FACTORS OF EVALUATION OF BREEDING BULLS AND MANAGEMENT OF BREEDING POPULATIONS

В статье рассмотрены цифровой формат оценки племенной ценности инбредных быков-производителей по качеству потомства и ее влияние на последующие поколения животных. Выявление инбредного гетерозиса у производителей помогает сделать оценку быков по качеству потомства более информативной за счет определения глубины изменения параметров генетической структуры популяции и степени увеличения частоты рецессивных генов в подконтрольных популяциях. Одной из причин значительной разницы в удое, МДЖ и МДБ российских и американских коров голштинской породы являлась их удаленность от родоначальника. Другой причиной считается стремление селекционеров к инбридингу на выдающихся предков, однако в случае инбредного гетерозиса высокие показатели родителей быстро затухают в последующих поколениях потомков. Исследования были проведены в хозяйствах Московской области малой и средней производственной мощности. Для сравнения проанализированы результаты оценки быков-производителей из США и других стран с высокоразвитым молочным скотоводством. Методами изучения были имитационный и регрессионный анализ данных первичного зоотехнического учета и собственных исследований. Эксперимент показал, что быки-производители с высокими степенями родства уменьшали изменчивость признаков молочности среди дочерей: по удою — на 77,9%; по МДЖ — на 33,4%; по МДБ — на 36,0%, по сравнению с отцами, имеющими низкие степени родства. При этом в их поголовье в первом поколении повышается генетический тренд по удою на 14,3—21,4%, а племенная ценность — на 10,8—26,8%. В настоящее время в зарубежных популяциях голштинской породы широко применяют геномный метод оценки племенной ценности, при котором не требуется информация о родословных животных и не учитывается степень их родства, что отрицательно влияет на получение высококачественного потомства. Повышение племенной ценности по признакам в популяции сыновей и внуков быков-лидеров породы угасает, если в генофонде родителей имел место инбредный гетерозис. The article considers of the inbred breeding bulls breeding value by offspring quality and its impact on subsequent generations of animals’ digital format assessing. Identification of inbred heterosis helps to make the bulls’ assessment by the offspring quality more informative, by determining the depth of changes in the genetic structure of the population parameters and the recessive genes at populations frequency degree increase controlling. One of the reasons for the significant difference in milk yield, MJ and MDB of Russian and American Holstein cows was their distance from the ancestor. Another reason is considered to be of the breeders to inbreeding for outstanding ancestors’ desire, but in the case of inbred heterosis, high rates of parents quickly fade in descendants in subsequent generations. The research was carried out in the farms of the Moscow region of small and medium production capacity. For comparison, the results of the evaluation of breeding bulls in the United States and other countries with highly developed dairy cattle breeding were analyzed. The research methods were simulation and regression analysis of primary zootechnical accounting data and authors’ own research. Experimental data showed that breeding bulls with high degrees of relation reduced the variability of milk production among daughters by milk yield in 77.9%: for MJ in 33.4%; for MDB in 36.0% in compared with fathers with relation’s low degrees. At the same time, in livestock’s first generation, the genetic trend in milk yield increases in 14.3—21.4%, and the breeding value in 10.8—26.8%. Currently, the genomic method of assessing the breeding value is widely used in foreign populations of the Holstein breed, which does not require information about the pedigrees of animals, and does not take into account the degree of their kinship, which negatively affects the production of high-quality offspring. The breeding qualities of the sons of the bull leaders of the breed are quickly disabled the surge of increased breeding value by signs in the population of sons and grandchildren of bulls-leaders of the breed is fading if inbred heterosis took place in the parents' gene pool.

Parental control: ecology drives plasticity in parental response to offspring signals

Different bird species have completely different parent-offspring interactions. When food is plentiful, the chicks that are begging the loudest are fed the most. When food is scarce, bird species instead feed the largest offspring. While this variation could be due to parents responding to signalling differently based on food availability, it could equally be due to offspring adjusting their behaviour, or to variation in information availability. We tested between these competing explanations experimentally, by manipulating food availability in a population of wild great tits, Parus major, while standardising offspring behaviour and size. We found that when food was more plentiful, parents were: (1) more likely to preferentially feed the chicks that were begging the most; and (2) less likely to preferentially feed larger chicks. In addition, we consistently found these same patterns, in a meta-analysis across 57 bird species. Overall, our results suggest that parents have more control over food distribution than offspring do, and that they flexibly adjust how they respond to both offspring signals and cues of offspring quality in response to food availability. Consequently, depending upon environmental conditions, predictably different signalling systems are favoured.

EFFICIENCY OF USE OF THE "NEW" AND "OLD" SELECTION ALPHA BULLS’ DESCENDANTS EVALUATED BY GENOME AND OFFSPRING QUALITY

Дана оценка племенной ценности (ПЦ) потомков быков-лидеров голштинской породы «новой» и «старой» селекций США в условиях хозяйств Ленинградской области. В среднем, повышение молочной продуктивности от использования импортной спермы 68 проверенных по качеству потомства быков составило +79 кг молока (10133 кг, 3,82% жира, 3,23% белка). Наиболее высокий показатель ПЦ по удою — у 18 потомков быков-лидеров «новой» селекции: +175 кг при одинаковом содержании жира и белка в молоке (10673 кг, 3,84% жира, 3,25% белка). У потомков быков-лидеров «старой» селекции ПЦ по удою была ниже и составила +53 кг молока (9989 кг, 3,81% жира, 3,22% белка). Выявлена положительная связь (P<0,001) между ПЦ потомков быков-лидеров, оцененных по геному в США и по качеству потомства в хозяйствах Ленинградской области: по удою +0,634; по содержанию жира в молоке — -0,476; по содержанию белка — +0,444. Приведены предварительные данные о сокращении генерационного интервала между поколениями геномно оцененных быков при использовании их в подборах пар в племзаводе. Выявлено, что при использовании геномно оцененных потомков быков-лидеров высокой ПЦ «старой» селекции можно избежать близкородственного разведения и обеспечить генетическое улучшение животных по селекционным признакам. Breeding value (BV) evaluation of the descendants of alpha bulls from the “new” and “old” USA’s selections of the Holstein breed under the conditions of the farms located in the Leningrad Region is presented. In average, the increase of milk yield due to the use of imported sperm of 68 bulls with the verified offspring quality amounted to +79 kg of milk (10133 kg; fat — 3.82%; protein — 3.23%). The highest BV parameter by milk yield was registered in 18 descendants of the “new” selection’s alpha bulls: +175 kg with similar fat and protein content of milk (10673 kg; fat — 3.84%; protein — 3.25%). BV of the descendants of the “old” selection’s alpha bulls by milk yield was lower and amounted to +53 kg of milk (9989 kg; fat — 3.81%; protein — 3.22%). A positive relationship (P<0.001) was identified between BV of the descendants of alpha bulls which were evaluated by genome in the USA and by the quality of offspring in the farms of the Leningrad Region: by milk yield — +0.634; by fat content in milk — -0.476; by protein content in milk — +0.444. Preliminary data concerning the reduction of the generation interval between the generations of genome-assessed bulls upon their use for the selection of pairs in the breeding plant was presented. It was found, that the use of genome-assessed descendants of “old” selection’s alpha bulls with the high BV parameter can be carried out avoiding closely related breeding and ensuring genetical improvement of animals by selection traits.

Reproductive Rates of Merino Ewes and Offspring Quality under AI Program

Reproductive wastage is a major economic burden in sheep production globally, especially within Australia as livestock production systems face increased pressure from climatic variability (e.g. prolonged droughts or flooding). Sheep are sensitive to acute changes in their environment such as heat stress, which if not adequately monitored will result in significant production losses such as reproductive failure, increased parasite and worm burden, morbidity and mortality risks. Through basic and applied research in the areas of stress and reproductive physiology our team has made significant advancements in the understanding of sheep behaviour and physiological responses to acute and chronic stressors. Using minimally invasive hormone monitoring technology in combination with field based assessment of sheep health and productivity traits, our team has delivered new knowledge on how sheep react to acute environmental stress and how it impacts on sheep reproduction. In this chapter, we evaluated the fertility rates and embryo quality of Merino ewes under AI breeding program. We discuss factors such as heat stress that can impact on ewe and offspring quality.

EFFICIENCY OF DIFFERENT ASSESSMENT METHODS OF BREEDING BULLS OF BLACK-AND-WHITE BREED BY THE OFFSPRING QUALITY

The paper presents results of assessing black-and-white bulls by the quality of the offspring with application of different methods. The evaluation of bulls was carried out with application of the “daughter-mother” method in the conditions of Volzhsky Research Institute of Hydraulic Engineering and Land Reclamation. The valuation showed that the bulls Aist 7 and Muscat 8 increased milk yield of daughters, in comparison with mothers, by 951 and 486 kg, or by 26.7 and 12.9%. The rest of the servicing bulls reduced milk yield of the offspring by 46 - 1019 kg (1.1 - 24.7%). When assessing the bulls using the “daughterpeer” method, the highest milk productivity was shown by the descendants of Sazan 25 and Aist 7 of Vis Back Ideal line, which surpassed their peers in milk yield by 273 and 419 kg, or by 3.8 and 5.7%, respectively. The producers Snop 57 (his 17 daughters had average milk yield of 4224 kg for the first lactation with milk fat of 3.80%) and Muscat 8 (with an average milk yield of daughters of 4254 kg , milk fat - 3.83%) are also of significant value for the breeding work of this farm. According to the assessment results, the producer Aist 7 was assigned to the breeding category of A1 of milk yield improvers. Bulls Sazan 25 and Muscat 8 are also rated as daughters’ milk yield improvers and are categorized as A2 and A3. All bulls evaluated by comparing daughters to the breed standards are improvers of daughters’ milk yield (+ 454-1860 kg).

Telomere lengths correlate with fitness but assortative mating by telomeres confers no benefit to fledgling recruitment

Assortative mating by telomere lengths has been observed in several bird species, and in some cases may increase fitness of individuals. Here we examined the relationship between telomere lengths of Blue-footed Booby (Sula nebouxii) mates, long-lived colonial seabirds with high annual divorce rates. We tested the hypothesis that interactions between maternal and paternal telomere lengths affect offspring and parental survival. We found that relative telomere lengths (RTL) were strongly positively correlated between members of a breeding pair. In addition, RTL of both parents interacted to predict fledgling recruitment, although fledglings with two very long-RTL parents performed only averagely. Telomere lengths also predicted adult survival: birds with long telomeres were more likely to survive, but birds whose mate had long telomeres were less likely to survive. Thus, having long telomeres benefits survival, while choosing a mate with long telomeres benefits reproductive output while penalizing survival. These patterns demonstrate that while a breeder's RTL predicts offspring quality, assortative mating by RTL does not enhance fitness, and a trade-off between different components of fitness may govern patterns of assortative mating by telomere length. They also illustrate how testing the adaptive value of only one parent’s telomere length on either survival or reproductive success alone may provide equivocal results.

The Early Maternal Environment Shapes the Parental Response to Offspring UV Ornamentation

Parents allocate resources to offspring to increase their survival and to maximize their own fitness, while this investment implies costs to their condition and future reproduction. Parents are hence expected to optimally allocate their resources. They should invest equally in all their offspring under good conditions, but when parental capacity is limited, parents should invest in the offspring with the highest probability of survival. Such parental favouritism is facilitated by the fact that offspring have evolved condition-dependent traits to signal their quality to parents. In this study we explore whether the parental response to an offspring quality signal depends on the intrinsic capacity of the parents, here the female. We first manipulated the intrinsic capacity of blue tit (Cyanistes caeruleus) females through lutein-supplementation during egg laying, and we subsequently blocked the UV/yellow reflectance of breast feathers on half of the nestlings in each brood. However, we did not find evidence that the female intrinsic capacity shaped parental favouritism for offspring UV/yellow colouration, as there were no differences in parental feeding or sibling competition. However, we found that males were more responsive than females to nestling UV/yellow when rearing capacity was high, as indicated by the prey-testings (when a parent places a prey item into a nestling’s gape but removes it again). Furthermore, when considering a more integrative measure, offspring growth, we did find the expected interaction effect. In control nests, UV-blocked nestlings gained less body mass than their non-UV-blocked siblings, whereas in lutein-supplemented nests UV-blocked nestlings gained more mass than their siblings. Overall, our results emphasize the female’s environment at an early reproduction stage shaped the role of offspring UV/yellow during family interactions illustrating plasticity in parental feeding rules.