Birth Mass (birth + mass)

Distribution by Scientific Domains

Selected Abstracts

A review of hand-reared Goeldi's monkey

Since 1977 a breeding group of Goeldi's monkey Callimico goeldii has been maintained at Brookfield Zoo. Between 1977 and 1997 there were 291 births of which 78 infants did not survive. Ninety per cent of the surviving infants have been parent-reared and hand-rearing is only carried out after maternal illness or rejection, or if injuries or other problems affect the infants. At Brookfield Zoo successful hand-rearing of Goeldi's monkey began in about 1979 and has been attempted for 66 (36.30) infants, 20 (10.10) of which survived and 46 (26.20) which did not. Changes to the hand-rearing procedures first outlined in 1982 are described and data are presented on birth mass and patterns of mass gain for successfully hand-reared infants. The circumstances relating to infants that did not survive hand-rearing are also documented. [source]

The sensitive hare: sublethal effects of predator stress on reproduction in snowshoe hares

Michael J. Sheriff
Summary 1.,Prey responses to high predation risk can be morphological or behavioural and ultimately come at the cost of survival, growth, body condition, or reproduction. These sub-lethal predator effects have been shown to be mediated by physiological stress. We tested the hypothesis that elevated glucocorticoid concentrations directly cause a decline in reproduction in individual free-ranging female snowshoe hares, Lepus americanus. We measured the cortisol concentration from each dam (using a faecal analysis enzyme immunoassay) and her reproductive output (litter size, offspring birth mass, offspring right hind foot (RHF) length) 30 h after birth. 2.,In a natural monitoring study, we monitored hares during the first and second litter from the population peak (2006) to the second year of the decline (2008). We found that faecal cortisol metabolite (FCM) concentration in dams decreased 52% from the first to the second litter. From the first to the second litter, litter size increased 122%, offspring body mass increased 130%, and offspring RHF length increased 112%. Dam FCM concentrations were inversely related to litter size (r2 = 019), to offspring birth mass (r2 = 032), and to offspring RHF length (r2 = 064). 3.,In an experimental manipulation, we assigned wild-caught, pregnant hares to a control and a stressed group and held them in pens. Hares in the stressed group were exposed to a dog 1,2 min every other day before parturition to simulate high predation risk. At parturition, unsuccessful-stressed dams (those that failed to give birth to live young) and stressed dams had 837% and 214%, respectively, higher FCM concentrations than control dams. Of those females that gave birth, litter size was similar between control and stressed dams. However, offspring from stressed dams were 37% lighter and 16% smaller than offspring from control dams. Increasing FCM concentration in dams caused the decline of offspring body mass (r2 = 057) and RHF (r2 = 052). 4.,This is the first study in a free-ranging population of mammals to show that elevated, predator-induced, glucocorticoid concentrations in individual dams caused a decline in their reproductive output measured both by number and quality of offspring. Thus, we provide evidence that any stressor, not just predation, which increases glucocorticoid concentrations will result in a decrease in reproductive output. [source]

Influence of maternal mass and condition on energy transfer in Weddell seals

Summary 1Environmental variation influences food abundance and availability, which is reflected in the reproductive success of top predators. We examined maternal expenditure, offspring mass and condition for Weddell seals in 2 years when individuals exhibited marked differences in these traits. 2For females weighing 355 kg there was a positive relationship between maternal post-partum mass (MPPM) and lactation length, but below this there was no relationship, suggesting that heavier females were able to increase lactation length but lighter females were restricted to a minimum lactation period of 33 days. 3Overall, females were heavier in 2002, but in 2003 shorter females were lighter than similar-sized females in 2002 suggesting that the effects of environmental variability on foraging success and condition are more pronounced in smaller individuals. 4There was no relationship between MPPM and pup birth mass, indicating pre-partum investment did not differ between years. However, there was a positive relationship between MPPM and pup mass gain. Mass and energy transfer efficiency were 102 and 54% higher in 2002 than 2003, which suggests costs associated with a putatively poor-resource year were delayed until lactation. 5Heavier females lost a higher proportion of mass during lactation in both years, so smaller females may not have been able to provide more to their offspring to wean a pup of similar size to larger females. 6MPPM had only a small influence on total body lipid; therefore, regardless of mass, females had the same relative body composition. Females with male pups lost a higher percentage of lipid than those with female pups, but by the end of lactation female pups had 45% higher lipid content than males. 7It appears that for Weddell seals the consequences of environmentally induced variation in food availability are manifested in differences in maternal mass and expenditure during lactation. These differences translate to changes in pup mass and condition at weaning with potential consequences for future survival and recruitment. [source]

Oligozoospermia: recent prognosis and the outcome of 73 pregnancies in oligozoospermic couples

ANDROLOGIA, Issue 3 2006
J. A. Van Zyl
Summary The minimum value for each of the five main semen parameters, below which conception rarely occurred or did not occur at all, was calculated in a group of 1884 couples complaining of primary and secondary infertility: 304 conceptions including first as well as consecutive conceptions, occurred. The parameters evaluated were (minimum value calculated in this study between brackets) volume (1.0 ml), sperm count ml,1 (2.0 million), total sperm count (4.0 million), motility (10%), forward progression (2.0 MacLeod units: scale 1,4) and normal sperm morphology (3%). The pregnancy rate in the group of 308 oligozoospermic men and the minimum value of semen parameters were the cornerstones in determining the prognosis for oligozoospermic patients. A sperm count of >2.0 million ml,1 was considered relatively adequate for eventual conception judged by the 68 of 308 (22.1%) pregnancies that occurred among oligozoospermic men in this study, provided that the other five semen parameters showed values above the minimum value. In cases where the average sperm count was <2 million ml,1, the chances for conception became rare, viz five of 308 (1.6%). The total number of pregnancies in the group classified as oligozoospermic was 73 (23.7%). With these pregnancies there was no increase in the rate of foetal wastage and congenital abnormalities. Abortion occurred in 15.09% and ectopic pregnancy in 0.9% among first and consecutive pregnancies. One infant among the 56% boys and 44% girls was born with congenital abnormalities. Most of these infants had a normal birth mass of >2500 g. [source]