The effect of male and female supplementation of L-carnitine on reproductive traits of white leghorns

Previous work in our laboratory showed that including 125 ppm of l-carnitine in the diets of roosters increased sperm concentration. The objective of this experiment was to determine whether reproductive efficiency could be improved by feeding l-carnitine to both parents over that of feeding l-carnitine to only the male or female. Diets formulated to contain 0 or 125 ppm of l-carnitine were fed to male and female birds from hatch until 37 wk of age. Eighty-four roosters were used, with the semen of 2 roosters constituting an experimental unit. Pools of semen from either l-carnitine-supplemented or control roosters were artificially inseminated into each of 288 hens with 23.5 muL of semen at weekly intervals, in a 2 x 2 factorial arrangement, resulting in a mean insemination dose of 1.2 and 1.1 x 10(8) sperm/hen for l-carnitine and control hens, respectively. Dietary l-carnitine, as compared with the control diet, increased egg yolk l-carnitine concentration (P = 0.001), decreased hatchling yolk sac weights (P = 0.0001), decreased yolk sac lipid content at hatch (P = 0.01), and culminated in compositional changes of yolk fatty acids, but it did not affect hatch rate, egg production, and egg traits. Although supplementing diets with l-carnitine improved sperm concentration, it did not result in a subsequent improvement in hatch rate, most likely because of the high numbers of sperm that were inseminated artificially in both the control and l-carnitine-supplemented hens. The higher concentrations of l-carnitine in the yolk of hatching eggs obtained from hens consuming l-carnitine as compared with controls may have encouraged the utilization of fat by developing embryos, as indicated by the decreased hatchling yolk sac weights and yolk sac lipid content, perhaps leading to the selective utilization of linoleic (C18:2n-6) and alpha-linolenic (C18:3n-3) acids for growth and development over myristic (C14:0) and oleic (C18:1n-9) acids.

The effect of in ovo injection of L-carnitine on hatchability of white leghorns

Two experiments were conducted to determine if L-carnitine injected in ovo affected hatchability. Eggs of experiment 1 were injected with sterilized saline (0.85%) or L-carnitine (0.25, 0.50, 1.00, or 2.00 micromol dissolved in saline). An additional group of eggs served as noninjected controls. Hatchabilities were unaffected by treatment (94% for noninjected controls; 94% for saline injected eggs; and 87, 87, 88, and 88% for eggs injected with 0.25, 0.50, 1.00, or 2.00 micromol of L-carnitine, respectively; SEM = 1). Yolk sac weights retrieved from hatchings that were subjected to 0, 0.25, or 0.50 micromol of L-carnitine as embryos through in ovo injection were 3.9, 3.8, and 3.6 g, respectively (SEM = 0.1, P = 0.71). Eggs used in experiment 2 were injected with a wider dosimetry of l-carnitine. Fertile eggs were injected with sterilized saline (0.85%) or L-carnitine (0.05, 0.5, 5, or 10 micromol dissolved in saline). An additional group of eggs served as noninjected controls. Chick BW and % hatch were unaffected by treatment (76% for noninjected controls; 74% for saline injected eggs; and 77, 77, 68, and 76% for eggs injected with 0.05, 0.5, 5, or 10 micromol of L-carnitine, respectively; SEM = 3). In ovo injection of L-carnitine into fertile chicken eggs at 17 or 18 d of incubation did not affect hatchability, yolk sac weight, or BW.

The Effect of Dietary l-Carnitine on Semen Traits of White Leghorns

A previous study conducted in our laboratory showed that feeding 500 ppm of dietary L-carnitine to young and aging White Leghorns for 5 wk improved sperm concentration and reduced sperm lipid peroxidation during the last half of supplementation. The current study examined the effect of feeding dosimetric as well as lower levels of L-carnitine for longer durations on semen traits of White Leghorns. In experiments 1 and 2, White Leghorns consumed diets supplemented with 0, 125, 250, or 500 mg of L-carnitine/kg of feed. For experiment 1, an 8-wk trial was conducted with 48 White Leghorns from 46 to 54 wk of age. For experiment 2, a 17-wk trial was conducted with 96 White Leghorn roosters from 46 to 63 wk of age. For experiment 3, 84 roosters were provided for ad libitum consumption a diet formulated to contain 0 or 125 ppm of L-carnitine beginning at hatch until 37 wk of age. Long-term consumption of 125 ppm of L-carnitine beginning at hatch was the only dietary treatment that sustained a persistent increase in sperm concentration. These results suggest that L-carnitine's antioxidant influence on sperm production begins before the onset of sexual maturity.

Effect of hypothyroidism on the blood lipid response to higher dietary fat intake in mares

Blood lipid and lipoprotein concentrations were measured and compared between euthyroid and thyroidectomized mares on low-fat or high-fat diets to test the hypothesis that hypothyroidism alters the blood lipid response to higher dietary fat intake. Four healthy adult mares and four adult mares that had been thyroidectomized 3 to 6 mo earlier were placed on low-fat or high-fat diets according to a replicated 2 x 2 Latin square design consisting of two 5-wk feeding periods separated by a 2-wk washout interval. Plasma lipid concentrations were measured at 0, 3, 4, and 5 wk, and plasma lipase activities were measured at the end of each 5-wk feeding period. Compared with euthyroid mares (0.46 ng/mL [range 0.34 to 0.68 ng/mL T3], and 21.5 ng/mL [range 18.1 to 25.1 ng/mL T4], respectively), median serum concentrations of T3 and T4 were lower (P = 0.029 and P = 0.021, respectively) in thyroid-ectomized mares (0.26 ng/mL [range 0.23 to 0.26 ng/ mL T3], and undetectable T4). Serum T4 concentrations were below the limits of detection in thyroidectomized horses. Alterations in body weight over 5 wk did not differ between groups. Mean plasma very low density lipoprotein (VLDL) and triglyceride (TG) concentrations were higher (P = 0.045 and 0.034, respectively) in hypothyroid mares (55.42 +/- 35.05 mg/dL and 52.83 +/- 34.46 mg/dL, respectively) compared with euthyroid mares (28.28 +/- 13.76 mg/dL and 23.53 +/- 9.84 mg/dL, respectively). Mean plasma total cholesterol (TC) concentrations increased from 88.73 +/- 25.49 mg/dL at baseline to 103.93 +/- 24.42 mg/dL after 5 wk on the low-fat diet, but increased by a greater magnitude (P = 0.006 diet +/- time interaction) in mares that were on the high-fat diet (81.05 +/- 17.24 mg/dL and 123.84 +/- 32.27 mg/ dL, respectively). Mean plasma TC concentrations were higher (P = 0.099) in hypothyroid mares (116.16 +/- 32.89 mg/dL) than in euthyroid mares (89.56 +/- 14.45 mg/ dL). Higher post-heparin plasma lipoprotein lipase and hepatic lipase activities (P = 0.012 andP = 0.017, respectively) were detected in mares that were on the high-fat diet (2.66 +/- 0.91 micromol FA x mL(-1) x h(-1) and 2.95 +/- 0.49 micromol FA x mL(-1) x h(-1), respectively) vs. a low-fat diet (1.75 +/- 0.55 micromol FA x mL(-1) x h(-1) and 2.27 +/- 0.59 micromol FA x mL(-1) x h(-1), respectively). We conclude that plasma VLDL and TG concentrations are elevated in hypothyroid mares, but the blood lipid response to higher dietary fat intake is not influenced by hypothyroidism.

The effects of hen vocalizations on chick feeding behavior

The purpose of this study was to determine if playing hen calls at the feeder affects broiler chick productivity and welfare. Hatched chicks (n = 832) were equally placed into 16 pens. Broilers in 8 treated pens received 3 min of hen-feeding calls once each hour during the first 9 d of age; broilers in the other 8 pens received no recorded hen vocalizations during the same period. After d 9, recorded hen vocalizations ceased and all birds were treated identically. Through 9 d of age, chicks receiving recorded hen vocalizations had improved (P < or = 0.05) feed conversion ratios, and these chicks weighed more (139.12+/-1.52 g vs. 133.17+/-1.59 g for control chicks; P < or = 0.01). The behavior data showed that on d 1, 4, and 7, more (P < or = 0.05) chicks receiving recorded hen vocalizations were found within 0.61 m of the speaker than control chicks. Following recorded hen vocalization cessation on d 9, birds and feed were weighed on 17, 24, 31, and 38 d of age, and carcass yield was measured on d 40. There were no differences in BW, feed efficiency, or carcass yield after recorded hen vocalization ceased. These data suggest that after d 9, differences became nonsignificant, corresponding to when recorded hen vocalization stopped. Behavior data demonstrated that chicks appear to be attracted when stimulated with recorded hen vocalizations, thus remaining in close proximity to the speaker. Evidence suggests that hen vocalization improves production and attraction to hen vocalization with known improvements in BW and feed conversion during the first 9 d posthatch.

Utilization of energy and amino acids of spray-dried egg, plasma protein, and soybean meal by ducks

A study was conducted to determine AMEn, TMEn, apparent amino acid digestibility (AAAD), and true amino acid digestibility (TAAD) of spray-dried egg (SDE), plasma protein (PP), and soybean meal (SBM). AMEn and TMEn values for ducks fed SDE were higher (P < or = 0.001) than for ducks fed PP, which were higher than SBM. The AMEn values were 5.048, 3.230, and 2.605 kcal/g for SDE, PP, and SBM, respectively, with TMEn values of 5.373, 3.555, and 2.930 kcal/g, respectively. Spray-dried egg, PP, and SBM were similar in apparent digestibility of the indispensable amino acids except for methionine, histidine, and valine. Apparent methionine digestibility in SDE (95.5%) was higher (P < or = 0.01) than PP (88.3%) or SBM (91.3%). Apparent digestibilities of dispensable amino acids were similar for SDE, PP, and SBM except proline and alanine. Apparent alanine digestibility in SDE (89.9%) was higher (P < or = 0.05) than in SBM (85.7%). True digestibilities of indispensable amino acids were similar in SDE, PP, and SBM except for methionine, histidine, and valine. True methionine digestibility was higher (P < or = 0.05) for SDE (97.0%) than for PP (89.8%) or SBM (92.7%), with PP and SBM being similar. True histidine and valine digestibilities were significantly lower for SDE (P < or = 0.05) than for PP or SBM. True digestibilities of the dispensable amino acids were also similar in SDE, PP, and SBM except for proline and alanine. This study demonstrates that the energy value of SDE is greater than that of PP or SBM.

Evaluating the performance and acceptance of teleconference instruction versus traditional teaching methods for undergraduate and graduate students

Institutions are currently seeking alternative ways to deliver a full-line of course materials without acquiring additional staffing. Hence, faculty is charged with creating alternative ways to deliver or offer course content to students. The purpose of this study was to evaluate undergraduate and graduate performance and perception of teleconferencing versus traditional blackboard lectures. In the undergraduate course, we discovered that students performed equally as well on exams and provided favorable reviews of the course; however, the acceptance of this new format is lacking given the enrollment and number of students dropping, e.g., 30 to 40% reduction in the course before semester's end. On the other hand, students taking the graduate course appear to accept the technology well with consistent enrollments and achievement in course content. In summary, using teleconferencing as a way to teach students may be better suited for graduate students when compared to undergraduates.

The effect of dietary ascorbic acid on semen traits and testis histology of male turkey breeders

A 9-mo field trial was conducted to evaluate the effects of dietary L-ascorbic acid (AA) on semen traits of 144 male turkey breeders. Dietary AA treatments were initiated when birds were 30 wk of age. Semen and blood collection began at 32 wk of age. Three treatments with four pens per treatment and 12 birds per pen were fed 0, 75, and 150 mg/kg AA during the first 4 mo of their reproductive cycle. Levels of AA were doubled in the supplemented diets to 150 and 300 mg/kg during Months 5 to 9. Semen traits and blood AA were unaffected by dietary AA. When birds were 65 wk of age, testes were removed from 12 birds per treatment for histological analysis. Multinucleated giant cells (MCG), indicative of degeneration, were observed in the testes of 7 of the 12 control birds but were absent from AA-supplemented birds (P < 0.02). The antioxidant properties of AA may delay formation of these degenerative cells. In conclusion, dietary AA levels employed in the current study did not affect semen traits or testis weight but were associated with reduced formation of MGC in the testes of 65 wk-old breeder toms.

Liver lipid accumulation in duck embryos and hatchlings change with parental age

The purpose of this study was to investigate the effects of duck breeder age on liver lipid accumulation and yolk absorption and utilization in duck embryos (day 25 of incubation) and newly hatched ducklings. One breeder flock was monitored at 24 (young breeders), 31 (mature breeders and near peak egg production) and 47 (post peak egg production) weeks of age. Electron microscopy images of duck embryo liver slices revealed a significant change in hepatic lipid accumulation as a function of breeder age. More specifically, as breeder age increased both the relative number of liver lipid droplets as well as the size of the lipid droplets increased in duck embryos (day 25 of incubation). At hatch, however, newly hatched ducklings from 31-week-old breeders exhibited the lowest number as well as the smallest sized lipid droplets when compared to ducklings from 24 or 47-week-old breeders. The trend in yolk absorption at day 25 as a function of breeder age paralleled that in liver lipid accumulation. That is, day 25 maintained a higher percentage of unabsorbed yolk when compared to embryos from 31- or 47-week-old breeders. In contrast to breeder age, time of incubation (day 25 vs. day 28 or hatch) had little effect on yolk fatty acid profiles when compared to breeder age. Although there were no clear trends in yolk fatty acid usage among the various ages of breeders, newly hatched ducklings from 31-week-old breeders did have a significantly higher proportion of 18:2 n6 compared to those from breeders at 24 or 47 weeks of age. These data would suggest that breeder age subsequently affects the relative number and size of liver lipid droplets in embryos and newly hatched ducklings.

Market age live weight, carcass yield, and liver characteristics of broiler offspring from breeder hens fed diets differing in fat and energy contents

The effects of energy level, fat type, and fat level in breeder hen diets on subsequent offspring market age live BW, carcass yield, and liver characteristics from breeder hens at 29 and 36 wk of age were evaluated. At 22 wk of age, six dietary treatments were imposed. Dietary treatments contained: 1) 3.0%, added poultry fat (PF) and 467 (high energy) kcal/hen per day at peak production (CPP), 2) no added fat and high energy, 3) 3.0% added PF and 430 (low energy) CPP, 4) no added fat and low energy, 5) 1.5% added PF and 449 (moderate energy) CPP, and 6) 3.0% added corn oil (CO) and moderate energy. Breeder age influenced Day 43 broiler live BW, percentage total carcass and front-half yields, and liver moisture contents. Furthermore, wet and dry liver weights were higher in female broilers compared to those of male broilers from 29-wk-old breeder hens. Live BW was higher in broilers from hens fed low-energy diets compared with moderate-energy diets and 3.0% compared to 1.5% PF diets. Percentage liver DM was higher in females compared to male broilers from hens fed 3.0% CO and moderate energy and was highest in male and female broilers from hens fed 1.5% PF and moderate energy. Percentage wet liver weight and liver DM were higher and liver moisture content was lower in broilers from hens fed 1.5% compared to 3.0% PF diets. Overall, energy and fat levels in breeder diets had subsequent influences on market age weight and liver characteristics of broilers.

Breeder age influences embryogenesis in broiler hatching eggs

The effects of dietary fat and broiler breeder age on egg and embryo characteristics during incubation were investigated. Breeders were fed diets containing no added fat or 3.0% added poultry fat (PF) for peak energy intakes of 430 and 467 kcal/hen day (pC/d), or 1.5% PF or 3.0% corn oil at 449 pC/d. Feeding of diets was initiated at 22 wk, and eggs were collected for incubation at 27 and 36 wk of age. Percentage incubational egg weight loss was determined between day of set and Days 6, 12, and 18. Percentage wet and dry embryo weights, embryo moisture content, and eggshell weights were determined at 6, 12, and 18 d of incubation. Percentage yolk sac weight and wet and dry liver weights and moisture content were determined on Days 12 and 18. Percentage gall bladder weight was determined on Day 18. There were no observed effects due to breeder diet. However, eggshell weight at Days 6, 12, and 18 was higher in 27-wk-old hens compared with 36-wk-old hens. Conversely, egg weight loss between Day 0 and Days 6, 12, and 18 and yolk sac weight across Days 12 and 18 of incubation were lower in eggs at 27 wk of age compared with 36 wk. At Day 18, dry embryo weight was higher and wet liver weight was lower at 27 wk compared with 36 wk. A slower rate of DM accumulation in embryos at Week 36 compared to Week 27 was associated with increased incubational water loss and decreased embryo moisture content, eggshell percentage, and yolk sac absorption rate. These data demonstrate that changes in eggshell characteristics with broiler breeder age can alone impact yolk uptake, growth, and body composition in subsequent embryos.

Effects of conjugated linoleic acid. 1. Fatty acid modification of yolks and neonatal fatty acid metabolism

The purpose of this study was to evaluate the effects of conjugated linoleic acids (CLA) on neonatal fatty acid metabolism. In this study, layer hens (n = 40) were divided into four equal groups and subjected to the following treatments. Group A served as the control group, Group B received 1 g CLA every other day, Group C received 1 g CLA every 4th d, and Group D was sham-supplemented with 1 g safflower oil every other day. After 4 mo of feeding, Group B hens exhibited an increase in BW and egg size; however, there were no differences noted in feed consumption among the various treatment groups. At the same time, hens were inseminated with a constant dose of pooled rooster semen to evaluate changes in chick liver and yolk fatty acid metabolism during neonatal growth. At hatch and through 6 d of age, there were no significant differences in breakout data (fertility and numbers of early-, mid-, or late-dead chicks) or chick BW, respectively. However, Group B chicks exhibited an increase in liver 18:3n3 and 22:1n9 and a decrease in 20:3n6 and 22:5n3 fatty acids when compared with chicks from Groups A and D. Also noted for Group B chicks, yolk 18:0 fatty acid was higher than that for Group A and D chicks. These results suggest that CLA alters lipid metabolism in growing chicks.

Effects of conjugated linoleic acid. 2. Embryonic and neonatal growth and circulating lipids

The present study was designed to investigate the effects of conjugated linoleic acid (CLA) on yolk usage and circulating very low density lipoproteins (VLDL) during incubation (Day 15) and through 6 d post-hatch. Eggs enriched with CLA were obtained from hens subjected to the following treatments. Group A hens served as the control group, Group B hens received 1 g CLA every other day, Group C hens received 1 g CLA every 4th d, and Group D hens were sham-supplemented with 1 g safflower oil every other day. Enrichment with CLA did not effect fertility, hatch of fertile, BW, or yolk-free BW of embryos or chicks. However, there were significant changes in relative yolk sac weight (RYW) and composition of circulating VLDL particles. Across all dietary treatments (Groups B, C, and D), 15-d embryos had smaller RYW compared with Group A embryos; this difference remained through 2 d posthatch. During that period (15 d of incubation through 2 d posthatch), however, embryos and chicks from Group B hens exhibited a unique absorption pattern such that little to no yolk was utilized between hatch and 2 d posthatch, a period normally characterized by high yolk lipid utilization. Similar to the RYW effects, VLDL particles were also altered by hen-induced treatment. Specifically, at hatch, chicks from Group A hens had the highest percentage of triglycerides (TG) within their VLDL particles compared with chicks from hens under all other treatments. This trend in VLDL particles was continued at 4 d posthatch. The present study demonstrates that CLA enrichment of eggs alters relative yolk sac absorption and the composition of circulating VLDL particles.

Effects of breeder age and dietary fat source and level on broiler hatching egg characteristics

The effects of breeder age and added dietary fat source and level on broiler hatching egg characteristics were evaluated. Diets included no added fat (NAF) or 3.0% added poultry fat (PF) for peak energy intakes of 430 and 467 kcal/hen-day (PCD) or 1.5% PF or 3.0% corn oil (CO) at 449 PCD. As added dietary fat was changed from CO to PF, the percentage of unsaturated dietary fatty acids, including linoleic acid, decreased. Feeding of experimental diets was initiated when breeders were 22 wk old. Total fresh egg weight; eggshell weight; percentages of yolk (PYK), albumen (PAB), and eggshell (PSHL) weights; and yolk:albumen ratio were measured at various weeks between 26 and 47 wk of age. Egg weight increased progressively with hen age. Significant increases in yolk:albumen ratio occurred between Weeks 26 and 31 and between Weeks 31 and 35. Low (430 PCD) dietary energy levels significantly reduced PYK at 35 wk and increased PAB across breeder age. Eggshell weight was lower in birds fed moderate (449 PCD) compared to low energy levels at Week 26, moderate compared to high (467 PCD) energy levels at Week 41, and PF compared to CO across fat level at Week 31. At Weeks 31 and 41, PSHL was increased by the use of 3.0% PF compared to 1.5%, and PSHL was increased at Weeks 26 and 41 by using added PF compared to CO across fat level. Increased dietary energy decreased PAB and the use of added dietary CO rather than PF decreased PSHL in broiler breeders between 26 and 47 wk of age.

Effects of dietary fat type and level on broiler breeder performance

The effects of added dietary fat type and level on broiler breeder performance were evaluated in two trials. In Trial 1, diets included no added fat (NAF) or 3.0% added poultry fat (PF) for individual bird energy intakes of 430 and 467 kcal/d at peak production (PCD), or 1.5% PF or 3.0% corn oil (CO) at 449 PCD. In Trial 2, diets contained NAF, 1.5 or 3.0% added CO or PF, or 3.0% lard (LA) for peak energy intakes of 463 PCD. All diets in Trial 2 were isocaloric and isonitrogenous. Feeding of experimental diets was initiated when breeders were 22 wk old in both trials, and hen BW was measured at various weeks between 22 and 47 wk in Trial 1 and between 27 and 65 wk in Trial 2. Egg production, egg weight (EW), eggshell quality, and hatchability were recorded at various weeks between 24 and 48 wk in Trial 1 and between 27 and 64 wk in Trial 2. Body weights and EW increased progressively, and eggshell quality fluctuated variably with age. Egg production peaked between Weeks 32 and 35, and hatchability was significantly depressed at Week 63. Egg weight and hatchability were not affected by dietary treatment; however, BW increased with energy level in the diet between Weeks 27 and 47. Body weight was also higher in birds fed 1.5 or 3.0% added fat compared with NAF and was higher in birds fed LA compared with CO at the 3.0% level. Egg specific gravity and shell weight per unit of surface area at Week 41 were increased by feeding low or high energy compared with moderate energy, and relative eggshell conductance was increased by using moderate compared with high energy diets and by feeding 1.5% PF compared with 3.0% PF. Egg specific gravity was increased by PF when compared with CO across fat level at Weeks 26 and 47 and by LA when compared with PF across fat level and breeder age. These data suggest that certain dietary energy and fat regimens may affect BW and eggshell quality without associated effects on EW and hatchability at various breeder ages.

Embryo and yolk compositional relationships in broiler hatching eggs during incubation

Developmental relationships between yolk, embryo body, and embryo liver compositions during incubation were determined in two trials. In Trial 1, embryo body moisture, fat, and CP contents and embryo liver moisture and fat contents were determined. In Trial 2, relative yolk weights, moisture, fat, and fatty acid contents, relative wet and dry embryo weights and moisture contents, and relative wet and dry liver weights and moisture contents were determined. In Trial 1, embryo moisture decreased sigmoidally between Days 6 and 21, whereas embryo fat increased between Days 12 and 21 of incubation; embryo CP displayed sequential fluctuations throughout incubation. However, an overall significant decrease in embryo CP occurred between Days 6 and 21. Liver fat content increased between Days 12 and 21, whereas liver moisture decreased through Day 18, with a subsequent increase by Day 21. In Trial 2, relative yolk weight and moisture content decreased, whereas percentage yolk lipid content increased between Days 6 and 15. Relative wet and dry embryo weights changed in a similar manner, with rapid increases between Days 12 and 18 of incubation. Embryo moisture and CP were negatively correlated to embryo fat content. Furthermore, relative embryo and liver DM were related to yolk palmitic acid concentration, whereas yolk oleic acid was correlated only with liver DM. In conclusion, embryos and their livers displayed differential accumulations of moisture and DM during incubation, and these differences exhibited distinctive associations with various yolk fatty acids.

Effect of hypothyroidism on blood lipid concentrations in horses

OBJECTIVE

To measure and compare concentrations of selected blood lipids before and after thyroidectomy in horses.

ANIMALS

5 healthy adult mares.

PROCEDURE

Mares were confirmed to be euthyroid. Thyroidectomy was performed, and hypothyroidism was confirmed. Selected blood lipid variables were measured before hypothyroidism was induced and weekly for 4 weeks after induction. Plasma concentrations of very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), serum triglyceride (TG), total cholesterol (TC), and nonesterified fatty acid (NEFA) were measured. The composition of VLDL and LDL also was examined.

RESULTS

Mean plasma concentrations of VLDL and LDL increased significantly after thyroidectomy. By 4 weeks after thyroidectomy, a ninefold increase in mean plasma concentration of VLDL and a threefold increase in LDL, compared with baseline values, were detected. After thyroidectomy, mean percentage of TG in VLDL increased significantly, whereas free cholesterol and cholesterol ester content decreased. Mean percentage of TG in LDL also increased by 3 to 4 weeks after thyroidectomy. Serum concentrations of TG and TC increased, whereas serum NEFA concentration decreased.

CONCLUSIONS

Hypothyroidism significantly alters blood lipid concentrations of horses. After thyroidectomy, markedly high VLDL concentration, appearance of TG-rich VLDL, increased serum concentrations of TG and TC, and decreased blood concentration of NEFA were evident.

CLINICAL RELEVANCE

Examination of blood lipid concentrations of horses may be useful for detecting naturally acquired hypothyroidism.

Truncated apo B-70.5-containing lipoproteins bind to megalin but not the LDL receptor

Apo B-100 of LDL can bind to both the LDL receptor and megalin, but the molecular interactions of apo B-100 with these 2 receptors are not completely understood. Naturally occurring mutant forms of apo B may be a source of valuable information on these interactions. Apo B-70.5 is uniquely useful because it contains the NH2-terminal portion of apo B-100, that includes only one of the two putative LDL receptor-binding sites (site A). The lipoprotein containing apo B-70. 5 (Lp B-70.5) was purified from apo B-100/apo B-70.5 heterozygotes by sequential ultracentrifugation combined with immunoaffinity chromatography. Cell culture experiments, ligand blot analysis, and in vivo studies all consistently showed that Lp B-70.5 is not recognized by the LDL receptor. The kidney was identified as a major organ in catabolism of Lp B-70.5 in New Zealand white rabbits. Autoradiographic analysis revealed that renal proximal tubular cells selectively removed Lp B-70.5. On ligand blotting of renal cortical membranes, Lp B-70.5 bound only to megalin. The ability of megalin to mediate cellular endocytosis of Lp B-70.5 was confirmed using retinoic acid/dibutyryl cAMP-treated F9 cells. This study suggests that the putative LDL receptor-binding site A on apo B-100 might not by itself be a functional binding domain and that the apo B-binding sites recognized by the LDL receptor and by megalin may be different. Moreover, megalin may play an important role in renal catabolism of apo B truncations, including apo B-70.5.

Effects of breeder age and dietary fat on subsequent broiler performance. 2. Slaughter yield

The effects of breeder age (35, 51, and 63 wk) and added dietary fat on subsequent broiler slaughter yield were evaluated. Beginning at 22 wk of age, diets included 0, 1.5, or 3.0% added poultry fat (PF), 1.5 or 3.0% added corn oil (CO), or 3.0% added lard (LA). Slaughter yields were greatest in broilers from 63-wk-old breeders. Added CO in broiler breeder diets significantly increased subsequent 43-d live BW and chilled carcass yields compared to LA. Furthermore, CO diets significantly increased relative front-half yields compared to PF diets; and compared to the 3.0% fat level, 1.5% added fat significantly increased 43-d live BW, regardless of fat type. In conclusion, breeder age influenced broiler slaughter yield, and fat added at the 1.5% level to breeder hen diets was an effective energy source. However, less saturated fat improved subsequent slaughter yield.

Effects of breeder age and dietary fat on subsequent broiler performance. 1. Growth, mortality, and feed conversion

The effects of breeder age (35, 51, and 63 wk) and added dietary fat on subsequent broiler growth, mortality, and feed conversion through 42 d were evaluated. Beginning at 22 wk of age, diets included 0, 1.5, or 3.0% added poultry fat (PF), 1.5 or 3.0% added corn oil (CO), or 3.0% added lard (LA). Broilers from hens 35 wk of age performed better between 0 and 21 d than those from 51- and 63-wk-old hens. Conversely, between 22 and 42 d, broilers from hens 51 wk of age performed better than those at 35 and 63 wk. In relation to PF, CO added to breeder diets increased 0 to 21 d BW gain in broilers; whereas, feed conversion between 22 and 42 d was reduced in broilers from hens fed PF compared to those fed CO. In conclusion, breeder age influenced broiler performance differently throughout the growout period. Fat added at the 1.5% level to breeder hen diets was an effective energy source. However, less saturated fat improved growout performance.

Effects of alcohol and cholesterol feeding on lipoprotein metabolism and cholesterol absorption in rabbits

Alcohol fed to rabbits in a liquid formula at 30% of calories increased plasma cholesterol by 36% in the absence of dietary cholesterol and by 40% in the presence of a 0.5% cholesterol diet. The increase was caused almost entirely by VLDL, IDL, and LDL. Cholesterol feeding decreased the fractional catabolic rate for VLDL and LDL apoprotein by 80% and 57%, respectively, and increased the production rate of VLDL and LDL apoprotein by 75% and 15%, respectively. Alcohol feeding had no effect on VLDL apoprotein production but increased LDL production rate by 55%. The efficiency of intestinal cholesterol absorption was increased by alcohol. In the presence of dietary cholesterol, percent cholesterol absorption rose from 34.4+/-2.6% to 44.9+/-2.5% and in the absence of dietary cholesterol, from 84.3+/-1.4% to 88.9+/-1.0%. Increased cholesterol absorption and increased LDL production rate may be important mechanisms for exacerbation by alcohol of hypercholesterolemia in the cholesterol-fed rabbit model.

Effects of dietary fat and eggshell cuticle removal on egg water loss and embryo growth in broiler hatching eggs

The effects of dietary fat and eggshell cuticle removal on egg water loss, embryo growth, and hatchability were determined in eggs from broiler breeder hens at different ages. Hens were fed isocaloric diets containing one of three different types and levels of added fat. In addition, eggs were either left intact or washed to remove the eggshell cuticle prior to set. Cuticle removal increased egg water loss between 43 and 62 wk. Cuticle removal increased relative wet embryo weight at Week 52 and relative dry embryo weight at 52 and 62 wk. Furthermore, at 62 wk, diet and day of incubation interacted to affect wet embryo weight, and diet variably affected dry embryo weight. No treatment differences were observed for cumulative hatchability, rate of hatch, and relative yolk sac weight at Day 19 of incubation. It was concluded that cuticle removal and the addition of fat to breeder diets may influence embryonic growth without having any subsequent effects on hatchability.

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.