Effects of feeding a liquid diet for one year to New Zealand White rabbits

We compared the long-term effects of a newly designed liquid diet with a commercially available dry diet in New Zealand White rabbits. Body weight gain, feed consumption, and plasma lipid concentrations were measured periodically throughout the 1-year study. In addition, specific hepatic enzyme activities in serum were quantified to examine the effects of liquid diet on the liver over the 1-year feeding trial. At 52 weeks, body weight gains between the liquid- and dry-fed groups were similar. Regardless of sex, plasma phospholipid concentrations were higher in the control group than in the liquid-fed group. Plasma triglyceride concentrations were increased in liquid-fed female rabbits, compared with either male group or control-fed females. A somewhat similar effect was observed in plasma cholesterol concentration, which was higher in female rabbits regardless of diet type. After the 52-week trial, the rabbits had no clinical biochemical signs of liver damage. Results of this study indicate that a liquid diet can be fed to New Zealand White rabbits for a long period, and may provide an alternative route (food source) for future pathophysiologic studies.

Diabetes mellitus in a new kindred with familial hypobetalipoproteinemia and an apolipoprotein B truncation (apoB-55)

Familial hypobetalipoproteinemia is an autosomal co-dominant disorder, which in a minority of cases is due to a truncation producing mutation in the apoB gene. We have identified an apoB mutation in a 40-year old hypobetalipoproteinemic man with Type II diabetes mellitus. Immunoblotting of plasma revealed a major band for apoB-100 and a minor band with estimated size between apoB-52 and apoB-55. The proband's 75-year old father with Type II diabetes and a non-diabetic daughter also possessed the truncated protein. Direct sequencing of the amplified fragment of genomic DNA revealed a C-->T transition at nt 7692 in exon 26 of the apoB gene. This substitution yielded a premature stop codon at residue 2495 and abolished a BsaI restriction endonuclease site. The identical mutation has been described previously; however, the genotypes and ancestors of the kindred were different, suggesting that the mutation may have occurred independently. The majority of apoB-55 was eluted as particles smaller than LDL-sized apoB-100, and floated mostly between the LDL and HDL density range. It is worth noting that despite the presence of Type II diabetes, both the proband and his father have very low plasma lipid levels and neither have any clinically manifest macrovascular complications.

An evaluation of the lipoprotein composition and corresponding apolipoproteins in the newly hatched male and female broiler chick from two different age flocks

The purpose of this experiment was to investigate the effects of breeder flock age (30 vs. 39 weeks) and sex of the newly hatched chicks on lipoprotein composition and apolipoprotein AI (apoAI) and B (apoB) concentrations. Additionally, fast protein liquid chromatography (FPLC) was used to evaluate which lipoprotein fraction (VLDL vs. LDL vs. HDL) carried the bulk of cholesterol in newly hatched chicks. Other lipoproteins were separated by density gradient ultracentrifugation to determine their chemical composition. Serum apoAI and apoB were compared by density scanning of VLDL, IDL, LDL and HDL fractions from sequential ultracentrifugation spins. The lipoprotein profile and apolipoprotein concentrations were similar for all chicks, so samples were pooled across both sexes and age groups to strengthen the data. For the lipoproteins, VLDL had the highest level of triglycerides followed by IDL, whereas the LDL particles had the highest levels of cholesterol esters compared to all other fractions. After separating the lipoprotein particles by size (FPLC) it was determined that both LDL and HDL carried approximately equal levels of cholesterol. These data suggest that lipoproteins in newly hatched chicks are not effected by sex or flock age chosen. In addition, LDL and HDL cholesterol are carried equally in newly hatched chicks.

Broiler breeder age and dietary fat influence the yolk fatty acid profiles of fresh eggs and newly hatched chicks

The purpose of the present study was to investigate the combined effects of breeder age (36-, 51-, or 64-wk) and different dietary fat sources (3% added corn oil, poultry fat, or lard) on lipids in fresh egg yolks and yolks of newly hatched chicks. Isocaloric breeder diets were altered by the inclusion of different types of dietary fat such that the poultry fat and lard diets had the highest levels of saturated fatty acids when compared to the corn oil diet. Fresh egg yolks obtained from 36-wk-old breeders exhibited higher levels of palmitoleic acid when compared to the levels observed in fresh egg yolks of 51- or 64-wk-old breeders. Furthermore, these levels decreased significantly by 21 d of incubation only in eggs from 36-wk-old hens. At 36 wk of breeder age, the levels of oleic and arachidonic acid were higher in yolks from hatched chicks than in previous fresh egg values, regardless of type of added dietary fat; whereas the level of linoleic acid was higher only in yolks from hatched chicks compared to those of fresh eggs from 36-wk-old hens fed 3% added corn oil. These data suggest that breeder age influences the utilization of yolk lipid by developing embryos, and that the type of fat provided in the diet may have an additional influence.

Effects of added lard fed to broiler chickens during the starter phase. 1. Body and selected organ weights, feed conversion, hematology, and serum glucose

The effects of added lard in starter diets on BW, selected organ weights, feed conversion, hematological indices, and serum glucose were determined weekly in broiler chickens between 14 and 42 d of age. Nonisocaloric starter diets were formulated to contain either 0, 3, or 7% added lard, where the megacaloric percentages of all major nutrients were held constant. Broiler chickens received either 0, 3, or 7% added lard in starter diets through 10 d of age (S1), followed by either 3 or 7% added dietary lard through 21 d of age (S2). All possible combinations of the three S1 diets and two S2 diets yielded six total dietary treatments. A common grower diet was provided after 21 d. Body weight was not affected by diet and feed conversion did not increase between 21 and 42 d when birds were fed 3 or 7% added lard in the S1 diet. The effects of the S1 and S2 diets on relative liver weight were inconsistent over time and were not influenced by sex. Hematocrits were increased across time in birds fed 3% S1 diets and plasma protein concentrations were increased at 14 d in birds fed 7% S1 diets. It was concluded that the response of broiler chickens between 14 and 42 d to different levels of dietary lard was influenced by age of feeding during the starter period.

Effects of added lard fed to broiler chickens during the starter phase. 2. Serum lipids

The effects of lard added to starter diets on various serum lipids were determined in broiler chickens between 14 and 42 d of age. Nonisocaloric starter diets were formulated to contain either 0, 3, or 7% added lard, where the megacaloric percentages of all major nutrients were held constant. Birds received either 0, 3, or 7% added lard in starter diets through 10 d of age (S1), followed by either 3 or 7% added dietary lard through 21 d of age (S2). All possible combinations of the three S1 diets and two S2 diets yielded six total dietary treatments. A common grower diet was provided after 21 d. Concentrations of various serum lipids were determined weekly from 14 to 42 d of age. The effects of both the S1 and S2 diets on total cholesterol, low density lipoprotein cholesterol (LDLC), and high density lipoprotein cholesterol (HDLC) were inconsistent and were influenced by sex between 14 and 42 d of age. However, serum triglycerides and very low density lipoprotein cholesterol concentrations showed progressive increases over the 14 to 42 d period in birds that received dietary lard at either level in the S1 diet. These same serum constituents also increased to the greatest extents over the same period when birds were provided 3% added lard in the S2 diet. It was concluded that the response of broiler chickens between 14 and 42 d to different levels of dietary lard were influenced by age of feeding during the starter period. Furthermore, the specific effects of the diets on serum cholesterol, LDLC, and HDLC concentrations between 14 and 42 d varied with the sex and age of the bird.

Normal intestinal dietary fat and cholesterol absorption, intestinal apolipoprotein B (ApoB) mRNA levels, and ApoB-48 synthesis in a hypobetalipoproteinemic kindred without any ApoB truncation

The purpose of this study was to characterize intestinal apolipoprotein B (apoB) metabolism in subjects with familial hypobetalipoproteinemia (FHBL), where segregation analysis supports linkage to the apoB gene but no apoB truncations are present. We investigated cholesterol and fat absorption, intestinal apoB mRNA synthesis and editing, as well as apoB-48 synthesis. Plasma triglycerides (TG) and retinyl palmitate in the chylomicron fractions were analyzed after 12 hours of fasting and then repeatedly for 14 hours after ingestion of a vitamin A-containing high-fat meal. Cholesterol absorption was assessed using a dual stable-isotope method. Mean peak times and concentrations and areas under the curve (AUCs) for fat absorption and mean percentages of cholesterol absorption were comparable in affected and nonaffected family members. Intestinal biopsies were extracted for total RNA and also incubated with 35S-methionine for measurements of apoB synthesis. Similar quantities of apoB mRNA were found to be expressed in the intestine in affected and control subjects by RNase protection assay. ApoB mRNA editing assay showed that the majority of apoB-100 mRNA was edited to the apoB-48 form to a similar extent in both groups. Virtually no apoB-100 protein was synthesized by the intestine in any subject, and apoB-48 protein synthesis was not significantly different in the affected individuals. These data are consistent with in vivo metabolism data that show normal production rates for liver-derived apoB-100 but increased apoB-100 fractional catabolic rates in affected members of this family. Thus, the molecular defect probably does not affect transcription, translation, or secretion of apoB-containing lipoproteins, but may instead affect their clearance.

Alcohol increases plasma levels of cholesterol diet-induced atherogenic lipoproteins and aortic atherosclerosis in rabbits

The purpose of the present study was to reexamine the relationship between alcohol and atherosclerosis. Two experiments were performed: The first contained three groups of New Zealand White (NZW) female rabbits. The control group was fed a cholesterol-containing liquid diet and the other two groups were fed the same diet with either 20% or 30% of the calories supplied by alcohol. The second experiment had two treatments: one control group and another group fed a 10% alcohol diet. In experiment 1, alcohol at the 20% and 30% levels increased VLDL and LDL but not HDL compared with levels in control rabbits. Hepatic mRNA levels of apolipoprotein (apo) A-I, apoB, and 7 alpha-hydroxylase were not affected by alcohol. However, the LDL-receptor mRNA was decreased to half of control values by either 20% or 30% alcohol. Lesion areas and aortic cholesterols were significantly increased in the 20% and 30% alcohol-treated groups. Also, significant correlations were found between plasma cholesterol levels and total lesion area or lesion cholesterol contents. In experiment 2, the 10% alcohol-treated rabbits showed no differences in circulating lipoproteins, LDL-receptor mRNA, or lesion formation above that observed in controls. These experiments suggest that alcohol substituted at 20% or 30% of the dietary calories induces hypercholesterolemia and more aortic atherosclerotic lesions. The alcohol-induced accumulation of VLDL and LDL was accompanied by low hepatic LDL-receptor mRNA levels, suggesting that alcohol may affect LDL-receptor expression and rates of lipoprotein clearance, but more experiments are needed to evaluate this possibility.

Influence of yolk on blood metabolites in perinatal and neonatal chickens

Two experiments were conducted to assess the role of the yolk sac during the perinatal period (i.e., from embryonic Day 18 through hatch) and until 15 days after hatching. Experiment 1 describes changes in several yolk components. Approximately 70% of the yolk was absorbed during the perinatal period. Moisture, lipid, protein, and carbohydrate fractions were all utilized during this period. In Experiment 2, the age at which set-point physiological levels of several blood metabolites, as well as the magnitudes of these levels, in deutectomized (DT) chicks (surgical ablation of the yolk sac within 1 hr post-hatch) were not different from non-DT controls. Results indicate that the yolk sac plays a central role in the hatching process of chicks, rather than serving as a major metabolic reserve during the neonatal period.

Metabolism of apolipoprotein B-100 in a kindred with familial hypobetalipoproteinemia without a truncated form of apoB

Familial hypobetalipoproteinemia (FHBL) exists in three forms: a) FHBL genetically linked to truncated forms of apolipoprotein B (apoB); b) FHBL linked to the apoB gene but with no apoB truncations; and c) FHBL not linked to the apoB gene. Mean production rate (PR) of apoB-100 in FHBL subjects heterozygous for apoB truncations is approximately 30% of normal. In a 49-member D-kindred (FHBL phenotype defined as apoB < 40 mg/dl), no apoB truncations were detectable either by immunoblotting of plasma or by sequencing of relevant stretches of the apoB gene. Herein we report on the kinetic parameters of apoB-100-containing lipoproteins in four affected members of the D-kindred, and compare their kinetic values to 14 normal subjects, and 8 previously reported FHBL subjects heterozygous for various truncated forms of apoB. After an 8-h primed intravenous infusion of [13C]-leucine, enrichments of apoB-100 were assessed by gas chromatography-mass spectrometry and kinetic parameters were calculated by multicompartmental modeling. The affected members of the D-kindred had similar very low, intermediate, and low density lipoprotein (VLDL, IDL, and LDL) PRs as normal controls, but their fractional catabolic rates (FCR) for VLDL and LDL were approximately 2 and 3 times higher, respectively, than those of normals. By contrast in apoB truncation subjects, apoB-100 PRs were uniformly reduced, while apoB-100 FCRs were similar to normals. Thus, diverse physiologic mechanisms are responsible for the low apoB levels in these two different, genetically determined forms of FHBL.

Naloxone attenuates serum corticosterone and augments serum glucose concentrations in broilers stimulated with adrenocorticotropin

The effects of exogenous naloxone and adrenocorticotropin (ACTH) on circulating concentrations of corticosterone and glucose in broilers were determined. Birds were injected i.m. at 0 and 2 h with either saline or naloxone, then i.v. at 2.5 h with either saline or ACTH. Control birds received saline at each injection. Blood samples were taken before the experiment started (0 min) and 30, 60, and 90 min after the last injection. Intramuscular injections of naloxone significantly reduced subsequent ACTH-stimulated increases in serum corticosterone; however, when followed by saline, naloxone elevated corticosterone by 90 min after the final injection of saline. Glucose levels were significantly elevated at 60 min in birds receiving ACTH i.v., but remained elevated through 90 min in birds pretreated with naloxone. Naloxone pretreatment attenuated serum corticosterone but augmented serum glucose concentrations in ACTH-stimulated broilers.

Effects of consecutive thiouracil exposures in the juvenile and adult single comb White Leghorn chicken on body weight and reproductive performance

The effects of consecutive exposures to dietary thiouracil (TU) in juvenile and adult Single Comb White Leghorn chickens on plasma thyroxine (T4) concentrations, egg production (EP), egg weight (EW), concentrations eggshell quality were determined. Thiouracil was provided in the feed at levels of 0, 0.1, or 0.2% (PTRT) from 0 to 6 wk of age and at levels of 0 or 0.1% (TRT) from 32 to 38 wk of age. Body weight gain was simulated but T4, EW, EP, and eggshell quality were generally reduced by 0.1% TU TRT. However, TU PTRT alleviated a latent depressing effect of TU TRT on BW after 38 wk of age. Thiouracil PTRT, particularly at the 0.2% level, induced significant decreases in EW but increased EP between 32 and 50 wk. The effects of early thyroid suppression in juveniles with TU PTRT on the subsequent reproduction of adults were primarily in response to a delay in the onset of sexual maturity, and not directly to prolonged responses in T4 or BW that extended into lay.

Effects of added dietary lard on body weight and serum glucose and low density lipoprotein cholesterol in randombred broiler chickens

The effects of dietary lard on serum glucose (GLU) and lipids were determined in Athens-Canadian randombred broiler chickens. Birds were provided either 0, 3, or 7% added lard in nonisocaloric starter diets through 10 d of age (S1), followed by either 3 or 7% added dietary lard through 21 d of age (S2). A common grower diet was fed to all birds after 21 d. Body and organ weights, feed conversion, and concentrations of various blood constituents, including serum GLU and lipids, were determined weekly from 14 to 42 d of age. Constant levels of added fat in both S1 and S2 diets generally led to higher BW in males at 42 d. Relative testes weight at 14 d was higher in males fed 3% than in those fed 7% S2 diets, whereas 7% added lard in S2 diets preceded by no added fat in S1 diets resulted in higher relative spleen weights in males at 42 d. Serum GLU concentrations were highest in males that received 3% lard rather than no added lard in the S1 diet. Serum low density lipoprotein cholesterol (LDLC) concentrations at 14 d were highest in females fed constant levels of lard at either 3 or 7% in both starter periods. It was concluded that added lard fed to randombred chickens at various times and levels in starter diets elicited responses in organ weight and serum LDLC and GLU concentrations that varied with the sex and age of the bird and were not consistently related to BW.

The effect of added complex carbohydrates or added dietary fiber on necrotic enteritis lesions in broiler chickens

Two trials utilizing two corn diets and four wheat diets were conducted. In Trial 2, all chicks were crop-infused at 9 d of age with Eimeria acervulina. In both trials, a broth culture of Clostridium perfringens was mixed with the diets for 3 consecutive d. Necrotic enteritis lesion scores were lowest in chickens consuming the corn diet with no C. perfringens and highest in chickens fed the wheat diets with C. perfringens. Chickens consuming a wheat diet with no added complex carbohydrates or added fiber exhibited the highest lesion score. Chickens on wheat diets with 4% new, ground, pine shavings had intestinal lesion scores intermediate to those of chickens that consumed the wheat or corn diets. Chickens consuming corn diets yielded the lowest lesion scores. Chickens provided diets containing either guar gum or pectin were not fully consumed and thus probably reduced the number of challenge organisms ingested.

Changes in gonadal weights, serum lipids, and glucose during maturation in the juvenile northern bobwhite quail (Colinus virginianus)

Changes in serum lipids, serum glucose, and gonadal development during maturation of Colinus virginianus were determined in two trials. In Trial 1, sex, BW, and serum concentrations of total cholesterol, high, low, and very low density lipoprotein cholesterol, triglycerides, and glucose were determined every 2 d from 2 to 14 d and weekly from 21 to 49 d. Relative ovary or testis weights between 14 and 49 d were determined weekly. Body weight increased and all measured serum constituents changed in males and females between 2 and 49 d; however, relative testis weight decreased between 14 and 49 d. In Trial 2, sex, BW, cholesterol, and relative ovary and testis weights were determined in birds at 56 and 63 d of age. The distinctness of external sexual phenotype and its relationship to BW, cholesterol, and relative gonadal weight were also determined at 56 and 63 d. Body weight increased and serum cholesterol decreased in both sexes between 56 and 63 d, but had no association with the distinctness of external sexual phenotype. It was concluded that the development of external sexual identity in male and female Northern Bobwhite quail prior to sexual maturity was not related to changes in BW, gonad weight, serum lipids, or serum glucose before 63 d of age.

Continuous infusion of adrenocorticotropin elevates circulating lipoprotein cholesterol and corticosterone concentrations in chickens

The purpose of the present study was to investigate the effects of elevated corticosterone (CORT) on circulating lipoprotein cholesterol during a 1-wk period. For this study, 15 commercial broilers were randomly assigned to one of three treatment groups. Group 1 served as the control (CON) and received no treatment, whereas Groups 2 and 3 received subcutaneous mini-osmotic pumps containing either physiological saline (PS) or adrenocorticotropin (ACTH), respectively. The ACTH was delivered at a rate of 8 IU/kg of BW/d. Blood samples were taken at Time 0 (before implants) and on Days 2, 4, and 7 postimplantation. Continuous infusion of ACTH increased plasma glucose, cholesterol, triglycerides, very low density lipoprotein cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and CORT during the postimplantation period. The group treated with ACTH also exhibited a decrease in BW during the last 2 sampling d. There were no differences in any of the serum constituents measured between CON and PS birds, which suggest that CON birds can serve as useful controls. These data suggest that birds given a continuous infusion of ACTH at 8 IU/kg of BW/d can experience changes in plasma lipoprotein cholesterol concentrations along with changes in other blood parameters and may serve as a useful model in accelerated lipoprotein production.

A new apolipoprotein B truncation (apo B-43.7) in familial hypobetalipoproteinemia: genetic and metabolic studies

We describe a new truncation of apolipoprotein (apo) B in a white kindred with familial hypobetalipoproteinemia (FHBL). Apo B-43.7, found in a daughter and her father, was due to a C --> T change in base position 6162 of the apo B gene converting the arginine (residue 1986) codon CGA to a stop codon TGA. Both subjects were heterozygotes, and both apo B-43.7- and apo B-100-containing particles were present in plasma. On density gradient ultracentrifugation (DGUC), approximately 30% to 40% of apo B-43.7 floated with very-low-density lipoprotein (VLDL)/intermediate-density lipoprotein (IDL)-density particles and 60% to 70% floated with high-density lipoprotein (HDL)-density particles. To assess the metabolism of apo B, 13C-leucine was infused and its rates of appearance in and disappearance from apo B-43.7- and apo B-100-containing particles were quantified by multicompartmental kinetic analysis. Apo B-100 entered plasma via VLDL with a production rate of 30 mg x kg-1 x d-1. Fractional catabolic rates (FCRs) for apo B-100 VLDL, IDL, and low-density lipoprotein (LDL) were 20.0, 16.0, and 0.46 pools x d-1, respectively. The production rate of apo B-43.7 was 9.6 mg x kg-1 x d-1, and FCRs for apo B-43.7 VLDL- and HDL-like particles were 12.0 and 1.8 pools x d-1, respectively. Approximately 30% of apo B-43.7 in HDL-density particles was derived from VLDL apo B-43.7, and about 70% appeared to enter the plasma as HDLs. The relatively low production rate of apo B-43.7 is compatible with previous reports that apo B truncations are produced at lower rates than their apo B-100 counterparts.

Effects of breeder hen age and dietary fat on embryonic and neonatal broiler serum lipids and glucose

In two experiments, the effects of dietary fat and breeder hen age on relative yolk sac weight (RYSW) and total serum cholesterol (CHOL), high (HDLC) and low (LDLC) density lipoprotein cholesterol, triglycerides (TRI), and glucose (GLU) were monitored in broiler embryos and chicks. In Experiment 1, embryos at 18 d of incubation and chicks at hatch were sampled from eggs laid by breeder hens at 26 (young), 36, and 48 wk of age. No dietary effects were noted in either experiment; however, chicks from young hens exhibited elevated serum CHOL, HDLC, LDLC, and lower GLU when compared with chicks from hens at either 36 or 48 wk of age. Additionally, embryos from young breeders displayed a lower RYSW at 18 d of incubation. Conversely, by hatch there was no difference in RYSW among offspring from different aged hens. In Experiment 2, newly hatched chicks were sampled from breeder hens at 36, 51, and 64 wk of age. Dietary effects were also not evident in this experiment; however, chicks from 51-wk-old breeders displayed the highest and lowest serum HDLC and TRI, respectively, compared to the other two age groups, whereas chicks from either 51- or 64-wk-old breeders exhibited higher levels of CHOL than those at 36 wk. Chicks from 64-wk-old breeders displayed an increase in LDLC when compared with the other two ages. These data suggest that serum concentrations of lipids and GLU, and RYSW in 18 d embryos and newly hatched chicks are influenced by hen age and not by added dietary fat.

Effects of oral ethanol on serum lipoprotein cholesterol in juvenile meat-type chickens

The effects of moderate, short-term ethanol (EtOH) intake on various physiological parameters in growth-selected, juvenile, meat-type chickens were determined. Ethanol (20%) was administered orally at 2 ml per kg of body weight three times daily between 21 and 28 days of age. Feed consumption, body weight, rectal temperature, relative weights of the thyroid, adrenal, pancreas, and liver, serum triglycerides, cholesterol, glucose, and high-density, low-density, and very low-density lipoprotein cholesterol concentrations were determined. Serum cholesterol, high-density lipoprotein cholesterol, glucose, and relative liver weight peaked across all treatments at 23 days of age. Males exhibited higher cholesterol and high-density lipoprotein cholesterol concentrations than females. Ethanol did not affect feed consumption, body weight, or relative liver weight, but decreased elevated concentrations of serum low- and very low-density lipoprotein cholesterol and triglycerides at 23 days of age. Short-term, oral administration of EtOH may be used to suppress elevated concentrations of low- and very low-density lipoprotein cholesterol and triglycerides in male and female growth-selected, juvenile, meat-type chickens without gross changes in the liver or in growth.

The effects of nonautoclaved and autoclaved water-soluble wheat extracts on the growth of Clostridium perfringens

Clostridium perfringens is the causative agent of necrotic enteritis, a commonly diagnosed disease in chickens that is also observed in turkeys and geese. Two trials were conducted to determine the in vitro effect of filter-sterilized, water-soluble wheat extracts on the growth of C. perfringens. The extracts were either nonautoclaved or autoclaved at 121 C for 40 min and were used to reconstitute thioglycolate broth media. Results of this study suggest that growth of C. perfringens is suppressed in vitro by inclusion of either extract. Glycosyl composition analysis revealed no significant differences in arabinose, xylose, or mannose content between the nonautoclaved and autoclaved extracts. Galactose, glucose, and total glycosyl content were significantly higher in the nonautoclaved extract.

Changes in serum lipid, lipoprotein and corticosterone concentrations during neonatal chick development

Broiler chicks were given a standard commercial starter diet from day 0 (day of hatch) to 9 days of age. Body weight and concentrations of the following serum constituents were measured daily: glucose (GLU), triglycerides (TRI), corticosterone (CORT), cholesterol (CHOL), and high (HDL) and low (LDL) density lipoproteins. Serum GLU and TRI increased at each sampling day to reach a peak on days 3 and 4, respectively, and then decreased thereafter. However, CHOL, HDL, and LDL decreased sharply by day 1 and then gradually decreased to day 5. Conversely, CORT peaked on day 1 and then decreased to day 4. It peaked again on day 5 and remained at that level throughout the remainder of the experiment. In summary, serum concentrations of all constituents measured fluctuated drastically between 1 and 5 days of age, with few changes occurring between days 6 and 9.

Effects of dietary thiouracil on thyroid activity, egg production, and eggshell quality in commercial layers

The effects of thyroid suppression induced during the rearing period by providing various dietary thiouracil (TU) regimens on plasma thyroxine (T4) concentrations, growth, and subsequent egg production (EP) and eggshell quality were determined in Single Comb White Leghorn chickens. Thiouracil was provided in the feed at levels of 0, .1, and .2% from 0 to 6 wk of age in Experiment 1, and at levels of 0, .05, and .1% from 6 to 16 wk of age in Experiment 2. In both experiments, T4 concentrations were reduced during TU treatment. However, T4 later became elevated at 12 and 20 wk in both dosage level groups in Experiment 1. Additionally, BW and egg weights were suppressed by both TU treatments, and EP was reduced up to Week 23 in the .1% TU-treated birds and through Week 25 in the .2% TU-treated birds. No effects on EP were noted in Experiment 2, but feed consumption (FC) was reduced during Week 6 in birds fed .05% TU and during Weeks 6, 10, and 19 in birds fed .1% TU. Both liver and thyroid weights were increased in .1% TU-treated birds relative to controls at Week 16. Eggshell quality was affected only in Experiment 2, in which birds given .05% TU had a higher relative conductance, or maximum rate of water loss, at Week 38 than 0 and .1% TU dosage levels, and .1% TU-treated birds had a higher breaking strength than 0 and .05% TU-treated birds at Week 22.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of dietary fat on growth performance, carcass composition, and feed efficiency in the broiler chick

In two experiments broiler chicks were fed nonisocaloric diets with either 0, 3, or 7% added lard. Megacaloric percentages of all major nutrients were the same in all diets. In Experiment 1 (broiler chicks 0 to 5 d of age), added dietary lard did not affect body, heart, spleen, or pancreas weight. Liver weight was suppressed by the inclusion of lard in the diet, yet liver composition changed, becoming higher in protein and lower in fat. Yolk sac weight decreased during the first 5 d posthatch, with the decrease being most pronounced by 3 d of age. There were no differences in feed consumption due to treatment in Experiment 1. In Experiment 2 (broiler chicks 6 to 11 d of age), added dietary fat resulted in differences in liver, body, and fecal excreta composition. Chicks given 7% added lard had lower liver fat throughout the trial than chicks fed no added lard. Additionally, these chicks had a higher body protein content at 6 and 7 d of age. However, body fat only increased in chicks fed 7% added lard by 11 d of age. Furthermore, chicks receiving 7% added lard had elevated fecal fat at Day 6, but did not consume more feed than chicks receiving 0 or 3% added lard. Additionally, chicks fed lard had lower liver weights than those fed 0% added lard.

Ultrasonography as a tool for monitoring in ovo chicken development. 1. Technique and morphological findings

Preliminary studies were performed to develop a method for using real-time, B-mode ultrasonography (US) to directly image the internal morphology of the chicken egg and developing embryo. Different soft tissue interfaces will reflect US waves differentially. These reflected waves, or echoes are then converted into a two-dimensional image of internal morphology. A major limitation of diagnostic US is its inability to penetrate through gas or hard tissue (bone, shell) interfaces. Methodology development to overcome the acoustic obstacle presented by the eggshell and air cell constituted the initial part of the preliminary study. An acoustical window was achieved by creating a 2-cm fenestration through the large end of the eggshell, then filling the air cell with sterile saline. Morphological features of the yolk and embryo were recorded at 0, 2, 6, 9, 14, and 17 days of incubation. The second part of the preliminary study explores whether the acoustic window, once created, could then be closed, and if closed, whether egg viability could be maintained. A second concurrent trial was conducted with 32 eggs that were fenestrated, imaged, recorded, reclosed, and incubated. Two methods of closure were attempted: one using dialysis membrane and tape; the other using an eggshell allograft. Hatchability was partially retained with both window closure methods.