No abstract

Much research has been carried out and published on dairy replacement management, in order to rear heifers as efficiently as possible, from both a technical and economical point of view. In most cases, the aim is to rear the heifers at the lowest cost possible without any deleterious effects on future performances. However, the importance of dairy heifer husbandry is not sufficiently well recognized and probably mishandled by most farmers. The present review aims to give an actual overview of rearing procedures in dairy heifers and possible ways to achieve optimal goals. For many years, it has been well known that rapid rearing lowers the age of sexual maturity and consequently may be an efficient way to reduce the non-producing period prior to conception. But this may impair mammary development and consequently future milk production, at least during first lactation. In addition, a growth rate that is too low may not only be costly but also result in animals that are too fat at first calving, creating problems such as calving difficulties, dystocia, etc. Genetic considerations must also be factored, i.e. frame, size, body weight, etc. have changed during the last 20 years and there are differences between breeds. As a result, some time-honoured recommendations may not be appropriate. The present paper reviews factors and management practices that may affect rearing and subsequent performance of dairy heifers.

-Stillbirth concerns about 2.5 million piglets each year in France and is expected to worsen in the coming years, due to hyperprolific sows. The present study was performed to determine the risk factors of the presence of stillborn piglets or mummies in the litter using data from three experimental herds. From June 1999 until June 2000, sow, stillborn and mummy characteristics were closely recorded around farrowing. Information was recorded on 455 litters, from 308 sows. After selection, a total of 447 litters, originating from 302 crossbred (Large White × Landrace) sows were used. Two hundred and fifty-five litters had no stillborn. Neither individual piglet body weight nor variability of piglet body weight within litters were found to influence stillbirth. A reduction in the average litter or sow live weights increased the probability of having a stillbirth. When a full litter was born with a human presence, the proportion of litters without a stillborn was higher than in cases of partial supervision (65.7 vs. 4.5 to 45.6%). At the same time, the number of litters with two or more stillborn piglets was lower (11.2 vs. 23.6 to 30.9%). Only 46% of the litters had no stillborn when no supervision was performed. These results indicate that good supervision (more than 75% of births with a human presence) decreased stillbirth in pigs, while individual piglet weight did not alter it. A reduction in litter live weight decreased the risk of having mummies, whereas an increased litter size had the opposite effect. hyperprolifiques dans les troupeaux. L'objectif de cette étude est de déterminer les facteurs de risques liés à la présence de porcelets mort-nés et momifiés dans une portée, à partir d'observations réalisées dans trois stations expérimentales. De juin 1999 à juin 2000, les informations autour de la mise bas concernant les truies, les porcelets mort-nés et momifiées sont enregistrées. Ces informations sont disponibles sur 455 portées, issues de 308 truies. Après sélection, 447 portées provenant de 302 truies croisées (Large White × Landrace) sont utilisées. Au total, 255 portées n'ont pas de porcelets mortnés. Le poids individuel du porcelet et la variabilité du poids individuel intra-portée n'ont pas d'influence sur la mortinatalité. La réduction du poids de la portée ou de la truie augmente la probabilité d'avoir des porcelets mort-nés. Lorsque toutes les naissances se déroulent en présence humaine, la proportion de portée sans mort-né est plus élevée que dans le cas d'une présence partielle (65,7 % contre 4,5 à 45,6 %). Dans ce cas, le nombre de portée avec deux porcelets mort-nés ou plus, est plus faible (11,2 % contre 23,6 à 30,9 %). En absence de surveillance, seulement 46 % des portées n'ont pas de porcelets mort-nés. Ces résultats indiquent également qu'une bonne surveillance des mises bas (plus de 75 % des naissances en présence humaine) permet de diminuer la mortinatalité chez le porc, et que le poids individuel n'a pas d'effet. Une diminution du poids moyen de la portée entraîne une baisse ...

No abstract

No abstract