scholarly journals Maximising Productivity and Eliminating Campylobacter in Broilers by Manipulating Stocking Density and Population Structure Using ‘Biosecurity Cubes’

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 492
Author(s):  
Genevieve Greene ◽  
Leonard Koolman ◽  
Paul Whyte ◽  
Helen Lynch ◽  
Aidan Coffey ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Growth Rates ◽  
Stocking Density ◽  
Stocking Rate ◽  
Faecal Samples ◽  
Commercial Broiler ◽  
Increase Productivity ◽  
Broiler House

This study investigates the effect of stocking density and population dynamics on broiler growth rates and productivity, while further validating the ability of the biosecurity cubes (BC) to protect birds from Campylobacter. In our methodology, six BC were constructed in a commercial broiler house containing approximately 28,500 birds. During three trials, the BC were stocked at densities of 12, 14, 16, 18, 20 and 22 birds/m2, with the main flock (20 birds/m2) considered the control. Periodically, 10 birds per density were weighed and examined. The Campylobacter status of the birds was monitored via faecal samples using the ISO 10272: 2017. The stocking density for maximum calculated yield was 20 (trials 1 and 2) or 22 birds/m2 (trial 3), followed by 18, 16, 14 and 12. At the stocking rate of 20 birds/m2, the birds in the pen grew faster than those at the same density in the main flock achieving 2 Kg 3–6 days faster. Birds in the BC were observed to be generally healthier, and in some cases, remained Campylobacter negative, even after the main flock was infected. Our results conclude that dividing the flock into sub-flocks of approximately 20 birds/m2 using BC could increase productivity up to 20%, while preventing Campylobacter.

scholarly journals Population dynamics in northwestern China

2021 ◽  
Author(s):  
Xueyan Yang ◽  
Wanxin Li ◽  
Wen Jing ◽  
Chezhuo Gao ◽  
Rui Li ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Population Size ◽  
Ethnic Groups ◽  
Northwestern China ◽  
Average Level ◽  
Han Population ◽  
Sex Structure ◽  
Biological Sex

AbstractThis article analyzes the population dynamics in northwestern China from roughly 2010 to 2020. The area’s dynamics showed a slow, stable increase in population size, a stable increase in the population of non-Han ethnic groups, which increased at a more rapidly than the Han population, and population rejuvenation coupled with a population structure that aged. The biological sex structure fluctuated within a balanced range in northwestern China. Urbanization advanced in northwestern China, throughout this period, but the area’s level of urbanization is still significantly lower than the average level of urbanization nationally.

Population structure, age and growth rates of conifer species and their relation to environmental variables at Malam Jabba, Swat District, Pakistan

2018 ◽  
Vol 31 (2) ◽  
pp. 429-441
Author(s):  
Arsalan ◽  
Muhammad Faheem Siddiqui ◽  
Moinuddin Ahmed ◽  
Syed Shahid Shaukat ◽  
Alamdar Hussain
Keyword(s):  
Population Structure ◽  
Growth Rates ◽  
Environmental Variables ◽  
Age And Growth ◽  
Conifer Species

scholarly journals Optimising grazing for livestock production and environmental benefits in Chinese grasslands

2020 ◽  
Vol 42 (5) ◽  
pp. 347 ◽  
Author(s):  
Warwick B. Badgery ◽  
David Kemp ◽  
Zhang Yingjun ◽  
Wang Zhongwu ◽  
Han Guodong ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Growth Rates ◽  
Alpine Meadow ◽  
Livestock Production ◽  
Desert Steppe ◽  
Stocking Rate ◽  
Typical Steppe ◽  
Artemisia Frigida ◽  
Stocking Rates ◽  
Lamb Growth

Overgrazing has extensively degraded Chinese grasslands. A reduction in stocking rate of 30–50% below the district averages is required to increase the profitability of livestock production and protect vital ecosystem services such as mitigation of greenhouse gases (GHG). Grazing experiments located in the desert steppe, typical steppe and alpine meadow verified the influence of stocking rate and grazing management on livestock production, grassland composition and associated ecosystem services. The desert steppe experiment found lower stocking rates of ~150 SE (where SE is sheep equivalent, which is a 50kg animal) grazing days ha–1 (1 SE ha–1 over 150 days) enhanced botanical composition, maintained profitable lamb growth rates and reduced GHG emissions intensity. The typical steppe experiment found moderate grazing pressure of ~400 SE grazing days ha–1 (4 SE ha–1 over 100 days) maintained higher lamb growth rates, an average herbage mass >0.5t DM ha–1 that maintained the content of Leymus chinensis above 70% and Artemisia frigida below 10% of the grassland and had the highest level of net carbon sequestration. In the alpine meadow experiment the district average stocking rate of ~16 SE ha–1 (1440 SE grazing days ha–1 over 90 days) was not too high, but extending grazing into the non-growing season had no benefit. The findings of these experiments highlight that many of the benefits to ecosystem services can be achieved with reduced stocking rates which also generate profitable levels of livestock production. In both the desert and typical steppe experiments, the results were optimal when the stocking rates were adjusted to maintain average herbage mass over summer above ~0.5t DM ha–1, whereas herbage mass was higher with the local, conservative stocking rates in the alpine meadow.

scholarly journals Population dynamics of mantis shrimp Harpiosquilla harpax and Oratosquillina sp. in the waters south of Madura Island, Indonesia

2020 ◽  
Vol 21 (4) ◽  
Author(s):  
Yenni Arista ◽  
ZAIRION ◽  
YUSLI WARDIATNO
Keyword(s):  
Population Dynamics ◽  
Population Structure ◽  
Life Span ◽  
Fishery Resource ◽  
Growth Coefficient ◽  
Mantis Shrimp ◽  
Exploitation Rate ◽  
L Value ◽  
Males And Females

Abstract. Ekalaturrahmah YAC, Zairon, Wardiatno Y. 2020. Population dynamics of mantis shrimp Harpiosquilla harpax and Oratosquillina sp. in the waters south of Madura Island, Indonesia. Biodiversitas 21: 1458-1466. Mantis shrimps are a potential fishery resource in Indonesia, but information about their population dynamics in the southern waters of Madura is limited. This study aimed to determine the population structure, growth, life span, and rate of exploitation for two taxa of mantis shrimp (Harpiosquilla harpax and Oratosquillina sp.). The research was conducted from September 2018 to February 2019 in the southern waters of Madura. The results showed that for H. harpax the majority of males caught ranged in length between 132.50 and 139.37 mm while the majority of females were between 153.45 and 160.22 mm. For Oratosquillina sp., the majority of males caught ranged from 84.70 and 89.60 mm while the majority of females were between 89.85 and 95.30 mm. The Growth Coefficient (K) for H. harpax was estimated to be 0.65 per year for males and 0.60 per year for females; while for Oratosquillina sp. the estimates were 0.81 and 0.78 per year, respectively. The L∞ value for H. harpax males was 183.00 mm and for females 250.55 mm, while the L∞ values for Oratosquillina sp. were 112.64 mm for males and 137.02 for females. The life span of H. harpax was estimated at 5 years, while for Oratosquillina sp. it was 4 years. The exploitation rate (E) for H. harpax males and females was 0.65 and 0.67 respectively, while for Oratosquillina sp. it was 0.54 and 0.58. These estimations indicated overexploitation of the resource, particularly in the case of H. harpax.

Using length-frequency data to elucidate the population dynamics of Argulus foliaceus (Crustacea: Branchiura)

Parasitology ◽  
2009 ◽  
Vol 136 (9) ◽  
pp. 1023-1032 ◽  
Author(s):  
N. G. H. TAYLOR ◽  
R. WOOTTEN ◽  
C. SOMMERVILLE
Keyword(s):  
Population Dynamics ◽  
Growth Rates ◽  
Egg Laying ◽  
Frequency Data ◽  
Length Frequency ◽  
Reliable Prediction ◽  
Egg Incubation ◽  
Novel Method ◽  
Argulus Foliaceus ◽  
Length Frequency Data

SUMMARYThis study uses a novel method for discriminating cohorts and investigating the population dynamics of the parasitic crustacean, Argulus foliaceus. Analysis of parasite length-frequency data was carried out in order to elucidate the timings and drivers behind the parasite's life cycle. Up to 6 cohorts of the parasite emerge through the course of 1 year in still-water trout fisheries in England. Recruitment ceases over the winter months; however, 3 cohorts of the parasite over-winter, 2 as eggs and 1 as a hatched stage. The technique, when used in conjunction with temperature data, also allowed for the reliable prediction of growth rates and provided estimates of egg incubation times and the length of hatching periods. These data showed that growth rates increased exponentially between the observed temperatures of 4 to 22°C. The method allowed for the time taken from hatching to egg laying under field conditions to be predicted and produced estimates that were validated against independent laboratory studies on the growth of the parasite.

scholarly journals The Effect of Conspecific Density on Emergence ofLestes bipupillatusCalvert, 1909 (Odonata: Lestidae)

2014 ◽  
Vol 2014 ◽  
pp. 1-3 ◽  
Author(s):  
Ricardo Cardoso-Leite ◽  
Gabriel C. Vilardi ◽  
Rhainer Guillermo-Ferreira ◽  
Pitágoras C. Bispo
Keyword(s):  
Population Dynamics ◽  
Density Dependence ◽  
Social Environment ◽  
Growth Rates ◽  
High Density ◽  
Conspecific Density ◽  
Simulated Environments ◽  
The Social ◽  
Emergence Date

Conspecific density may influence adult recruitment and consequently population dynamics. Several studies have shown the density dependence of larvae growth rates in Odonata. However, few studies studied how conspecific density influence final instar larvae emergence date decisions. Considering that larvae may choose the date of emergence, the present study investigated if density affects larvae choice. For this, we reared eight final instar larvae in individual aquaria and other 24 larvae in aquaria with three larvae each. This way, we simulated environments with low and high larval densities. We then noted the days that larvae took to emerge and compared it between low and high density groups. The results showed that larvae seem to emerge earlier when in high densities (Mann-Whitney,U=10.000,P=0.03). These results support the hypothesis that damselfly last instar larvae may postpone or hasten emergence in response to the social environment and related constraints.

Life history and environmental influences on population dynamics in sockeye salmon

2014 ◽  
Vol 71 (8) ◽  
pp. 1198-1208 ◽  
Author(s):  
Douglas C. Braun ◽  
John D. Reynolds
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Population Growth ◽  
Growth Rates ◽  
Environmental Conditions ◽  
Sockeye Salmon ◽  
Life History Traits ◽  
Relative Importance ◽  
Population Growth Rates ◽  
Habitat Variables

Understanding linkages among life history traits, the environment, and population dynamics is a central goal in ecology. We compared 15 populations of sockeye salmon (Oncorhynchus nerka) to test general hypotheses for the relative importance of life history traits and environmental conditions in explaining variation in population dynamics. We used life history traits and habitat variables as covariates in mixed-effect Ricker models to evaluate the support for correlates of maximum population growth rates, density dependence, and variability in dynamics among populations. We found dramatic differences in the dynamics of populations that spawn in a small geographical area. These differences among populations were related to variation in habitats but not life history traits. Populations that spawned in deep water had higher and less variable population growth rates, and populations inhabiting streams with larger gravels experienced stronger negative density dependence. These results demonstrate, in these populations, the relative importance of environmental conditions and life histories in explaining population dynamics, which is rarely possible for multiple populations of the same species. Furthermore, they suggest that local habitat variables are important for the assessment of population status, especially when multiple populations with different dynamics are managed as aggregates.

scholarly journals Ammonia emissions from a naturally and a mechanically ventilated broiler house in Brazil

2014 ◽  
Vol 18 (11) ◽  
pp. 1179-1185 ◽  
Author(s):  
Luciano B. Mendes ◽  
Ilda F. F. Tinoco ◽  
Nico W. M. Ogink ◽  
Keller S. O. Rocha ◽  
Jairo A. Osorio S. ◽  
...  
Keyword(s):  
Ventilation System ◽  
Stocking Density ◽  
Emission Factors ◽  
Ammonia Emission ◽  
Mechanically Ventilated ◽  
Nh3 Emission ◽  
Modeling Process ◽  
Tropical Conditions ◽  
Ventilation Rates ◽  
Broiler House

This study was conducted with the aim of monitoring NH3 emissions from a mechanically and a naturally ventilated broiler house (MVB and NVB, respectively) and calculate their ammonia emission factors (fNH3). Bird stocking density was 13.5 and 11.1 birds m-2 for the MVB and NVB, respectively. The marketing age was 43 days and bedding consisted of dried coffee husks in its first time of use. Ventilation rates were calculated with the metabolic carbon dioxide mass balance method. Values of fNH3 were 0.32 ± 0.10 and 0.27 ± 0.07 g bird-1 d-1 for the MVB and NVB, respectively, and are in agreement to what was presented in other studies performed under similar conditions. The fNH3 estimated on yearly basis was 58 g bird-place-1 year-1. It was concluded that the different types of ventilation system between the studied broiler barns did not significantly affect emissions in the modeling process. The results obtained help providing reliable methodology for the determination of a solid database on NH3 emission factors for tropical conditions that can be used for future inventories, when performed in a sufficient number of barns that is representative for the Brazilian scenario.

Effect of time of joining and rate of stocking on the production of Corriedale ewes in southern Victoria. 2. Survival and growth of lambs

1974 ◽  
Vol 14 (69) ◽  
pp. 434 ◽  
Author(s):  
PA Kenney ◽  
IF Davis
Keyword(s):  
Growth Rate ◽  
Birth Weight ◽  
Milk Production ◽  
Growth Rates ◽  
Stocking Rate ◽  
Survival And Growth ◽  
Single Birth

A study of the survival and growth of lambs was made over a three year period (1968 to 1970) on a flock of 540 ewes grazing annual pasture at Werribee, Victoria. Ewes were stocked at three rates (5, 7 1/2 and 10 ha-1) and lambed between July 6 and August 20 or between September 10 and October 29 each year. Observations were made on the same ewes each year. Rate of stocking had no effect on the birth weight of lambs but single-birth lambs born in September were lighter than those born in July. More twins were born in September than in July and a smaller proportion of lambs born survived from the September than from the July lambing. Of the lambs born to ewes stocked at 10 ha-1 in 1968 and 1969 a smaller proportion survived than of the lambs born to ewes stocked at 5 ha-1. The growth rate of lambs born in July was constant between birth and weaning at 12 weeks of age but declined as rates of stocking increased. When the lambs born in September were about eight weeks old the pastures matured and growth rates of lambs declined and at weaning liveweights of lambs from plots stocked at different rates were similar. Lambs born in July on plots stocked at 5 and 79 ewes ha-1 were as much as eight kilograms heavier at weaning than the lambs born in September at equivalent rates of stocking. Neither rate nor time of onset of milk production was significantly affected by stocking rate.

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