Agris category codes: U10
COBISS
1.01 Language: English
Simple
reparameterization to improve convergence in linear mixed models
1,
Tina FLISAR, Jose Carlos MARTÍNEZ-ÁVILA, Luis Alberto
GARCÍA-CORTÉS
1 Univ. of Ljubljana, Biotechnical Fac., Dept. of Animal
Science, Groblje 3, SI-1230 Domžale, Slovenia,, Ph.D.
ABSTRACT
Slow convergence
and mixing are one of the main problems of Markov chain Monte Carlo (McMC)
algorithms applied to mixed models in animal breeding. Poor convergence is
to a large extent caused by high posterior correlation between variance
components and solutions for the levels of associated effects. A simple
reparameterization of the conventional model for variance component
estimation is presented which improves McMC sampling and provides the same
posterior distributions as the conventional model. Reparameterization is
based on the rescaling of hierarchical (random) effects in a model, which
alleviates posterior correlation. The developed model is compared against
the conventional model using several simulated data sets. Results show that
presented reparameterization has better behaviour of associated sampling
methods and is several times more efficient for the low values of
heritability.
Agris category codes:
L01
COBISS
1.01
Language: English
Multivariate analysis of
phenotypic differentiation in Bunaji and Sokoto Gudali cattle
1,
Kingsley Omogiade IDAHOR, Hadiza Salihu HARUNA, Matthew
WHETO, Samuel AMUSAN
1Nasarawa State Univ., Fac. of Agriculture, Dept. of
Animal Science, Keffi, Shabu-Lafia Campus, P.M.B. 135, Lafia, Nigeria
ABSTRACT
The study aimed at examining morphometric differentiation in two Nigerian
breeds of cattle using multifactorial discriminant analyses. Ten
morphological traits (withers height, rump height,chest circumference, body
length, face length, tail length, rump length, head width, rump width and
shoulder width) of 224 Bunaji and 87 Sokoto Gudali cattle were measured. The
animals, which were aged 2.5−3.6 years, were subjected to extensive
management system. The linear type traits of Sokoto Gudali cattle were
significantly (P<0.05) higher than those of their Bunaji counterparts,
with the exception of body length and face length respectively. The stepwise
discriminant analysis gave a better resolution as only three variables, rump
width, withers height and face length were more discriminating in separating
the two cattle breeds. The Mahalanobis distance (7.19) between the two
cattle populations was high and significant, which is an indication that
they belong to genetically different groups. This was complemented by the
result of the Nearest Neighbour Discriminant Analysis, where 85.48% of
Bunaji cattle were classified into their source population while 96.55% of
their Sokoto Gudali counterparts were correctly assigned into their source
genetic group. The present phenotypic information will be the basis for the
establishment of further characterization, conservation and selection
strategies for the two Nigerian breeds of cattle.
Agris
category codes:
P30, P34 COBISS
1.01
Language: English
Antibiotic-resistant soil
bacteria in high-altitude (5000–6000 m)
soils of the Himalaya
1
1Univ. of Ljubljana,
Biotechnical Fac., Dept. of Animal Science, Groblje 3, SI-1234 Domžale,
Slovenia, Ph.D.
ABSTRACT
In this study, low-carbon soils collected from an
altitude transect from 5000 m to 6000 m were adopted as a simple model
system with lower interaction complexity. This could help disentangle the
basic environmental factors shaping the abundance and distribution of
expressed resistance traits in culturable portion of fast growing
heterotrophic strains. Improved plate counts were performed at 4°C using
0.01 diluted nutrient broth supplemented with cold soil extract as a general
media and additionally supplemented with antibiotics Ampicillin,
Erythromycin, Kanamycin and Tetracyclin. A number of colonies (500) isolated
from six locations were also tested separately for their antibiotic
resistance. The results show that these high-altitude cold soils contained
bacterial populations culturable at 4°C in the range of 106 cells / g that
were resistant to the four antibiotics and their various combinations tested
in this study. The highest prevalence of resistance was observed in
vegetated soils, whereas almost two orders of magnitude lower abundance of
resistant cells was cultured from barren soils. Redundancy analysis showed
that vegetation, soil carbon and pH were successful in explaining the
interaction between environmental parameters and various culturable
fractions of cold soil bacteria used in this study.
Agris
category codes:
P10, T01
COBISS
1.01
Language: English
Methylmercury inhibits
growth and induces membrane changes in
Pseudomonas putida
1, Mirjana BISTAN, Maša ZOREC,
Romana MARINŠEK LOGAR
1 Univ. of Ljubljana, Biotechnical Fac., Dept. of Animal
Science, Groblje 3, SI-1230 Domžale, Slovenia
ABSTRACT
A bacterial model system (Pseudomonas putida DSM 50026)
was used in this research to assess toxicity of the environmentally relevant
concentrations of mercury species (MeHg and Hg(II)) that represent important
pollutants of aquatic ecosystems at sites of industrial or mining
activities. In addition to direct monitoring of bacterial growth, we also
analyzed fatty acid profiles of exposed and non-exposed cultures to
determine possible toxic effects manifested on membrane level. The results
showed that exposure of P. putida to Hg(II) in concentrations of 0.2–200
µg/L did not have any significant effects on growth nor fatty acid
composition of exposed bacterial culture. On the other hand, when bacteria
were exposed to up to 1600-times lower concentrations of MeHg (0.12–12.5
µg/L), growth inhibition as well as significant changes in fatty acid
composition were detected. Observed adaptive membrane changes due to MeHg
exposure were similar to those associated with responses to organic solvents
and some other membrane-disrupting compounds.
Agris category codes:
Q04
COBISS
1.01
Language: English
Variations in the fatty
acid composition and nutritional value of Adriatic sardine (Sardina
pilchardus Walb.) through the fishing season [1]
Monika MARIN 1, Tomaž POLAK, Lea GAŠPERLIN,
1 Droga
Kolinska, Food Industry, d.d., Kolinska 1, SI-1000 Ljubljana, Slovenia
ABSTRACT
We investigated the chemical composition, in terms of
water, protein, ash, total fat and fatty-acid composition, of sardine meat,
and estimated its nutritional value. The samples originated from Adriatic
sardines (Sardina pilchardus Walb.) that were collected in the north
Adriatic Sea through the winter, spring, summer and autumn seasons. The
content of 20 fatty acids was determined by in-situ transesterification and
capillary column gas-liquid chromatography, using nonadecanoic acid (19:0)
as internal standard. The mean contents of the sardine meat were: 70.8%
water, 21.0% protein, 2.5% ash and 6.4% fat. For the fatty-acid composition,
18.0% were mono-unsaturated, 42.6% polyunsaturated and 39.8% saturated. The
total-fat content increased through the year, from winter to autumn (0.69 to
18.15 g/100 g meat). The fatty-acid composition in the sardine meat varied
significantly, with the levels of the polyunsaturated fatty acids (4.6 g/100
g meat), and especially eicosapentaenoic acid (20:5n-3, 0.98 g/100 g meat)
and docosahexaenoic acid (22:6n-3, 1.9 g/100 g meat), being the highest in
autumn, before spawning. The n-6/n-3 ratio (0.13) and P/S ratio (7.6) show
that sardine meat can and should be included in a balanced human diet.
Considering the recommended daily intake of n-3 polyunsaturated fatty acids
is 0.45 g per day for a healthy population, this would be consumed as 10 g
sardine meat collected in the autumn or 100 g sardine meat collected in the
winter.
Key words: human nutrition / food / fish / Adriatic
sardine / Sardina pilchardus Walb. / composition / fatty acids / nutritional
value / season
[1]
This article is part of a M.Sc. thesis ‘ Lipid
composition and sensory quality of the adriatic sardine (Sardina
pilchardus) in different seasons ‘, issued by Monika Marin,
supervisor Prof. Božidar Žlender, Ph.D.
Agris category codes:
L01
COBISS
1.01
Language: English
Foraging
behaviour of
sheep at pasture with different types of vegetation in a paddock [1]
1,
Danijela BOJKOVSKI, Ivan ŠTUHEC, Dragomir KOMPAN
1 Univ.
of Ljubljana, Biotechnical Fac., Dept. of Animal Science, Groblje 3, SI-1230
Domžale, Slovenia, Assist., Ph.D., M.Sc.
ABSTRACT
This experiment was designed to study the foraging
behaviour of ewes on a pasture with paddocks with three different types of
vegetation, herbaceous (n = 3), woody (n = 2), and semi open (n = 1). Forty
sheep were bred on a farm in the Karst region of Slovenia. Ten sheep were
focally observed during day light (5 a.m.–9 p.m.). Ewes were observed for 2
days in each paddock with one rotation, so 12 days in total. Grazing time,
circadian rhythm of grazing, drinking frequency, and frequency of salt
consumption were the observed behaviours. On average, ewes grazed for 10.5
hours a day (mean ± SD = 626.2 ± 47.2 min), with a significant difference
between individual variation (P<0.001). Sheep grazed the most in
herbaceous paddocks (P<0.001), with lower yet similar levels observed in
woody and semi open paddock. The frequency of drinking and salt consumption
was low. Individual grazing sheep would drink slightly less than once per
day, while consuming salt on average 1.25 times per day. Drinking frequency
was the highest in the semi open paddock with some trees and bushes, whereas
salt consumption was most frequently observed in the woody paddocks.
[1]
The article is a part of graduation thesis issued by
Danijela Tomažič, supervisor Prof. Ivan Štuhec, Ph.D., co-advisor
Prof. Dragomir Kompan, Ph.D.
Agris category codes:
M40
COBISS
1.01
Language: English
Fluctuating
asymmetry in
diploid female and sterile triploid rainbow trout (Oncorhynchus
mykiss)
1,
Klavdija STRGAR
1 Univ.
of Ljubljana, Biotechnical Fac., Dept. of Animal Science, Groblje 3, Domžale,
SI-1230, Slovenia, Assist. Prof., Ph.D., M.Sc.
ABSTRACT
Viability of an organism and possibility to survive in
natural environment could be judged by the magnitude of fluctuating
asymmetry (FA) which is defined as random deviation from perfect symmetry of
an organism. In order to estimate if there is the difference in FA between
diploid female and sterile triploid rainbow trout (Oncorhynchus mykiss) the
number of rays in pelvic and pectoral fins was determined on both sides of
body in 150 individuals from two populations which were of the same genetic
origin and were reared under same farm conditions. Units of asymmetry were
determined as the absolute value of difference between counts on both sides
of body. Results indicate that diploids exhibit larger FA than triploids in
both traits; however the difference between both populations is
statistically significant only if the number of units of asymmetry for both
traits for each fish is summed up. The need to estimate the viability of
these two populations on the basis of other traits is discussed and the
necessity to use the metric traits to determine FA is stressed out.
Estimation of
dispersion
parameters for linear type traits in the Haflinger horses
1,
Janez RUS, Milena KOVAČ, Špela MALOVRH
1 Univ.
v Ljubljani, Biotehniška fak., Odd. za zootehniko, Groblje 3, SI-1230
Domžale, Sovenija, Assist.
ABSTRACT
The covariance components for exterior traits were
estimated on Haflinger horses in Slovenia. There were 3371 data included in
the database. Data from 600 animals (15 stallions and 585 mares) with known
pedigree were analysed. For each horse, at most ten traits were scored and
nine traits were measured. The fixed part of the model included only the
year when horse was scored or measured and animal was treated as random
effect. Genetic and environmental parameters for exterior traits were
estimated by the restricted maximum likelihood method (REML) as implemented
in the program package VCE. To make matrices positive definite we used a
statistic method commonly known as ’bending’. Heritabilities for the scored
traits were estimated between 0.40 for front body part and 0.78 for the
breed type. For measured traits the heritabilities were between 0.20 for
chest depth and 0.62 for withers height (measuring stick). Genetic
corelations were in most cases positive. The highest genetic corelation for
scored traits was 0.92 between total score and rear body part. There was no
corelation betwen breed type and front legs. Genetic corelations for
measured traits were from 0.38 between body lenght and chest size to 0.95
betwen withers hight measured with stick and measured with tape.
