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Biomedical subjects

G A Benson

Publications and source records attributed to G A Benson.

10 recordsLinked to original sources
PubMed2002

Milk production and economic measures in confinement or pasture systems using seasonally calved Holstein and Jersey cows.

This 4-yr study examined total lactation performance of dairy cows in two feeding systems: pasture-based and confinement. Spring and fall calving herds were used and each seasonal herd had 36 cows on pasture and 36 cows in confinement with 282 Holstein and 222 Jersey cows included over seven seasonal replicates. Pasture-fed cows received variable amounts of grain and baled haylage depending upon pasture availability. Confinement cows received a total mixed ration with corn silage as the primary forage. Data were collected on milk production, feed costs, and other costs. Pasture-fed cows produced 11.1% less milk than confinement cows. Across treatments, Jerseys produced 23.3% less milk than Holsteins, but calving season and various interactions were not significant. Feed costs averaged $0.95/cow per day lower for pastured cows than confinement cows. Feed costs were lower for Jerseys than Holsteins and for cows calving in spring. Income over feed costs averaged $7.05 +/- 0.34 for confinement Holsteins, $6.89 +/- 0.34 for pastured Holsteins, $5.68 +/- 0.34 for confinement Jerseys, and $5.36 +/- 0.34 for pastured Jerseys; effects of breed were significant but treatment, season, and interactions were not. Economic factors such as labor for animal care, manure handling, forage management, and cow culling rates favored pastured cows. Higher fertility and lower mastitis among Jerseys partially offsets lower income over feed cost compared with Holsteins. Milk production was lower in this study for pasture-based systems but lower feed costs, lower culling costs, and other economic factors indicate that pasture-based systems can be competitive with confinement systems.

Animal Feed↗
PubMed2002

Reproduction, mastitis, and body condition of seasonally calved Holstein and Jersey cows in confinement or pasture systems.

Dairy cows in confinement and pasture-based feeding systems were compared across four spring-calving and three fall-calving replicates for differences in reproduction, mastitis, body weights, and body condition scores. Feeding systems and replicates included both Jersey and Holstein cows. Cows in confinement were fed a total mixed ration, and cows on pasture were supplemented with concentrates and provided baled hay or haylage when pasture supply was limiting. Breeding periods were for 75 d in spring or fall. Reproductive performance did not differ significantly due to feeding system or season. Jerseys had higher conception rates (59.6 vs. 49.5 +/- 3.3%) and higher percentages of cows pregnant in 75 d (78.1 vs. 57.9 +/- 3.9%) than Holsteins. Cows in confinement had 1.8 times more clinical mastitis and eight times the rate of culling for mastitis than did cows on pasture. Jerseys had half as many clinical cases of mastitis per cow as Holsteins. Only 41 +/- 5% of confinement Holsteins remained for a subsequent lactation, starting within the defined calving season compared with 51 +/- 5% of pastured Holsteins and 71 and 72 +/- 5% of Jerseys, respectively. Body weights and condition scores were generally higher for confinement cows than pastured cows, and Jerseys had higher condition scores and lower body weights than Holsteins. In summary, pastured cows had fewer clinical cases of mastitis, lower body condition scores, and lower body weights than confinement cows. Holsteins were less likely to rebreed, had more mastitis, higher culling rates, and lower body condition scores than Jerseys.

Animal Feed↗
PubMed1983

Structure-activity studies on sulfamate sweetners III: structure-taste relationships for heterosulfamates.

Eleven heterosulfamates have been synthesized, characterized, and evaluated for sweetness. Measurements of the molecular dimensions (x, y, z, and V) of these sulfamates and 22 others that had been reported previously and evaluated for sweetness have been made using Corey-Pauling-Koltun space-filling models. The first-order molecular connectivities (1Xv) of all the heterosulfamates have been calculated. The statistical technique of linear discriminant analysis was applied to the complete set of 33 compounds and to a reduced set of 27 compounds. The analysis was performed using the above five variables (x, y, z, V, and 1Xv) and various subsets thereof. For the complete set of compounds, seven variable subsets were identified which yielded correct classifications of 27 and 28 compounds. A similar analysis of the reduced set did not improve the misclassification rate.

Chemical Phenomena↗
PubMed1979

Metabolic studies with nonnutritive sweeteners cyclooctylsulfamate and 4-methylcyclohexylsulfamate.

The nonnutritive sweeteners cyclooctylsulfamate and 4-methylcyclohexylsulfamate were fed separately to female Wistar albino rats, and the urine was examined for the possible metabolites cyclooctylamine, cyclooctanone, cyclooctanol, 4-methylcyclohexylamine, 4-methylcyclohexanone, and cis- and trans-4-methylcyclohexanols. The average percent conversions to cyclooctylamine, cyclooctanone, and cyclooctanol were 0.127, 0.08, and 0.092, respectively. The average percent conversions to 4-methylcyclohexylamine and 4-methylcyclohexanone were 0.007 and 0.0013, respectively. No cis- or trans-4-methylcyclohexanol metabolites were found. With cyclooctylsulfamate, 42% was recovered unchanged from the urine. Cyclooctyl- and cycloheptylsulfamates were metabolized to a greater extent than cyclopentylsulfamate, which, in turn, was metabolized to a greater extent than cyclohexylsulfamate (cyclamate) and 4-methylcyclohexylsulfamate.

Animals↗
PubMed1978

Metabolic studies of the nonnutritive sweeteners cyclopentylmethylsulfamate and cyclopentylsulfamate: determination of metabolites in rat urine.

The nonnutritive sweetener sodium cyclopentylmethyl-sulfamate was fed to Wistar albino rats. The urine was collected for 3 days, combined, and examined (GLC) for the metabolites cyclopentyl-methylamine and cyclopentylmethanol. The percent conversion to these metabolites was 0.077 and 0.0102, respectively. The percent conversion to these to cyclopentylmethylamine was the lowest conversion to amine observed when compared to the metabolism of three other sweet sulfamates, cyclopentylsulfamate, cycloheptylsulfamate, and cyclooctylsulfamate, previously administered to rats. The average excretion of unmetabolized sulfamate was 15.4%. Sodium cyclopentylsulfamate was fed to rats over 9 days, and an analysis was carried out for the metabolites cyclopentylamine, cyclopentanone, and cyclopentanol. A decrease in the level of metabolites occurred after the first 3 days.

Animals↗
PubMed1977

Metabolic studies with the nonnutritive sweetener cycloheptylsulfamate.

The nonnutritive sweetener cycloheptylsulfamate was administered orally to rabbits and rats. The urine of each species was separately collected for 3 days and examined for the metabolites cycloheptylamine, cycloheptanone, and cycloheptanol and for cycloheptylsulfamate. A previously tested GLC method was adapted for the determination of the metabolites. Cycloheptylsulfamate was assayed by hydrolysis and subsequent measurement of the absorbance of the product formed (lambdamax=489 nm) by the liberated amine with p-benzoquinone. The conversions to the metabolites were 0.276, 0.390, and 0.170%, respectively, in rabbits and 0.064, 0.022, and 0.017%, respectively, in rats.

Animals↗
PubMed1976

Determination of the nonnutritive sweetener sodium cyclopentylsulfamate and three of its metabolites, cyclopentylamine, cyclopentanone, and cyclopentanol, in urine of rats and rabbits.

The nonnutritive sweetener sodium cyclopentylsulfamate was fed to Wistar albino rats and New Zealand White rabbits. Urine was collected for 3 days after feeding, combined, and examined for the metabolites cyclopentylamine, cyclopentanone, and cyclopentanol and for sodium cyclopentylsulfamate was assayed by hydrolysis in acidified dioxane-water and subsequent measurement of the absorbance of the product formed (lambdamax = 490 nm) by the liberated amine with p-benzoquinone. The average conversion to cyclopentylamine, cyclopentanone, and cyclopentanol was 0.103, 0.171, and 0.054% in the rabbit and 0.057, 0.016, and 0.008% in the rat, respectively.

Amines↗
PubMed1976

Structure-activity studies on sulfamate sweeteners.

The structure-activity relationships governing sulfamate sweeteners are reviewed under the headings: size of the reduced ring, changes in the sulfamate function, substitution of hydrogen in the ring, and substitution of carbon in the ring and open-chain compounds. Fifteen compounds have been synthesized with a view to testing the limitations on structural changes which may be made within these categories without loss of sweetness. The presence of the grouping greater than CHN(R)SO3- is suggested as a necessary but not a sufficient condition for a compound to be sweet-tasting. Thus, the B center of the Shallenberger A-H,B theory of sweetness is best regarded as being -SO3- rather than -SO2- for sulfamates. Threshold levels and relative sweetness have been determined for seven sulfamates.

Amines↗