Holstein Dairy Cattle Research Articles

HUBUNGAN PERIODE LAKTASI, BCS DAN LINGKAR DADA DENGAN PRODUKSI SUSU SAPI PERAH FH (FRIESIAN HOLSTEIN) DI KPSP SETIAKAWAN KABUPATEN PASURUAN

The purpose of this research was to determine the relationship between lactation period, BCS and chest circumference with milk production of Friesian Holstein dairy cattle. The material used 36 dairy cattles period 3, 4, and 5. This research has conducted in farm KPSP Setia Kawan, Nongkojajar, Pasuruan on 20 July - 20 October 2022. The method used in this research was case study. The data collection technique in this study was purposive sampling. The variables observed were period lactation, BCS, chest circumference and milk production. Data obtained were analyzed by using correlation analysis, and simple linear regression analysis. The result showing that the linier regression equation between lactation period and milk production shows Y= 43.82 – 4.72X1 with a correlation coefficient negative is 0.65 and for the coefficient of determination is 42.3%, the meaning that for every increase 1 time of the lactation period, milk production will decrease 4.72 liters. The linier regression equation between BCS and milk production shows Y= 4.06 + 8.35X2 with a correlation coefficient positive is 0.70 and the coefficient of determination is 49.7%, the meaning is BCS that for every increase 1 score of the BCS, milk production will incrase 8.35 liters. The linier regression equation between chest circumference with milk production shows Y= (-17.57) + 0.22X3 with a correlation coefficient positive is 0.52 and the coefficient of determination is 27.3%, the meaning that for every increase 1 cm of the chest circumference, milk production will decrease 0.22 liters. It can be concluded that the more highly lactation period, milk production will decrease. Then the more highly score BCS and chest circumference, milk production will following high to.

Effect of Organophosphate Insecticides in Cattle Farming Feed on FSH and LH Hormone Levels in Dairy Cows in Kediri and Pujon

The issue plaguing the dairy cattle industry as a whole is low reproductive efficacy due to nutritional and reproductive disorders. To overcome this, nutrients in feed play a very important function. Feed is an essential component of any livestock operation. The requirements for animal protein depend on physiological status and production level. Ruminants can also reduce protein loss by recycling urea, a normally excreted byproduct of protein metabolism. Insecticides are components of pesticides used to kill insects. Organophosphate insecticides (OPs) are phosphate-containing insecticides. Phosphoric acid used to manufacture organophosphate insecticides. This insecticide is notorious for being the most toxic to mammals. This study seeks to determine the effect of feed-containing organophosphates on FSH and LH hormone concentrations in the blood of dairy cows. Mid-lactation For the purpose of this study, Friesian Holstein dairy cattle were divided into two experimental groups, group 1 (first ration) and group 2 (second ration). ANOVA analysis was used for statistical analysis.

Effect of olive cake supplementation on faecal microbiota profile of Holstein and Modicana dairy cattle

The present study aimed to investigate the effect of olive cake supplementation on faecal microbiota of Holstein (n = 16) and Modicana (n = 16) dairy cows. Although no difference in richness was detected, within breeds and between the two dietary treatment, the PERMANOVA analysis applied to the beta diversity allowed to discriminate samples according to breeds (p < 0.001) and treatment (p < 0.001). In Holstein cows, the olive cake supplementation led to the increase of Pseudobutyrivibrio and Christensenellaceae_R7-group genera (p < 0.05) recognized as health-promoting or associated with feed efficiency. Differently, no difference was detected between control and treated groups for Modicana suggesting a high adaptive capacity to diet changes. In addition, the higher prevalence of Firmicutes phyla in the Modicana microbiota reflected its better capacity to digest the fibrous sources. Our study supports the suitability of olive cake as a feed supplement for cows and could help validating a sustainable livestock system in the Mediterranean area, characterized by a relevant oil production and by a native breeds reared with extensive systems.

The marker effects of a single-step random regression model for 4 test-day traits in German Holsteins

The single-step genomic model has become the golden standard for routine evaluation in livestock species, such as Holstein dairy cattle. The single-step genomic model with direct estimation of marker effects has been proven to be efficient in accurately accounting for millions of genotype records. For diverse applications including frequent genomic evaluation updates on a weekly basis, estimates of the marker effects from the single-step evaluations play a central role in genomic prediction. In this study we focused on exploring the marker effect estimates from the single-step evaluation. Phenotypic, genotypic, and pedigree data were taken from the official evaluation for German dairy breeds in April 2021. A multilactation random regression test-day model was applied to more than 242 million test-day records separately for 4 traits: milk, fat, and protein yields, and somatic cell scores (SCS). Approximately one million genotyped Holstein animals were considered in the single-step genomic evaluations including ∼21 million animals in pedigree. Deregressed multiple across-country breeding values of Holstein bulls having daughters outside Germany were integrated into the national test-day data to increase the reliability of genomic breeding values. To assess the stability and bias of the marker effects of the single-step model, test-day records of the last 4 yr were deleted, and the integrated bulls born in the last 4 yr were truncated from the complete phenotypic dataset. Estimates of the marker effects were shown to be highly correlated, with correlations ∼0.9, between the full and truncated evaluations. Regression slope values of the marker-effect estimates from the full on the truncated evaluations were all close to their expected value, being ∼1.03. Calculated using random regression coefficients of the marker effect estimates, drastically different shapes of the genetic lactation curve were seen for 2 markers on chromosome 14 for the 4 test-day traits. The contribution of individual chromosomes to the total additive genetic variances seemed to follow the polygenic inheritance mode for protein yield and SCS. However, chromosome 14 was found to make an exceptionally large contribution to the total additive genetic variance for milk and fat yields because of markers near the major gene DGAT1. For the first lactation test-day traits, we obtained ∼0 correlations of chromosomal direct genomic values between any pair of the chromosomes; no spurious correlations were found in our analysis, thanks to the large reference population. For trait milk yield, chromosomal direct genomic values appeared to have a large variation in the between-lactation correlations among the chromosomes, especially between first and second or third lactations. The optimal features of the random regression test-day model and the single-step marker model allowed us to track the differences in the shapes of genetic lactation curves down to the individual markers. Furthermore, the single-step random regression test-day model enabled us to better understand the inheritance mode of the yield traits and SCS (e.g., variable chromosomal contributions to the total additive genetic variance and to the genetic correlations between lactations).

A randomized study on the effect of an extended voluntary waiting period in primiparous dairy cows on fertility, health, and culling during first and second lactation

When the voluntary waiting period (VWP), defined as the days between calving and when the cow is eligible to receive the first insemination, is extended, high-yielding dairy cows may have better opportunities to regain energy balance before first insemination. This study investigated the effect of an extended (145-215 days in milk [DIM], n = 280) or conventional (25-95 DIM, n = 251) VWP treatment on fertility, disease incidence, and culling rate in cows during their first lactation. The cows were also followed through a second lactation without intervention regarding VWP, during which the farmers could decide when they wished to start the inseminations. This was done in a randomized-controlled study on 16 high-yielding commercial herds in southern Sweden, containing a total of 531 primiparous cows of the Holstein and Red Dairy Cattle breeds. Data from the Swedish national dairy herd recording scheme collected between August 2018 and September 2021 were used in the analysis, including records on breed, calvings, estrus intensity, inseminations, disease, somatic cell count, culling date, and culling reason. During first lactation, more cows receiving the extended VWP treatment showed strong estrus intensity (score 4-5, 55% vs. 48%) and fewer showed moderate estrus intensity (score 3, 35% vs. 43%) at first insemination, compared with cows receiving the conventional VWP treatment. First service conception rate (FSCR) was higher (67% vs. 51%) and number of inseminations per conception (NINS) was lower (1.6 vs. 2.0) during the first lactation for cows receiving the extended compared with the conventional VWP treatment. For disease incidence rate or culling rate expressed as number of events per cow-time in the study, we found no differences between the cows receiving the 2 VWP treatments in any lactation. Calving to first service interval during second lactation was longer (86 vs. 74 d) for cows with extended compared with conventional VWP. In conclusion, primiparous cows with extended VWP showed improved reproductive functions, in the form of higher estrus intensity, greater FSCR, and lower NINS, during the first lactation. However, we observed no apparent effect on these fertility measures during the following lactation (without VWP intervention) and no differences in disease prevalence or culling between cows receiving the 2 different VWP treatments in either lactation. Compliance with the planned VWP treatment was lower for cows with planned extended compared with planned conventional VWP treatment. We studied the "intention-to-treat" effect (i.e., the results for all cows randomized to each treatment regardless of whether the planned VWP was achieved or not) to identify any bias arising due to degree of compliance. However, we found no difference in culling rate between cows randomized to an extended VWP compared with those randomized to a conventional VWP. These findings can be used to support management decisions on VWP length in high-yielding dairy herds.

Use of Danish National Somatic Cell Count Data to Assess the Need for Dry-Off Treatment in Holstein Dairy Cattle.

In Denmark, PCR testing of dairy cattle is commonly used to select animals for the antibacterial treatment of intramammary infection (IMI) during the dry-off period. IMI is associated with a high somatic cell count (SCC), routinely recorded for milk quality control for most commercial dairy herds. This study aimed to compare SCC curves over the lactation among dairy cows with positive vs. negative PCR test results for four major IMI pathogens. Data from 133,877 PCR-tested Holstein cows from 1364 Danish conventional dairy herds were used to fit a nonlinear mixed-effects model using a modified four-parameter Wilmink function. We stratified the data into first, second, third or fourth and later parity and fitted Wilmink curves to all SCC observations between 6 and 305 days in milk. The PCR tests were taken before dry-off at the end of the lactation to investigate which animals qualified for selective dry cow therapy. A PCR Ct-value of 37 and below was used to determine if an animal was PCR positive for any of the following IMI pathogens: Staphylococcus aureus, Streptococcus agalactiae, Str. dysgalactiae and Str. uberis. Our findings showed that mean SCC curve fits were higher for PCR-positive animals in all four parity groups and across lactations. The use of SCC data fitted to the entire lactation for multiple lactations enabled quantification of overall differences in SCC curves between cattle with and without detected IMI, adjusted for parity group and stage of lactation. These findings are relevant to the use of SCC to support treatment decisions.

Study of persistency of lactation and survival of Iranian Holstein dairy cattle using random regression model

The aim of this paper is to investigate whether characteristics of the first lactation (FL) curve of Iranian Holstein cows are associated with survival. Cows with least 10 test-days of milk production in their FL were used. The persistency of lactation (PL) and survival were estimated using a random regression model by restricted maximum likelihood with the ECHIDDNA software. We also used the Wood model to parameterize each individual lactation curve and then analyzed various curve characteristics using an animal model. The predicted breeding value (EBV) of the characteristics of the lactation curve of the cows from day 40 to 305 was predicted. The EBV of the production range (PR) and the slope of line in increasing phase ( m40,Peak) of production curve of sires with higher survival EBV were lower than other sires ( P &lt; 0.05). The estimates of PL were independent of survival estimate. Therefore, the PR from 40th day after calving can be considered as a definition of PL because the lower the PR, the flatter is the milk production curve. Genetic evaluation of young bulls for survival needs the data of death or culling of their daughters. Therefore, the bulls can genetically be evaluated for survival according to the PL and m40,Peak of FL information of their daughters.

Identification polymorphism of LHR and FSHR genes in Indonesian Holstein dairy cattle associated with productive and reproductive traits

Abstract. Setyorini YW, Kurnianto E, Sutopo, Sutiyono. 2023. Identification polymorphism of LHR and FSHR genes in Indonesian Holstein dairy cattle associated with productive and reproductive traits. Biodiversitas 24: 2898-2905. Luteinizing and follicle-stimulating hormones and their receptors play an important role in the reproductive system’s hormonal activity and physiological function. This study aimed to identify the genotype variation of the Luteinizing Hormone Receptor (LHR) gene exon 11 and the Follicle-stimulating Hormone Receptor (FSHR) gene exon 10 and to elucidate the associating between polymorphism with the milk and reproductive traits in dairy cattle. A total of 100 samples of deoxyribonucleic acid (DNA) from Indonesian Holstein dairy cattle were used in this study. Polymerase Chain Reaction Restriction Fragment Length Polymorphism (PCR-RFLP) was performed for genotyping of the Single Nucleotide Polymorphism (SNP) of the LHR and FSHR genes with the HhaI and AluI restriction enzymes, respectively. The collected phenotype data were milk production, quality, and reproductive trait. In addition, the general linear model procedure in the SAS program was carried out to investigate the association of genotypes with productive and reproductive traits. The results showed that the LHR gene in the population of this study was monomorphic, while the FSHR gene was polymorphic with three genotypes, namely CC, CG, and GG. The sequences of the FSHR gene indicated the presence of a mutation at nucleotide number 2037 that substitutes cytosine for guanine. Cows with the CC genotype showed better parameter service per conception (P&lt;0.05) than the other genotypes but did not correlate with other reproductive parameters and milk traits. Therefore, it was concluded that SNP g.2037C&gt;G polymorphism at FSHR gene exon 10 was identified in the Indonesian Holstein Dairy cattle population and associated with service per conception parameters but not with milk trait.

Temperature-Humidity Index Values and Their Significance on the Daily Production of Dairy Cattle in the North African Arid Region

Climate changes affect the economic viability of livestock. Therefore, this study aimed to characterize the heat stress in Holstein cattle raised in the arid region of Tunisia as well as to evaluate the effect of the temperature-humidity index (THI) on daily milk production and components. For this reason, 76940 monthly individual records collected from 1995 to 2018 from 3056 Holstein cows were used. THI calculated from ambient temperature and relative humidity was used as a measure of heat stress. To study the effect of THI on milk production, a repeated measures linear mixed model was used. Results showed a significant (P<0.01) decrease in daily milk yield, daily protein, and fat content in all cow’s parity classes. For each point increase of the THI values beyond 64, milk yield, fat, and protein contains decreased by 0.32 kg, 0.09, and 0.06 %, respectively. Moreover, when the THI value varied from 64 to 85, fat content decreased by 29 %, protein by 17 %, and milk production by 30 %. Heat stress impact negatively milk production and milk components of dairy cows. These results can be a way to improve the length of productive life for Holstein dairy cattle in the hard climate. Serious management strategies are needed to improve dairy cow productivity and minimize the heat stress impact.

Slaughter indicators of purebred Hereford bulls depending on the genotypes of the gene GDP-l-fucosynthetase (TSTA3)

The paper presents the results of studying the associated effect of complex genotypes for the genes diacylglycerol O-acyl transferase 1 (DGAT1), somatotropin (GH), prolactin (PRL) and beta-lactoglobulin (BLG) on the milk productivity of Holstein dairy cattle of domestic selection. The object of research was cattle and biological material (ear pluck) from cows of Holstein dairy cattle of domestic selection, contained in the agricultural production cooperative named after I.P. Senko, Grodno region. DNA genotyping of animals for the genes of diacylglycerol O-acyl transferase 1 (DGAT1), somatotropin (GH), prolactin (PRL), and beta-lactoglobulin (BLG) was performed using the polymerase chain reaction (PCR) method and restriction fragment length polymorphism ( RFLP). The results of studies on the assessment of the associated effect of complex genotypes for the genes diacylglycerol O-acyl transferase 1 (DGAT1), somatotropin (GH), prolactin (PRL) and beta-lactoglobulin (BLG) on the milk productivity of Holstein cows of dairy cattle domestic selection showed that in terms of the mass fraction of fat and the amount of milk fat in milk, in most cases, the highest rates were in animals with the complex genotype.

Association of the complex of polymorphic variants of the DGAT1, GH, PRL and BLG, genes with dairy productivity indicators of holstein dairy cattle cows of domestic selection

The paper presents the results of studying the associated effect of complex genotypes for the genes diacylglycerol O-acyl transferase 1 (DGAT1), somatotropin (GH), prolactin (PRL) and beta-lactoglobulin (BLG) on the milk productivity of Holstein dairy cattle of domestic selection. The object of research was cattle and biological material (ear pluck) from cows of Holstein dairy cattle of domestic selection, contained in the agricultural production cooperative named after I.P. Senko, Grodno region. DNA genotyping of animals for the genes of diacylglycerol O-acyl transferase 1 (DGAT1), somatotropin (GH), prolactin (PRL), and beta-lactoglobulin (BLG) was performed using the polymerase chain reaction (PCR) method and restriction fragment length polymorphism ( RFLP). The results of studies on the assessment of the associated effect of complex genotypes for the genes diacylglycerol O-acyl transferase 1 (DGAT1), somatotropin (GH), prolactin (PRL) and beta-lactoglobulin (BLG) on the milk productivity of Holstein cows of dairy cattle domestic selection showed that in terms of the mass fraction of fat and the amount of milk fat in milk, in most cases, the highest rates were in animals with the complex genotype DGAT1ККGHLLPRLAABLGAB.

Single nucleotide polymorphisms in β-Lactoglobulin, k-casein and DGAT1 genes as candidates for rigorous selection of milk composition and performance traits in Holstein cattle

The aim of this study was to investigate β-Lactoglobulin, k-casein and DGAT1 gene polymorphism and to associate this polymorphism with milk composition and performance traits in Holstein cattle using the PCR-DNA sequencing approach. On the basis of farm records, accurate phenotypic data for milk composition and performance traits were obtained for seventy Holstein dairy cows. Blood samples were collected from each animal into tubes containing disodium EDTA as an anticoagulant for DNA extraction. PCR was carried out for amplification of fragments of exon 4 (301-bp) of β-Lactoglobulin, exon 4 (373-bp) of k-casein, and exon 7 (321-bp) of DGAT1 genes. DNA sequencing assessment elaborated single nucleotide polymorphisms (SNPs) in the investigated genes amongst the enrolled dairy cows. On the basis of the dairy cows that harbored identified SNPs in each gene, the animals were allocated into different groups. The least square means of the groups revealed a significant association (P ≤ 0.05) between SNPs and milk production and performance traits. Logistic regression model confirmed a highly significant effect of the identified SNPs on the studied traits, where a moderate to strong relationship was detected between the predictor (SNPs) and the grouping variable (Milk composition and performance traits). Consequently, the identified SNPs in β-Lactoglobulin, k-casein and DGAT1 genes could be used as candidates for developing marker assisted selection (MAS) for milk composition and performance traits in Holstein dairy cattle.

Effects of udder edema on parlor behavior in first- and second-lactation Holstein dairy cows

Udder edema (UE) is a metabolic disorder that most commonly occurs around the transition period. However, there are gaps in our knowledge about its effects on parlor behavior. The aim of this study was to examine the prevalence and effects UE has on behavior in the milking parlor during udder preparation and active milking from 2 to 9 DIM in first (FL) and second lactation (SL) Holstein dairy cattle. Each cow (n = 375) was observed once and monitored from the point of first contact during udder preparation through the first 5 min of active milking. Behavior measurements include step, kick, and kicking off the milking unit (KOU). Cows were determined to have UE when the rear udder medial suspensory ligament lost definition and was softened due to the presence of interstitial fluid. In this study, 237/247 (95.6%) FL cows and 104/128 (81.3%) SL cows presented with UE. First lactation cows with UE had a higher step rate (3.97 steps/session) when in contact during udder preparation and attachment (2.80 steps/session), and kick rate during milking (2.68 kicks/milking session) when compared with SL cows with UE (2.37 steps/session, 1.25 steps/session, 1.24 kicks/milking session). FL cows with UE had a lower step rate during milking (6.04 steps/milking session) compared with FL cows without UE (7.20 steps/milking session). FL cows with UE had a higher average KOU count (μ = 0.220 kick-offs) than SL cows with UE (μ = 0.029 kick-offs) and FL cows without UE (μ = 0.091 kick-offs). The results indicate that UE is prevalent among dairy cattle, and the disorder has effects on behaviors presented in the milking parlor. Reducing UE has the potential to decrease step and kick behavior to improve welfare of transition cows and reduce risk to dairy caretakers in the milking parlor.

MILK PRODUCTION AND BUSINESS ANALYSIS ON DAIRY CATTLE AFFECTED BY PMK IN “KAMPOENG TERNAK” SIDOARJO LIVESTOCK: A LITERATURE REVIEW

mineral superboosters and concentrating immunoboosters in the feed. This research was conducted on the smallholder dairy cattle in "Kampoeng Ternak," Taman District, Sidoarjo, for 42 days. The material used was 18 Friesian Holstein (FH) dairy cattle suffering from FMD and decreased milk production. This research was carried out experimentally with three treatments: P0 (treatment injected multivitamins 10 ml + antibiotic long-acting 20 ml), P1 (treatment injected multivitamins 10 ml + antibiotic long-acting 20 ml and mineral super booster 40 grams), and P2 (10 ml treatment injected multivitamins + 20 ml long-acting antibiotics, adding 40-gram mineral super booster and 800-gram concentrate immunobooster). The data collected in this study is feed consumption, milk production, and profit analysis of business in the farm. The data were calculated and analyzed using anova. This literature review aims to describe adding mineral supplements to FH dairy cattle suffering from foot and mouth disease (FMD) as an alternative because it can increase milk production.

The Relationship Between Lactation Period and Colostrum Age With Colostrum Protein Content of Friesian Holstein (FH) Dairy Cattle in KPSP Setia Kawan, Pasuruan District

Colostrum is the secretion of the udder glands after the cow gives birth and is given to the calf for 3-5 days. The purpose of this study was to determine the relationship between the lactation period and colostrum age on the colostrum protein content of FH dairy cows. This research was conducted at KPSP Setia Kawan, Pasuruan. The research was conducted in August-November 2022. The research materials were FH dairy cows with lactation periods 1,2,3, and cow colostrum which were analyzed with the Lactoscan Milk Analyzer. The research method uses case study method and purposive sampling. Research using simple linear regression analysis and correlation. The results of the regression equation study the relationship between the lactation period and colostrum protein content, namely Y =5.22+0.46X with a correlation value (r)=0.158 and a coefficient of determination (R2)=0.025. The results of the regression equation for the relationship between colostrum age and colosrum protein content are Y=10.79-1.55X with a correlation value (r)=0.88 and a coefficient of determination (R2)=0.77. The conclusion of the study is that there is a positive relationship between the lactation period and colostrum protein and there is a negative relationship between colostrum age and colostrum protein. Keywords : FH dairy cattle, colostrum, lactation period, colostrum protein.

Genetic Analysis of Methane Emission Traits in Holstein Dairy Cattle.

Genetic selection can be a feasible method to help mitigate enteric methane emissions from dairy cattle, as methane emission-related traits are heritable and genetic gains are persistent and cumulative over time. The objective of this study was to estimate heritability of methane emission phenotypes and the genetic and phenotypic correlations between them in Holstein cattle. We used 1765 individual records of methane emission obtained from 330 Holstein cattle from two Canadian herds. Methane emissions were measured using the GreenFeed system, and three methane traits were analyzed: the amount of daily methane produced (g/d), methane yield (g methane/kg dry matter intake), and methane intensity (g methane/kg milk). Genetic parameters were estimated using univariate and bivariate repeatability animal models. Heritability estimates (±SE) of 0.16 (±0.10), 0.27 (±0.12), and 0.21 (±0.14) were obtained for daily methane production, methane yield, and methane intensity, respectively. A high genetic correlation (rg = 0.94 ± 0.23) between daily methane production and methane intensity indicates that selecting for daily methane production would result in lower methane per unit of milk produced. This study provides preliminary estimates of genetic parameters for methane emission traits, suggesting that there is potential to mitigate methane emission in Holstein cattle through genetic selection.

The effects of ration particle size and live yeast supplementation on dairy cows performance under heat stress conditions

The objectives of this experiment were to evaluate the effects of ration particle size and dietary supplementation of live yeast (LY; Saccharomyces cerevisiae) on dry matter intake, milk yield and milk quality, apparent nutrient digestibility, ruminal fermentation parameters, and ruminal volatile fatty acids in dairy cattle under heat stress condition. Four multiparous Holstein dairy cattle in midlactation were fed 4 diets: high particle size (HPS), high particle size with 1g/d/cow LY (Levucell® Sc 10 ME Titan® CNCM I-1077 (10 × 109cfu/g) (HPS + LY), short particle size (SPS), short particle size with 1g/d/cow LY (Levucell® Sc 10 ME Titan® CNCM I-1077 (10 × 109cfu/g) (SPS + LY). Treatments were arranged in a 2 × 2 factorial within a 4 × 4 Latin square design. Decreasing ration particle size increased intakes of dry matter (DM), neutral detergent fiber (NDF) (P < 0.05) but decreased peNDF intake (P < 0.0001). Milk production and milk fat percentage were similar in cows. Cows fed SPS had lower milk protein percentage (P < 0.05). No treatments had any significant effect on apparent nutrient digestibility. Ruminal pH was higher in cows supplemented LY (P < 0.05). The ruminal total volatile fatty acid (VFA) concentration and percentage of VFAs were not significantly affected by ration particle size or dietary LY supplementing. Rectal temperature (oC) and respiratory rate (breaths/min) were similar between the groups. In conclusion, it may be concluded that decreasing ration particle size increased DM, and NDF intakes, without affecting milk yield or feed efficiency in cows exposed moderate heat stress.

Pedigree and genome-based patterns of homozygosity in the South African Ayrshire, Holstein, and Jersey breeds.

The erosion of genetic diversity limits long-term genetic gain and impedes the sustainability of livestock production. In the South African (SA) dairy industry, the major commercial dairy breeds have been applying estimated breeding values (EBVs) and/or have been participating in Multiple Across Country Evaluations (MACE). The transition to genomic estimated breeding values (GEBVs) in selection strategies requires monitoring of the genetic diversity and inbreeding of current genotyped animals, especially considering the comparatively small population sizes of global dairy breeds in SA. This study aimed to perform a homozygosity-based evaluation of the SA Ayrshire (AYR), Holstein (HST), and Jersey (JER) dairy cattle breeds. Three sources of information, namely 1) single nucleotide polymorphism (SNP) genotypes (3,199 animals genotyped for 35,572 SNPs) 2) pedigree records (7,885 AYR; 28,391 HST; 18,755 JER), and 3) identified runs of homozygosity (ROH) segments were used to quantify inbreeding related parameters. The lowest pedigree completeness was for the HST population reducing from a value of 0.990 to 0.186 for generation depths of one to six. Across all breeds, 46.7% of the detected ROH were between 4 megabase pairs (Mb) and 8Mb in length. Two conserved homozygous haplotypes were identified in more than 70% of the JER population on Bos taurus autosome (BTA) 7. The JER breed displayed the highest level of inbreeding across all inbreeding coefficients. The mean (± standard deviation) pedigree-based inbreeding coefficient (FPED) ranged from 0.051 (±0.020) for AYR to 0.062 (±0.027) for JER, whereas SNP-based inbreeding coefficients (FSNP) ranged from 0.020 (HST) to 0.190 (JER) and ROH-based inbreeding coefficients, considering all ROH segment coverage (FROH), ranged from 0.053 (AYR) to 0.085 (JER). Within-breed Spearman correlations between pedigree-based and genome-based estimates ranged from weak (AYR: 0.132 between FPED and FROH calculated for ROH <4Mb in size) to moderate (HST: 0.584 between FPED and FSNP). Correlations strengthened between FPED and FROH as the ROH length category was considered lengthened, suggesting a dependency on breed-specific pedigree depth. The genomic homozygosity-based parameters studied proved useful in investigating the current inbreeding status of reference populations genotyped to implement genomic selection in the three most prominent South African dairy cattle breeds.

Eradication of carriers of Complex Vertebral Malformation (CVM) and Brachyspina in Polish Holstein-Friesian bulls.

CVM ( Complex Vertebral Malformations) and Brachyspina (BY) are the most common autosomal recessive genetic defects occurring in the last two decades in Holstein dairy cattle around the world. Beginning from 2004 and 2014, 3035 and 338 Polish Holstein-Friesian bulls were tested to find carriers of CVM and BY, respectively. Among analyzed bulls 191 CVM carriers (6.29%) and 20 BY carriers (5.92%) were identified. No CVM carriers were observed beginning from 2016, whereas only single BY carriers was identified annually for the last 5 years. One bull turned to be double CVM/ BY carrier as a son of also double CVM/BY top Dutch sire (JABOT 90676-4-9). It is shown that CVM and BY defects are practically eradicated from Polish dairy cattle although incidental testing should be continued if new bulls with CVM or BY carriers in sire or dam pedigree will unexpectedly appear.

A Study on Changes in Udder Traits of Korean Holstein Dairy Cattle according to Various Environmental Factors

A Study on Changes in Udder Traits of Korean Holstein Dairy Cattle according to Various Environmental Factors