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Good morning, my name is Katarzyna Andraszek, I am a professor.

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I work at the Institute of the University in Siedlce.

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Animal Husbandry and Fisheries at the Faculty of Environmental Sciences.

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The topic of my presentation is the effects of crossbreeding and I would like to dedicate time

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just various types of crossing effects and also different crossings,

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which are used in breeding work.

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Crossbreeding is a mating system that involves combining animals together.

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animals representing two or more dissimilar genetic groups

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Crossbreeding is the opposite of inbreeding, but even here

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In some cases, inbreeding, or mating of relatives and crossbreeding.

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they can intersect with each other, they can complement each other.

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The goals that can be achieved through crossbreeding are very diverse, and it is precisely these

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These form the basis for dividing the association system into a variety of distinct methods.

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Procedures can generally be divided into two main groups by assuming

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as the main criterion of breeding intention.

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First, crossings aimed at using and adapting foreign genes.

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in a herd or some population and the other effect is intentions towards utilization

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phenomena of heterozygosity, known as hybrid vigor.

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This diagram shows crosses in a very synthetic way, so we have

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Crossing for utilizing heterosis effects and here we distinguish crossings

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non-domesticated individuals, including interspecies crossbreeding,

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Alternating and rotational. When crossing zebroid lines, we have a whole series of

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from peak to interbreeding, intraracial towards

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periodic selection and alternating periodic selection and the second group of crosses are these

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Crossing for the purpose of adapting foreign genes, and here we distinguish crossing.

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elevating, displacing, and divisive.

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Crossbreeding can increase production levels in two ways. Crossbreeding provides

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Breeder the ability to combine desired traits from two or more breeds

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This is how a higher overall level of performance in individual features is achieved.

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Among hybrid animals than if it could be achieved within a given

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specific group. It is often referred to as racial complementarity.

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Strengths of one race that complement or cover the weaknesses of the other race.

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Another way in which crossbreeding increases productivity is by increasing the yield.

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level of performance in specific traits as a result of heterosis.

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Increased productivity may result from heterosis exhibited in the offspring of hybrids.

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Breeders have long known that hybrids exhibit a variety of traits, including

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Utility can exceed the value of both parent forms.

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This phenomenon is known as hybrid vigor and was later named by American breeders.

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Genetic Shull heterozygosity thus expressing the combination with a heterozygous state

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genotype as the desired state. Heterozygosity is manifested not only in increased

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at a higher level of most economically important functional traits such as, among others.

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Milk production in cattle, egg-laying capacity in chickens, higher body weight in many species.

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Mainly in terms of overall hybrid vigor compared to

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With the output forms. Hence another name for heterozygosity.

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like vigor of hybrids. Now I would like to discuss crossbreeding methods aimed at

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utilization and adaptation of foreign genes in the population.

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Crossing over is not designed to yield immediate heterozygous results.

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His goal is to achieve a lasting breeding effect in the form of

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Improvement or correction of certain flaws of one race by another race.

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Transformation of a primitive race into another that is at a higher level

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breeding or finally creating a new breed based on existing breeds.

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It should be noted that these actions must always be accompanied by constant care.

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to improve environmental conditions. This is an essential condition for obtaining

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depending on the specific breeding goals.

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Several methods of interspecific crossbreeding can be distinguished.

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The first is selective breeding. It is used in case of,

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when a certain animal species basically meets the demands placed on it

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However, it does have some flaws that should be corrected.

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In such a situation, individuals from a different race can be used for correction.

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having this perfect quality particularly well expressed.

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In the context of breeding, polygamy is commonly chosen for this purpose.

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Males of an aristocratic breed, distinguished by well-defined features,

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which will be ennobled.

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Crossbreeding is usually done once, using the resulting offspring for further pairings.

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offspring of mixed blood, gradually moving away from the improving race.

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Crossbreeding should be accompanied by very strict selection.

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Don't explain and only return translated text.

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whether to improve a specific trait by using genes from a different population.

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Selective breeding doesn't necessarily have to be limited to primitive breeds.

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however, there is most often used for example cattle breeding.

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Danish red cattle.

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Even races at a high level of farming culture are often forced to

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Do not use genes from other races. For example, many Western European

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Crossbreeding of dairy cattle breeds with Shorthorn bloodlines for improvement.

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meat utility.

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A staggered intersection is an intersection used to

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resemblance of one race to another with higher utility value.

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It is possible to effectively improve the breed that has utility at its level.

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it represents a certain value. If we are dealing with a primitive race,

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A one-time blood transfusion won't help much. A more effective approach would be to use

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eliminating unwanted traits from the breed.

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It replaces male breeders with breeders of the displacing race.

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The obtained female hybrids are again crossed with males of the dominant breed.

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And so the cycle repeats for several generations.

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After 6 generations of selective breeding, the herd should have

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98,3 of the blood race is replaced and becomes similar to it.

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Then the breeding is usually continued without further crossbreeding.

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Apply only to the most desired type of user.

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This type of crossing is the fastest and most efficient way.

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transformation of inefficient races. Its success largely

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It depends on the proper choice of displacing race, which must be well

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adapted to local natural-environmental conditions.

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The next crossing in this series is a race-crossing.

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If none of the existing races meet the conditions of a specific region.

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On the other hand, local primitive races do not satisfy with their level of utility.

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Do not attempt to create a new race, which on one hand

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not conforming to economic demands, but will be fine

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adapted to existing environmental conditions.

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The material for crossbreeding should not be limited to just two races.

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[but also dependencies on requirements for the type of use and possibly]

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general biological properties of the future race.

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The participation of different races in creating the new is usually not equal.

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They are used depending on the characteristics we want to inherit from them.

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There can also be no specific provision for creating a new race.

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Every such action is very individual depending on the ultimate goal.

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what we want to achieve and the conditions accompanying this process.

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Breeding works conducted in Poland can be an example of race-crossing.

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Mountain sheep or long-haired sheep.

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The Puławska pig breed and the autosexing chicken breed were also created in this way.

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rasa polbar.

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Sharp selection must accompany in the method of crossbreeding.

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leaving individuals for further breeding with a type most similar to the desired one.

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Often also after the crossing period to quickly establish advantageous

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The properties of animals intended to be the foundation of a new breed must undergo selective breeding.

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Another large group of crosses are aimed at utilizing the phenomenon of heterosis.

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Crossbreeding animals to achieve a heterozygous effect

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In the first generation, crossbreeding was generally referred to as utility crossing.

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The offspring of animals from different breeds typically exhibited

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better expressed functional features compared to both parent input forms.

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Heterozygosity is a transient phenomenon and cannot be maintained due to segregation in the next generation.

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To obtain a heterozygous generation, let's always maintain breeding FX.

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Purebred parental forms.

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The occurrence of heterozygosity is not always certain.

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Sometimes, the offspring exhibit an intermediate phenotype in relation to the most interesting traits that breeders cultivate.

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or even less frequently, but less favorable than parents.

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Many useful crossover methods have been developed in search of the most effective ways to combine solutions.

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The first method is alternate crossing, where hybrids must be continuously obtained from pure parental breeds.

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It is difficult to apply in practice and not always cost-effective because these animals are not used for breeding.

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for the purpose of breeding to renovate the herd.

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Interbreeding involves consistently backcrossing hybrids with one and then the other parent race.

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This method is not limited to the exclusive utilitarian maintenance of hybrids.

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Females are also used for reproduction, which partially eliminates the shortcomings of the previous method.

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The heterozygosity of hybrids resulting from backcrossing changes slightly from generation to generation.

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And never reaches as high a value as the F1 generation resulting directly from crossing two races.

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In theory, the heterozygosity of subsequent generations should be around one third of the heterozygosity of the first generation hybrids.

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The practical results achieved mainly in pig farming roughly confirm these assumptions.

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This method in practice may be slightly less efficient than the direct performance of blends.

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However, the end result is very profitable as it does not require the constant maintenance of two purebred herds.

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For this purpose, you just need to have the right number of males from both parent breeds.

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while the female materials are already selected blends.

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Crossing of inbred lines within and between races.

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Heterozygosity results in the phenomenon of heterosis.

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The symptoms of hybrid vigor were known before the theoretical justification of this phenomenon was found.

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When it was found based on a very large number of observations,

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that heterosis arises as a consequence of the heterozygous state of hybrids,

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Efforts were made to identify the most effective mating methods leading to maximum heterozygosity.

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Inbreeding in breeding genetically homogenizes the lines where it is used.

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and at the same time moves apart lines that are not related to each other.

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Realization of this phenomenon has led to the development of many very modern association methods.

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aiming to achieve heterozygosity, with the common feature of crossing animals from closely related breeding lines.

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Crossing between inbred lines.

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Crossing involves combining individuals from different lines.

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within which the animals intended for crossing come from inbred lines.

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This system has been most widely adopted in chicken farming.

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The results of numerous experiments are known that indicate the high effectiveness of this method.

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Next to the single crossing of two breeds or two lines, double crossing can also be used.

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When the input material consists of four races.

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If we label them as ABCD, initially to obtain heterozygous hybrids FX, we cross animals from the AB and CD line breeds.

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In order to maintain the vigor of hybrids in the next generation, hybrids between A and B as well as C and D can be crossed with each other.

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This way we obtain four-way crosses or we also call them four-line crosses.

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Crossing inbred lines within a breed is a variation of the previous method.

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The difference is that inbred individuals from the same line are crossed with each other due to inbreeding.

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genetically can vary significantly.

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The selection of individual lines for intersection may be preceded by trial associations to find

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most suitable in terms of heterozygosity achieved in the hybrid generation.

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The next crossing is periodic selection for the heterozygous effect.

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Crossing of closely related lines is always a costly procedure, and also always associated with the risk of not achieving the intended goals.

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This is the appearance of heterozygosity to such an extent that it would justify the excess breeding costs of inbred lines.

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Search for new methods of obtaining heterozygous hybrids with lower costs and associated risks.

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A method of periodic selection has been developed.

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She recommends that the initial heterozygous population be crossed experimentally with a highly inbred line.

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Such crossing offspring is subjected to a thorough evaluation by selecting pairings.

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resulting in the highest heterozygosity in the offspring.

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Animals from the heterozygous herd that crossed with zebroid individuals yielded the best results.

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are now being bred within their own herd.

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Selection for heterozygote advantage occurs from generation to generation until the most beneficial results are achieved through inbreeding.

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This line, which due to its role can be called a test herd,

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used for association with a heterozygous herd and for evaluating both female and male material,

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because the hybrids are not used as breeding material in this method,

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They only serve as a test for their parent's evaluated herd.

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The next cross in this series is alternate periodic selection for heterosis effect.

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This is also a modification of the previous method.

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Through association checks, which result is the selection criterion within the stat.

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It also aims to obtain balanced trait statistics for optimal utility in producing heterozygous hybrids.

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In contrast to periodic selection, in this method, not a single inbred test herd is used for crossbreeding validation.

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but two loci are unlinked and therefore highly heterozygous.

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The method is very interesting because of the genetic implications it carries.

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Selection aimed at the usefulness of both traits for producing heterozygous hybrids leads to gradual homogenization within each of them.

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This limitation of variability is mutually directed to beneficially complement the genotype of an individual from the opposite herd.

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If we accept the theory of overdominance as an explanation for the phenomenon of heterozygosity,

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theoretically the best complementarity of genotypes of both parents should be achieved then,

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when all genetic loci expressing dominance are in a homozygous state.

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This method leads to an increase in homozygosity within the herd.

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In cases of inbreeding, the homozygosity of individual genetic loci is randomly determined.

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Under periodic selection, the homozygosity of interacting genes is established.

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is most beneficial when crossing with a specific herd.

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Genetic consequences of crossing over.

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The genetic effects of crossing are the opposite of the genetic effects of inbreeding.

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Hub stress causes depression with a reduced reproduction rate, decreased offspring viability.

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reduced rate of growth with delayed sexual maturation and delayed attainment of physiological maturity.

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Generally, the same characteristics that show the highest depression in a hub node.

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the same traits that show the greatest heterozygosity during crossing.

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There are two basic genetic requirements for a trait to exhibit heterozygosity.

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To avoid genetic diversity between crossed races,

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and there must be certain non-additive genetic effects for a given trait.

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Failure to meet any of these conditions in the case of a specific crossword puzzle,

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would not exhibit heterozygosity.

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In such a case, the expected offspring outcomes of the hybrid would simply be the average performance results.

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Both pureblood parents participating in the crossword.

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In the case of traits expressing heterozygosity, the magnitude of heterozygosity will depend on

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Always from the degree of genetic diversity between two parental races.

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Genetic diversity refers to the degree of similarity or difference in genetic makeup.

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between the two races. Races of similar origin and which during development are expected to

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have been subjected to similar selective pressure, they will be much more genetically similar.

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than races of completely different origins and chosen for different purposes during their development.

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Negative gene effects refer to types of gene actions that exist in reference

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Many pairs of genes are involved in the expression of a specific trait.

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These effects can be divided into two categories. Non-additive gene effects, which are expressed

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In individual gene pairs based on the level of dominance and non-additive gene effects,

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that result from the interaction between gene effects at a specific locus

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The influence of genes on one or more loci is referred to as epistasis.

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Epistatic gene action involves combinations of genes at one locus interacting with effects.

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combinations of genes from other loci. There are many different types of epistatic effects,

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but their relative impact is very difficult to measure due to their complexity.

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It seems unlikely that these epistatic effects are the main cause of heterosis.

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In the case of most herds. The aim of crossbreeding is to achieve certain desired goals.

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These include achieving heterosis and the ability to quickly activate desired traits.

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Genetic material and the chance to combine several desired traits in animal breeding.

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Heterozygosity, or the exuberance of hybrids, is associated with a maximally heterozygous state of the genotype.

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Many different methods have been developed for obtaining heterozygous hybrids. Many of them are based on

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For the initial kinship breeding and then crossing of inbred animals among themselves.

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The possibility of using different crossing methods depends largely on the fertility of the species.

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Complementary combination of crossed varieties or races and additional impact of heterosis

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makes crossing a very important breeding system in commercial production systems.

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Thank you very much for your attention.