The work aims to study the features of herd reproduction in the conditions of a modern specialized unit for growing repair young animals.
The studies were carried out in the conditions of Megaferma OOO in the Kuznetsky region, which is part of the Rusmolco Company in the Penza region, on the number of animals in the modern herd reproduction center. The object of the research was the replacement heifers of the Holstein breed; the subject of the research was: live weight of heifers in different technological periods and the efficiency of insemination of heifers with sexed and ordinary sperm.
The studies show the dynamics of live weight of the Holstein heifers of different origin (Holland, the USA, Russia) during directed growing; the achievement of live weight of 350 kg was established by the period of the first insemination at the age 12 months; the Dutch heifers had a higher growth rate during all growing periods.
The results of studies indicate that when using sexed semen, the pregnancy rate of heifers from the first insemination was 54.5%; 82.5% of heifers were received from the studied livestock, which is 29.5% more than from the insemination with ordinary semen. When inseminating with sexed semen of heifers of different origins (Hungary, Germany, Russia), the existing differences in the experimental groups were found. The pregnancy rate from the first insemination in the studied livestock ranged from 48.7 to 59.7%, and the yield of heifers - from 77.5 to 89.4%.
Such indicators are consistent with the international practice of using sexed semen and with the guarantees of the semen producer. Consequently, an increase in the number of heifers in offspring allows breeding farms to abandon the acquisi-tion of expensive breeding young stock.
This paper comparatively examines the genotypic features of the development of muscle groups and individual muscles of the carcass of purebred Simmental bulls, and bulls crossbred with Simmentals: ½Simmental×½Red Steppe and ½Simmental×½Black and White bulls at the age of 18 months. It was found that in terms of the absolute mass of individual muscles of the spinal column, the highest level of parameters was characteristic of the bulls of group III, except for m. multifidus, where the biggest mass was shown by group I. The smallest mass, both of individual muscles, and in the group as a whole, was observed in crossbred bulls of group II. The analysis of the development of individual muscles of the shoulder girdle indicates that purebred bulls of group I exceeded the bulls in groups II and III in terms of the mass of m. brachiocephalicus, m. serratus ventralis, and m. pectoralis profundus. The bulls of group III were characterized by an advantage over the bulls of group II in the mass of m. pectoralis profundus, m. serratus ventralis, and m. brachiocephalicus. A comparative assessment of the development of individual muscles of the thoracic limb indicates that crossbred bulls of group III were distinguished by an advantage over the bulls of groups I and II. The differences in the mass of both individual muscles and between groups I and II were significant. A similar pattern of intergroup differences manifested itself in the development of both individual muscles and the pelvic limb as a whole.
АННОТАЦИЯ В статье представлена сравнительная оценка показателей роста и экстерьерных особенностей чистопородных бычков айрширской и швицкой пород и их помесей с герефордами. Наибольшей живой массой, отличались швицко-герефордские помеси. В конце опытного периода они достигли живой массы 429 кг, и их превосходство составило над I, II, и III группами -48; 38 и 20 кг соответственно. По уровню среднесуточных приростов во все возрастные периоды эти животные значительно превосходили сверстников других подопытных групп. По типу телосложения помесные бычки обеих групп приближались к животным специализированных мясных пород. Они отличались компактным типом телосложения, большей живой массой и величиной широтных промеров. В целом, влияние герефордской породы выразилось в более интенсивном росте и улучшении экстерьерно-конституциональных особенностей животных.
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