Towards a better understanding of the respective effects of milk yield and body condition dynamics on reproduction in Holstein dairy cows

The overall reproductive performance has decreased over the last decades, involving changes in cyclicity, oestrous behaviour and fertility. High milk yield (MY), low body condition score (BCS) and large body condition (BC) loss have been identified as risk factors. However, these effects are often confounded, as high MY and body lipid reserve mobilization are correlated. The aim of this study was to evaluate the respective effects of MY and BC on post-partum ovarian cyclicity, oestrus and fertility of Holstein cows. This study provides novel information, as MY and BC change were uncoupled in the overall dataset that included 98 lactations and milk progesterone profiles. Cows were assigned to two feeding-level groups: high feed, which achieved high MY and moderate BC loss throughout lactation (8410 kg, −1.17 unit from calving to nadir BCS), and low feed, which limited MY and triggered a large BC loss (5719 kg, −1.54 unit). MY and BC had different effects at different stages of the reproductive process. Cyclicity as well as non-fertilization and early embryo mortality were mainly driven by body lipid reserves, whereas oestrous behaviour and late embryo mortality were related to MY. The results point to possible uncoupling between cyclicity, oestrus and early and late embryo survival allowing compensation along the reproductive process and leading to similar final reproductive performance. In compact calving systems, which require high pregnancy rates within a short period, higher MY strategies appear unsuitable even where BCS is maintained, owing to depressed oestrous behaviour and probably increased late embryo mortality, which delays rebreeding. Similarly, strategies that compromise cyclicity and fertility by excessively low BCS are unsuitabl

Contrasting main selection methods in genetic algorithms

In genetic algorithms selection mechanisms aim to favour reproduction of better individuals imposing a direction on the search process. It does not create new individuals; instead it selects comparatively good individuals from a population and typically does it according to their fitness. The idea is that interacting with other individuals (competition), those with higher fitness have a higher probability to be selected for mating. In that manner, because the fitness of an individual gives a measure of its "goodness", selection introduces the influence of the fitness function to the evolutionary process. Moreover, selection is the only operator of genetic algorithm where the fitness of an individual affects the evolution process. In such a process two important, strongly related, issues exist: selective pressure and population diversity. They are the sides of the same coin: exploitation of information gathered so far versus exploration of the searching space. Selection plays an important role here because strong selective pressure can lead to premature convergence and weak selective pressure can make the search ineffective [14]. Focussing on this equilibrium problem significant research has been done. In this work we introduce the main properties of selection, the usual selection mechanisms and finally show the effect of applying proportional, ranking and tournament selection to a set of well known multimodal testing functions on simple genetic algorithms. These are the most widely used selection mechanisms and each of them has their own features. A description of each method, experiment and statistical analyses of results under different parameter settings are reported.Sistemas InteligentesRed de Universidades con Carreras en Informática (RedUNCI

Improving evolutionary algorithms performance by extending incest prevention

Provision of population diversity is one of the main goals to avoid premature convergence in Evolutionary Algorithms (EAs). In this way the risk of being trapped in local optima is minimised. Eshelman and Shaffer [4] attempted to maintain population diversity by using diverse strategies focusing on mating, recombination and replacement. One of their approaches, called incest prevention, avoided mating of pairs showing similarities based on the parent’s hamming distance. Conventional selection mechanisms does not consider if the members of the new population have common ancestors and consequently due to a finite fixed population size, a loss of genetic diversity can frequently arise. This paper shows an extended approach of incest prevention by maintaining information about ancestors within the chromosome and modifying the selection for reproduction in order to impede mating of individuals belonging to the same “family”, for a predefined number of generations. This novel approach was tested on a set of multimodal functions. Description of experiments and analyses of improved results are also shown.Sistemas InteligentesRed de Universidades con Carreras en Informática (RedUNCI

Efecto de la densidad de alojamiento y la zona del galpón sobre indicadores de bienestar en pollos parrilleros

The aim of this work was to evaluate the effect of decreasing stocking density and shed area on footpad dermatitis, hock burn, and ventral feathers cleanliness of broilers reared in winter. The work was carried out on a commercial farm in the northeast of the Santa Fe province, Argentina. 54,000 broilers were housed in sex-mixed batches, in two darkened sheds, divided into three zones: Panels, Intermediate and Extractors. Two stocking densities were evaluated: 14 and 12 chickens/m2, standard and reduced, respectively. At 41 days feet and hock lesions and cleanliness of ventral feathers was assessed in 120 chickens per area. Significant differences were registered for footpad lesions in Extractors (p = 0.0006), Intermediate (p = 0.0002) and Panels (p <0.0001) zones, with predominance of lesions 1 and 2 in Intermediate and Panels zones with standard density. Non-significant differences were observed for hock lesions in Extractors (p = 0.111) a response not seen in Intermediate (p = 0.024) and Panels (p <0.0001) zones, with more type 2 lesions in both zones under standard density. Feather cleanliness showed significant differences in Extractors (p = 0.014) Intermediate (p = 0.01) and Panels (p <0.0001), with a higher proportion of type 3 plumage dirt with standard density. Welfare indicators behaviour showed the favourable change achieved by reducing stocking density in broilers production.El objetivo de este trabajo fue evaluar el efecto de la disminución de la densidad de alojamiento y de la zona del galpón sobre lesiones en almohadilla plantar, tarso y suciedad de plumas ventrales de pollos de engorde criados en invierno. El trabajo se realizó en una granja comercial en el noreste de la provincia de Santa Fe, Argentina. Se alojaron 54.000 pollos de engorde en lotes mixtos, en dos galpones oscurecidos, divididos en tres zonas: Paneles, Intermedia y Extractores. Se evaluaron dos densidades de alojamiento: 14 y 12 pollos/m2, estándar y reducida, respectivamente. A los 41 días se valoró la presencia de lesiones y suciedad del plumaje ventral en 120 pollos por zona. Las lesiones de almohadilla plantar registraron diferencias significativas en Extractores (p= 0,0006), Intermedia (p= 0,0002) y Paneles (p< 0,0001), con mayoría de lesiones 1 y 2 en Intermedia y Paneles con densidad estándar. Las lesiones de tarso no fueron significativas en Extractores (p= 0,1107), sí en Intermedia (p= 0,0235) y Paneles (p< 0,0001), ambas, con más lesiones tipo 2 en la densidad estándar. En suciedad de plumas hubo diferencias significativas en Extractores (p= 0,014), Intermedia (p= 0,01) y Paneles (p< 0,0001), con mayor proporción de plumaje tipo 3 en la densidad estándar. Las variables evaluadas dan cuenta del cambio favorable en la situación de bienestar alcanzada mediante la reducción de la densidad de alojamiento en pollos de engorde

Contrasting main selection methods in genetic algorithms

In genetic algorithms selection mechanisms aim to favour reproduction of better individuals imposing a direction on the search process. It does not create new individuals; instead it selects comparatively good individuals from a population and typically does it according to their fitness. The idea is that interacting with other individuals (competition), those with higher fitness have a higher probability to be selected for mating. In that manner, because the fitness of an individual gives a measure of its "goodness", selection introduces the influence of the fitness function to the evolutionary process. Moreover, selection is the only operator of genetic algorithm where the fitness of an individual affects the evolution process. In such a process two important, strongly related, issues exist: selective pressure and population diversity. They are the sides of the same coin: exploitation of information gathered so far versus exploration of the searching space. Selection plays an important role here because strong selective pressure can lead to premature convergence and weak selective pressure can make the search ineffective [14]. Focussing on this equilibrium problem significant research has been done. In this work we introduce the main properties of selection, the usual selection mechanisms and finally show the effect of applying proportional, ranking and tournament selection to a set of well known multimodal testing functions on simple genetic algorithms. These are the most widely used selection mechanisms and each of them has their own features. A description of each method, experiment and statistical analyses of results under different parameter settings are reported.Sistemas InteligentesRed de Universidades con Carreras en Informática (RedUNCI

Improving evolutionary algorithms performance by extending incest prevention

Provision of population diversity is one of the main goals to avoid premature convergence in Evolutionary Algorithms (EAs). In this way the risk of being trapped in local optima is minimised. Eshelman and Shaffer [4] attempted to maintain population diversity by using diverse strategies focusing on mating, recombination and replacement. One of their approaches, called incest prevention, avoided mating of pairs showing similarities based on the parent’s hamming distance. Conventional selection mechanisms does not consider if the members of the new population have common ancestors and consequently due to a finite fixed population size, a loss of genetic diversity can frequently arise. This paper shows an extended approach of incest prevention by maintaining information about ancestors within the chromosome and modifying the selection for reproduction in order to impede mating of individuals belonging to the same “family”, for a predefined number of generations. This novel approach was tested on a set of multimodal functions. Description of experiments and analyses of improved results are also shown.Sistemas InteligentesRed de Universidades con Carreras en Informática (RedUNCI

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Women from the Middle East and North Africa in Europe: Understanding their marriage and family dynamics

The aim of this article is to assist the understanding of social workers in Europe of marriage and family dynamics among women from Middle East and North African countries who have moved to Europe. The focus of this article is on husband selection processes and family dynamics after marriage in Egypt, which is used as a case study reflecting culture and norms surrounding marriage in this region. This article reports on the findings of doctoral studies which examined marriage patterns and family dynamics in North Africa and in particular in Egypt where more in-depth data were available. The authors reflect issues surrounding values and process of marriage not only in terms of the implications for practice with social work clients or service users, but also in relation to the potential of women from this region who may join the social care workforce