Problems of mini-pig breeding

This article provides an overview of some problems of the breeding and reproduction of laboratory minipigs. The most obvious of these are the lack of centralized accounting of breeding groups, uniform selection standards for reproduction and evaluation of breeding animals, as well as minimizing the accumulation of fitness-reducing mutations and maintaining genetic diversity. According to the latest estimates, there are at least 30 breeding groups of mini-pigs systematically used as laboratory animals in the world. Among them, there are both breed formations represented by several colonies, and breeding groups consisting of a single herd. It was shown that the main selection strategy is selection for the live weight of adults of 50–80 kg and the adaptation of animals to a specific type of biomedical experiments. For its implementation in the breeding of foreign mini-pigs, selection by live weight is practiced at 140- and 154-day-old age. It was indicated that different herds of mini-pigs have their own breeding methods to counteract inbred depression and maintain genetic diversity. Examples are the maximization of coat color phenotypes, the cyclical system of matching parent pairs, and the structuring of herds into subpopulations. In addition, in the breeding of foreign mini-pigs, molecular genetic methods are used to monitor heterozygosity. Every effort is made to keep the number of inbred crosses in the breeding of laboratory mini-pigs to a minimum, which is not always possible due to their small number. It is estimated that to avoid close inbreeding, the number of breeding groups should be at least 28 individuals, including boars of at least 4 genealogical lines and at least 4 families of sows. The accumulation of genetic cargo in herds of mini-pigs takes place, but the harmful effect is rather the result of erroneous decisions of breeders. Despite the fact that when breeding a number of mini-pigs, the goal was to complete the herds with exclusively white animals, in most breeding groups there is a polymorphism in the phenotype of the coat color.

Testing a Local Inbreeding Hypothesis as a Cause of Observed Antler Characteristics in Managed Populations of White-Tailed Deer

The increased use of antler restrictions by state game agencies has led to a focus on antlers by the hunting public, particularly the potential for an association between genetics and antler characteristics. We analyzed microsatellite data from 1231 male white-tailed deer (Odocoileus virginianus) from three states (Oklahoma, Mississippi, and Texas) within USA to determine if genetic relatedness, internal relatedness (IR), homozygosity weighted by locus (HL), or correlations among uniting gametes (Fis) influenced total antler points, antler score, non-typical points or antler malformations. Within each location, deer in the lower and upper quartile intervals for number of antler points and score were unrelated (95% CI included 0 or was <0) and relatively heterozygous for four measures of inbreeding. Antler score and points were positively influenced by age but negatively influenced by IR and HL, except for antler score in Mississippi. Relatedness, HL, IR and Fis did not differ between groups of deer with and without antler malformations. Perceived differences in antler quality do not appear to be affected by heterozygosity or a result of close inbreeding because we found deer were unrelated and measures of inbreeding and genome-wide heterozygosity were not correlated with antler characteristics.

The use of inbreeding when breeding dogs of Giant schnauzer breed

Inbreeding is a breeding method that is widely used in dog breeding. However, excessive thoughtless use of this method can have a detrimental effect on the health and reproduction of dogs, which under modern environments can occur due to a lack of professional knowledge among people engaged in breeding, lack of publicly available information about the health of sires and their off spring, and widespread breeding use of popular sires. The purpose of the research was to analyze the use of inbreeding in the breeding of dogs of Giant schnauzer breed of exhibition and working directions and its influence on the multiple pregnancy of dogs. The paper analyzes the use of inbreeding in Giant schnauzer breed in two populations that do not intersect due to the direction of use. There was a significant difference between the average indicators of the inbreeding coefficient in the studied groups; in the exhibition direction close inbreeding and incest are more often used during breeding, while in the working direction moderate inbreeding is mainly used, and incest is not used at all. The male dogs and female dogs in the group of the exhibition direction also have a higher indicator of the inbreeding coefficient. Outbred sires in both groups, in group exhibition such companies, outbreeding is less common than in the group working direction. There was no signifi cant difference between the indicators of multiple pregnancy in the groups. On average, female dogs in the working direction group are used more often than female dogs in the exhibition direction group. The frequency of use of male dogs does not differ significantly.

SELECTION EFFICIENCY OF INBRED CATTLE OF UKRAINIAN WHITEHEAD BREED

The stated results of using outbreeding and inbreeding in a selection of cattle of the Ukrainian Whitehead breed, which belongs to the local population and is preserved only in one breeding herd. It was revealed that animals obtained from related breeding are characterized by a sufficiently high level of productivity and normal reproductive qualities. Although outbred and inbred heifers in the process of growth from birth to 18 months of age differed somewhat from each other in live weight, the difference was not statistically significant. In different periods of growth, both outbred and inbred animals had an advantage, indicating the possibility of improving the trait by purebred breeding methods. The absolute increase in live weight of experimental heifers on rearing was: Group I – 295 kg, II – 289 kg, III – 298 kg, IV – 308 kg and V – 293 kg without a statistically significant difference between the groups, which made it possible to conclude that there was no inbred depression when breeding cattle of a given herd through a related selection of parental pairs. It is recognized that the selection of calves to increase their live weight at birth will not have a positive effect on the trait during the growth of animals, as evidenced by the correlation between them. As a result of the study of reproductive ability, the expediency of obtaining and using inbred cattle in a herd, which was inseminated almost a month earlier than outbred, was proved. Between outbred and inbred cows, a significant differentiation of milk yield for the first – third lactation was found, without a significant advantage of animals obtained by one or another method of purebred breeding. According to the first lactation, the highest milk yield was observed in cows of the close inbreeding group (group V) – 4501 kg, which exceeded the outbred ones by 150 kg and the lower inbred ones (groups II-IV) by 191 – 633 kg. Inbred cattle with distant, moderate and close degrees of inbreeding at the second lactation had from 4629 kg to 4719 kg of milk, with the highest rate in cows of a moderate degree of inbreeding, while outbred cows produced only 4582 kg. Cows of a moderate degree of inbreeding had the highest milk yield in the third lactation – 5204 kg and the lowest – 3897 kg of the group of a close degree of inbreeding. Outbred cows for this trait were superior only to individuals of the group of close inbreeding. The results of a comparative analysis of economically useful traits of outbred and inbred cows and heifers of the Ukrainian Whitehead breed indicate the possibility of using a related selection of parental pairs in a herd to increase the efficiency of interbreeding selection, replicate the hereditary traits of the ancestor and preserve the disappearing domestic breed of cattle.

Puma genomes from North and South America provide insights into the genomic consequences of inbreeding

Pumas are the most widely distributed felid in the Western Hemisphere. Increasingly, however, human persecution and habitat loss are isolating puma populations. To explore the genomic consequences of this isolation, we assemble a draft puma genome and a geographically broad panel of resequenced individuals. We estimate that the lineage leading to present-day North American pumas diverged from South American lineages 300–100 thousand years ago. We find signatures of close inbreeding in geographically isolated North American populations, but also that tracts of homozygosity are rarely shared among these populations, suggesting that assisted gene flow would restore local genetic diversity. The genome of a Florida panther descended from translocated Central American individuals has long tracts of homozygosity despite recent outbreeding. This suggests that while translocations may introduce diversity, sustaining diversity in small and isolated populations will require either repeated translocations or restoration of landscape connectivity. Our approach provides a framework for genome-wide analyses that can be applied to the management of similarly small and isolated populations.

Influence of various selection options on economic and useful signs of the red-and-white cattle

It has been established that the spontaneous use of closely related mating in utility herds in most cases does not give the desired results. The use of close and close inbreeding leads to a decrease in milk yield, live weight of cows and prolongs the service period. When breeding record-keeping cows, moderate and distant inbreeding makes it possible to get along with crosses of large, highly productive lines, distinguished by good health and good reproductive abilities of animals. The degree of heritability of breeding traits with homogeneous selection turned out to be higher than with heterogeneous selection. An increase in the degree of heritability with homogeneous selection can be explained by a clearer manifestation of the additive effect of genetic factors.

Sex-biased dispersal and inbreeding avoidance in Hokkaido brown bears

Natal dispersal likely plays an important role in avoiding inbreeding among large carnivores. We tested the hypothesis that male-biased dispersal reduces close inbreeding by limiting the spatial overlap of opposite-sex pairs of close relatives in brown bears (Ursus arctos) in the Shiretoko Peninsula, Hokkaido, Japan. We genotyped 837 individuals collected in 1998–2017 at 21 microsatellite loci and performed parentage analysis. To calculate natal dispersal distance, we considered the site where the mother was identified as the birthplace of her offspring, and the site where the offspring were identified as their dispersed place. As predicted, we found that dispersal distances were significantly greater for males (12.4 km ± 1.0) than for females (7.7 km ± 0.9), and those for males increased from 3 years old, indicating that males begin to disperse around the time sexual maturation begins. Relatedness decreased with distance among pairs of females, and the mean relatedness was significantly higher between pairs of females than between pairs of males or between female–male pairs within 3 km. Closely related female–male pairs rarely (5–6%) resided in close proximity (< 3 km), compared with pairs of closely related females. Our study revealed that the potential for close inbreeding was low in Hokkaido brown bears because males are effective dispersers.

Influence of outbreeding and inbreeding on the productive longevity of dairy cows

The data on the indicators of the duration and effectiveness of life-time use of Holstein, Ukrainian Black and Red-and White dairy cows obtained from unrelated and different degrees of related mating are presented. The sample includes information on zootechnical records of 15 farms of different regions of Ukraine (Ivano-Frankivsk, Lviv, Volyn, Rivne, Ternopil, Vinnytsya, Kyiv, Cherkasy, Chernihiv and Kirovograd). To assess the productive longevity of cows for each cow were examined such indicators as life expectancy, economic use and lactation, life expectancy, life expectancy of fat in milk, life expectancy of milk fat, average yields for one day of life, one day of economic use and one day of lactation, lactation coefficient. It was established that among studied livestock of dairy breeds more cows was obtained by outbreeding (Holstein breed – 62.2, Ukrainian Black-and-White dairy – 75.5 and Ukrainian Red-and-White – 76.9%). Among the inbred animals, more cows were obtained from distant and moderate degrees of family ties. At the same time, inbred animals were characterized by higher rates of productive longevity compared with outbreeds. Among the inbred animal life expectancy, lasting productive use, duration of lactation, lifetime milk yield, lifetime number of milk fat and number of lactations for the life cows of all studied species obtained by close and moderate inbreeding were the best (exception – lifetime yield of Ukrainian Black- and Red-and-White and lifelong amount of milk fat of Red-and-White animals. According to inbreeding rate less than 0.78 and more than 12.5%, there was a significant deterioration in both the duration of productive use of cows and their lifelong yields. Inbred depression was detected only in Holstein breed animals, which were obtained by close inbreeding. This indicates a significant decline in most indicators of their productive longevity. Ukrainian Black and Red-and-White dairy breeds, which were obtained through close inbreeding, the indicators of life expectancy and life expectancy, on the contrary, increased compared with outbred animals.

Chimpanzees breed with genetically dissimilar mates

Inbreeding adversely affects fitness, whereas heterozygosity often augments it. Therefore, mechanisms to avoid inbreeding and increase genetic distance between mates should be advantageous in species where adult relatives reside together. Here we investigate mate choice for genetic dissimilarity in chimpanzees, a species in which many females avoid inbreeding through dispersal, but where promiscuous mating and sexual coercion can limit choice when related adults reside together. We take advantage of incomplete female dispersal in Gombe National Park, Tanzania to compare mate choice for genetic dissimilarity among immigrant and natal females in two communities using pairwise relatedness measures in 135 genotyped chimpanzees. As expected, natal females were more related to adult males in their community than were immigrant females. However, among 62 breeding events, natal females were not more related to the sires of their offspring than immigrant females, despite four instances of close inbreeding. Moreover, females were generally less related to the sires of their offspring than to non-sires. These results demonstrate that chimpanzees may be capable of detecting relatedness and selecting mates on the basis of genetic distance.