Sow body condition at weaning and reproduction performance in organic piglet production

The objective was to investigate the variation in backfat at weaning and its relations to reproduction results in organic sow herds in Denmark. The study included eight herds and 573 sows. The average backfat at weaning mean�13 mm; SD�4.2 mm) ranging from 10.5 to 17.3 mm among herds shows that it is possible to avoid poor body condition at weaning even with a lactation length of seven weeks or more. No main effect of backfat at weaning on reproduction performance was found, but the probability of a successful reproduction after weaning tended to decrease with decreasing backfat for first parity sows, whereas the opposite was the case for multiparous sows

Genetic aspects of maternal ability in sows

The purpose of this thesis was to gain knowledge about the genetic background of different aspects of maternal ability in sows. Today’s selection for increased litter size at birth will put higher demands on the sow’s ability to take care of her litter, and may cause problems with increasing piglet mortality and decreasing piglet growth. This motivates inclusion of a measure of maternal ability into the breeding goal. The studied traits are different measures of piglet mortality, piglet birth weight, piglet growth, sow behaviour and sow body condition. Both direct genetic effects and maternal genetic effects influenced traits measured on the piglet. The maternal effect was more important than the direct effect for all traits measured prior to weaning. Piglet birth weight was favourably genetically correlated to survival of live born piglets. However, we found unfavourable genetic correlations between stillbirth and birth weight of the piglet. This indicates that selection for increased birth weight is not a recommendable strategy to improve piglet survival at birth. We also conclude that a breeding programme aiming at improving both pre-weaning survival and pre-weaning growth should include both these traits, as we found indications of unfavourable genetic correlations between them. The sow’s capacity for a high pre-weaning growth rate and a high survival rate in her litters was genetically associated with a greater loss of weight and backfat in the sow during lactation. A large loss of body reserves may increase the risk of reproductive problems. Low heritabilities, ranging from 0.01 to 0.08, were estimated for the sow behaviour traits: sow’s response to a screaming piglet, sow’s response to piglet handling, fear of and aggression towards the stockperson. A strong response to a piglet scream was genetically associated with a lower mortality rate, and a high fear response was genetically associated with a higher mortality rate. In conclusion, it seems possible to improve piglet survival rate through selection. However, selection for piglet birth weight is not a good strategy. Sow behaviour, for example fear of the stockperson, could be a possible selection criterion to improve piglet survival. Some attention needs to be paid to the sow’s body condition during lactation when selecting for improved piglet survival and growth

Caracterización térmica de aleaciones nanoestructuradas Fe50Co50 y Fe65Co35

Las aleaciones magnéticas nanoestructuradas a base de FeCo se destacan entre las aleaciones magnéticas convencionales a base de Fe por presentar óptimas propiedades magnéticas blandas, requeridas en una variedad de aplicaciones tecnológicas, industriales y biomédicas. En este trabajo se presentan los resultados obtenidos de la caracterización térmica por calorimetría diferencial de barrido y termogravimetría magnética de polvos puros de Fe y Co, y de polvos magnéticos nanoestructurados a base de Fe50Co50 y Fe65Co35 preparados por el método de Aleado Mecánico de elevada energía. Por medio de estas técnicas y bajo la influencia de diferentes atmósferas inertes como Helio (He),Nitrógeno (N2) y Argón (Ar), se evidenciaron los eventos térmicos que tienen lugar desde temperatura ambiente hasta 900 °C para muestras molidas a diferentes tiempos (0, 10, 15, 20 y 25 horas), eventos tales como las temperaturas de transición magnética y de orden – desorden características de este tipo de muestras y del proceso de moliendaIron-cobalt based nanostructured magnetic alloys stand out among conventional magnetic Fe-based magnetic alloys because they exhibit the optimum soft magnetic properties required in a variety of technological, industrial and biomedical applications. In this work, the thermal characterization by differential scanning calorimetry was carried out using thermogravimetric analysis and magnetic thermogravimetry of Fe and Co pure powders, and nanostructured magnetic powders based on Fe50Co50 and Fe65Co35 prepared with the high energy mechanical alloying method. By means of these techniques and with the influence of different atmospheres as Helium (He), Nitrogen (N2) and Argon (Ar), thermal events for samples milled at different times (0, 10, 15, 20 and 25 hours) were evidenced taking place from -70 °C to 500 °C by differential scanning calorimetry and ambient temperature up to 900 °C in the thermogravimetric analyzer. The observed events, as the temperature in the material varies, are associated with the magnetic transition temperatures, order -disorder phase transitions and stress relaxation effect which are features of this type of samples and the milling proces