Greater Growth Rate Research Articles

Dikaryon development in Flammulina velutipes

In Flammulina velutipes the origin and development of the dikaryon (as indicated by the formation of clamp connexions) has been studied in colonies derived either from a multi-basidiospore inoculum or from a paired inoculum of two compatible monokaryons. Occasional clamped hyphae arose, but not until 3–4 d after inoculation, and no further hyphae of this kind were initiated once the growing fringe of the colony had become established. In colonies with diameters of 40–70 mm, both clamped and unclamped leading hyphae were present in the growing fringe. The eventual dominance of the clamped hyphae may be due to their greater growth rate. No anastomoses were seen in the monokaryon. When compatible monokaryons from separate inocula met and clamped hyphae were formed, no development of the clamped condition arose in advance of the growing, clamped hyphae. There was no evidence that extensive nuclear migration plays a part in dikaryotization as it does in Coprinus cinereus and Schizophyllum commune.

Effects of Diffused Aeration and Stocking Density on Growth, Feed Conversion, and Production of Florida Red Tilapia in Cages

AbstractThe effects of four levels of diffused aeration (0, 6, 12, and 24 hours/day) and two stocking densities (400 and 600 fish/m3) on the culture performance of caged Florida red tilapia were evaluated in 1 m3 cages in a 2 ha watershed pond on St. Croix, U.S. Virgin Islands. Fish obtained a nutritionally‐complete (36% protein), floating feed from demand feeders for 143 to 146 days. Diffused aeration had no significant (P > 0.05) effect on fish growth, survival, feed conversion, and production in cages. Combined across all levels of diffused aeration, fish stocked at 400/cage had a greater growth rate (2.21 vs. 1.97 g/day), larger final body weight (370 vs. 335 g), and a lower feed conversion ratio (1.69 vs. 1.80) than fish stocked at 600/cage (P < 0.05). The final biomass of fish stocked at the higher density (181 kg/m3) was greater than at the lower density (140 kg/m3). The enhancement of water exchange rates by diffused aeration did not increase tilapia growth rate or production in cages.

Tall Fescue Endophyte: Effect on Congenital Development and Pup Growth in Mice

This study was designed to assess effects of a diet containing endophyte (Acremonium coenophialum)-infected tall fescue seed on litter growth and development in mice. Twenty pairs of mature CD-1 mice were allocated to dietary treatments containing 50% (wt/wt) rodent chow plus either 50% endophyte-infected tall fescue seed or seed that was not infected. At parturition, six pups of approximately equal BW and sex ratio were selected from each litter and fostered to each of the dams for suckling, resulting in four suckling groups. Pups born to dams fed the infected diet weighed less at birth and experienced developmental delays in BW gain and in eye opening (16.7 vs. 13.7 d) regardless of the foster dam's diet. Pups born of dams fed the diet that was not infected attained the greatest growth rates and weaning weights; those suckling dams fed the diet that was not infected demonstrated the largest gains. Pups born of and suckled by dams fed the infected diet demonstrated greatly reduced growth rates and weaning weights compared with the other groups. Results suggest that the congenital effect on pups born of dams fed an infected diet was significant in lowering the growth rate of the pups during suckling. The dam's ability to provide nourishment to the pups also was lowered when fed this diet. When these two factors were combined, the differences were greater than for either factor separately.

Genetically based differences in susceptibility of white spruce to the spruce bud moth

The susceptibility of white spruce, Piceaglauca (Moench) Voss, leaders to damage by the spruce bud moth, Zeirapheracanadensis Mut. & Free., was assessed for 72 half-sib families at four half-sib family test sites and in one seedling seed orchard in New Brunswick. Trees of intermediate height (1.5–3.75 m) were the most damaged, and damage in one year was positively correlated to damage in the next. During 2 consecutive years, half-sib family explained only 1% of the variation in damage when all four test sites were analysed together. However, half-sib family explained between 2.9 and 7.9% of the variation in damage at individual sites. At the four test sites, mean growth reductions of trees in the two most susceptible families were estimated to be approximately 30% higher than those of trees in the two least susceptible families. When all 72 families were ranked with respect to height, trees in the most susceptible and least susceptible families were ranked very poorly and highly, respectively. This suggested that trees in more susceptible families were smaller because of damage by the spruce bud moth. However, this pattern was observed at all sites, including one where bud moth damage was negligible. Thus even in the absence of damage by the spruce bud moth, trees in these least susceptible families had a greater growth rate, in terms of height, than trees in the most susceptible families. This indicates that selection for plant traits reducing susceptibility to bud moth may be compatible with breeding programs attempting to improve height growth. Implications of these results for tree improvement programs are discussed.

Synergism of testosterone propionate with growth hormone in promoting growth of hypophysectomized rats: effect of sexual differentiation

The effect of testosterone propionate (TP), alone and in combination with porcine GH, on the growth of hypophysectomized rats was investigated. An initial study determined doses of TP and GH which would result in a synergistic response. Hypophysectomized male rats, approximately 40 days of age, received GH at doses of 5, 25 and 62.5 micrograms/day administered in two injections/day at 08.00 and 16.00 h. At all doses of GH, administration of TP at 100 micrograms/day significantly enhanced the GH-stimulated rate of growth. This growth enhancement by TP was greatest in combination with GH at 25 micrograms/day. In a subsequent study, growth responses to 25 micrograms GH/day and 100 micrograms TP/day were examined in animals with differing degrees of sexual differentiation. Sex groups were: intact males, males castrated at 11 days of age and females administered 100 micrograms TP at 3 days of age (masculinized rats), and males castrated at 2 days of age and normal females (non-masculinized rats). In all sex groups, growth of hypophysectomized rats was stimulated by GH. Genetic sex and masculinization did not influence the response to GH. Masculinized hypophysectomized rats exhibited significantly greater rates of growth and final live, empty body, liver and kidney weights than non-masculinized hypophysectomized rats. All sex groups other than normal females responded synergistically to the combination treatment of GH plus TP. Rats that experienced neonatal exposure to testosterone became programmed to respond to testosterone and demonstrated greater rates of growth and body and organ weights when administered the combination of GH plus TP. These data indicate that TP synergizes with GH to promote growth of hypophysectomized rats appropriately programmed to respond.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Extended Daylength on Autumn Growth Dynamics of Juvenile Atlantic Salmon, Salmo salar

The growth and growth dynamics of juvenile Atlantic salmon (Salmo salar) exposed from mid-August to mid-December to either a normal light:dark cycle (LDN) or a constant 16-h light:8-h dark (LD 16:8) photoperiod were compared. Exposure to the LD 16:8 resulted in 38.1% of the fish entering the upper modal group (UMG) of the length–frequency distribution, while only 15.4% entered the UMG under LDN. The length at which fish entered the UMG (critical fork length) did not differ between photoperiods. Fish in the small (5.8–6.7 cm) and middle (6.8–7.7 cm) size-ranges under LD 16:8 had greater growth rates than fish in the same size-ranges under LDN. Fish in the large (8.3–9.2 cm) size-range showed no significant variation in growth rates between photoperiods. At the end of the experiment, mean thyroxine (T4) levels were significantly (P < 0.05) lower in fish from the LD 16:8 photoperiod (1.69 ng/mL) in comparison with LDN fish (3.96 ng/mL). Triiodothyronine (T3) levels and the T3/T4 ratio were elevated under LD 16:8.

Triple-deck flow over unsteady surface disturbances: The three-dimensional development of Tollmien-Schlichting waves

Both the incompressible and supersonic external flows past a small unsteady three-dimensional wall distortion (situated on an otherwise flat plate) are considered, the description of the flow being based on triple-deck theory. Firstly a linearised study is made (which is directly akin to a linearised stability analysis). In the incompressible case the (Tollmien-Schlichting) modes with largest growth rate correspond to planar (2-D) modes, whilst in the case of supersonic flows, for which it is well known that 2-D triple-deck theory predicts only stable Tollmien-Schlichting waves, it is found that unstable Tollmien-Schlichting modes are possible, with the greatest growth rate corresponding to one of the oblique waves. Secondly an initial value approach is implemented, the lower deck equations being solved by a Fourier transform approach in both the streamwise and crossflow directions (together with a Crank-Nicolson scheme in the timewise direction). The computations (i) confirm the formation of Tollmien-Schlichting waves and (ii) suggest that non-linearity causes a breakdown, with the solution at a point becoming singular at some finite time; compared to analogous 2-D calculations, these 3-D calculations seem to breakdown at an earlier time. We speculate as to the consequences of this phenomenon.

Contribution of lipoprotein lipase activity to the differential growth of three adipose tissue depots in young broiler chickens

Abstract 1. The growth of three distinct adipose tissue depots around the abdomen, neck and thigh was measured in a commercial strain of broiler, and related to the changes in activity of lipoprotein lipase within each depot. 2. At 10 d of age there was no significant difference between the weights of the depots. Thereafter the abdominal fat pad exhibited a much greater rate of growth than the other two depots so that by 55 d of age the abdominal fat pad was 4 times the size of the leg depot and 3.4 times the size of the neck depot. 3. Changes in total lipoprotein lipase activity for all three depots showed a similar pattern to the changes in their weight. 4. When [14C]‐VLDL was injected intravenously into birds at 15 and 57 d of age the percentage taken up into the abdominal fat pad was greater than that into the other two depots at both ages. At 57 d of age the abdominal fat pad had a 2.3‐fold greater uptake than at 15 d whereas the other two depots showed no significant differences at the two ages. 5. ...

Anabolic implant and frame size effects on growth regulation, nutrient repartitioning and energetic efficiency of feedlot steers.

Rates of growth and partitioning of nutrients among tissues were measured in large (Simmental x [Hereford x Brahman]; n = 34) and very large (Chianina x Angus and Maine Anjou x Angus; n = 37) steers implanted with different anabolic growth regulators. All cattle were fed individually a whole shelled corn (13% crude protein) diet. Implant strategies were: none (n = 13), Ralgro 36 mg (n = 15), Ralgro 72 mg (n = 14), Synovex-S (n = 15) and Ralgro 36-Synovex-S (n = 14) administered at d 0 and 90. Empty body composition of all cattle was measured initially and at 90 d by D2O dilution procedures and at slaughter (average, 182 +/- 4.1 d) by carcass specific gravity. Empty body weight for large and very large cattle averaged 274 and 324 kg (P less than .05) initially and 497 and 603 kg (P less than .05) at slaughter. Empty body protein differed (P less than .05) for large and very large steers and averaged 51 and 61, 67 and 79, and 87 and 103 kg initially, at midpoint and at slaughter, respectively. Percentage empty body fat was lower for very large steers (13.5 vs 15.6%) initially (P less than .05) but was similar for very large and large steers at the midpoint (18.7 vs 18.1%) and at slaughter (23.2 vs 21.9%). Daily rates of empty body gain (DEBG) were greater (P less than .05) for very large vs large steers for both growing and finishing periods and averaged 1.53 vs 1.26 kg/d overall. Daily rates of protein gain (DPG) were similar for very large and large steers for the growing phase (204 vs 202 g/d) but greater (P less than .05) in very large steers for the finishing phase and overall (253 vs 204, and 229 vs 202 g/d). All implant strategies, except R36, increased DEBG and DPG and tended to decrease the percentage of fat in daily gain. In both large and very large cattle, implant growth regulators increased growth rate and partitioned nutrient use away from fat toward protein accretion, with the magnitude of partitioning toward protein increasing with greater rates of growth. These data indicate that anabolic growth regulators are viable strategies to enhance lean beef production in steers, regardless of animal size.

Variation in growth rate within and among full-sib families of Douglas-fir (Pseudotsuga menziesii)

Variation in growth rate in the four uppermost lateral branches of seedlings of Pseudotsuga menziesii (Mirb.) Franco was greatest among individuals within full-sib families. These results are consistent with those from other studies on conifers indicating there is much more within- than among-intraspecific group variation. Since these seedlings were grown in a common garden, it is assumed that the among-individual variation has a genetic basis. The greatest growth rate was in seedlings produced by crossing trees that had the highest average increments of growth; the lowest growth rate was in seedlings produced by crossing trees that had the lowest average increments of growth. However, the seedlings with the lowest growth rate were similar to those produced by crosses between trees with high average increments of growth. This implies that phenotypically superior trees, as assessed in a natural situation, do not necessarily produce superior offspring in their second year of growth. The high within-family variation coupled with the ontogenetic events associated with growth rate implies a complex multigenic control of growth rate. The genetic complexity of an apparently simple developmental event such as growth in length implies that evolutionary or developmental models based on a small portion of the genome may be inadequate.

Age and growth ofAstyanax eigenmanniorum(Cope) (Pisces, Characiformes) from San Roque Lake, Argentina

The age and growth of Astyanax eigenmanniorum from San Roque Lake (Province of Cordoba, Argentina) were studied. During two years, 3,086 specimens were analysed; these were collected monthly by means of a dragging net. Lepidologic studies were made to determine age and growth. Applying the traditional von Bertalanffy's model and Allen's method to length data, growth curves were drawn showing differences in both sexes; females having greater growth rate and asymtotic length than males. The relative condition factor and cephalic index show that during winter life conditions grow worse.

The seasonal pattern of growth of the sea trout ( Salmo trutta L.) from the Vardnes river in northern Norway

The growth pattern of sea trout in the sea was studied by measurement of 2787 tagged individuals before and after their stay in the sea while corresponding measurements of 2180 individual fish ascertained the growth pattern in fresh water. In the sea, there was a period of particularly rapid growth just before the beginning of July. The greatest rate of growth in fresh water was recorded for those sea trout that ascended the river relatively early on, or left the river late the following year. This result may explain the relatively simultaneous timing in northern areas of the migration to the sea of several species of salmonids in spring, and also the high degree of variation seen in the timing of the return migration to fresh water.

Variation in nitrogen response among spring rape ( Brassica napus) cultivars and its relationship to nitrogen uptake and utilization

Growth, development and yield of 40 diverse spring rape ( Brassica napus) cultivars were measured at three different levels of applied nitrogen in the field. There were significant cultivar differences in yield under a limiting N supply and in yield response to higher N application rates. Cultivars with the lowest yields at the lowest N level generally responded more markedly to increase in N application rates than cultivars with higher yields in this treatment. A greater yield response was associated with relatively greater rates of growth and development at higher N levels. Measurements of dry weights and N contents of above-ground plant parts over a period between 42 and 66 days after sowing of the field experiment were used to calculate N-uptake rates and N-utilization (change in dry weight/unit change in N content) indices. Significant cultivar differences were observed only at the lowest N level for N-utilization index and only at the intermediate level for N-uptake rate. If cultivars were grouped on the basis of their geographic origin—Japanese, Canadian, European—those of Japanese origin generally had the highest uptake rates and utilization indices in the respective treatments in which significant differences were detected. Two solution-culture experiments were also conducted in a daylight phytotron at 20/15°C with the same cultivars. Significant cultivar differences in N-uptake rate and N-utilization index were detected with an initial concentration of 1m M N, but not with an initial concentration of 8 m M N. Cultivar differences in root growth and N uptake per unit root dry weight were significant at both concentrations. Again, most of the cultivars with the highest uptake rates or utilization indices were of Japanese origin. Uptake rate was correlated with uptake rate per unit dry weight, but not with initial root dry weight or increase in root weight over the course of the experiment. The significance of geographic variation in N-uptake rate in both field and controlled experiments is discussed with particular reference to the use of this character as a selection criterion in breeding programs utilizing recently developed another culture techniques.

Numerical study of the spectrum of broadband electrostatic noise in the magnetotail

A numerical study is made of the spectrum of broadband electrostatic noise (BEN) generated by ion beams in the plasma sheet boundary layer (PSBL), as introduced by Grabbe and Eastman (1984). Two cases are analyzed. The first case has a single hot electrons species present. In that case, two modes are unstable. One is a beam‐acoustic mode, which drives instabilities over a broad frequency and angular range. This is a negative energy resistive medium instability in which inverse Landau damping causes growth and which occurs in a broad‐angle cone centered about the magnetic field. Another is an ion‐ion two‐stream instability which has a much narrower frequency and angle range and considerably greater growth rates. The angle of maximum growth of this instability is typically around 75° (as in the work by Grabbe (1985a, b)) and is found to vary from the high 60s to the low 80s. It is only unstable in the low‐frequency part of the BEN spectrum. The polarization, as measured in the lower part of the spectrum, is predicted to occur at an angle near 75° with respect to the magnetic field, in very good agreement with previous polarization measurements. The high‐frequency part of the spectrum is predicted to be more closely field aligned. A second case analyzed is that in which a second population of cold electrons (arising from diffusion from the lobe into the plasma sheet boundary layer) is present. This cold electron population significantly increases the upper frequency range of the unstable spectrum, and the associated growth rates are enhanced. Its primary influence is found to be on the field‐aligned component at small angles, but if the concentration of cold electrons is sufficiently large, it decreases the growth rates of the oblique ion‐ion instability, thus stabilizing the larger angles. The field‐aligned spectrum undergoes a transition from a negative energy to a positive energy two‐stream instability. This second electron population generates the very high frequency part of the observed BEN spectrum that is just below the plasma frequency and creates wave amplitudes that are as large as the one produced by the large‐angle instability. These results explain the gradual rise in the upper frequency range of BEN as the spacecraft approaches the plasma sheet from the lobe, and the sudden jump in that frequency up to near the plasma frequency upon crossing the PSBL. Also, it is predicted that the frequencies of field‐aligned waves close to the plasma frequency are produced in a region where the cold electrons diffuse in from the lobe, and the large angles of growth are produced outside this region in the PSBL.

Six-year field performance of container-grown and bare-root black oak seedlings inoculated with Pisolithustinctorius and outplanted on two Ozark clear-cuts

The effects of container culture and infection with Pisolithustinctorius (Pers.) Coker and Couch on growth and survival of black oak (Quercusvelutina Lam.) seedlings outplanted on two Missouri Ozark clear-cuts were examined over 6 years. Container-grown 1-0 seedlings exhibited height and diameter growth superior to bare-root stock, and mycorrhizal plants were taller than nonmycorrhizal plants during the first two to three field seasons. Thereafter, container-grown and bare-root, and mycorrhizal and nonmycorrhizal seedlings grew at comparable rates such that treatment differences in height and diameter had been greatly reduced 6 years after outplanting. Seedling growth and survival differed between sites, a response resulting from differential soil moisture availability and the nature of competing vegetation of the two planting sites. Shading by more abundant herbaceous and low woody vegetation on a comparatively mesic site likely resulted in greater mortality and less stem growth than on a xeric site during years 1 to 3. However, seedlings that grew to heights sufficient to overtop neighboring vegetation on the mesic site exhibited comparatively greater growth rates in years 4 to 6. As a result, after 6 years, the xeric site was occupied by a relatively large number of small seedlings, while the mesic site was characterized by fewer but larger seedlings.

Viscous Nongeostrophic Baroclinic Instability

Calculations have been performed of the (linear) stability of a baroclinic flow to three-dimensional perturbations. Both the simple Eady basic state and the rotating Hadley cell of Antar and Fowlis are considered. The independent influences of the Richardson (Ri), thermal Rossby (baroclinicity), Ekman, and Prandtl numbers are examined, as well as the influences of the angle of orientation of the horizontal wave vector and the wavelength. It is shown that if the wavelength is allowed to vary freely, disturbances of the Eady type are preferred (i.e., have greatest growth rate) unless Ri and Ekman numbers are small enough and the thermal Rossby number is large enough. In the latter case, disturbances whose angles of orientation are almost symmetric and whose wavelengths are mesoscale are preferred. If, on the other hand, the wavelength is fixed at a mesoscale size, only the symmetric and almost symmetric modes have growth. By allowing the wave vector orientation to deviate from purely symmetric, it is noted that the region of instability (i.e., critical Ri) is increased, the extent of which is greater for longer wavelength. For Prandtl number = 1, permitting the angle to be nonsymmetric demonstrates the existence of two maxima in growth rate at opposite angles of orientation and with very different energetics. For Prandtl number far enough from one and for large enough dissipation, only one of these two modes has positive growth rates. Growing oscillatory modes were found for some cases.

Oviposition preferences in relation to larval growth rates and survival in the pine beauty moth, Panolis flammea

Abstract. 1. Adult female pine beauty moths, Panolis flammea (D & S), when given a choice of whole plants or needle pairs of four provenances of Lodgepole pine, Pinus contorta (Douglas), laid most eggs on that provenance on which the larvae attained their greatest growth rates.2. When presented with a greater number of Lodgepole pine provenances and Pinus sylvestris L, P.flammea oviposition preferences reflected the trade‐off between growth rate and survival.3. There is some evidence to suggest that the moths are responding to the monoterpene composition of the plants.4. Adult moths showed no preference for Lodgepole pine needles of a range of ages (1–4 years), ovipositing uniformly on all age classes.

Dormancy and Growth of American Ginseng as Influenced by Temperature

Abstract American ginseng (Panax quinquefolium L.) roots have a dormancy period which can be satisfied by exposure to low temperatures of 0° to 10°C for about 100 days. Three-year-old roots of ginseng were weighed, given variable periods (≥ 50 days) of low temperature (5°C), planted in vermiculite in pots, and grown in light or dark at 5°, 10°, 15°, or 20°. After 50 to 100 days of storage at 5°, stem growth occurred at all temperatures except 20°. At this temperature, a minimum of 75 days at 5° was required to satisfy dormancy. Stem growth rate was relatively constant at 5° and 10° but increased with storage time when grown at 15° or 20°; leaf growth rate was affected similarly, except that no leaf growth occurred at 5°. If optimum cold storage and growth requirements were not met, the plants appeared abnormal and had reduced root dry weights. After 100 days of storage, the greatest growth rate was observed at 15° and 10°. Plant growth rate was the least at 5° and 20°.

Effect of housing systems on the energy balance of laying hens.

In each of 2 experiments 192 medium large laying hens (Warren WSL), of 19 to 27 and 29 to 42 weeks old, respectively, were put in 2 respiration chambers in cages and on wire floor in the same environmental conditions. Production performance and utilization of energy were estimated. Feed conversion (feed intake in kg/eggs produced in kg) was slightly lower in the cage system as a result of a greater egg weight. Hens in cages had a greater growth rate. With about the same energy intake in experiment 1 and a lower in experiment 2 the better performance in cages can only be explained by a possibly slightly better utilization of the energy and in particular by a lower requirement of maintenance energy in cages. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Characterization of post-weaning traits of Simmental and Hereford bulls and heifers

ABSTRACTPost-weaning growth, dry-matter intake, carcass characteristics, chemical composition of the 9th to 11th rib section and food conversion efficiency were evaluated for Simmental bulls (15) and heifers (18) and Hereford bulls (17) and heifers (14) from approx. 240 days of age to 470 days of age. Within each breed × sex sub-class, animals were assigned to one of three energy intake levels: (1) ad libitum, (2) 795 kJ metabolizable energy (ME) per kg0·75 per day and (3) 544 kj ME per kg0·75 per day.Simmentals tended to exhibit higher post-weaning growth rate and consumed more dry matter than Herefords. At ad libitum intakes, efficiency estimates (gain/food) were greater initially but decreased more rapidly for Herefords than for Simmentals. No differences were observed in efficiency estimates between Herefords and Simmentals fed at 795 kJ ME per kg0·75 per day and both breeds fed at this level improved in efficiency as time on test increased.Bulls tended to have greater growth rate, and consume more dry matter than heifers. At ad libitum food intake, bulls were more efficient than heifers and the decrease in efficiency of the two sexes was parallel. Heifers fed at 795 kJ ME per kg0·75 per day had a constant efficiency throughout the test while bulls improved in efficiency.