Frank Siewerdt
University of Maryland, College Park
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Frank Siewerdt.
Poultry Science | 2010
B. A. Ventura; Frank Siewerdt; Inma Estevez
Deterioration of footpad and hock condition and increased stress are important welfare concerns in high-density broiler production. It has been argued that environmental enrichment may help address these issues. We hypothesized that increasing environmental complexity by providing access to barrier perches across a range of densities should improve footpad and hock health, reduce leg fluctuating asymmetry (FA), and mitigate fear in broilers without compromising bird performance. In this study, 2,088 one-day-old broiler chicks were randomly assigned to one of the following barrier and density treatment combinations over 4 replications: simple barrier, complex barrier, or no barrier (control) and low (8 birds/m(2)), moderate (13 birds/m(2)), or high (18 birds/m(2)) density. In wk 7, data were collected on average tibia width and length, FA of tibia width and tibia length, footpad and hock lesions, tonic immobility, feed conversion, final BW, and mortalities. Broilers at higher densities had more severe footpad (P < 0.0001) and hock lesions (P < 0.0001). Their tibias were also longer (P < 0.0001) and less symmetric in length (P < 0.05). The tibias of birds in complex barrier pens were more symmetric in length compared with controls (P < 0.05). Barrier treatment had no effect on hock lesions, although there was a trend for simple barriers to reduce the severity of footpad lesions compared with the control treatment (P = 0.089). Birds kept in simple barrier pens were more susceptible to tonic immobility induction (P < 0.05). Final BW, feed conversion, and mortalities were neither affected by stocking density nor by barrier inclusion. In conclusion, this study shows a negative effect of high density on broiler footpad health and FA. Although barrier perches did not appear to reduce fearfulness, the improvement in footpad health suggests that simple barriers may provide key welfare benefits to broiler chickens.
Journal of the American Geriatrics Society | 2011
Julia H. Engel; Frank Siewerdt; Robert T. Jackson; Ucheoma Akobundu; Carolyn Wait; Nadine R. Sahyoun
OBJECTIVES: To examine the associations between hardiness (defined as the ability to manage stress), depression, and emotional well‐being and appetite in older adults.
PLOS ONE | 2012
B. A. Ventura; Frank Siewerdt; Inma Estevez
Restriction of behavioral opportunities and uneven use of space are considerable welfare concerns in modern broiler production, particularly when birds are kept at high densities. We hypothesized that increased environmental complexity by provision of barrier perches would help address these issues by encouraging perching and enhancing use of the pen space across a range of stocking densities. 2,088 day-old broiler chicks were randomly assigned to one of the following barrier and density treatment combinations over four replications: simple barrier, complex barrier, or control (no barrier) and low (8 birds/m2), moderate (13 birds/m2), or high (18 birds/m2) density. Data were collected on focal birds via instantaneous scan sampling from 2 to 6 weeks of age. Mean estimates per pen for percent of observations seen performing each behavior, as well as percent of observations in the pen periphery vs. center, were quantified and submitted to an analysis of variance with week as the repeated measure. Barrier perches, density and age affected the behavioral time budget of broilers. Both simple and complex barrier perches effectively stimulated high perching rates. Aggression and disturbances were lower in both barrier treatments compared to controls (P<0.05). Increasing density to 18 birds/m2 compared to the lower densities suppressed activity levels, with lower foraging (P<0.005), decreased perching (P<0.0001) and increased sitting (P = 0.001) earlier in the rearing period. Disturbances also increased at higher densities (P<0.05). Use of the central pen area was higher in simple barrier pens compared to controls (P<0.001), while increasing density above 8 birds/m2 suppressed use of the central space (P<0.05). This work confirms some negative effects of increasing density and suggests that barrier perches have the potential to improve broiler welfare by encouraging activity (notably by providing accessible opportunities to perch), decreasing aggression and disturbances, and promoting more even distribution of birds throughout the pen space.
Journal of Andrology | 2011
Wendy K. Kiso; Janine L. Brown; Frank Siewerdt; Dennis L. Schmitt; Deborah Olson; Elizabeth G. Crichton; Budhan S. Pukazhenthi
Artificial insemination plays a key role in the genetic management of elephants in zoos. Because freshly extended semen is typically used for artificial insemination in elephants, it has become imperative to optimize conditions for liquid storage and semen transport. The objectives of this study were to examine the interactions between different extenders and storage temperatures on sperm total motility, progressive motility, and acrosomal integrity in Asian (Elephas maximus) and African (Loxodonta africana) elephants. Ejaculates were collected by rectal massage, diluted using a split-sample technique in 5 semen extenders: TL-Hepes (HEP), Modena (MOD), Biladyl (BIL), TEST refrigeration medium (TES), and INRA96 (INR), maintained at 35°C, 22°C, or 4°C. At 0, 4, 6, 12, and 24 hours, aliquots were removed and assessed for sperm total motility, progressive motility, and acrosomal integrity. After 24 hours of storage, African elephant spermatozoa exhibited greater longevity and higher values in sperm quality parameters compared with those of Asian elephants. In both species, semen storage at 35°C resulted in a sharp decline in all sperm quality parameters after 4 hours of storage, whereas storage at 22°C and 4°C facilitated sperm survival. In Asian elephants, MOD and HEP were most detrimental, whereas BIL, TES, and INR maintained motility up to 12 hours when spermatozoa were cooled to 22°Cor4°C. In African elephants, there were no differences among extenders. All media maintained good sperm quality parameters at 22°C or 4°C. However, although MOD, BIL, and INR were most effective at lower temperatures, HEP and TES maintained sperm motility at all storage temperatures. This study demonstrated sperm sensitivity to components of various semen extenders and storage temperatures and offers recommendations for semen extender choices for liquid semen storage for both Asian and African elephants.
North American Journal of Aquaculture | 2011
Kathryn M. Dorsey; H. David Guthrie; G.R. Welch; Jerre W. Mohler; Daniel D. Theisen; Frank Siewerdt; Bryan T. Vinyard; L. Curry Woods
Abstract Short-term storage trials were conducted with semen of Atlantic sturgeon Acipenser oxyrinchus collected from a total of nine wild males during the 2008 and 2009 spawning seasons on the Hudson River. Semen samples were kept refrigerated (4 ± 1°C) and stored in different gaseous atmospheres and storage extenders. The gaseous environments included oxygen, nitrogen, and air, while the extender treatments included modified Tsvetkova (MT), Park and Chapman (PC), and undiluted. Analyses of four response variables—percent viable sperm (viability), percent motile sperm (motility), curvilinear velocity (VCL), and ATP content—were determined on the day of arrival in the laboratory and then every other day for 7 d in 2008 and 21 d in 2009. The experiments were conducted in a split-split-plot design to examine dilution treatment, gas atmosphere, and repeated measures across days, and linear analyses of covariance models were fit to the data after appropriate transformation. Storage of sperm in an oxygen atmos...
Brazilian Archives of Biology and Technology | 2010
Jayme Aparecido Povh; Ricardo Pereira Ribeiro; Rodolfo Nadez Sirol; Danilo Pedro Streit; Heden Luiz Marques Moreira; Frank Siewerdt; Nelson Mauricio Lopera-Barrero; Claudete Aparecida Mangolin; Lauro Vargas
The objective of this study was to evaluate the genetic diversity and the parental contribution of Piaractus mesopotamicus in the production of offspring in the semi-natural system of reproduction. Twenty parental fishes (eleven males and nine females) and the total of 100 larvae were evaluated by microsatellite marker. The parents and offspring had thirty-one alleles and heterozygosity of 0.550 and 0.563, respectively. The females were fertilised by two up to six males while the males fertilised three up to five females. The contribution of the females and males to the offspring were 66.6 and 58%, respectively. Such results indicated no loss in the genetic variability in the offspring, and the parents had multiple paternity and reasonable contribution to the offspring production.
Revista Brasileira De Zootecnia | 2009
José Acélio Silveira da Fontoura Júnior; Frank Siewerdt; Nelson José Laurino Dionello; Marcio Nunes Corrêa
A dynamic mathematical model was developed to describe the reproductive process in beef cattle production systems and to simulate individual cow reproductive performance while generating results for the herd, based on the body condition score (BCS) at calving and age at sexual maturity. The model is empiric and dynamic, containing deterministic and stochastic elements. The model was developed based on the relationship between BCS and postpartum interval for lactating cows; for heifers and non-lactating cows, the conception rate was based on the probability to conceive; for heifers, body weight and age at puberty were the limiting factors. The model has two forms of reading inputs: from a parturition report generated by software or from raw data provided by the user. Input data are considered averages, except for those defining the reproductive season. The model assigns a standard deviation to each variable, with normal distribution. The final output is in the form of a report providing the annual amount of kg of weaned calves per cow, among other information. Inputs may be freely changed to evaluate the impact of new parameters on the output. This model contributes to a greater understanding of the production system studied and allows simulation of the reproductive performance of beef cows at calving from their BCS. Once validated, it is envisioned that the model will be a valuable tool to aid decision-making.
ICAN: Infant, Child, & Adolescent Nutrition | 2012
Catherine J. Klein; Tova G. Jacobovits; Frank Siewerdt; Leila T. Beker; Mark A. Kantor; Nadine R. Sahyoun; Irene Chatoor
Eating disorders among young children are not well characterized. Diet and growth data were collected from toddlers (1-3 years old) at the time of diagnosis of infantile anorexia (IA) and up to 1 y...
Revista Brasileira De Zootecnia | 2010
José Acélio Silveira da Fontoura Júnior; Frank Siewerdt; Nelson José Laurino Dionello; Marcio Nunes Corrêa; Carlos André de Oliveira da Silva
This work was carried out with the goal of demonstrating and performing internal evaluation of the mathematical model developed to describe the reproductive performance in production systems and to simulate reproductive performance of beef cows from the body condition score at calving (BCSAC). This model is based on the relationship between BCSAC and the interval between calving and conception (ICC) for lactating cows; for heifers and empty cows at conception, it was based on the probability of occurrence. For internal evaluation of the model, it was used the methodologies of verification and calibration. The use of technique of variation of input data was done based through the construction of scenarios by changing BCSAC, starting date of the reproductive season (SDRS), average date of calving (ADC), and average daily weight gain from birth to weaning (ADWGBW). These scenaries also served for demonstration of the model. Through calibration, it was chosen new standard deviations for the following variables: gestation period, ADWGBW and average birth date (ABD). Tests for degenerescence and independence of seeds generating random numbers, after calibration, showed coherence of the model in generating randomness for the variables being studied. Variation on the input data showed effectiveness of the model to simulate the dynamics of reproduction systems. Nevertheless, adjustments in conception rate of primiparous females are needed for the model to generate values that are compatible with reality.This work was carried out with the goal of demonstrating and performing internal evaluation of the mathematical model developed to describe the reproductive performance in production systems and to simulate reproductive performance of beef cows from the body condition score at calving (BCSAC). This model is based on the relationship between BCSAC and the interval between calving and conception (ICC) for lactating cows; for heifers and empty cows at conception, it was based on the probability of occurrence. For internal evaluation of the model, it was used the methodologies of verification and calibration. The use of technique of variation of input data was done based through the construction of scenarios by changing BCSAC, starting date of the reproductive season (SDRS), average date of calving (ADC), and average daily weight gain from birth to weaning (ADWGBW). These scenaries also served for demonstration of the model. Through calibration, it was chosen new standard deviations for the following variables: gestation period, ADWGBW and average birth date (ABD). Tests for degenerescence and independence of seeds generating random numbers, after calibration, showed coherence of the model in generating randomness for the variables being studied. Variation on the input data showed effectiveness of the model to simulate the dynamics of reproduction systems. Nevertheless, adjustments in conception rate of primiparous females are needed for the model to generate values that are compatible with reality.
Applied Animal Behaviour Science | 2011
Taylor Callicrate; Frank Siewerdt; Elizabeth Koutsos; Inma Estevez
Collaboration
Dive into the Frank Siewerdt's collaboration.
José Acélio Silveira da Fontoura Júnior
Universidade Federal de Pelotas
View shared research outputsNational Council for Scientific and Technological Development
View shared research outputs