Browsing Elmer E. Rasmuson and BioSciences Libraries by Subject "Growth"
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Effects of milk intake, growth and suckling efficiency on suckling behavior of muskox (Ovibos moschatus) calvesGeneral theory on parental provisioning predicts that mammalian offspring receiving more milk should show longer suckling bouts, greater total suckling time, longer intervals between bouts, and greater suckling success. For muskoxen I found that suckling bout duration and suckling success were positively correlated with milk intake during some but not all stages of lactation. Neither interval between suckling bouts, nor total suckling time, was correlated with milk intake. Growth of calves was positively related to milk intake, and among calves of the same age suckling efficiency (intake/min suckling) was highly related to body weight. Therefore, milk intake affects growth rate, which in turn affects suckling efficiency. The overriding influence of calf body size and suckling efficiency limits interpretation of differences in suckling behavior that can be attributed to milk intake by muskox calves and therefore to the provisioning strategy of the cow.
Environmental regulation of growth in black brantBody size is an important determinant of life history traits such as survival and fecundity. There is a positive correlation between growth during the first summer and final body size in goose populations. I examined how environmental factors influence growth in Black Brant (Branta bernicla; hereafter brant) goslings. Growth declined seasonally and varied among brood-rearing areas. However, the pattern was not consistent among years. Models containing only environment and maternal effects explained 75% of variation in gosling mass, indicating that little of the observed variation in size is directly of genetic origin. Heritability did not differ from zero for both mother-daughter and father-daughter regressions. I also conducted an experiment to study the effect of gosling density on food abundance, feeding behavior, and development of brant goslings, in two habitat types important to brant: (1) Carex subspathacea grazing lawns and (2) slough levees which contain Triglochin palustris. Variation in grazing pressure was experimentally manipulated. Biomass and offtake of C. subspathacea was higher in lightly grazed plots than in heavily grazed plots even though goslings within heavily grazed plots spent more time feeding. Within slough levee habitat there were no differences between heavily and lightly grazed plots in either biomass or offtake of T. palustris. Peck rates were lower in slough levee habitat than in grazing lawns. Change in mass over an eight hour trial was positively correlated with the amount of forage biomass in the plot at the start of the trial. I found no variation in internal morphometrics or body composition among goslings. I also examined the relationship between forage available within a brood-rearing area, the number of birds using the area, and gosling growth. Annual variation in use of brood-rearing areas was correlated with forage availability. Gosling mass was negatively correlated with brood numbers when examined across all areas, however, within each brood-rearing area, the relationship between mass and numbers of birds was positive. I did not see a relationship between estimates of food availability (per m²) and brood numbers. Spatial variation in growth among habitats may result from habitats varying in quality and quantity of forage.
Feeding and growth of seasonal cohorts of larval walleye pollock (Theragra chalcogramma) in Auke Bay, AlaskaLarval walleye pollock, Theragra chalcogramma (Pallas), typically occur in the water column in synchrony with peak densities of prey. A primary objective of this investigation was to examine and compare growth rates of larval pollock. The growth rate of a synchronous cohort (hatched 10-14 May, 1986) was found to be significantly higher (P<0.05) than that of an earlier cohort (hatched 15-19 April, 1986) . Synchronous cohorts are larvae that occur simultaneously with the maximum densities of herbivorous copepods. Growth rates were determined by otolith analysis. Prey densities and water temperature were implicated as causes of the observed differences in growth. Prey densities were approximately 3 times higher for the synchronous cohort than the early cohort. Additionally, the early cohort experienced water temperatures 2-3°C colder than the synchronous cohort. Results suggest that synchronous larval walleye pollock have higher growth rates and may have higher survival rates.
The kinetics of glucose limited growth by a marine yeastThe kinetics of glucose limited growth by a marine yeast, shown to be a Rhodotorula species, have been studied in a continuous culture apparatus. The saturation constant, in synthetic media, has been calculated to be 0.25 mg/l, on the assumption that saturation kinetics are followed, The maximum growth rate was determined in both synthetic media, and artificial sea water. On the basis of inhibition kinetics, the kinetic behavior of this yeast in the marine environment has been predicted. The effect of temperature on the maximum growth rate has been determined and, on the assumption of a similar effect on the saturation constant, the saturation constant has been postulated to be in agreement with similar values determined for other microorganisms.