scholarly journals An examination of the effect of autumn closing date on over-winter herbage production and spring yield

2021 ◽  
Author(s):  
C. Looney ◽  
D. Hennessy ◽  
A. Wingler ◽  
A. Claffey ◽  
M. Egan
Keyword(s):  
Growth Rates ◽  
Lower Growth ◽  
Closing Date ◽  
Herbage Quality ◽  
High Feed ◽  
Lower Growth Rate ◽  
Dead Material ◽  
Grass Growth ◽  
Tiller Density ◽  
Spring Yield

Altering autumn management affects the herbage mass available in spring. An experiment was established to determine the effect of five autumn closing dates (CDs) on herbage production, herbage quality, leaf, stem and dead proportions and tiller density over winter. In the study 50% of the herbage available in spring was accounted for by autumn CD. Each 1 d extra a sward was closed from 25 September to 9 December increased herbage mass by 16 kg DM/ha in spring. Swards closed earlier (25 September–26 October) had consistently higher herbage masses in spring (1,301 kg DM/ha) compared to swards closed later (11 November–9 December; 703 kg DM/ha). Later closed swards had greater herbage quality compared to earlier closed swards (organic matter digestibility = 852 and 825 g/kg DM, respectively) due to increased stem and dead material in the grazing horizon of earlier closed swards. There was no effect of autumn CD on sward quality in the subsequent defoliation in spring. However, following the initial spring grazing there was an effect of autumn CD on subsequent grass growth rates; swards closed in October had a lower growth rate (33 kg DM/ha per day) compared to swards closed in November and early December (49 kg DM/ha per day). Results indicate that earlier autumn closing is beneficial to meet high-feed demand in spring but can affect sward quality and growth rates in spring.

scholarly journals Revisiting Connell: competition but not as we know it

2017 ◽  
Vol 98 (6) ◽  
pp. 1253-1261 ◽  
Author(s):  
Jenna M. Gordon ◽  
Antony M. Knights
Keyword(s):  
Growth Rates ◽  
Natural Populations ◽  
Small Scale ◽  
Nearest Neighbour ◽  
Negative Effects ◽  
Lower Growth ◽  
Neighbour Distance ◽  
Lower Growth Rate ◽  
Pair Competition ◽  
Reduced Density

Space is one of the primary limiting resources for organisms on the intertidal rocky shore. This paper examined the effect of reduced density on key traits (mortality and growth) on the intertidal barnacles, Chthamalus montagui and Semibalanus balanoides, on the mid-shore in Plymouth, UK. Intra- and interspecific treatments comprising of C. montagui and S. balanoides were manipulated to reduce densities at two similar sites. Changes in mortality and operculum growth were assessed over an 8-week period using digital photography. Covariates of growth included nearest neighbour distance, competition between closest pairs and initial size. Conflicting patterns were observed when comparing growth rates between treatments and sites. At Site 1, interspecific treatments had a lower growth rate than intraspecific treatments, whereas at Site 2, interspecific growth rates were higher. ANCOVA showed that nearest neighbour distance had no significant effect on growth, but when comparing differences in growth of closest neighbouring pairs, C. montagui treatment showed evidence of competition whereas S. balanoides did not. ANCOVA analysis indicated no difference in growth between each outcome of pair competition, suggesting winners are initially bigger than losers. Comparisons of mortality between treatments indicated mortality over time with no significant differences observed between treatments, but response surface methodology (RSM) revealed no effects of competition on mortality of S. balanoides, but negative effects of both intra- and interspecific competition on C. montagui survivorship. Examination of natural populations of barnacles in the mid-shore indicated there was strong spatial variation in growth rates, perhaps driven by small-scale differences within sites.

scholarly journals Production of Maize Silage is Possible in Integrated Systems with Arboreal Component

2019 ◽  
pp. 1-9
Author(s):  
Roberta Aparecida Carnevalli ◽  
Emanuelle Beatriz Cruz e Santos ◽  
Joadil Gonçalves De Abreu ◽  
Larissa Fernanda Garcia ◽  
Admar Junior Coletti ◽  
...  
Keyword(s):  
Integrated Systems ◽  
Maize Silage ◽  
Lower Growth ◽  
Lower Growth Rate ◽  
Silage Quality ◽  
Silage Production ◽  
Viable Seeds ◽  
High Level ◽  
Grass Growth ◽  
Plot Design

Distribution of the intercropped plants determines the production but it is highly dependent on the machinery of the property. Producers, who harvest silage row by row, depend on plantings with greater spacing. This study was aimed to evaluate the maize intercropped for cultivated silage in 0.90 m between rows, with grass under the shade and full sunlight conditions. Maize with brachiaria grass was tested in four sowing densities (0, 2, 4 and 6 kg of pure and viable seeds per hectare). The factorial treatments (2x2x4) were distributed in a split-plot design with four repetitions. The maize agronomic characteristics and the silage quality were evaluated. There was a high level of competition when associated with maize, piatã and eucalyptus. Aggressive piatã grass growth, with light restriction by trees, have affected strongly the maize forage mass-produced, and consequently, reduced silage production. Regarding grain yield, the intercrop with ruziziensis grass was superior (210%) to the intercrop with piatã grass. It was mainly influenced by the low yield in the piatã grass intercropped under shade conditions. This pattern was different for ruziziensis because it was a less aggressive grass in terms of growth. For plantations with 0.90 m of spacing, there was a light restriction. The maize intercropped under the shade of trees must be done with lower growth rate grass to reduce competition and maintain the yield.

scholarly journals Differences on allocation of available resources, in growth, reproduction, and survival, in an exotic gastropod of Physidae compared to an endemic one

2010 ◽  
Vol 100 (3) ◽  
pp. 275-279 ◽  
Author(s):  
Verónica Núñez
Keyword(s):  
Growth Rates ◽  
Native Species ◽  
Energy Allocation ◽  
Reproductive Period ◽  
Functional Requirements ◽  
Lower Growth ◽  
Physa Acuta ◽  
Local Species ◽  
Lower Growth Rate ◽  
Maximum Shell Length

Physa acuta Draparnaud, 1805 is an invasive gastropod that can affect local species. In Argentina, it is widespread and abundant, even in environments inhabited by the native species Stenophysa marmorata Guilding, 1828. Its predominance raises the question whether this could be explained by a more successful energy allocation in functional requirements (growth, reproduction and survival) compared to S. marmorata. This study was aimed at comparing growth rates, as well as survival and fecundity, between both species under laboratory conditions. Individuals born on the same day were grouped in four per aquaria and kept under controlled conditions of food, light, and temperature. Snails were weekly measured (maximum shell length), and growth rates were calculated using the Von Bertalanffy's equation. The number of eggs and survivors were grouped by week. Stenophysa marmorata was larger at birth than Physa acuta and invested more energy in growth, delaying sexual maturity. This resulted in a disadvantage in fecundity and survival compared to P. acuta, which had a lower growth rate but matured earlier and survived longer. Furthermore, the growth of P. acuta was not affected by reproduction, its reproductive period was longer, consequently with more eggs laid than S. marmorata.

scholarly journals Effects of Modification of Light Parameters on the Production of Cryptophycin, Cyanotoxin with Potent Anticancer Activity, in Nostoc sp.

Toxins ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 809
Author(s):  
Alexandros Polyzois ◽  
Diana Kirilovsky ◽  
Thi-hanh Dufat ◽  
Sylvie Michel
Keyword(s):  
Light Stress ◽  
Red Light ◽  
Major Effect ◽  
High Light Intensity ◽  
Efficient Production ◽  
Lower Growth ◽  
Noticeable Increase ◽  
Lower Growth Rate ◽  
Industrial Use ◽  
Effect Of Light

Cryptophycin-1 is a cyanotoxin produced by filamentous cyanobacteria. It has been evaluated as an anticancer agent with great potential. However, its synthesis provides insufficient yield for industrial use. An alternative solution for metabolite efficient production is to stress cyanobacteria by modifying the environmental conditions of the culture (Nostoc sp. ATCC 53789). Here, we examined the effects of light photoperiod, wavelength, and intensity. In light photoperiod, photoperiods 24:0 and 16:8 (light:dark) were tested while in wavelength, orange-red light was compared with blue. Medium, high, and very high light intensity experiments were performed to test the effect of light stress. For a 10-day period, growth was measured, metabolite concentration was calculated through HPLC, and the related curves were drawn. The differentiation of light wavelength had a major effect on the culture, as orange-red filter contributed to noticeable increase in both growth and doubled the cyanotoxin concentration in comparison to blue light. Remarkably, constant light provides higher cryptophycin yield, but slightly lower growth rate. Lastly, the microorganism prefers medium light intensities for both growth and metabolite expression. The combination of these optimal conditions would contribute to the further exploitation of cryptophycin.

Effects of lice infestation on the growth of beef heifers in Victoria

1984 ◽  
Vol 24 (125) ◽  
pp. 140 ◽  
Author(s):  
PJ Bailey ◽  
WAD Carroll ◽  
B Knee
Keyword(s):  
Growth Rates ◽  
Beef Heifers ◽  
Lower Growth ◽  
High Rainfall ◽  
Main Species ◽  
Western Victoria ◽  
Linognathus Vituli

Ten experiments were carried out to examine some of the effects of lice infestation on heifers grazing on six commercial properties in the high rainfall areas of Victoria. In all experiments, famphur, a pour-on lousicide, effectively controlled lice populations (main species Linognathus vituli). Lice infestation was associated with lower growth rates in only two experiments. Significant correlations between lice infestation and liveweight gain of untreated heifers were found in three of ten experiments, but infestation accounted for only 23-30% of the variation in liveweight gain. The results support other studies conducted in Western Victoria, and the need for routine whole herd treatment against lice is questioned.

scholarly journals Widespread variation in heat tolerance and symbiont load are associated with growth tradeoffs in the coral Acropora hyacinthus in Palau

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Brendan Cornwell ◽  
Katrina Armstrong ◽  
Nia S Walker ◽  
Marilla Lippert ◽  
Victor Nestor ◽  
...  
Keyword(s):  
Climate Change ◽  
Large Scale ◽  
Habitat Restoration ◽  
Natural Resistance ◽  
Lower Growth ◽  
Coral Reef Resilience ◽  
The Face ◽  
Lower Growth Rate ◽  
Acropora Hyacinthus ◽  
The Cost

Climate change is dramatically changing ecosystem composition and productivity, leading scientists to consider the best approaches to map natural resistance and foster ecosystem resilience in the face of these changes. Here we present results from a large-scale experimental assessment of coral bleaching resistance, a critical trait for coral population persistence as oceans warm, in 221 colonies of the coral Acropora hyacinthus across 37 reefs in Palau. We find that bleaching resistant individuals inhabit most reefs but are found more often in warmer microhabitats. Our survey also found wide variation in symbiont concentration among colonies, and that colonies with lower symbiont load tended to be more bleaching resistant. By contrast, our data show that low symbiont load comes at the cost of lower growth rate, a tradeoff that may operate widely among corals across environments. Corals with high bleaching resistance have been suggested as a source for habitat restoration or selective breeding in order to increase coral reef resilience to climate change. Our maps show where these resilience corals can be found, but the existence of tradeoffs with heat resistance may suggest caution in unilateral use of this one trait in restoration.

Do abiotic mechanisms determine interannual variability in length-at-age of juvenile Arcto-Norwegian cod?

2002 ◽  
Vol 59 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Geir Ottersen ◽  
Kristin Helle ◽  
Bjarte Bogstad
Keyword(s):  
Growth Rates ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Water Masses ◽  
Inverse Relation ◽  
Lower Growth ◽  
Density Dependent ◽  
The Barents Sea ◽  
The Mean ◽  
Dependent Growth

For the large Arcto-Norwegian stock of cod (Gadus morhua L.) in the Barents Sea, year-to-year variability in growth is well documented. Here three hypotheses for the observed inverse relation between abundance and the mean length-at-age of juveniles (ages 1–4) are suggested and evaluated. Based on comprehensive data, we conclude that year-to-year differences in length-at-age are mainly determined by density-independent mechanisms during the pelagic first half year of the fishes' life. Enhanced inflow from the southwest leads to an abundant cohort at the 0-group stage being distributed farther east into colder water masses, causing lower postsettlement growth rates. We can not reject density-dependent growth effects related to variability in food rations, but our data do not suggest this to be the main mechanism. Another hypothesis suggests that lower growth rates during periods of high abundance are a result of density-dependent mechanisms causing the geographic range of juveniles to extend eastwards into colder water masses. This is rejected mainly because year-to-year differences in mean length are established by age 2, which is too early for movements over large distances.

The impact of endophyte on the health and productivity of sheep grazing ryegrass-based pastures

1999 ◽  
Vol 7 ◽  
pp. 11-17
Author(s):  
L.R. Fletcher ◽  
B.L. Sutherland ◽  
C.G. Fletcher
Keyword(s):  
Perennial Ryegrass ◽  
Growth Rates ◽  
Plasma Prolactin ◽  
Sheep Grazing ◽  
Wild Type ◽  
Lower Plasma ◽  
Lower Growth ◽  
Respiration Rates ◽  
Neotyphodium Lolii ◽  
The Impact

The health and production of sheep grazing perennial ryegrass with and without wild-type endophyte (Neotyphodium lolii) has been studied in several trials over a number of years. Lambs/ hoggets grazing predominantly perennial ryegrass swards with endophyte developed moderate to severe ryegrass staggers in summer and autumn, while those grazing endophyte-free ryegrass did not. Lambs/hoggets grazing ryegrass with endophyte also had more dags, lower growth rates, lower plasma prolactin levels, higher body temperatures and respiration rates under warm humid conditions. Most of these adverse responses were more severe in summer and autumn when endophyte toxin concentrations were highest. Many of these symptoms are similar to those described for the "autumn ill thrift" syndrome in New Zealand. Keywords: dags, endophyte, flystrike, growth rates, hyperthermia, Neotyphodium, perennial ryegrass, prolactin, ryegrass staggers, sheep

Settlement and Metamorphosis in Barnacles and Decapods

2020 ◽  
pp. 223-254
Author(s):  
Paulina Gebauer ◽  
Luis Giménez ◽  
Iván Hinojosa ◽  
Kurt Paschke
Keyword(s):  
Adult Population ◽  
Subsequent Development ◽  
Suitable Habitat ◽  
Pelagic Larva ◽  
Lower Growth ◽  
Settlement Behavior ◽  
Biphasic Life Cycle ◽  
Settlement And Metamorphosis ◽  
Lower Growth Rate ◽  
Adult Habitat

Settlement and metamorphosis are two crucial processes in organisms with a biphasic life cycle, forming the link between the pelagic larva and benthic juvenile-adult. In general, these processes occur during the final larval stage. Among crustaceans, settlement behavior and the cues that trigger settlement and metamorphosis have been studied in greater depth in barnacles than in decapods, likely a result of the former losing the ability to move after they join the benthic juvenile-adult population, undergoing metamorphosis. Both barnacles and decapods respond to different environmental cues associated with the adult habitat, such as substratum, biofilm, and the presence of conspecifics. In the absence of cues, larvae can delay their metamorphosis for a period of time. This ability to prolong the development can be advantageous because it increases the probability of settling in a suitable habitat. However, delayed metamorphosis has also associated costs (e.g., smaller size, lower growth rate, and higher mortality), which may be carried over to subsequent development stages, with consequences for recruitment.

Dietary effect on bovine milk fat conjugated linoleic acid content

2000 ◽  
Vol 25 ◽  
pp. 283-293
Author(s):  
F. Lawless ◽  
J.J. Murphy ◽  
S. Fitzgerald ◽  
B. O’Brien ◽  
R. Devery ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Linoleic Acid ◽  
Conjugated Linoleic Acid ◽  
Growth Rates ◽  
Milk Fat ◽  
Methyl Esters ◽  
Bovine Milk ◽  
Fold Increase ◽  
Linoleic Acid Content ◽  
Grass Growth

AbstractConjugated linoleic acid (cis-9, trans-11-C18:2; CLA) in milk arises as a result of microbial biohydrogenation of dietary linoleic and linolenic acids in the rumen (Kepler and Tove, 1967). Milk fat CLA concentrations were significantly (P<0.05) higher when cows were fed silage supplemented with pulp’n brew (a mixture of brewers grains, a by-product of the brewing industry, and sugar beet pulp in dry matter proportions of 0.65:0.35), compared with silage alone (Trial 1). Intake of spring grass resulted in a 2.1–fold increase in milk fat CLA concentrations over cows receiving autumn grass. Throughout lactation in Trial 2, spring calving cows produced higher milk fat CLA concentrations (from 0.5-2.7 g/100 g fatty acid methyl esters (FAME)) than autumn calving cows (0.3-1.7 g/100 g FAME); the former having spent 80% and the latter 50% of lactation on pasture. The CLA content was higher in late lactation milk compared with early lactation milk in both herds. There were no significant differences in milk yields or milk constituent yields between the herds. Manufacturing milk obtained between March and September was analyzed for milk fatty acid composition and the data correlated with grass growth throughout the season. Significant positive correlations were obtained between grass growth rates and concentrations of CLA and linolenic acid in milk fat. The data indicate that seasonal variation in milk fat CLA concentrations may be attributed to variation in pasture growth rates.

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