Breeding Bulls Research Articles

Productive longevity and lifelong productivity of daughters of Holstein bulls-producers with different variants of kappa-casein genotype

Reducing age of economic use of cattle is one of the problems of modern cattle breeding. One of the options for increasing productivity in cattle breeding is breeding for productive longevity, through the search and use of genetic markers. We have selected the genotype of the kappa-casein protein as a genetic marker. If the influence of allelic forms of this gene on milk productivity is well studied, then the question of its interaction with lifelong productivity indicators remains open. The purpose of our research was to determine the effect of the kappa-casein genotype of Holstein bulls on the longevity and lifelong productivity of their daughters. The analysis included the indicators of 1,476 animals with at least one completed lactation. Depending on the linear affiliation and genotype of the kappa-casein gene of the breeding bulls, their daughters were divided into 4 groups. The frequency of occurrence of the CSN3A allele in the studied bulls was 81.91%, the CSN3B allele — 18.09%. The highest frequency of occurrence of the desired CSN3B allele was in bulls of the Reflection Sovering line — 20.83%, which is 3.69% more than in bulls of the Vis Back Ideal line. The analysis of the life expectancy of animals showed that it turned out to be the longest in the daughters of bulls from the Reflection Sovering line (2.46 lactation) and especially with the CSN3B genotype — 2.59 lactation. The greatest lifetime milk yield (18,490 kg) was characterized by the daughters of bulls with the CSN3AB genotype in the Reflection Sovering line. Their superiority over animals from the same lineage, but with the CSN3AA genotype, was 1004 kg, the Vis Back Ideal line with the CSN3AA genotype was 1472 kg and with the CSN3AB genotype was 1343 kg. The highest average milk yield in 1 day of a cow’s life was also in animals of the Reflection Sovering line with the CSN3AB genotype — 9.05 kg.

Bull sperm morphology assessment varied by evaluator

Assessment of sperm morphology is an important part of bull breeding soundness evaluation (BBSE). Whereas the effects ofevaluator experience and evaluation method on the sperm morphology estimation were assessed in other species, no such studywas conducted for bulls. Our objectives were to assess the effects of evaluator experience and number of sperm assessed on BBSEoutcomes. A single eosin-nigrosin sperm morphology slide from individual semen samples, collected from 35 yearling bullswas used. In Experiment I, 6 individuals (3 board-certified theriogenologists [DACT] and 3 fourth-year veterinary students [VS])evaluated 100 sperm from 35 slides twice (at least 1 week between evaluations). In Experiment 2, 3 DACT evaluated 100, 200,and 400 sperm from the same 5 sperm morphology slides to determine if assessing a higher number of sperm would increase theagreement of morphologic characteristics. In Experiment 1, there was a difference (p < 0.0001) in the percent of sperm classifiedas morphologically normal between evaluator types (VS versus DACT). Furthermore, variation among evaluators affected spermmorphology assessments and bull breeding soundness evaluation classifications. Whereas the time needed to evaluate slides increased(p = 0.96) with increasing number of sperm assessed, there was no effect (Experiment 2) of number of sperm evaluatedon percent normal sperm, indicating that evaluating more than 100 sperm may not be justifiable. Further investigation on slidepreparation, microscope use, assessor experience, and continuing education/training is important to ensure the repeatability andvalidity of evaluating bovine sperm morphology.

Sperm Transcripts Associated With Odorant Binding and Olfactory Transduction Pathways Are Altered in Breeding Bulls Producing Poor-Quality Semen.

Spermatozoa carries a reservoir of mRNAs regulating sperm functions and fertilizing potential. Although it is well recognized that a considerable proportion of high genetic merit breeding bulls produce poor-quality semen, the transcriptomic alterations in spermatozoa from such bulls are not understood. In the present study, comparative high-throughput transcriptomic profiling of spermatozoa from good and poor-quality semen-producing bulls was carried out to identify the transcripts associated with semen quality. Using next-generation sequencing (NGS), we identified 11,632 transcripts in Holstein Friesian bull spermatozoa; after total hit normalization, a total of 544 transcripts were detected, of which 185 transcripts were common to both good and poor-quality semen, while 181 sperm transcripts were unique to good quality semen, and 178 transcripts were unique to poor-quality semen. Among the co-expressed transcripts, 31 were upregulated, while 108 were downregulated, and 46 were neutrally expressed in poor-quality semen. Bioinformatics analysis revealed that the dysregulated transcripts were predominantly involved in molecular function, such as olfactory receptor activity and odor binding, and in biological process, such as detection of chemical stimulus involved in sensory perception, sensory perception of smell, signal transduction, and signal synaptic transmission. Since a majority of the dysregulated transcripts were involved in the olfactory pathway (85% of enriched dysregulated genes were involved in this pathway), the expression of selected five transcripts associated with this pathway (OR2T11, OR10S1, ORIL3, OR5M11, and PRRX1) were validated using real-time qPCR, and it was found that their transcriptional abundance followed the same trend as observed in NGS; the sperm transcriptional abundance of OR2T11 and OR10S1 differed significantly (p < 0.05) between good and poor-quality semen. It is concluded that poor-quality semen showed altered expression of transcripts associated with olfactory receptors and pathways indicating the relationship between olfactory pathway and semen quality in bulls.

Evaluation of Semen Quality of Jeju Black Cattle (JBC) to Select Bulls Optimal for Breeding and Establish Freezing Conditions Suitable for JBC Sperm.

Simple SummaryJeju black cattle, a type of native Korean cattle characterized by black fur covering the entire body, inhabit Jeju Special Self-Governing Province, a World Natural Heritage Site. Although this breed was state designated as a natural monument in 2013 due to its characteristics and genetic traits, it is on the verge of extinction and thus there is a need to preserve this breed and further improve its traits. Therefore, we evaluated sperm motility, vitality, and morphology, which have long been considered good predictors of fertility in the absence of female infertility factors. Our findings showed that the semen of the JBC-A bull was superior to the semen of four other JBC bulls. Due to the aging of the population of JBC breeding bulls, strategies should be devised to improve sperm production in vivo.To optimize the reproduction of Jeju black cattle (JBC), freezing conditions for sperm were established and sperm motility, vitality, morphology, and fertility were evaluated to select the optimal bull for breeding. Semen samples from five JBC bulls were individually mixed with freezing medium at a final concentration of 1 × 108 sperm/mL and frozen in liquid nitrogen vapor at a height of 3 or 7 cm (referred to as 3 cm sperm and 7 cm sperm, respectively). When the freezing conditions were compared, the motility of 7 cm sperm was significantly higher than that of 3 cm sperm for the JBC-A bull. The motility, curvilinear velocity, straight-line velocity, and average path velocity of fresh and frozen–thawed sperm were the highest for the JBC-A bull. The vitalities of fresh and frozen–thawed sperm were the highest for the JBC-A/E and JBC-A bulls, respectively. The percentage of normal cells in fresh sperm was the highest for the JBC-D bull. The rates of the normal formation of two pronuclei and total sperm penetration were the highest in zygotes fertilized with sperm from the JBC-A bull. The sperm from the JBC-A bull had superior qualities and are thus the most appropriate choice for the preservation and reproduction of these endangered cattle.

A survey on the performance and status of disseminated elite N’Dama cattle breeding bulls at the multiplier tier of an Open Nucleus Breeding Scheme in The Gambia for the period 2011 to 2019

The objectives of this survey conducted in 2020 were to profile Multiplier farmers, assess the performance of disseminated N’ breeding bulls at the multiplier cattle herds, and inquire about cattle health and production challenges. Thirty-three farmers living in 33 villages in 5 regions of The Gambia who received 52 elite N’ breeding bulls from the West Africa Livestock Innovation Centre (WALIC) Nucleus tier were interviewed.&#x0D; &#x0D; The results showed that the disseminated bulls’ performance is generally satisfactorily as asserted by 28 respondents. Twenty-eight respondents reported that the bulls were healthier, 31 ascribed these bulls with stronger libido, 20 asserted that female offspring from these bulls produced more milk, and 26 claimed that offspring had a faster growth rate. A total of 473 calves have been sired by these bulls thus far. However, only 19 bulls are currently present at the multiplier herds due to the exit of 33 bulls arising from various causes. Cattle production challenges reported by farmers included decreasing grazing lands, rampant bush fires, and inadequate watering points; whilst listed health constraints included inadequate access to veterinary drugs and disease prevalence. The multiplication of the disseminated breeding bulls at the Multiplier tier has progressed well in terms of sired offspring, but further transfer to the Commercial Farmer tier is slow. This situation calls for more sensitization of farmers, increased visibility of the breeding programme, and utilization of other reproductive techniques such as artificial insemination to reach more cows for enhanced genetic improvement and productivity.

Non-gonadal linear type traits can discriminate reproductive ability of breeding dairy bulls.

Linear type traits are easily measurable phenotypic characteristics that help breed characterization, selection of animals for breeding and found to be associated with animals' performance. Unlike cows, there have been limited studies linking body linear traits with male reproductive ability and semen cryo-preservability of breeding bulls. Present study reported the age-related changes in body linear type traits in Frieswal (N=378) dairy bulls and its relevance with reproductive potentials of breeding bulls. Our results indicated that body frame size traits were significantly and positively correlated with gonadal linear traits. Among the selected body mophometric parameters body length, chest girth and head circumference were the important body linear type traits having capability to discriminate between bulls of frozen semen doses (FSD) and non-FSD categories. Discriminant function has been developed based on body linear traits of crossbred dairy bulls to find out males of superior reproductive potentials. Our finding provided evidence that body length (humerous tuberosity to tuber ischii) was the most powerful linear body trait associated with breeding bulls' reproductive ability and semen quality.

English

This work was conducted to study the breeding soundness of semen producing bulls, their semen quality to functional tests and the inter relationship of these functional tests with spermatozoa motility percentage for the semen produced at National Animal Genetic Improvement Institute (NAGII). A total of 14 breeding bulls (Boran = 4, Crosses of 75% Holstein Frisian &times; 25% Boran = 4 and Holstein Frisian = 6) with respective ejaculates of 35, 33 and 57 for semen quality evaluations were considered. After physical examination of bulls for breeding soundness, semen samples were tested for functional and structural (spermatozoa acrosome integrity, viability and hypo osmotic swelling reactivity) tests and spermatozoa motility percentage using subjective and objective (computer assisted semen analysis; CASA) evaluation methods, to see the correlation of functional tests with spermatozoa motility percentage. And in the study, nevertheless, significant differences between Cross and HF breeds were not recorded for the breeding soundness evaluation parameters and for most of the semen quality parametric test values; significantly (P &lt; 0.05) minimal and highest parametric values of the breeding soundness evaluation and semen quality were recorded in Boran and HF breeds, respectively. All the functional semen quality evaluation tests (HOST, acrosome integrity, sperm morphological defect and viability) were related in one or the other to the objective CASA individual spermatozoa motility evaluation; which were not true with subjective individual spermatozoa motility estimation. Therefore, conducting stringent breeding soundness evaluation for these breeds and evaluating their individual spermatozoa motility percentage using CASA system instead of subjective motility estimation can screen good quality semen and subsequently make possible to predict their fertility potential. Key words: Boran, correlation, cross-breed, Holstein-Frisian, semen.

Composition and diversity of the seminal microbiota in bulls and its association with semen parameters

The male bovine microbiota is a relatively unexplored area even though it has been shown to impact the fertility of not only the male but also the female. With this study, our aim was to evaluate the bacterial composition of semen from bulls with either satisfactory or unsatisfactory semen quality as represented by poor sperm motility and/or morphology. We hypothesized based on findings in human and other domestic animal studies, that the microbiota diversity and composition may be associated with decreased sperm quality. Semen samples from 45 beef bulls were collected, 32 of those bulls were classified as having satisfactory spermiograms according to Society for Theriogenology bull breeding soundness exam standards with the remaining 13 bulls being classified as unsatisfactory. Microbiota profiling was performed using 16S rRNA gene amplicon sequencing of the V4 region. The most abundant genera in the seminal microbiome include Bacteroides, Corynebacterium 1, Escherichia, Gemella, and S5-A14a (an uncultured bacterium from the Clostridiales order). Bulls with satisfactory spermiograms had a higher abundance of sequence types belonging to many genera including Bacteroides, S5-A14a, Trueperella, and two methanogenic archaea genera Methanosphaera and Methanobrevibacter. Comparatively, samples from bulls with unsatisfactory speriograms had greater abundance of sequence types belonging to Veillonellaceae, Campylobacter, and Methanobacterium. Network analysis was also performed for satisfactory and unsatisfactory samples and indicated that cooccurrence of microbial taxa was less common in the S group than in the U group. In the satisfactory group, Methanobrevibacter cooccurred with twelve amplicon sequence variants (ASVs), indicating that it may be important for maintenance of the microbiota in satisfactory samples, and members of this genus were enriched in the satisfactory group. Opportunistic pathogens such as Campylobacter, and Fusobacterium co-occurred with four and ten ASVs, respectively, in the unsatisfactory group, potentially indicating they are acting in synergy with other member of the microbial community, but only in the unsatisfactory group.

Low Birthweight Beef Bulls Compared with Jersey Bulls Do Not Impact First Lactation and Rebreeding of First-Calving Dairy Heifers—A Case Study in New Zealand

Dairy heifers in New Zealand are typically naturally mated by Jersey bulls to produce low-value non-replacement offspring sold for slaughter a few days after birth. Producing a beef-sired calf from a dairy heifer will increase the value of these calves for beef production but may compromise the subsequent career of the animals, in terms of milk production, rebreeding success, health, or survival of the heifer. This study aimed to determine the impact of low birthweight Angus and Hereford bulls versus breed-average Jersey bulls on the reproduction and production traits of first-calving dairy heifers. The experiment included 304 heifer-calf pairs over 2 years. Calves sired by Angus and Hereford bulls were 3.5–4.4 kg and 3.7–6.8 kg heavier than Jersey-sired calves and had a 4.2% and 9.3% incidence of assistance at birth for normally presented calves over the 2 years, respectively. No normally presented Jersey-sired calves were assisted. There was no difference in body condition score, pre-calving live weight, milk production, pregnancy rate, inter-calving interval, re-calving day, and 21-day re-calving rate of heifers mated to the different breeds of bulls. The results indicate that the Angus and Hereford bulls with low birthweight and high direct calving ease estimated breeding values (EBV) can be used to produce calves of greater value than Jersey-sired calves without impacting dairy heifer production. However, a small increase in assistance at calving could be expected.

Genotyping of HF Crossbred Breeding Bulls for A1/A2 Variant of β-Casein Gene

Background: The variants of β-casein (CSN 2) gene viz. A1 and A2 are supposed to be related with human health. Hence, to know the status of breeding bulls used for AI services were screened for A1 and A2 variants. Total 47 blood samples of crossbred breeding bulls from Frozen Semen Laboratory, Pune and Aurangabad were used for present work. Methods: The extraction of genomic DNA by phenol-chloroform method were carried out from the blood samples of 47 breeding bulls. Further, DNA based PCR-RFLP method was used to identify the A1, A2 variants. Pure DNA fragments of b-casein (CSN 2) gene were amplified by PCR using suitable pairs of primer to amplify 121 bp and 244 bp products. The primer used to amplify 244 bp was allele specific. The 121 bp fragment then subjected to restriction enzyme digestion. The restriction enzyme digestions resulted into two types of band pattern. The 244 bp fragment was used for validation of A1 and A2 allele of 121 bp. Result: Two types of genotypes i.e. A1A2 and A2A2 were revealed in the experimental population of HF crossbred breeding bulls. The genotypic frequency of A1A2 and A2A2 was estimated 65 and 35 per cent, respectively. The present frequency status of A1 and A2 allele in the breeding bulls may be suggested for planning future breeding strategy in dairy cattle.

Breeding Soundness Inspection and Production Features of Bullocks under Ecological Conditions in Free State Region, South Africa

Assessing the fertility of bullocks preceding to use as breeding animals make apparent economic if it were possible. Fertility is not possible predicted by means of a breeding soundness evaluation (BSE), but by the application of minimum standards to a set of accepted procedures, which supports informed decision makers to the breeding potential of the bullock. An bullocks found to satisfy these criteria in Central Performance Testing (CPT) known as Phase C, is reckoned to be breeding sound (BS). Furthermore, breeding success depends on the reproductive performance of both the cow and the bull. Breeding bull is likely to service a large number of heifers or cows in planned breeding season. The efficiency of a bullock can be based on the average daily gain (ADG) and feed conversion ratio (FCR) but poor breeding sound evaluation can be regarded as infertile. Bull breeding soundness evaluations (BSEs) are significant economic management of beef herd management and depends on adequate semen quality, physical soundness and serving capacity. Furthermore, assessment of scrotal circumference (SC), libido, testicular measurement and semen parameters often not done during a routine breeding soundness examination. The aim of this study was to depict using BSE whether bullocks would be fertile under Phase C. The relationship of BSE and production characteristics in central performance testing is challenging to identify fertility in bullocks within 112 given days of CPT. This study investigated performance data extracted from Integrated Registration and Genetic Information System (Intergis) managed by Agricultural Research Council Glen Bull Testing Centre. There were three breeds investigated, namely, Simmentaler, Santa Gertrudis and Limousin for the period of 2007 to 2017, were analysed to determine the dominance and importance of factors affecting breeding soundness classification.

Deep Metabolomic Profiling Reveals Alterations in Fatty Acid Synthesis and Ketone Body Degradations in Spermatozoa and Seminal Plasma of Astheno-Oligozoospermic Bulls.

Male fertility is extremely important in dairy animals because semen from a single bull is used to inseminate several thousand females. Asthenozoospermia (reduced sperm motility) and oligozoospermia (reduced sperm concentration) are the two important reasons cited for idiopathic infertility in crossbred bulls; however, the etiology remains elusive. In this study, using a non-targeted liquid chromatography with tandem mass spectrometry-based approach, we carried out a deep metabolomic analysis of spermatozoa and seminal plasma derived from normozoospermic and astheno-oligozoospermic bulls. Using bioinformatics tools, alterations in metabolites and metabolic pathways between normozoospermia and astheno-oligozoospermia were elucidated. A total of 299 and 167 metabolites in spermatozoa and 183 and 147 metabolites in seminal plasma were detected in astheno-oligozoospermic and normozoospermic bulls, respectively. Among the mapped metabolites, 75 sperm metabolites were common to both the groups, whereas 166 and 50 sperm metabolites were unique to astheno-oligozoospermic and normozoospermic bulls, respectively. Similarly, 86 metabolites were common to both the groups, whereas 45 and 37 seminal plasma metabolites were unique to astheno-oligozoospermic and normozoospermic bulls, respectively. Among the differentially expressed metabolites, 62 sperm metabolites and 56 seminal plasma metabolites were significantly dysregulated in astheno-oligozoospermic bulls. In spermatozoa, selenocysteine, deoxyuridine triphosphate, and nitroprusside showed significant enrichment in astheno-oligozoospermic bulls. In seminal plasma, malonic acid, 5-diphosphoinositol pentakisphosphate, D-cysteine, and nicotinamide adenine dinucleotide phosphate were significantly upregulated, whereas tetradecanoyl-CoA was significantly downregulated in the astheno-oligozoospermia. Spermatozoa from astheno-oligozoospermic bulls showed alterations in the metabolism of fatty acid and fatty acid elongation in mitochondria pathways, whereas seminal plasma from astheno-oligozoospermic bulls showed alterations in synthesis and degradation of ketone bodies, pyruvate metabolism, and inositol phosphate metabolism pathways. The present study revealed vital information related to semen metabolomic differences between astheno-oligozoospermic and normospermic crossbred breeding bulls. It is inferred that fatty acid synthesis and ketone body degradations are altered in the spermatozoa and seminal plasma of astheno-oligozoospermic crossbred bulls. These results open up new avenues for further research, and current findings can be applied for the modulation of identified pathways to restore sperm motility and concentration in astheno-oligozoospermic bulls.

Hematological condition of breeding bulls after a long winter period of operation in the conditions of the Udmurt Republic

Purpose: to study hematological parameters of blood in bulls-producers of dairy breeds on the day of semen collection in the Udmurt Republic after a long winter period of operation, depending on the breeds, age and place of selection.Materials and methods. The work was performed at the Federal Research Center for Animal Husbandry named after Academy Member L. K. Ernst on the basis of AO "Udmurtplem" of the Udmurt Republic in the period from 2020 to 2021 on dairy bulls (n=20) aged 15-69 months, including a purebred Holstein breed of domestic selection (n=6), a Holstein black-and-white breed of European selection (the Netherlands, n=6), a black-and-white breed with blood transfusion on Holsteins on at the level of 94-98% (n=8). The content of white blood cells, red blood cells, hemoglobin and hematocrit, depending on age and breed, was studied on the ABC VET hematological analyzer on the day of taking the seed.Results. It was found that on average, in 20 bulls aged 15-69 months, the level of white blood cells was at the level of reference values of 8.8±0.25 x 109/l, red blood cells 10.3 x 1012/l, which is 50% more than the reference values. The concentration of hemoglobin is 128.0±2.92 g/l, hematocrit is on average 54.3%, with a norm of 24-46%. Breeding bulls at a reliable level, differing in age, showed that some animals had high indicators for red blood cells of 10.3±0.26 x 102, for hematocrit of 54.3% against 24-46% of reference values. Also, according to hematological indicators, there was a tendency to increase the concentration of hemoglobin and hematocrit in European-bred bulls.Conclusion. The study of the variability in hematological parameters depending on the selection showed that there is no significant difference in leukocytes and all indicators are at the level of reference values, and in erythrocytes more than 50% than the highest indicators. The highest hemoglobin values were at the level of 141-156 g/l instead of 128 g/l according to the highest reference values. Hematocrit also showed high max values in all groups in comparison with the reference values of 59-66% versus 46% in the norm. It is necessary when analyzing hematological blood parameters in addition to the average statistical indicators (M+m) also, monitor the variability (min-max) in order to obtain more objective information.

Structure of the holstein dairy cattle subpopulation in Russia by locus CSN2 and CSN3

Purpose: to determine the potential of the Russian subpopulation of the Holstein breed in relation to selection by loci of beta-and kappa-casein.Materials and methods. For loci CSN2 and CSN3, 1,539 Holstein cattle were genotyped, including 1,242 cows and heifers and 297 sires, and information on CSN2 and CSN3 genotypes of 297 US bulls was analyzed (World Wide Sires, Ltd).Results. It has been established that in the last two years there has been an increase in the percentage of sires in WWS with CSN2 genotypes A2A2 and CSN3 genotypes BB. Thus, sires allele frequency in the 2019 catalog was 0.51 and 0.29, respectively; and in the 2021 catalog was 0.68 and 0.31, respectively.Genotyped sires of domestic breeding organizations, which are mostly foreign origin, were characterized by predominance of the A2 allele CSN2; in this group the frequency of the allele was 0.63. However, the CSN3 B allele in the group of sires belonging to domestic organizations was found with a frequency of 0.34, which is 1.6 times lower than that of sires of American origin.In the genotyped group of Holstein cows and heifers (n = 1242) belonging to 3 large farms in the Krasnodar Krai, the gene frequency CSN2 allele A2 was minimal (0.57), and the CSN3 allele B (0.40) was higher than the allele frequency in the sires group of domestic breeding enterprises.Conclusion. At present, Russian breeding enterprises and farms are lagging behind in these indicators, however, by conducting targeted selection in accordance with the indicated trend, by selecting the appropriate breeding bulls, it is possible in the next generation to increase the proportion of animals carrying valuable genotypes.

Hormonal biochemical monitoring at bull-producers of different breeds in the conditions of the Central Black Economic District

Purpose: To conduct a comprehensive monitoring of bulls of different breeds in the summer in a comparative perspective to the study of protein-lipid and mineral metabolism, as well as to determine hormonal status on the content of endogenous hormones: testosterone, estradiol, cortisol and serum thyroxine per day taking seed.Materials and methods. For the first time in a Chernozem region of the Russian Federation (Voronezh region) was carried out comprehensive monitoring of bulls of red-motley Holstein (n = 16), Red-and-White (n = 8) and Simmental (n = 6) rocks in the same time of year (summer) of the protein-lipid and mineral metabolism, as well as the level of endogenous hormone (testosterone, estradiol, cortisol, thyroxine) and their cholesterol precursor in comparative aspect, immediately after taking the seed. Age range bulls ranged from 2 to 11 years. General monitoring was conducted on 23 indices of blood serum 3 rocks. The studies were conducted by modern methods, using modern equipment and reagents.Results. At Red Pied Holsteins an increase of total protein 100.45 g / L versus 92 g / l in normal (above the norm of 9.2%, as compared with red and White breed at the level of 11.3%). A similar increase in concentration in the blood of Holstein bulls red-White breed recorded on globulins, 68.87 g / l to 63 g / l in normal (above the norm of 9.3%), and with respect to the red-and-White breed 17, 6%. Also notes the high content of AST bulls red-motley Holstein against the red-and-White 18%, but within the reference range. Condition protein and lipid metabolism in sires only differed in content of creatinine, which amounted to 165.04 micromol / l against 163 mmol / l in normal, 1.6% higher as compared to the red and white breed this index was higher 18.7%. According to the content of testosterone highest rate was observed in bulls red-White breed 54.73 ± 9.51 nmol / l, is 10.2% more than in bulls red checkered-Holstein and 12.45% compared with Simmental breed. Similarly, in terms of serum cortisol - 355.60 ± 39.2 nmol / l in the red-bulls White breed that more than 2-fold compared with bulls Red Pied Holstein and Simmental. The difference is statistically significant at P ≤ 0,01. According to the content of estradiol relatively low levels recorded in the bulls of red-motley breed - 0.265 nmol / L vs. 0.301 nmol / L in red bulls-motley Holstein, and 0.332 nmol / L - Simmental, is lower by 13.6% and 25 , 3%, respectively.Conclusion. It was found that substantially all of the studied parameters in bulls 3 breeds are at reference values, and this gives grounds to assume that all of these breeds are well adapted to the conditions of Black Soil.

Economic efficiency of using high energy of bulls’ growth

The article presents the results of research on the comparative assessment of the growth, development and meat productivity of calves and castrates of Kalmyk and Simmental breeds under the same conditions of feeding and maintenance and identification of ways to increase the profitability of beef production by using the physiological state of young animals. The experimental young animals received the same amount of feed by volume and the composition of the diet was the same. As a result of the conducted studies, it was found that the live weight of bulls of both breeds with their intensive cultivation exceeded the mass of castrates in all age periods. After weaning, there was no significant difference in the live weight of calves of the Kalmyk and Simmental breeds, which had a live weight of 255.6 and 253.9 kg, respectively, and by the age of 15.5 months, many bulls of both breeds reached from 500 to 520 kg. Castrates of both breeds grew less intensively. However, in the final period of fattening, they gave a high average daily increase (more than a kilogram). The Kalmyk castrati were less demanding of coarse feeds and used them better. According to the indicators of the control slaughter, it can be noted that the mass of carcasses of bulls of both breeds is the same, and castrates had such a mass of carcasses only at the age of 18 months. At the same time, the carcass mass of castrates of the Simmental breed was 7.6 kg lower than the carcass mass of Kalmyk castrates. Bulls and castrates of both breeds gave an exceptionally high slaughter yield. At the same time, animals of the Kalmyk breed have a higher slaughter yield due to the large accumulation of internal fat. An analysis of the data on the efficiency of beef production when selling one head of bulls at 15-16 months of age compared with castrates shows that the level of profitability per sold head is higher for both breeds by 1.8 and 4.3%, respectively. Thus, due to the peculiarities of the hormonal status of bulls, compared with castrates, they have an increased ability to grow, protein synthesis and reduced fat formation. However, castrates can also be grown extensively and for a longer time in less favorable conditions and receive high-quality beef, steers – only intensively and for a limited period (up to 16-18 months).

Meat productivity and biological value of meat in bulls of various breeds

Our study presents the results of a comparative assessment of meat productivity and biological value of meat in bulls of various breeds. The work was carried out at OJSC named after N.E. Tokarlikov of the Almetyevsk region of the Republic of Tatarstan using industrial technology in three groups (18 heads in each group): I - Simmental, II - Black-and-White and III - Hereford. Relatively high rates of meat productivity and qualitative characteristics of the meat were determined in Hereford bulls: meat weight was 1.7 and 4.5% more compared with Simmental and Black-and-White peers. The meat index in animals of the meat direction (4.59) is higher by 7.5 and 5.5% compared to analogues of I and II groups. The specific gravity of the protein did not have significant differences (18.60-19.05%). At the same time, a higher level of fat was noted in meat from beef cattle - by 1.05 and 1.51%. They also favorably differed in essential amino acids content in the proteins of muscle tissue. Their amino acid score was above 100%. A more balanced ratio of essential amino acids was established in individuals of beef cattle when calculating the biological value of the protein. Meat from animals of Hereford breed was differed by relatively high level of non-essential amino acids - 318.8 mg per 1 g of protein, which is 1.3 and 10.4% more than in the peers of the first two groups.

Variability of indicators of milk productivity in cows of different genotypes and with different index of lactation constancy

at present, the livestock industry in Russia is aimed at obtaining highly productive cows, taking into account their individual characteristics. It is known that animals with high genetic potential react to certain environmental changes especially. Hence, phenotypic evaluation will not help select the best cows with high genetic potential. Therefore, the assessment of individual qualities requires a new approach, which can be safely attributed to various kinds of indices, among which the index of lactation constancy occupies a special place. Such an index score fully characterizes the genotype. Any herd is characterized by a large genetic diversity of individuals. The variability of milk productivity traits determines this diversity, therefore, among highly productive cows there are those that are able to maintain the amount of milk yield and other valuable traits and be able to pass them on to their descendants. The main goal of breeding is aimed at identifying cows with such a valuable genotype and further their widespread use within the farm. Cows, daughters of different breeding bulls with a high index of lactation constancy, can serve as a starting point in the selection of producers with further recommendation for their use in different populations with different levels of productivity.

Identification of Pentatrichomonas hominis in preputial washes of bulls in Brazil.

The parabasalid Pentatrichomonas hominis is generally considered to represent a symbiotic component of the gastrointestinal microbiota in a wide variety of vertebrate hosts including humans. Nevertheless, a limited number of studies have raised the possibility that it may act as a pathogen of humans, dogs, and pigs and that some human infections may have a zoonotic origin. Data from North America revealed an association between P. hominis and the bovine urogenital tract, principally in bulls and rarely in cows. The importance of this observation is linked to possible interference in the accurate diagnosis of the economically important venereal pathogen Tritrichomonas foetus. The current study employed culture-based and molecular methods to examine the preputial cavities of four breeding bulls, raised in open pasture in southeastern Brazil, for the presence of trichomonads. Motile protozoa were isolated from three of the bulls and were definitively identified as P. hominis based on nucleotide sequencing of polymerase chain reaction (PCR) amplicons derived from the ribosomal RNA operon (ITS1-5.8S rDNA-ITS2) of the parasite. The potential implications of these findings for bovine and human health are discussed.

Effect of bull-calf management system on meat productivity

Traditional technologies for the production of beef in the conditions of industrial production of livestock products in the middle of the 20th century were schematically transferred from dairy cattle breeding and do not take into account the behavioral characteristics of animals. The traditional approach to the cultivation of young animals involves a stall-and-loose keeping system, mechanized distribution of feed and manure cleaning. Under such conditions the labor costs for the production of 1 kg of beef are within 15-30 man-hours, the total specific weight of feed, electricity, fuel and lubricants, depreciation costs of livestock buildings and technological equipment in the cost structure of this product reaches 50-55%. Beef production remains unprofitable regardless of animal breed – the cost of 1 kg of meat is 1.5-2 times higher than the sales price, which hinders further development of the industry. The paper shows the results of the assessment of meat productivity of bulls of various breeds when raised using traditional and low-cost technologies. Research results are relevant for beef production in steppe regions.