Subsequent Growth Period Research Articles

Compensatory responses of swine following protein insufficiency in grower diets.

Four trials involving 426 crossbred pigs were conducted to determine the effect of protein restriction during early growth on subsequent performance and carcass characteristics at 100 kg. The experimental animals averaged 25 to 27 kg initial weight in trials 1, 2 and 3, and 18.2, 22.7 and 27.3 kg in three weight groups in trial 4. Pigs were fed corn-soybean meal supplemented diets of 12, 14 or 16% protein. Protein restriction (12 or 14% protein diets), to 52 kg in trial 1 and during the initial 4-wk period in trials 2, 3 and 4, reduced rate and efficiency of growth; performance was reduced more on 12% protein diets. In the subsequent growth period, early protein restriction improved gain and feed to gain ratio. Performance for the total period was similar for pigs fed a 14% protein diet continuously to that of pigs fed a 16 to 14% protein sequence when pigs had an initial weight of 25 kg or more. However, lighter weight pigs did not completely compensate for decreased performance during the early 4-wk period. Carcass characteristics were similar for all protein sequences.

Dietary nitrogen concentration in growing cattle: the effect on growth rate, feed utilization and body composition

ABSTRACTThirty-six British Friesian castrated male cattle (steers) were included in an experiment to measure the response in live-weight gain and body composition to feeding barley-based diets containing increasing levels of formaldehyde-treated soya bean meal. The response was measured between 100 kg and 350 kg or 450 kg live weight. The basal diet of pelleted whole barley and 10% ground oat straw contained 16·6g to 38·5 g nitrogen per kg dry matter. There were no overall differences in live-weight gain or in feed intake. Between 100 kg and 250 kg live weight, live-weight gain increased significantly from 1 08 to 1·24 kg/day when the lowest and highest nitrogen diets respectively were fed (P<0·05). Animals given the highest nitrogen diets also consumed significantly more feed (P<0·05). Conversely, in the subsequent growth period between 250kg and 350kg live weight, live-weight gain decreased from 109 to 0·89 kg/day when the highest nitrogen diet was fed. There were no significant differences in feed intake.Groups of four animals per treatment were slaughtered at 365 kg and 465 kg fasted live weight. When animals were fed 23·7 g nitrogen per kg dry matter and slaughtered at 365 kg fasted live weight there was significantly more omental fat (P<0·05) and the fat depth at the 12th rib was greater than in animals fed the higher levels of nitrogen. The differences in omental fat weight between the 23·7 g nitrogen and 16·6g nitrogen per kg dry matter diets were not significant. The proportion of crude protein (nitrogen × 6·25) in the boneless 9-10-1 lth rib of animals fed 23·7 g nitrogen per kg dry matter was the lowest of all diets and significantly less than the two highest nitrogen diets (P<0·05). When similar animals were slaughtered at 465kg there was a non-significant trend for omental fat weight and fat depth at the 12th rib to decrease as the nitrogen content of the diet increased.

Effects of water stress onLupinus albus

Abstract Plants of Lupinus albus were grown in controlled-environment rooms at 18°c day and 13°c night temperatures. During one of 3 growth stages between main stem floral initiation and the end of first order lateral flowering, plants were moved to another room at 28°c day and 20° c night temperatures. At each growth stage some plants were given adequate water while others were restricted. At the end of each treatment, plants were returned to the low temperature and received adequate watering. High temperatures depressed the weight of vegetative parts when applied before flowering but had no significant effect during subsequent growth periods, although growth and development rates were increased. Weight of vegetative parts was depressed by water stress but, except for the preflowering treatments, reproductive growth rate was increased by stress during the growing period. Final seed yield, however, was depressed by water stress and by high temperatures during the preflowering and main stem flowering periods even in well watered plants.

Unscheduled DNA synthesis after partial UV irradiation of the cell nucleus: Distribution in interphase and metaphase

Cells of an euploid strain of the Chinese hamster synchronized in the G1 phase were microirradiated in the nucleus with a laser UV microbeam (λ = 257 nm) and pulse-labelled with [ 3H]thymidine. In autoradiographs of cells fixed immediately after the pulse unscheduled DNA synthesis (UDS) was found restricted to the microirradiated part of the nucleus. The rate of UDS varied with the UV energy applied and the post-irradiation incubation time. In other experiments chromosome preparations were established after an additional chase and a subsequent growth period. In 28 mitotic cells autoradiographic label was found concentrated on a few chromosomes which lay adjacent to each other in one part of the metaphase plate. The distribution of label on the chromosomes could clearly be distinguished from patterns which originate from semi-conservative DNA synthesis within S phase. The label on chromosomes of microirradiated cells thus represents UDS. Our findings support the following ideas on the arrangement of interphase chromosomes: (1) Decondensed interphase chromosomes may occupy rather compact territories. (2) Chromosomes do not necessarily exhibit a close and permanent association with their respective homologues.

The role of an epithelial occlusion zone in the termination of vitellogenesis in Hyalophora cecropia ovarian follicles

At the end of vitellogenesis, the follicular epithelium of Hyalophora cecropia follicles forms an occlusion zone that can halt the access of horseradish peroxidase to the oocyte surface in living follicles, and of lanthanum nitrate in fixed preparations. It is proposed that this barrier is responsible for terminating the uptake of blood proteins by the oocyte. Although three types of interfollicle cell junctions were observed, only tight junctions appeared to be responsible for the observed impermeability. Sodium dodecyl sulfate-acrylamide gel electrophoresis of [ 3H]leucinelabeled proteins revealed no change in the protein synthetic pattern during the transformation of follicles from vitellogenesis to the subsequent terminal growth period; in addition, pinocytotic figures continued to be formed in the postvitellogenic oocyte. These findings suggest that the epithelial secretion which the oocyte is known to deposit in yolk during vitellogenesis continues to be sequestered in the absence of blood proteins after occlusion zone formation. The proposal explains the origin of a layer of membrane-limited bodies which occupy the cortex of the oocyte in mature silkworm eggs, and which differ markedly in appearance from the protein yolk spheres assembled earlier.

Cytogenetics of somatic cell hybrids

Karyotypes of hybrid cells were studied in continuous uncloned cultures by Q- and C-bandings. Cultures were initiated by virus-mediated or spontaneous cell fusions from normal human diploid fibroblasts and mouse heteroploid RAG cells. Heterokaryons containing complete genomes of both parental cells randomly lost chromosomes from both species. The majority of cells in early growth stages, however, still possessed a nearly complete human genome. The rate of human chromosome loss in subsequent growth periods was not uniform, being gradual in some and rapid in others. The initially predominant 2n human-1s mouse (1h:1m) type was soon replaced by a less frequent 2n human-2s mouse (1h:2m) type. Over an increased period of time in mass culture, the number of stemlines decreased. One stemline, often a (1h:2m) type with a greatly reduced human complement, outgrew the others and occupied the entire culture. Therefore, the usual process of clonal isolation may confer a negative selection bias against cell hybrids retaining a large number of human chromosomes. Hybrid stemlines with stable karyotypes were established in the present HAT-agar selection system before 36 days after fusion had elapsed.

Effect of density on growth and survival of rainbow trout

Groups of rainbow trout ( Salmo gairdneri) were kept at five different densities during an initial feeding period of 42 days and a subsequent growth period of 180 days. They were then kept at the same density for 55 days. Differences between groups in mean weights and mortality were found as early as the end of the initial feeding period. At the end of the 180-days growth period the differences in mean weight between density groups were large. Differences in condition ( K) factor were also found at the end of this period. Groups at high densities had the lowest growth rate and K factor. When groups were kept at the same density, those originally at high densities showed the highest relative growth. It is concluded that high densities depressed the growth rate, and that compensatory growth occurred when the densities were standardized. It is important to take density into account when ranking families or progeny groups for growth performance.

Effect of density on growth and survival of artificially reared Atlantic salmon

Groups of salmon ( Salmo salar) from two localities were kept at five different densities during the initial feeding period of 42 days and a subsequent growth period of 205 days. They were then kept at the same density for 95 days. Differences in mean weight between fish from different localities were found as early as the end of the initial feeding period. No marked differences were found between mean weights of fish held at different densities during the initial feeding period, while the mortality rate of fry decreased with higher densities for both strains. At the end of the 205-day growth period the differences in mean weight between strains and between density groups within a strain were large. Significant interaction between locality and density was also found. Part of this interaction is due to scale effects. When groups were kept at the same density, those originally at high densities showed the highest relative growth, and also had the highest K-factor at the end of this period. It is concluded that high densities depressed the growth rate, and that compensatory growth occurred when the densities were standardized. It is important to take density into account when ranking families or progeny groups for growth performance in selective breeding trials.

Carbon-13 nuclear-magnetic-resonance spectroscopy of whole cells and of cytochrome C from Neurospora crass grown with (S-Me-13C)methionine

Neurospora crassa cytochrome C biosynthetically labelled with [S-Me-13C]methionine was prepared and analysed by 13C nuclear-magnetic-resonance spectroscopy. The methyl group of methionine is extensively incorporated into an N-trimethyl-lysine-72 residue arise from S-adenosylmethionine transmethylation, and that the methyl carbons of methionine residues are sufficiently close to the haem centre to experience chemical shifts from the ring currents of the tetrapyrrole pi electrons and broadening due to binding of methionine-80 with the haem, as well as interaction of the S-E113C]methyl groups with the paramagnetic iron centre. Although whole cells of the labelled Neurospora produced a 13C resonance at the expected position for the methionyl methyl group most of the methyl label was diverted into N-tetra-alkyl ammonium compounds. After an active state of growth these labelled N-methyl compounds appear, in the main, to be low-molecular-weight derivatives of choline which, if associated with membrane, are in a sufficiently fluid environment to have short rotational correlation times. During a subsequent dormant growth period these compounds become associated to some extent with relatively more immobile phases as a result of membrane binding or an increase in membrane rigidity.

Labile and nonlabile energy in blue grama (Bouteloua gracilis) as influenced by temperature, water stress, and fertilizer treatments

Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] plants from a native shortgrass prairie were subjected to four treatments at three different temperatures in a growth chamber experiment to evaluate the dynamics of labile and nonlabile energy components in different plant organs. At high temperature regimes (24°/13° and 29.5°/18 °C day–night) blue grama plants accumulated comparatively greater amounts of labile and nonlabile energy in the three organs, viz., shoots, crowns, and roots, than at low temperature regime (13°/7 °C). The labile energy in shoots at the three temperature regimes continued to increase up to a peak value recorded at 90 days and then declined during the subsequent 30-day growth period. On the other hand, the accumulation of labile energy in roots and crowns continued till final harvest. Irrigated plus N-fertilized plants accumulated more labile and nonlabile energy in their shoots than did the irrigated plants, and the latter accumulated more than the fertilized and the control plants. The labile and nonlabile energy components in fertilized plants were at lower levels than the control plants during the 120-day growing period, resulting in net negative energy balance as compared with control plants. Higher temperature, irrigation, and irrigation plus nitrogen application decreased the nonlabile:labile ratios in the plants.

Calcium in Relation to Respiratory Activity of Peanut and Linseed Plants

The present study deals with the changes in respiratory activity of peanut ( Arachis hypogaea var. Big Japan) and linseed ( Linum usitatissimum var. NP [RR] 5) plants as influenced by different levels of calcium employing sand culture technique. It has been shown that low levels of calcium cause stimulation of leaf respiration. Under complete deficiency of calcium, however, while high respiration rate is observed in linseed leaves; in case of peanut plants the respiration rate is almost similar to that of control at most harvests. Furthermore, it has been observed that magnitude of increase in respiration varies with the age of the plant. In peanut plants, high levels of calcium though initially results in promotion of respiration but at later stages of growth it shows inhibitory effects. In case of linseed plants, initially there is an inhibition which seems to recover at subsequent growth periods.

Comparison of S1 and Open‐Pollination Progenies of Astragalus cicer L. for Certain Agronomic Characters1

Self‐ (S1) and open‐pollination (O.P.) progenies of 24 self‐compatible S0 plants of cicer milkvetch (Astragalus cicer L.) were evaluated in the field for forage yield, height, spread, vigor score, and date of flowering. One generation of inbreeding had such a deleterious effect on plant vigor that paired S1 and O.P. progenies could be differentiated visually. Forage yields of the S1 progenies were approximately 50% of the forage yields of O.P. progenies. Considerable variation occurred among S0 plants for inbreeding depression. Inbreeding delayed flowering approximately 10 days in the seedling year, but there was little difference between the S1 and O.P. progenies for mean date of flowering in subsequent growth periods. There was no relationship between the self‐compatibility of the S0 parents and forage yields of their S1 and O.P. progenies.There were significant differences among S0 parents for general combining ability. Open‐pollination progenies of several S0 plants with average vigor performed better than similar progenies of S0 plants with excellent vigor.Simple correlation coefficients between forage yield, height, spread, vigor score, and date of flowering were highly significant. The associations between vigor score and forage yield were the highest with coefficients of —0.93, —0.91, and —0.92 for the one harvest in 1970 and the first and second harvests in 1971, respectively.

Growth of excised tomato roots in glucose; an effect on ageing

IAA, 1-NAA, 2,4-D, kinetin, and benzyl adenine were inhibitory to the growth of excised tomato roots in glucose medium. GA3, myo-inositol, and two antiauxins, 2-NAA and NMSP, were stimulatory but growth did not approach that in sucrose medium. Glucose was not inhibitory in the presence of optimal sucrose, and was stimulatory in the presence of suboptimal sucrose. Glucose pretreatment markedly enhanced the ageing of roots in a subsequent growth period in sucrose, and the significance of this is discussed in relation to the growth stimulation caused by the antiauxins.

Genesis of mitochondria in neurospora crassa.

Observations with the light and electron microscopes have suggested three possible mechanisms for the formation of new mitochondria:' 2 (1) growth and subdivision of existing mitochondria, (2) denovo synthesis, and (3) derivation from other nonmitochondrial membranous structures. In an attempt to distinguish between these basic possibilities, we have carried out the following experiment: Cells fully labeled with a radioactive constituent of mitochondria were transferred to nonradioactive medium. During the subsequent logarithmic growth period purified mitochondrial fractions were isolated, and the distribution of label among their individual mitochondria was determined using a quantitative radioautographic technique.3, 4a In this type of experiment, the distribution of autographic grains among mitochondria could be expected to fit one of three patterns: (1) A dispersive pattern in which label would be distributed among all mitochondria, the average grain count per mitochondrion decreasing as a function of cell growth. This pattern is consistent with mitochondrial multiplication by division. (2) A conservative distribution in which the proportion of labeled mitochondria would decrease during growth in unlabeled medium as a logarithmic function of time, the average grain count per mitochondrion in the labeled population remaining the same. Such a pattern is consistent with de-novo synthesis. (3) An intermediate pattern, in which the label would not be randomly distributed, and the proportion of labeled individuals would decrease less rapidly than in the truly conservative case, the total grain count of the labeled population decreasing, remaining the same, or increasing slightly. This would be consistent with formation of mitochondria from labeled (possibly structural) precursors. In these studies radioactive choline was used as a label, because lecithin into which it is incorporated is a major constituent of mitochondrial phospholipids.5 6 Efficient and chemically specific labeling was obtained by working with a cholinerequiring strain of Neurospora crassa (chol-1, #34486).7 This cholineless strain appears to be blocked at the earliest step in the synthesis of choline from ethanolamine; it can make neither mononor dimethyl-ethanolamine, though it can use these compounds for the synthesis of choline.8 The experiment which has been outlined can yield the information needed, provided several prerequisites are fulfiled: (a) The cells under study must constitute a homogeneous population with a reproducible and prolonged logarithmic growth phase. (b) The mitochondrial fractions used for analysis must be free of contamination by other cellular structures. (c) The radioactive choline. which is incorporated must behave as a stable mitochondrial label. Much of the experimental evidence is directed toward demonstrating that these prerequisities are satisfied. Materials and Methods.-Materiais: Cytochrome c, Type III (horse heart) was purchased from Sigma Chemical Company; C14and H3-methyl-labeled choline chloride were purchased

Protein Requirements of Suckling Age Pigs1

Thirty-nine pigs weaned at 3-weeks of age were used to obtain further information on the protein requirement for growth of pigs during the period of 3- to 8-weeks of age. No significant difference resulted in rate of gain of the pigs due to the use of rations containing approximately 16, 20, 24 and 28% of protein. There was a definite trend toward more efficient utilization of feed for gain as the level of dietary protein increased. Nitrogen balance studies were conducted to determine the influence of level of dietary protein upon nitrogen retention by pigs fed 16, 20, 24 and 28% protein diets during the period from 3- to 8-weeks of age. A highly significant difference (P<0.01) resulted in the percentage of absorbed nitrogen retained due to protein level. Likewise, there was also a highly significant difference in amount of nitrogen retained per unit of metabolic size (k0.75) due to protein level with significantly less nitrogen being retained by the pigs fed the 16% protein diet than by the pigs fed diets containing any of the other levels of protein. It appears that the percentage of dietary protein required to promote acceptable gains in 3- to 8-week old pigs is somewhat less than that required to promote satisfactory nitrogen retention. It is suggested that pigs weaned at 3 weeks of age require at least 20% oi dietary protein of high quality to promote maximum nitrogen retention, during the early stages of the subsequent growth period.

Cyclic variations in the peptidase and catheptic activities of yeast cultures synchronized with respect to cell multiplication

The total “over-all” dipeptidase and proteinase A activities of normal and X-irradiated cultures of Saccharomyces cerevisiae were assayed during various physiological states. Yeast cultures first starved for some hours in succinate buffer were then made to undergo two or three somewhat synchronous cell divisions in a yeast extract growth medium. The cytological characteristics were followed as well as the content of UV-absorbing cytoplasmic materials. The enzymic activities were expressed on a per-cell basis and also per protein content. During the starvation phase the protein content per cell remained high but a marked decrease of dipeptidase activity per cell was noted, while the proteinase A activity showed a minor decrease. During the subsequent growth and cell division period marked cyclic variations occurred in the enzyme activities, more marked for the peptidase and less for the proteinase. The highest enzymic activities always coincide with stages preparatory to cell division, and the lowest levels were reached during each subsequent budding period. After 15,000 r of X-irradiation the first division occurred normally in timing as in protein and enzyme content. The second division was delayed and many of the cells inhibited from budding. After this division the nitrogen content per cell increased to about 150 per cent of the normal, and the enzyme content remained high. The cells were left in a state preparatory to cell division. No appreciable enzyme activity was detected in the culture medium during the various phases of normal yeast cell growth or in the post-irradiation period. The results indicate that cycles of increased proteolysis form essential steps during certain stages of cell growth preparatory to cell division. The idea is advanced that the proteinases and peptidases may be operative in the intracellular reactions aiming at the replenishment of the metabolic amino acid pool necessary for protein synthesis.