Institute of Animal Science

Prague, Czech Republic

Institute of Animal Science

Prague, Czech Republic

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Consumer preference for poultry meat from free-range birds is not justified by scientific evidence. Inconsistency in results among studies on the effects of access to pasture on performance, carcass composition, and meat quality has led to a meta-analysis to quantify effects. After identification of studies where response variables were directly compared between birds with and without access to pasture, standardized effect sizes were used to calculate differences. The effect size for growth combined according to a fixed effect model did not present heterogeneity (P = 0.116). However, with feed intake and feed efficiency, variability among studies (heterogeneity with P-values of below 0.10) was influenced by more than sampling error. Carcass yield was the only carcass component that showed heterogeneity (P = 0.008), whereas numerous response variables related to meat quality were not homogenous. The use of subgroup analysis and meta-regression to evaluate the sources of heterogeneity was limited by ill-defined explanatory variables and few values available within response variables. Consequently, between-study variability was accounted for by use of random effects models to combine effect sizes. According to these, few response variables were influenced by pasture access. Fat concentrations in breast (mean effect size = -0.500; 95% CI = -0.825 to -0.175; 11 studies; 14 comparisons), thigh (mean effect size = -0.908; 95% CI = -1.710 to -0.105; 4 studies; 5 comparisons) and drum (mean effect size = -1.223; 95% CI = -2.210 to -0.237; 3 studies; 3 comparisons) muscles were decreased in free-range birds. Access to pasture increased (P < 0.05) or tended to increase (P < 0.10) protein concentrations in the respective commercial cuts. It is concluded that factors other than enhanced meat quality could be responsible for consumer preference for meat from free-range poultry. © 2014 Poultry Science Association Inc.


Sales J.,Institute of Animal Science
Biological Trace Element Research | Year: 2013

Pharmacological dietary zinc (Zn) concentrations of 1,000 to 3,000 mg/kg diet from Zn oxide have been found to increase growth in post-weaning pigs. However, results were inconsistent among studies. A frequentist meta-analysis, in which effects were numerically described with standardized effect sizes (Hedges's g), was conducted in order to identify and quantify the responses in average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G/F) in post-weaning pigs upon dietary Zn supplementation from Zn oxide. The inability of independent continuous variables to explain significant heterogeneity obtained with fixed effect models necessitated the use of random effects models to calculate summary statistics. Dietary Zn supplementation increased (P < 0.05) ADG (mean effect size = 1.086, 95 % confidence intervals = 0.905-1.266, 26 studies, 72 comparisons), ADFI (mean effect size = 0.794, 95 % confidence intervals = 0.616-0.971, 25 studies, 71 comparisons), and G/F (mean effect size = 0.566, 95 % confidence intervals = 0.422-0.710, 24 studies, 70 comparisons). Zinc oxide provided a feasible alternative to in-feed antibiotics to improve growth in post-weaning pigs, and its reduction in diets due to potential environmental pollution will have to be negated by alternative feed additives and management strategies in order to prevent economic losses. © 2013 Springer Science+Business Media New York.


Sales J.,Institute of Animal Science
Meat Science | Year: 2014

After an extensive literature search, meta-analytic techniques (fixed effect, random effects and hierarchical Bayesian models) were applied to numerically describe sizes and precision of effects caused by castration of intact rams on several performance, carcass and meat quality response variables. According to random effects models, rams presented greater (P<. 0.05) average daily gain, loin muscle area (leaner carcasses) and instrumental meat tenderness (more tough), with lower feed conversion ratios, dressing percentages and backfat thickness (less carcass fat) compared to castrates. These results could be applied in further strategies on the use of castration in male sheep. © 2014 Elsevier Ltd.


Sales J.,Institute of Animal Science
Animal Feed Science and Technology | Year: 2011

Inconsistent results of the effects of dietary betaine supplementation on important economic carcass characteristics of finishing pigs have been reported. This has motivated a quantitative meta-analysis that accounted for variability among experiments. Through an extensive literature search data have been identified to evaluate the effects of dietary betaine supplementation on average daily feed intake (ADFI; 11 experiments, 18 comparisons), average daily gain (ADG; 13 experiments, 21 comparisons), backfat thickness (BFT; 10 experiments, 13 comparisons), dressing proportion (DP; 7 experiments, 10 comparisons), feed conversion ratio (FCR; 12 experiments, 18 comparisons), longissimus dorsi muscle area (LMA; 9 experiments, 13 comparisons), proportion carcass lean (PCL; 7 experiments, 10 comparisons) and tenth rib fat thickness (TRFT; 7 experiments, 10 comparisons). Statistical analyses included: (1) fixed and random effects models to calculate summary statistics for standardised effect sizes (Hedges's g) of the difference between control and betaine-fed pigs; (2) meta-regression to evaluate the sources of heterogeneity of responses; (3) the assessment of possible publication bias. Dietary betaine supplementation had no influence (P > 0.05) on ADG. However, feed per unit of weight gain significantly decreased (mean effect size of -0.361) in betaine-fed pigs. Whereas dressing proportion was increased (mean effect size of 0.358; P < 0.05) by betaine supplementation, BFT was decreased with a mean effect size of -0.286. The occurrence (P < 0.10) of heterogeneity showed that the effects of betaine varied from experiment to experiment for ADFI, PCL, LMA and TRFT. With ADG and TRFT some of this variability could be explained by a negative relationship (P < 0.10) between effect size and level of betaine supplementation. Existing tests could not detect evidence of any possible publication bias. This study presented conclusive results that betaine supplementation of diets for finishing pigs decreased carcass characteristics typically used as indicators of carcass fatness. © 2011 Elsevier B.V.


Despite the increased use of dry active Saccharomyces cerevisiae yeast supplementation in ruminant feeding, inconsistent results among studies hamper the prediction of its effects on animal performance. A meta-analysis has been conducted to quantify the magnitude of yeast supplementation effects on ruminal parameters, total tract nutrient digestibility, growth and feed conversion across different studies with sheep. Different methodologies and small numbers of studies necessitated the use of the classical effect size method, in which a unitless standardised effect size (Hedges's g) was used to calculate differences obtained in outcomes between supplemented and non-supplemented sheep. Summary statistics across studies were calculated with fixed and random effects models, whereas subgroup-analysis and meta-regression were applied to identify possible interfering factors that could be responsible for between-study variability. Possible publication bias was evaluated with graphical and statistical tests. Effect sizes for ruminal ammonia nitrogen (33 comparisons), pH (42 comparisons) and total volatile fatty acids (38 comparison) did not (P> 0.10) present heterogeneity among studies, and was not affected by yeast supplementation. No effects (P> 0.05) were detected on the stoichiometry of volatile fatty acids or protozoa counts. Effects sizes calculated for digestibility of dry matter, organic matter, crude protein, acid-detergent fibre and neutral-detergent fibre, which included from 17 to 28 comparisons, showed considerable (>50%) between-study variability. This variability could not effectively be explained by the categorical variables (1) mode of yeast application, (2) feed intake (ad lib versus restricted) or (3) faeces collection method, or the continuous independent variables (1) adaptation period, (2) study period, (3) dietary roughage concentration and (4) dietary crude protein concentration. According to random effects models, digestibility of dry matter, organic matter and crude protein were increased by yeast supplementation, with no effects found for digestibility of fibre components. Substantial unexplained between-study variability (50-90%) was found for growth (13 comparisons) and feed intake (9 comparisons). This meta-analysis presented evidence that addition of dry active S. cerevisiae yeast to diets did not have any effect on growth, feed conversion, ruminal parameters or fibre digestibility in sheep. © 2011 Elsevier B.V.


Sales J.,Institute of Animal Science
Animal Feed Science and Technology | Year: 2012

This review was written to summarise knowledge available on the use of markers to determine total tract apparent digestibility in horses, and to quantify differences in estimates obtained between marker techniques and total collection of faeces. Differences were quantified with a unitless standardised effect size (Hedges's g) and effect sizes within marker, diet (all-forage, forage and concentrate) and nutrients were combined with random effects models to account for unexplained heterogeneity among experiments. Digestibility of all-forage diets estimated by total faecal collection was not different to measurements obtained with acid detergent insoluble ash, 2. N HCl acid insoluble ash, or the n-alkanes C27, C29 and C31. With diets containing forage and concentrate, acid detergent insoluble ash, chromic oxide, indigestible acid detergent fibre, indigestible cellulose or n-alkanes presented similar nutrient digestibility coefficients, and 2. N HCl acid insoluble ash higher dry matter digestibility, compared to total faecal collection. Acid detergent lignin resulted in lower apparent digestibility coefficients with both types of diets. However, combined effect sizes for acid detergent insoluble ash and n-alkanes were based on 2-3 experiments conducted in few (1-2) studies, and should be interpreted accordingly. It is concluded that acid insoluble ash currently presents the most reliable marker that, with certain precautions, could be applied to determine apparent total tract apparent digestibility in horses. © 2012 Elsevier B.V.


Barash I.,Institute of Animal Science
Carcinogenesis | Year: 2012

Nuclear localization of signal transducer and activator of transcription (Stat) 5 marks good prognosis in estrogen receptor/progesterone receptor-positive breast tumors. This positive characteristic is counteracted by studies in laboratory animals demonstrating that deregulated Stat5 activity may convert proper mammary development into a latent oncogenic process. Tumorigenesis is initiated during the parity cycles, most probably during pregnancy, when the activated Stat5 antagonizes or manipulates parity's protective mechanisms. For example, it can alter the differentiation/proliferation balance, induce growth hormone signaling, cause specific alteration in chromatin structure, inhibit tumor-suppressor activity and induce DNA damage that counteracts the enhanced DNA-damage response exerted by parity. Palpable tumors develop after a latent period from individual cells. This happens in the estropausal period in transgenic mice maintaining deregulated Stat5 activity in the mammary gland, or during involution, months after transplantation of transfected cells with constitutively active Stat5. Candidate vulnerable cells are those which maintain high nuclear Stat5 activity. Due to the hazardous outcome of deregulated Stat5 activity in these cells, such as induced DNA damage or high cyclin D1 activity, the gland is prone to transformation. The developing tumors are mostly adenocarcinomas or their subtypes. They are estrogen receptor-positive and maintain a specific Stat5 gene signature that allows tracking their inducer. From a clinical point of view, deregulated Stat5 activity represents a genuine risk factor for breast cancer. Monitoring Stat5 activity during vulnerable periods and developing specific tools for its suppression in breast epithelial cells could potentially limit new incidence of the disease. © The Author 2012. Published by Oxford University Press. All rights reserved.


Spinka M.,Institute of Animal Science
Applied Animal Behaviour Science | Year: 2012

Animal emotions are central to the concept of animal welfare. So far, emotions have been investigated in animal welfare science as within-individual phenomena, i.e. coordinating mechanisms that guide the animal to take appropriate action. However, emotions include an important social dimension. The social side of emotions is being intensely investigated in humans, but surprisingly little quantitative data exist for animals. Transfers of emotions among humans, sometimes labelled as different types of empathy, take different forms, varying in their cognitive complexity, in the match between the observed and the induced emotion, and in their time-scale. Sharing of emotions in humans is closely linked to behavioural resonance, i.e. to strong involuntary propensity to automatically synchronize with and imitate behavioural actions of other individuals, and this resonance results in a shift towards positive emotions and closer affiliation. Not all forms of empathy-type interactions may exist in animals, but there is ample evidence that animals often do transfer emotions among themselves, either through inadvertent cues or through specifically evolved signals. One simple and widespread form of emotional transfer among animals is discussed in more detail, namely, the process called emotional contagion that causes animals to shift, upon perceiving animals in an emotional state, their own affective state in the same direction. Because this process can multiply both negative and positive emotions in animal groups, it can be of importance for welfare in domestic and captive animals. Other types of empathy-like phenomena, such as strengthening of affiliative bonds through emotional and behavioural entrainment may also influence welfare of social animals. Paying attention to the social dimension of animal emotions will promote our understanding of animal welfare and may open new ways to affect it positively, but much empirical research into the specific forms of social animal emotionality is needed before these prospects will be turned into practicable knowledge. © 2012 Elsevier B.V.


Gootwine E.,Institute of Animal Science
Tropical Animal Health and Production | Year: 2011

The Local Awassi, a triple-purpose breed for meat, milk, and carpet-wool production, is a low-prolific, hardy breed that is well adapted to the unfavorable conditions of the Middle East, where it is managed under traditionally extensive to semi-extensive conditions. Breeding work with the Awassi has included within-breed selection, crossbreeding, and gene introgression. Those efforts resulted in a variety of Awassi-derived genotypes that successfully occupy semi-intensive as well as intensive production systems. Thus, within-breed selection resulted in development of the "Improved Awassi"-a dairy-type Awassi strain which, under intensive management, produces over 500 l milk/ewe annually; crossbreeding with the East Friesian breed led to the development of the Assaf dairy breed, which exceeds the Improved Awassi in prolificacy and in year-round breeding activity, and introgression of the B allele of the FecB locus into the Awassi and Assaf breeds resulted in the formation of the prolific Afec Awassi and Afec Assaf strains, with prolificacies of 1. 9 and 2. 5 lambs born per ewe lambing, respectively. Advanced molecular genetics tools have enabled a better understanding of how the Awassi breed was formed during domestication and have uncovered differences in its genetic structure compared to other breeds. Implementing large-scale selection schemes that implement emerging new information on the sheep genome, overcoming threats of inbreeding depression, and further breeding for high uterine capacity are the new breeding goals for the Awassi, Assaf, and their derivatives. © 2011 Springer Science+Business Media B.V.


Wolf J.,Institute of Animal Science
Journal of Animal Science | Year: 2010

The objective of the present study was to estimate heritabilities and genetic correlations for semen and litter size traits using full animal model analyses. Litter size data were available from 28,485 Czech Large White and 10,410 Czech Landrace sows farrowing between 1995 and 2008. The number of litter records was 91,922 and 30,937, respectively. Records on semen traits (37,137 ejaculates from 778 Large White boars and 51,341 ejaculates from 841 Landrace boars) were available from 22 AI centers in the Czech Republic from 2000 to 2009. All calculations were carried out separately for each breed. Number of functional sperm was defined as total number of sperm times the fraction of motile sperm times (1 - the fraction of abnormal sperm). Among the semen traits, semen volume showed the greatest heritability (0.20 ± 0.019 in Large White and 0.25 ± 0.018 in Landrace), followed by sperm concentration with a heritability of 0.18 (SE = 0.012 and 0.014) in both breeds. The heritabilities of the remaining 4 traits (motility, percentage of abnormal sperm, total number of sperm, and number of functional sperm) were around 0.10 (SE = 0.016 to 0.031). Large negative genetic correlations were observed between semen volume and sperm concentration and between motility and percentage of abnormal sperm, especially in Large White. Positive and negative correlations among remaining semen traits were mostly of small magnitude. There was a tendency for increasing litter size to be associated with slight decreases in the total number of sperm and in the number of functional sperm, especially in the Large White breed (genetic correlations of - 0.08 to -0.14 and -0.16 to -0.31, respectively, with SE between 0.100 and 0.114). Some of the correlations between semen and litter size traits (especially with the percentage of abnormal sperm) were breed-specific (positive up to 0.63 ± 0.062 for Large White and negative until -0.41 ± 0.106 in Landrace). Furthermore, parity-specific correlations were observed in the Large White breed. © 2010 American Society of Animal Science.

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