Select 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors vary in their ability to reduce egg yolk cholesterol levels in laying hens through alteration of hepatic cholesterol biosynthesis and plasma VLDL composition

Effects of 3-Hydroxy-3-methylglutaryl-CoA Reductase Inhibitors on Cholesterol Metabolism in Laying Hens

This study aimed to investigate the effect of HMGCR inhibitors on egg yolk cholesterol content and its biological mechanisms. Four groups of 180-day-old laying hens (n = 8 cages/group, 6 laying hens/cage) were fed a corn/soybean-based diet (control) and the control diet supplemented with an HMGCR inhibitor at 60, 150, and 300 mg/kg for 4 weeks. The experimental results showed that adding HMGCR inhibitors of 150 mg/kg or more can significantly reduce the cholesterol content in the liver, yolk, serum, and pectoral muscles of laying hens. The RNA-seq results showed that compared with the control group, the addition of HMGCR inhibitors of 150 mg/kg or more to the diet significantly upregulated genes related to cholesterol synthesis in the liver, and the genes involved in steroid synthesis and metabolism, sterol synthesis and metabolism, and cholesterol synthesis and metabolism were all affected by the HMGCR inhibitors. In summary, adding HMGCR inhibitors of 150 mg/kg or more to the diet of hens can significantly reduce the cholesterol content in egg yolk. After the HMGCR inhibitors inhibited the activity of the liver HMGCR, they also altered the expression of genes related to cholesterol synthesis, bile acid synthesis, and cholesterol transport in the liver, and ultimately reduced cholesterol synthesis and cholesterol transport to the egg yolk.

Feeding laying hens docosa hexaenoic acid-rich microalgae oil at 40 g/kg diet causes hypotriglyceridemia, depresses egg production, and attenuates expression of key genes affecting hepatic triglyceride synthesis and secretion, but is rescued by dietary co-supplementation of high-oleic sunflower oil

The primary goal of this study was to investigate the effect of feeding White Leghorn hens graded levels of a docosahexaenoic acid (DHA)-rich microalgae oil (MAO) on productive performance and enrichment of eggs with very long-chain (VLC) omega-3 (n-3) polyunsaturated fatty acids (PUFA). Forty-nine-week-old hens (8 per diet) were fed the following diets for 28 d: 1) A corn-soybean meal-based diet with no supplemental oil (CON); 2) CON + 10 g/kg MAO; 3) CON + 20 g/kg MAO; 4) CON + 30 g/kg MAO; 5) CON + 40 g/kg MAO; 6) CON + 40 g/kg MAO + 20 g/kg high-oleic sunflower oil (HOSO); and 7) CON + 40 g/kg MAO + 40 g/kg HOSO. Diets 6 and 7 were included because we previously reported that co-feeding high-oleic acid oils with n-3 PUFA-containing oils attenuated egg yolk n-3 PUFA contents vs. feeding hens the n-3 oils alone. All data were collected on an individual hen basis. Egg VLC n-3 PUFA enrichment plateaued, in terms of statistical significance, at the 30 g/kg MAO level (266 mg/yolk). Hens fed 40 g/kg MAO had greatly attenuated measures of hen performance, marked liver enlargement, an altered ovarian follicle hierarchy, greatly lowered circulating triglyceride levels, and depressed hepatic expression of key genes involved in triglyceride synthesis and secretion. As compared to hens fed 40 g/kg MAO alone, feeding hens 40 g/kg MAO co-supplemented with HOSO (Diets 6 and 7) restored egg production, ovarian morphology, and all other measures of hen productive performance to CON levels, elevated plasma triglyceride levels, prevented liver enlargement, and increased the hepatic expression of key genes involved in triglyceride synthesis and secretion. In conclusion, MAO can greatly enrich hens' eggs with VLC n-3 PUFA, but its recommended dietary inclusion should not exceed 20 g/kg. This would allow for near-maximal yolk VLC n-3 PUFA enrichment without impairing hen productive performance, altering the ovarian follicle hierarchy or, based on the work of others, presumably imparting off-flavors in the egg.

Effects of Dietary Supplementation with Red Yeast (Sporidiobolus pararoseus) on Productive Performance, Egg Quality, and Duodenal Cell Proliferation of Laying Hens

Simple Summary

The present study investigated the effect of different levels of red yeast added to the diet of laying hens as a substitute for antibiotics. The aim of this study is to measure growth performance, egg quality, and small intestinal health of hens receiving this supplement at various levels during 22–60 weeks of age. The results indicate that supplementation with dietary red yeast has a positive effect on productivity and gut health; thus, we suggest administration of this additive as a substitute for antibiotics in laying hens.

Abstract

Nowadays, industrial poultry producers are more focused on the safety of their products, especially contaminants from feedstuffs such as mycotoxin and pesticides. The residue from animal production using antibiotic growth promoters (AGPs) may cause some problems with antimicrobial resistance in human and animals. Red yeast (Sporidiobolus pararoseus) has a cell wall consisting of β-glucan and mannan-oligosaccharides and pigments from carotenoids that may be suitable for use as a substitute for AGPs. The objective was to evaluate the effects of red yeast in laying hen diets on productive performance, egg quality, and duodenal health. A total of 22-week-old laying hens (n = 480) were divided into five groups: control diet (CON), AGP at 4.5 g/kg and red yeast supplementation at 1.0 (RY1.0), 2.0 (RY2.0) and 4.0 g/kg (RY4.0) of diet. The results show that the AGP, RY2.0, and RY4.0 groups had significantly higher final body weight compared with the other groups (p < 0.001). The red yeast supplementation improved the egg shape index (p = 0.025), Haugh unit (p < 0.001), and yolk color (p = 0.037), and decreased yolk cholesterol (p < 0.001). Diet with red yeast supplementation improved villus height to crypt depth ratio and crypt cell proliferations. In conclusion, red yeast supplementation at 2.0 g/kg of diet can substitute AGP in layer diet.

Analysis of Serum Biochemical Indexes, Egg Quality, and Liver Transcriptome in Laying Hens Fed Diets Supplemented with Gynostemma pentaphyllum Powder

Gynostemma pentaphyllum (GP), known as “southern ginseng”, can reduce the blood pressure and blood lipid levels. In this study, 300 layer chicks of one day old were divided randomly into three groups (control group (base diet), high addition group (base diet with 1% GP), and low addition group (base diet with 0.5% GP)). After 29 weeks, the growth performance, egg quality, and serum index were determined. Additionally, liver mRNA was identified using RNA-seq to investigate the molecular mechanisms. The results indicated that the serum total cholesterol and triglycerides decreased significantly in the GP addition group. The addition of GP increased the egg weight, Haugh unit and redness (a*) of the egg yolk color, and reduced the yolk cholesterol concentration. Moreover, 95 differentially expressed genes (DEGs) were screened between the control and GP addition group. GO and the KEGG analysis showed that the PPAR pathway was significantly enriched. Five fatty acid metabolism-related genes (FABP3, CYP7A1, ANKRD22, SCD1, and PCK1) were validated by qRT-PCR analysis, which confirmed the tendency of the expression. These DEGs in the PPAR pathway may be the key factors of GP affecting fatty acid metabolism. These results may provide a theoretical basis for further research and new insights into GP as a feed additive.

The effect of high monacolin K red yeast rice supplement on performance, egg quality, egg yolk cholesterol, plasma lipids and enzyme profile of laying hens

Context Reducing egg cholesterol has been a major goal of many researchers over four decades. Monacolin K, a 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitor, identical to the active ingredient in the prescription statin drug lovastatin, could be a promising feed supplement for layers. Aims To determine the effects of high monacolin K red yeast rice (RYR) supplement on feed intake, egg production, egg cholesterol content, plasma lipid and enzyme metabolites in laying hens. Methods Hyline brown layers were fed RYR supplement at 0, 0.2, 0.4, 0.8 and 1.6% of the diet for 6 weeks. Total and daily feed intake, egg production, egg weights and feed conversion ratio between the RYR treated groups and the control were compiled. Egg cholesterol and egg quality at the 3rd and 6th week of the feeding trial were analysed. Plasma lipids and enzymes were sampled towards the end of the trial. Key results Egg cholesterol were significantly lower (P &lt; 0.05) in the 0.8 and 1.6% RYR supplemented group. Supplementation with 0.8% RYR resulted in 11.16% reduction in egg cholesterol at the 3rd week with no further improvements with longer feeding. There were no significant differences (P &gt; 0.05) in total and daily feed intake, egg production, egg weights and feed conversion ratio (FCR) between the RYR treated and control group. Total plasma cholesterol and triglycerides were significantly lower (P &lt; 0.05) in the 0.8 and 1.6% RYR supplemented group when compared with the control group. RYR supplementation exert no significant differences (P &gt; 0.05) in plasma enzyme levels. Conclusions The present study suggests that RYR supplementation of 0.8% resulted in egg cholesterol reduction by 11.16% with no adverse effects on laying hens. Implications The feeding trial showed that RYR supplement can be used as a feed additive in layer diets to lower egg cholesterol, plasma cholesterol and triglycerides with no adverse effects on layer egg production and plasma enzymes over the feeding period.

Effects of dietary fats on egg quality and lipid parameters in serum and yolks of Shan Partridge Duck

The effects of different dietary fats with variable levels of polyunsaturated fatty acids (PUFAs) on egg quality of Shan Partridge Duck, serum, and yolk lipid parameters were examined in this study. A flock of 585 optimal produced ducks were selected and diets enriched with 0.5%, 1%, or 2% fish oil (F)/flaxseed oil (FL)/rapeseed oil (R)/tallow (T) plus basal diet were supplied through a 28-d period. Supplemental fat source and fat level had no effects on egg qualities. Proportions of yolk total cholesterol (TC), saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) were reduced (P < 0.001), while polyunsaturated fatty acids (PUFAs), ω-6 polyunsaturated fatty acids (n-6 PUFAs), ω-3 polyunsaturated fatty acids (n-3 PUFAs), Docosahexaenoic Acid (DHA), and Eicosapentaenoic Acid (EPA) were increased by fish oil, flaxseed oil, or rapeseed oil. Effects of supplementation increasing DHA and EPA were detected in F, FL, and R. Compared with C, fish oil significantly increased low-density lipoprotein cholesterol (LDL-C) in serum, flaxseed oil significantly reduced TC and increased very low-density lipoprotein cholesterol (VLDL-C), rapeseed oil significantly reduced TC and LDL-C in serum and increased VLDL-C, tallow significantly increased LDL-C. It is concluded that unsaturated fatty acids rich diets (fish oil, flaxseed oil, and rapeseed oil) might increase yolk PUFAs, reduce yolk cholesterol, and change serum lipid parameters without evident effect on egg qualities.

Plasma Drug Concentrations of Orally Administered Rosuvastatin in Hispaniolan Amazon Parrots (Amazona ventralis)

Atherosclerotic diseases are common in pet psittacine birds, in particular Amazon parrots. While hypercholesterolemia and dyslipidemia have not definitely been associated with increased susceptibility to atherosclerosis in parrots, these are important and well-known risk factors in humans. Therefore statin drugs such as rosuvastatin constitute the mainstay of human treatment of dyslipidemia and the prevention of atherosclerosis. No pharmacologic studies have been performed in psittacine birds despite the high prevalence of atherosclerosis in captivity. Thirteen Hispaniolan Amazon parrots were used to test a single oral dose of 10 mg/kg of rosuvastatin with blood sampling performed according to a balanced incomplete block design over 36 hours. Because low plasma concentrations were produced in the first study, a subsequent pilot study using a dose of 25 mg/kg in 2 Amazon parrots was performed. Most plasma samples for the 10 mg/kg dose and all samples for the 25 mg/kg dose had rosuvastatin concentration below the limits of quantitation. For the 10 mg/kg study, the median peak plasma concentration and time to peak plasma concentration were 0.032 μg/mL and 2 hours, respectively. Our results indicate that rosuvastatin does not appear suitable in Amazon parrots as compounded and used at the dose in this study. Pharmacodynamic studies investigating lipid-lowering effects of statins rather than pharmacokinetic studies may be more practical and cost effective in future studies to screen for a statin with more ideal properties for potential use in psittacine dyslipidemia and atherosclerotic diseases.

Feeding laying hens stearidonic acid-enriched soybean oil, as compared to flaxseed oil, more efficiently enriches eggs with very long-chain n-3 polyunsaturated fatty acids

The desaturation of α-linolenic acid (ALA) to stearidonic acid (SDA) is considered to be rate-limiting for the hepatic conversion of ALA to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in humans, rodents, and chickens. Thus, we hypothesized that feeding laying hens SDA, as a component of the oil derived from the genetic modification of the soybean, would bypass this inefficient metabolic step and result in the enrichment of eggs with EPA and DHA at amounts comparable to that achieved by direct supplementation of hens' diet with these very long-chain (VLC) n-3 polyunsaturated fatty acids (PUFAs). In a 28-d study, laying hens incorporated 0.132 mg, 0.041 mg, or 0.075 mg of VLC n-3 PUFAs into egg yolk for each milligram of ingested dietary ALA derived primarily from conventional soybean oil (CON), dietary ALA derived primarily from flaxseed oil (FLAX), or dietary SDA derived from SDA-enriched soybean oil, respectively. Moreover, the amounts of total yolk VLC n-3 PUFAs in eggs from hens fed the CON (51 mg), FLAX (91 mg), or SDA (125 mg) oils were markedly less than the 305 mg found in eggs from fish oil-fed hens. Unexpectedly, SDA appeared to be more readily incorporated into adipose tissue than into egg yolk. Since egg yolk FAs typically reflect the hens' dietary pattern, these tissue-specific differences suggest the existence of an alternate pathway for the hepatic secretion and transport of SDA in the laying hen.

Physiological performance of quails that underwent dietary and pharmacological manipulation of cholesterol

The present work evaluated whether dietary and pharmacological interference on cholesterol synthesis were capable of inducing alterations in blood and yolk cholesterol levels and the secretion of corticosterone metabolites. Forty-five 40-day-old quails were divided into three experimental groups: vegetal fat diet, 2% beef fat (tallow) diet and vegetal fat diet with simvastatin administration (3.13 mg/kg/day). During all experiments, the animal weights and food consumption were recorded and blood and faecal samples (days 0, 15, 30, 45 and 60), as well as eggs (days 30, 45 and 60), were collected. Analysis of serum and yolk cholesterol was performed and faecal corticosterone levels were measured. No differences were observed on blood cholesterol or faecal corticosterone between all treatments, despite a tendency of increased cholesterol in the group with the animal fat diet. However, quails submitted to an animal fat diet displayed an increase in yolk cholesterol at day 30 of the treatment and the egg yolks of quails treated with simvastatin exhibited a decrease in cholesterol content by the end of the treatment at 60 days. These results improved the knowledge regarding the physiology of quails and offered support to other studies concerning the consequences of the pharmacological treatment and the dietary manipulation of cholesterol levels.

The restricted ovulator chicken strain: an oviparous vertebrate model of reproductive dysfunction caused by a gene defect affecting an oocyte-specific receptor

A unique non-laying strain of chickens with heritable hyperlipidemia and aortic atherosclerosis was first described in 1974. Subsequent work established that the phenotype results from a naturally occurring point mutation in the gene specifying the very low density lipoprotein (VLDL) receptor, a 95-kDa membrane protein which normally mediates the massive uptake of the main circulating hepatically-synthesized yolk precursors, VLDL and vitellogenin. As a result, hens of the mutant strain termed "restricted ovulator" (R/O) have approximately 5-fold elevations in circulating cholesterol and triglyceride concentrations compared with normal layers, and hepatic lipogenesis and cholesterogenesis are markedly attenuated due to feedback inhibition. R/O hens also exhibit hyperestrogenemia, hypoprogesteronemia, elevated circulating gonadotropins, and up-regulated pituitary progesterone receptor mRNA and isoforms. The ovaries of R/O hens are abnormal in that they lack a follicular hierarchy and contain many small preovulatory follicles of various colors, shapes, and sizes. However, since R/O hens occasionally lay eggs, it is possible that endocytic receptors other than the VLDL receptor may be able to facilitate oocyte growth and/or that yolk precursor uptake can occur via a nonspecific bulk process. A mammalian model of impaired fecundity with abnormal lipoprotein metabolism also has been described, but different mechanisms are likely responsible for its reproductive dysfunction. Nevertheless, as our understanding of the molecular physiology and biochemistry of avian oocyte growth continues to expand, in part due to studies of the R/O model, new analogies may emerge between avian and mammalian systems, which ultimately could help to answer important questions in reproductive biology.

Egg production, faecal pH and microbial population, small intestine morphology, and plasma and yolk cholesterol in laying hens given liquid metabolites produced by Lactobacillus plantarum strains

1. Various dosages of metabolite combinations of the Lactobacillus plantarum RI11, RG14 and RG11 strains (COM456) were used to study the egg production, faecal microflora population, faecal pH, small intestine morphology, and plasma and egg yolk cholesterol in laying hens. 2. A total of 500 Lohmann Brown hens were raised from 19 weeks to 31 weeks of age. The birds were randomly divided into 5 groups and fed on various treatment diets: (i) basal diet without supplementation of metabolites (control); (ii) basal diet supplemented with 0·3% COM456 metabolites; (iii) basal diet supplemented with 0·6% COM456 metabolites; (iv) basal diet supplemented with 0·9% COM456 metabolites; and (v) basal diet supplemented with 1·2% COM456 metabolites. 3. The inclusion of 0·6% liquid metabolite combinations, produced from three L. plantarum strains, demonstrated the best effect in improving the hens' egg production, faecal lactic acid bacteria population, and small intestine villus height, and reducing faecal pH and Enterobacteriaceae population, and plasma and yolk cholesterol concentrations. 4. The metabolites from locally isolated L. plantarum are a possible alternative feed additive in poultry production.

Omega-3 fatty acid application reduces yolk and plasma cholesterol levels in Japanese quails

The aim of this study was to determine the effects of fish oil, rich in omega-3 fatty acids, on the cholesterol levels in egg yolk and plasma in Japanese quail. Additionally, the effects of these fatty acids on selected biochemical parameters, and yolk and quail weights were investigated. Thirty healthy laying Japanese quails were divided into two groups including control and omega-3 fatty acid treated group. Fish oil capsules were administrated orally to the quails in the omega-3 treated group every other day for 3 weeks. Yolk cholesterol level was found to be significantly lower in the omega-3 treated group compared to the control. Plasma cholesterol levels were lower; plasma calcium levels were higher at 3rd week in omega-3 fatty acid treated group than those in control. On the other hand, plasma phosphorus and glucose levels in omega-3 fatty acid group were significantly lower at 3rd week than those at the beginning of experiment. In conclusion, it was found that orally supplemented omega-3 fatty acid reduced the levels of cholesterol in egg yolk and plasma in quails.

Molecular characterization and expression of the cholesteryl ester transfer protein gene in chickens

The cDNA for cholesteryl ester transfer protein (CETP), a protein that catalyzes cholesteryl ester transfer between very low density and high density lipoproteins in plasma, was isolated from chicken liver. When the recombinant protein was overexpressed in HEK293 cells, cholesteryl ester transfer activity was observed in media and cell lysates. By Northern blot analysis, chicken CETP mRNA expression was detected in liver, brain, heart, and spleen. Changes in chicken CETP mRNA expression and plasma CETP activity with nutritional state were examined and found to increase following dietary supplementation with cholesterol in a similar way as in humans. Both the hepatic CETP mRNA levels and plasma CETP activity were significantly lower in mature (i.e egg-laying) hens than in immature female chickens, but were unaffected by age in male animals. Similar changes to those observed in female chickens were observed upon estradiol administration of males. The present study is the first to report the molecular characterization of an avian CETP, and the impairments of CETP gene and activity, which might be regulated by estrogen, play an important role in egg production in laying hens, demonstrating species-specific differences in the lipid metabolism of avian and mammalian species.

Effects of atorvastatin on lipid metabolism in normolipidemic and hereditary hyperlipidemic, non-laying hens

As a result of a hereditable point mutation in the oocyte very low density lipoprotein (VLDL) receptor, sexually mature restricted ovulator (RO) female chickens (Gallus gallus), first described as a non-laying strain, exhibit endogenous hyperlipidemia and develop atherosclerotic lesions. In a 20-day study, RO hens and their normolipidemic (NL) siblings were fed either a control diet, or the control diet supplemented with 0.06% atorvastatin (AT), a potent 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) inhibitor. Compared to NL hens, RO birds exhibited greatly elevated baseline plasma total cholesterol (CHOL) and triglyceride (TG) concentrations (1.56 vs. 4.55 g/l and 30.7 vs. 138.4 g/l, respectively). AT attenuated plasma CHOL and TG concentrations by 60.3% and 70.1%, respectively, in NL hens and by 45.1% and 34.3%, respectively, in RO hens. Messenger RNA levels of several key genes involved in hepatic VLDL assembly were suppressed in RO vs. NL hens, but were unaffected by AT. In contrast, AT elevated liver HMGR mRNA levels in NL and RO birds, but only NL hens exhibited an AT-associated increase in hepatic HMGR immunoreactive protein levels. Down-regulation of HMGR gene expression due to higher baseline levels of circulating CHOL may explain why RO birds responded less robustly than NL hens to AT administration.

Oral administration of pravastatin reduces egg cholesterol but not plasma cholesterol in laying hens

The effect of different 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGR)-inhibitors (statins) on plasma and egg cholesterol in laying hens was investigated. Forty-four ISA brown layers were fed lovastatin, simvastatin, or pravastatin at 0.03 or 0.06% for 4 wk. Cholesterol levels in plasma, liver, and egg yolk as well as hen laying performance were studied. Egg weight was significantly lowered with all statin treatments, although egg production was relatively unaffected. Total plasma cholesterol was significantly reduced by 0.06% lovastatin, 0.03% simvastatin, and 0.06% simvastatin, in agreement with previous reports, whereas pravastatin had no effect. In contrast, liver cholesterol concentrations showed a significant decrease in response to 0.03 and 0.06% pravastatin, implying selective regulation of liver cholesterol synthesis. Furthermore, oral administration with 0.06% pravastatin reduced egg cholesterol levels by almost 20% compared with the control diet. This suggests that pravastatin, unlike other classes of statin, may be a good candidate for commercial production of low cholesterol eggs with limited impact on hen physiology and egg production.

Changes in mRNA expression of 3-hydroxy-3-methylglutaryl coenzyme A reductase and cholesterol 7 alpha-hydroxylase in chickens

3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) and cholesterol 7 alpha-hydroxylase (CYP7A1), essential enzymes of cholesterol synthesis and excretion, respectively, were isolated from a chicken liver cDNA library. When their recombinant proteins were overexpressed in HNK293 cells, corresponding enzyme activities were observed. The complete open reading frames of MHGR and CYP7A1 contained (i) 2625 base pairs (bp), predicting a protein of 875 amino acids, and (ii) 1539 bp, predicting a protein of 513 amino acids, respectively. By Northern blot analysis, chicken HMGR mRNA expression was detected in most tissues examined, however, the highest levels were found in liver, brain and ileum. CYP7A1 mRNA was detected only in the liver. Changes in chicken HMGR and CYP7A1 mRNA expression with nutritional state were examined and were shown to respond to certain nutritional treatments, i.e. fast refeeding and cholesterol supplementation. HMGR and CYP7A1 mRNA levels were significantly increased with maturation (i.e. egg producing), when compared to immature chickens. However, these stimulations were not associated with estrogen, although this does enhance triacylglycerol and very low density lipoprotein secretion by the chicken liver. The present study is the first to report the molecular characterization of HMGR and CYP7A1, key enzymes of cholesterol metabolism in avian species.

Assessment of egg nutrient compositional changes and residue in eggs, tissues, and excreta following oral administration of atorvastatin to laying hens

Laying hens were fed a control diet alone or with 0.06 g of atorvastatin, a synthetic 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, per 100 g of diet for 20 days. Compared to controls, egg yolks from treated hens contained greater amounts of amino acids and reduced levels of total fatty acids and cholesterol. In contrast, egg albumen amino acid contents were unaffected by dietary treatments. In a residue study, seven hens each received a single oral dose of approximately 20 microCi of [(14)C]atorvastatin. Approximately 71% of the radioactivity was recovered in the excreta and liver, whereas virtually no radioactivity was detected in kidney, heart, muscle, bile, plasma, or egg albumen at 15 days postdosing. Yolk radioactivity peaked at 4 days postdosing in six of the seven birds and was absent in eggs laid after day 10. Reminiscent of that of certain antibiotic drugs, the atorvastatin egg residue pattern appeared to coincide with the physiological pattern of daily yolk accretion within the ovary.