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Biomedical subjects

G A Milliken

Publications and source records attributed to G A Milliken.

14 recordsLinked to original sources
PubMed2001

Cholinesterase activity:muscarinic receptor ratios in canine and feline brains.

In response to findings that brain cholinesterase (ChE): muscarinic cholinergic receptor density (mChR) ratio is highly conserved between bird species (I), this study investigated the conservation of brain ChE:mChR between 2 mammalian species. Whole brains of 7 normal greyhounds, 14 normal non-greyhound dogs, and 8 normal cats, were assayed for ChE, mChR and protein. The same assays were made on cerebrum, cerebellum and brainstem from the greyhounds and 6 of the non-greyhound dogs. The Ellman assay was used to measure serum ChE activity, mChR were labelled with tritiated quinuclidinyl benzilate, and protein was measured by Lowry assay. Brain ChE:mChR was not highly conserved between the species. There was a statistically significant difference in brain mChR between greyhounds and non-greyhounds but this did not translate to a statistically significant difference in mean ChE:mChR. Measurement of ChE:mChR is unlikely to be useful in endangered carnivores for which normal ChE levels are unknown, because it cannot be assumed that endangered species would have the same ChE:mChR as their domestic relatives.

Animals↗
PubMed1999

Interrelationships among evaluations of beef longissimus and semitendinosus muscle tenderness by Warner-Bratzler shear force, a descriptive-texture profile sensory panel, and a descriptive attribute sensory panel.

The objective of our study was to examine the interrelationships among Warner-Bratzler shear force (WBSF) determinations, evaluation by a highly trained descriptive-texture-profile (DTP) sensory panel, and evaluation by a trained descriptive attribute (DA) sensory panel as affected by muscle fiber orientation of samples and shear-blade type. Longissimus lumborum and semitendinosus muscles (n = 18 of each) were cut into 2.54-cm steaks, which were cooked to 71 degrees C. Cores were obtained with two methods (parallel to the muscle fiber orientation and perpendicular to the cut steak surface), used for WBSF determinations with the typical V-shaped blade and modified WBSF determinations with a flat blade, and presented to the DTP and DA sensory panels. The V-shaped blade resulted in 1.4 to 2.5 kg lower (P < .05) mean WBSF values than the flat blade for both muscles. Cores taken parallel to the longissimus muscle fiber orientation had .64 kg higher (P < .05) mean WBSF values than cores taken perpendicular to the cut steak surface. Both panels detected differences among carcass replications; however, a panelist x replication effect (P < .05) occurred for the DA panel. Both panels detected differences (P < .05) in muscle fiber orientation for attributes related to tenderness. Correlations between sensory panel scores and WBSF values were dependent on blade type and coring method. Blade type and coring method had greater effects on correlations between sensory scores and WBSF values for the DTP panel than for the DA panel. Correlations between scores by both sensory panels and WBSF values were comparable. The more highly trained DTP panelists were more consistent in their evaluations of texture attributes; however, they were more sensitive to muscle fiber orientation. Both panels were effective in detecting differences among carcass replications.

Animals↗
PubMed1997

Estimating the maximum effective dose in a quantitative dose-response experiment.

A simulation study was conducted to compare several procedures for estimating the maximum effective dose in a quantitative dose-response experiment. Using four equally spaced dose levels, data were generated from four different model types: the quadratic growth curve, the Mitcherlich growth curve, the linear-linear plateau spline model, and the quadratic-linear plateau spline model. Each model type was parameterized to create three different model ranges, and for each range, data were generated from populations with three different standard deviations. The existence of unique dose-response curves is assumed; thus, all the procedures compared in this paper require that the data have been modeled by a polynomial or nonlinear regression model. An attempt was made to fit each generated data set with each of the four model types. Maximum effective dose estimation procedures were applied to a data set only when the data were adequately described by a given model. The stimulation indicated that the estimate of the maximum effective dose is influenced more by the choice of model than by the method of estimation. Because of the consistently low estimates produced when the data were modeled by the linear-linear plateau spline, this model is not recommended for use an maximum effective dose estimation experiments. The simulation also demonstrated that the design failed to provide sufficient information about the form of the dose-response curve. Designs with more than four dose levels should be considered.

Animals↗
PubMed1995

Body weight, heart weight, and heart-to-body weight ratio in greyhounds.

Heart and body weights were obtained from 230 Greyhounds during necropsy. Sex and age were recorded for each Greyhound. Twenty-nine racing and 21 nonracing Greyhounds among the 230 dogs were compared. Heart-to-body weight ratio was calculated. Statistical analysis was done to determine the effects of age, sex, and racing on heart and body weights and heart-to-body weight ratio. In adult Greyhounds, mean +/- SD body weight was 28.4 +/- 3.1 and 31.5 +/- 2.8 kg, heart weight was 355.6 +/- 52.8 and 381.4 +/- 50.8 g, and heart-to-body weight ratio was 1.3 +/- 0.2 and 1.2 +/- 0.2% for females and males, respectively. Heart and body weights were significantly different between sex and age groups and among nonracing and racing males. However, heart-to-body weight ratio was not significantly different among age, sex, or racing groups.

Aging↗
PubMed1992

Beak trimming effects on beak length and feed usage for growth and egg production.

Two experiments were conducted to compare beak treatment effects on pullets of three genetic stocks. Within each stock, equal numbers were assigned to three treatments: no beak trimming (IN), beak trimming once (1X), and beak trimming twice (2X). Beak treatment, genetic stock, and age effects along with interactions among main effects were examined for production-associated traits during rearing and brief periods of early egg production. Beaks of 1X and 2X pullets remained shorter than those of IN pullets through final measurements at 36 and 32 wk of age in Experiments 1 and 2, respectively. However, differences in beak length decreased as age increased. Upper beaks of 2X pullets remained shorter than those of 1X pullets, but lower beaks of 1X and 2X pullets did not differ by 20 wk in Experiment 2. Weight gains, feed usage, and efficiency of growth were affected by beak treatments. Beak trimming reduced gains, feed eaten, feed wasted, and total feed used, and 2X pullets used their feed more efficiently for weight gain and egg production. A general decrease occurred in differences among beak treatments for weight gains, feed eaten, feed wasted, and efficiency of gains with increasing age during rearing. Nevertheless, significant differences in feed consumed, feed wasted, and efficiency of feed used for egg production indicated an economic advantage in favor of beak trimming.

Aging↗
PubMed1992

Research note: effects of beak trimming and genetic stock on rate of mash consumption and feeding-related behavior in egg-strain pullets.

Pullets whose beaks were trimmed once (at 9 days) and twice (at 9 days and 9 wk) were able to ingest feed, in the form of mash, more rapidly under competitive feeding conditions and at least as rapidly in the absence of competition as pullets with intact beaks. Tests of feeding rate, when pullets fed in groups, were carried out after a feed deprivation period of 7 h at ages of 10 through 16 wk. Similar tests were done at 18 wk, when pullets fed without competition. Genetic stock and age had significant effects on frequency of agonistic acts at the feeder and displacements from the feeder during 5-min tests under competitive feeding conditions. Age influenced the number of pullets feeding simultaneously and amount of feed eaten per pullet during the same feeding tests. No interactions were detected among beak treatment, stock, and age for feeding-related behaviors or rate of feed consumption during competitive feeding. In noncompetitive feeding tests, genetic stock affected feeding rate but no stock by beak treatment interaction was present.

Aging↗
PubMed1987

Effect of wheat and high-moisture sorghum grain fed singly and in combination on ruminal fermentation, solid and liquid flow, site and extent of digestion and feeding performance of cattle.

Two experiments were conducted to determine how varying the proportion of wheat (W) and high-moisture sorghum grain (SG) in 80% grain dies would affect ruminal fermentation, liquid and solid flow, site and extent of digestion (Exp. 1) and feeding performance of cattle (Exp. 2). In Exp. 1, three ruminal, duodenal and ileal cannulated steers (average weight 295 kg), fed at 1.54% of body weight, were used in a six-period crossover design. Treatments were: W, 50W:50SG (W:SG) and SG. Increasing wheat level decreased ruminal pH, molar proportion of acetate, and acetate:propionate ratio (P less than .05) and increased (P less than .05) L-lactate concentration, molar proportions of propionate and valerate and total volatile fatty acid concentration. Ruminal liquid dilution and outflow rates were faster (P less than .05) and retention time was shorter (P less than .05) for the W diet. Duodenal and ileal liquid flow increased (P less than .05), and solid flow decreased (P less than .05), as dietary level of wheat increased. Apparent ruminal digestion (% of intake) of dry matter (DM) and organic matter (OM) was greater (P less than .01) with the wheat-containing diets. Intestinal DM and OM digestion (percent of intake) was higher (P less than .05) with the SG and W:SG diets. Ruminal, small intestine, large intestine and total tract starch digestion (percent of intake) was 93.5, 5.6, .7, 99.8, 71.5, 20.4, 5.7, 97.6; and 48.0, 32.5, 10.5, 91.0 with the W, W:SG and SG diets, respectively. In Exp. 2, group-fed (24 pens) steers (avg initial weight 341 kg) were fed ad libitum once daily for 121 d. Treatments were: W, 67W:33SG, 33W:67SG and SG. Rates of gain (kg/d) with the W (1.32), 67W:37SG (1.33) and 33W:67SG (1.30) diets were similar (P greater than .05), but faster (P less than .05) than those with the SG diet (1.16). Feed intake was lower (P less than .01) with the W and 67W:33SG diets, but the wheat-containing diets were utilized more efficiently (P less than .01). Increasing the proportion of wheat in sorghum grain feedlot diets improved cattle performance by optimizing ruminal and post-ruminal digestion.

Animal Feed↗
PubMed1987

Effects of body weight groupings on productivity, feather loss, and nervousness of caged hens.

Two experiments compared performance traits, feather loss, and nervousness of hens kept in contrasting homogeneous and heterogeneous body weight groupings. In addition, 15-day periods of daily uterine palpating vs nonpalpating for an egg in the uterus were compared for effects on egg production. Eighteen-wk-old pullets were weighed and characterized as light, medium, or heavy and housed in laying cages at 19 wk for a 50-wk production period. In Experiment 1, two hens were placed in each cage and there were three treatment groups: both light (L), mixed or 1 heavy and 1 light (X), and both heavy (H). In Experiment 2, three pullets were used per cage; a medium-weight group (M) was included and mixed cages included 1 heavy, 1 medium, and 1 light weight bird. In an ancillary experiment, 50-wk-old hens were also palpated or not palpated for an egg in the uterus over a single 15-day period. Results indicated that differences that were present in initial body weight groups persisted over the 50-wk period in Experiments 1 and 2 with no effect of weight grouping on body weight gain, egg production, and livability. Differences that were associated with weight groups were: age at sexual maturity, egg weight, egg mass, and nervousness score. No differences in mean feather scores were present among weight groups. Comparisons between individual hens of the same relative weight but kept in homogeneous or heterogeneous weight groups failed to indicate competitive advantages or disadvantages in egg production, feathering, and nervousness scores. No significant associations were found between nervousness scores of individual hens and other traits except for total body weight gain in Experiment 1, in which individuals that gained more were less nervous in the X groups (r = -.55). Palpating hens daily for two 15-day periods significantly increased hen-day egg production in Experiment 2 and nonsignificantly in Experiment 1, with no influence of palpation on hen-day egg production, egg weight, or egg mass in the ancillary experiment.

Animal Husbandry↗
PubMed1987

Density and group size effects on caged hens of two genetic stocks differing in escape and avoidance behavior.

Hens of two moderately inbred White Leghorn stocks, known to differ significantly in escape and avoidance behavior, were compared for productivity traits, nervousness, and feather loss when housed four or eight per cage at densities of 348 (high), 464 (medium), and 580 (low) cm2/bird. Differences were found between stocks in sexual maturity, egg production traits, body weights, nervousness, and feather loss. The more nervous strain lost more feathers. Highest density housing depressed performance and increased nervousness and feather loss, but differences were generally lacking between the medium and lowest density housing. Group size effects were not detected for productivity traits, but hens kept in groups of eight had increased nervousness and feather loss. No interactions were detected between stocks and density, stocks and group size, or density and group size.

Animals↗
PubMed1986

Heat production of cattle acclimated to cold, thermoneutrality and heat when exposed to thermoneutrality and heat stress.

Four Hereford X Red Angus yearling steers were acclimated to each of the following environments; cold (3 C), thermoneutrality (TNZ; 20 C) and heat (35 C). Intake was equalized for all treatments at 4.9 X kg X head-1 X d-1 (2.9 Mcal metabolizable energy/kg). Heat production, respiration rate and rectal temperature were determined after 3- and (21-h later) 24-h exposures to thermoneutral and heat stress test-temperatures: 25, 30, 32.5, 35, 37.5 and 40 C. Thermoneutral heat production (kcal X kg-.75 X d-1), after 3- and 24-h exposures, was greater (P less than .05) for the cold-acclimated cattle (139.6 +/- 5.0 and 153.0 +/- 5.8) as compared with the TNZ-acclimated cattle (117.7 +/- 5.0 and 121.6 +/- 5.8). Heat production of the heat-acclimated cattle after 3- and 24-h exposures to thermoneutrality was 121.0 +/- 5.1 and 123.5 +/- 3.2 and was not different from the TNZ-acclimated cattle. Heat production of steers acclimated to different temperatures was variable during the 3- and 24-h exposures to test-temperatures ranging from 25 to 40 C. Heat production increased linearly in the TNZ-acclimated cattle (24-h exposure) and in the heat-acclimated cattle (3-h exposure) at the rate of 1.3 and 2.3 kcal X kg-75 X d-1 X C-1 increase in test-temperature, respectively. In the other four comparisons, analysis by regression indicated no significant change in heat production. Rectal temperature and respiration rate increased significantly in either a linear or quadratic manner in all treatment groups exposed to test-temperatures from 25 to 40 C.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1986

Fearful and associated responses of White Leghorn hens: effects of cage environments and genetic stocks.

Three measures of fearfulness were evaluated for hens of four genetic stocks after they had been kept in single-, 4-, and 6-bird cages for 26 or more weeks. Twelve hens of each stock and cage-environment combination were used (a total of 144 birds). Two tests involved latency of hungry hens to feed when confronted with fear-stimulating objects and one test was for latency to recover from induced tonic immobility. Results for the genetic stocks were inconsistent; strains identified as more fearful by a particular criterion were in some cases less fearful by another or did not differ. Hens kept in single-bird cages were either less fearful or showed a nonsignificant tendency, suggesting less fearfulness by all three criteria. Hens kept in 4-bird cages were typically similar in fearfulness to those in 6-bird cages. Fear-related responses were not clearly associated with plasma corticosteroids, body weights, mortality, or number of eggs laid. However, feather loss (in one test) was associated with escape and avoidance behavior of groups; stepwise increases in fearfulness with increasing group size were associated with similar increases in loss of feathers.

Animals↗
PubMedDate not supplied

Methodologic issues.

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Data Collection↗