Biomedical subjects

R M Hulet

Publications and source records attributed to R M Hulet.

At least 19 recordsLinked to original sources

PubMed2006

Growth and foliar nitrogen status of four plant species exposed to atmospheric ammonia.

A chamber study was conducted to evaluate the growth response and leaf nitrogen (N) status of four plant species exposed to continuous ammonia (NH3) for 12 weeks (wk). This was intended to evaluate appropriate plant species that could be used to trap discharged NH3 from the exhaust fans in poultry feeding operations before moving off-site. Two hundred and forty bare-root plants of four species (Juniperus virginiana (red cedar), Gleditsia triacanthos var. inermis (thornless honey locust), Populus sp. (hybrid poplar), and Phalaris arundinacea (reed canary grass) were transplanted into 4- or 8-L polyethylene pots and grown in four environmentally controlled chambers. Plants placed in two of the four chambers received continuous exposure to anhydrous NH3 at 4 to 5 ppm while plants in another two chambers received no NH3. In each of the four chambers, 2 to 4 plants per species received no fertilizer while the rest of the plants were fertilized with a 100 ppm solution containing 21% N, 7% phosphorus, and 7% potassium. The results showed that honey locust was the fastest-growing species. The superior growth of honey locust among all species was also supported by its total biomass, root, and root dry matter (DM) weights. For all species there was a trend for plants exposed to NH3 to have greater leaf DM than their non-exposed counterparts at 6 (43.0 vs. 30.8%; P = 0.09) and 12 wk (47.9 vs. 36.6%; P = 0.07), and significantly greater (P <or=0.05) leaf N content at 6 (6.44 vs. 3.67%) and 12 wk (7.05 vs. 3.51%) when exposed to NH3. Numerically greater leaf DM due to NH3 exposure was also consistently measured in poplar at both sampling periods. Hybrid poplar, as well as honey locust and reed canary grass, deposited 1.5 to 2-fold greater N in their leaves than red cedar tissues as a result of NH3 exposure compared to non-exposed plants. Regardless of the effect of NH3 on foliar color and damage score of the plants, the increase of foliar N content (g 100 g-1 of fresh foliage weight) after NH3 exposure at 6 and 12 wk was 0.45 and 0.87 for grass,1.25 and 1.34 for locust, and 2.67 and 6.09 for poplar. However, only honey locust likely benefited from ambient NH3 as indicated by its consistent leaf color quality and lower damage score, compared with other species that were adversely affected by atmospheric NH3.

Air Pollutants↗

PubMed2003

Analysis of the nonlinear dynamics of daily broiler growth and feed intake.

Daily BW velocity (BWV) and acceleration (BWA) of individual birds have been demonstrated to be oscillatory. Daily feed intake velocity (FIV) and acceleration (FIA) were hypothesized to be oscillatory and to have a positive relationship with BWV and BWA, respectively. Forty-eight male broiler chicks were individually caged and provided a commercial starter feed ad libitum for 49 d. BW and feed intake (FI) were measured daily. Experiment 1 confirmed that, on a daily basis, BWV, BWA, FIV, and FIA were oscillatory. There was a positive correlation between BW and FI, BWV and FIV, and BWA and FIA. A Kohonen neural network (KNN) clustered BWV and FIV into two and three sequential phases. BWA and FIA analysis did not make definitive clusters. In experiment 2, it was hypothesized that correlation between BWV and FIV would increase with feeding of grower and finisher rations. It was hypothesized that KNN three phase clusters may provide more biologically ideal times of ration change (TORC) for starter, grower, and finisher rations. For 49 d, five treatments, nine birds per treatment, were fed starter, grower, and finisher rations singly or together with dietary changes according to an industry or KNN-determined TORC. Evaluation was made of BW, FI, and carcass characteristics. No significant mean differences were found. Compared to the industry group, the KNN group demonstrated significantly improved uniformity (i.e., smaller SD) of BW (bled out), FI, dressing percentage, and some of the carcass characteristics. Differences between KNN and industry TORC results might have been related to the length of time the birds were fed the starter, grower, and finisher diets.

Aging↗

PubMed2000

Effects of photoperiod and melatonin on lymphocyte activities in male broiler chickens.

Understanding the role of the pineal gland in regulating the immune response and the role of photoperiod in influencing pineal gland secretions are becoming increasingly important. The purposes of the present experiments were to investigate the effects of different photoperiod regimens on T- and B-lymphocyte activities in broiler chickens. Next, the influence of different photoperiod regimens on the responsiveness of lymphocytes to melatonin in vitro was examined. The effect of melatonin in vitro on lymphocyte activities was also studied, regardless of the photoperiod received. Finally, the effects of photoperiod on the profiles of different splenocyte cell types were investigated. To study the effect of photoperiod on lymphocyte activities, different photoperiod regimens were used. These were: constant lighting, 23 h light:1 h darkness; intermediate lighting, 12 h light:12 h darkness; and intermittent lighting, 1 h light:3 h darkness. Peripheral blood and splenic lymphocyte activities were tested at 3 and 6 wk of age by performing a mitogen cell-proliferation assay with a polyclonal T-cell mitogen, concanavalin A (Con A), and T-dependent B-cell mitogen, pokeweed mitogen (PWM). To study the effect of photoperiod on the responsiveness of lymphocytes to melatonin in vitro or the effect of melatonin in vitro on lymphocyte activities regardless of photoperiod received, lymphocytes from the chickens that were exposed to the different photoperiod regimens were incubated with mitogen and different concentrations of melatonin. To study the effect of photoperiod on profiles of different cell types, the percentages of splenocyte subpopulations from birds exposed to different photo-periods were determined using flow cytometry with CD4+, CD8+, CD3+, and B-cell markers. The results of these studies indicate that splenic T and B lymphocytes from 6-wk-old chickens grown in intermittent lighting had higher activities than those from chickens grown in constant lighting. Peripheral blood and splenic lymphocytes from chickens raised under constant lighting were more responsive to melatonin in vitro than those from chickens raised under intermittent lighting. This difference in response may be due to lower levels of melatonin in birds receiving constant lighting, making them more sensitive to melatonin in vitro. Melatonin in vitro enhanced the mitogenic response of peripheral blood T lymphocytes from 6-wk-old chickens, splenic T lymphocytes from 3-wk-old chickens, and splenic T and possibly B lymphocytes from 6-wk-old chickens. Finally, intermittent lighting increased the percentages of splenic CD4+, CD8+, and CD3+ cells but not B-cell subpopulations at 6 wk of age, presumably because of increased levels of melatonin in birds receiving intermittent lighting. Our results re-emphasize the importance of melatonin in regulating host immune response; this regulation could be accomplished through exposing broiler chicks to intermittent lighting.

Animals↗

PubMed1999

Identifying potentially subfertile toms via a sperm-binding assay.

We evaluated the utility of the commercial version of a new sperm-egg binding assay for detection of differences in sperm quality in samples of turkey semen from individual toms. Each sample had a swirl of 2 or more on a scale of 0 to 4. For assays conducted with fresh semen at 4 x 10(6) sperm per well, values ranged from 0.11 to 12% sperm bound to an extract of perivitelline membrane. Within-male variation averaged 0.17 percentage units, based on three ejaculates per male evaluated. Two experiments compared fertility and hatch for hens after weekly insemination with pooled semen from subpopulations of toms classified as having sperm with LOW or HIGH binding. Average fertility and hatch were lower (P < 0.05) for eggs laid by hens inseminated with semen from LOW toms in one experiment. In another experiment, hen fertility was not different between treatments after insemination during Weeks 32 to 39; however, a sharp decline in hatch was observed only for hens inseminated with semen from LOW toms after 40 wk of age. With semen from HIGH toms, hatch remained at > or = 80%. For these experiments, approximately 7% more poults were obtained from hens inseminated with semen from HIGH toms. We demonstrated that the sperm-egg binding assay detects differences in sperm quality between individuals, and these differences influence fertility.

Animals↗

PubMed1995

Endogenous amylase levels and response to supplemental feed enzymes in male turkeys from hatch to eight weeks of age.

Amylase and xylanase enzyme concentrations in the pancreas, small intestine, and crop were measured in Nicholas male poults fed diets with and without supplemental amylase and xylanase from 0 to 8 wk of age. Eight birds from each of three diets (control, amylase-supplemented, xylanase-supplemented) were killed every 3 d to determine the amylase and xylanase activity within the pancreas, small intestine, and crop. Pancreatic organ weight was not affected by diet, indicating an absence of dietary amylase effect upon pancreatic tissue growth. Pancreatic amylase activity was not consistently affected by diet. Amylase activity within the intestinal chyme increased sporadically with dietary amylase supplementation over the control and xylanase-supplemented diets. Increasing supplemental amylase activity levels may provide more conclusive evidence of an additive effect of dietary amylase and endogenous amylase activity. Xylanase supplementation within the feed did not affect endogenous amylase activity.

Amylases↗

PubMed1995

Effects of protein level and enzyme supplementation upon growth and rate of digesta passage of male turkeys.

An experiment was conducted to determine the effect of feeding enzyme supplements (Avizyme and protease) at two levels of dietary crude protein (24 and 28%) to male turkeys from 0 to 5 wk of age. The Avizyme-protease enzyme mixture was fed at five concentrations within each protein level in an effort to determine an optimal level of supplementation. Enzymes were added to the 24% protein diet to determine whether the supplements would enhance the growth performance of birds fed the lower protein diet to the level of those fed the 28% protein diet. Rate of passage was evaluated to determine whether an ANF effect corresponded to enzyme concentration or protein level. Dietary protein level significantly influenced growth. Birds fed the 28% protein diet had improved body weight gain, feed consumption, and feed efficiency of 11.5, 6.5, and 4.4%, respectively, when compared with birds fed the 24% protein diet. Enzyme addition to the 24% protein corn-soybean meal diet produced a graded response but did not improve growth over the control. Although enzyme supplementation improved poult utilization of the 24% protein diet, growth and feed utilization were not equal to the performance of the poults fed the 28% protein diet. When the enzyme mixture was added to the 28% diet, performance was not consistently altered. Rate of digesta passage was not different between the levels of dietary protein or among levels of enzyme supplementation, indicating that the applied protein levels did not deleteriously affect nutrient utilization.

Animal Feed↗

PubMed1995

Growth and intestinal morphology of male turkeys as influenced by dietary supplementation of amylase and xylanase.

Three diets, a control and two diets supplemented with an enzyme cocktail premix containing either amylase or xylanase, were each fed to 100 male poults (10 replicates of 10 poults per pen) from 0 to 5 wk of age to observe the effects upon body weight gain, feed intake, and feed efficiency. The amylase-supplemented diet significantly increased feed efficiency through the first 2 wk and significantly increased body weight gain and feed intake through the first 3 wk. Xylanase supplementation did not improve growth or feed efficiency over the control. Mean villus length within the jejunum and ileum was significantly increased at 2 and 3 wk of age by dietary supplementation of amylase when compared with the control and xylanase diets. These findings suggest that the increased growth associated with the amylase diet during 0 to 3 wk can, in part, be explained by the increase in absorptive surface area, allowing for increased digestion of available nutrients coupled with increased enzyme activity for carbohydrate degradation from the supplemental enzymes.

Amylases↗

PubMed1995

Improving phosphorus availability in soybean meal for broilers by supplemental phytase.

A 21-d experiment was conducted with day-old male broilers (n=840) to evaluate the effectiveness of supplemental phytase for improving the availability of phytate P in soybean meal when varying levels of P were fed. The semi-purified basal diet (.18% phytate P) contained soybean meal as the only protein source. Seven levels of phytase (0, 200, 400, 600, 800, 1,000, and 1,200 U/kg diet) were added to diets formulated to contain .20, .27, or .34% nonphytate P (nP; or .38, .45, and .52% total P, respectively). The desired levels of nP in the three basal P diets were achieved by adding varying amounts of defluorinated phosphate. A 2:1 Ca:total P ratio was maintained in all diets. Body weight gains and feed intake were improved (P < .001) by phytase at all nP levels, but the magnitude of response was greatest at low nP levels, resulting in an nP by phytase interaction (P < .01). Gain:feed was unaffected by phytase addition. A high mortality (35 to 45%) was observed for the .20 and .27% nP diets without added phytase, but this declined to normal levels with the addition of 200 to 400 U phytase/kg diet. Ash percentage of toes and tibia and shear force and stress of tibia increased with added phytase. These responses clearly show that the phytate-bound P in soybean meal was made more available to broilers by microbial phytase, and the total response was related to the phytase and nP/total P levels. Based on the high R2 values for the second order translog equations, BW gain, feed intake, and toe ash percentage were the most sensitive indicators to assess P availability, followed by tibia force and ash percentage. Derived nonlinear and linear equations for BW gain and toe ash percentage at the two lower nP levels were used to calculate P equivalency values of phytase for inorganic P. Using the average function of P released ( gamma ) by microbial phytase ( chi ) derived with nP levels of .20 and .27% for BW gain and toe ash percentage, gamma = 1.120 - 1.102e-.0027chi, 1 g of P could be released with 821 U of phytase. The amount of P released increased with increasing levels of phytase, but the amount of P released per 100 U of phytase decreased. Released P ranged from 31 to 58% of phytate P for 250 to 1,000 U of phytase/kg of diet.

6-Phytase↗

PubMed1995

Response of turkey poults to tiered levels of Natuphos phytase added to soybean meal-based semi-purified diets containing three levels of nonphytate phosphorus.

A 3-wk feeding trial using 920 day-old turkey poults was conducted to evaluate the addition of seven levels of phytase (Natuphos; 0, 200, 400, 600, 800, 1,000, and 1,200 U/kg of diet) to diets containing three levels of nonphytate P (nP) (.27, .36, and .45%). A positive control diet contained .60% nP. Semi-purified basal diets contained soybean meal as the only protein source. The increase in BW gain from added phytase was greatest for the lowest nP diet (nP by phytase interaction, P < .001). At .27% nP, gains improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. At .36 and .45% nP, increases in gains were observed only for 200 U of phytase/kg of diet. The highest phytase addition to.36 and .45% nP diets produced gains equal to those of the positive control diet. Feed intake increases paralleled those of BW gains. Gain:feed was lowest for the .27% nP diets without phytase, but improved (P < .001) to 800 U of phytase/kg of diet and then reached a plateau. The high incidence of leg disorders and high mortality (40%) observed for the poults fed the .27% nP diet without added phytase declined with the addition of 200 to 400 U of phytase/kg of diet. Ash percentage of toes and tibias increased as the levels of nP (P < .001) and phytase (P < .01) increased; the magnitude of the response to phytase decreased as nP in the diet increased, resulting in an nP by phytase interaction (P < .001). Tibial shear force and stress responded in a similar manner to increasing levels of nP and added phytase. Results show that 652 U of microbial phytase is equivalent to 1 g of P from defluorinated phosphate in turkey starter diets using soybean meal as the only source of phytate P. The response per 100 U of phytase decreased as the total amount of phytase added was increased.

6-Phytase↗

PubMed1993

Supplemental dietary L-tryptophan effects on growth, meat quality, and brain catecholamine and indoleamine concentrations in turkeys.

1. An experiment was conducted to investigate the effects of feeding supplemental tryptophan during the two weeks before market on growth, mortality during transportation, meal quality and brain neurotransmitter concentrations in male turkeys. 2. Brain serotonin, 5-hydroxyindoleacetic acid and norepinephrine concentrations were increased dose-dependently with 1.0, 2.0 and 3.0 g/kg supplemental dietary tryptophan. 3. Supplemental dietary tryptophan had no effect on body weight gain, food intake, food efficiency or mortality. 4. Carcase and individual thigh weights were significantly heavier in those birds fed 1.0 g/kg supplemental tryptophan.

Animal Feed↗

PubMed1992

The effect of light source and intensity on turkey egg production.

The effect of light source and intensity on egg production, fertility, hatchability, egg weight, and shell quality in turkey hens was investigated. Turkey hens were exposed to either incandescent, high-pressure sodium vapor (HPSV), or daylight fluorescent (FL) lights at an intensity of 21.6 1x during the growth phase (after 8 wk). During the breeder phase, hens were assigned to the same light sources at light intensities of either 53.8 or 166.4 1x in a 3 x 3 x 2 factorial arrangement of treatments. Light source during the growth phase had no significant effect on subsequent egg production, egg weight, fertility, or hatchability. Egg production, shell quality, fertility, and hatchability were also unaffected by light source or intensity during the breeder phase. Egg weight was significantly increased in hens exposed to HPSV compared with incandescent lights during the breeder phase. The HPSV and FL lights can be used effectively for turkey breeder hens both during the prebreeder and breeder periods. Furthermore, light intensities of 53.8 and 166.4 1x appear to be equally effective in stimulating production.

Animal Husbandry↗

PubMed1992

Effects of light sources and the presence or absence of males on reproduction of female breeder turkeys.

The effects of sodium vapor (SV), daylight fluorescent (DF), and incandescent (IN) light sources and the influence of the presence or absence of males on reproduction of female turkeys were evaluated. Hens under SV and DF lights consistently laid more eggs than those under IN lights. There were no significant differences in hen-day egg production among hens in the physical presence of males and hens allowed visual and vocal contact with males. However, hen-day egg production was significantly lower for females in pens in which males were absent. Fertility, hatchability, days to first egg, egg weight, and egg specific gravity were unaffected by light source treatments or by the presence or absence of males in pens of females.

Analysis of Variance↗

PubMed1991

Protein and energy self-selection of turkey hens. Serum prolactin and luteinizing hormone concentrations.

1. The incidence of broodiness was four times as high among turkey hens fed a complete control diet than among hens allowed to self-select their diet from two different feed sources, one being relatively high in protein and the other relatively high in energy (i.e. split-diet). 2. Among non-broody birds, hens fed the split-diet had a significantly lower serum prolactin concentration in the third month of production as compared to control hens. 3. Hens in their second season of egg production had significantly lower serum luteinizing hormone concentrations during the latter stages of egg production than did first season hens.

Animals↗

PubMed1991

Self-selection of dietary protein and energy by turkey breeder hens.

1. An experiment was conducted to determine the effects of self-selection of dietary protein and energy by turkey hens on reproductive performance in a warm environment. 2. Dietary self-selection had no significant effect on egg production, egg weight, or body weight of turkey hens. 3. Fertility and hatchability of eggs produced by self-selecting hens were significantly reduced compared to eggs from control hens fed on a complete diet. 4. Protein intake was significantly reduced among self-selecting hens when compared to control hens fed on a complete diet (P less than or equal to 0.001). 5. Food and energy intake decreased as the ambient temperature increased. Nevertheless, protein intake of self-selecting hens increased over the course of egg production despite decreasing food intake. Therefore, self-selecting hens preferred a diet with a greater protein content (g protein/kg diet) in the last 10 weeks of egg production than during the first 10 weeks of egg production.

Animal Feed↗

PubMed1990

Protein and energy self-selection by turkey hens: reproductive performance.

1. The influence of protein and energy self-selection on the reproductive performance of turkey hens was investigated. Large White turkey hens were fed on either a complete diet (185 g CP/kg, 11.30 MJ ME/kg) or were provided with a choice between a high protein-low energy diet (348 g CP/kg, 7.74 MJ ME/kg) and a high energy-low protein diet (81 g CP/kg, 13.39 MJ ME/kg). 2. Egg production, egg weight, and the fertility and hatchability of eggs produced were not significantly affected by the dietary treatments (P greater than 0.05). 3. While energy intake was not significantly different between groups, protein consumption decreased by approximately 40% (P less than or equal to 0.001) among self-selecting hens compared to hens fed on the complete diet. This resulted in a 10% (P less than or equal to 0.05) reduction in the food intake in the self-selecting birds.

Animal Feed↗

PubMed1990

Effect of light sources and light intensity on growth performance and behaviour of female turkeys.

1. The effect of different light sources (incandescent, sodium vapour, daylight fluorescent and warm fluorescent) and light intensities (10.8 and 86.1 lux) on growth performance and behaviour of female turkeys was investigated in two experiments conducted at different times of the year. 2. Although light source influenced body weight and efficiency of food utilisation, there was no consistent effect between experiments in favour of any particular source. 3. Light intensity had no effect on body weight, efficiency of food utilisation or behaviour.

Animals↗

PubMed1990

Genetic influences on seasonal decline in the fertility of female turkeys.

Daughter-dam pairs of white, large-bodied, turkey breeder hens (108) were reared under similar husbandry conditions, and their egg production and fertility were monitored from the onset of lay for 6 mo. On a monthly basis, percentage fertility was compared by daughter-dam regressions to estimate heritabilities. The heritability estimates were 18.36, and 38%, respectively, for the 2nd, 3rd, and 4th mo of lay; but no estimates could be made for Months 1, 5, or 6. The heritability of percentage fertility for Months 2, 3, and 4 combined was 42%. The proportion of hens that remained above 75% fertility declined each month for both dams and daughters, except in one case. Thus, the seasonal decline in fertility appears to have a genetic component.

Animals↗

PubMed1990

Influence of light sources on the growth and reproduction of large white turkeys.

The present study evaluated the effects of sodium vapor (SV), daylight fluorescent (FL) and incandescent (IN) light sources on the growth and reproduction of primary turkeys. Large White turkeys (90 sire line and 324 dam line) were reared by sex under one of the three light sources from 8 to 22 wk of age. At 22 wk of age, all males and females were preconditioned under their assigned light source, but the photophase was restricted to 6 h per day at an intensity of 21.6 lx. At 33 wk of age, the males were exposed to 16 h of light per day under the same light sources in which they were reared. At 35 wk of age, the females were reassigned to the various light sources in order to achieve all possible combinations of adolescent and breeder light-source treatments. Sixteen hours of light per day were provided at an intensity of 53.8 lx during a 20-wk cycle of egg production. The body weights of males and the feed efficiencies of males and females were unaffected by the adolescent light-source treatment. The females were significantly heavier under SV than those under FL and IN lights. Hen-housed egg production was significantly higher for females exposed to SV and FL lights versus IN during the first 10-wk production period. Hen-day egg production was significantly higher for females given FL than for those provided SV and IN lights. However, total hen-housed and hen-day production was unaffected by either adolescent or breeder light-source treatments. Fertility, hatchability, days to first egg, egg weight, and egg specific gravity were also unaffected by either the adolescent or breeder light-source treatment. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗