D V Maurice’s research while affiliated with Clemson University and other places

Experiments were conducted to determine the effect of vitamin A deficiency in chicks on tissue ascorbic acid, plasma oxidant status and antioxidant capacity, and renal L-gulonolactone oxidase activity (GULO) in broiler chickens. Chicks were reared in battery cages and fed a practical diet with vitamin A (control) or the same diet without supplemental vitamin A from day-old to 23 or 30 days of age. The treatments were arranged in a randomized complete block design with 6-8 replications. At termination body weight, feed intake, and tissue weights were recorded and tissues analysed for ascorbic acid, GULO activity, antioxidant activty, and oxidant status. Growth, feed intake, relative weights of bursa of Fabricius, liver, spleen and testis were significantly reduced in vitamin A-deficient chicks. Vitamin A deficiency depressed renal GULO activity by 20016 (P<0.08) and 33% (P<0.007) in Experiment I and 2 respectively. Bursal, hepatic, splenic, testicular, and plasma ascorbic acid concentrations, plasma total antioxidant activity, and plasma oxidant status were not altered by the decrease in GULO activity. However, plasma advanced oxidation protein products were lower (P<0.02) in vitamin A-deficient chickens. The lack of effect on tissue ascorbic acid and antioxidant capacity suggest that metabolic changes associated with vitamin A deficiency may reduce ascorbic acid excretion. The reduction in plasma advanced oxidation protein products may be ascribed to lower metabolic activity because of hypothyroidism in vitamin A-deficient chicks. In conclusion, short-term vitamin A deficiency in broiler chicks reduced GULO activity without concomittant changes in tissue ascorbic acid.

1. An experiment was conducted with commercial White Leghorn type chickens to determine the effect of gender on tissue ascorbic acid concentration, antioxidant capacity and ascorbic acid synthesis. 2. Birds reared and maintained on litter were given a standard layer diet, without supplemental ascorbic acid, from 18 weeks of age. Tissue ascorbic acid concentration, plasma total antioxidant capacity and renal L-gulonolactone oxidase activity were measured at 30 weeks of age. 3. Females and males differed in ascorbic acid synthesis, as measured by renal L-gulonolactone oxidase activity, and tissue ascorbic acid concentration. 4. Plasma total antioxidant capacity and adrenal, gonadal, plasma and pituitary ascorbic acid concentrations were significantly higher in males, whereas ascorbic acid synthesis and splenic and thymic ascorbic acid concentrations were significantly higher in females. 5. L-Gulonolactone oxidase activity was not detected in the comb of cockerels.

Commercial laying hens maintained under controlled conditions were experimentally inoculated with the S6 strain of Mycoplasma gallisepticum (S6MG) at 45 wk of age. This resulted in depressed liver lipid concentration, and inoculations at 20 and 45 wk affected the size of various portions of the reproductive tract. In 2 consecutive trials of the current study, the effect of age of application of S6MG inoculation on the egg yolk characteristics of commercial layers similarly housed and maintained under controlled conditions was determined. The ages of inoculation compared were prior to lay at 10 wk of age, during onset of lay at 22 wk of age, and during postpeak lay at 45 wk of age. In each trial, yolk moisture and total lipid content were determined at 24, 32, 43, 47, and 58 wk of age. Yolk cholesterol concentration and yolk fatty acid profiles at wk 47 and 58 were also examined. Data from wk 24, 32, and 43 (effects of S6MG inoculations at 10 and 22 wk) and data from wk 47 and 58 (effects of S6MG inoculations at 10, 22, and 45 wk) were analyzed separately. The data of both trials were pooled then analyzed together. Across wk 47 and 58, percentage yolk lipid was significantly lower in eggs laid by birds inoculated at 10 wk compared with those inoculated at 45 wk. Sham-inoculated control and 22-wk inoculated groups had intermediate percentage yolk lipids. Compared with sham-control and 10-wk S6MG inoculation groups across wk 47 and 58, yolk myristic, oleic, and linolenic acid concentrations were reduced, whereas yolk stearic and arachidonic acid levels were increased by either 22- or 45-wk S6MG inoculations. In comparison with all other treatment groups at wk 47, yolk linoleic acid concentration was reduced by S6MG inoculation at 45 wk. Variable postpeak alterations in yolk total lipid and fatty acid content occur in response to the timing of S6MG inoculation in layers housed under controlled conditions.

1. An experiment was conducted with two strains of layers to ascertain whether the reduction in eggshell strength occurring at the end of the production cycle is the result of reduced ascorbic acid biosynthesis. 2. Hens producing strong and weak eggshells were identified within each strain and egg production, egg weight, per cent shell, shell surface density, plasma, adrenal and hepatic ascorbic acid and renal L-gulonolactone oxidase activity were measured. 3. The strains differed in ascorbic acid synthesis, as measured by L-gulonolactone oxidase activity, and tissue ascorbic acid concentration. 4. Comparison of results from birds producing eggs of similar weight but markedly different in shell strength detected neither a shell strength group x strain interaction nor an effect of shell strength group on plasma and hepatic ascorbic acid and activity of L-gulonolactone oxidase. 5. The results did not support the hypothesis that tissue ascorbate and ascorbic acid biosynthesis are reduced in old hens producing weak eggshells.

In two trials, the effects of F-strain Mycoplasma gallisepticum (FMG) on the contents of egg yolks from commercial Single Comb White Leghorn laying hens were investigated over a production cycle. Ten hens were assigned to each of 8 (trial 1) or 16 (trial 2) negative pressure fiberglass biological isolation units. Birds in half of the total units served as sham-inoculated controls, and those in the other half were inoculated with FMG at 12 wk of age. Eggs were collected and yolks were harvested at various times during the prepeak, peak, and postpeak periods of both trials for constituent analysis. Yolk constituents analyzed in these trials included moisture, total lipids, cholesterol, triglycerides, phospholipids, and fatty acids. In both trials, total yolk lipid at 22 wk of age was significantly decreased in birds inoculated with FMG. In trial 1, yolk cholesterol at 28 wk was significantly decreased in FMG-inoculated birds. Yolk linoleic acid in trial 1 and yolk stearic and arachidonic acids in trial 2 were significantly increased in FMG-inoculated birds compared to FMG-free birds. In trial 2, yolk myristic, palmitoleic, and oleic acid percentages were significantly decreased in FMG-inoculated birds compared to FMG-free birds. These data suggest that alterations in egg production in commercial layers in response to an FMG infection at 12 wk of age are associated with changes in yolk composition.

The inconsistent beneficial responses to dietary ascorbic acid (AsA) may be due to dietary factors that alter biosynthesis or tissue turnover of AsA. It has been suggested on the basis of altered tissue AsA that dietary fluoride is a determinant of biosynthesis in chickens. Fluoride may enter the food chain of poultry via industrial contamination, feed ingredients and drinking water. The goal of this study was to ascertain whether dietary fluoride at 300 mg/kg influences l-gulonolactone oxidase (GLO) activity in commercial meat-type chickens. The experimental diet was fed from day-old to 3 weeks and responses measured. Growth and feed conversion were not affected by fluoride in the diet. Dietary fluoride neither inhibited nor enhanced GLO activity nor did it increase or decrease AsA concentration in plasma, liver, kidney, adrenal gland and muscle (pectoralis major). Tissue AsA concentration in ascending order was adrenal > liver > kidney > pectoralis major > plasma. The results are consistent with that reported for the rat and calculations based on the results eliminate fluorine contamination for the inconsistent responses of immature chickens to dietary AsA.

The present study examined the effect of supplemental ascorbic acid (AsA) and ascertained if genotype is a determinant of biosynthesis and the response of strains to dietary AsA. Slow- (Ottawa Meat Control; OMC) and fast-growing (Peterson Enhanced x Hubbard; PEH) chicks were fed 1000 mg/kg AsA from 1 to 10 weeks of age. The activity of l-gulonolactone oxidase (GLO) was used to measure biosynthesis and estimated synthetic capacity (ESC) computed. Body weight was not affected by diets and relative kidney weight decreased with age. In 1 week, dietary AsA increased plasma AsA and inhibited GLO activity with a greater reduction in OMC birds. At 10 weeks, GLO activity was depressed almost uniformly in both strains. Strain by age and diet by age interactions were detected for GLO activity and ESC with significantly greater decline in PEH birds and birds fed supplemental AsA. The results demonstrated that dietary AsA inhibited biosynthesis in meat type chickens and the response at 10 weeks was not influenced by growth rate; and the age dependent decline in biosynthesis was more pronounced in the commercial PEH birds. The result suggests that such strains may be compromised in some situations. Research using multiple dietary levels of AsA, commercial strains, and defined stressors is warranted.

1. The purpose of the study was to determine the stability of dietary ascorbic acid and the reproductive responses of broiler breeder chickens to supplemental 75 mg ascorbic acid/kg diet. 2. Six breeder flocks of 13,000 birds each were studied. Egg production, eggshell porosity, fertility, hatchability and plasma ascorbic acid were measured. 3. Storage of the diets under dry heat resulted in a linear decrease in ascorbic acid content and the rate of decline was 5-fold higher in the supplemented diet. 4. Differences were not detected between treatments in egg production, egg weight, eggshell porosity, fertility, hatchability or plasma ascorbic acid. 5. The results did not provide evidence of a beneficial reproductive response to the inclusion of ascorbic acid in commercial broiler breeder diets.

The objective of this study was to adapt an assay to measure L-gulonolactone oxidase (GLO) activity, the final step in ascorbate synthesis, in chickens and use the procedure to study the effect of gender, age, and food deprivation. To adapt a procedure used for mammalian tissues the kinetic constants were estimated using chicken kidney and assay conditions optimized in terms of storage of tissue and homogeneity of distribution. A series of experiments were conducted using the standardized assay with individual animals as the experimental unit. Gender differences were detected only in mature birds with male chickens having lower GLO activity than females. Time-course changes in GLO activity in immature chicks were best characterized by a segmented response function consisting of a parabola joined to a straight line. The maximum value was estimated to occur at 13 days and from day 16 declined linearly. The functional relationship did not provide evidence of an early lag period or a peak at 4 weeks in immature chickens. Food deprivation in matched groups of birds demonstrated the effect of food on GLO activity in chickens. Food and water deprivation for 12 h and food deprivation for 24 h had no significant effect on GLO activity. Food deprivation for 48 h caused a significant decrease in GLO activity and it was not further depressed by deprivation for 72 h. Initial GLO activity was restored within 24 h of repletion. The results clearly demonstrated that gender, age, and starvation are determinants of ascorbate synthesis in chickens.