Breeding robust pigs

The objective of this study was to estimate the genetic parameters for thermoregulation traits and the relationships with performance of Large White lactating sows reared in a tropical humid climate. The thermoregulation traits were rectal temperature (RT), cutaneous temperature (CT) and respiratory rate (RR) during lactation measured in the afternoon (1200 h) and in the morning (0700 h). The production traits were sow's average daily feed intake (ADFI), litter BW gain (LBWg) and sow's proportion of BW change between farrowing and weaning (BWc). Complete data included 931 lactating performance on 329 Large White sows from the INRA experimental unit in Guadeloupe (French West Indies). Random regression models using linear spline functions were used for longitudinal data (RT, CT, RR and daily feed intake). Results showed that when ignoring values at the beginning and the end of lactation, the traits studied can be treated as the same trait throughout days of lactation, with fairly constant heritability and variance. However, largest heritabilities and genetic variances were estimated in mid-lactation. Heritability estimates on average performance during lactation were low to moderate for thermoregulation traits (0.35 ± 0.09 for RT, 0.34 ± 0.12 for CT and 0.39 ± 0.13 for RR). Heritability estimates for production traits were 0.26 ± 0.08 for ADFI, 0.20 ± 0.07 for BWc and 0.31 ± 0.09 for LBWg. Significant genetic correlations between thermoregulation traits and production traits were only obtained for ADFI and RR (0.35 ± 0.12). From this study it can be concluded that thermoregulation traits are heritable, indicating that there are genetic differences in heat stress tolerance in lactating Large White sows.

Section: Resultsmentioning

confidence: 99%

Genetic parameters for thermoregulation and production traits in lactating sows reared in tropical climate

Gourdine

Mandonnet

Giorgi³

et al. 2017

“…The concept of robustness in farm animals was defined by Knap (2005) as 'the ability to combine a high production potential with resilience to stressors, allowing for unproblematic expression of a high production potential in a wide variety of environmental conditions'. Indeed, genetic progress in production traits realized at the nucleus level may become constrained in commercial practice if the resulting animals (end products of the breeding system) are raised in conditions that do not support full expression of their genetic potential.…”

Section: Robustnessmentioning

confidence: 99%

Breeding for robustness: the role of cortisol

Mormède

Foury

Terenina

et al. 2011

Robustness in farm animals was defined by Knap as 'the ability to combine a high production potential with resilience to stressors, allowing for unproblematic expression of a high production potential in a wide variety of environmental conditions'. The importance of robustness-related traits in breeding objectives is progressively increasing towards the production of animals with a high production level in a wide range of climatic conditions and production systems, together with a high level of animal welfare. Current strategies to increase robustness include selection for 'functional traits', such as skeletal and cardiovascular integrity, disease resistance and mortality in various stages. It is also possible to use global evaluation of sensitivity to the environment (e.g. reaction norm analysis or canalization), but these techniques are difficult to implement in practice. The hypothalamic-pituitaryadrenocortical (HPA) axis is the most important stress-responsive neuroendocrine system. Cortisol (or corticosterone) released by the adrenal cortices exerts a large range of effects on metabolism, the immune system, inflammatory processes and brain function, for example. Large individual variations have been described in the HPA axis activity with important physiopathological consequences. In terms of animal production, higher cortisol levels have negative effects on growth rate and feed efficiency and increase the fat/lean ratio of carcasses. On the contrary, cortisol has positive effects on traits related to robustness and adaptation. For instance, newborn survival was shown to be directly related to plasma cortisol levels at birth, resistance to bacteria and parasites are increased in animals selected for a higher HPA axis response to stress, and tolerance to heat stress is better in those animals that are able to mount a strong stress response. Intense selection for lean tissue growth during the last decades has concomitantly reduced cortisol production, which may be responsible for the negative effects of selection on piglet survival. One strategy to improve robustness is to select animals with higher HPA axis activity. Several sources of genetic polymorphism have been described in the HPA axis. Hormone production by the adrenal cortices under stimulation by adrenocorticotropin hormone is a major source of individual differences. Several candidate genes have been identified by genomic studies and are currently under investigation. Bioavailability of hormones as well as receptor and post-receptor mechanisms are also subject to individual variation. Integration of these different sources of genetic variability will allow the development of a model for marker-assisted selection to improve animal robustness without negative side effects on production traits.

“…Today, the breeding of livestock species is moving towards the complementary use of local breeds and high-production genotypes to ensure stable production in a wide range of climates and production systems (Food and Agricultural Organization (FAO), 2006), in an attempt to overcome the worldwide nutritional and ecological challenges of the 21st century (Knap, 2005;Ten Napel et al, 2006). The adaptation of animals to the stress elicited by their physical and social environments is one of the first functions under consideration when the objective is to increase production in diversified breeding systems.…”

Section: Introductionmentioning

confidence: 99%

“…Resource allocation theory states that when too much energy is allocated to production, an animal will be unable to cope successfully with environmental changes and/or novel pressures of selection (Beilharz et al, 1993;Schü tz et al, 2004). More robust animals are those that maintain performance despite environmental changes (Knap, 2005).…”

Section: Introductionmentioning

confidence: 99%

Genetics of behavioural adaptation of livestock to farming conditions

Canario

Mignon-Grasteau²,

Dupont‐Nivet

et al. 2013

Behavioural adaptation of farm animals to environmental changes contributes to high levels of production under a wide range of farming conditions, from highly controlled indoor systems to harsh outdoor systems. The genetic variation in livestock behaviour is considerable. Animals and genotypes with a larger behavioural capacity for adaptation may cope more readily with varying farming conditions than those with a lower capacity for adaptation. This capacity should be exploited when the aim is to use a limited number of species extensively across the world. The genetics of behavioural traits is understood to some extent, but it is seldom accounted for in breeding programmes. This review summarizes the estimates of genetic parameters for behavioural traits in cattle, pigs, poultry and fish. On the basis of the major studies performed in the last two decades, we focus the review on traits of common interest in the four species. These concern the behavioural responses to both acute and chronic stressors in the physical environment (feed, temperature, etc.) and those in the social environment (other group members, progeny, humans). The genetic strategies used to improve the behavioural capacity for adaptation of animals differ between species. There is a greater emphasis on responses to acute environmental stress in fish and birds, and on responses to chronic social stress in mammals.