Biomedical subjects

R D Miles

Publications and source records attributed to R D Miles.

At least 37 records · Page 2Linked to original sources

PubMed1992

Subclinical infectious bursal disease in an integrated broiler production operation.

A field study was designed to determine the prevalence of subclinical infectious bursal disease (IBD) in broiler chickens from a commercial poultry company. Bursae of Fabricius (BF) from two vaccinated and three nonvaccinated broiler flocks were evaluated histologically, and antibody profiles of these broiler and matched parent breeder flocks were established. Lesions of IBD, including lymphoid necrosis, stromal edema, and infiltrates of heterophils and macrophages, were first detected in BF at 24 days of age in both vaccinated and nonvaccinated chickens. At 41 days, all BF had lesions characteristic of IBD, including severe lymphoid depletion, proliferation of epithelial cells, and mild fibroplasia. Although mean maternal antibody levels (measured by enzyme-linked immunosorbent assay) in broilers were apparently protective through day 12, IBD antibodies decreased to nonprotective levels (below 1,000) by day 16 or 20. Titers began to increase by day 28 or 32 because of field exposure. Sentinel birds, placed with broiler flocks, also developed IBD antibody titers. Broiler breeders had low and nonuniform antibody titers. Prevalence of field IBD exposure was high, and existing vaccination programs were not effective.

Animals↗

PubMed1991

Effect of time and sex on tissue selenium concentrations in chicks fed practical diets supplemented with sodium selenite or calcium selenite.

An experiment was conducted with 384 1-d-old male and female broiler-chicks. The basal corn-soybean meal diet (.07 ppm Se DM basis) was supplemented with 0, .1, .2, or .3 ppm added Se as either sodium selenite (Na2SeO3) or calcium selenite (CaSeO3), and fed for 1, 3, or 5 wk. There was no effect of Se source or level on feed intake or gain, but males consumed more (P less than .01) feed than females. There was no effect (P greater than .10) of sex or Se source on plasma, liver, or kidney Se concentration. The Se concentration of all tissues increased (P less than .01) with time and increasing dietary Se concentration. Based on multiple regression slope ratios of liver, kidney, and plasma Se concentrations, Se from CaSeO3 was as available (103%) as Se from Na2SeO3.

Aging↗

PubMed1991

Estimation of the relative bioavailability of inorganic copper sources for chicks using tissue uptake of copper.

An experiment was conducted with 208 day-old male Cobb feather-sexed chicks to study tissue accumulation of Cu as an estimate of biological availability of inorganic Cu sources for chicks. Chicks were allotted randomly to dietary treatments that included an unsupplemented basal corn-soybean meal diet (11.1 mg/kg Cu, DM basis) or this basal diet supplemented with 150, 300 or 450 mg/kg Cu either as reagent-grade acetate or feed grade oxide, carbonate or sulfate. Chicks were housed in batteries and allowed ad libitum access to feed and tap water for 21 d. Liver Cu was not affected by dietary Cu from the oxide source, but it increased (P less than .001) with increasing dietary Cu from all other sources. Bone Cu was lower (P less than .05) in chicks fed 150 mg/kg Cu compared to other dietary levels of Cu but was not influenced (P greater than .10) by Cu source. Using the slope-ratio technique from regression of log liver Cu on mean daily Cu intake with Cu from acetate set at 100%, the relative biological availability values were estimated to be 88.5 and 54.3% for sulfate and carbonate, respectively, and oxide was essentially unavailable.

Animals↗

PubMed1991

Response of broiler breeder females to feed restriction below recommended levels. 1. Growth and reproductive performance.

Arbor Acre broiler breeders were used to determine the effects on growth and reproductive performance of quantitative feed restriction below breeder recommended levels. Feed treatments were: 8% above standard (+8%); standard feeding program (STD); and 8 (-8%), 16 (-16%), and 24% (-24%) below standard. Proportional decreases in feed allocation resulted in corresponding decreases in body weight, frequency of double-yolked eggs, and number of days in production. Egg weight, fertility, hatchability, and female mortality to 64 wk of age were not significantly (P greater than or equal to .05) affected by the reduction in feed intake. Shell quality was significantly improved with the -16 and -24% feed treatments. A delay in sexual maturity caused a significant (P less than or equal to .05) decrease in average rate of lay (%hen-day) but not in total settable eggs for treatments -16 and -24% to 64 wk of age.

Animals↗

PubMed1990

Conditions necessary for a response by the commercial laying hen to supplemental choline and sulfate.

An experiment was conducted with commercial laying hens, 24 wk of age, to study the response from adding 440 mg of choline and sulfate as 2 g of K2SO4 per kg of a corn soybean-meal diet containing different levels of supplemental DL-Met. The basal diet was formulated to be deficient (.495%) in sulfur amino acids, and nonsulfate forms of trace minerals were used in all diets. The experiment was conducted for 22 wk; however, only the data from the last 12 wk were used as the measurement of response since the responses were greatest during this period. Egg production, egg weight, and feed efficiency were improved with each addition of Met from 0 to .2%. Choline supplementation of the diet containing added .033% Met significantly increased egg production. However, no response was obtained from choline supplementation of diets containing 0 or .067% added Met. Addition of sulfate improved egg production when it was added to the diet with choline but not when it was added to the diet with Met.

Animal Feed↗

PubMed1990

Influence of synthetic sodium aluminosilicate on laying hens fed different phosphorus levels.

Two 28-day experiments were conducted utilizing 360 and 180 Leghorn-type hens, 60 and 40 wk of age in Experiments 1 and 2, respectively. In both experiments, a corn-soybean meal basal diet containing no supplemental P was formulated. Dicalcium phosphate was added to the basal diet to supply 0, .05, and .13% supplemental P in Experiment 1 and 0, .13, and .35% supplemental P in Experiment 2. In both experiments, diets were fed with 0 and .75% synthetic sodium aluminosilicate (SAS). The basal diet was calculated to contain .30% P. In Experiment 1, egg production was significantly increased by the addition of .13% supplemental P. When SAS was added to each diet, a decline in egg production and feed consumption was observed. Egg specific gravity increased and egg weight decreased in the presence of SAS. In Experiment 2, egg production was significantly depressed by SAS in the absence of supplemental P and returned to normal with supplemental P. Feed consumption was significantly depressed by adding SAS to diets containing 0 to .13% supplemental P but not to diets containing .35% supplemental P. Egg weight decreased and specific gravity increased when SAS was supplemented to the diet. Data from these two experiments indicate that adequate P intake is advised when using SAS because feed consumption, egg production, and egg weight were decreased in the presence of SAS.

Aluminum Silicates↗

PubMed1990

Influence of aluminum on phosphorus availability in laying hen diets.

An experiment was conducted to determine the influence of Al on P utilization, as well as to determine the short-term response of laying hens to diets containing different levels of P not bound by A1 (PNB). One hundred and sixty Single Comb White Leghorn hens were assigned to eight treatment diets derived from a 2 by 4 factorial design. Diets varying in two percentages of total P (.5 and 1.0%) and four percentages of Al supplementation (.6, .4, .2, and 0%) from aluminum acetate were fed for 15 days. The calculated PNB for the eight treatments were .03, .18, .33, .48, .53, .68, .83, and .98%, respectively. Egg production and feed intake were significantly lower at the two lowest percentages of PNB (.03 and .18%). At the lowest PNB level (.03%), no eggs were laid during the last 2 days of the experiment by any of the 20 hens fed this diet. Plasma inorganic P was significantly decreased by either lowering the total P of the diet or by increasing the Al. These detrimental effects of Al supplementation were completely reversed by increasing the level of P in the diet. Therefore, the detrimental effects of Al are not due to Al per se, but rather are due indirectly through diminishing P availability. Decreased egg specific gravity caused by high percentages of P was reversed by Al supplementation. As the amount of PNB increased, feed consumption also increased. Maximum feed efficiency and egg production were achieved with PNB values between .33 and .98%.

Aluminum↗

PubMed1989

Relative bioavailability of manganese in a manganese-methionine complex for broiler chicks.

The relative bioavailability of Mn from reagent grade Mn monoxide and feed grade Mn-methionine was compared with that from reagent grade Mn sulfate using 288 one-day-old male Cobb chicks. The basal corn-soybean meal diet (93 ppm Mn dry matter basis) was supplemented with 0, 700, 1,400, and 2,100 ppm Mn as Mn sulfate monohydrate, Mn oxide, or Mn-methionine. Additional diets contained 700, 1,400, and 2,100 ppm Mn as sulfate or oxide in combination with .16, .32, or .48% added DL-methionine, respectively, to equalize methionine concentrations in Mn-methionine-containing diets. Diets were fed ad libitum for 3 wk. Tibia and kidney Mn concentrations increased linearly (P less than .001) as dietary Mn increased. Addition of methionine to diets containing sulfate and oxide did not influence (P greater than .10) tissue Mn concentrations. Based on slope ratios from multiple linear regression of bone and kidney Mn concentrations on added dietary Mn from various sources, the respective relative bioavailability values were 96 and 86% from Mn oxide and 108 and 132% from Mn-methionine compared with 100% from Mn sulfate. Except for the first, all values were significantly different from 100%. Thus, Mn from Mn oxide is significantly less available and Mn from Mn-methionine is significantly more available than that from Mn sulfate monohydrate.

Animals↗

PubMed1989

Short-term high level zinc feeding and tissue zinc concentration in mature laying hens.

Two trials were conducted to study the effects of high dietary Zn on tissue Zn accumulation and depletion in laying hens. Hens laying at approximately 60 to 70% were fed a diet containing 20 g Zn as ZnO/kg diet (as fed) for 4 days. For the remaining 18 days, hens were fed the same diet without the 20 g added Zn/kg diet. Ten hens were killed at initiation of the experiment (Day 0), and liver, kidney, and pancreas were obtained for Zn analysis. On Days 1, 2, 3, 4, 10, 16, and 22, similar samples were obtained from 10 hens. Feeding high Zn for 4 days caused a reduction in ovary and oviduct weight by Day 10. Liver, kidney and pancreas Zn concentrations increased approximately 10, 3, and 25-fold, respectively, in birds following 4 days of feeding the high Zn diets. The liver and kidney Zn concentrations returned to pretreatment concentrations within 18 days after the birds were fed the control diets (Day 22). The pancreas maintained higher Zn concentrations in comparison with the other tissues following withdrawal of the high Zn diet.

Animal Feed↗

PubMed1989

Bioavailability of manganese from feed grade manganese oxides for broiler chicks.

An experiment was conducted to study the relative biological availability of Mn from inorganic Mn sources using 288, 1-day-old male Cobb feather-sexed chicks. Chicks were fed a basal corn-soybean meal diet (82.5 ppm Mn, as-fed basis) ad libitum or the basal diet supplemented with 0, 1,000, 2,000, or 3,000 ppm Mn from reagent grade (RG) MnSO4.H2O, MnO RG, or feed grade (FG) Oxide A, B, or C for 21 days. Bone and kidney Mn concentrations were used to estimate bioavailability. Manganese source and level had no effect on chick performance. Uptake of dietary Mn by bone and kidney from all sources was highly linear (P less than .001). Based on multiple linear regression slopes from bone Mn concentrations, the relative bioavailability values of MnO RG and MnO FG A, B, and C were 81.9 +/- 6.0, 93.1 +/- 6.7, 75.0 +/- 3.6, and 70.3 +/- 5.7, respectively, compared with 100% for MnSO4; those based on kidney Mn were 85.7 +/- 7.9, 68.0 +/- 7.5, 52.2 +/- 4.2, and 53.0 +/- 7.3, respectively.

Animal Feed↗

PubMed1988

Plasma uric acid of broiler breeder and Leghorn male chickens: effect of feeding time.

Three trials were conducted to determine the effect of feeding time (meal-feeding) on plasma uric acid (PUA) levels of roosters. When sampling was done at various times postfeeding in two trials, PUA levels of broiler breeder males were highest at 2 h and lowest at 24 to 25 h postfeeding. In the third trial, meal-fed Leghorn males had the highest PUA levels at 2 h and lowest at 23.5 h postfeeding. Ad libitum-fed Leghorn males had a slow increase in PUA until 1100 h following lighting at 0500 h. The results suggest that feeding time in meal-fed birds and time of lighting in ad libitum-fed birds must be considered when determining PUA levels.

Animals↗

PubMed1988

Influence of Fermacto on the performance of laying hens when fed diets with different levels of methionine.

An experiment was conducted to determine the effect on laying hens of adding Fermacto at a level of 454 g/909 kg diet to diets containing various levels of supplemental methionine. The addition of Fermacto to the basal diet resulted in increased (P less than or equal to .05) production, egg mass, and feed intake while improving feed efficiency. A significant (P less than or equal to .05) main effect for supplemental Fermacto over all levels of added methionine was found for egg production and feed efficiency.

Animal Nutritional Physiological Phenomena↗

PubMed1988

Influence of Virginiamycin on yield of broilers fed four levels of energy.

An experiment was conducted to determine the effect of dietary Virginiamycin on processing yields of broilers fed four levels of energy. Body weights (catch, slaughter) and carcass weights (dry shell and ready-to-cook) were recorded. Shrink (holding weight loss), water uptake, shell yield, and ready-to-cook yield of the carcasses were calculated. Body weights were higher at higher energy levels and with addition of Virginiamycin to the diets. Weight loss due to shrink declined from 5.39 to 3.89% at higher dietary energy levels, but shrink was not affected by Virginiamycin. Water uptake was significantly higher for carcasses of birds fed the lowest dietary energy level (3.49%) than for carcasses of birds fed the two highest energy levels (2.89 and 3.03%); but differences among water uptake of carcasses of birds fed the three highest energy levels were not significant. Water uptake was unaffected by Virginiamycin. Increasing the dietary energy level resulted in higher ready-to-cook yields, from 61.7% yield at 2,271 kcal ME/kg to 65.4% yield at 2,953 kcal ME/kg. Yield was increased from 63.3 to 64.0% (P less than .01) by dietary Virginiamycin.

Animals↗

PubMed1988

Influence of 1,25-dihydroxyvitamin D3 on the performance of commercial laying hens.

An experiment was conducted to determine the influence of adding 4 micrograms/kg of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] to the diet of 68-wk-old commercial egg production-type hens. The addition of the 1,25(OH)2D3 to the diet for 21 days resulted in significantly decreased egg production, egg weight, and feed consumption, and significantly increased plasma P, and bone-breaking load. Specific gravity of eggs, plasma Ca, tibia ash, and fertility and hatchability of eggs were not significantly affected by the addition of 1,25(OH)2D3 to the diet.

Animals↗

PubMed1988

Estimation of the relative bioavailability of inorganic selenium sources for poultry. 1. Effect of time and high dietary selenium on tissue selenium uptake.

An experiment was conducted with male broiler-type chicks to study the effect of time and high dietary Se concentration on tissue Se uptake. A basal corn-soybean meal diet (.2 mg/kg Se, DM basis) was supplemented with 0, 3, 6, or 9 mg/kg Se (as-fed basis) as Na2SeO3 and fed ad libitum for 1, 2, or 3 wk. No toxic effect of Se was observed as expressed by mortality; however, there was a reduction in daily feed intake (P less than .01) at 6 and 9 mg/kg added Se, particularly at 3 wk, suggesting developing toxicosis. Selenium concentration in all tissues studied increased linearly (P less than .001) as dietary Se increased, especially in kidney and liver. Coefficients of determination and lambda criterion values were greatest in plasma, followed by liver, muscle, and kidney. It appeared that 1 wk would be an adequate length of time for further Se bioavailability studies based on tissue Se uptake from diets containing 3 to 9 mg/kg added Se.

Animals↗

PubMed1988

Estimation of the relative bioavailability of inorganic selenium sources for poultry. 2. Tissue uptake of selenium from high dietary selenium concentrations.

An experiment was conducted with 192 day-old male Cobb chicks to study tissue uptake of Se as an estimate of the bioavailability of supplemental inorganic Se sources fed at high dietary concentrations. A basal corn-soybean meal diet (.18 mg Se/kg diet, dry matter basis) was supplemented with 0, 3, 6, or 9 mg Se/kg diet (as-fed basis) as either reagent grade Na2SeO3, CaSeO3, or Na2SeO3 plus fumed amorphous carrier or 6 mg Se/kg diet as either Na2SeO4 or Se metal, and fed for 1 wk. No toxic effects were noted as expressed by mortality; however, there was a reduction (P less than .01) in feed intake and daily gain when 9 mg Se/kg diet was fed, suggesting onset of toxicosis. Selenium concentration in liver, kidney, muscle, and plasma increased linearly (P less than .01) as dietary Se increased from all sources. Selenium metal produced lower (P less than .01) Se concentrations in kidney and muscle than other supplemental sources. Multiple regression slope ratios were used to estimate relative bioavailability values of 100, 103, 99, 112, and 83 for Na2SeO3, CaSeO3, Na2SeO3 + carrier, Na2SeO4, and Se metal, respectively. When these ratios were corrected for the analyzed dietary Se concentration, relative values were 100, 96, 94, 109, and 81 for the above sources, respectively.

Animals↗

PubMed1987

Prevalence of extracranial carotid artery disease: a survey of an asymptomatic population with noninvasive techniques.

To investigate the prevalence of internal carotid arterial stenosis in an unselected asymptomatic population over 50 years of age, 102 volunteers from one church congregation were studied with ultrasonic arteriography, spectral analysis, and ocular pneumoplethysmography. Fifty subjects were 50 to 59 years old; 33 were 60 to 69 years of age; and 19 were older than 70 years. Forty-five were men and 57 were women. Risk factors included diabetes mellitus (4%), heart disease (9%), hypertension (24%), peripheral vascular disease (20%), and smoking (46%). Disease was found in 11 subjects (10.8%). Of the 204 internal carotid arteries, 13 (6.4%) were abnormal. Two vessels had 20% diameter stenosis; four had stenoses of 20% to 39%; five had stenoses of 40% to 59%; one had a stenosis of 60% to 79%; and one was occluded. Stenoses greater than 40% occurred in 4% of the 50 to 59 years of age group, 6% of the 60 to 69 years of age group, and 11% of the greater than 70 years of age group. Although the prevalence of carotid stenosis was increased in all subjects who had risk factors, only the association with heart disease reached statistical significance. These results indicate that carotid stenosis is present in an appreciable number of asymptomatic subjects over the age of 50 years and suggest that its prevalence is associated with age and other risk factors.

Age Factors↗

PubMed1987

Nutritive value of new cultivars of triticale and wheat for broiler chick diets.

Three experiments were conducted with broiler chicks from 1 to 21 days of age to evaluate Florida 301 variety of wheat and Beagle 82 variety of triticale. In Experiment 1, a completely randomized design (CRD) was used for five dietary treatments: yellow corn-soy (control), triticale-soy, yellow corn-triticale-soy, wheat-soy and yellow corn-wheat-soy. Diets were balanced to maintain equal levels of sulfur amino acids and lysine and were kept isocaloric (3,124 kcal/kg) using corn oil. In Experiment 2, a CRD was used for 10 dietary treatments. Each grain was substituted partially and totally for corn on both iso and nonisocaloric basis. Animal fat was the supplemental fat source. In Experiment 3, a CRD was used for 8 dietary treatments. Each grain was substituted for corn isocalorically using corn oil, animal fat, or both as supplemental fat sources. Results from these experiments showed that Florida 301 wheat is an excellent cereal grain for broiler chicks as measured by feed efficiency and growth response, which was numerically but not significantly greater than with a corn-soy control diet. Growth response was inconsistent with Beagle 82 triticale throughout the three experiments. However, feed efficiency was better with triticale diets than corn-based diets.

Animal Feed↗