Search

Here, we present the first evidence for brain adaptation in pigs tolerant to the human presence, as a behavioral trait favoring domestication. The study was carried out on minipiglets from population bred at the Institute of Cytology and Genetics (Novosibirsk, Russia). We compared the behavior, metabolism of monoaminergic neurotransmitter systems, and functional activity of the hypothalamic-pituitary-adrenal system, as well as neurotrophic markers in the brain of minipigs differing by tolerance to human presence (HT and LT - high and low tolerance). The piglets did not differ in the levels of activity in the open field test. However, the concentration of cortisol plasma was significantly higher in minipigs with a low tolerance to the presence of humans. Moreover, LT minipigs demonstrated a decreased level of serotonin in the hypothalamus and augmented levels of serotonin and its metabolite 5-HIAA in the substantia nigra as compared to HT animals. In addition, LT minipigs showed increased content of dopamine and its metabolite DOPAC in the substantia nigra and decreased dopamine level in the striatum as well as reduced content of noradrenaline in the hippocampus. Increased mRNA levels of two markers of the serotonin system - TPH2 and HTR7 genes - in the raphe nuclei and in the prefrontal cortex, respectively, were associated in minipigs with a low tolerance to human presence. However, the expression of genes regulating a dopaminergic system (COMT, DRD1, and DRD2) in HT and LT animal groups varied depending on brain structure. In addition, a decrease in the expression of genes encoding BDNF (brain-derived neurotrophic factor) and GDNF (glial cell line-derived neurotrophic factor) was revealed in LT minipigs. The results may contribute to our understanding of the initial stage of domestication in pigs., (© 2023 S. Karger AG, Basel.)

Background: The minipig is a promising model in neurobiology and psychopharmacology. However, automated tracking of minipig behavior is still unresolved problem., New Method: The study was carried out on white, agouti and black (or spotted) minipiglets (n=108) bred in the Institute of Cytology and Genetics. New method of automated tracking of minipig behavior is based on Microsoft Kinect 3-D image sensor and the 3-D image reconstruction with EthoStudio software. The algorithms of distance run and time in the center evaluation were adapted for 3-D image data and new algorithm of vertical activity quantification was developed., Results: The 3-D imaging system successfully detects white, black, spotted and agouti pigs in the open field test (OFT). No effect of sex or color on horizontal (distance run), vertical activities and time in the center was shown. Agouti pigs explored the arena more intensive than white or black animals, respectively. The OFT behavioral traits were compared with the fear reaction to experimenter. Time in the center of the OFT was positively correlated with fear reaction rank (ρ=0.21, p<0.05). Black pigs were significantly more fearful compared with white or agouti animals., Comparison With Existing Method: The 3-D imaging system has three advantages over existing automated tracking systems: it avoids perspective distortion, distinguishes animals any color from any background and automatically evaluates vertical activity., Conclusion: The 3-D imaging system can be successfully applied for automated measurement of minipig behavior in neurobiological and psychopharmacological experiments., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Genetic and physiological functional relationships between major reproductive parameters were studied in domestic prolific mammals with special reference to selection-induced changes in fertility and mothering ability in ten generations of pigs of sino-European Tiameslan composite line, which was first bred in France. Based on our hypothesis, balance equations were derived describing highly adaptive functional coadaptations of reproductive traits. Properties of these equations were examined with regard to natural selection. Selection changes of secretory traits of mammary glands were shown to play a leading role in a correlated increase of biological fertility. Genetically controlled regulatory relationships maintained by natural stabilizing selection were established between fertility, sow milk production, perinatal survival, and survival to weaning. Thus, a system of simple complementary equations characterizing an independent integrative reproductive physiological mother-young(s) system was obtained, which had not been previously published. The self-regulated homeostatic mother-young(s) system, studied for the first time ever, ensured homeostatic development of suckling piglets, compensatory regulation, and stabilization at the optimal level of biological (11.6 +/- 0.17 piglets at birth) and actual (10.0 +/- 0.08 piglets at weaning) fertility in the Tiameslan line.

Fear response and domestic behavior of sheep, cattle, horses, and pigs were studied using four different variants of experimental stress conditions. As standard aversive stimulus, the factor of human presence during the feeding time was used under the following conditions: animals were starved for 12-14 or 2 h before the exposure and fed individually or in a group. In the animal species studied, these conditions were found to reveal phenotypic and genotypic differences in fear response to humans, which is correlated with feeding behavior by regulatory mechanisms. A comparative qualitative and quantitative study of the discrete variation of the associated passive-defensive responses and feeding behavior (as related to domestic behavior) was conducted with regard to the effect of the breed and individual genotypes and the feeding and zoosocial deprivation. A classification scheme of the individual diversity of this behavior in farm animal species is proposed, in which ontogenetic and evolutionary relationships earlier found in sheep were taken into consideration. It is suggested that the progressive ecological and zootechnical specialization alters adaptive reaction norms of stress response in breeds and leads to the formation of the homologous variation in a set of coadapted traits, i.e., constitutional types of animals genetically marked by their behavior. A conclusion is made that heritable polymorphism of domestic behavior represents a new source of adaptive variation for improving the total fitness, welfare, and productivity of farm animals by breeding.

The reaction of the hypothalamic-pituitary-adrenocortical axis (HPA) to social isolation from the herd was studied in 45 ewes of the Altaian breed at the age of 12, 16, and 27 months. The animals belonged to either "wild" or "domesticated" phenotypes which contrasted in the character of feeding and defensive responses to a human. The basal corticoid level in animals of both behavioral phenotypes was similar. The corticosteroid reaction was absent in animals with the "domesticated" type of behavior, while it was significantly pronounced in animals with a clear-cut behavioral reaction of withdrawal from a human ("wild" phenotype) at different ages. Sheep of the "wild" type of behavior were not uniform in the rate of the age-dependent decrease in withdrawal and stress reactions: these reactions were stable in individuals of "conservative" phenotypes. Thus, the ontogenetic formation of the long-term adaptation of the HPA axis of sheep to isolation depends on genetically determined behavior and factors, which control correlated changes in feeding and defensive reactions in animals of the "wild" phenotype.

The relationship between behavioral polymorphism and the variation for the function of the hypothalamic-pituitary-adrenocortical axis (HPAA) was studied in the meat-and-wool (n = 447) and Altaian fine-fleece (n = 45) sheep breeds under production farm conditions. The behavior studied included negatively associated reactions: feeding reactions and defensive reactions in relation to human. In sheep, the intrapopulation variation for the stress level of corticosteroids depended on the effect of behavior, the type of stimulus, and the interaction between these two factors and correlated with the behavior phenotype (r varied from -0.551 to -0.226). In the stress responses to either 24-h starvation or lamb weaning, hormonal reactions were similar in wild-type sheep that have clearly marked defensive reactions and in the sheep of the domestic phenotype that was contrasted to the wild type. In the stress responses to isolation from the herd, transportation, and competition for food, hormonal reactions were stronger in the wild type than in the domestic phenotype; alternatively, in the stress response to being kept in cages in pairs, hormonal reaction was stronger in the domestic phenotype than in the wild type. In the sheep that were placed in cages, a single playing of tape-recorded anxiety signals caused the motivational or emotional stress that was characterized by an unusually long latent period of the progressive HPAA reaction and its subsequent chronic course (up to 9 days). Animals of contrasted behavioral phenotypes differed in the course of the HPAA reaction. Heritable behavioral polymorphism and interaction between behavior and the type of stimulus are the regulation factors in the expression and variability of stimulus-specific reactions of HPAA. Behavior can serve as the genetic marker for individual features of HPAA functioning in the stress response of sheep.

The motivational nature of domestication-related behavior, as well as its formation and variation at the ontogenetic, population, and breed levels were studied. Food motivation participated in the environmental regulation of sheep defensive reactions to humans: an increase in motivation decreased the strength of defensive behavior, and vice versa. Defensive behavior became weaker with age, with the rate of decrease higher in sheep with high food motivation. Comparison of 11 breeds revealed that the polymorphism of domestication-related behavior was breed-specific. In low-specialized breeds, the "wild" class prevailed (77.0-94.7%); it was characterized by a pronounced defensive behavior. In commercial breeds, the range of variation was broader, with a higher proportion of "domestication" classes. In Ost-Friesian sheep, this proportion was 86.0%. It is suggested that the polymorphism of domestication-related behavior was formed in commercial breeds as a result of natural selection for adaptation to breeding-related stresses and artificial selection for productivity.

Tape-record presentation of anxious bleating activates the hypophysal-adrenal system in sheep adapted to experimental conditions. Stressory reaction of the hypophysal-adrenal system is characterized by an unusually long latency (no less than 3 hours) and long duration. The pattern of the observed reaction depends on experimental conditions: in sheep that after stimulation were held in group, activation of the hypophysal-adrenal complex was much shorter than in sheep kept in pairs.

Superovulatory doses of PMSG and hCG, injected to anestrus crossbred ewes, induced more intensive luteinization of large follicles and progesterone secretion in ewes, lambed by twins (9) at first pregnancy, then in the cases of singleton lambed ewes or nonlambing ones (12). The ovaries of 2 ewes, lambed by twins, have healthy follicles, with increased estradiol concentration in their follicular fluid despite the presence of ovulatory follicles, giving corpora lutea. It is concluded that enhanced ovarian reactivity at anestrus can be related to the reserves of the reproductive system in more prolific ewes.