Optimality theories of ageing predict that the balance between reproductive effort and somatic maintenance determines the rate of ageing. Laboratory studies find that increased reproductive effort shortens lifespan, but through increased short-term mortality rather than ageing. In contrast, high fecundity in early life is associated with accelerated senescence in free-living vertebrates, but th...

Early embryonic mortality can be monitored using various techniques and probably the most accurate one is ultrasonography (USG). Since the widespread implementation of transrectal USG for reproductive research in cattle (Griffin and Ginther, 1992), several studies have reported rates of embryonic mortality during early gestation under field conditions. Vasconcelos et al. (1997) characterized em...

BACKGROUND Ability to resist temperature shock is an important component of fitness of insects and other ectotherms. Increased resistance to temperature shock is known to affect life-history traits. Temperature shock is also known to affect reproductive traits such as mating ability and viability of gametes. Therefore selection for increased temperature shock resistance can affect the evolution...

BACKGROUND Estimation of maternal mortality is difficult in developing countries without complete vital registration. The indirect sisterhood method represents an alternative in places where there is high fertility and mortality rates. The objective of the current study was to estimate maternal mortality indices using the sisterhood method in a rural district in south-west Ethiopia. METHOD We...

Background: Maternal mortality estimation is difficult in developing countries that have no complete vital registration. The indirect sisterhood method represents an alternative in places where there is high fertility and high mortality. The objective of our study was to estimate maternal mortality indices by the sisterhood method in a rural district in southwest Ethiopia. Method: We interviewe...

YK, GDD, VLK:Department of Clinical and Population Sciences, College of Veterinary Medicine, 1988 Fitch Avenue, Room 385, St. Paul, Minnesota, 55108; JEP: Department of Animal Science, University of Minnesota, St. Paul, Minnesota, 55108 Summary: This review examines the influence of lactational feed and nutrient intake on common measures of breeding herd productivity: weaning-to-first-service i...

CONTEXT The age of puberty has fallen over the past 130 years in industrialized, western countries, and this fall is widely referred to as the secular trend for earlier puberty. The current study was undertaken to test two evolutionary theories: (a) the reproductive system maximizes the number of offspring in response to positive environmental cues in terms of energy balance, and (b) early pube...

In this work, we intend to describe the reproductive dynamics of Sterna hirundinacea in an island from South Brazil. We studied the reproductive biology of this species in its natural environment and provide data on their growth, survival, and reproductive success in Ilha dos Cardos, Santa Catarina, South Brazil. Samplings were carried out daily on the island throughout the reproductive seasons...

We used field observations of freely foraging Aphytis aonidiae parasitoids in conjunction with results of laboratory studies of A. aonidiae and other Aphytis species to simulate lifetime patterns of behavior and reproduction. Field observations provided estimates of encounter rates with three classes of hosts, the mortality rate from predation on adult parasitoids, and host-handling times for o...