Biomedical subjects

L J Caston

Publications and source records attributed to L J Caston.

9 recordsLinked to original sources

PubMed1998

Nuclear magnetic resonance imaging as a tool to estimate the mass of the Pectoralis muscle of chickens in vivo.

1. Nuclear magnetic resonance imaging (MRI) was used to assess the advantages of the technique in determining the size (volume) and shape of the Pectoralis muscle (Pectoralis major and minor) in broiler chickens, non-invasively and in vivo. 2. The imaging was performed using a Spectroscopy Imaging System 2.0 Tesla/31 cm bore imaging spectrometer. Three-dimensional reconstruction of transverse images was used to estimate the size of the Pectoralis muscle of chickens ranging in body weight from 362 to 1643 g. 3. Regression analysis resulted in R2 values of 0.92 and 0.99 for the relationship between Pectoralis muscle weight, body weight and muscle volume, respectively. 4. It is concluded that MRI and 3-dimensional image reconstruction may be used to estimate the Pectoralis muscle size and shape. This may be readily extended to monitor the influence of various factors on the growth and development of specific organs and tissues in the body.

Animals↗

PubMed1997

A problem with characteristics of the thin albumen in laying hens.

Industry observations indicate that a proportion of shell eggs exhibit an uncharacteristic spreading of the thin albumen when they are broken-out for fast-food preparation. Because the height and characteristics of the thick albumen are unaffected, the eggs are classified as Grade A. Preliminary observations discounted effects of egg storage or contaminated feed. Two experiments were conducted with Leghorn hens over a full laying cycle, and involved different levels of protein (14, 16, 18, or 20%) and associated amino acids, or different degrees of acid-base balance (150, 200, 250, or 300 mEq/kg). In each trial, treatments were represented by eight replicate groups of four adjacently and individually caged birds. Diet treatment had some effects on conventional production parameters, although there were no major effects on the area of the thin albumen produced when eggs were broken out. In Experiment 1, birds fed the highest level of protein produced eggs with the smallest thin albumen area; however, there was considerable bird to bird variation with thin albumen area varying from 69 to 122 cm2. Ten birds with compact (x 69 cm2) and 10 birds with spreading thin albumen (x 112 cm2) were inseminated with semen from a single, unrelated rooster. Offspring from these hens had significantly (P < 0.01) different thin albumen characteristics corresponding to those of their dams. Offspring producing eggs with the spreading thin albumen had the thickest eggshells as assessed by deformation measurement (P < 0.05). It is proposed that the excessively large spreading thin albumen area is caused by eggs spending more time in the shell gland.

Acid-Base Equilibrium↗

PubMed1995

alpha-Linolenic acid- and docosahexaenoic acid-enriched eggs from hens fed flaxseed: influence on blood lipids and platelet phospholipid fatty acids in humans.

This study was undertaken to examine the effects that consumption of eggs from hens fed diets containing flaxseed would have on plasma and platelet lipids of male volunteers. Feeding diets containing 0%, 10%, and 20% ground flaxseed to Leghorn pullets provided a marked progressive increase in n-3 fatty acid content as alpha-linolenic acid (alpha-LNA) (28, 261, and 527 mg/egg) and docosahexaenoic acid (DHA) (51, 81, and 87 mg/egg) but no alteration in the cholesterol concentration of the egg yolk. Twenty-eight male volunteers, divided into three groups, were fed four eggs per day for 2 wk according to a cyclic Latin-square design. No statistically significant changes were observed in total cholesterol, high-density-lipoprotein cholesterol, or plasma triglyceride concentrations. Significant increases in total n-3 fatty acids and in DHA content (which rose from 1.5 to 2.0% by wt or 33% overall), and a significant decrease in ratio of n-6 to n-3 fatty acids were found in platelet phospholipids of subjects consuming eggs from flaxseed-fed hens. Health and Welfare Canada in 1990 set recommended intakes for dietary n-3 fatty acids and for the ratio of n-6 to n-3 fatty acids, which are not being met currently by the overall population. Eggs modified by the inclusion of flaxseed in the laying hens' diet could provide an important nutritional source of n-3 fatty acid.

Adult↗

PubMed1992

Response of broilers to feed restriction or diet dilution in the finisher period.

Two experiments were conducted to study the response of 35- to 49-day-old male broilers to either feed restriction or diet dilution. In Experiment 1, after being fed conventional starter-grower diets to 35 days of age, birds consumed either a conventional finisher diet ad libitum, or 10, 20, 30, 40, or 50% less of this diet to 49 days of age. Performance and carcass characteristics were measured from 35 to 42 days and 42 to 49 days. There was a linear relationship between nutrient intake and 42- and 49-day body weight (P < .01). However, as a percentage of the control birds, weight gain was reduced less from 42 to 49 days (64%) than from 35 to 42 days (86%) for the 50% restricted group. Thus, there was apparently an adaptation in the period from 42 to 49 days. In a second comparable experiment, birds were offered a conventional finisher diet or one with either 10, 20, 30, 40, or 50% dilution with a 50:50 (wt:wt) mixture of sand:oat hulls. Growth rate was only slightly reduced, thus demonstrating the remarkable ability of the broilers at this age to increase feed intake in response to energy density of the diet. Although birds were of comparable weight, diet dilution resulted in a linear reduction in size of abdominal fat pad, whereas breast weight was not affected. The present data suggest that broiler chickens are far from eating to physical capacity, at 35 days of age, because they were able to exhibit up to a 70% increase in feed intake relative to the control birds.

Aging↗

PubMed1992

The effect of dietary sodium on right ventricular failure-induced ascites, gain and fat deposition in meat-type chickens.

Experiments were carried out using various levels of sodium (Na+) from NaCl or NaHCO3 to determine: 1) the level of Na+ required to induce ascites alone or in combination with cold temperature and 2) the effect of Na+ on weight gain and fat deposition in broiler chickens. In experiment 1, there were no cases of ascites using levels of Na+, from NaCl at 0.14% to 0.44% in the feed from day 3 or using added Na+, from NaCl at 0.0% to 0.12% in the water from day 3 with a level of 0.14% in the feed. There was no significant difference in 21 or 42 day body weight, feed conversion, or right ventricle:total ventricle (RV:TV) ratio between treatment groups. Day 3 to 4 body weight gains were significantly increased in all treatment groups with added Na+ (p less than 0.01). In experiment 2, with levels of added Na+, from NaCl, at 0.0% to 0.12% in the water with a level of 0.20% in the feed there were two cases of ascites, one at day 7 and one at day 40 at the 0.12% level. There were no significant differences in body weight at days 21 or 42 or in the RV:TV ratios between groups. Feed conversions were improved (p less than 0.01) with the lowest and highest levels of Na+ and a significant increase in day 3 to 4 body weight gain, with increasing Na+ in all treatment groups, was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1991

Diet dilution and compensatory growth in broilers.

Two experiments were conducted to note the response of broiler chickens to degrees of diet dilution from 4 to 11 days of age. In Experiment 1, broilers were fed conventional broiler diets from 0 to 4 and 11 to 56 days of age. From 4 to 11 days, birds were fed a conventional corn and soybean meal broiler starter, or the same diet in which major nutrients were replaced with 25, 40, or 55% ground rice hulls. Mineral and vitamin sources were not affected by dilution. Each of the three diluted diets together with an undiluted control diet was fed to three replicate floor pen groups of 30 male or 30 female broilers. In a second similar experiment, male birds were fed a regular broiler starter from 4 to 11 days or a diet diluted with 50% rice hulls. In this second experiment, rice hulls were substituted for all ingredients including those providing vitamin and mineral supplements. In Experiment 1, diet dilution resulted in a significant (P less than .05) reduction in body weight at 11 days of age, although by 42 days there was complete recovery of body weight with no change in overall efficiency of feed utilization. This same trend was seen in both sexes. Calculation of energy balance suggests these birds to have used energy very efficiently during the period of undernutrition. Diet dilution had no effect on carcass characteristics at 42 days, although for males at 56 days there was an indication of reduced abdominal fat content (P less than .05). In Experiment 2, compensatory gain was incomplete, although results were confounded due to an outbreak of infectious bronchitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗

PubMed1991

Response of laying hens to supplemental niacin.

Two experiments were conducted to investigate the effect of supplemental niacin on laying hen performance and liver fat and egg cholesterol content. In Experiment 1, 16 replicate groups of four adjacently caged birds were fed corn and soybean meal diets calculated to contain 22, 44, 66, or 132 mg supplemental niacin/kg (23.2, 38.7, 57.0, and 143 mg/kg niacin by analysis). Egg production, egg weight, feed intake, and eggshell quality were assessed each 28 days through a 364-day trial period. After 280 days, cholesterol content on three eggs per replicate was measured. At the end of the study, one bird per replicate was killed for subjective scoring of liver fat content. In Experiment 2, 24 birds from the control treatment (22 mg/kg supplemental niacin) of Experiment 1 were retained and fed for a subsequent 28-day period. Over this time, eight birds were each fed diets containing 22, 522, or 1,022 mg/kg supplemental niacin. Egg cholesterol content was measured in eggs collected on the last 3 days of the study. In Experiment 1, birds fed 66 or 132 mg/kg supplemental niacin/kg produced more eggs (P less than .05) than birds fed 22mg/kg. Niacin supplementation affected shell quality (P less than .05). Dietary niacin level had no effect on egg cholesterol content of liver lipid evaluation. In Experiment 2, supplementary niacin levels up to 1,022 mg/kg, which more closely stimulates therapeutic levels used for humans, again failed to affect egg cholesterol content.

Animal Feed↗

PubMed1991

Growth and development of Leghorn pullets subjected to abrupt changes in environmental temperature and dietary energy level.

Four trials were conducted to note the response of pullets to changes in environmental temperature and energy level at 56 days of age. In each trial, birds were fed diets providing either 2,500 or 3,000 kcal ME/kg throughout rearing, or with a single diet change from 2,500 to 3,000 and 3,000 to 2,500 kcal ME/kg occurring at 56 days. Each of the four diet scenarios was tested with six replicate caged groups each containing 10 pullets. In Trials 1 and 2 environmental temperature was maintained at 18 and 30 C, respectively, to 126 days. In Trials 3 and 4, temperature was changed at 56 days from 18 to 30 C and 30 to 18 C, respectively. Regardless of environmental temperature conditions, diet change per se had minimal effect on growth and development. Rather dietary energy level used from 56 to 126 days had the greatest effect on growth, with birds fed the highest energy content diet generally being heaviest. However, this effect was not significant (P greater than .05) in all trials, which is probably related to a lack of effect on energy intake under such conditions. Final body weight was more closely associated with energy intake than with protein intake and energy intake was maximized when high-energy diets were used after 56 days of age. Consumption of high-energy diets after 56 days, regardless of trial conditions, always resulted in increased carcass fat content at 126 days. It was concluded that abrupt and major changes in environmental temperature or dietary energy as used in these trials have little deleterious effect on pullet development. Conditions prevailing during later stages of growth have a far greater effect than changes per se in these parameters.

Animal Feed↗

PubMed1988

Restricted water access time as a means of growth control in turkey tom breeder candidates.

Seventeen-wk-old turkey tom breeder candidates were allowed access to water for 4 h each day, as 2 x 2-h periods, to 21 wk. After this time, water access was reduced to 1.5 h/day (21 to 25 wk) and subsequently to 1 h/day (25 to 33 wk). Access time was reduced over time, as the earlier water access time allocation was considered excessive. With 1-h access time each day (2 x 30 min) there were no behavioral signs of thirst, and toms did not use the total time allocation for drinking. Restricted access to water reduced body weight from 25 to 33 wk of age (P less than .05). This BW reduction was accompanied by a nonsignificant reduction in feed intake. At 35 wk of age, semen weight (P less than .05) and sperm count (P less than .01) was increased for toms previously subjected to restricted water-access time. It is concluded that restriction of time that toms are allowed to drink can be used to augment other methods used in control of body weight.

Animals↗