A model of energy allocation to predict adaptive capacities in meat sheep

Publishe

Modelling adaptation strategies to climate change in Mediterranean small ruminant systems

PRIMA AdaptHerd projec

Adaptive capacity of Mediterranean sheep over morphological traits at different physiological status (póster)

Publishe

Review: Genetic selection of high-yielding dairy cattle toward sustainable farming systems in a rapidly changing world.

The massive improvement in food production, as a result of effective genetic selection combined with advancements in farming practices, has been one of the greatest achievements of modern agriculture. For instance, the dairy cattle industry has more than doubled milk production over the past five decades, while the total number of cows has been reduced dramatically. This was achieved mainly through the intensification of production systems, direct genetic selection for milk yield and a limited number of related traits, and the use of modern technologies (e.g., artificial insemination and genomic selection). Despite the great betterment in production efficiency, strong drawbacks have occurred along the way. First, across-breed genetic diversity reduced dramatically, with the worldwide use of few common dairy breeds, as well as a substantial reduction in within-breed genetic diversity. Intensive selection for milk yield has also resulted in unfavorable genetic responses for traits related to fertility, health, longevity, and environmental sensitivity. Moving forward, the dairy industry needs to continue refining the current selection indexes and breeding goals to put greater emphasis on traits related to animal welfare, health, longevity, environmental efficiency (e.g., methane emission and feed efficiency), and overall resilience. This needs to be done through the definition of criteria (traits) that (a) represent well the biological mechanisms underlying the respective phenotypes, (b) are heritable, and (c) can be cost-effectively measured in a large number of animals and as early in life as possible. The long-term sustainability of the dairy cattle industry will also require diversification of production systems, with greater investments in the development of genetic resources that are resilient to perturbations occurring in specific farming systems with lesser control over the environment (e.g., organic, agroecological, and pasture-based, mountain-grazing farming systems). The conservation, genetic improvement, and use of local breeds should be integrated into the modern dairy cattle industry and greater care should be taken to avoid further genetic diversity losses in dairy cattle populations. In this review, we acknowledge the genetic progress achieved in high-yielding dairy cattle, closely related to dairy farm intensification, that reaches its limits. We discuss key points that need to be addressed toward the development of a robust and long-term sustainable dairy industry that maximize animal welfare (fundamental needs of individual animals and positive welfare) and productive efficiency, while also minimizing the environmental footprint, inputs required, and sensitivity to external factors

Trophy hunting mediates sex‐specific associations between early‐life environmental conditions and adult mortality in bighorn sheep

Environmental conditions during early development, from conception to sexual maturity, can have lasting consequences on fitness components. Although adult life span often accounts for much of the variation in fitness in long-lived animals, we know little about how early environment affects adult life span in the wild, and even less about whether these effects differ between the sexes. Using data collected over 45 years from wild bighorn sheep (Ovis canadensis), we investigated the effects of early environment on adult mortality in both sexes, distinguishing between natural and anthropogenic sources of mortality. We used the average body mass of yearlings (at about 15 months of age) as a yearly index of environmental quality. We first examined sex differences in natural mortality responses to early environment by censoring harvested males in the year they were shot. We then investigated sex differences in the effects of early environment on overall mortality (natural and hunting mortality combined). Finally, we used path analysis to separate the direct influence of early environment from indirect influences, mediated by age at first reproduction, adult mass and horn length. As early environmental conditions improved, natural adult mortality decreased in both sexes, although for males the effect was not statistically supported. Sex differences in the effects of early environment on adult mortality were detected only when natural and hunting mortality were pooled. Males that experienced favourable early environment had longer horns as adults and died earlier because of trophy hunting, which does not mimic natural mortality. Females that experienced favourable early environment started to reproduce earlier and early primiparity was associated with reduced mortality, suggesting a silver-spoon effect. Our results show that early conditions affect males and females differently because of trophy hunting. These findings highlight the importance of considering natural and anthropogenic environmental factors across different life stages to understand sex differences in mortality

The cost of growing large: costs of post-weaning growth on body mass senescence in a wild mammal

International audienceIndividual body mass often positively correlates with survival and reproductive success, whereas fitness costs of growing large are rarely detected in vertebrates in the wild. Evidence that adult body mass progressively declines with increasing age is accumulating across mammalian populations. Growing fast to a large body can increase the cellular damage accumulated throughout life, leading body growth in early life to be negatively associated with the rate of body mass senescence. Moreover, the onset of mass senescence may strongly depend on both sex-specific reproductive tactics and environmental conditions. Assessing the timing and the rate of body mass decline with increasing age thus offers an opportunity to look for costs of having grown fast, especially after a poor start during early life, in both sexes and in different environments. Using a unique dataset including 30 years of longitudinal data on age-specific body mass collected in two roe deer Capreolus capreolus populations subjected to contrasted environmental conditions, we looked for potential costs of high post-weaning growth rate in terms of steeper rate of body mass senescence. Our analyses of body mass senescence accounted for the potential variation in the onset of senescence and allowed explicit comparisons of this variable between sexes and populations. Higher growth rates late in the growing period (after weaning) were associated with a steeper rate of body mass senescence, regardless of early mass (gained before weaning), but at different extents depending on sex and environmental conditions. Body mass senescence occurred earlier in males than in females, especially in the population facing limiting resources. In the wild, although heavy individuals generally survive better than small ones, the costs of growing large late in the growing period only became apparent late in life through mass senescence