Biomedical subjects

M S Lilburn

Publications and source records attributed to M S Lilburn.

At least 19 recordsLinked to original sources

PubMed2006

Protein quality of poultry by-product meal manufactured from whole fowl co-extruded with corn or wheat.

Three experiments were conducted with turkey poults to characterize the protein quality of a novel poultry by-product meal composed of aged fowl extruded with either corn (CHM) or wheat (WHM). In Experiment 1, a growth assay was conducted to determine a dietary protein response range for semipurified diets containing CHM or WHM as the sole sources of dietary protein. Diets contained 12, 15, and 18% CP, and there was a linear increase in BW with no significant differences between the 2 sources. The same dietary protein levels were used to determine the protein efficiency ratio (PER), net protein ratio (NPR), and apparent amino acid digestibility of CHM and WHM in Experiments 2 and 3. In Experiment 3, WHM and CHM were also compared with soybean meal (SBM) and meat and bone meal (MBM). In Experiment 2, there were no significant differences between CHM and WHM in PER or NPR, but the variability between levels of CP did account for a significant level of CP x source interaction (P < 0.05). In Experiment 3, there were no significant protein level effects on PER or NPR, but the values for MBM were consistently lower than those for CHM, WHM, and SBM. The apparent amino acid digestibility coefficients for MBM were also consistently lower than those for CHM and WHM. In conclusion, the extruded WHM and CHM products have acceptable protein quality and were better than MBM as single sources of dietary protein.

Animal Feed↗

PubMed2005

Analysis of myosin isoform transitions during growth and development in diverse chicken genotypes.

The temporal expression of chicken skeletal fast myosin heavy chain (MyHC) isoforms in pectoralis major muscle was characterized in 3 commercial broiler lines at embryonic d 19 and at 7, 14, and 21 d posthatch. Lines A and B have been selected for breast yield, and line C is a fast' growing commercial line with limited selection for carcass traits. The isoform transitions in breast muscle samples were compared with samples from Single Comb White Leghorns (line D) using a semiquantitative immunoassay. The hypothesis was that selection for growth and carcass development in broilers would be accompanied by changes in the temporal expression of one or more of the chicken fast MyHC isoforms. Embryos from all lines were sampled at 19 d of incubation, and chicks were randomly sampled at 7, 14, and 21 d post-hatch. Myosin was extracted from pectoralis major muscle and assayed for purity and total protein concentration by SDS-PAGE and bincinchoninic acid protein analyses, respectively. The relative concentration of MyHC isoforms was evaluated by semiquantitative ELISA with 3 monoclonal antibodies specific for chicken skeletal fast embryonic and adult (eMyHC, aMyHC; EB165), neonatal (nMyHC; 2E9), and adult (aMyHC; AB8) myosin, respectively. The overall temporal expression of the myosin isoforms, eMyHC, nMyHC, and aMyHC, was similar in all lines. With eMyHC, at 19 d of incubation, line B had lower expression than lines A, C, and D. Expression of nMyHC, in lines C and D was similar with expression being highest at 7 d and lower at 14 d and 21 d. In lines A and B, however, nMyHC expression was higher at hatch than lines C and D. In line D, aMyHC was expressed at 14 d and increased through 21 d, whereas in lines A, B, and C, aMyHC isoform was expressed and was higher at 7 d and increased through 21 d. The results of this experiment support our hypothesis that commercial broilers have different temporal expression patterns of the developmental chicken fast MyHC isoforms.

Aging↗

PubMed2005

Comparative development of the small intestine in the turkey poult and Pekin duckling.

Turkey poults and Pekin ducklings hatch from eggs of similar weights and have the same incubation periods and body weights at hatch. The male Pekin duckling, however, can attain a market weight of 3.2 kg in approximately 6 wk, whereas at the same age, male turkeys only weigh approximately 2.1 kg. For this study, fertile turkey eggs (n = 400, mean weight: 87.2 g, range: 85 to 89.9 g) and Pekin duck eggs (n = 565, mean weight: 88.6 g, range: 85 to 92.0 g) were weighed and incubated. Embryos and hatchlings were sampled during the last week of incubation, at hatch, and through 7 d of age. Yolk-free BW of poults were 2.7 g heavier than ducklings at hatch. Yolk-free BW of ducklings, however, were greater than poults at 1 d of age (P > or = 0.06), and by 7 d of age ducklings were 140 g heavier (P < or = 0.01). Yolk sac weight was similar at 21 and 25 d of incubation, yet was significantly lower in ducks at hatch, 1, and 2 d of age (P < or = 0.05). In the duckling, jejunum and ileum weights (3.7x heavier), length (1.6x longer), and density (g/cm; 2.3x more dense) were consistently heavier than in the turkey from hatch through 7 d (P < or = 0.01). Histological sections of the distal jejunum revealed more rapid villus growth in the duck from 0 to 3 d of age. The combination of increased intestinal growth (weight and length) and maturation (villus length) allowed ducks to achieve an additional 143 g of BW gain during the critical hatch through 7 d of growth.

Aging↗

PubMed2004

Preovulatory surge patterns of luteinizing hormone, progesterone, and estradiol-17beta in broiler breeder hens fed ad libitum or restricted fed.

Spontaneous ovulations are induced by preovulatory surges of luteinizing hormone (LH) and progesterone (P4) during ovulatory cycles in birds, but estradiol-17beta (E2) levels are relatively constant. Egg production is enhanced in restricted fed (RF) in comparison with ad libitum fed (FF) broiler breeder hens, but changes in concentrations and peripheral patterns of LH, P4, and E2 during ovulatory cycles in broiler breeder hens are poorly documented. The hypothesis of this study was that high resolution patterns of peripheral LH, P4, and E2 during preovulatory surges would not be different between FF and RF broiler breeder hens. Seven FF and 6 RF broiler breeder hens were photostimulated with 16 L:8 D at 22 wk of age. At 28 wk of age, the hens were cannulated for serial blood sampling and switched to a 24L:0D photoperiod to allow preovulatory surges of LH and P4 to run freely. Three days after cannulation, hens were serially bled every 12 min for 36 h. The FF hens were heavier than the RF hens (5.60 +/- 0.35 vs. 3.60 +/- 0.28 kg, respectively; P < 0.01). During the 10 d before cannulation, total egg production of the FF and RF hens (8.3 +/- 1.4 and 6.8 +/- 1.3 eggs, respectively; P = 0.08) and normal egg production (5.6 +/- 1.8 and 6.5 +/- 1.8 eggs, respectively; P = 0.37) were not different. The FF hens, however, had more abnormal eggs than the RF hens (2.7 +/- 1.7 and 0.3 +/- 0.8 eggs, respectively; P < 0.01). None of the hormonal measurements was different between the FF and RF hens (P > 0.05). The concentrations of hormones for the FF and RF hens, respectively, were as follows: baseline LH (2.79 +/- 0.45 vs. 2.94 +/- 0.60 ng/mL) and P4 (1.68 +/- 0.56 vs. 1.41 +/- 0.43 ng/mL), overall mean LH (3.18 +/- 0.45 vs. 3.10 +/- 0.46 ng/mL) and P4 (2.32 +/- 0.55 vs. 2.09 +/- 0.91 ng/ mL), preovulatory surge amplitude of LH (5.43 +/- 1.27 vs. 3.88 +/- 1.24 ng/mL) and P4 (6.08 +/- 2.09 vs. 6.71 +/- 3.91 ng/ mL), preovulatory surge duration of LH (7.52 +/- 1.80 vs. 5.74 +/- 3.18 h) and P4 (7.52 +/- 1.42 vs. 8.20 +/- 1.24 h), and overall mean E2 (0.25 +/- 0.05 vs. 0.23 +/- 0.05 ng/mL). In conclusion, there were no differences in total egg production or normal egg production between FF and RF broiler breeder hens, but the FF hens laid more abnormal eggs. Also, there were no differences in the concentrations or peripheral patterns of LH, P4, and E2 during preovulatory surges between the FF and RF broiler breeder hens.

Animals↗

PubMed2004

A comparison of growth and development patterns in diverse genotypes of broilers. 1. Male broiler growth.

Selection for breast muscle yield and BW in commercial broilers has resulted in genotypes far different from broilers processed in the past. When comparative studies with commercial lines are conducted, it is often difficult to differentiate between carcass effects resulting from direct genetic selection vs. correlated effects that partially reflect genetic changes in BW. The objective of the present experiment was to compare growth and development characteristics of male broilers from commercial lines exhibiting similar rates of BW gain based on a percentage of 8-wk BW but exhibiting different carcass traits. Male broilers from 2 commercial genotypes exhibiting increased breast muscle yield (A and B) were compared with broilers from a commercial line that was "unimproved" with respect to conformation (C). All birds were fed a commercial-type broiler starter diet throughout the study and were processed at 8 wk of age for carcass comparisons. No differences were observed among lines for breast-free BW or weight of the abdominal fat pad. The absolute and relative weights of pectoralis major and pectoralis minor breast muscles were heavier in lines A and B than C (P < 0.001). Length (C > A > B; P < 0.001), width (B > C >A; P < 0.001), and depth (A = B > C; P < 0.001) of the pectoralis major were different between lines. Drum and thigh weights were heavier in lines A and B than C (P < 0.001). There were genotype differences in tibia length (C > A = B, P < 0.001) and femur length (C > A = B, P < 0.001). The comparison of line C with selected lines A and B, suggested that line C may provide a useful model for studying carcass development between commercial genotypes with similar growth patterns.

Animals↗

PubMed2004

A comparison of growth and development patterns in diverse genotypes of broilers. 2. Pullet growth.

Genetic selection within commercial broiler lines continues to generate improvements in BW, feed conversion, and breast meat yield. The objective of the current experiment was to compare carcass and reproductive characteristics of broiler breeder pullets from 2 dam lines that produce heavy broilers with increased breast yield (A and B) with pullets from a commercial line that does not have the extremes in breast yield (C). Restricted-fed BW were similar at all ages of the experiment in the 3 genotypes. All pullets were photostimulated at 23 wk of age, and carcass and reproductive tract measurements were made at 27 wk of age. There were no differences in BW among the lines at 27 wk of age, but the weights of the pectoralis major and minor breast muscles were heavier in lines A and B compared with line C (P < 0.001). The weight of the abdominal fad pad, however, was heavier in line C (P < 0.04). There was no difference in total drum weight or total thigh weight among lines A, B, or C. Tibia length and tibia width were similar in lines A and C, and the measurements were larger in these lines than in line B (P < 0.02). Femur length was longer (P < 0.001) in line C than in lines A and B, whereas femur width was greater in line C than in line A (P < 0.001) but similar to line B (P < 0.001). Oviduct weight was greater in line C compared with lines A and B (P < 0.004), but there were no differences in total ovarian weight, follicle number, or follicle weight. The information gathered in the present experiment suggested that line C may prove to be useful for reproductive comparisons with commercial lines exhibiting significant differences in carcass traits.

Abdomen↗

PubMed2003

Biochemical analyses of muscles from poultry bred for rapid growth.

In the current study, commercial broiler breeder hens were mated with either commercial broiler breeder males (B/B) or artificially inseminated with semen from Leghorn cockerels (B/L). Embryos and chicks from each mating were used to study the effects of paternal genotype on breast muscle myosin expression without the confounding effects of differences in egg size and embryo development due to maternal genotype. Specifically, the temporal transitions of myosin heavy chain (MyHC) isoforms within the pectoralis (P.) major and P. minor were measured. The relative concentration of the embryonic MyHC isoform increased from d 17 through 21 in ovo in both genotypes and was higher in B/B embryos than in B/L embryos (P < or = 0.01). At 21 d posthatch, there was an increased proportion of the adult MyHC isoform within the P. major and P. minor in B/B compared with B/L chicks (P < or = 0.01). This result suggests that the B/B chicks were making the transition to mature skeletal muscle more rapidly than the B/L chicks. Although samples taken from the P. minor of B/B and B/ L chicks exhibited an increased proportion of the adult MyHC isoform and lower proportion of the neonatal MyHC isoform at 21 d, the genetic differences were far more pronounced in the larger P. major (P < or = 0.01). In summary, the P. major from the faster growing B/B chicks exhibited earlier temporal transitions of developmental fast MyHC, and these differences were evident as early as 17 d in ovo.

Aging↗

PubMed2003

Effect of selection for growth on onset of sexual maturity in randombred and growth-selected lines of Japanese quail.

An experiment was conducted to determine the effect of selection for growth (BW) on the onset of reproduction (first egg) in Japanese quail hens from growth-selected (HW) and randombred (R1) lines. The HW line had undergone over 40 generations of selection for increased 4-wk BW and was originally developed from the R1 line. Data were collected over two consecutive hatches and summarized by hatch and within lines. Body weight at 35 d of age was positively correlated with BW at sexual maturity (first egg) in both the R1 and HW lines, but these correlations were not significant in both hatches for either line (Hatch 1-R1; Hatch 2-HW; P < or = 0.05). There was a negative correlation between age at sexual maturity (days to first egg) and 35 d BW in both lines with the exception of the HW hens in Hatch 2. Age at sexual maturity and BW at sexual maturity was positively correlated (P < or = 0.001) in the R1 line but did not show the same relationship in the HW line. Age at sexual maturity and weight of the abdominal fat pad were positively correlated in the R1 line (Hatch 1, P < or = 0.01; Hatch 2, P < or = 0.001), but this relationship was not significant in the HW line. Age at sexual maturity and follicle number was negatively correlated in both lines but was not significant in Hatch 2 of the HW line. Follicle size, however, was positively correlated with days to first egg in only Hatch 2 (P < or = 0.001) of the HW line. The data suggest that the relationships between the onset of sexual maturity and both reproductive parameters and carcass traits in hens from consecutive hatches of HW quail are less clear than in the R1 line.

Aging↗

PubMed2002

The effect of enzyme predigestion on the nutritional quality of prepressed turkey feather meal.

Three experiments were conducted to determine the protein efficiency ratio (PER), pepsin digestibility, TMEn, and true amino acid availability (TAAA) of prepressed turkey feather meal (PFM), enzyme-digested PFM (EPFM), and commercial feather meal (CFM). Turkey feathers from a commercial processing plant were mechanically pressed alone or mechanically pressed, followed by treatment with a mixture of protease, lipase, and amylase prior to autoclaving. In the first study, feather meal diets containing 16,20, or 24% CP from PFM, EPFM, or CFM were fed to starter poults for 10 d. All diets resulted in negative or negligible growth. In a second study, PFM, EPFM, and CFM were again the primary sources of CP, but dietary protein levels were increased to 20, 24, and 28% CP, and all diets contained 20% corn and 10% soybean meal (PFMCS, EPFMCS, CFMCS), respectively, to allow for a basal level of growth. Performance and PER of the poults fed the diets with PFMCS, EPFMCS, and CFMCS were similar. The efficiency of use of the PFMCS diet was numerically lower (P < or = 0.1) when compared with the EPFMCS and CFMCS diets. Similarly, pepsin digestibilities of EPFM and CFM were higher than PFM. The TAAA of PFM (82.1%) and EPFM (80.6%) were not significantly higher than that of CFM (71.4%); however, the availabilities of lysine, threonine, aspartate, glutamate, proline, and histidine were significantly higher. Digestion of pressed turkey feathers with an enzyme mixture prior to autoclaving could have a positive impact on its protein and amino acid nutritional values.

Amylases↗

PubMed2002

The development of an immunoblotting assay for the quantification of liver fatty acid-binding protein during embryonic and early posthatch development of turkeys (Meleagridis gallopavo).

Turkey (Meleagridis gallopavo) liver cytosolic fatty acid binding protein (FABP) was purified and used as a standard for quantification. An immunoblotting procedure was developed to study the ontogeny of liver cytosolic FABP during embryonic and early posthatch development in turkey poults. Liver FABP activity was also determined indirectly through the use of gel filtration chromatography followed by a ligand-binding assay. The specific activity of liver FABP (ng/mg of cytosolic protein) increased with length of incubation, peaking initially at Day 22, declining between Days 22 and 25, and increasing again from hatch (Day 28) to 6 d posthatch. The specific activity of liver FABP increased 12-fold between Day 13 of incubation and 6 d posthatch compared with total activity, which increased from 946 to 1.01 x 10(6) ng/liver during the same period, a 1,067-fold increase. The results from both analytical procedures were similar, suggesting that the immunoblot method could be used to quantify liver FABP concentrations. The observed increases in FABP activity throughout the embryonic period and first days after hatching paralleled increases in liver lipid concentration. Therefore, liver FABP may be associated with hepatocyte fatty acid transport and metabolism during the latter stages of incubation and early posthatch period.

Animals↗

PubMed2002

The ontogeny of fatty acid-binding protein in turkey (Meleagridis gallopavo) intestine and yolk sac membrane during embryonic and early posthatch development.

Experiments were conducted to confirm the existence and ontogeny of fatty acid binding protein (FABP) in the intestine and yolk sac membrane of turkey poults (Meleagridis gallopavo) during embryonic and early posthatch development. Intestinal (I-) FABP was measured using an immunoblot procedure incorporating anti-chick liver (L-)FABP antisera. FABP activity in both tissues was also confirmed with a ligand-binding assay incorporating 14C-oleic acid. I-FABP did not cross-react with chick L-FABP antisera until hatch, embryonic day 28 (ED 28), after which there was a 39% increase in I-FABP concentration through the first 3 d posthatch (PD 3). FABP concentration calculated on a total intestinal basis (ng/intestine), however, increased 10-fold through PD 6. Specific activity [disintegrations per minute (dpm)/ mg cytosolic protein] was greatest at hatch and decreased slightly thereafter, whereas specific activity of FABP in the yolk sac membrane peaked between ED 16 and ED 19 and then declined. Total yolk sac activity (dpm/yolk sac membrane), however, plateaued at ED 22 before declining to low levels by PD 3, coincident with the period of maximal lipid transfer out of the yolk.

Aging↗

PubMed2002

Growth of the femur and tibia of a commercial broiler line.

The objective of this experiment was to characterize the relationship between growth and skeletal development in commercial broilers as a function of both age and BW. From hatch through 43 d, birds were randomly selected weekly from the same commercial flock for measuring BW, tibia, and femur characteristics. Final BW was 1.8 kg for females and 2.1 kg for males. The fat-extracted weight of the tibia and femur increased proportionately with BW through 43 d of age. Length and width measures as a proportion of their final values at 43 d increased more rapidly than relative changes in BW. The length of the femur as a function of BW reached a plateau at 1.5 kg (35 d of age), whereas the length of the tibia did not plateau through 43 d of age. Differences in width measures between the two long bones were not apparent as BW increased through 43 d of age. The ash percentage of the diaphyseal region (mid-10% of bone) was consistently greater in the tibia than the femur from 15 to 43 d (P < or = 0.05). Differences in mineralization rates and growth characteristics suggest that the functionality and integrity of the femur should not be assumed solely from tibia measurements.

Aging↗

PubMed2000

The developmental expression of acyl-coenzyme A:cholesterol acyltransferase in the yolk sac membrane, liver, and intestine of developing embryos and posthatch turkeys.

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) catalyzes the formation of cholesterol esters (CE) from free cholesterol and fatty acyl-coenzyme A. This experiment was conducted to study the ontogeny of ACAT activity in the yolk sac membrane, liver, and intestine during embryonic development and early posthatch growth of turkeys. The ACAT activity was measured on tissue samples collected at 3-d intervals from embryonic Day (ED 13) 13 through 6 d posthatch (PD 6). The ACAT activity (pmol/mg microsomal protein per min) in the yolk sac membrane increased form 840 pmol at ED 13 to 2,497 pmol at ED 22, and subsequently declined to a very low level by PD 3. The high level of enzyme activity at ED 22 is concomitant with the large quantity of CE formed within the yolk sac membrane at this developmental age. Liver ACAT activity increased from 60 pmol at ED 13 to 242 to 243 pmol at ED 25 and PD 3, followed by a decline to 130 pmol by PD 6, mirroring the peak in hepatic CE concentration. This suggests that even during incubation, the liver plays a significant role in lipid metabolism. Intestinal ACAT specific activity increased from 14 pmol (ED 16) to 44 pmol (ED 25), and then declined to 23 pmol by hatch (ED 28), with no further decline through PD 6. Total intestinal ACAT activity (pmol per intestine/min) increased, however, from ED 16 through PD 6. This increase in activity suggests that the total capacity for cholesterol esterification increases during the course of incubation and shortly after hatching.

Aging↗

PubMed1999

Effect of turkey (Meleagridis gallopavo) breeder hen age and egg size on poult development. 1. Intestinal growth and glucose tolerance of the turkey poult.

Three experiments were conducted to determine if turkey (Meleagridis gallopavo) hen age and egg weight affect poult intestinal development and glucose tolerance during the first week after hatching. Differences in glucose tolerance were not consistent across the experiments. In experiment 1, 4-day-old poults from the younger hens and lightest egg weight class had significantly greater fasting plasma glucose concentrations (P < 0.04) and were also higher at 30 and 60 min post-injection of 250 mg glucose. In experiment 2, egg weight class had no significant effects on plasma glucose concentrations of 4-day-old poults (after injection of 2.5 mg glucose/g body weight). In experiment 3, plasma glucose concentrations were not different between groups at 0 or 30 min post-injection (3.75 mg glucose/g body weight), however, poults from the younger hens had 79-90 mg/dl higher plasma glucose concentrations 60 min post-injection versus poults from the older hens. Neither egg weight class or hen age consistently affected small intestinal weight, length, or density (g/cm) measures across experiments.

Animals↗

PubMed1999

Effect of turkey (Meleagridis gallopavo) breeder hen age and egg size on poult development. 2. Intestinal villus growth, enterocyte migration and proliferation of the turkey poult.

Villus growth, enterocyte migration and proliferation were measured in the small intestine of poults (Meleagridis gallopavo) to determine if hen age and/or egg size influences these characteristics during the first week after hatching. At hatching, distal jejunal villi were 22.8 microns longer in poults from the older (48 weeks) versus the younger (34 weeks) hens (P < 0.05). Similarly, labeled enterocytes in distal jejunal sections from poults from the older hens had migrated 28 microns (10%) farther along the crypt-villus axis at hatching, as compared to poults from the younger hens (P < 0.05). Villus growth differences and enterocyte migration were not consistently affected by hen age or egg weight class in poults from 1 to 7 days old. These results suggest that even though intestinal villi may be more advanced developmentally at hatch in poults from the older hens, however post-hatch growth of the intestine or the poult is not affected by hen age or egg weight class.

Animals↗

PubMed1999

Effects of dietary protein on restrict-fed broiler breeder pullets during a coccidial challenge.

In each of two experiments with young, feed-restricted broiler breeder pullets, the effects of differences in dietary protein intake on intestinal development and growth were studied. All pullets were restrict-fed either a 15 or 19% CP diet to see whether differences in dietary protein would influence intestinal growth in the face of controlled exposure to coccidiosis. In each experiment, pullets were vaccinated with one of three dilutions of Coccivac (control, 1X, 4X), each level representing a different proportion of the manufacturers' suggested dosage level. Experiment 1 was conducted in battery cages with wire floors, and no infection was established, most likely because of a lack of oocyst recycling. The pullets that were restrict-fed the 19% CP diet had a significantly heavier Pectoralis major breast muscle weight at 14 and 21 d postvaccination (PV) and heavier BW at 21 d PV. Experiment 2 was conducted in floor pens with litter. In this experiment, coccidiosis was successfully established as coccidial oocysts invaded the mucosal cells of the villi in the upper small intestine. Pullets fed the 19% CP diet had significantly heavier BW at 14, 28, and 35 d of age. There were, however, no significant effects caused by level of dietary protein or vaccination dose on intestinal development (villus height and crypt depth). In conclusion, mild coccidial infections induced via the administration of commercial anticoccidial vaccines do not warrant changes in dietary protein during the onset of feed restriction in young broiler breeder pullets.

Animals↗

PubMed1999

Effect of hen age on intestinal development and glucose tolerance of the Pekin duckling.

Two experiments were conducted to determine whether hen age affects intestinal development and glucose clearance in Pekin ducklings after hatching. In Experiment 1, 85- to 92-g eggs were collected from 32- and 44-wk-old hens. The eggs from older hens contained proportionately more yolk, which resulted in a greater mass transfer of yolk sac DM and lipid from 21 to 25 d of incubation, and ducklings from older hens were heavier at hatching (P < or = 0.0001). Although the ducklings from the older hens were heavier at hatch, BW, feed consumption, and feed efficiency were not significantly different from 7 to 35 d of age. During the first wk after hatching, the age of the hen had no consistent effect on duodenum or lower small intestinal measurements (weight, length, or density). Hen age did not significantly affect plasma glucose concentrations at 0, 30, or 60 min post-injection of glucose (2.5 mg per g BW) in 3- or 6-d-old feed-deprived ducklings. In a second experiment, 85- to 90-g eggs were collected from 33- and 48-wk-old hens to determine whether differences in hen age caused a differential response to a challenge with a higher glucose dosage at 3 d of age. No differences between hen ages were apparent in plasma glucose concentrations at 0 or 30 min postinjection (3.75 mg glucose/g BW). At 60 min postinjection, however, the ducklings from the younger hens had 100.6 mg/dL greater plasma glucose concentrations than the ducklings from the older hens (P < or = 0.02). The glucose tolerance results suggest that differences in metabolism exist between ducklings from the younger hens, even though measurable BW differences did not exist.

Aging↗

PubMed1999

Effects of feeding high carbohydrate or high fat diets. 1. Growth and metabolic status of the posthatch poult following immediate or delayed access to feed.

Three experiments were conducted with turkey poults to determine the effects of diet and delayed placement on growth and selected aspects of carbohydrate metabolism. Immediately after hatch, poults were placed in batteries and allowed either immediate access to feed and water (FED) or feed and water withdrawal for 48 h (WH). In the first two experiments, diets contained a high proportion of carbohydrate from corn (CHO; 60% of diet) or a lower proportion of corn (26%) and 10% supplemental animal-vegetable fat (FAT). The WH poults weighed less than FED poults at 5 d postfeeding (DPF; P < or = 0.05) but not at 13 DPF. Similarly, poults fed the CHO diet were heavier 5 DPF, whereas poults fed the FAT diet were heavier at 13 DPF (P < or = 0.05). Regardless of feeding regimen (WH vs FED), all poults were nearly depleted of hepatic glycogen prior to feeding. At 2 DPF, poults fed the CHO diet had more hepatic glycogen concentrations compared with those fed the FAT diet (P < or = 0.002). In addition, one-half of the WH poults fed the CHO diet had plasma glucose concentrations in excess of 500 mg/dL at 2 DPF. In Experiment 3, similar feeding regimens and diets were used with the addition of a third diet containing a synthetic medium-chain triglyceride emulsion (MCT) as the supplemental fat source. Poults fed the FAT and MCT diets were 41 g heavier than poults fed the CHO diet at 13 DPF (P < or = 0.05). Similar to the results of Experiment 2, poults fed the CHO diet had increased hepatic glycogen concentrations at 2 DPF, and within the WH treatment at 2 DPF, 30% of the poults had plasma glucose concentrations in excess of 500 mg/dL. Metabolic consequences of delayed placement were also found. At both 4 and 7 DPF, WH poults had a reduced capacity for glucose clearance 60 min after a glucose load (250 mg; P < or = 0.05). The current experiments demonstrate that supplemental fat may ease the metabolic shift toward glycolysis after hatching, thereby improving growth through 2 wk of age.

Animal Feed↗