The aim of the study was to estimate the contribution of group to phenotypic variance of daily gain on different intervals. The focus was on data structure and differences of variance components ...estimated with and without effect of the social group. Growth of 806 boars from 443 litters was obtained during the field test in nucleus herd of Pietrain breed. A group was defined as pen mates. Most frequently, the group was formed from 6 and 7 boars. Data sets were prepared with SAS Software, variance components were estimated using VCE-6. The results showed the significant contribution of the group to phenotypic variance of daily gain. Inclusion of the effect of social group reflected in lower heritability and the smaller contribution of common litter environment. Further analysis revealed different contributions of components to phenotypic variance of growth rate on different intervals. The proportion of variation caused by common litter environment was larger on the interval from ±32.0 kg to ±48.8 kg of body weight (22%), compared to interval from ±39.6 kg to ±104.1 kg, explaining 1% of phenotypic variation, that could be the consequence of less defined pretest environment. The social group explained 6% of phenotypic variance for daily gain on interval from ±39.6 kg to ±104.1 kg of body weight, however, the contribution was larger on the interval from ±32.0 kg to ±48.8 kg (23%). The results confirmed the group as an environmental component, causing more variation in daily gain shortly after group formation (±32.0 kg), when a hierarchy is established, and later after its set, the contribution decreases
The objective of the study was to analyze lifetime production data for two Slovenian locally adapted dairy breeds: Slovenian Saanen goat (334) and Slovenian Alpine goat (1105) and for the dairy type ...of Dreznica goat (141) which is the only Slovenian autochthonous goat breed. Dataset included records from 54 farms. Data for does born after 2002 have been obtained from the database of the National selection program for small ruminants, collected by the ICAR standards. The contribution of farm to phenotypic variance was estimated. Data was analyzed by MIXED procedure in SAS/STAT. The results showed significant effect of breed, farm and year of culling on all traits studied, except the effect of breed on completed lactations in lifetime and number of liveborn kids. The lifetime milk yield was higher in Slovenian Alpine goat compared to Slovenian Saanen goat by 413.26±172.52 kg. The difference in lifetime protein yield between Slovenian Alpine goat and Slovenian Saanen goat amounted to 11.76±5.21 kg. Dreznica goat did not differ in lifetime milk production and protein yield compared to both intensive goat breeds. Dreznica goat yielded about 25.50±5.21 kg more fat in lifetime compared to Slovenian Saanen goat. However, compared to Slovenian Alpine goat the difference was not significant. Comparison of Slovenian Saanen goat and Slovenian Alpine goat revealed higher lifetime fat yield of Slovenian Alpine goat by 13.28±5.21 kg. The results suggested reasonably good performance and adaptation of the autochthonous breed Dreznica goat in local agro climatic conditions.
Chickens of the Slovenian commercial Prelux-bro line were divergently selected over 34 generations for high and low BW at 8 wk of age. The aim of the study was to estimate responses to selection with ...a nonlinear model. Estimates of BW for each generation were provided by the mixed model. For fitting generation means against generation or cumulative selection differential, an exponential model was used. Estimates of realized heritability over generations were derived from regression of the response on cumulative selection differential. After 34 generations, the lines differed by approximately 2,220 g for males and 1,860 g for females. Estimates for a selection limit in the high line were 2,598.4 and 2,144.1 g, for males and females, respectively. A selection limit was not reached in the low line. Half of the selection response was obtained after approximately 6 to 8 generations in the high line and 20 to 28 generations in the low line. Estimated realized heritability decreased over generations. Heritability was larger for females than males and reduction of heritability was more rapid in the high line than in the low line. Genetic SD decreased over generations. Phenotypic SD increased over generations in the high line, but was constant in the low line in the initial 22 generations and decreased thereafter. According to the good fit of the nonlinear model and informative parameter estimates, the results confirmed the usefulness of the nonlinear model for analyzing responses to long-term selection.
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.
Počasna konvergenca je eden največjih problemov uporabe metode Monte Carlo z Markovimi verigami (McMC) za mešane modele na področju genetike in selekcije domačih živali. Slaba konvergenca je v veliki meri posledica visoke posteriorne korelacije med komponentami variance in rešitvami za ravni pripadajočih vplivov. Predstavljamo enostavno reparametrizacijo običajnega modela, ki izboljša lastnosti metode McMC in daje enake posteriorne porazdelitve parametrov modela kot standardni pristop. Reparametrizacija temelji na standardizaciji hierarhičnih (naključnih) vplivov v modelu, kar posledično spremeni posteriorne korelacije med parametri. Oba pristopa smo primerjali na večjem setu simuliranih podatkov. Rezultati kažejo, da reparametrizacija vodi do bolj učinkovitih metod McMC vzorčenja in je nekajkrat bolj učinkovita za analizo lastnosti z nizko heritabiliteto.
Proteins extracted from microalgae for food, personal care products and cosmetics must be of high purity, requiring solvent-free extraction techniques despite their generally considerably lower ...protein yield and higher energy consumption. Here, three such approaches for green extraction of proteins from
Chlorella vulgaris
were evaluated: ultrasound, freeze-thawing, and electroporation; chemical lysis was used as positive control (maximal achievable extraction), and no extraction treatment as negative control. Compared to chemical lysis, electroporation yielded the highest fraction of extracted protein mass in the supernatant (≤27%), ultrasound ≤24%, and freeze-thawing ≤15%. After a growth lag of several days, electroporated groups of algal cells started to exhibit growth dynamics similar to the negative control group, while no growth regeneration was detected in groups exposed to ultrasound, freeze-thawing, or chemical lysis. For electroporation as the most efficient and the only non-destructive among the considered solvent-free protein extraction techniques, simultaneous extraction of intracellular algal lipids into supernatant was then investigated by HPLC, proving relatively low-yield (≤7% of the total algal lipid mass), yet feasible for glycerides (tri-, di-, and mono-) as well as other fatty acid derivatives. Our results show that electroporation, though lower in extraction yields than chemical lysis or mechanical disintegration, is in contrast to them a technique for largely debris-free extraction of proteins from microalgae, with no need for prior concentration or drying, with feasible growth regeneration, and with potential for simultaneous extraction of intracellular algal lipids into the supernatant.
PDF
