Biomedical subjects

D R Korver

Publications and source records attributed to D R Korver.

15 recordsLinked to original sources

PubMed2006

Investigating the effects of commercial probiotics on broiler chick quality and production efficiency.

A study was undertaken to test the effect of 2 commercially available probiotics on the production efficiency of broiler chickens hatched from the same breeder flock at 3 different ages (28, 43, and 57 wk). At each of the 3 breeder flock ages, 1,600 broiler chickens were hatched and randomly allocated to 1 of 4 treatments: 1) no probiotics (control), 2) probiotic 1 administered in the drinking water, 3) probiotic 1 administered as a spray, and 4) probiotic 2 administered in the feed. A coccidiostat was included in the feed, but no other antimicrobial agents were given. Broilers were then reared on straw litter in identical floor pens for a period of 6 wk. There were no significant differences in broiler BW, feed conversion, or mortality between the probiotic treatments and the control group in any of the trials. The 43-wk-old breeder flock had the highest fertility and hatchability and the lowest percentage of chicks culled at hatching. Throughout the broiler production period, the broilers from the 43- and 57-wk-old breeder flocks had higher BW and weight gains than the broilers produced at 28 wk of breeder flock age. Broiler feed conversion over the 6-wk production period decreased as the breeder flock aged. Probiotics had no effect on chick quality or production efficiency in broilers produced by the breeder flock ages examined.

Aging↗

PubMed2006

Relationship between bicarbonate retention and bone characteristics in broiler chickens.

Determination of the bicarbonate retention factor (BRF) is an important step during development of the indicator amino acid oxidation technique for use in a new model. A series of 4-h oxidation experiments were performed to determine the BRF of broilers aged 7, 14, 21, 28, 35, and 42 d using 4 birds per age group. A priming dose of 1.2 microCi of NaH(14)CO(3), followed by eight half-hourly doses of 1 microCi of NaH(14)CO(3) were given orally to each of 4 birds per age. The percentage of (14)C dose expired by the bird at a steady state was measured. These birds, as well as 12 additional birds matched for age and BW, were killed, and femur bone mineral density was measured by quantitative computed tomography to determine the relationship between bone development and bicarbonate retention at each age. There was a correlation (r = 0.50; P < 0.05) between total cross-sectional femur bone mineral density and bicarbonate retention at each age. A prediction equation (Y = 6.95 x 10(-2)X - 3.51 x 10(-5)X(2) + 27.58; P < 0.0001, R(2) = 0.79) where Y = bicarbonate retention and X = BW was generated to predict Y as a function of X. Bicarbonate retention values peaked at 28 d, during the stage of the most rapid bone deposition and the highest growth rate. A constant BRF was found from 1,900 to 2,700 g of BW of 35.15 +/- 1.095% (mean +/- SEM). This retention factor will allow the accurate correction of oxidation of (14)C-labeled substrates in broilers of different ages and BW in future indicator amino acid oxidation studies.

Aging↗

PubMed2006

Relationship of dietary antimicrobial drug administration with broiler performance, decreased population levels of Lactobacillus salivarius, and reduced bile salt deconjugation in the ileum of broiler chickens.

Straight-run broiler chickens were raised either in floor pens or wire-floored cages (trial 1) or in floor pens only (trials 2, 3, and 4). Birds raised in floor pens had lower BW and feed intakes than those raised in cages. The administration of bacitracin in the feed increased feed intake from d 12 to d 35, decreased the feed conversion ratio during the same period in trial 2, and improved the weight gain of broilers from d 0 to 10 in trial 3. The concentrations of conjugated bile salts (taurocholic and taurochenodeoxycholic acids) were higher in the ileal contents of broilers administered the antimicrobials compared with untreated birds. Supplementation of the feed with monensin increased fat digestibility in the ileum of the birds. Although total numbers of bacteria in ileal contents were the same regardless of whether antimicrobials were administered or not, the bacterial community differed qualitatively. Populations of Lactobacillus salivarius were reduced in birds fed antimicrobials relative to untreated broilers. A representative ileal isolate of L. salivarius deconjugated bile salts in pure culture in the laboratory and in the ileal contents of ex-Lactobacillus-free chickens maintained in a protective environment and colonized by the Lactobacillus isolate. These observations provide a link between bile salt deconjugation in the ileum by L. salivarius and decreased weight gain of broilers. Lactobacillus salivarius populations could be targeted in future studies aimed at modification of the ileal bacterial community to achieve growth promotion of broilers without the administration of antimicrobial drugs.

Animal Feed↗

PubMed2006

A study on the interaction of xylanase and phytase enzymes in wheat-based diets fed to commercial white and brown egg laying hens.

A trial was conducted to investigate potential interactions between phytase and xylanase enzymes in wheat-based laying diets. Hens (480 ISA-White and 480 ISA-Brown) were distributed into 160 experimental units and fed one of 10 diets containing 75 to 77% wheat from 33 to 64 wk of age with a diet change at 49 wk. Two diets were adequate in P content (0.3 and 0.25% available P in the 2 phases) with or without xylanase (0 or 2,000 U/kg; Avizyme 2300, Danisco Animal Nutrition, Marlborough, Wiltshire, United Kingdom), and 8 diets had reduced P (0.2 and 0.15% available P) with or without xylanase and phytase (0, 300, 500, and 700 ppu/kg; Phyzyme 5000G, Danisco Animal Nutrition). Egg production was higher for ISA-Brown than for ISA-White hens, and ISA-Brown hens were larger. Eggs from ISA-Brown hens had lower albumen height; higher egg, shell, and albumen weights; and lower yolk weight than those from ISA-White hens. Egg production was not affected by the diet. In P-reduced diets without xylanase, phytase significantly increased BW gain in the first period with no change in feed intake or feed efficiency. In P-adequate diets, xylanase increased egg and albumen weight and albumen height. In P-reduced diets with xylanase, increasing levels of phytase increased egg and albumen weight. This trial demonstrated no negative interactions between these enzymes for production traits and no interactions between the diet and strain of hen. These data suggest that poultry producers can use these enzymes individually or together in feed for the Brown and White egg layers used in this study without concern for the strain of hen.

6-Phytase↗

PubMed2006

Effect of strain of layer and age at photostimulation on egg production, egg quality, and bone strength.

Bone strength in layers is a concern for economic reasons and animal welfare concerns. Bone characteristics were investigated in 3 strains of hens: Babcock B-300, a small-bodied commercial white-egg layer; ISA-Brown, a commercial brown-egg layer; and an unselected Brown Leghorn line (BL). After being reared together in a single pen with 8 h of light per day, hens were caged with 14 h of light per day. Half of the hens were caged at 18 wk of age and the other half at 20 wk of age, resulting in a 2-wk difference in the age at photostimulation. Body weights, egg production, feed efficiency, and egg quality were measured throughout production. At 15, 25, 50, and 74 wk of age, hens were euthanized for sampling of the radius and the humerus. Breaking strength of the radius and humerus was measured, and the area and density of trabecular (largely medullary bone) and cortical bone were measured using quantitative computed tomography. Egg production and feed conversion of ISA-Brown hens was as good as or better than that of Babcock B-300 hens, and both commercial strains had higher production than the BL. Photostimulation late delayed sexual maturity and improved albumen and shell characteristics but had only minor effects on egg production and did not affect the yolk weight. The delayed photostimulation resulting from caging 2 wk later affected the radius by increasing the area of the trabecular space at 50 wk of age and the density of the bone in the trabecular space at 74 wk of age. Breaking strength of the humerus at 25 wk of age was greater for the birds that were photostimulated late but was not different later in the trial. The humerus, but not the radius, of the BL had a greater breaking strength than that of the commercial strains, suggesting that selection has decreased humeral breaking strength.

Aging↗

PubMed2004

Assessing bone mineral density in vivo: quantitative computed tomography.

Egg-laying hens require substantial amounts of Ca to support eggshell formation. Over time, structural bone is catabolized to provide some of the Ca required; the structural bone is not replaced. As the hen ages, this can eventually lead to osteoporosis. Quantitative Computed Tomography (QCT) is a nondestructive technique used to measure bone mineral density (BMD). QCT is used diagnostically in humans to assess osteoporosis; BMD determined by QCT is correlated with other, more invasive methods of bone mineral determinations, such as ashing. An x-ray is sent through a bone at multiple angles within a plane to generate a 2-dimensional image and a 3-dimensional calculation of volume and BMD. The technique allows resolution of total, trabecular, and cortical BMD and cross-sectional areas. The separation of bone types allows very precise measurements of the bone compartments most important in Ca supply for eggshell formation and bone strength. QCT has been adapted in our laboratory to measure BMD in vivo and ex vivo in poultry; values obtained for poultry bones are moderately correlated with destructive means of assessing bone quality such as breaking strength, ashing, and chemical bone mineral determinations. Thus, changes in BMD of individual birds can be measured over time; BMD at specific time points can be correlated with production parameters and eggshell quality traits. QCT is an effective technique to measure BMD in laying hens, which allows resolution of total BMD as well as cortical and trabecular BMD.

Aging↗

PubMed2004

End-of-cycle bone quality in white- and brown-egg laying hens.

Broken and weak bones of laying hens are major welfare concerns in the table egg industry. Bone quality at the end of lay of brown- (Shaver 579) and white-(Shaver 2000) egg strains were compared. Prior to the start of the experiment, the hens had been housed in laying hen cages (2/cage). At 423 d of age (60 wk + 3 d), 24 hens of each strain were selected and individually caged, and egg production records were kept until 462 d of age (the end of 65 wk) for a total of 39 d. Egg quality analysis was undertaken during wk 65 of age. Hens were killed at 66 wk of age (463 d), and carcass and reproductive morphology traits were measured. Femur and humerus mineral density were measured using quantitative computed tomography, and breaking strength was measured by an Instron Materials Tester. The white-egg strain produced 3.7% more marketable eggs during the experiment due to a 0.3 d shorter mean pause length in egg production. Eggs from the brown strain were 3.4% heavier, had 4.0% more eggshell, and had a higher specific gravity than the white strain eggs (1.077 and 1.072, respectively). Final BW was 330 g greater in the brown-egg strain. Total bone density of the femur was not different between the 2 strains but was greater in the humerus of the brown-egg layers. Total femur and humerus bone areas were greater in the brown strain than the white-egg strain. Bone breaking strengths of the brown-egg strain were greater by 22% (femur) and 18% (humerus) than in the white-egg strain hens. These results indicate that this brown-egg strain may be more resistant to weak and broken bones at the end of production than the white-egg strain.

Aging↗

PubMed2004

Performance characteristics and economic comparison of broiler chickens fed wheat- and triticale-based diets.

The effects of triticale and wheat on broiler (mixed sexes) performance and cost of production were compared. In experiment 1, wheat- and triticale-based diets were fed to 3 strains of broilers (Ross x Ross, Hubbard x Hubbard, and Ross x Hubbard). Each of the diets was provided to 5 cages/strain (n = 10 chicks/cage; 1,273 cm2/bird). Weekly BW, gain, feed consumption, and feed conversion ratio (FCR; g of feed/g of gain) were determined. At 42 d, 4 chicks/pen were shipped to a commercial processing plant. The plucked, eviscerated carcasses were evaluated for carcass traits. Overall, the triticale-fed birds had lower final BW and average daily gain and higher FCR. Eviscerated carcass, thigh, and drum weights were lower, but pectoralis minor as a percentage of carcass weight was greater in triticale-fed birds. In experiment 2, a wheat diet and a diet in which triticale was substituted (by weight) for wheat were provided in a 3-phase feeding program. Each diet was provided to 2 identically-equipped commercial barns housing 17,034 broilers each. Individual BW of a sample of birds were recorded in each barn at 0, 19, 34, and 42 d, corresponding to the beginning and end of each dietary phase. Feed consumption and FCR were calculated for each barn. An analysis of each of the diets was calculated using a broiler chicken production cost model. Final BW, feed consumption, carcass weight at processing, flock uniformity, percentage of Grade A carcasses, and percentage of condemned carcasses were not affected by cereal source. Overall FCR (2.165, 2.036; P = 0.0052), feed cost (dollars 0.617, dollars 0.577/kg live weight; P = 0.0260), and total cost of production (dollars 1.019, dollars 0.972/kg live weight; P = 0.0183) were greater for the triticale than wheat diets, respectively. Triticale would be an economically feasible replacement for wheat in broiler diets when its price is less than or equal to 95% of the cost of wheat, less dollars 18 (Canadian). Increased knowledge of the available nutrient profile of triticale, as well as least-cost feed formulation would likely increase the value of triticale relative to wheat for broilers.

Animal Nutritional Physiological Phenomena↗

PubMed2004

Effects of nutrient density on growth and carcass traits in fast- and slow-feathering female turkeys.

Chickens have been sexed based on feather development at hatching for many years, but the slow-feathering gene has only recently been incorporated into a commercial line of turkeys. Female turkeys of a fast- and a slow-feathering strain were compared with regard to BW, gain, and carcass composition to 29 wk of age. A total of 432 fast-feathering (FF) and 432 slow-feathering (SF) poults were reared to 198 d on a control (CON) or a high-energy, high-protein (HIGH) diet. Data concerning BW and carcass characteristics (thoracic circumference and width, shank, keel, breast muscle, fat pad, and liver), feather scores, and breast muscle morphology were assessed over the course of the trial. Strain did not affect BW of the CON-fed birds until after 112 d, when FF birds were 3.1% heavier than SF birds. From 11 to 112 d, feeding the HIGH diet increased BW of SF birds significantly compared with birds fed the CON diet. From 170 to 198 d, FF birds were approximately 0.8 kg heavier than SF birds. At 42 and 84 d in FF birds, and at 84 d in SF birds, increased diet density increased measures of frame size and decreased liver weight. Breast muscle weight, area, and thickness were greater in SF than in FF birds at 42 and 84 d. Increased nutrient density increased feather score in SF birds at 32 (9.8%) and 56 d (7.1%).

Animal Feed↗

PubMed2002

Development of the indicator amino acid oxidation technique in chickens: L-[1-(14)C]phenylalanine infusion dose and phenylalanine oxidation.

Amino acid requirements of broiler breeder chickens are not well known. The indicator amino acid oxidation (IAAO) technique was adapted for use in broiler breeders as a rapid and sensitive method to determine amino acid requirements. During IAAO, phenylalanine oxidation decreases, inversely to the changes in protein synthesis, as the intake of the limiting test amino acid increases from deficient to adequate. Above the adequate level, phenylalanine oxidation remains constant. Before IAAO can be employed, the optimum priming and constant infusion doses of phenylalanine must be determined. Prelaying catheterized birds aged 20 to 24 wk were placed in closed oxidation chambers attached to a breath collection apparatus. A constant L-[1-(14)C]phenylalanine dose of 3.5 microCi/kg BW/h and priming doses of 4.5, 5.5, and 7.0 microCi/kg BW were used to determine optimal prime:constant dose ratios, minimum time taken for breath 14CO2 excretion to become constant (plateau), and adequate percentage of phenylalanine oxidized. At this constant infusion rate, the optimal priming dose of L-[1-(14)C]phenylalanine was 5.5 microCi/kg BW, resulting in a prime:constant dose ratio of 1.6:1. By using this ratio, the average time taken for breath 14CO2 to reach plateau was 60 min. Average phenylalanine oxidation at plateau, corrected for bicarbonate retention, was 5.5 +/- 1.4% (mean +/- SD), which is adequate for IAAO studies using deficient-to-excess levels of test amino acids. To the authors' knowledge, this study is the first in chickens to establish a primed, constant infusion technique using L-[1-(14)C]phenylalanine. The IAAO technique will be used in future studies to determine amino acid requirements in chickens.

Animal Nutritional Physiological Phenomena↗

PubMed2002

Development of the indicator amino acid oxidation technique in chickens: calibration of oxidation system and determination of bicarbonate retention factor.

The indicator amino acid oxidation technique has been widely used as a rapid and sensitive method to determine amino acid requirement. In this technique, the indicator 14C-amino acid is continuously infused and breath 14CO2 is collected to determine oxidation rate, which is used to predict requirement. However, a portion of the 14CO2 produced from amino acid oxidation is retained in the body and must be determined to correct oxidation rates based on breath 14CO2 collection. To develop the indicator amino acid oxidation technique for use in poultry, it is important to accurately measure expired and retained CO2; these measurements were accomplished using intravenous infusion of NaH14CO3. Oxidation chambers were constructed and calibrated to ensure complete collection of breath 14CO2. Hydrochloric acid was infused over 1 h into a beaker containing NaH14CO3 in four closed oxidation chambers, and the 14CO2 released was collected over 2 h. Of the initial radioactivity dose, 99.3 +/- 1.9% was recovered in collected 14CO2. We concluded that the oxidation chamber apparatus is adequate for complete recovery of expired 14CO2. In Experiment 2, we determined bicarbonate retention in five broiler breeder roosters from a primed, constant infusion of NaH14CO3 into the jugular vein for 4 h. At steady state, 86.0 +/- 1.4% of NaH14CO3 infusion was recovered in breath. Because 14% of infused 14C is retained within the body, the present results demonstrate the need to determine bicarbonate retention in chickens during oxidation studies and use it as a correction factor in subsequent experiments.

Amino Acids↗

PubMed2000

Effect of dietary protein intake during the pullet-to-breeder transition period on early egg weight and production in broiler breeders.

The effects of CP intake on broiler breeder hen performance were evaluated. A flock of pullets was reared in floor pens from 0 d to 20 wk of age. At 20 wk of age, 96 pullets were randomly assigned to one of three feeding regimens with 14, 16, or 18% dietary CP. Daily feed allocation from 20 to 29 wk of age was identical for all three treatments and was based on the BW of the birds fed the 16% CP diet. Photostimulation occurred at 22 wk of age. At 29 wk of age, the hens were killed for determination of carcass characteristics. Dietary protein intake did not influence BW or BW gain throughout the trial. There were no differences in age at sexual maturity among treatments. From 25 to 28 wk of age, the hens on the 16 and 18% CP treatments had a significantly greater egg weight than did hens in the 14% CP group. The 14% CP treatment was unable to sustain as high a level of egg production as the other two treatments at 29 wk of age. The number of settable eggs was also lowest for the 14% CP treatment. The CP level in the diet did not affect the weights of the Pectoralis major or minor. Carcass composition was also not different among the treatments. Increased levels of CP in the prelay and early lay diets increased egg size and production rate although had minimal effect on carcass and ovarian parameters.

Adipose Tissue↗

PubMed1998

Effect of dietary energy level and oil source on broiler performance and response to an inflammatory challenge.

Broiler chicks were fed one of five diets from 3 d of age: a low energy diet containing 7% cellulose (ME 2,714 kcal/kg), or high energy diets containing approximately 7% of either tallow, corn oil, safflower oil, or fish oil (each 3,302 kcal/kg). Half of the chicks were injected intra-abdominally with Salmonella typhimurium lipopolysaccharide (LPS) on Day 11, sephadex on Day 13, and Freund's complete adjuvant on Day 15; samples were collected on Day 16. The uninjected chicks served as controls. In a second experiment, 3-d-old chicks were fed one of eight isocaloric diets containing tallow as the sole supplemental fat source, or tallow plus either 2% corn oil, 1, 1.5, or 2% fish oil, or fish meal at an amount to provide 1, 1.5 or 2% supplemental oil. Half of the chicks were injected intra-abdominally with S. typhimurium LPS on Days 10, 12 and 14; the uninjected chicks served as controls. Samples were taken on Day 15. In Experiment 1, the cellulose diet decreased performance to 10 d of age relative to the other diets, whereas immunogen injection decreased weight gain and feed efficiency and increased indices of inflammation among all dietary groups. Fish oil at approximately 7% of the diet did not improve weight gain. Fish oil diets improved weight gain and feed efficiency in Experiment 2 relative to the other diets, in spite of minimal effects on indices of inflammation. Injection of LPS decreased performance and increased inflammation across dietary treatment, although the second LPS injection was less potent in altering performance responses and inflammation compared to the first injection, indicating that repeated injections of LPS amy cause the chicks to become refractory to that stimulus. The fish meal diets resulted in poorer performance than similar levels of lipid provided as fish oil. Lower levels of dietary fish oil were more efficacious in improving broiler performance than higher levels, and fish oil provided from fish meal was not as efficacious as oil per se, possibly due to nonlipid components of the meal.

Animals↗

PubMed1997

Dietary fish oil alters specific and inflammatory immune responses in chicks.

Two experiments were designed to determine the effects of dietary (n-3) fatty acids and grain source on the growth-suppressive effects of the inflammatory response and indices of specific immunity. In Experiment 1, chicks were fed diets containing 0.5, 1, or 2 g/100 g of either corn oil or fish oil. In Experiment 2, chicks were fed diets containing up to 2 g/100 g of either fish oil, linseed oil or corn oil as the source of dietary fat, in either cereal grain- or corn-based diets. In each experiment, subsets of chicks within each dietary treatment were either vaccinated with infectious bronchitis virus (IBV) vaccine, injected with Salmonella typhimurium lipopolysaccharide (LPS), heat-killed Staphylococcus aureus, or remained noninjected. Increasing dietary fish oil, but not corn oil increased body weight and lessened the growth-suppressing effect of heat-killed S. aureus or S. typhimurium LPS. Increasing the concentration of dietary fish oil decreased febrile response, circulating hemopexin and metallothionein concentrations. Dietary fish oil resulted in decreased release relative to dietary corn oil of interleukin-1 by peritoneal macrophages. Although IBV titers were not significantly affected by dietary oil treatment, phytohemagglutination-induced wattle swelling was greater among chicks fed fish oil. In Experiment 2, the modulating effects of fish oil on the immune system were dependent on the type of grain used in the diet, with fish oil/cereal diets resulting in greater cell-mediated immunity and lower indices of inflammation than fish oil/corn diets. Inclusion of increasing amounts of fish oil in the diet improved performance, decreased indices of the inflammatory response and either improved or did not change indices of the specific immune response of growing chicks.

Animals↗

PubMed1997

Dietary fish oil or lofrin, a 5-lipoxygenase inhibitor, decrease the growth-suppressing effects of coccidiosis in broiler chicks.

Broiler chicks were fed a diet containing 4% of either corn oil or fish oil from 3 to 14 d of age. From Days 15 to 23, half of the chicks in each dietary treatment were fed Lofrin (an experimental 5-lipoxygenase inhibitor) at 33 micrograms/kg feed. The remaining chicks within each dietary treatment were the untreated controls. At 24 d of age, half of the chicks within each diet-Lofrin treatment group were each infected with 4.6 x 10(4) sporulated Eimeria tenella oocysts, resulting in a 2 x 2 x 2 factorial arrangement of treatments. Body weight gain, feed consumption, and feed conversion efficiency were determined throughout the study. At 27 d of age, blood, liver, and ceca were sampled. Plasma tumor necrosis factor and hemopexin, hepatic fatty acid composition, and cecal inflammatory cell infiltration were determined. Liver fatty acid composition tended to reflect that of the diet. Chicks fed fish oil had livers that were enriched in (n-3) polyunsaturated fatty acids (PUFA) at the expense of (n-6) PUFA. Chicks fed fish oil gained body weight more rapidly than those fed corn oil. Infection of chicks with Eimeria decreased body weight gain of chicks fed corn oil, but not of chicks fed fish oil. The addition of Lofrin to the corn oil diets abrogated the growth-suppressing effects of infection, although there was no Lofrin effect among chicks fed fish oil. There was a diet by Lofrin interaction in which Lofrin treatment of birds fed corn oil decreased feed consumption and increased feed conversion efficiency, but had no effect on chicks fed diets containing fish oil. Plasma hemopexin was greater, but tumor necrosis factor was lower, in chicks fed fish oil than in chicks fed corn oil. Eimeria infection significantly increased cecal inflammatory cell infiltration across all dietary treatments. There were no clear relationships between growth rate or efficiency and the severity of the inflammatory response to Eimeria infection, as indicated by hemopexin levels and cecal inflammatory scores. These results indicate that Lofrin or fish oil, both of which modify eicosanoid metabolism, attenuate the growth-depressing effects of an Eimeria tenella infection.

Aging↗