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Replacement gilts and early parity sows constitute a large, and increasing, proportion of modern breeding herds. Breeding herd profitability is therefore increasingly dependant on the efficiency of gilt management strategies as well as litter size at first farrowing; however, incidences of reproductive failures and small first litter sizes are common within cohorts of replacement gilts. Hence, this thesis had two primary aims which were addressed in four experiments; one, to identify whether the puberty stimulation and mating strategies developed for genotypes of 20 to 30 years ago are suitable for today’s heavier yet leaner genotypes; and two, to better understand the influence of pre-pubertal growth rate and metabolic status on reproductive maturation, puberty attainment and potential litter size. In experiment 1, 192 Large White/Landrace crossbred gilts were used to compare the effects on puberty attainment of commencing boar exposure at 161, 182 or 203 days of age, and the effect of first mating gilts at either the pubertal or second oestrus on ovulation rate and early embryo survival. Gilts were artificially inseminated at the allocated oestrus, with the reproductive tracts collected at 22.8 ± 0.4 days after first mating (mean ± S.E.M), and the numbers of corpora lutea and viable embryos recorded. Delaying first boar contact until 182 or 203 days of age significantly (P < 0.01) reduced days-to puberty and increased the proportion of gilts attaining puberty within 10 days of start of boar exposure. Gilt age at mating had no effect on potential litter size; however, there was a tendency for gilts mated at their second oestrus to shed 0.6 more ova, and possess one more embryo at day 20 of pregnancy. Experiment 2 determined the effects of long- (chronic) and short- (acute) term moderate dietary restriction on ovarian development and oocyte developmental competence in 161- and 175- day old, pre-pubertal gilts. Both chronic and acute periods of moderate feed restriction reduced the number of medium follicles present on the ovaries of 161- and 175-day old gilts, as well as the proportion of oocytes reaching Metaphase II in vitro. However, feeding level during the 14 days prior to ovary collection had the greatest effect on follicular growth and oocyte quality. Experiments 3 and 4 investigated the effects of the same dietary treatments on the timing of puberty attainment in response to boar exposure and potential litter size following mating at the pubertal oestrus. Chronic dietary restriction during the pre-pubertal period delayed puberty attainment, but the timing of the pubertal response was unaffected by acute, moderate dietary restriction of previously well-fed gilts during the period immediately prior to, and coincident with, boar exposure. Acute dietary restriction or repletion stimulated an increase or decrease, respectively, in pubertal ovulation rates; however, neither the number of viable embryo present on day 22 of gestation nor embryo survival were affected by the nutritional treatments used in these studies. Overall, these results demonstrate that the timing and synchrony of puberty attainment is significantly improved when gilts first receive boar exposure at 182 days of age (or older). It is, therefore, concluded that sexual maturity, as measured by responsiveness to boar contact, occurs later in modern genotypes. It is also evident that within the age range investigated, delaying first mating until the second oestrus does not significantly increase either ovulation rate or embryo number at day 20 post-mating. Further, the current data provide the first evidence that despite profoundly affecting the size and morphology of the antral follicle pool as well as pubertal ovulation rates, subtle alterations in dietary intake have no affect on the number or proportion of embryos surviving the pre-and peri-implantation period. It is evident the litter size of gilts mated at the pubertal oestrus is not determined by the number of ova shed, with the current data demonstrating that increasing ovulation rates results in increased embryo mortality. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1339082 / Thesis (Ph.D.) - University of Adelaide, School of Agriculture, Food and Wine, 2008

Ce travail de recherche a été mené dans l’équipe MODGEN du département GenPhySE, 1388 UMR de l’INRA. Il avait pour perspectives de modéliser les variabilités de la taille de portée des ovins pour une meilleure évaluation génétique et de proposer des modèles d’analyse adoptés à ce type de caractère.Les objectifs de l’étude étaient d'identifier, et d'analyser les facteurs environnementaux et génétiques des variabilités des tailles de portée des brebis et de proposer une méthode adaptée pour canaliser les caractères discrets qui prenne en compte conjointement des objectifs sur la moyenne et sur la variabilité du caractère. La thèse s’appuyait sur des données issues de la chaîne nationale de contrôle de performances en relation avec des organismes de sélection ovin qui sont particulièrement intéressés par les résultats de ces recherches (CORAM). Choix des races. Nous avons considéré trois races dont les fréquences de la taille de portée sont plus ou moins élevées. La race Romane connue par sa forte prolificité ainsi des effectifs contrôlés importants a permis des analyses précises. Les deux autres races choisies sont la race Suffolk et la race Rouge de l’Ouest qui ont servi à tester les modèles sur des populations comportant de moins en moins de portées multiples. La taille de portée des ovins considérée comme une variable continue. Au cours de l’étude, nous avons identifié et hiérarchisé les facteurs de variation environnementaux du niveau de prolificité et de de sa variance pour trois races ovines (Suffolk, Rouge de l’Ouest et Romane). Si les facteurs de variation environnementaux du niveau de prolificité étaient déjà bien connus, peu de données concernaient les facteurs de variation environnementaux de la variance. Nous avons également estimé les paramètres génétiques du niveau de prolificité et de sa variance, ils sont cohérents entre eux. Les héritabilités estimées sur la moyenne sont faibles, en cohérences entre les trois races et avec des études antérieures. La non homogénéité des corrélations estimées par le modèle à deux étapes peut s’expliquer par la relation structurelle entre la moyenne et la variance sur l’échelle observée qui n'est pas prise en compte dans ce type d'analyse. A l'échelle d'une race, cette relation dépend de l’écart spécifique entre les seuils; elle est différente de la relation moyenne – variance observée pour l’ensemble des races et qui est calculée sur des données brutes. La taille de portée des ovins considérée comme une variable discrète Nous avons montré l’existence d’une variabilité d’origine génétique dans les trois races étudiées et nous avons montré que le modèle à seuils homothétique [HTM] s’ajustait mieux aux données et qu'il permettait de calculer conjointement l’effet génétique sur la moyenne et sur la variance. Nous avons aussi montré les limites de ce modèle et nous avons proposé une solution afin de donner un cadre plus général à son utilisation et l’utiliser dans les évaluations génétiques. Nous avons également identifié un critère de sélection pertinent qui permet de sélectionner les individus de même moyenne ayant des variances différentes. Nous avons proposé le modèle à seuils indépendants [ITM] ou le modèle multi caractères avec contrainte, ce modèle considère que chaque réalisation est un caractère. Nous avons montré la faisabilité de ce modèle sur les trois races. Ceci nous a permis de mettre en évidence les problèmes liés à la convergence du programme utilisé, et nous avons proposé d’implémenter ce modèle en modifiant le programme TM. / This research work was conducted in the MODGEN team of GenPhySE department, 1388 UMR of INRA. The aim of the study was to model the range size variability of sheep for a better genetic evaluation and to propose models of analysis adopted for this type of character. The objectives of the study were to identify, and analyze the environmental and genetic factors of ewe range size variability and to propose a suitable method for channeling discrete traits that takes into account both mean and character variability objectives. The thesis was based on data from the national chain of performance control in relation to sheep breeding organizations that are particularly interested in the results of this research (CORAM). Choice of breeds We have considered three breeds whose litter size frequencies are higher or lower. The Romance breed known for its high prolificity and important controlled numbers allowed precise analyzes. The other two breeds selected are the Suffolk breed and the Western Red breed, which were used to test the models on populations with fewer and fewer litters. Sheep litter size considered a continuous variable During the study, we identified and prioritized the environmental variation factors of the level of prolificacy and its variance for three sheep breeds (Suffolk, Western Red, and Romane). ). While the environmental variation factors of the level of prolificacy were already well known, there was little data on the environmental variance factors of the variance. We have also estimated the genetic parameters of the level of prolificacy and its variance, they are coherent with each other. Heritabilities estimated on the mean are low, consistent between the three races and with previous studies. The non-homogeneity of the correlations estimated by the two-stage model can be explained by the structural relationship between the mean and the variance on the observed scale that is not taken into account in this type of analysis. At the scale of a race, this relation depends on the specific difference between the thresholds; it is different from the mean - variance relationship observed for all breeds and calculated on raw data. Sheep litter size considered a discrete variable We have shown the existence of genetic variability in the three races studied and we have shown that the homothetic threshold model [HTM] fits better with the data and that it allowed to calculate jointly the genetic effect on the mean and on the variance. We have also shown the limitations of this model and have proposed a solution to provide a more general framework for its use and use it in genetic evaluations. We have also identified a relevant selection criterion that makes it possible to select individuals of the same average with different variances. We proposed the model with independent thresholds [ITM] or the multi-character model with constraint, this model considers that each realization is a character. We have shown the feasibility of this model on the three races. This enabled us to highlight the problems related to the convergence of the program used, and we proposed to implement this model by modifying the TM program.

Previous research documented that white-tailed deer body mass and antler size varied across physiographic regions of Mississippi. Deer from regions with greater soil fertility had greater body mass and antler size; however, this information is known only for individuals 6 months of age and older. I monitored birth mass and skeletal size of fawns produced by bred, adult, female white-tailed deer transplanted from the Delta, Thin Loess (Loess), and Lower Coastal Plain (LCP) soil regions to fawn in the Mississippi State University Rusty Dawkins Memorial Deer Unit. I evaluated the effect of soil region of origin, litter size, and fawn gender on mass and size of fawns at birth. Birth mass was not as variable as mass of older animals, but LCP fawns were lighter and shorter than loess and/or delta fawns. Twins were lighter and shorter than singletons. Males were heavier than females. Differences between regional birth dates within the pens and estimated regional birth dates based on a fetal growth curve raises questions about the wide-spread application of this method of estimating deer breeding and fawning dates.

Das Ziel der vorliegenden Studie war die Untersuchung der Effekte einer automatischen ad libitum Beifütterung von Milchaustauscher zusätzlich zur Sauenmilch in der Abferkelbucht auf den Gewichtszuwachs, die Verlustrate und die Notwendigkeit medikamentöser Behandlungen der Saugferkel. Zudem wurde der Einfluss der Ersatzmilch auf die Körperkondition der Sauen analysiert. Desweiteren wurde untersucht, ob ein Einfluss auf medikamentöse Behandlungen der Sauen, die Gesäugegesundheit und das Bakterienspektrum der Sauenmilch gegeben ist. Außerdem sollten Aussagen zum hygienischen Status des Milchtassensystems und der angeschlossenen Rohrleitungen und Behälter getroffen werden.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 5 uppsatser.

The aim of the theses was to evaluate the characteristics of reproduction of sows with focus on birth weight of piglets and losses of piglets. Forty-two litters were studied. The average number of piglets born alive was 12.38. The average percentage of stillborn piglets per one litter was 5.43, the percentage of mortality until the weaning was 27.8. The average birth weight of piglets born alive was 1.29 kg. Most of the piglets (51%) fell into 1.051.5 kg category with an average weight of 1.30 kg. The relationship between number of piglets born alive and their birth weight was r = -0,121. The average weight of stillborn piglets was 1.08 kg. The gestation period of gilts was 0.28 day shorter than the sow gestation period and they gave birth to 4.03 fewer piglets born alive than sows. The gilts showed a higher proportion of piglets' mortality until the weaning (the difference was 3.46%). The sows showed higher average weight of piglets born alive (the difference was 0.19 kg). The sows with longer gestation period (114 days) gave birth to 0.15 piglet born alive more than the sows with shorter gestation period (less than 113 days). The sows with shorter gestation period showed smaller proportion of stillborn piglets from all born piglets, the sows with longer gestation period showed smaller proportion of piglets' mortality until weaning. In deliveries longer than 8 hours 10.37 piglets were averagely born alive, which was 2.52 piglets less than for sows with deliveries shorter than 6 hours, or 2.6 piglets less than for the sows with deliveries from 6 to 8 hours. In deliveries shorter than 6 hours was the highest number of stillborn piglets. The highest mortality of piglets was until 24 hours after a birth (33%), 28% of piglets died the second day, 12% died the third day and 9% the fourth day. The mortality decreased noticeably from the fifth day after the birth.

The aim of this diploma thesis is to evaluate the chosen influences which effects the weight of lambs in the age of 100 days of breed texel. The evalution was done from 2013 to 2016 and the basic data set is consisted of 1149 lambs. The observed effects were sex, litter size, month of birth, year of birth, mother's age, father's line, and mother's father line. There was found a statistically highly significant difference in the monitoring of sex influence in male lambs (34,69 kg). A statistically significant difference was found in singles (35,14 kg) when evaluating the influence of litter size. There was found a statistically significant differences between the lambs born in May (36,78 kg) and February (37,29 kg), according to the influence of the month of birth. There is also the influence of the year of birth, a statistically highly significant difference was found between 2016 and 2015. There wasn't found a statistically significant difference in the influence of the mother's age. The influence of the father's line proved a statistically highly significant differences in the TAXI line (36,81 kg) and TAYLOR (37,76 kg). The evaluating of the influence of the mother's father line didn´t show a statistically significant difference in the TRISK line (48,50 kg). There wasn´t found a statistically significant difference in interaction of mother's father line and litter size.

Reproductive behaviour and aspects of group dynamics in the genus Acomys were studied in the respect to the individuals? physical condition, life history traits and social environment. Three of the presented studies reveal the important effect of social environment on the behaviour of group members to the new-coming male and reproductive behaviour of females (sex ratio of the pups and litter size). The other two studies investigate the costs associated with group living and cooperative breeding in Sinai spiny mice and the factors influencing alloparental behaviour. Results of this Ph.D. thesis reveal several aspects of social and reproductive behaviour of group-living mammals and contribute to the understanding of the formation and maintenance of the societies in general.

The aim of the work was to evaluate the quality of boar ejaculate in terms of sperm morphology and the influence on fertility of sows. The data came from 58 sperm collections from 8 boars of one line. The boars were housed in the semen collection centre under the same conditions and were in age from 11 to 21 months. In the ejaculate analysis, the evaluation of the pathologically changed sperms was performed by determining the frequency of the finding of individual morphological changes. To evaluate the effect of semen on the litter size, data from 123 successful inseminations and subsequent births were processed. The results showed that boars in most cases produced ejaculate with an average volume with a lower sperm concentration. The incidence of morphologically abnormal sperms was normal for almost all boars. The most common sperm abnormalities were immature sperms and defects of sperm flagella. It was confirmed that more piglets were born after using insemination doses made from sperm ejaculate with the higher sperm count. Furthermore, when using ejaculate with a morphologically abnormal sperm count below 15%, more piglets were born than when the sperm count was 1525%. In the case of immature sperms, a negative correlation with the number of born piglets has been proven.