Showing papers on "Compensatory growth (organism) published in 1997"

Catch-up growth

Abstract: I. Introduction II. Catch-up Growth: Theoretical Considerations A. Definition B. Catch-up growth vs. compensatory growth C. Canalization D. Catch-up growth vs. resumption of a normal height velocity E. Types of catch-up growth F. Assessment of duration and success of catch-up growth III. Secondary Growth Disorders and Subsequent Catch-up Growth A. The early studies B. Malnutrition C. Celiac disease D. GH deficiency E. Hypothyroidism F. Corticosteroid excess G. Intrauterine growth retardation (IUGR) IV. Mechanisms Regulating Catch-up Growth A. The neuroendocrine hypothesis B. The growth plate hypothesis V. Determinants of Normal Growth and Their Changes During Catch-up Growth A. Introduction B. The somatotrophic axis C. The epiphyseal growth plate VI. Concluding Remarks

Growth compensation in juvenile atlantic salmon: responses to depressed temperature and food availability

Abstract: This study examines behavioral and physiological responses of juvenile At- lantic salmon (Salmo salar) adopting alternative life history patterns following a period of reduced growth. We manipulated the growth rates of premigratory and nonmigratory salmon by either reducing food availability or maintaining water at low temperature (4-60C). A third group of fish was kept at ambient temperatures (12-14'C) and fed ad libitum to provide a control. Fish in both experimental groups exhibited compensatory growth after the manipulation period, even though the manipulations had slowed growth rather than caused mass loss. The timing and duration of compensatory growth were affected by the nature of the constraint and the developmental pathway adopted. Compensatory responses were more persistent and stronger among premigratory fish than among nonmigratory. Fish kept at low temperature did not accelerate growth immediately after transfer to ambient temperatures, but they subsequently grew faster than controls for up to 215 d after the end of the manipulation period. This mitigated the effects of the period of low temperatures, although by the end of the experiment they were still smaller than the controls. Fish on reduced rations showed no such time lag, and they grew significantly faster than controls immediately upon regaining access to full rations. These fish attained the same body size as controls by the end of the experiment (day 215). The manipulations caused fish to reduce their growth in mass more than their rate of skeletal growth, but all fish achieved "normal" mass for their length (as compared to controls) within a week of transfer to full feeding or ambient temperature. The main mechanism underlying compensatory growth rates was apparently the increase of intake rates, although this was insufficient to explain the strong compensation shown by temperature-manipulated fish in the presence of larger (and thus competitively superior) individuals. Instead these fish enhanced their growth rate by ap- parently increasing the duration of the daily feeding period, and avoiding aggressive in- teractions. We interpret the observed compensation for periods of slowed growth as indi- cating that growth rate is normally submaximal and can be increased if the animal has fallen below its expected trajectory; thus premigratory fish may have shown a greater compensation because survival rates during migration are strongly size-dependent.

Effects of compensatory growth on population processes : A simulation study

Abstract: The spatial extent of the canopy or root system of a plant is often used as an index of its potential to acquire resources, such as water and nutrients. This has given rise to the area of influence (AOl) and neighborhood concepts for quantifying competitive interactions between neighboring plants. Both are based on a circle of fixed radius centered on a plant, which presupposes that two plants in close proximity are always strong com- petitors. There is evidence that this is not always the case. In this paper, we present a simple model of plant population dynamics that extends the concept of AO by considering "com- pensatory" growth of root systems. The ability of a plant to grow roots into soil zones free of neighbors in response to competitive pressures is expressed by the value of a single parameter, X. Effects on population attributes resulting from competition in plants with compensatory growth are compared with populations with noncompensatory growth. Simulations show that compensatory plants are better able to utilize available space, have greater biomass, and outcompete noncompensatory plants. The change from a clumped to a regular distribution of individuals due to density-dependent mortality is delayed in noncompensatory plants. These theoretical results suggest that growth plasticity and the resulting asymmetry in space acquisition may play an important role in plant population dynamics.

Effects of compensatory growth on populationprocesses: a simulation study

Abstract: The spatial extent of the canopy or root system of a plant is often used as an index of its potential to acquire resources, such as water and nutrients. This has given rise to the area of influence (AOI) and neighborhood concepts for quantifying competitive interactions between neighboring plants. Both are based on a circle of fixed radius centered on a plant, which presupposes that two plants in close proximity are always strong competitors. There is evidence that this is not always the case. In this paper, we present a simple model of plant population dynamics that extends the concept of AOI by considering “compensatory” growth of root systems. The ability of a plant to grow roots into soil zones free of neighbors in response to competitive pressures is expressed by the value of a single parameter, λ. Effects on population attributes resulting from competition in plants with compensatory growth are compared with populations with noncompensatory growth. Simulations show that compensatory plants are better able to utilize available space, have greater biomass, and outcompete noncompensatory plants. The change from a clumped to a regular distribution of individuals due to density-dependent mortality is delayed in noncompensatory plants. These theoretical results suggest that growth plasticity and the resulting asymmetry in space acquisition may play an important role in plant population dynamics.

Is Weight at Birth a Good Predictor of Weight in Winter for Fallow Deer

Abstract: Young fallow deer ( Dama dama ) held in captivity were weighed at birth and at the onset of winter to test if weight at birth predicted body weight in winter. A positive relationship was obtained between these two measurements. In previous studies, existence of compensatory growth, which accounts for the absence of relationship between these two measurements, was associated with good conditions encountered by populations. In this population, the absence of resource limitation suggested that level of polygyny might be a better predictor of the absence of compensatory growth during the first summer of life.

Compensatory growth of broiler chickens is associated with an enhanced pulsatile growth hormone (GH) secretion: Preferential amplification of GH secretory burst mass

Abstract: 1. The present study was conducted to establish the effect of compensatory growth of broiler chickens on pulsatile growth hormone (GH) secretion. 2. Exposing male broiler chickens to intermittent lighting (IL) at 10 d of age was associated with a transient reduction in body weight gain which was followed by compensatory growth from 4 weeks of age onwards. At 34 d of age, cannulated IL broiler chickens manifesting compensatory growth and control chickens reared under continuous illumination (CL) were serially sampled at 10 min intervals over 5 consecutive hours and plasma GH concentrations measured. The resultant GH time series were analysed by deconvolution analysis. 3. The overall mean GH concentration was higher for IL than for GL broilers. The burst frequency did not differ between lighting treatments, but during each GH surge, IL broilers released a higher GH mass which resulted in higher GH amplitude values. As a consequence, GH production rates of IL broilers during the entire sampling sess...

Análisis de crecimiento de la anchovea hawaiana Encrasicholina purpurea Fowler (Pisces: Engraulidae) en la Bahía de Kaneohe, Oahu, Hawai

Abstract: In this study, growth of Encrasicholina purpurea is analyzed. A general growth curve based upon the Brody-von Bertalanffy equation was determined. The following results were found: L=49.7mm, W=8.4g, k=0.4, t=0.1. Longevity (A 0.95) is close to 7 months, and the natural morrtality rate (M) is 0.4. Males grow faster than females, show a lower A 0.95 and higher M. Individual grow fast during the first development stages, compensatory growth in weight being exhibited from the fifth month of life. Growth rates are consistently higher during spring and summer.

Effect of compensatory growth on production of carcasses to specification.

Abstract: Compensatory growth is utilised in both Australian and New Zealand cattle production systems as an important means of optimising animal growth from a seasonal pattern of pasture availability. (Poppi and McLennan, 1996; Nicol and Kitessa, 1997). However, results from the present experiment, indicate that, during the compensation phase, animals may be less efficient at converting feed to liveweight gain (Muir et al., 1997). It was unclear whether the poor efficiency of feed utilisation was related to deleterious changes in carcass characteristics. The design of the experiment is outlined in Muir et al. (1997). Briefly, 28 Angus and 28 Simrnental steers were purchased as weaners and allocated to two groups containing 14 steers of each breed. Group 1 steers were transferred to a feedlot and adjusted to a concentrate diet of 70% grain and 30% pasture silage, offered ad libitum. Group 1 steers were slaughtered when growth had ceased (80 1 and 948 kg, respectively). Group 2 steers grazed together on pasture until the Angus and Simmental steers had achieved liveweights of 557 and 605 kg, respectively. They were then transferred to the feedlot, adjusted to and given the same ad libitum diet as Group 1. Group 2 steers were slaughtered when they reached the same estimated carcass weight as Group 1 steers. Although there was a clear breed effect, there were no significant differences in carcass weight between ad libitum and compensating steers (Table 1). Steers that had undergone compensatory growth were significantly leaner, as indicated by both subcutaneous fat depth and Japanese marbling scores at the 12th rib (Table 1). Combined weights of commercially important cuts (Topside and Silverside; Butterfield and May, 1966) were significantly heavier (P < 0.00 1) in compensating animals, indicating that growth path can affect the proportion of high value cuts in the carcass. Moreover, the variability associated with carcass weight and individual cut weights tended to be greater in animals that had undergone compensatory growth than in animals fed ad libitum (Table 1). There was also a trend for Simmental steers to be more variable than Angus steers (Table 1). Compensatory growth may result in leaner carcasses which benefits producers under the current grading systems but reduced marbling levels may also impact on future quality grades for Asian markets. Moreover, the present results suggest that compensatory growth may reduce the consistency of carcass quality, reducing returns for producers that supply to contract. Growth path also has significant implications for meat processors and exporters in terms of supply of carcasses and cuts to consumer specification.