Biomedical subjects

H M Edwards

Publications and source records attributed to H M Edwards.

At least 19 recordsLinked to original sources

PubMed1995

The folic acid requirements of starting broiler chicks fed diets based on practical ingredients. 2. Interrelationships with dietary methionine.

Two experiments were conducted to determine the effects of dietary supplemental folic acid and methionine on the performance of starting broiler chicks for 18 d. Four levels of dietary folic acid (.24, .54, 1.14, and 2.34 mg/kg) and four levels of dietary methionine (.45, .53, .61, and .69%) were fed in a factorial design. There were three replicates of eight chicks each per each treatment. The basal diet was based on corn, isolated soybean protein, meat and bone meal, and fish meal. It contained adequate amounts of all nutrients except methionine and folic acid. Increased growth was observed in chicks fed the basal diet supplemented with either folic acid or methionine. Total dietary folic acid and methionine plus cysteine requirements for maximum growth were estimated to be 1.80 mg/kg and .85% in Experiment 1 and 1.47 mg/kg and .87% in Experiment 2, respectively. There were interactions between dietary folic acid and methionine on weight gain in both experiments. Chicks fed the diet containing 2.34 mg folic acid/kg tended to have depressed growth, as in previous experiments. There was a significant linear feed conversion response to folic acid in Experiment 1 and to methionine in Experiment 2. There were both linear and quadratic liver folic acid responses to dietary folic acid in both experiments. There was no indication that dietary methionine had any effect on liver folic acid content. No differences in bone ash, hemoglobin, hematocrit, or incidence of tibial dyschondroplasia were detected due to methionine or folic acid supplementation.

Animals↗

PubMed1995

Effects of dietary calcium and 1,25-dihydroxycholecalciferol on the development of tibial dyschondroplasia in broilers during the starter and grower periods.

Two experiments were conducted to determine whether dietary 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] can prevent tibial dyschondroplasia in broiler chickens throughout the growing period when withdrawn from the grower diet. The birds were reared in floor pens with pine shavings to 6 wk in Experiment 1 and 5 wk of age in Experiment 2. Calcium was fed at .65 or 1.00% and 1,25-(OH)2D3 was fed at 0 or 5 micrograms/kg to 3 wk of age. Half the birds consuming 1,25-(OH)2D3 were then fed 0 microgram/kg until the end of the experiments. The higher level of calcium decreased the incidences of tibial dyschondroplasia and severe lesions and increased bone ash. Dietary 1,25-(OH)2D3 increased bone ash at both levels of calcium at 3 wk and the end of the experiments when supplemented for the duration of the studies. When 1,25-(OH)2D3 was fed, tibial dyschondroplasia was reduced in Experiment 2 only at 3 wk. Tibial dyschondroplasia was decreased at 5 wk in Experiment 2 when .65% calcium was fed with or without 1,25-(OH)2D3 from 3 to 5 wk of age. There were no treatment effects on plasma calcium, dialyzable phosphorus, or 25-hydroxycholecalciferol. Plasma 1,25-(OH)2D3 was decreased at 3 and 5 wk in Experiment 2 when 1.00% calcium was fed. The results of Experiment 2 suggest that 1,25-(OH)2D3 can prevent tibial dyschondroplasia caused by inadequate calcium when fed for only 3 wk. The bone ash observed when 1.00% dietary calcium is fed is equal to that obtained when 5 micrograms/kg 1,25-(OH)2D3 is fed with .65% calcium for the entire growout period.

Age Factors↗

PubMed1994

Effects of ascorbic acid and 1,25-dihydroxycholecalciferol on alkaline phosphatase and tibial dyschondroplasia in broiler chickens.

1. The effects of graded amounts of dietary ascorbic acid with or without 10 micrograms/kg dietary 1,25-dihydroxycholecalciferol on performance, blood and bone variables were measured in broiler chicks. 2. 1,25-Dihydroxycholecalciferol prevented the tibial dyschondroplasia and rickets caused by feeding a low calcium diet. Gain:food was decreased, but body weight was not affected by feeding 10 micrograms/kg 1,25-dihydroxycholecalciferol. Phytate phosphorus retention was increased by dietary 1,25-dihydroxycholecalciferol. 3. Dietary ascorbic acid did not influence the incidence of tibial dyschondroplasia, but did reduce the incidence of rickets at a dietary concentration of 250 mg/kg. Gain:food was increased when 250 or 500 mg ascorbic acid/kg diet were added along with 10 micrograms/kg 1,25-dihydroxycholecalciferol in one of two experiments. 4. Alkaline phosphatase activity and plasma 1,25-dihydroxycholecalciferol were not affected by the dietary treatments. Plasma 25-hydroxycholecalciferol concentration was decreased by dietary 1,25-dihydroxycholecalciferol. 5. Ascorbic acid had no synergistic effects with 1,25-dihydroxycholecalciferol on the blood and bone variables investigated in broiler chickens at the dietary concentrations of 1,25-dihydroxycholecalciferol used in this work.

Alkaline Phosphatase↗

PubMed1994

Quantitative requirement for cholecalciferol in the absence of ultraviolet light.

Studies were conducted to determine the basic requirement of the bird for cholecalciferol in the absence of ultraviolet light by utilizing filter sleeves on fluorescent lights in the room and brooder. In Experiment 1, some pens were fitted with filter tubes and some lights were turned off. All the birds received a cholecalciferol-deficient diet. Birds with ultraviolet light excluded grew slowly, developed rickets (95%), had low plasma calcium, and low bone ash (27%); whereas birds exposed to the fluorescent light had normal growth and plasma calcium, slightly low bone ash (38%), and some rickets (12%). Experiments 2 and 3 were conducted to determine the amount of cholecalciferol that must be added to the diet under conditions in which ultraviolet light was excluded. In Experiment 2, the highest level of cholecalciferol fed was 400 ICU/kg. This level was not sufficient to permit the chickens to have weight gain or bone ash equal to the birds receiving the ultraviolet light. The birds receiving 400 ICU/kg of diet also had a 77% incidence of rickets compared with 20% for the birds receiving ultraviolet lights. In Experiment 3, when birds received 800 or 1,600 ICU/kg of cholecalciferol in the diet, they grew and were comparable to those receiving ultraviolet light for the criteria measured.

Animals↗

PubMed1994

Effect of early castration on body weight, muscle growth, and bone characteristics of male Nicholas strain turkeys.

Body weight of male Nicholas strain turkeys, castrated at 8 to 10 d of age, averaged .60, 2.20, 5.26, 8.26, and 10.83 kg at 3, 6, 9, 12, and 15 wk of age, respectively. These weights did not differ significantly from those of sham-operated control birds, but were significantly less than those of unoperated controls at 12 and 15 wk of age. Pectoralis major weights of 15-wk-old castrated turkeys were not significantly different than the sham-operated controls, but were less than those of intact controls. Pectoralis weights, expressed as a percentage of BW, did not differ among these groups. There were no differences in tarsometatarsal lengths, weight, or percentage ash among the groups. The incidence of tibial dyschondroplasia ranged from 66.7 to 80.0%, with average scores ranging from 1.00 to 1.42, with no differences among groups. Plasma testosterone concentrations of unoperated and sham-operated controls averaged .16 and .26 ng/mL at 15 wk, whereas concentrations in 7 of 12 castrates were undetectable and amounts in the other 5 castrates averaged .03 ng/mL.

Animals↗

PubMed1994

Effect of genetic strain, calcium, and feed withdrawal on growth, tibial dyschondroplasia, plasma 1,25-dihydroxycholecalciferol, and plasma 25-hydroxycholecalciferol in sixteen-day-old chickens.

Four experiments were conducted to study the effects of genetic strain, dietary Ca level, and feed withdrawal on growth, feed efficiency, tibia bone ash, tibial dyschondroplasia (TD), and plasma 1,25-dihydroxycholecalciferol [1,25(OH)2D3] and 25-hydroxycholecalciferol [25(OH)D3]. Experiment 1 used five strains and Experiments 2 to 4 used three broiler strains. A TD-inducing basal diet was used in each experiment. In Experiment 3, the birds were fed .60 or .95% dietary Ca, and in Experiment 4 the birds were fed the basal diet and were fed or deprived of feed for 8 h daily. In Experiment 1, Athens-Canadian Randombred and Single Comb White Leghorn chicks did not develop TD. In birds fed the basal diet alone, Peterson x Hubbard chicks had a significantly higher incidence of the most severe TD lesion than two other broiler strains in each experiment and were significantly lighter in BW in two of the four experiments. Of the three broiler strains, the incidence and average lesion score of TD was significantly higher in Peterson x Hubbard birds in Experiment 2 and was numerically highest in the other three experiments. In birds fed the basal diet, Peterson x Hubbard birds had significantly higher plasma 1,25(OH)2D3 in two of the four experiments. Both feed deprivation and .95% Ca increased bone ash and decreased the incidence and severity of TD. There were no significant differences in plasma 1,25(OH)2D3 among strains of birds deprived of feed or fed .95% Ca. In three of the four experiments, high plasma 1,25(OH)2D3 in Peterson x Hubbard birds was associated with an increase in the incidence and severity of TD.

Animals↗

PubMed1994

Effects of 1,25-dihydroxycholecalciferol and phytase on zinc utilization in broiler chicks.

Studies were conducted with corn-soybean meal diets to evaluate the effects of phytate phosphorus utilization on zinc absorption and retention in broiler chicks. In the first two experiments, zinc-65 was used to determine zinc absorption. Experiment 1 was a 2 x 2 factorial with 0 or 5 micrograms/kg dihydroxycholecalciferol and 0 or 40 ppm supplemental zinc. In Experiment 2, 5 micrograms/kg 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] or 750 units/kg phytase or both were added to a diet containing 35 ppm zinc. The diets in Experiment 3 were similar to Experiment 2 except that 600 units/kg phytase was fed. Experiment 4 was similar to Experiment 3 except that dietary phosphorus was decreased by .15%. There were no treatment effects on body weight in Experiments 1 and 2. Zinc absorption was higher in zinc-deficient birds in Experiment 1, but there were no other effects on zinc-65 absorption or retention. Body weight was increased by 1,25-(OH)2D3 in Experiments 3 and 4 and by phytase in Experiment 4. Phytate phosphorus retention was increased by phytase and 1,25-(OH)2D3 and was increased additively when both sources were fed. Dietary 1,25-(OH)2D3 increased zinc retention at times during Experiments 3 and 4, but this response was inconsistent. Phytase did not affect zinc retention. Phytase plus 1,25-(OH)2D3 increased zinc retention synergistically in Experiment 3. Bone zinc was increased by 1,25-(OH)2D3 and phytase, and there was an additive effect in Experiment 3. Plasma zinc and alkaline phosphatase were not affected. The results suggest that supplemental zinc may be decreased in a corn-soybean meal diet when phytate phosphorus utilization is enhanced.

6-Phytase↗

PubMed1993

Dietary 1,25-dihydroxycholecalciferol supplementation increases natural phytate phosphorus utilization in chickens.

These studies were conducted to determine if supplementation of a corn-soybean meal diet with 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] would increase the utilization of natural phytate phosphorus by broiler chickens. Two experiments were conducted to evaluate the effect of dietary 1,25-(OH)2D3 in the presence and absence of supplemental phytase and at several dietary levels of inorganic phosphorus supplementation. The criteria measured in these studies were weight gain, gain:feed ratio, bone ash, rickets due to phosphorus deficiency, plasma calcium and phosphorus and retention of calcium, phosphorus and phytate phosphorus. In the first experiment, the types and amounts of fecal inositol phosphates were determined by HPLC, and the total fecal phytate was determined by the classic FeCl3 precipitation technique. In the first experiment, the addition of 1,25-(OH)2D3 to the diet in the presence of dietary phytase resulted in greater 9-d weight and bone ash and lower incidence of rickets; the retention of total fecal phytate and phytate phosphorus was greater than in controls. The second experiment was a complete 2 x 2 x 2 factorial design [phosphorus levels x phytase x 1,25-(OH)2D3]. The addition of 1,25-(OH)2D3 alone to the diet resulted in greater 9-d weight and bone ash, lower incidence of rickets, and greater retention of total calcium and phosphorus and phytate phosphorus. The highest retention of phytate phosphorus (79.4%) was obtained when both phytase and 1,25-(OH)2D3 were present in the diet. The possible mode of action and importance of these results in many areas of nutrition and environmental science are discussed.

6-Phytase↗

PubMed1992

Calcium and phosphorus requirements of the very young turkey as determined by response surface analysis.

The first experiment was a central composite rotatable design with calculated calcium levels of 6.2, 7.0, 9.0, 11.0, and 11.8 g/kg diet and total phosphorus levels of 5.2, 6.0, 8.0, 10.0, and 10.8 g/kg diet (2.8 g phytin-P/kg by analysis). This design involved three replicates for each rotatable point and fifteen replicates of the central point. The second experiment was a 4 x 4 factorial design with calculated Ca levels of 8.0, 10.0, 12.0, and 14.0 g/kg diet and calculated total P levels of 7.0, 9.0, 11.0, and 13.0 g/kg diet (2.5 g phytin-P/kg by analysis). There were four replicates for each treatment. In both 16 d experiments maize-soya-bean diets were used and each replicate consisted of one pen containing 10-d-old broad-breasted, white tom turkeys. The Ca and total P requirements for optimum growth were estimated to be 12.5 and 10.0 g/kg diet respectively. Bone ash was adequate at these levels of Ca and total P, but maximum bone ash was not achieved until much higher levels of Ca and total P were employed. At the required levels of Ca and total P for growth the incidences of Ca- and P-deficiency rickets were very low. There were no treatment effects on feed efficiency. Increasing dietary Ca decreased the incidence of the Ca-deficiency lesion. There was a quadratic response due to dietary total P on both P-deficiency rickets and plasma dialysable P; intermediate levels of dietary P resulted in low incidence of the P-deficiency lesion and high levels of plasma dialysable P. There was a strong negative correlation between the incidence of P-deficiency rickets and plasma dialysable P. Percentage retention was very low at high levels of dietary P and low levels of Ca which corresponded with slightly higher P-deficiency rickets and low plasma dialysable P. No such obvious relationships existed between Ca retention, incidence of Ca-deficiency rickets, and plasma Ca. The incidence of tibial dyschondroplasia was very low in the present study. There were pronounced dietary treatment effects on phytin-P retention; at 14 d percentage phytin-P retention treatment means ranged from 18 to 46 in Expt 1 and from 0 to 40 in Expt 2 with the highest retention of phytin-P at low levels at both Ca and total P.

Animals↗

PubMed1992

Studies to determine whether an interaction exists among boron, calcium, and cholecalciferol on the skeletal development of broiler chickens.

Two experiments were designed to determine the effect of dietary boron on broiler cockerels and four experiments were conducted to determine whether an interaction exists among dietary boron, cholecalciferol, and calcium. The parameters measured were weight gain, feed efficiency, tibia bone ash, rickets, tibial dyschondroplasia, and plasma minerals. All experiments were conducted with tibial dyschondroplasia-inducing basal diets fed to broiler cockerels from 1 to 16 days of age. Experiments 1 and 2 had four levels of dietary boron (0, 20, 40, and 80 mg/kg (Experiment 1) and 0, 5, 10, and 20 mg/kg (Experiment 2). Boron had no effect on weight gain, feed efficiency, or plasma minerals in either experiment. In Experiment 2, increasing levels of boron had no influence on tibial dyschondroplasia but did exert a quadratic effect on bone ash with 5 and 10 mg/kg boron increasing bone ash. In Experiment 1, bone ash and the incidence of tibial dyschondroplasia were unaffected, but the severity of tibial dyschondroplasia linearly increased by increasing boron levels. Experiments 3 to 6 had a 2 x 2 x 2 factorial arrangement of treatments with calcium at .65 and .90%, cholecalciferol at 110 and 1,100 ICU/kg, and boron at 0 and 40 mg/kg (Experiments 3 to 5) or 0 and 3 mg/kg (Experiment 6). The higher levels of calcium and cholecalciferol improved weight gain, decreased the incidence of rickets, and decreased the incidence and severity of tibial dyschondroplasia. Feeding cholecalciferol at 1,100 ICU/kg increased plasma calcium and plasma dialyzable phosphorus and decreased plasma magnesium. Calcium at .90% had no effect on plasma magnesium or plasma dialyzable phosphorus and increased plasma calcium only in Experiment 4. The only response to boron in Experiments 3 to 6 was a boron effect and a boron by cholecalciferol interaction on bone ash in Experiment 3, in which boron reduced bone ash at .65% calcium and 110 ICU/kg cholecalciferol. From these experiments, there is no indication that an interaction among boron, cholecalciferol, and calcium exists in broiler cockerels.

Animal Feed↗

PubMed1992

Effect of dietary calcium on tibial dyschondroplasia. Interaction with light, cholecalciferol, 1,25-dihydroxycholecalciferol, protein, and synthetic zeolite.

A series of experiments was conducted to investigate interactions of dietary calcium levels with ultraviolet light, cholecalciferol (D3), 1,25-dihydroxycholecalciferol [1,25-(OH)2D3], dietary protein, and a synthetic zeolite on the development of tibial dyschondroplasia in broilers. A basal diet low in calcium, high in phosphorus and chloride, and known to promote a high incidence of tibial dyschondroplasia was used. The chicks received ultraviolet radiation from fluorescent lights in addition to 1,100 ICU/kg (27.5 micrograms/kg) of D3 in the basal diet when these were not experimental variables. Regardless of whether the calcium level was low (.65%) or adequate (.95%), the incidence of tibial dyschondroplasia was significantly lower in chicks receiving ultraviolet radiation or dietary vitamin D3 levels well above the required amounts. The addition of 10 micrograms/kg of 1,25-(OH)2D3 to the diet when calcium levels varied from .45 to .95% resulted in a reduction in the incidence of tibial dyschondroplasia and increased tibial bone ash when dietary protein levels were 18 or 22%. The addition of 1% synthetic zeolite to the diet did not influence the incidence of tibial dyschondroplasia when the diet contained widely varying dietary calcium levels (.65 to 1.81%) and .73% phosphorus.

Aluminum Silicates↗

PubMed1991

Effect of dietary silicon on growth and skeletal development in chickens.

Experiments were conducted to determine the effect of supplementary dietary silicon on weight gain, feed efficiency, percent tibia bone ash and on the development of tibial dyschondroplasia in broiler chickens. Experiments 1 and 2 were conducted with casein/gelatin-based purified diets and Experiments 3 and 4 with corn/soy-based practical diets. All experiments used day-old broiler cockerels and lasted 16 d. Silicon supplementation (250 mg/kg) significantly decreased growth rate and the incidence and severity of tibial dyschondroplasia in Experiment 1 and had no effect on either parameter in Experiments 2-4. Dietary silicon supplementation significantly reduced feed efficiency in Experiments 1 and 3. Tibia bone ash was unaffected by dietary silicon supplementation in any of the experiments conducted. The results of the present studies indicate that dietary silicon supplementation has no effect on growth and skeletal development in broiler chickens.

Analysis of Variance↗

PubMed1991

The effects of 1,25-dihydroxycholecalciferol on performance and bone development in the turkey poult.

The effect was studied of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] at various levels of vitamin D3, with adequate or inadequate dietary calcium, on performance and bone development in turkey poults. Two experiments were conducted. Experiment 1 lasted 16 days and was a 4 x 2 factorial arrangement using a low calcium diet (.7%), with dietary levels of vitamin D3 of 450, 900, 1,800, and 3,600 ICU/kg of diet and with or without 10 micrograms of dietary 1,25-(OH)2D3. Experiment 2 lasted 14 wk and was a 2 x 2 x 2 factorial arrangement with vitamin D3 levels of 900 or 2,700 ICU/kg of diet, calcium levels at 58 or 100% of the National Research Council requirement (which varies with age), and with or without 10 micrograms/kg of dietary 1,25-(OH)2D3. In Experiment 1, increasing levels of vitamin D3 and 1,25-(OH)2D3 supplementation significantly increased bone ash. Pairwise contrasts at specific vitamin D3 levels indicated that this effect of 1,25-(OH)2D3 was greater at lower levels of vitamin D3. In Experiment 2, the 2,700-ICU level of vitamin D3 decreased the incidence of rickets at 3 wk and partially ameliorated a calcium deficiency, as indicated by an increase in growth at the 2,700-ICU level of vitamin D3 in calcium-deficient diets from 8 to 14 wk. Vitamin D3 by calcium interactions on rickets at 14 wk of age and bone ash at 3 and 14 wk were similar and indicated also that vitamin D3 partially ameliorated a calcium deficiency. In general, the addition to the diet of 1,25-(OH)2D3 increased bone ash and decreased the incidence of rickets in diets deficient in calcium but high in vitamin D3. There is very little evidence in the present study that indicates that 1,25-(OH)2D3 has any effect on tibial dyschondroplasia.

Animals↗

PubMed1991

Some effects of dietary aluminum and silicon on broiler chickens.

Experiments were conducted to determine whether dietary silicon will reduce the toxic effects of dietary aluminum on broiler chickens. The parameters measured were weight gain, feed efficiency, percentage bone ash, tibial dyschondroplasia, and the retention of calcium, phosphorus, and phytin phosphorus. Experiments 1 and 2 were conducted with casein and gelatin-based purified diets and Experiments 3 and 4 with corn and soybean meal-based practical diets. All experiments used day-old broiler cockerels and lasted 16 days. Aluminum significantly reduced weight gain, feed efficiency, and percentage bone ash in all four experiments. Aluminum supplementation reduced the incidence and severity of tibial dyschondroplasia, but this effect was associated with a reduction in weight gain. Increasing dietary aluminum reduced the retention of phosphorus and phytin phosphorus. Silicon did not alleviate the effects of aluminum toxicity on any of the parameters measured but did independently increase growth rate in Experiments 1 and 2, Supplementary dietary silicon does not appear to reduce aluminum toxicity in broiler chickens. Aluminum appears to exert its toxic effect on chickens by reducing the retention of phosphorus and phytin phosphorus.

Aluminum↗

PubMed1991

Comparison of the effects of synthetic and natural zeolite on laying hen and broiler chicken performance.

Three experiments were conducted to investigate the effect of zeolites on laying hens (Experiments 1 and 2) and broiler chickens (Experiment 3). Each experiment used corn and soybean meal-based practical diets. Experiment 1 was a 90-day trial and used 200 40-wk-old laying hens. The basal diet contained 2.75% calcium and .7% total phosphorus. The dietary treatments were the basal diet and the basal diet plus 1.5% synthetic zeolite (SZ; Ethacal). Experiment 2 was a 56-day trial and used 360 36-wk-old laying hens. The dietary treatments were .12, .22, .32, and .42% nonphytin phosphorus with and without 1.0% SZ and 1.0% natural zeolite (NZ; Zar-Min). All diets contained 3.5% calcium. Experiment 3 utilized 240 broiler cockerels from 1 to 16 days. The dietary treatments were two calcium levels (.65 and 1.0%) with and without 1.0% supplementary SZ and NZ. In Experiment 1, egg specific gravity was significantly increased with SZ supplementation. Egg weight and egg production were unaffected. Phytin phosphorus retention and plasma dialyzable phosphorus were significantly reduced by SZ. In Experiment 2, egg specific gravity was not affected by SZ or NZ. Egg weight, egg production, plasma dialyzable phosphorus, and the retention of phosphorus and phytin phosphorus were significantly reduced by SZ with the effect on egg weight and egg production being the most severe at the lower levels of dietary nonphytin phosphorus. Natural zeolite had no effect on egg weight, egg production, plasma calcium, plasma phosphorus, or on the retention of calcium, phosphorus, and phytin phosphorus. In Experiment 3, weight gain and percentage tibia bone ash were significantly reduced by SZ. The SZ had no effect on the incidence and severity of tibial dyschondroplasia. Weight gain, feed efficiency, and the incidence and severity of tibial dyschondroplasia were significantly reduced and the percentage bone ash significantly increased by 1.0% calcium. Natural zeolite significantly improved feed efficiency and had no effect on any other parameter measured.

Aluminum Silicates↗

PubMed1990

Essential fatty acid nutrition of the American alligator (Alligator mississippiensis).

The essential fatty acid (EFA) nutrition of young American alligators (Alligator mississippiensis) was examined by feeding a variety of fats/oils with potential EFA activity. Over a 12-wk period, alligators fed diets containing 2.5 or 5.0% chicken liver oil grew longer and heavier and converted feed to body mass more efficiently than alligators fed other fat/oil combinations that lacked or contained only trace amounts of arachidonic acid [20:4(n-6)]. Alligators fed an EFA-deficient diet (containing only coconut fat as the dietary fat) were the slowest-growing animals and converted feed to body mass least efficiently. However, over a 41-wk feeding period, alligators fed this diet showed no obvious external signs of deficiency other than being reduced in size and unthrifty. Fatty acid composition of heart, liver, muscle, skin and adipose tissue lipids was influenced markedly by dietary fat composition. Tissues varied significantly in response to dietary fat composition. Heart lipids contained the lowest levels of short- and medium-chain fatty acids and the highest levels of arachidonic acid. Arachidonic acid levels were less influenced by diet than were levels of other 20- and 22-carbon polyunsaturated fatty acids. Radiotracer studies indicated that linoleic acid was converted to arachidonic acid in the liver. Nevertheless, tissue arachidonic acid levels also appeared to be maintained by concentration from dietary sources and selective conservation. It appears that a dietary source of arachidonic acid may be required for a maximum rate of growth.

Adipose Tissue↗

PubMed1990

Protein and energy relationships in the diet of the American alligator (Alligator mississippiensis).

First-year alligators (Alligator mississippiensis) averaging 377-857 g body weight were fed diets containing various levels of protein, fat and carbohydrate. In experiment 1, nine diets arranged in a centrally rotatable composite design contained 0-36% extruded corn and 4-20% total fat. Response surface analysis predicted maximum responses in performance criteria at 6.3-18.8% corn and 15.8-27.4% fat. Corn inclusion at up to 27-36% of diet resulted in equal or improved performance compared to carbohydrate-free diets of equal fat content. Energy digestibility averaged 84.3%. Protein digestibility averaged 86.7%. Maximum responses in performance criteria were predicted at 42.5-48.7% digestible protein and 4367-4421 kcal/kg digestible energy. In two additional experiments, alligators were either fasted or fed for various numbers of days/week. Carbohydrate-supplementation of high protein diets led to equal or significantly improved performances. Performance was maximized by feeding the alligators 5-6 d/w. Regression of body weight changes against energy and protein intake yielded estimates of daily maintenance requirements of 5.7-8.4 kcal and 0.49-0.89 g protein/kg live body weight. Dietary fat and carbohydrate in the forms and amounts fed to young alligators were well-utilized. Optimal digestible energy:crude protein ratios (8.2-10.9:1 kcal/g protein) were similar to those of other aquatic ectotherms of equal size.

Alligators and Crocodiles↗

PubMed1990

Efficacy of several vitamin D compounds in the prevention of tibial dyschondroplasia in broiler chickens.

Studies were conducted to evaluate several cholecalciferol (D3 metabolites: 1,25-dihydroxycholecalciferol [1,25-(OH)2D3], 1,24R,25-trihydroxycholecalciferol [1,24R,25-(OH)3D3], 1 alpha-hydroxy-cholecalciferol (1 alpha-OHD3), 24R,25-dihydroxycholecalciferol [24R,25-(OH)2D3], 1,25-dihydroxy-26,27 hexadeuterium cholecalciferol (1,25-(OH)2-26,27[2H]6D3) and 1,25-dihydroxy-24R-fluorocholecalciferol [1,25-(OH)2-24R-FD3] for their activity in preventing the development of tibial dyschondroplasia in broilers. The basal diet used is low in calcium, high in phosphorus and chlorine and is known to promote a high incidence of tibial dyschondroplasia. The chicks received ultraviolet radiation from fluorescent lights in addition to 1100 ICU/kg (27.5 micrograms/kg) of D3 in the basal diet. Supplementation of the diet with 10 micrograms/kg of all the metabolites except 24R,25-(OH)2D3 significantly lowered the incidence and severity of tibial dyschondroplasia and increased bone ash when compared to birds receiving the basal diet. None of the active D3 metabolites was effective when fed at 0.1 or 1.0 micrograms/kg of diet. Two active compounds tested [1,25-(OH)2D3 and 1,24R,25-(OH)3D3] at 5 micrograms/kg of diet were effective in reducing either the incidence or severity of tibial dyschondroplasia.

24,25-Dihydroxyvitamin D 3↗