No description available.

Thèse de doctorat : Sciences du Vivant. Aspects moléculaires et cellulaires de la Biologie : Strasbourg 1 : 2007. / Titre provenant de l'écran-titre. Bibliogr. 22 p.

The objective was to examine effects of melatonin supplementation during late gestation on uterine artery hemodynamics, offspring growth, and endocrine profiles. Prior to day 170 of gestation, heifers were trained to the Calan feeding system. On day 190 of gestation, heifers (n = 20) were blocked by BW and then randomly assigned to one of two dietary treatments: 1) 20 mg of dietary melatonin per day (MEL) or 2) no melatonin supplementation (CON). Supplementation ceased on day 262 of gestation. A main effect (P < 0.01) of treatment was observed for total uterine artery blood flow with it being increased in MEL vs. CON. An interaction (P = 0.008) was observed in calf body weight increasing at weeks 8 and 9 in MEL vs. CON. Dietary melatonin could be used to potentially increase uterine blood flow and calf body weight.

Introduction Neonatal mortality and morbidity from premature birth are still a major concern despite significant advances in perinatal medicine. Objective of the study The primary aim of the study was to establish the feasibility of accurately identifying a cohort of vvomen at increased risk of preterm birth using a modified risk assessment score and fetal fibronectin testing in order to undertake a pilot randomised placebo-controlled trial of nifedipine as a tocolytic. Methodology A population of pregnant women was screened prospectively between 24 and 34 weeks of gestation using a modified risk assessment system. Women identified as high-risk for preterm birth were then tested with fetal fibronectin. Those testing positive were randomised to either nifedipine or placebo. The study at this point was randomised, placebo-controlled and double-blind. Measures of outcome were compared for babies of trial vvomen with high-risk women who withheld consent. Main outcome measures Delivery before 34 weeks, neonatal death, admission to the Special Care Baby Unit (SCBU), chronic lung disease and major cerebral abnormality on ultrasound scan constituted the main measures of outcome. Results Five hundred and thirty four vvomen were identified as high-risk for preterm birth. One hundred and forty two women agreed to participate in the study. Forty nine women delivered before 37 weeks' gestation. The system was sensitive in predicting preterm birth before 34 weeks of gestation and within one week of testing for fetal fibronectin in symptomatic women. Babies of non-consenting mothers fared better overall than babies of the trial women. Conclusion Risk factor scoring and fetal fibronectin testing are useful screening tools that can predict preterm delivery. This sysytem can be clinically useful in the management of preterm labour or women at increased risk for preterm birth. There was no impact on the neonatal mortality or morbidity.

No description available.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

La production laitière de la truie est très importante pour la croissance des porcelets et dépend du développement de la glande mammaire. Celle-ci se déroule à trois moments au cours de la vie de la truie, dont lors du dernier trimestre de gestation. À ce moment, plusieurs facteurs peuvent influencer la mammogenèse. Parmi les facteurs hormonaux, la prolactine est très importante pour le développement mammaire à cette période. L’hyperprolactinémie, soit une concentration en prolactine circulante supra-physiologique, des jours 90 à 97 de la gestation, permet d’augmenter la production laitière des truies. Toutefois, l’effet de cette augmentation sur la quantité ou la composition du parenchyme n’est pas connu. Le projet de recherche visait donc à étudier l’effet de l’hyperprolactinémie causée par la dompéridone, donnée soit des jours 90 à 97 ou des jours 90 à 110 de gestation, sur le développement mammaire à la fin de la gestation. Les résultats obtenus sont inattendus, puisque l’hyperprolactinémie a plutôt un impact négatif sur le développement mammaire chez les cochettes traitées pendant 20 jours. Les quantités totales d’ADN, d’ARN et de protéines ont diminué indiquant une baisse du nombre et de l’activité des cellules mammaires. Les cochettes traitées à la dompéridone 20 jours ont une concentration en lactose circulant plus élevée au jour 110 de gestation que celles des autres traitements indiquant un début précoce de la lactogenèse. Cela est aussi corroboré par les résultats histologiques montrant davantage de sécrétion riche en protéines, semblable au colostrum, ainsi que la désorganisation de l’épithélium des alvéoles de la glande mammaire. Cela indiquerait que la glande mammaire, sous l’effet d’une hyperprolactinémie de 20 jours, initie prématurément sa lactogenèse. En l’absence de porcelets pour retirer les sécrétions lactées, le processus de l’involution serait alors amorcé prématurément. / Piglet’s growth rely on the milk yield of the sow which depends on mammary development. Mammogenesis occurs at three important periods in the sow, one being the last trimester of gestation. At this time, several factors can influence the process. Among the hormonal factors, prolactin is very important for mammary gland development for this period. Hyperprolactinemia, a supra-physiological circulating prolactin concentration, occuring on days 90 to 97 of pregnancy, increases the milk production of sows, but the effect on the quantity or composition of the parenchyma is unknown. The research project aims at a better understanding of the effect of hyperprolactinemia caused by domperidone, given from days 90 to 97 or from days 90 to 110 gestation, on mammary development at the end of gestation. Unexpectedly, hyperprolactinemia has a negative impact on mammogenesis in gilts treated for 20 days. Total amounts of DNA, RNA and proteins decreased, demonstrating a decrease in the number and activity of mammary cells. Sows treated with domperidone for 20 days had higher circulating lactose concentrations on day 110 of gestation than sows on the other treatments indicating an early onset of lactogenesis. This is also corroborated by histological results showing more protein-rich secretions (colostrum-like) as well as disruption of mammary epithelial cells. This would indicate that the mammary gland, under the effect of a hyperprolactinemia for 20 days, initiates prematurely its lactogenesis. In the absence of piglets to remove milk secretions, the process of involution would then be prematurely initiated.

Previous research has shown that the productivity of sows housed in an Electronic Sow Feeding (ESF) system is affected by the housing management (static vs. dynamic), stage of gestation at mixing and parity. Familiarity has also been shown to affect the behaviour of group-housed sows. Thus, the objective of this experiment was to determine how the previously mentioned social factors affect the behaviour, physiology and productivity of sows housed in an ESF system. Sows were regrouped into either the static and dynamic pens. Within an introduction group, a subgroup of up to 24 focals sows was observed. The focal sows were chosen based on whether they were mixed pre vs. post-implantation (<12 vs. >46 days post-breeding), familiar vs. unfamiliar with group mates and parity (1st vs. 2nd and 3rd vs. 4th +). Aggression at mixing and at the feeder, injury scores, feeder entry order, space usage, salivary cortisol and farrowing productivity was recorded. The data was analyzed using Proc-Mixed and the General Model for SAS. Housing did not have a significant effect on the any of the parameters examined. Young sows had significantly more piglets born alive when housed in a dynamic system, while old sows had more piglets born alive when housed in a static system (p=0.03). Pre-implant sows initiated more aggressive encounters than post-implant sows (p=0.01). Post-implant sows ate later in the feeding cycle (p=0.03), rested on the slats more (p<0.001) and had higher salivary cortisol concentrations (p=0.0008). However, the cortisol concentrations increased throughout gestation for all sows (p<0.001). Familiarity did not have an effect on any of the variables examined except, familiar sows spent more time lying against the wall (p=0.03) and unfamiliar sows spent more time lying in the centre of the solid area of the pen (p=0.02). Old sows were involved in more aggressive encounters (p=0.04), spent more time fighting at mixing (p=0.02) and laid against the wall more (p<0.001). Young sows tended to received more scratches (p=0.07), ate later in the feeding cycle (p<0.001) and spent more time lying on the slats (p<0.001). Intermediate sows had significantly lower salivary cortisol concentrations (p=0.003). There was not a difference between the static and dynamic management systems. Sows should not be mixed until after embryonic implantation because they are more docile. The intermediate sows underwent the least amount of social stress due to their intermediate position within the dominance hierarchy.

Previous research has shown that the productivity of sows housed in an Electronic Sow Feeding (ESF) system is affected by the housing management (static vs. dynamic), stage of gestation at mixing and parity. Familiarity has also been shown to affect the behaviour of group-housed sows. Thus, the objective of this experiment was to determine how the previously mentioned social factors affect the behaviour, physiology and productivity of sows housed in an ESF system. Sows were regrouped into either the static and dynamic pens. Within an introduction group, a subgroup of up to 24 focals sows was observed. The focal sows were chosen based on whether they were mixed pre vs. post-implantation (<12 vs. >46 days post-breeding), familiar vs. unfamiliar with group mates and parity (1st vs. 2nd and 3rd vs. 4th +). Aggression at mixing and at the feeder, injury scores, feeder entry order, space usage, salivary cortisol and farrowing productivity was recorded. The data was analyzed using Proc-Mixed and the General Model for SAS. Housing did not have a significant effect on the any of the parameters examined. Young sows had significantly more piglets born alive when housed in a dynamic system, while old sows had more piglets born alive when housed in a static system (p=0.03). Pre-implant sows initiated more aggressive encounters than post-implant sows (p=0.01). Post-implant sows ate later in the feeding cycle (p=0.03), rested on the slats more (p<0.001) and had higher salivary cortisol concentrations (p=0.0008). However, the cortisol concentrations increased throughout gestation for all sows (p<0.001). Familiarity did not have an effect on any of the variables examined except, familiar sows spent more time lying against the wall (p=0.03) and unfamiliar sows spent more time lying in the centre of the solid area of the pen (p=0.02). Old sows were involved in more aggressive encounters (p=0.04), spent more time fighting at mixing (p=0.02) and laid against the wall more (p<0.001). Young sows tended to received more scratches (p=0.07), ate later in the feeding cycle (p<0.001) and spent more time lying on the slats (p<0.001). Intermediate sows had significantly lower salivary cortisol concentrations (p=0.003). There was not a difference between the static and dynamic management systems. Sows should not be mixed until after embryonic implantation because they are more docile. The intermediate sows underwent the least amount of social stress due to their intermediate position within the dominance hierarchy.

Master of Science / Department of Animal Sciences and Industry / Robert D. Goodband / A study was conducted on a commercial sow farm to determine the effects of parity and stage of gestation on growth and feed efficiency of gestating sows. These data were also used to model changes in composition of maternal weight gain and products of conceptus throughout gestation. Feed intake and BW were measured daily from d 5 to 112 of gestation for 712 females. From d 5 to 39 of gestation, ADFI was lowest for parity 3+ sows compared to the other periods of gestation. Parity 2 sows, although provided the same feed allowance, had greater ADFI during the first period than parity 3+ sows. Average daily gain was lowest and G:F was the poorest from d 5 to 39 for each parity group compared with d 40 to 109 of gestation. Parity 1 and 2 sow ADG increased following d 39 of gestation but decreased from d 75 to 109. Parity 3+ sow ADG increased in each subsequent period of gestation. Parity 1 sows had the greatest ADG and G:F in comparison to parity 2 and 3+ sows in each period of gestation. Energy available for maternal growth was estimated after accounting for the energy needed to meet the sow’s maintenance requirement and the energy required for the growth of the conceptus. Following d 39 of gestation, energy available for maternal growth decreased at the expense of maintenance and conceptus requirements in each subsequent period of gestation for each parity group. After accounting for the weight of the conceptus, maternal ADG decreased from d 39 to 74, and increased d 74 to 109 of gestation, regardless of parity. Maternal G:F was greatest for parity 1 sows in most gestation periods. In conclusion, parity and stage of gestation impact sow feed efficiency and maternal growth with parity 1 sows having the greatest weight gain and best feed efficiency.