage of Grade A carcasses, and percentage of condemned carcasses were not affected by cereal source. Overall FCR (2.165, 2.036; P = 0.0052), feed cost ($ 0.617, $ 0.577/kg live weight; P = 0.0260), and total cost of production ($ 1.019, $ 0.972/kg live weight; P = 0.0183) were greater for the triticale than wheat diets, respectively. Triticale would be an economically feasible replacement for wheat in broiler diets when its price is less than or equal to 95% of the cost of wheat, less $ 18 (Canadian). Increased knowledge of the available nutrient profile of triticale, as well as least-cost feed formulation would likely increase the value of triticale relative to wheat for broilers.

Replacing soybean meal with sunflower seed meal in the ration of Awassi ewes and lambs

Three experiments were conducted to evaluate sunflower seed meal (SFM) as a substitute for soybean meal (SBOM) in rations of fattening Awassi lambs and milking ewes. In the first experiment, 12 Awassi lambs were assigned into four groups to measure the digestibility of the SFM and experimental rations. The control group ration (1) contained SBOM while in the other two rations, SFM replaced SBOM at a level of 50% (2) and 100% (3), respectively. The fourth group was fed only SFM. No significant differences were observed between lambs fed the experimental rations in digestibilities of DM, OM, CP, CF, NDF, ADF or N balance. NFE had a higher ( P<0.05) digestibility for ration 1 than ration 2. In the second experiment, the voluntary feed intake was measured for the Awassi ewes during milking and dry period using 36 Awassi lactating ewes. For the two stages there were no significant differences between rations in voluntary intake. Milk yields (kg/herd per day), milk fat (%) and milk total solids (%) were not different among groups. In the third experiment, 42 lambs (males and females) were divided randomly into three treatment groups. Rations were the same experimental rations in the digestibility study. There were no significant differences in the average final BW, ADG and average feed conversion ratios (FCR) among the treatments. These experiments showed that SFM could replace SBOM as a protein source in rations of fattening Awassi lambs and milking Awassi ewes.

Alterations in adult rat heart after neonatal dexamethasone therapy.

Glucocorticoid treatment in preterm babies to prevent chronic lung disease causes myocardial hypertrophy and increased myocardial protein content. Although these changes are thought to be transient, there is evidence that dexamethasone (DEX) induces permanent myocardial abnormalities as well. We investigated whether a therapeutic course of neonatal DEX in rat pups produces anatomic and biochemical alterations in rat hearts during adult life. Twenty-four rat pups were treated with DEX on d 1, 2, and 3 (0.5, 0.3, and 0.1 micro g/g) of life, with doses proportional to those used in preterm babies. Twenty-four control pups were treated with saline. At d 7, wk 8, or wk 45 (n = 8 per group) rats were killed. The anatomic parameters measured were body weight (Bw, in grams), heart (myocardial) weight (Hw, in milligrams), and the Hw:Bw ratio. Myocardial total protein (Prot) and DNA content were determined, and the Prot:DNA ratio was calculated. Histopathology and morphometry were performed on 45-wk-old rat hearts. In DEX-treated rat pups, at d 7, Bw and Hw were lower and the Hw:Bw ratio was increased. DNA content was lower, Prot higher, and Prot:DNA ratio was increased. In 8-wk-old rats Bw, Hw, DNA content, Prot content or Prot:DNA ratio did not differ between groups, but the Prot:DNA ratio still tended to be higher in DEX-treated rats. In 45-wk-old rats Hw and Hw:Bw ratio were significantly lower and Prot:DNA ratio higher in DEX-treated rats. Histopathologic analysis showed larger cardiomyocyte volume, length, and width, indicating hypertrophy, and increased collagen, indicating early degeneration of individual myocytes. In conclusion, neonatal DEX treatment in rat pups causes a permanent decrease in heart weight, as well as hypertrophy and early degeneration of cardiomyocytes during adulthood.

Relationship between aging and nutritionally controlled growth rate on heat production of ewe lambs1

The hypothesis of this study is that ewes that have equal body weights, but differ in chronological age due to nutrient restriction, do not differ in metabolic rate. The objective of this study was to determine how reducing growth rate nutritionally alters the relationship between heat production per unit body weight and aging. Fasting heat production of 12 Dorset ewe lambs at 114 ± 2 d of age was determined, and ewes were assigned to treatments. Treatments consisted of two different feeding levels of the same diet (ME = 2.5 Mcal/kg DM and 16.6% CP). The High treatment was offered 4.5% of their weekly BW per day, and the Low treatment was offered 2.5% of their weekly BW per day. Each treatment consisted of six animals that remained within treatment for the remainder of the study. Indirect-calorimetry measurements were repeated every 6 wk. Treatments differed in both the linear and quadratic term for fasted BW on age (P < 0.001). The rate of BW gain decreased as ewes aged in the High treatment, and the rate of BW gain increased as ewes aged in the Low treatment. The heat production:BW (HP:BW) ratio decreased in the High treatment as ewes aged and was described well by a previously reported prediction equation, but the ratio in the Low treatment was not described by this same equation. Describing the HP:BW ratio on age response with treatment-specific decay functions fit the data better than the pooled treatment function (P < 0.001). The HP:BW ratio decreased rapidly in the Low treatment following feed restriction, but remained elevated compared to the High treatment as animals aged. After excluding the initial measurements in the Low treatment that were taken before nutritional treatments were imposed, the HP:BW ratio was best described by a linear decrease. In conclusion, this study suggests that a previous model taking into account proportion of mature body size is a reasonable predictor for heat production across breeds of sheep growing in nutritionally adequate environments; however, it cannot be extended to sheep that are proportionally smaller in their mature BW due to nutritional restriction.

Reviewing old concepts at the start of a new millenium: Growth restriction, adrenal hypoplasia, and thymomegaly in human anencephaly

Anencephaly has been associated frequently with intrauterine growth retardation (IUGR), consistently with adrenal hypoplasia, and occasionally with an enlarged thymus. Few studies have analyzed the relationship between gestational age (GA), IUGR, associated anomalies and thymomegaly in anencephaly. The aims of our study were to evaluate this relationship and to highlight the usefulness of anencephaly as a model when investigating immune-endocrine interactions. Fifty-two anencephalics' autopsies were reviewed retrospectively. Body weight, adrenal, and thymus weights were compared to prenatal, postnatal, and stillborn control values, and between associated and isolated anencephalic cases (presenting with and without other unrelated anomalies). Comparisons of adrenal and thymus weights were done by GA and by body weight. Thymus weight:body weight (TW:BW) ratios were compared to expected values. Anencephalics' body and adrenal weights were lower than their control values, whereas thymus weights did not differ. Body and thymus weights were twice as high in isolated than in associated anencephaly, whereas adrenal weights did not differ. Anencephalics TW:BW ratios were higher than their control values, higher in cases with IUGR, and higher in isolated rather than associated cases. When distributed by GA, thymus weights in anencephaly increased at a higher-than-expected rate. Our results suggest that adrenal hypoplasia is invariably present in anencephaly, and depending on an underdeveloped pituitary gland, seems to be independent of its etiology. On the contrary, IUGR mainly exists in associated cases and thymus enlargement mainly exists in isolated cases, suggesting a relationship with the underlying cause.

Effect of trihalomethanes on cell proliferation and DNA methylation in female B6C3F1 mouse liver.

Trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane, and bromoform) are regulated organic contaminants in chlorinated drinking water. In female B6C3F1 mouse liver, the 4 trihalomethanes have demonstrated carcinogenic activity when administered by oral gavage; however, chloroform was not carcinogenic when administered in drinking water. Female B6C3F1 mice were administered the trihalomethanes for 11 days by gavage at 2 dose levels or in the drinking water at approximately 75% saturation. When administered by gavage, the trihalomethanes were toxic to the liver, increased the liver:body weight (bw) ratio, and increased the proliferating cell nuclear antigen-labeling index (PCNA-LI). Chloroform and bromodichloromethane were the most toxic, and they increased the liver:bw ratio the most, while bromoform and chloroform increased the PCNA-LI the most. When administered in drinking water, the toxicity of the trihalomethanes was similar to their low gavage-dose. Furthermore, only chloroform significantly increased the liver:bw ratio and bromoform and chloroform increased the PCNA-LI. Chloroform and bromodichloromethane decreased the level of 5-methylcytosine in hepatic DNA. Methylation in the promoter region of the c-myc gene was reduced by the trihalomethanes. Chloroform administered by gavage was more efficacious than given in drinking water; the efficacy of the other trihalomethanes did not differ for the 2 routes. Thus, in mouse liver, the trihalomethanes administered by gavage enhanced cell proliferation and decreased the methylation of the c-myc gene, consistent with their carcinogenic activity. Furthermore, the more modest toxicity, enhancement of cell proliferation, and decreased methylation induced by chloroform administered in drinking water correlated with its lack of carcinogenic activity. Hence, the activity of the trihalomethanes was dependent on the rate of delivery, i.e. rapid by oral gavage and more slowly in drinking water.

Kidney Weight (Kw) and Body Weight (Bw) Ratios Predict Glomerular Filtration Rate (GFR) in Transplant Recipients

Kidney Weight (Kw) and Body Weight (Bw) Ratios Predict Glomerular Filtration Rate (GFR) in Transplant Recipients

Catecholamine metabolism inhibitors and receptor blockades only partially suppress cardiac hypertrophy of juvenile visceral steatosis mice with systemic carnitine deficiency

To clarify the mechanism of cardiac hypertrophy in carnitine-deficient JVS mice, we studied die possible role of catecholamine metabolism. Cardiac hypertrophy occurs 2 weeks after birth. The turnover of norepinephrine in the ventricles of JVS mice at 2 weeks was 3 times that of control, but it was not different from control at 5 days when the heart weight was not changed. To evaluate the accelerated norepinephrine turnover, we examined the effects of catecholamine metabolism inhibitors (α-methyltyrosine and 6-hydroxydopamine) and catecholamine receptor blockades (propranolol, prazosin and yohimbine) on the ratio of heart weight to body weight ( HW BW ) and on the augmented expression of atrial natriuretic peptide (ANP) and the down-regulated carnitine deficiency-associated gene expressed in ventricle (CDV-1). The HW BW ratio in JVS mice treated with catecholamine metabolism inhibitors and receptor blockades was significantly lower than in JVS mice without treatment, but still higher than in controls treated with each drug and in JVS mice treated with carnitine. The HW BW ratio of JVS mice with propranolol was not significantly different from that of JVS mice treated with catecholamine metabolism inhibitors and was significantly lower than that of JVS mice treated with prazosin and yohimbine. Northern blot analysis showed that the altered expression of ANP and CDV-1 was not corrected in the ventricles of JVS mice treated with any of the drugs except carnitine. These results suggest that the catecholamine metabolism accelerated in JVS mice ventricles at 2 weeks is not the major cause of cardiac hypertrophy, but probably promotes cardiac hypertrophy mainly through the β-adrenergic signaling pathway. The aberrant gene expression of ANP and CDV-1 found in JVS mice seems to be independent of catecholamine metabolism, and mediated primarily by the systemic carnitine deficiency.

Gender-specific growth and hepatic neoplasia in medaka ( Oryzias latipes)

Brief exposure of hatchling medaka ( Oryzias latipes), to diethylnitrosamine (DEN), resulted in hepatic tumor formation in female medaka at an incidence of 2–3-fold higher than that of their male cohorts. Spontaneous liver tumor incidence was reported in unexposed 3–5 year old medaka. Gender differences were seen; higher incidence was in the females. Aspects of gender-specific growth in hatchling, immature and sexually mature control medaka are reported and studies sought to determine whether growth enhanced tumorigenesis in females. From a pool of 2000 mixed-sex, 3 week old medaka hatchlings, 1350 were exposed to an aqueous bath of 250 ppm DEN for 48 h. Another 650 hatchlings served as controls. For each fish, body- and liver-weights were recorded (BW and LW, respectively) and LW to BW ratio (hepatosomatic index—HSI) was estimated. Next, livers and carcasses were processed for histopathology. BWs of control females were significantly greater than that of males at weeks 8, 20, 32 and 44 ( P<0.05). LWs and HSIs were significantly greater in females versus males at all ages ( P<0.05). In the DEN-treated medaka, female BWs were significantly more than their male counterparts at weeks 8, 16, 20 and 32 ( P<0.05). Female LWs were greater than male values at all weeks except 4 and 6 ( P<0.05). Female HSIs were significantly greater than male HSIs at all times ( P<0.05). A higher incidence of foci of cellular alteration (40%) distinguished females from males (10%) at week 4 and these values reached 100% incidence (females) and 90% (males) at week 12. Tumor latency periods for adenomas and carcinomas were significantly shorter in females than in males. At week 20, the incidence of tumors was significantly higher in females than in males ( P<0.05). Results indicate that gender-specific differences appear in BW, but especially LW and HSI as a function of larval development, ovarian maturation and age in control and DEN-treated medaka. Tumor incidence and time to endpoint (latency period) demonstrate that female growth is a promotional-stimulus, positively modulating DEN hepatocarcinogenesis.

Cardiac hypertrophy in diabetic spontaneously hypertensive rats: role of angiotensin II?

1. In the present study the role of angiotensin II (AngII) in the development of cardiac hypertrophy in diabetes combined with hypertension was investigated. 2. Diabetes was induced in 8-week-old male spontaneously hypertensive rats (SHR) by intravenous injection of streptozotocin (45 mg/kg bodyweight). Diabetic SHR were treated with the angiotensin-converting enzyme (ACE) inhibitor ramipril at a dose of 0.4 mg/kg per day. 3. Twelve weeks following the onset of diabetes, hearts were arrested in diastole and were perfusion-fixed. The right ventricle and left ventricle plus septum were weighted and the volume of the ventricular walls was determined using the Cavalieri principle. 4. Induction of diabetes in SHR led to a significant reduction in bodyweight compared with non-diabetic control SHR and this was not affected by ramipril treatment. The development of hypertension was not as great in diabetic SHR compared with controls, such that at 12 weeks following the onset of diabetes systolic blood pressure (SBP) averaged 191 +/- 3 and 230 +/- 4 mmHg in diabetic SHR and controls, respectively. Ramipril treatment significantly lowered SBP in diabetic SHR. 5. The left ventricle plus septum volume:bodyweight ratio (LV vol:BW) was significantly higher in diabetic SHR compared with controls (3.83 +/- 0.19 and 3.26 +/- 0.16 mm3/g, respectively). Ramipril treatment did not affect growth of the left ventricle in diabetic SHR with the LV vol:BW ratio averaging 3.95 +/- 0.14 mm3/g. Similar trends on growth were observed in the right ventricle. 6. In conclusion, the development of cardiac hypertrophy in diabetic SHR appears to occur by mechanisms independent of AngII and the elevation of blood pressure.

Can blood gas values predict pulmonary hypoplasia in antenatally diagnosed congenital diaphragmatic hernia?

The prognosis of antenatally diagnosed congenital diaphragmatic hernias (CDH) is clearly related to the degree of pulmonary hypoplasia (PH). After birth, controversies remain regarding the implementation of various therapies, especially the use of extracorporeal membrane oxygenation (ECMO). In the literature, the persistence of a Pa o 2 below 100 mm Hg and of Pa co 2 above 40 mm Hg despite optimal conventional therapy indicates poor prognosis. Therefore, since 1992, published and personal experiences led the authors to exlude CDH patients from ECMO when conventional therapy (including high-frequency oscillatory ventilation and nitric oxide) did not obtain Pa o 2 of above 80 mm Hg and Pa co 2 of below 60 mm Hg. The aim of this retrospective study is to determine whether blood gas results correlate with postmortem findings. Between July 1990 and July 1994, 32 cases of CDH were monitored antenatally and managed postnatally at the authors' institution. Six patients survived; 26 died, including one immediately at birth. Thirteen were treated by ECMO. Seventeen had a best Pa o 2 of above 80 mm Hg, including the six survivors. Fourteen did not reach this level, and none of them survived. Twenty-three infants underwent postmortem examination. PH was assessed using two criteria: (1) lung weight to body weight ratio ( LW BW ) and (2) radial alveolar count (RAC). Two patients did not have hypoplasia ( LW BW > 0.018 ). Twenty-one patients had PH; 12 of them had an LW BW ratio of less than .009; for 9, the LW BW ratio was between .009 and .018, and the RAC (<3.1) confirmed PH. All infants with a best Pa o 2 of less than 80 mm Hg had PH. Patients with a best Pa o 2 of greater than 80 mm Hg included two infants who died from complications without PH, eight infants with demonstrated PH, and the six survivors. In conclusion. (1) No infant with nonhypoplastic lungs has been deprived of ECMO by the authors' criteria. (2) Adequate values of blood gases may not eliminate PH. Therefore, this probably justifies starting ECMO when conventional therapy fails. (3) Conversely, permanent poor values of Pa o 2 allowed the prediction of PH in all cases. Such patients probably can be excluded from ECMO treatment.

Purine derivative excretion and ruminal microbial yield in Malaysian cattle and swamp buffalo

Allantoin concentration was measured in urine ( n = 115) of Malaysian indigenous Kedah Kelantan (KK) cattle ( Bos indicus) and swamp buffalo ( Bubalus bubalis). The rectilinear relationships between allantoin excretion ( Y, g N day −1) and digestible dry matter (DM) intake ( X, kg day −1) for KK cattle and swamp buffalo were Y cattle = 0.238 + 0.836 X ( R 2 = 0.76, P < 0.01) and Y buffalo = 0.181 + 0.466 X ( R 2 = 0.65, P < 0.01). These relationships adjusted for body weight (kg 0.75, BW) and intake: BW ratio had lower R 2 values. No significant difference was detected between the intercepts (minimal endogenous allantoin excretion) of the rectilinear relationships, but the slope (allantoin excretion rate per unit food intake) for KK cattle was greater ( P < 0.01) than for swamp buffalo. In a second study, total purine excretion of fed, fasting and refed KK cattle and swamp buffalo was measured. Hypoxanthine + xanthine excretion by KK cattle and swamp buffalo was less than 3% of the total purine excretion. The KK cattle excreted three times as much allantoin as swamp buffalo when fed at 1% of DM of their BW (1.74 g N day −1 vs. 0.60 g N day −1), but allantoin excretion at the end of 6 days of fasting was not significantly different between species. Uric acid excretion was generally higher ( P < 0.05) for swamp buffalo than for KK cattle during fasting, but species differences were not consistent during the fed and refeeding periods. Total purine excretion of fed KK cattle was higher ( P < 0.05) than of fed swamp buffalo. The difference in allantoin and total purine excretion rates between KK cattle and swamp buffalo given the same diet and level of feeding is apparently the result of physiological and/or ruminal microbial differences between the species.

Effects of Enzyme-Inoculant Systems on Preservationand Nutritive Value of Haycrop and Corn Silages

Third-crop mixed grass-legume forage and corn were ensiled in 70-tonne bunker silos to evaluate the effects of a commercial carbohydrase enzyme-inoculant mixture (220 ml/tonne) and an experimental enzyme-inoculant mixture (264 ml/tonne) on silage fermentation and composition, ruminal degradation, and milk production. Twelve Jersey and 24 Holstein early lactation cows were fed one of four TMR at 32.5:32.5:35.0 haycrop silage:corn silage:concentrate (DM basis) containing a combination of treated and untreated silages from d 2 to 100 of lactation. Bunker silages were incubated twice in situ in fistulated cows in each dietary treatment to determine rates of DM and NDF degradation. Treatment of haycrop silage significantly reduced silage pH and acetic acid concentration and increased titratable acidity, lactic acid concentration, lactate: acetate ratio, and DM and NDF disappearances after 24h of ruminal incubation. Treated haycrop silage increased DMI:BW ratio and daily production of milk, milk protein, and SNF of early lactation cows. Application of the experimental mixture to corn silage did not change silage fermentation or composition, except that the concentration of NH3 was reduced. Enzyme-treated corn silage did not improve DMI and slightly reduced daily milk production in early lactation cows.

Prediction of performance of progeny from test station boars.

Data were obtained from 1,954 Duroc and 2,252 Yorkshire purebred and crossbred progeny sired by 34 Duroc and 32 Yorkshire boars, respectively. Boars were purchased from the North Carolina Swine Evaluation Station during August 1983 to December 1988. Boars were selected to represent high and low indexes at the test station. Progeny were raised and tested under conditions similar to commercial pig production at the Tidewater Research Station. For each breed of boar (Duroc and Yorkshire), breed type (purebred and crossbred), and sex (castrates and gilts) of progeny, regression coefficients of progeny traits on each sire trait were computed. Progeny traits were ADG, days to 104.3 kg BW (DAYS), backfat thickness (BF), and feed conversion ratio (FC). Sire traits were ADG, DAYS, BF, FC, and INDEX. Effects of boar test group and progeny test group were included in the models. Averaged over breed type and sex, a 25-unit (1 SD) increase in sire INDEX resulted in 14.5 g more ADG, 3.2 fewer DAYS, .57 mm more BF, and .017 lower FC in Durocs and 5.6 g more ADG, .01 more DAYS, .81 mm less BF, and .083 lower FC in Yorkshires. The low magnitude and variable signs of some regression coefficients suggested that predictions of progeny performance from performance of individual sires at the North Carolina Swine Evaluation Station were not very reliable. Differences between regressions for purebreds and crossbreds implied small correlations between the two breed types. Differences between Durocs and Yorkshires indicated that genetic parameters might not be the same for the two breeds.

The effect of feed intake and body weight on purine derivative excretion and microbial protein supply in sheep.

Urinary excretion of purine derivatives (PD) was used to estimate the microbial N (MN) supply to sheep in three experiments designed to examine the effects of DMI and BW on the efficiency of microbial N supply (EMNS) to the host animal. In Exp. 1, four sheep of about 45 kg BW were given 328, 656, 984, and 1313 g of DM/d of a hay/concentrate diet in a Latin square design. Excretion of PD per kilogram of digestible organic matter intake (DOMI) increased with intake, and EMNS increased from 12.0 to 28.3 g of MN/kg of OM digested in the rumen (DOMR). In Exp. 2, 19 sheep ranging from 22 to 73 kg BW were all offered 820 g of DM/d of the same diet as that fed in Exp. 1. Although DM digestibility was relatively constant, PD excretion varied from 4.5 to 13.5 mmol/d and EMNS from 8 to 36 g of MN/kg of DOMR, both inversely related to animal BW. In Exp. 3, five sheep of 48 to 57 kg BW were given a different diet at 702, 966, or 1,237 g of DM/d. Purine derivative excretion per kilogram of DOMI increased with the DMI:BW ratio. Calculated EMNS ranged from 23 to 35 g of MN/kg of DOMR. Pooled data from all experiments showed EMNS to be related to the DMI:BW ratio. It is suggested that the DMI:BW ratio defines the ruminal digesta passage rate and hence outflow of microbial protein. The results imply that the EMNS for a given diet is not constant, but changes with intake.

Effect of in Utero Vesicostomy on Pulmonary Hypoplasia in the Fetal Lamb with Bladder Outlet Obstruction and Oligohydramnios: A Morphometric Analysis

A model of early gestation bladder outlet obstruction and oligohydramnios in the fetal lamb is characterized by small, immature lungs (pulmonary hypoplasia). The current study examines how in utero relief of urinary tract obstruction produced early in gestation modifies pulmonary hypoplasia.Bladder obstruction was created at 60 days gestation in fetal sheep (term = 140 days); 11 fetuses then underwent in utero decompression at 95 to 100 days; six were left obstructed. Five normal fetuses served as controls and two underwent sham obstruction and vesicostomy. All were delivered and sacrificed near term (135 days), the right lung was inflation-fixed and its volume determined. Relative volumes of alveoli, alveolar ducts, and tissue, alveolar surface area, and alveolar numerical density were estimated morphometrically. Kidneys were examined histologically.In all animals persistent bladder obstruction produced oligohydramnios. Bladder obstruction to term produced pulmonary hypoplasia with a mean right lung volume-to-body weight ratio (LV:BW) of 14.3cc./kg. (normal = 36.4, p < 0.001). Structural immaturity was evidenced by an airspace fraction of only 57% (normal = 68%, p < 0.05). Kidneys in these animals were not dysplastic; there was hydronephrosis or evidence of spontaneous urinary decompression. In eight of the 11 animals, decompression improved the LV:BW ratio to 28.4cc./kg. (vs. obstructed, p < 0.001; vs normal, p < 0.05) and normalized maturity. All had increased amniotic fluid at delivery; kidneys in 7/8 animals were normal, and the other had moderate hydronephrosis. One of the 11 animals had normal kidneys, oligohydramnios, immature lungs, but with normal volume. Oligohydramnios was present in the other two of 11 fetuses despite successful decompression and they had markedly dysmorphic kidneys and profoundly hypoplastic and immature lungs (LV:BW 5.1cc./kg.).Even after 35 days (25% gestation) of obstruction, in utero urinary tract decompression permits better lung growth and maturation than in persistently obstructed animals. The degree of renal damage from obstruction appears to be a critical determinant in the correction of pulmonary hypoplasia.

Xylazine-induced pulmonary edema in rats

Inhibitors of cytochrome P450, such as SK&F 525-A, prolong the duration of xylazine-ketamine anesthesia and cause pulmonary edema (PE) and death in rats. To determine the cause of PE, Sprague-Dawley rats were given a single dose of xylazine (21 mg/kg, im) alone or in combination with ketamine (45 mg/kg, im) and/or SK&F 525-A (50 mg/kg, ip) and percentage lung to body weight ( %LW BW ) ratios (as an indicator of PE) were compared. The results indicated that xylazine caused PE which was independent of ketamine and was enhanced by SK&F 525-A. Subsequently, it was determined that 42 mg/kg xylazine, im, is an optimal edemagenic dose. Xylazine (42 mg/kg, im) increased the %LW BW ratio as compared to control. Pleural effusion (PLE) of various amounts was observed in 75% of the animals. The pleural fluid to serum protein ratio for xylazine was similar to that obtained for α-naphthylthiourea (5 mg/kg, ip). Extensive serous PLE and alveolar edema with hemorrhage were found at necropsy in xylazine-treated rats. Pretreatment with yohimbine (4.2 mg/kg), prazosin (20 mg/kg), tolazoline (20 mg/kg), yohimbine (4.2 mg/kg) plus prazosin (20 mg/kg), atropine (20 mg/kg), dimethyl sulfoxide (DMSO) (7.8 g/kg), allopurinol (50 mg/kg), superoxide dismutase (20,000 U/kg), catalase (20,000 U/kg), BW755C (50 mg/kg), ibuprofen (50 mg/kg), cystathionine (100 mg/kg) plus taurine (100 mg/kg) did not affect the %LW BW ratio. PLE was increased by yohimbine, yohimbine plus prazosin, and allopurinol, reduced by DMSO, and not changed in other groups. The results indicate that xylazine caused increased-permeability PE characterized by rapid onset, cellular damage and protein-rich pleural fluid. PE may not be mediated by adverse cardiovascular effects of xylazine and oxygen radicals are possibly involved in its etiology.

Tall Fescue Endophyte: Effect on Congenital Development and Pup Growth in Mice

This study was designed to assess effects of a diet containing endophyte (Acremonium coenophialum)-infected tall fescue seed on litter growth and development in mice. Twenty pairs of mature CD-1 mice were allocated to dietary treatments containing 50% (wt/wt) rodent chow plus either 50% endophyte-infected tall fescue seed or seed that was not infected. At parturition, six pups of approximately equal BW and sex ratio were selected from each litter and fostered to each of the dams for suckling, resulting in four suckling groups. Pups born to dams fed the infected diet weighed less at birth and experienced developmental delays in BW gain and in eye opening (16.7 vs. 13.7 d) regardless of the foster dam's diet. Pups born of dams fed the diet that was not infected attained the greatest growth rates and weaning weights; those suckling dams fed the diet that was not infected demonstrated the largest gains. Pups born of and suckled by dams fed the infected diet demonstrated greatly reduced growth rates and weaning weights compared with the other groups. Results suggest that the congenital effect on pups born of dams fed an infected diet was significant in lowering the growth rate of the pups during suckling. The dam's ability to provide nourishment to the pups also was lowered when fed this diet. When these two factors were combined, the differences were greater than for either factor separately.

Effects of Dietary Aflatoxin in Aflatoxin-Resistant and Control Lines of Chickens

The resistance to a single oral dose (12 mg of aflatoxin per kg of BW) and 4 wk of dietary aflatoxin (2.5 mg per kg of feed) were investigated in chicks selected for five generations for resistance to acute aflatoxicosis (AR) and unselected control (C) chicks. The AR chicks were more resistant to a single oral dose of aflatoxin and had significantly decreased sodium pentobarbital sleeping time compared to C chicks. Four-weeks exposure to dietary aflatoxin did not result in any significant change in BW or feed conversion ratios of chicks from either the C or AR line. However, more sensitive indicators of aflatoxicosis including plasma total protein, albumin, cholesterol concentrations, and gamma glutamyl transferase activity were significantly altered in C chicks but not in AR chicks fed aflatoxin. Percentages of liver lipid and liver hyperplasia score were also significantly altered as a result of dietary aflatoxin treatment in C but not AR chicks. These data indicate that selection-associated differences exist between the C and AR lines of chickens that convey resistance to not only a single oral dose of aflatoxin but also to a more chronic dietary exposure to aflatoxin.

Clinicopathological studies on pulmonary hypoplasia in very low birth weight infants.

Seven VLBW infants with pulmonary hypoplasia (P.H.) were studied retrospectively and their necropsied lungs were analyzed morphologically and histometrically in an attempt to establish the clinical and pathological criteria of P.H. Clinically they had various features as follows; 1) causes with oligohydramnios due to amniotic fluid leakage, 2) bell-shaped chest and/or small lung radiographically, 3) severe respiratory distress immediately after birth, 4) frequent complications with air leaks, lethal within several hours after birth. Pathologically they showed a series of changes; 1) remarkably decreased LW: BW ratios, less than 0.015, 2) decreased number of alveoli per alveolar duct, less than 3 or 4 alveoli/duct compared with 6.5 of normal controls at 28 weeks' gestation, 3) immature duct system and increased interstitium which suggested delay in growth and structural maturation of the lungs. It is suggested that the tendency to develop pulmonary air leaks is not only due to high pressure ventilation but also to histological immaturity of the lungs.