Calf Mass Research Articles

Environmental variation as a driver of predator‐prey interactions

Animals often face the trade‐off of optimizing foraging while limiting predation. In variable and seasonal environments the availability of resources changes spatially and temporally, forcing animals to adapt their spatial foraging patterns over time and, thus, to modify their exposure to predation. Previous research has mostly dealt with the causes and consequences of animal spatial patterns separately, with studies either examining how changes in the environment influence habitat selection, or determining the effects of habitat use on vulnerability to predation. Here we combine these aspects through an examination of how weather conditions affect predation risk by modifying the spatial behavior of the prey. We used reindeer calves (Rangifer tarandus) in Norway to investigate (1) the environmental causes and (2) the survival consequences of habitat use. We further examined how those relationships varied temporally and according to the body mass of calves. We found that deep snow and ice conditions led reindeer to shift from their usually preferred high‐elevation pastures to lowland forested areas. This increase in forest use was associated with lower calf survival, mostly due to elevated lynx (Lynx lynx) predation rates. Golden eagles (Aquila chrysaetos) and wolverines (Gulo gulo) also preyed on calves but their effect was much smaller and not associated with a specific habitat type. The link between climatic conditions, habitat use, and predation changed over the winter season and depended on the body weights of the calves. The effect of harsh weather conditions on reindeer use of forested habitats was stronger towards the end of the winter, which coincides with more deteriorated body conditions and lower food availability on high‐elevation pastures, and predation probabilities were higher for smaller individuals. Our study demonstrates that environmental variation importantly affects predator‐prey interactions.

Reproductive Rate and Calf Body Mass in a North-Boreal Reindeer Herd: Effects of NAO and Snow Conditions

Population demographics of northern ungulates are influenced by density and weather conditions. For caribou and reindeer (Rangifer tarandus) that dig in the snow for winter food, snow accumulation and duration of the snow layer are suggested to be influential. Indices based on large-scale alterations of atmospheric pressure such as the North Atlantic Oscillation (NAO) are connected to climate change and may predict ecological processes better than does local weather. Some empirical evidence of the effects of climate variation is available for Arctic and alpine populations but practically none for sedentary, boreal reindeer. We examined the effects of population density, winter and spring NAO, snow accumulation, and the timing of snowmelt on reproductive success (here the calf/female ratio) and on mean summer body mass of calves in a north-boreal, free-ranging herd of semi-domesticated reindeer in northeastern Finland. In this herd, day of snowmelt explained variation in the calf/female ratio and in the midsummer body mass of calves, more so than NAO, winter snow depth and population density.

How the timing of weather events influences early development in a large mammal.

Capturing components of the weather that drive environment-animal interactions is a perennial problem in ecology. Identifying biologically significant elements of weather conditions in sensible statistics suitable for analysis of life history variation and population dynamics is central. Meteorological variables such as temperature, precipitation, and wind modulate rates of heat loss in animals, but analysis of their effects on endothermic species is complicated by the fact that their influence on energy balance is not invariably linear, even across the thermoneutral range. Rather, the thermal load imposed by a given set of weather conditions is a function of organisms' metabolic requirement, which, crucially, may vary spontaneously both seasonally and across different life phases. We propose that the endogenous component of variation in metabolic demand introduces a temporal dimension and that, as a consequence, the specific effect of meteorological variables on energy balance and attendant life history parameters is a function of the timing of weather events with respect to the organism's metabolic rhythm(s). To test this, we examined how a spontaneous increase in metabolic demand influenced the effect of weather on early development in a large mammal. Specifically, we examined interaction between the exponential rise in the energy requirements of pregnancy and depth of snow, which restricts dams' access to forage, on the body mass of reindeer calves (Rangifer tarandus) at weaning. As expected, we detected a significant temporal component: the specific negative effect of snow on weaning mass was not constant, but increased across pregnancy. The life history response was therefore better predicted by interaction between the magnitude and the timing of weather events than by their magnitude alone. To our knowledge, this is the first demonstration of the influence of an endogenous metabolic dynamic on the impact of weather on a life history trait in a free-living mammal. Evaluating weather variables with respect to endogenous variation in metabolic demand adds biological realism and is likely to improve understanding of the influence of environmental variation on life history traits in many ecological contexts.

Isolated Gastrocnemius Hydatid Cysts : A Case Report = أكياس عدارية منفردة في عضلات ربلة الساق : تقرير حالة

Introduction: Hydatid cysts generally involve the liver and the lungs. Exclusive involvement of muscle is extremely uncommon, especially calf muscles. We report a case of hydatid cyst in gastrocnemius muscle. Case report: A 38 year old female presented with painless right calf mass of one year. Radiological tests showed a cystic lesion suggestive of hydatid cyst in the calf with no liver or lung involvement .Surgical excision of two gastrocnemius cysts was done and the patient was started on Albendazole. The patient had an uneventful recovery. Final histopathological report confirmed the diagnosis of hydatid cyst. Conclusions: Hydatid cyst should be included in the differential diagnosis of any soft tissue mass, especially in endemic areas.

Regional and seasonal patterns of nutritional condition and reproduction in elk

ABSTRACTDemographic data show many populations of Rocky Mountain (Cervus elaphus nelsoni) and Roosevelt (Cervus elaphus roosevelti) elk have been declining over the last few decades. Recent work suggests that forage quality and associated animal nutritional condition, particularly in late summer and early autumn, influence reproduction and survival in elk. Therefore, we estimated seasonal nutritional condition of 861 female elk in 2,114 capture events from 21 herds in Washington, Oregon, Wyoming, Colorado, and South Dakota from 1998 to 2007. We estimated ingesta‐free body fat and body mass, and determined age, pregnancy status, and lactation status. We obtained estimates for most herds in both late winter–early spring (late Feb–early Apr) and in autumn (Nov–early Dec) to identify changes in nutritional condition of individuals across seasons.Body fat levels of lactating females in autumn were consistently lower than their non‐lactating counterparts, and herd averages of lactating elk ranged from 5.5% to 12.4%. These levels were 30–75% of those documented for captive lactating elk fed high‐quality diets during summer and autumn. Body fat levels were generally lowest in the coastal and inland northwest regions and highest along the west‐slope of the northern Cascades. Adult females in most herds lost an average of 30.7 kg (range: 5–62 kg), or about 13% (range: 2.6–25%) of their autumn mass during winter, indicating nutritional deficiencies. However, we found no significant relationships between spring body fat or change in body fat over winter with winter weather, region, or herd, despite markedly different winter weather among herds and regions. Instead, body fat levels in spring were primarily a function of fat levels the previous autumn. Thinner females in autumn lost less body fat and body mass over winter than did fatter females, a compensatory response, but still ended the season with less body fat than the fatter elk.Body fat levels of lactating females in autumn varied among herds but were unrelated to their body fat levels the previous spring. Within herds, thinner females exhibited a compensatory response during summer and accrued more fat than their fatter counterparts over summer, resulting in similar body fat levels among lactating elk in autumn despite considerable differences in their fat levels the previous spring. Level of body fat achieved by lactating females in autumn varied 2‐fold among herds, undoubtedly because of differences in summer nutrition. Thus, summer nutrition set limits to rates of body fat accrual of lactating females that in turn limited body condition across the annual cycle.Pregnancy rates of 2‐ to 14‐year‐old females ranged from 68% to 100% in coastal populations of Washington, 69% to 98% in Cascade populations of Washington and Oregon, 84% to 94% in inland northwestern populations of Washington and Oregon, and 78% to 93% in Rocky Mountain populations. We found evidence of late breeding, even in herds with comparatively high pregnancy rates. Mean body mass of calves (n = 242) in 3 populations was 75 kg, 81 kg, and 97 kg, representing 55–70% of potential mass for 6‐ to 8‐month‐old calves on high‐quality diets. Mean mass of 11 yearling females caught in autumn was 162 kg, approximately 70% of potential for autumn, and pregnancy rate was 27%. Mean mass of 28 yearlings caught in spring was 163 kg and pregnancy rate was 34%.Our data suggest widespread occurrence of inadequate summer nutrition. Summer ranges of just 3 herds supported relatively high levels of autumn body fat (11–13% body fat) and pregnancy rates (>90%) even among females that successfully raised a calf year after year. Most other summer ranges supported relatively low autumn levels of body fat (5–9% body fat), and reproductive pauses were common (<80% pregnancy rates). Overall, our data failed to support 2 common assumptions: 1) summer and early autumn foraging conditions are typically satisfactory to prevent nutritional limitations to adult fat accretion, pregnancy rates, and calf and yearling growth; and 2) winter nutrition and winter weather are the principal limiting effects on elk productivity. Instead, a strong interaction existed among level of summer nutrition, lactation status, and probability of breeding that was little affected by winter conditions—adequacy of summer nutrition dictated reproductive performance of female elk and growth as well as growth and development of their offspring in the Northwest and Rocky Mountains. Our work signals the need for greater emphasis on summer habitats in land management planning on behalf of elk. © 2013 The Wildlife Society.

Nitrogen allocation to offspring and milk production in a capital breeder

Nitrogen (N) is a limiting nutrient for many herbivores, especially when plant availability and N content are low during the period of maternal investment, which is common for arctic ungulates. We used natural abundance of N isotopes to quantify allocation of maternal nitrogen to neonatal calves and milk in wild migratory caribou (Rangifer tarandus). We contrasted female-calf pairs from two herds in northern Quebec/Labrador, Canada: Rivière-George herd (RG; low population size with heavy calves) and the Rivière-aux-Feuilles herd (RAF; high population size and small calves). We assessed whether females of both herds relied on body protein or dietary N to produce the neonatal calf and milk at calving and weaning. Female caribou of both herds relied mostly on body N for fetal development. RAF females allocated less body N to calves than did RG females (92% vs. 95% of calf N), which was consistent with the production of calves that were 8% smaller in RAF than in RG. Allocation of body N to milk was also high for both herds, similar at calving for RAF and RG females (88% vs. 91% of milk N, respectively), but lower in RAF than RG females (95% vs. 99% of milk N) at weaning, which was consistent with a small but significantly greater reliance on dietary N supplies to support milk production at weaning. Female caribou used body protein stores to ensure a constant supply of N for fetal growth and milk production that minimized the effects of trophic mismatches on reproduction. The combination of migration and capital investment may therefore allow females to produce calves and attenuate the effects of both temporal and spatial mismatches between vegetation green-up and calf growth, which ultimately would reduce trophic feedbacks on population growth. Our data suggest that small changes in maternal allocation of proteins over the long period of gestation produce significant changes in calf mass as females respond to changes in resources that accompany changes in the size and distribution of the population.

Real-time MR Imaging Guidance for Percutaneous Core Biopsy of US- and CT-negative Lesion

Biopsies traditionally are performed under ultrasound (US), computed tomography (CT), or fluoroscopic guidance. In situations in which lesions are difficult to visualize with US or CT guidance, magnetic resonance (MR) imaging often can provide better imaging results. The authors describe a case in which a recurrent calf mass not well visualized under fluoroscopy, CT, or US was identified on MR imaging. In the absence of real-time needle visualization, percutaneous interventions under MR guidance have been limited by prohibitively long imaging times. A novel guidance system providing real-time MR guidance of needle position was used to procure a core biopsy specimen of the lesion.

Maternal allocation in bison: co-occurrence of senescence, cost of reproduction, and individual quality

Parental allocation strategies are of profound interest in life history because they directly impact offspring fitness and therefore are highly valuable for understanding population dynamics and informing management decisions. Yet, numerous questions about reproductive allocation patterns for wild populations of large mammals remain unanswered because of the challenges for measuring allocation in the wild. Using a nine-year longitudinal data set on life-history traits of mother–calf bison pairs, we identified sources of variation in relative maternal allocation (calf mass ratio on mother mass) and assessed the occurrence of reproductive costs associated with differential maternal allocation. We found that heavy mothers provided a lower allocation but still produced heavier calves than light mothers. Older females produced lighter calves and tended to decrease allocation as they aged, supporting the occurrence of reproductive senescence. Mothers that had produced a calf the previous year produced lighter calves and allocated less than mothers that did not lactate the previous year, revealing reproductive costs. However, greater maternal allocation did not reduce the probability of breeding in successive years, and the amount of allocation provided by a mother was positively correlated among the offspring she produced, illustrating individual heterogeneity. Although life-history studies are usually classified as either supporting costs of reproduction or individual quality, our study demonstrates that these contrasting evolutionary forces can shape variation within a single trait. Our work illustrates that many processes can coevolve within a population, emphasizing the need to integrate multiple concepts to better understand the evolution of life-history traits. With regard to management of bison herds, if the goal of culling programs is to select for animals with the best performance, this research suggests that managers should account for the condition and previous reproductive status of mothers when taking culling decisions on juvenile bison.

Maternal allocation in bison: co-occurrence of senescence, cost of reproduction, and individual quality

Parental allocation strategies are of profound interest in life history because they directly impact offspring fitness and therefore are highly valuable for understanding population dynamics and informing management decisions. Yet, numerous questions about reproductive allocation patterns for wild populations of large mammals remain unanswered because of the challenges for measuring allocation in the wild. Using a nine-year longitudinal data set on life-history traits of mother-calf bison pairs, we identified sources of variation in relative maternal allocation (calf mass ratio on mother mass) and assessed the occurrence of reproductive costs associated with differential maternal allocation. We found that heavy mothers provided a lower allocation but still produced heavier calves than light mothers. Older females produced lighter calves and tended to decrease allocation as they aged, supporting the occurrence of reproductive senescence. Mothers that had produced a calf the previous year produced lighter calves and allocated less than mothers that did not lactate the previous year, revealing reproductive costs. However, greater maternal allocation did not reduce the probability of breeding in successive years, and the amount of allocation provided by a mother was positively correlated among the offspring she produced, illustrating individual heterogeneity. Although life-history studies are usually classified as either supporting costs of reproduction or individual quality, our study demonstrates that these contrasting evolutionary forces can shape variation within a single trait. Our work illustrates that many processes can coevolve within a population, emphasizing the need to integrate multiple concepts to better understand the evolution of life-history traits. With regard to management of bison herds, if the goal of culling programs is to select for animals with the best performance, this research suggests that managers should account for the condition and previous reproductive status of mothers when taking culling decisions on juvenile bison.

Variation in the Composition of Milk of Asian Elephants (Elephas maximus) Throughout Lactation

We investigated milk nutrient composition from three Asian elephant cows over the first 3 years of lactation, including two consecutive lactations in one cow. Body mass gain is presented for three calves during the first year. Milk samples (n = 74) were analyzed for dry matter (DM), fat, crude protein (CP), sugar, ash, calcium (Ca), phosphorus (P), and potassium (K); gross energy (GE) was calculated. Concentrations of most nutrients changed over lactation: DM, fat, CP, Ca, P, and GE were positively correlated to calf age; sugar was negatively correlated to calf age. GE doubled between birth (1 kcal/g) and 2 years of age (2 kcal/g). After accounting for calf age, GE, fat, Ca, and P concentrations differed among the cows. Milk composition also differed between two lactations from the same cow. When milk nutrients were expressed on a mg per kcal basis, the pattern changes: CP, Ca, and P remained relatively constant over lactation on a per energy basis. Calf mass quadrupled over the first year of life; mass gain was linear at 0.9 kg/day. Asian elephant milk composition is variable, both across lactations and between cows, complicating efforts to determine representative values for comparative studies and for the formulation of elephant milk formulas. The fact that CP, Ca, and P were all relatively constant when expressed on a per energy basis may be of biological significance. The increase in nutrient density over lactation undoubtedly limits maternal water loss, reducing the volume of milk necessary to support the calf.

Orthopaedic Case of the Month: Ossified Calf Mass in a 32-year-old Woman

Orthopaedic Case of the Month: Ossified Calf Mass in a 32-year-old Woman

Results of the biological test of simmental bulls in central Serbia

Exceptionally important aspect in cattle production, from the aspect of production and economy, is ensuring normal and regular fertility. Every cattle breeder wants to have high-yielding animals which at the same time have good fertility. In proper cattle breeding this means that from each cow during single year one healthy calf is obtained. Use of artificial insemination has enabled that one breeding male is used as sire for several tens of thousands of progeny, however, there is always the risk that sires could be carriers of lethal and semi-lethal genes, which can cause huge losses of calves. In order to bring these undesirable occurrences to a minimum, so called bilogical test is included in the breeding and selection activities, i.e. bulls are tested through their progeny for presence of difficult calving (dystocia) abd calf losses caused by genetic anomalies. In Republic of Serbia, this test is carried out on ehtire Simmental population in an exchange of data produced by primary breeding organizations. Per each tested bull, it is necessary to have data on minimum 50 randomly selected calves. Calves are examined visually 65 days after the birth, at the latest. In the present study, the results of the biological testing of 35 Simmental bulls, sires of total 3572 calves on the territory of Central Serbia, in the period 2008-2009, are used. The effect of sires on parameters of biological test were studied: body mass of calves at birth, calf score and calving score. Also, bulls were ranked based on said parameters, male/female calves ratio and percentage of twins and still-born calves for each bull individually were determined. After the rank of bulls was established, the correlation between the rank and studied fertility traits was determined. Correlations were expressed using the Spearman coefficient. Research results show that the effect of bulls was very high p<0,001 on all three parameters of the biological test, and also that the percentage of still born calves for all bulls was within limits, with the exception of bulls Zahlo (HB 1497) and Woz (HB 1433) where it was above 5.

Effects of predator treatments, individual traits, and environment on moose survival in Alaska

AbstractWe studied moose (Alces alces) survival, physical condition, and abundance in a 3‐predator system in western Interior Alaska, USA, during 2001–2007. Our objective was to quantify the effects of predator treatments on moose population dynamics by investigating changes in survival while evaluating the contribution of potentially confounding covariates. In May 2003 and 2004, we reduced black bear (Ursus americanus) and brown bear (U. arctos) numbers by translocating bears ≥240 km from the study area. Aircraft‐assisted take reduced wolf (Canis lupus) numbers markedly in the study area during 2004–2007. We estimated black bears were reduced by approximately 96% by June 2004 and recovered to within 27% of untreated numbers by May 2007. Brown bears were reduced approximately 50% by June 2004. Late‐winter wolf numbers were reduced by 75% by 2005 and likely remained at these levels through 2007. In addition to predator treatments, moose hunting closures during 2004–2007 reduced harvests of male moose by 60% in the study area. Predator treatments resulted in increased calf survival rates during summer (primarily from reduced black bear predation) and autumn (primarily from reduced wolf predation). Predator treatments had little influence on survival of moose calves during winter; instead, calf survival was influenced by snow depth and possibly temperature. Increased survival of moose calves during summer and autumn combined with relatively constant winter survival in most years led to a corresponding increase in annual survival of calves following predator treatments. Nonpredation mortalities of calves increased following predator treatments; however, this increase provided little compensation to the decrease in predation mortalities resulting from treatments. Thus, predator‐induced calf mortality was primarily additive. Summer survival of moose calves was positively related to calf mass (β > 0.07, SE = 0.073) during treated years and lower (β = −0.82, SE = 0.247) for twins than singletons during all years. Following predator treatments, survival of yearling moose increased 8.7% for females and 21.4% for males during summer and 2.2% for females and 15.6% for males during autumn. Annual survival of adult (≥2 yr old) female moose also increased in treated years and was negatively (β = −0.21, SE = 0.078) related to age. Moose density increased 45%, from 0.38 moose/km2 in 2001 to 0.55 moose/km2 in 2007, which resulted from annual increases in overall survival of moose, not increases in reproductive rates. Indices of nutritional status remained constant throughout our study despite increased moose density. This information can be used by wildlife managers and policymakers to better understand the outcomes of predator treatments in Alaska and similar environments. © 2011 The Wildlife Society.

Development of a simple index, calf mass index, for screening for orthostatic hypotension in community-dwelling elderly

The prevalence of orthostatic hypotension (OH) among the community-dwelling elderly is high, but the head-up tilt testing in the laboratory setting is time-consuming and costly. However, an objective index for screening for OH among older people recruited from community settings has not yet been established. Therefore, this study conducted to identify factors that can reveal OH among the elderly recruited from a community setting. A total of 86 people aged ≥60 years underwent head-up tilt testing with beats-by-beats blood pressure measurements at Center for elderly fitness and disease/disability prevention research at Nagoya University School of Health Sciences. OH was defined a reduction in systolic blood pressure of at least 20mmHg or in diastolic blood pressure of at least 10mmHg within 3min of raising the head. Associations among anthropometric measurements, fitness parameters and OH were analyzed using multiple logistic regression. Calf mass index (CMI) (OR=0.488, 95% CI; 0.32–0.743, P<0.001) and alpha-blockers (=0.078, 95% CI; 0.007–0.883, P<0.05) were related to OH. The area under the ROC curve was 74.4% (95% CI; 62.8–86.0, P<0.001) and the discriminatory CMI value was 21.2. Our findings suggest that the CMI can be used for screening for OH in the community-dwelling elderly. This information can help clinicians and health care providers working with older people to identify those at risk of OH.

Pleomorphic hyalinizing angiectatic tumor: Cytomorphologic features on fine‐needle aspiration

Pleomorphic hyalinizing angiectatic tumor (PHAT) is a rare low-grade neoplasm occurring predominantly in the subcutaneous tissue of the lower extremity, which is characterized histologically by intermixed bland spindle cells and larger pleomorphic cells, ectatic blood vessels with fibrin, and prominent hyalinization. Here we describe the cytologic features of PHAT seen on fine-needle aspiration of a right calf mass in a 46-year-old man. The smears were cellular, composed predominantly of bland spindle cells dispersed singly as well as in tissue fragments and characterized by open chromatin and small nucleoli. A second population of pleomorphic spindle cells with coarse chromatin, prominent nucleoli, and occasional intranuclear pseudoinclusions was also present. Many of the pleomorphic cells surrounded hyalizined vessels. No mitotic figures were identified. The cytologic diagnosis was a "spindle cell lesion, NOS" with the differential diagnosis including benign lesions and low-grade neoplasms, including PHAT and schwannoma.

Influence of Predator Harvest, Biological Factors, and Landscape on Elk Calf Survival in Idaho

ABSTRACT We evaluated survival of elk (Cervus elaphus) calves on 2 contrasting study areas in north‐central Idaho, USA, from 1997 to 2004. Recruitment was modest (&gt;30 calves:100 F [calves of either sex: F elk 1 yr old]) and stable on the South Fork study area and low (&lt;20 calves:100 F) and declining on the Lochsa study area. The primary proximate cause of calf mortality on both study areas was predation by black bears (Ursus americanus) and mountain lions (Puma concolor). We experimentally manipulated populations of black bears and mountain lions on a portion of each study area. Black bear harvest (harvest density/600km2) initially doubled on the Lochsa treatment after manipulating season bag limits. Mountain lion harvest also increased by 60% but varied widely during the manipulation period. Harvest seasons were closed for black bears and mountain lions on the treatment portion of the South Fork study area. Using the Andersen—Gill formulation (A‐G) of the Cox proportional hazards model, we examined effects of landscape structure, predator harvest levels, and biological factors on summer calf survival. We used Akaike's Information Criterion (AICc) and multimodel inference to assess some potentially useful predictive factors relative to calf survival. We generated risk ratios for both the best models and for model‐averaged coefficients. Our models predicted that calf survival was influenced by biological factors, landscape surrounding calf locations, and predator harvest levels. The model that best explained mortality risk to calves on the Lochsa included black bear harvest (harvest density/600 km2), estimated birth mass of calves, and percentage of shrub cover surrounding calf locations. Incorporating a shrub X time interaction allowed us to correct for nonproportionality and detect that effect of shrub cover was only influential during the first 14 days of a calf's life. Model‐averaging indicated that estimated birth mass of calves and black bear harvest were twice as important as the next variables, but age of calves at capture was also influential in calf survival. The model that best explained mortality risk to calves on the South Fork included black bear harvest, age of calves at capture, and gender of calves. Model‐averaging indicated that age at capture and black bear harvest were twice as important as the next variable, forest with 33–66% canopy cover (Canopy 33–66). Risk to calves decreased when calves occupied areas with more of this forest cover type. Model‐averaging also indicated that increased mountain lion harvest lowered calf mortality risk 4% for every 1‐unit increase in lion harvest (harvest density/600 km2) but was lower (&lt;25%) in importance compared to age at capture and black bear harvest. Our results suggest that levels of predator harvest, and presumably predator density, resource limitations expressed through calf birth mass, and habitat structure had substantial effects on calf survival. Our results can be generalized to other areas where managers are dealing with low calf elk recruitment. However, because factors vary spatially, a single management strategy applied in different areas will probably not have the same effect on calf survival.

Age-specific changes in different components of reproductive output in female reindeer: terminal allocation or senescence?

Two different processes can lead to a change in individual reproductive output with age in long-lived iteroparous vertebrates. The senescence hypothesis predicts a decline of performance in old age, whereas the terminal allocation hypothesis predicts an increase. Using long-term (>30 years) individually based data of female reindeer, we first assessed age-specific variation in body mass and different components of reproductive output. Then we investigated the contribution of senescence and terminal allocation (the increase in components of reproductive output) processes for shaping observed patterns. We found that female reindeer body mass increased up to about 11.5 years of age, and decreased afterwards, supporting the senescence hypothesis. Calf birth mass, both in absolute terms or for a given female mass, first increased and then declined with female age, also supporting the senescence hypothesis. The female mass gain (June-September) decreased with increasing age, and female change in mass between 2 consecutive years decreased with female age, all patterns again supporting the senescence hypothesis. However, the autumn calf mass did not change with age. Calf body mass in autumn tended to be positively related to female mass gain, supporting a quality effect. Raising a calf had a marked negative effect on female mass gain, indicating energetic reproductive costs of raising a calf. Calf body mass in autumn did not influence yearly female mass change. Overall, our results provided consistent evidence for general effects of senescence on most components of reproductive output and highlighted that both individual heterogeneity and reproductive costs shape female reindeer reproductive tactics.

Variation in Calf Body Mass in Migratory Caribou: The Role of Habitat, Climate, and Movements

Individual differences in body mass exert a major influence on several life-history traits of mammals. We investigated the factors influencing variation in body mass of calves of migratory caribou (Rangifer tarandus )a t birth (June, 19 years of data) and in autumn (October, 15 years of data) in the Riviere-aux-Feuilles (Feuilles, 1991-2003) herd and the Riviere-George (George, 1978-2003) herd in Quebec and Labrador, Canada. Mass at birth (hereafter, birth mass) did not differ between herds, possibly because part of their winter ranges overlapped. However, Feuilles calves were smaller in autumn than George calves, possibly reflecting differences in summer ranges. The birth mass of calves also varied with year, likely as the outcome of both intrinsic and extrinsic factors. Birth and autumn body mass were influenced positively by habitat quality in June, estimated by the normalized difference vegetation index. The North Atlantic Oscillation of the previous winter was positively correlated with autumn mass of the George calves. Previous winter snowfall was negatively related to the mass of George calves, and daily movement rates in summer were negatively correlated with the mass of calves of both herds in autumn. Birth mass was positively related with productivity in October in the George herd and also with productivity 3 and 4 years later, which corresponds to the beginning of reproduction of females. We suggest that a mechanism of delayed quality effect of the calves could have been involved in the decrease of fall productivity and population size of the George herd.

Age-Specific Changes in Reproductive Effort and Terminal Investment in Female Nile Lechwe

Abstract Reproductive effort should negatively correlate with reproductive value, yielding a pattern of increased effort with age. According to the terminal investment hypothesis, females near the end of their reproductive life span should devote more resources to reproduction than those near the start of their reproductive careers. We tested predictions of the terminal investment hypothesis by evaluating 38 years of reproductive life-history data collected from Nile lechwe (Kobus megaceros), an ungulate species living at San Diego Zoo's Wild Animal Park. The maximum reproductive success of Nile lechwe matched predictions of models of lifetime reproductive effort, with the relative mass of newborn calves providing an accurate indicator of the costs of reproduction. Newborn mass was significantly correlated with maternal age, and neonatal males tended to be heavier than neonatal females. Older dams were more likely to produce sons than daughters, dams that produced sons were more likely to die than were da...

Concentration of cortisol, insulin-like growth factor-I and immunoglobulin G class in blood of neonatal calves of different body mass at birth

The objective of this work was to examine whether concentrations of cortisol, insulin-like growth factor-I (IGF-I) and immunoglobulin G class (IgG), in fact blood parameters which are believed to be of extreme importance in the postnatal survival of calves, are dependant on the body mass of calves at birth. Investigations were performed on 12 newborn calves of the Holstein-Friesian breed, placed into two groups on the grounds of their body mass at birth. The first group (n=6) comprised calves whose body mass was more than 35 kg at birth (41.67?3.08 kg), while the second group (n=6) comprised calves whose body mass at birth was less than 35 kg (32.00?3.58 kg). Blood samples were taken immediately preceding the consuming of colostrum, as well as at 32 hours of neonatal life. Cortisol and IGF-I concentrations were determined in blood serum samples taken immediately before colostrum consumption, while IgG concentration was determined in the samples taken 32 hours after the birth of the calves. The cortisol concentration in calves born with a greater body mass (61.51?32.78 nmol/l) was lower (p=0.052) than in calves born with a smaller body mass (94.89?17.74 nmol/l). A significant negative correlation (r= -0.592; p&lt;0.05) was established between the body mass of calves at birth and the cortisol concentration. The IGF-I concentration determined immediately following birth in calves with a greater boy mass at birth (10.17?1.71 nmol/l) was statistically significantly higher (p&lt;0.05) in comparison with calves born with a smaller body mass (7.04?1.15 nmol/l). There was a significant positive correlation (r = 0.519; p&lt;0.10) between the body mass of calves at birth and the IGF-I concentration. Thirty-two hours following birth, the IgG concentration in blood serum of calves born with a bigger body mass (18.72?1.99 g/l) was significantly higher (p&lt;0.05) than in calves born with a smaller body mass (11.68?4.79 g/l). A significant positive correlation was established between the body mass of calves at birth and the IgG concentration determined at 32 hours of neonatal life (r = 0.620; p&lt;0.05). The obtained results point to the conclusion that calves of body mass over 35 kg at birth are better adapted to the conditions of the outer environment in comparison with calves born with a body mass of less than 35 kg. .