Biomedical subjects

V L Christensen

Publications and source records attributed to V L Christensen.

At least 55 records · Page 3Linked to original sources

PubMed1994

Administration of propionate to day-old turkeys.

The effects of salts of propionic acid on newly hatched turkeys were examined. In Experiment 1, poults were injected with .25 mL of 1 M solutions of either sodium propionate or calcium propionate. After a 24-h holding period, the poults were killed and assayed for blood glucose, liver weight, and liver glycogen. Sodium propionate increased blood glucose concentration but did not alter liver weight or liver glycogen compared with controls. Calcium propionate had no effect on blood glucose but increased liver weight and liver glycogen compared with controls. There was no mortality in saline-injected controls or sodium propionate poults; 4 of 10 poults injected with calcium propionate died. In Experiment 2, poults were administered 0 or 4% sodium propionate in the feed or 0 or 2% sodium propionate in the drinking water in a 2 x 2 factorial arrangement. Propionate depressed feed intake and body weight by both routes of administration. Propionate in the feed, but not drinking water, depressed liver weight and liver glycogen. Plasma uric acid was increased by propionate in either the feed or the water but was not above control amounts when propionate was given in both the feed and water at the same time. Plasma propionic acid was increased by propionate in the water but not by propionate in the feed. We conclude that the use of propionate in injectibles, drinking water, or feed of newly hatched turkeys is contraindicated.

Animals↗

PubMed1994

Changes in functional qualities of turkey eggshells in strains selected for increased egg production or growth.

Much past research has been devoted to physical eggshell qualities, i.e., weight, deformation, or egg density, but little research has investigated the functional eggshell qualities when expressed in terms of eggshell conductance to gases. Conductance is a measure of the ease with which gases diffuse across the pores of the shell and is (by Fick's law) determined by the number and geometry of the individual pores. The objective of the present study was to determine changes that have occurred in functional eggshell characteristics (eggshell conductance) following selection for egg production or growth over nearly 30 generations. Major changes have occurred in the physical dimensions of eggs from selected lines of turkeys compared with their respective randombred controls. Egg weights increased 11% due to selection for growth and decreased 14% due to selection for egg production. Other measurements such as length and width increased allometrically with egg weights. Selection for egg production has decreased the physical dimensions (egg weight, volume, or surface area) of eggs, and selection for growth has increased the same measurements, but adjustments have not been made by selected hens to increase or decrease the functional characteristic (conductance) allometrically (conductance constants). An interaction was observed in eggshell conductance constants as the hens aged, suggesting that genetic selection may affect functional characteristics. This suggests that the energetics of embryonic development may be different in eggs from turkey hens of various ages. Energetics may result in poor hatchability and poult quality. It can be concluded that as the hens aged the conductance and conductance constants did not change allometrically with increasing egg weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Effects of L-alanine injection and post-hatch deprivation of feed and water on glycogen reserves in turkey poults.

1. Glycogen concentration (mg/g) in liver, epiphyseal bone (proximal femoral chondyle) and toe (first medial phalanges) declined during post-hatch holding of poults fir up to 72 hr without feed and water. 2. Muscle (gastrocnemius) glycogen concentration was unchanged by post-hatch holding. 3. Glycogen concentration (mg/g) in the whole body was unchanged while whole body glycogen (total mg) content was decreased by holding. 4. Injections of 1 ml of 1 M L-alanine did not enhance whole body glycogen stores.

Alanine↗

PubMed1993

Effect of maternal dietary triiodothyronine on embryonic physiology of turkeys.

The objective of the present experiment was to feed triiodothyronine (T3) to lines of turkey breeders selected for egg production and growth, and an unselected control line. The data were collected to determine a genetic basis for thyroid-mediated maternal effects on embryonic physiology and livability. At 30 wk of age, turkeys of the three lines were photostimulated and half of each line was fed a diet containing .5 ppm T3. Maternal dietary T3 increased egg weight, reduced yolk solids and eggshell conductance constants, and increased albumen solids and water in eggs in all lines compared with control eggs. Hatchability in all lines was not affected by the dietary treatment (Control = 72.2%; T3 treatment = 70.7%), but there was a significant interaction between dietary T3 and line of turkey for the time of embryonic mortality, time of hatching, and carbohydrate metabolism of the embryo. The T3 increased mortality of the Egg line and unselected line during pipping, increased mortality of the Growth line in the plateau stage, but decreased its mortality during internal pipping. Reduced glycogen in liver as well as a reduced gluconeogenesis were evident in embryos of the two selected lines fed T3. It is concluded that genetic lines may have different metabolic patterns based on their genetic constitution in order to compensate for variations in egg solids and eggshell conductance constants. The metabolic patterns are reflected in different levels of embryonic blood plasma glucose, glycogen, and gluconeogenesis.

Animals↗

PubMed1992

Effects of injections of L-alanine, L-glucose and L-ascorbic acid in newly-hatched turkey poults on glucose metabolism.

1. Effects of subcutaneous injections of either L-glucose, L-alanine or L-ascorbate into newly-hatched, fasted turkey poults were examined. 2. There were no effects of injections on blood glucose concentrations at 20 hr post-injection. 3. Glucose injections inhibited hepatic glucose-6-phosphatase activity while alanine injections did not. 4. Both glucose and alanine injections enhanced hepatic glycogen reserves at 20 hr post-injection.

Alanine↗

PubMed1992

Posthatch carbohydrate feeding and subsequent performance of turkey poults.

In two floor pen trials, day-old poults were fed a low-protein (18.6%) diet for the first 24 or 48 h compared with control poults fed a 28% protein diet. Beyond these initial treatments, all poults were treated identically and were fed the normal progression of starter, grower, and finisher diets to market weight. The treatments did not alter market age body weight or feed conversion. Early mortality and feed intake during the first 48 h were unaffected by the treatments. Feeding the low-protein diet for 24 h enhanced liver glycogen reserves compared with the control. In a battery cage trial, diets containing 50, 33, or 15% available carbohydrate (20, 28, or 35% crude protein, respectively) were fed for 24 h posthatch. The diets had no effect on blood glucose level, but liver glycogen concentration increased with increasing dietary carbohydrate. The results clearly indicate that carbohydrate metabolism is altered by posthatch dietary carbohydrate level. The results also suggest that the dietary protein requirement during the first 24 or 48 h posthatch may not be as high as it is currently thought to be.

Animal Feed↗

PubMed1992

Effect of oxygen and maternal dietary iodine on embryonic carbohydrate metabolism and hatchability of turkey eggs.

Fertile turkey eggs were produced by hens fed supplemental iodine to decrease eggshell conductance. The eggs were then incubated in an oxygen-enriched environment during Days 25 and 26 of incubation to test the hypothesis that maternal dietary iodine has separate effects on the eggshell permeability and the developing embryo. Oxygen supplementation improved hatchability regardless of dietary iodine treatment, suggesting that oxygen availability may limit hatching of eggs with normal gas conductance. Oxygen and dietary iodine did not affect body weight but interacted prior to pipping to affect embryonic liver and heart glycogen. Dietary iodine increased liver glycogen at internal pipping. The effects of oxygen on embryos, which were correlated directly with hatchability, were increased liver growth prior to pipping and increased heart weight at external pipping and posthatching. It was concluded that supplementing oxygen to incubating turkey eggs may improve hatchability by increasing liver and heart growth. Dietary iodine played only a minor or modulating role in assisting embryos to survive.

Animal Feed↗

PubMed1991

Effects of stressors on blood glucose and hepatic glycogen concentrations in turkey poults.

1. The putatively stressful procedures of sexing, toe trimming, snood removal, beak trimming and injection of antibiotic solution, as performed in a commercial hatchery, elevated blood glucose levels and depressed hepatic glycogen levels in newly-hatched turkey poults. 2. The first procedure performed, cloacal sexing, was sufficient to elevate blood glucose, but all procedures were required before depression of hepatic glycogen occurred. 3. Blood glucose levels declined in both untreated (INITIAL) and fully-treated (FINAL) poults over a 24 hr holding period. 4. Hepatic glycogen declined with 24 hr holding of INITIAL poults but increased with holding of FINAL poults.

Animal Husbandry↗

PubMed1991

Dietary carbohydrate level and glucose metabolism in turkey poults.

1. Feeding British United turkeys (BUT) and Nicholas turkeys (NT) diets with varying carbohydrate levels for 24 hr post-hatch resulted in lower hepatic glucose-6-phosphatase activity and higher plasma glucose levels as dietary carbohydrate level was increased. 2. There were no differences between the strains in liver weight or glucose-6-phosphatase activity, but BUT exhibited higher plasma glucose values than did NT at the two highest levels of carbohydrate. Plasma glucose did not differ between strains at the lowest level of carbohydrate or in fasted poults. 3. Blood glucose values were consistently higher in both strains when sampled 1 hr after initial sampling of fasted poults. 4. Both strains were able to maintain the 1 hr blood glucose levels through 24 hr when kept at approximately 37 degrees C. 5. When held at approximately 21 C for the first hour and at approximately 37 degrees C through 24 hr fasted NT were able to maintain the initial blood glucose rise while BUT were not.

Animal Feed↗

PubMed1991

Increasing hatchability of turkey eggs by injecting eggs with pyridoxine.

1. In field trials, eggs from two flocks of Large White turkey hens were injected with about 0.2 ml saline solution containing 600 micrograms of pyridoxine hydrochloride in order to examine its effect on hatchability. 2. Also, in an aseptic laboratory trial, eggs from Large White turkey hens were injected with 0.2 ml of saline solution and 0.2 ml of saline solution containing 600 micrograms of pyridoxine hydrochloride. 3. In field trials, hatchability of pyridoxine-injected eggs was 4.6% higher (P less than 0.05) than the control (non-injected) eggs. 4. In the aseptic laboratory trial, hatchability of pyridoxine-injected eggs was 4.2% higher (P less than 0.05) than saline-injected and control (non-injected) eggs.

Animals↗

PubMed1991

Hatchability, hematological indices, and growth of turkey embryos incubated at high altitude with supplemented oxygen during the first and fourth weeks of incubation.

Turkey eggs were incubated at high altitude (1,700 m). Hatchability, hematology, and growth data were analyzed for the following treatments: 1) eggs receiving supplemented oxygen (SO) during the 1st wk of incubation (control eggs received no SO during the 1st wk); 2) eggs receiving SO during the 4th wk (control eggs received no SO during the 4th wk); and 3) the interaction effect of oxygen the 1st or 4th wk with SO the 1st and 4th wk or with no SO. Data analysis was carried out using orthogonal contrasts. Exposing incubating turkey embryos to oxygen the 1st wk or the 4th wk of incubation improved hatchability significantly (P less than or equal to .05) compared with the remaining treatments. When SO was given during the 4th wk of incubation, hemoglobin concentration in embryos decreased (p less than or equal to .05) during pipping compared with that of embryos without SO the 4th wk. Hemoglobin was increased (P less than or equal to .05) by increasing red blood cell numbers if SO was not given during Week 4, otherwise, the embryos increased (P less than or equal to .05) in mean cellular hemoglobin to increase hemoglobin. When oxygen was supplemented the 1st wk of incubation, reticulocyte maturation was slowed (P less than or equal to .05) compared with no SO the 1st wk. Oxygen exposure during the 1st wk or 4th wk of incubation reduced (P less than or equal to .05) body weights of embryos during pipping and at hatching compared with those of embryos in the remaining treatments. Oxygen supplementation during Week 4 affected (P less than or equal to .05) heart growth at the prenatal, internal pipping, and postnatal stages of respiration.(ABSTRACT TRUNCATED AT 250 WORDS)

Altitude↗

PubMed1991

Influence of diet-mediated maternal thyroid alterations on hatchability and metabolism of turkey embryos.

Large White turkey breeder hens from a strain exhibiting poor hatchability were fed thyroid-altering diets. The following dietary treatments were fed to randomized groups of hens for 15 wk of egg laying: 1) 16.5% protein turkey breeder diet (control), 2) the control diet containing 2.1 ppm supplemental iodine, 3) the control diet containing .1% thiouracil, and 4) the control diet containing .5 ppm triiodothyronine (T3). Blood samples were taken from hatching embryos from hens fed each diet. Embryonic hearts and livers were weighted prior to and during pipping as well as after hatching. Blood plasma was analyzed for thyroxine (T4), T3, and glucose. Livers were assayed for glucose-6-phosphatase activity. Supplemental maternal dietary iodine elevated embryonic T4 concentrations prior to pipping. Dietary T3 and iodine increased hepatic glucose-6-phosphatase activity and blood plasma glucose concentration prior to pipping. Feeding thiouracil increased embryonic liver weights but decreased heart and body weights. Blood plasma T4 was elevated in embryos from hens fed thiouracil but blood glucose levels were depressed because of a lack of increased glucose-6-phosphatase activity. Feeding iodine decreased the enzyme activity at internal pipping. It is suggested from the data that maternal thyroid metabolism may influence hatchability via embryonic thyroid and carbohydrate metabolism during hatching.

Animals↗

PubMed1991

Iodine toxicity in large white turkey breeder hens.

Iodine was fed to turkey breeder hens during a 20-wk laying cycle to determine the appropriate dietary level to support reproduction and avoid toxicity. A basal diet that contained by analysis. 7 ppm iodine supported good hatchability of Large White turkey eggs. Supplementing 35 or 350 ppm iodine to the basal diet resulted in toxic effects (P less than or equal to .05) on hatchability. Feeding 350 ppm also depressed (P less than or equal to .05) egg weights, egg production, and eggshell water vapor conductance. Embryonic mortality data indicated that toxic effects of iodine on embryos occur principally during the 1st wk of incubation and immediately prior to and during pipping. It was concluded that iodine toxicity may occur in Large White turkey breeder hens when 350 ppm are fed in the diet.

Animals↗

PubMed1991

The effect of dietary iodine on the hatchability of eggs from two commercial strains of turkeys.

Supplemental dietary iodine (3.5 mg/kg) was fed to two commercial strains [British United Turkeys (B) and Nicholas (N)] of turkey breeder hens. The basal diet contained .7 mg/kg of iodine. Observations were made on hen body weights, feed consumption, hatchability, egg weights, and egg functional characteristics to test the hypothesis that there are differences between commercial strains of turkey breeder hens in the dietary iodine requirement for reproductive success. Supplemental iodine decreased (P less than or equal to .05) functional egg characteristics of both strains. Egg production and hatchability were influenced by an interaction between strains and dietary iodine (P less than or equal to .05). In Strain B hens, egg production and hatchability declined (P less than or equal to .05) when hens were fed supplemental iodine but in Strain N hens no effects on hatchability were observed and egg production increased (P less than .05) with iodine supplementation. The decline in hatchability of eggs from Strain B hens was due to significant (P less than or equal to .05) increases in embryonic mortality during the 1st wk of incubation and during pipping. The treatments resulting in depressed hatchability caused embryos to rely more (P less than or equal to .05) on glycogenolysis than gluconeogenesis during pipping and hatching. The Strain B embryos utilized gluconeogenesis more during pipping (P less than or equal to .05) than Strain N embryos and embryos from Strain B iodine-fed hens had a lower rate of gluconeogenesis than those from hens not fed iodine. It is concluded that there are differences among strains of turkey breeder hens in their dietary iodine requirement for optimal hatchability.

Animal Feed↗

PubMed1990

Influence of diet-mediated maternal thyroid alterations on functional properties of turkey eggs.

Maternal thyroid status was altered by means of diet to determine its effect on functional properties of turkey eggshells. Hens were fed a control diet (CON), the CON diet containing .5 ppm triiodothyronine (T3), the CON diet containing 2.1 ppm iodine as potassium iodide (KI) or the CON diet containing .1% thiouracil (THIO). Feeding T3 decreased plasma thyroxine but elevated plasma T3 concentrations compared to CON. The KI diet had no effect on plasma thyroid hormone concentrations, but feeding THIO depressed plasma thyroxine with no effect on T3, resulting in an elevated ratio of the two hormones compared to the CON ratio. Feeding KI decreased egg volume and T3 increased egg density compared to CON, but no effects on egg weight, surface area, width, or length were noted. Dietary T3 depressed eggshell water vapor conductance compared to CON. Dietary iodine resulted in thinner eggshells with fewer pores than the CON, whereas THIO caused significantly more pores in eggshells than CON but had no effects on shell thickness. Dietary KI had no effects on maternal plasma thyroid hormone concentrations, suggesting that the effects were due to iodine availability rather than to thyroid hormones. It is concluded that the availability of iodine to turkey breeder hens may influence eggshell characteristics.

Animals↗

PubMed1990

Hematological indices of turkey embryos incubated at high altitude as affected by oxygen and shell permeability.

Turkey eggs (Meleagris gallopavo) were incubated at an altitude of 1,707 m to test the effects of oxygen supplementation and increased eggshell permeability by removal of shell cuticle on embryonic hematology. Turkey embryo hematological indices measured were red blood cell count (RBC), hemoglobin concentration, packed cell volume, mean cellular volume, mean cellular hemoglobin, and percentage of reticulocytes. Although hemoglobin concentration measured during pipping increased as expected by increasing RBC, no significant differences were observed between oxygenation, or permeability treatments, or their interaction. Under the high altitude conditions of the present experiment, increased hemoglobin concentrations in all treatments corresponded to increased numbers of erythrocytes with constant mean cellular hemoglobin. None of the remaining hematological indices examined was affected by oxygen or permeability treatments. It was concluded that turkey embryos incubating at 1,707-m elevation make no additional changes in hemoglobin concentrations during the plateau stage in oxygen consumption (25, 26, and 27 days of incubation) when exposed to increased oxygen tension (151 mm Hg versus 135 mm Hg) or increased eggshell permeability (19.9 mg H2O/day per mm Hg versus 23.2 mg H2O/day per mm Hg).

Altitude↗

PubMed1989

Comparisons of turkey embryos incubated in tenuous or dense gas environments--II. Organ growth.

1. Eggs from large white turkeys were incubated in tenuous and dense gas atmospheres. 2. Tenuous gases resulted in heavier embryos until the onset of the plateau stage in oxygen consumption when dense gas environments caused heavier embryos. 3. Tenuous gases decreased heart and lung weight but increased liver weight. 4. Oxygen supplementation in tenuous gases increased liver weights but had no effect on lung or heart weights. 5. The data suggest an interaction of gas density and partial pressures of individual gases which affects breathing and the physiology of developing poult embryos.

Animals↗

PubMed1989

Blood plasma catecholamine concentration of poult embryos during the transition from diffusive to convective respiration.

1. Plasma catecholamines were determined in turkey embryos. 2. Decreased eggshell permeability depressed dopamine and epinephrine, but increased permeability also depressed epinephrine. 3. Norepinephrine (NE) was greatest before transition to convective respiration when hypoxia occurs. 4. NE was associated inversely with eggshell permeability. 5. Catecholamines appear to assist the embryo during hatching hypoxia.

Animals↗