Dairy Cattle Breeding Research Articles

Improvement of the Meat Quality of Holstein Bulls Fed a Diet Enriched with Oregano Oil

Beef is a dominant meat commodity produced mainly from beef cattle breeds. Dairy cattle breeds are reared for milk production, but their calves could be raised to produce high quality meat subject to designated feeding. The objective here was to investigate the role of oregano oil-enriched diets on the quality characteristics of meat produced by Holstein bulls. Fifty Holstein bulls, aged 12 ± 2 months and with an average weight of 365 ± 60 kg, were used. They were equally allocated in two experimental groups (n = 25). One group (group CON) was offered a basal diet and the other (group OREG) the same diet enriched with 50 mg/kg DM of oregano oil, for a period of 90 days. Afterwards, meat samples were subjected to microbiological (1 h after slaughter), physicochemical (1st and 15th day after slaughter), and sensory analyses (15th day after slaughter). The beef of group OREG is characterized with improved color parameters and a lower malondialdehyde (MDA) production rate and content (68.52 ng/g versus 105.91 ng/g, p = 0.01). The sensory evaluation of beef revealed higher scores for group OREG in flavor (3.88 versus 3.17, p = 0.0007) and color (3.87 versus 3.21, p = 0.001), as well as higher nutritional value, which was associated with significantly higher levels of alanine, arginine, aspartic acid, histidine, isoleucine, leucine, lysine, valine, and total amino acids (p < 0.05). Thus, the results suggest that the quality of the meat of Holstein bulls can be improved when they are fed a diet enriched with oregano oil.

Assessment of the Production System of Indigenous Dairy Cattle Breeds in Metekel and Some Parts of the Awi Zone, Ethiopia

This study was conducted in Mtekel and some parts of the Awi Zone to assess indigenous dairy cattle production patterns in the study area. The majority of respondents (98.3% and 53.95%) were male and literate, respectively. Land holdings varied significantly, ranging from landless households to those owning up to 280 hectares. The predominant farming activity was mixed farming (69%). Agriculture was the primary source of income for 79.3% of respondents across all districts. The trend in cattle productivity was increasing, with the main objective of cattle production being income generation. Cattle were the major contributors to household income, followed by crop production, and were considered the most important livestock species in the area. Crop residues and communal grazing lands were the primary feed resources during the dry and wet seasons, respectively. Overall, cattle production was identified as the major income source, a significant contributor to household income, and a multifunctional agricultural activity for the farming community in rural, peri-urban, and urban areas of the study area. The relevant authorities should focus on improving cattle production in terms of feed, breeding, health, and management practices to enhance productivity and improve livelihoods.

Influence of average daily gain of heifers on the age of first insemination

The purpose of this study is to establish the influence of average daily gain (ADG) of heifers at different periods of their development on the age of 1st insemination (A1ins) at 12, 13, 14, 15, 16, 17, 18 months and older and milk yield of first-calving cows for 305 days of lactation according to a sample (n=1289) formed from the Seleсs database of one of the breeding plants in the Leningrad region for breeding the Ayrshire breed of dairy cattle. On average for the sample, the correlation coefficient of milk yield with A1ins indicates a negative relationship between these two characteristics (-0.218), a positive correlation of milk yield with live weight of 1st insemination LW1ins (+0.101) with a negative connection with ADG (-0.110). It was revealed that in all age groups of heifers there is a decrease in ADG at the age of 2 months, and the intensity of further development of heifers depends on ADG at the age of 3, 4, 5 months, at a level of over 800 g, contributes to the achievement of A1ins from 12 to 14 months. At the same time ADG at the age of 9—12 months should be at least 800 g. However, even with ADG 800—900 g at the age of 3—5 months, but when these indicators decrease at 9—12 months below 800 g, A1ins increases to 15—16 months. Low ADG at the age of 3—5 months and at the level of 600 - 700 g at the age of 9—12 months increases A1ins to 17 months and older. Thus, for an earlier A1ins and a high level of productivity in the 1st lactation, one should pay attention to the development of heifers at the age of 3—5 months, maintaining the ADG at a high level (more than 800 g) and avoid low weight gain at 9—12 months (less than 800 g).

Selection indexes in terms of functional features in modern dairy cattle breeding in Europe

Abstract The increase in demand for dairy products requires continued progress in dairy farming for a sustainable supply. Europe, known as the world's leading milk producer, plays a key role in meeting this growing demand. Modern dairy farming has moved beyond its historical focus on milk yield and now focuses on functional traits such as udder health, fertility and calf survival. As a result, selection indicators have become essential tools, combining multiple attributes to support selective decisions. However, these rates show considerable variability across countries, reflecting their distinct breeding goals. Poland's production and functionality (PF) Index emphasizes production and functional traits to enhance dairy cattle. Portugal uses the total economic merit (M€T) and total performance index (IPT) for a broader assessment covering a wider range of traits. Ukraine is transitioning towards a more comprehensive breeding system incorporating stress tolerance and longevity. Factors such as climate change and the need for sustainable practices drive this evolution, underscoring the economic importance of traits beyond mere production. Future trends may include features such as feed efficiency, methane emissions reduction and stress resistance. Diverse breeding objectives across countries lead to different selection index constructions, essential for effective selection, ranking and breeding of superior individuals. This comprehensive review offers insight into constantly evolving dairy farming strategies in Europe, with a focus on Poland, Portugal and Ukraine, while highlighting the key role of functional traits in shaping the future of dairy farming.

Genetic Evaluation of Monthly Test-Day Milk Yields of Jersey Crossbred Cattle Under Farmers' Production System in Tamil Nadu, India.

Tamil Nadu, a state in southern India, is bereft of any native dairy or dual-purpose cattle breeds, and the state depends chiefly on crossbred cattle for milk production. Jersey crossbred cattle account for 90% of the state's milk production. This genetic evaluation study aimed to assess milk production traits, including test-day milk yields (TDMYs), total lactation milk yield (TMY), and 305-day milk yield (305MY), in these cattle reared under farmers' conditions. Data on monthly TDMYs (TDMY1 to TDMY10) of Jersey crossbred cows (n = 75,627) reared by the farmers over 11 years (2012-2022) were collected for evaluation. The influence of non-genetic factors viz., location (agroclimatic zones), period and season of calving, and parity on TDMYs, TMY and 305MY were assessed, and the variance and covariance components for genetic parameters (heritability and genetic correlation) of the traits were estimated by the method of restricted maximum likelihood (REML) under a multivariate animal model and by a random regression model (RRM). The overall means of various TDMYs ranged from 4.98 (TDMY10) to 9.95 kg (TDMY2), and for TMY and 305MY, the means were 2480.33 and 2393.71 kg, respectively. The heritabilities estimated by the multivariate animal model for TDMYs were moderate and ranged from 0.26 ± 0.02 to 0.37 ± 0.02 and the estimates were less variable throughout lactation, while the estimates obtained by RRM were medium to high and ranged between 0.29 ± 0.01 and 0.67 ± 0.02 for milk yield on day 5 to 305 (DIM 5-DIM 305). The heritabilities estimated for TMY and 305MY were 0.43 ± 0.02 and 0.43 ± 0.02, respectively. The estimates of heritability for mid-lactation yields were comparatively less than those at the beginning and the end of lactation. The moderate to high estimates of heritabilities for TDMYs, TMY, and 305MY obtained in the present study offer ample scope for improving milk production through selective breeding. Genetic correlations between TDMYs estimated by the multivariate animal model were positive and high, with a range between 0.75 ± 0.03 and 0.99 ± 0.00. Considerably higher estimates (0.98-0.99) were observed between adjacent TDMYs showing strong genetic associations. By RRM, genetic correlations estimated between DIMs were positive (except for DIM 5 with DIM 125 to DIM 185 and DIM 125 with DIM 305), and the magnitude of genetic correlation decreased with an increase in the interval between the DIMs. The high genetic correlation observed between the TDMYs (in the early stage of lactation) and total lactation milk yield suggested that these test-day yields could be used favorably for the early selection of cows for milk production, which facilitates reduction in the generation interval and consequently increases the annual genetic gain for the milk production traits.

Genome-wide association study for milking speed in Fleckvieh cattle

Milking speed is an important trait influencing udder health of dairy cows as well as labor efficiency. Yet, it has received little attention in genomic association studies. The main objective of this study was to determine regions and genes on the genome with a potential effect on milking speed in Fleckvieh (dual purpose Simmental) cattle. Genome-wide association studies were conducted using de-regressed breeding values of bulls as phenotypes. Six SNP on 4 autosomes were significantly associated with milking speed for additive effects. Significant regions on BTA4 and BTA19 correspond with findings for other dairy cattle breeds. Based on the observation of Fleckvieh breed managers, variation of milking speed in batches of daughters of some bulls is much higher than in daughter groups of other bulls. This difference in within family variation may be caused by transmission of alternative alleles of bulls being heterozygous for a gene affecting milking speed. To check on this, we considered standard deviation of yield deviations in milking speed of half-sib daughters as a new trait and performed GWAS for dominance effects. One signal on BTA5 passed the genome wide Bonferroni threshold that corresponded to the significant signal from standard GWAS on de-regressed breeding values. The key conclusion of this study is that several strong genomic signals were found for milking speed in Fleckvieh cattle and that the strongest of them are supported by similar findings in Brown Swiss and Holstein Friesian cattle. Milking speed is a complex trait whose sub-processes have not yet been elucidated in detail. Hence, it remains a challenge to link the associated regions on the genome with causal genes and their functions.

Association of SPP1 and NCAPG genes with milk production traits in Chinese Holstein cows: polymorphism and functional validation analysis.

Milk production traits play an important role in dairy cattle breeding, and single nucleotide polymorphisms can be used as effective molecular markers for milk production trait marker-assisted breeding in dairy cattle. Based on the results of the preliminary GWAS, candidate genes SPP1 and NCAPG associated with milk production traits were screened. In this study, the aim was to screen and characterize the SNPs of SPP1 and NCAPG genes about milk production traits. Two SNPs and one haplotype block of the SPP1 gene and four SNPs and one haplotype block of the NCAPG gene were obtained by amplification, sequencing and association analysis, and all six SNPs were located in the exon region. Association analysis showed that all six SNPs were significantly associated with milk protein percentage. Linkage disequilibrium analysis showed that 2 SNPs of SPP1 (g. 36,700,265 C > T and g. 36,693,596 C > A) constituted a haplotype that correlated with milk protein percentage, and the dominant haplotype was H2H2, which was CCTT. 4 SNPs of NCAPG (g. 37,342,705 C > A, g. 37,343,379 G > T, g. 37,374,314 C > A and g. 37,377,857 G > A) constituted a haplotype associated with milk protein percentage, 305-days milk protein yield and 305 days milk yield. Tissue expression profiling results revealed that SPP1 and NCAPG had the highest expression in mammary tissue. Interference with SPP1 and NCAPG inhibited the proliferation of Bovine mammary epithelial cells. (BMECs), down-regulated the expression of PCNA, CDK2 and CCND1, up-regulated the expression of BAX and BAD, and promoted apoptosis. Reduced triglyceride synthesis in BMECs, down-regulated the expression of DGAT1, DGAT2, LPIN1, and AGPAT6.SPP1 and NCAPG are involved in the synthesis of milk proteins, and interfering with SPP1 and NCAPG decreased the secretion of β-casein, κ-casein, and αs1-casein, as well as up-regulated the CSN2 and CSN3 expression. The above results indicate that the SNP loci of SPP1 and NCAPG can be used as potential molecular markers to improve milk production traits in dairy cows, laying the foundation for marker-assisted selection. It also proves that SPP1 and NCAPG can be used as candidate key genes for milk production traits in dairy cows, providing new insights into the physiological mechanisms of lactation regulation in dairy cows.

Estimation of genetic parameters for reproductive traits in Korean dairy cattle.

In Korea, dairy cattle breeding programs have historically prioritized productive, conformation traits, leading to positive improvements, yet reproductive traits have lagged in development. This study was conducted to develop the breeding program of key reproductive traits in the Korean dairy cattle population. Utilizing data from 7,596 farms and over seven million observations, we conducted quality control to rectify manual entry errors and selected traits in line with international genetic evaluation standards. Traits analyzed included heifer conception rate (HCR), interval from calving to first insemination (CF), cow conception rate (CCR), interval from first to last insemination (FL), and days open (DO). Genetic parameters were estimated using a single trait animal model for HCR and a multiple lactation animal model for CF, CCR, FL, and DO, considering contemporary group of herd-insemination year, insemination month, and monthly age (MA) as fixed effects. Results showed low heritability estimates, ranging from 0.007 to 0.035 across different traits and lactations. Theoretical reliability appears to be low on average due to the influence of heritability, but it showed sufficiently high reliability in some sires (over 0.8). In terms of genetic and phenotypic trends, capacity for reproductive traits declined for a long time until around 2014. In recent individuals, improved trend can be found. This study addressed the critical need for enhancing reproductive efficiency to complement the existing breeding goals, thereby supporting sustained economic viability in the dairy industry. The results underscore the need for improved data quality and methodological adjustments for reproduction records to enhance the genetic evaluation of dairy cattle in Korea.

Comparative Genetic Study of Local and Introduced Cattle Breeds of Khizi District of Azerbaijan Republic

A comparative genetic study of local and introduced breeds of cattle in the farms of the Khizi district was carried out. Cattle of various breeds are kept on the territory of the region at enterprises of legal entities and individuals, in farms belonging to individual owners. Introduced breeds of cattle, beef and dairy cattle make up 0.0029% of the total livestock. Simmental (25%), Holstein-Frisian (27%), Brown Swiss (12%) and Aberdeen-Angus (7%) breeds are derived from introduced beef and dairy cattle. For a comparative study of the genomes of local and introduced breeds of cattle, blood samples were taken, DNA was obtained and prepared for further analysis.

Current state of dairy cattle breeding in the Saratov region

Studies of the state of the dairy cattle breeding industry for the last 5 years in the Saratov region in the context of the average indicators for the same breeds in the Russian Federation and the Volga Federal District showed that the Holstein breed of black-mottled breed surpasses the black-mottled, Simmental, red-mottled, Kostroma breeds. In the Saratov region for the analyzed period there is not a good situation on the black-mottled breed, which stopped breeding in 2021, but the positive dynamics was that in 2021 brought and began to breed the Kostroma breed. In terms of milk production in the Saratov region the black-mottled Holstein breed stands out, its milk yield is 11308.6 kg, black-mottled -7461.3 kg, red-mottled - 6918.8 kg, which exceeds the average figures for the Russian Federation by 2012.4, 163.1, 40.2 kg and the Volga Federal District by 2108.2, 504.3 kg, respectively, but the animals of red-mottled breed are inferior to the Volga Federal District by 877.8 kg. Simmental, red-spotted breeds have high average indicators of fat in comparison with RF and PFD by 0,05;0,14 and 0,11; 0,19 kg and protein by 0,03;0,01 and 0,04; 0,02 %, respectively. Evaluating the live weight indicators of cattle bred in the conditions of Saratov region such breeds as: black-and-breed, Simmental, red-and-breed, Holstein black-andbreed, Kostroma breeds, the maximum live weight in animals of black-and-breed - 565.6 kg and the minimum 450.0 kg - in kostroma breeds. Simmental and black-and-brown breeds surpass with a good enough gap the average indicators of the Russian Federation and the Volga Federal District in terms of live weight by 7.2; 12.2 and 4.4; 20 kg. The number of red-breed, Kostroma, Holstein black-breed animals is inferior to the average data on live weight in the Russian Federation and the Volga Federal District.

Short communication: Do veterinary diagnoses coming from electronic recording system of veterinary treatments have the potential to be used for breeding in small populations? The case of the dual-purpose Alpine Grey cattle breed

In cattle breeding, emphasis has historically been placed on productive traits, so-called primary traits, while health and fitness traits have been overlooked due to their low heritability and partly negative genetic correlations with productivity. In addition, the recording of phenotypes caused problems due to a lack of high-quality information and / or high costs of recording. This oversight has additionally led to increased incidences of fertility issues and health problems in cattle populations, resulting in economic losses and consumer concerns regarding animal welfare and food safety. This study investigates the potential use of veterinary diagnoses, collected via the Italian electronic recording system of veterinary treatments, for breeding decisions in the local dual-purpose Alpine Grey cattle breed for which the consideration of functional traits in breeding has also become imperative over the last years. The dataset comprised 97 821 records spanning from 2021 to 2023, representing 8 273 individuals and 18 110 lactations of the Alpine Grey breed. Each record documented the administration of treatments for mammary, respiratory, and urogenital pathologies. After data editing and model development, heritability estimates were obtained for each pathology using univariate linear animal models and gibbs sampling algorithms. Results indicate that mammary pathologies affected the highest number of cows (11%), followed by respiratory (4%) and urogenital (5%) pathologies. Heritability estimates ranged from 0.01 to 0.04 across all traits, confirming generally low heritability values. Respiratory pathologies exhibited the highest heritability (0.04; sd 0.04), followed by mammary (0.03; sd 0.01) and urogenital (0.01; sd 0.01) pathologies. This study, although preliminary, provides valuable insights into the health status of local dual-purpose Alpine Grey cattle and highlights the potential of considering veterinary diagnoses for improving animal health and welfare in dairy cattle breeding. However, the low heritability of these traits, which is consistent with literature data, clearly shows the current limitations of using them for breeding. Further, the diagnostic key of the Italian electronic recording system of veterinary treatments should be specified for the use of health data for breeding purposes, as it is formulated in too general manner in its current form. Nevertheless, their significance for animal welfare and economic sustainability underlines the need for their consideration in dairy cattle breeding. Therefore, further research with larger sample sizes and consideration of additional indicators, such as somatic cell counts, is recommended to enhance the accuracy of genetic evaluations and improve breeding strategies for sustainable cattle production.

Состояние породных ресурсов крупного рогатого скота в генофондных хозяйствах России

Abstract. The purpose of the research was to assess the effectiveness of the production use of small breeds of cattle bred in the country's gene pool farms. Methods. The purpose set in the study was achieved through the use of methods of analysis and generalization using special scientific literature on the problem being analyzed, a yearbook on breeding work in dairy cattle breeding on farms of the Russian Federation, and periodicals. Object of study: cattle breeds of gene pool farms in Russia (Bestuzhev, Mountain cattle of Dagestan, Istoben, Caucasian brown, red steppe, Tagil, Yakut cattle, Pechora type of Kholmogory breed). Results. Among all the breeds bred in gene pool farms, the latest ripening ones, which took the longest to reach the age of first calving, were Yakut cattle, as well as individuals of the Istoben and Red Steppe breeds, in which it varied within 33.4–35.3 months. It should be noted as a positive pattern that the animals of the Tagil breed achieved the analyzed indicator early, which was 26 months. The optimal duration of the period from calving to fertile insemination was distinguished by cows from the gene pool farms of the Republic of Dagestan – Mountain cattle of Dagestan and Caucasian brown – 71 and 74 days, respectively, as well as the breeding stock of the Bestuzhev breed – 86 days. The longest duration of the service period was recorded in the herds of gene pool farms of the Istoben breed and the Pechora type of the Kholmogory breed. The early age of retirement of Yakut cattle raises concerns, which, along with the small number of cows in this breed, will reduce not only the reproduction of the herd, but will also lead to the complete disappearance of this population. The lowest yield of calves per 100 cows is characterized by animals of the Pechora type of the Kholmogory breed – 63,1; for all other breeds it varies between 80–91 calves. Scientific novelty. For the first time, monitoring of the numbers and current state of industrial use of small breeds of dairy cattle in gene pool farms in Russia was carried out.

Digital technologies in dairy cattle breeding to improve the reproductive function of cows and heifers: A case study in Northern Kazakhstan

Background and Aim: In some countries, the application of digital technologies in dairy cattle breeding is still under development. This study aimed to investigate the use of digital technologies in dairy cattle breeding to improve the reproductive function of cows and heifers in three northern regions of Kazakhstan. Materials and Methods: This study explores the application of Austrian smaXtec bolus sensors, which enable the daily monitoring of the reproductive functions of cows and heifers in livestock. To control indicators of reproductive function in Simmental and Holstein-Friesian cattle breeds, a series of experiments were conducted before and after the introduction of boluses in the rumen. Results: It was established that the application of smaXtec boluses increases milk yield in 305 days, the percentage of conception in the first insemination and in cows with up to three inseminations, the duration of dry secretion, and the percentage of calve output per 100 heads. Moreover, the use of smaXtec boluses reduced the insemination index, duration of the calving-to-conception interval (open days), reproductive rate, and percentage of abortions and culls due to gynecological problems. Conclusion: The use of smaXtec boluses allows farmers and veterinarians to determine indicators, such as the period of sexual heat in livestock and diseases, in a timely manner and to increase the efficiency of feeding and controlling drinking cycles. Moreover, the application of smaXtec boluses minimizes labor costs associated with collecting data on indicators of reproductive function in cows and heifers and increases accuracy. Keywords: bolus, cows, digital technology, reproductive function, smaXtec.

345 Breed differences within heart scores of fattening feedlot cattle

Abstract Feedlot heart disease (FHD) is a condition in fattening beef cattle that arises from right-side heart remodeling resulting from alveolar hypoxia. This hypoxic environment is hypothesized to result from the large body mass of fattened cattle. Sensitive cattle have increased incidence of pulmonary hypertension resulting from compensation mechanisms of the individual. The severity of this remodeling is quantified at harvest by gross examination of the heart utilizing a visual grading system of 1-5, where a score of 1 is a normal heart and a score of 5 is a severely remodeled heart. Previously, heart score was found to contain sire differences and to be moderately heritable. This led to more questions regarding other potential factors influencing heart scores, one of which was breed differences. Therefore, the objective of this study was to examine the prevalence of heart remodeling in beef and dairy cattle breeds and to investigate whether some breeds had a greater prevalence of heart remodeling. Heart scores were collected on Angus-influenced animals raised in the panhandle of Texas (1,103 m) and a Beef x Dairy group raised in western Kansas (846 m). The total number of animal observations was 2,069. Twenty-four percent of the individuals exhibited moderate to severe remodeling (score 3 and greater). Of this cohort, 1,307 animals had breed composition data (i.e., Angus, Simmental, Jersey, and Holstein) suitable for use in the analysis. Breed proportions ranged from 0% to 100% for Angus, 0 to 93.25% for Simmental, 0% to 69.22% for Jersey, and 0% to 78.06% for Holstein. Utilizing a linear regression model with heart score as the response and breed percentages and heart scorers as fixed effects, the importance of breed composition (covariate) was determined. The percentages of Angus influence tended to be associated with heart score (P = 0.0506), with a regression coefficient of -0.005. The percentage of Simmental had an association with the variation in heart score (P < 0.05) and had a regression coefficient of -0.008. Additionally, the percentages of Jersey and Holstein were found to reduce the incidence of heart score by a factor of -0.014 and -0.018 (P < 0.05), respectively. In summary, an increased percentage of either Jersey or Holstein breed resulted in reduced heart scores, while the incidence of beef breeds was found to be associated with some to little difference in the improvement of heart scores, alluding to potential breed advantages in mitigating right sided heart remodeling.

202 Longitudinal comparative transcriptomics of dairy cattle at different altitudes reveals unique mechanisms underlying plateau hypoxia adaptation

Abstract The adaptation of livestock to high altitude hypoxic environment (plateau hypoxia adaptation) is important as they have a key role in the socio-economic conditions of the local residents. However, the underlying molecular mechanisms of plateau hypoxia adaptation of livestock are poorly understood. This study was objective to 1) construct the longitudinal transcriptional profiles of dairy cattle across five development stages; 2) reveal the transcriptomic changes of peripheral blood under different altitudes environment; and 3) identify key genes involved in plateau hypoxia adaptation in bovine. In this study, 109 peripheral blood samples from 70 Holstein cattle were performed whole transcriptome sequencing, including 56 at high altitude (> 3600 m) at five development stages (1, 2, 6, 12 and 18 mo) from 56 individuals, and 53 at low altitude (~1000 m) at three development stages (1, 2 and 6 mo) from 14 individuals. The peripheral transcriptional profile was obtained for high altitude cattle at five development stages, and for low altitude cattle for three development stages. By the transcriptome profile analysis in plateau cattle across five development stages, it was found that there were significant differences on mRNA transcriptome at different stages, and a noticeable shift occurred between 2 mo and 6 mo. By a comparative analysis of the transcription levels between high and low altitude cattle, 795, 900 and 880 differentially expressed genes (DEGs) were identified at the age of 1, 2 and 6 mo, respectively. The DEGs at three stages were enriched in several cellular communication, hypoxia response, and regulation of blood pressure, and immune-related signaling pathways. Furthermore, there were 64 DEGs shared across three comparative analyses at the three stages. By functional annotation analysis, we observed the shared DEGs of the three stages were enriched in the Notch signaling involved in heart development, regulation of phosphorylation, and positive regulation of MAP kinase activity. In summary, this study revealed the development-related transcriptomic shifts from birth to 18 mo of age in dairy cattle, and preliminarily elucidated the important signaling pathways involved in bovine plateau hypoxia adaptation by comparative analysis between high and low altitude cattle. The results of the current study will drive a better understanding of plateau hypoxia adaptation and can provide molecular targets for future breeding of plateau-adapted dairy cattle.

87 Estimation of genetic parameters for activity levels in North American Holstein cattle

Abstract High-producing dairy cows face various challenges during their productive life, including metabolic and infectious diseases, heat stress, and intensive management practices. Therefore, dairy cattle breeding programs have begun to focus on novel traits related to the overall resilience of the cows. Resilience has been defined as the ability of an animal to be minimally affected or to recover quickly from environmental disturbances while maintaining a certain level of productivity. In dairy cattle, resilience can be evaluated using measurements of longitudinal indicator traits, such as activity level, which are repeatedly measured throughout the lifetime of the animal. Variability in activity (defined in this study as average steps per hour and daily steps taken) might be a key indicator of resilience, due to activity of contemporary group animals deviating from normal behavior in less resilient cattle. Before resilience indicators are defined based on variability in certain longitudinal traits, there is a need for evaluating the genetic background of the source variable. Therefore, the primary objective of this study was to estimate variance components and genetic parameters of activity traits in lactating Holstein cows. The data was collected from a large dairy farm located in Indiana, using milking systems. Records from 6,332 Holstein cows for the traits of average activity per hour and number of daily steps were used in the analyses. The models used for the estimation of variance components included the significant (P < 0.05) fixed effects of contemporary group defined based on the concatenation of calving year and season, parity number (1, 2, 3+), pregnancy group (0 mo, 1-3 mo, 4-6 mo, and 7-9 mo), and days in milk (2-wkclasses), and the random effects of direct additive genetic, permanent environment, and residual effects. Genetic parameters were estimated for average activity per hour and daily steps for all parities together. Heritability estimates were calculated based on single-trait repeatability models and the (AI) REML method implemented in the BLUPF90+ software. Daily steps taken had a heritability (± SE) of 0.05 (± 0.02) and a repeatability of 0.29 (± 0.02). Activity per hour had a heritability estimate of 0.12 (± 0.04) and a repeatability of 0.57 (± 0.01). These results indicate that activity level is heritable in North American Holstein cattle and can be added to selection indexes if proven to be a key auxiliary trait for improving dairy cattle sustainability. As a next step, we will investigate the genetic relationship of activity traits with other relevant traits and derive resilience indicators based on variability in activity level.

Benchmarking claw health across three dairy cow breeds in 508 dairy farms using numerical claw health indicators

Currently, prevalence and incidence of claw lesions are used as parameters for benchmarking claw health. The aims of this study were to create a benchmarking system for claw health utilizing the claw health indicators Farm-Claw-Score (FCS) for the herd and Cow-Claw-Score (CCS) for the individual animal, and to benchmark claw health of the three predominant dairy cattle breeds in Austria. Claw health data from 17,642 cows from 508 Austrian dairy farms were analyzed. The CCS and FCS were calculated based on recorded claw lesions and their three severity levels using geometrically weighted scoring. The FCS of each of the dairy farms was classified into five percentile thresholds (P10, P25, P50, P75, P90), with the FCS calculated using the median value of CCS in each herd. Furthermore, claw health was benchmarked for three breeds (Fleckvieh, Holstein, Brown Swiss cows), using claw lesion prevalences and CCS values.When the median FCS was calculated, dairy farms in P50 and below had an FCS of 20.0, indicating very good claw health. However, P90 farms showed an FCS-MEDIAN of 67.5. Evaluation of the prevalences of the 14 claw lesions considered and the CCS values revealed that Fleckvieh cows (CCS-MEDIAN: 24.0), followed closely by Holstein cows (CCS-MEDIAN: 22.7) had significantly poorer claw health (P < 0.0001) compared to Brown Swiss cows (CCS-MEDIAN: 12.0). The use of CCS and FCS as primary claw health indicators allowed for a quick assessment of the current state of an individual cow and a dairy herd in a benchmarking system. Detailed information on the claw health of each animal and the dairy herd can be easily reviewed by examining diagnosis lists that display prevalences, particularly those related to lameness, in the respective electronic documentation systems.

Commercial perspectives: Genome editing as a breeding tool for health and well-being in dairy cattle

Genome editing is the latest breeding tool capable of accelerating the rate of genetic improvement for health and well-being traits in food animals. It enables the introduction of beneficial alleles within a single generation, including those of low frequency or absent in the population, while effectively bypassing linkage drag. For the dairy industry, genome editing can be used to make rapid genetic improvements that are precise, efficient, and transgene-free for functional traits that are not practically addressed without disrupting conventional breeding goals for overall economic merit based on genomic selection. Herein, various case studies for dairy cattle breeding are presented that demonstrate applications of genome editing for enhancing heat stress tolerance, reduced disease susceptibility, and/or other qualitative traits absent in some breeds. One case highlights the success of simultaneous editing of multiple loci through recent advancements in embryonic stem cell biology. Multiplexed editing is crucial for addressing the polygenic nature inherent to many economically important traits in livestock. However, maximizing the benefits of genome editing depends on the continued discovery of targets for editing that are commercially important. Commercialization also depends on rapidly evolving regulatory statutes for risk assessment, where some countries already permit the commercialization of cattle with non-GMO genome alterations through existing regulations. New breeding technologies like genome editing are now poised to have significant impact in equipping elite performance cattle to be more resilient to infectious disease and climate change without the loss of production gains obtained from decades of selection.

Heat stress effect on fertility of two imported dairy cattle breeds from different Algerian agro-ecological areas.

The present study investigates the susceptibility of two imported dairy cattle breeds to Algerian local climatic conditions, with a primary focus on heat stress (HS) and its repercussions on fertility traits. The dataset comprises 20,926 artificial insemination records involving 6,191 Prim'Holstein and 5,279 Montbéliarde cows. The animals originated from three distinct agro-ecological regions: littoral (L), semi-arid (SA), and arid (Ar), characterized by average annual Temperature-Humidity Index (THI) values of 75.2, 69.53, and 74.75, respectively. Logistic and linear regression models were performed to analyze the relationship between the THI on the AI day, season, and agro-ecological origin of the animals with the Conception Rate at 1st Artificial Insemination (CR 1stAI), Conception Risk (CR), Services per Conception (SPC), and reproductive period (RP). The results demonstrated a significant negative impact (P < 0.001) of THI > 72 compared to THI ≤ 72 on CR1st AI and CR for both cattle breeds (Prim'Holstein: -49.7% and - 17%, respectively; Montbéliarde: -20.7% and - 15%, respectively). Seasonal effects revealed a notably higher CR1stAI in winter and spring (≈ 25%) for Prim'Holstein and Montbéliarde cows compared to summer (19.41%) and autumn (19.12%), respectively. Furthermore, a reduced likelihood of conception at 1stAI and subsequent AI was observed during summer (0.839) and autumn (0.818) compared to winter for the Montbéliarde cows. Taking into account the littoral region as a reference, the likelihood of 1stAI success increased for both breeds in the SA region and decreased for the Ar region (P < 0.001). SPC increased for both breeds in THI > 72 categories (Prim'Holstein: 6.3%, Montbéliarde: 7.1%, P < 0.01), in the Ar region (Prim'Holstein: 30.9%, Montbéliarde: 26%, P < 0.001), and in the SA region (4%, P < 0.05) compared to the L region No significant seasonal effect on SPC was observed for either breed (P > 0.05). The RP increased in the THI > 72 category (Prim'Holstein: 4.1%, Montbéliarde: 7.4%, P < 0.001) and in the Ar region (Prim'Holstein: 122%, Montbéliarde: 73.4%) for both breeds. RP decreased in autumn compared to winter (Prim'Holstein: 15.3%, Montbéliarde: 8.4%). This study underscores the adverse impact of mild to severe heat stress (HS) and related factors (season, region) on fertility of Prim'Holstein and Montbéliarde cows under Algerian conditions, emphasizing the necessity for heat stress mitigation strategies, especially in adverse littoral humid and Saharan-arid environmental conditions.

ACADEMICIAN V. P. BURKAT (1939–2009) – FOUNDER OF MODERN THEORY AND METHODOLOGY OF BREEDING, ORGANIZER OF RESEARCH WORK IN ANIMAL HUSBANDRY IN UKRAINE (to the 85th anniversary of the birthday)

The purpose of the article is to reconstruct the major life milestones and creative path of the recognized scientist in the field of animal husbandry, Doctor of Agricultural Sciences, Professor, Academician of UAAS V. P. Burkat. Research methods are general scientific (analysis, synthesis, classification), special historical (problematic-chronological, comparative-historical), biographical and source studies. The contribution of the scientist to the development of theoretical and methodological principles of breeding, selection, and biotechnology of reproduction of farm animals is substantiated. The important role of V. P. Burkat in the organization of domestic research work in animal husbandry, in particular, in the formation of the Institute of Animal Breeding and Genetics named after M.V. Zubets NAAS was proven. The scientific heritage of the scientist is systematized, the priority of his research on the formation of a systematic concept of the breed, linear breeding, development of genetic and biotechnological bases of selection in animal husbandry, the actualization of the problem of conservation and rational use of the farm animals, etc. is substantiated. The contribution of V. P. Burkat to the formation of the modern theory and methodology of breeding in dairy and beef cattle breeding, the breeding of specialized breeds and types of cattle is revealed. It is shown that among his scientist's methodological developments, the most significant is the method of creating the Ukrainian Red-and-White Dairy breed, which is the basis for the development of other specialized domestic breeds of dairy and beef production directions. The program of activities and achievements of established by V.P. Burkat of the scientific school "Breeding and Biotechnology in Animal Husbandry" is summarized. The scholar's scientific search for the popularization and representation of the history of agricultural science in Ukraine is highlighted.