Holstein-Friesian Breed Research Articles

Comparative reproductive performance evaluation of Holstein Friesian cattle breeds in two different agro ecological conditions, Oromia region, Ethiopia

SummaryComparative study was conducted at Alage and Ardaita Agricultural Technical and Vocational Education Training College dairy farm to evaluate the reproductive performance of Holstein Friesian (HF) and associated factors in the two farms. The data collected from 2000 to 2015 on reproductive traits (n= 1688) were analyzed using general linear model procedures of SAS version 9.2 (SAS, 2008). The result revealed that an overall least square means and standard errors for Age at first Service (AFS), Age at first calving (AFC), Calving interval (CI), Days open (DO) and Number of services per conception were 29.70 ± 0.49 months, 39.75 ± 0.53 months, 465.76 ± 7.22 days, 188.11 ± 7.22 days and 1.31 ± 0.04, respectively. AFC was significantly influenced by agro ecology (P< 0.001) and year of birth (P< 0.01). Besides this, agro ecology (P< 0.001) and year of birth (P< 0.05) was significantly influenced by AFC. Year of calving and parity had significant effect (P< 0.001) on CI and DO. Except CI, agro ecology had significant effect on all traits. Service per conception was significantly influenced by agro ecology (P< 0.05) and year of calving (P< 0.01). Season of birth and season of calving was not significant on all reproductive traits. Except SPC, the result obtained for AFS, AFC, CI and DO were below the standard expected from commercial dairy farm. Poor efficiency of estrus detection and expression were the most probable management factors accounted for longer period of AFS, AFC, CI and DO. Improving the level of nutrition as well as efficiency of estrus detection system is required for optimal reproduction performance of HF breed in the area.

Sperm mitochondrial membrane potential and motility pattern in the Holstein bull semen positive for heparin binding proteins

Present study was aimed to evaluate sperm motility and mitochondrial membrane potential (MMP) in relation to the presence of heparin binding proteins (HBPs) in semen. Semen was collected from 17 Holstein Friesian breeding bulls. Seminal plasma and sperm membrane proteins were isolated by precipitation method; HBPs were isolated using heparin-sepharose affinity chromatography. SDS-PAGE was performed and bulls were categorized into 3 groups based on presence/absence of 24 and 30 kDa HBPs. Computer-assisted semen analysis revealed that fresh ejaculates of bulls positive for 30 kDa HBP had 4.24 and 14.18% of higher total motile sperm than semen with 24 kDa and negative for HBPs. Semen with 30 and 24 kDa had 18.72 and 12.34% of higher number of sperm with progressive motility and velocity than semen devoid of HBPs. Simultaneous assessment of plasma membrane integrity (PMI) and MMP by fluorescence staining revealed that post-thaw sperm of semen with 30 kDa HBP had 6.28 and 12.79% of higher intact PMI. Further, sperm of semen with 30 kDa HBP had 4.61 and 10.50% of higher MMP, which had travelled an extra distance of 9.71 and 4.95 mm through cervical mucus than semen with 24 kDa and devoid of HBPs. The mucus penetration distance showed a strong positive correlation with high MMP, PMI, sperm motility and velocity. It is to be concluded that HBPs were able to sustain higher percentage of motile sperm with progressive motility and MMP which was depicted by more mucus penetration distance.

The presence of heparin binding proteins and their impact on semen quality of Holstein Friesian bulls

Present study was designed to evaluate the semen quality of breeding bulls positive for 24 and 30 kDa heparin binding proteins (HBPs) in the semen. Seventeen Holstein Friesian breeding bulls were screened for 24 and 30 kDa HBPs in semen by heparin-sepharose affinity chromatography and SDS-PAGE, and grouped into three based on presence/absence of HBPs. In vitro characteristics of spermatozoa were assessed by standard analysis of sperm abnormalities, functional membrane integrity, acrosome integrity and sperm chromatin integrity in fresh and frozen- thawed semen. Bulls positive for 30 kDa had lowest sperm abnormalities and sperm chromatin fragmentation than bulls positive for 24 kDa and without HBPs in the fresh ejaculates. Further, fresh semen positive for 30 kDa had 8.76% of higher active plasma membrane with 7.63% intact acrosome. The process of cryopreservation of semen increased sperm abnormalities, acrosome damage and chromatin fragmentation in all the semen samples irrespective of presence/absence of HBPs. However, semen samples positive for 24 and 30 kDa HBPs were able to sustain lower percentage of post-thaw sperm abnormalities with higher chromatin integrity in comparison to semen devoid of HBPs. Moreover, semen with 24 and 30 kDa HBPs had higher post-thaw intact acrosome with active plasma membrane than negative semen. The results concluded that bulls positive for 30 kDa had 12.43 and 28.37 percentages of better semen quality than bulls with 24 kDa and devoid of HBPs.

Serum paraoxonase 1 (PON1) activity and lipid metabolism parameters changes in different production cycle periods of Holstein-Friesian, Polish Red and Norwegian breeds.

We investigated the measurement of paraoxonase 1 (PON1), as a potential marker of redox state changes in dairy cows, its involvement in lipid metabolism and compared it with superoxide dismutase (SOD) activity changes. We also evaluated lipid metabolism parameters associated with dairy production. PON1 paraoxonase and arylesterase acitvities, SOD activity, beta-hydroxybutyrate (BHB), uric acid (UA), high density lipoprotein (HDL), low density lipoprotein (LDL), cholesterol and triglyceride concentrations were measured in Holstein-Friesian, Polish Red and Norwegian breeds serum in two production cycles. Our data showed a significant postpartum depletion in PON1 activity and lipoprotein and lipid products concentrations, with elevated BHB values. However, there were no significant changes in SOD activity and uric acid concentrations in Holstein-Friesian and Polish Red breeds after calving. At lactation peak there was a significant SOD activity decrease correlated with standardized PON1 activity depletion in all examined breeds. The results suggest that PON1 might be a better parameter for minimal redox state changes in serum, shortly after labour in the examined breeds.

Prediction of individual milk proteins including free amino acids in bovine milk using mid-infrared spectroscopy and their correlations with milk processing characteristics

The aim of this study was to evaluate the effectiveness of mid-infrared spectroscopy in predicting milk protein and free amino acid (FAA) composition in bovine milk. Milk samples were collected from 7 Irish research herds and represented cows from a range of breeds, parities, and stages of lactation. Mid-infrared spectral data in the range of 900 to 5,000cm−1 were available for 730milk samples; gold standard methods were used to quantify individual protein fractions and FAA of these samples with a view to predicting these gold standard protein fractions and FAA levels with available mid-infrared spectroscopy data. Separate prediction equations were developed for each trait using partial least squares regression; accuracy of prediction was assessed using both cross validation on a calibration data set (n=400 to 591 samples) and external validation on an independent data set (n=143 to 294 samples). The accuracy of prediction in external validation was the same irrespective of whether undertaken on the entire external validation data set or just within the Holstein-Friesian breed. The strongest coefficient of correlation obtained for protein fractions in external validation was 0.74, 0.69, and 0.67 for total casein, total β-lactoglobulin, and β-casein, respectively. Total proteins (i.e., total casein, total whey, and total lactoglobulin) were predicted with greater accuracy then their respective component traits; prediction accuracy using the infrared spectrum was superior to prediction using just milk protein concentration. Weak to moderate prediction accuracies were observed for FAA. The greatest coefficient of correlation in both cross validation and external validation was for Gly (0.75), indicating a moderate accuracy of prediction. Overall, the FAA prediction models overpredicted the gold standard values. Near-unity correlations existed between total casein and β-casein irrespective of whether the traits were based on the gold standard (0.92) or mid-infrared spectroscopy predictions (0.95). Weaker correlations among FAA were observed than the correlations among the protein fractions. Pearson correlations between gold standard protein fractions and the milk processing characteristics of rennet coagulation time, curd firming time, curd firmness, heat coagulating time, pH, and casein micelle size were weak to moderate and ranged from −0.48 (protein and pH) to 0.50 (total casein and a30). Pearson correlations between gold standard FAA and these milk processing characteristics were also weak to moderate and ranged from −0.60 (Val and pH) to 0.49 (Val and K20). Results from this study indicate that mid-infrared spectroscopy has the potential to predict protein fractions and some FAA in milk at a population level.

Lactoferrin and Immunoglobulin G Concentration in Bovine Milk from Cows with Subclinical Mastitis during the Late Lactation Period

Background: Lactoferrin and immunoglobulin G in milk have an important role in udder resistance to infection in the involution period. Both proteins express antimicrobial activity- lactoferrin by the binding and sequestration of iron ion; and immunoglobulin G by complement activation, bacterial opsonization and agglutination. Many factors affect lactoferrin and immunoglobulin G concentrations in bovine milk, such as the stage of lactation, milk production, and intramammary infections. The aim of this study was to determine concentrations of lactoferrin and immunoglobulin G in milk from healthy cows and subclinical mastitic cows during the late lactation period, and to evaluate the relationship between them.Materials, Methods & Results: A total of 150 quarter milk samples from 41 cows (Holstein-Friesian breed) in late lactation period were reviewed in this study. Milk samples were collected during morning milking, using aseptic techniques in sterile test tubes. From each sample, 0.1 mL of milk was plated on Columbia blood agar base with 5% defibrinated ovine blood, MacConkey agar and Sabouraud dextrose agar and incubated for 24 h - 48 h (bacteria) and 5 days (yeasts, mould) at 37oC. Milk samples for detection lactoferrin and immunoglobulin G concentration were skimmed at 1,400 g for 45 min and stored at -20°C until analysis. Lactoferrin concentration in bovine milk was determined using the Bovine Lactoferrin ELISA Quantitation Set. Milk samples were diluted at a ratio of 1:10,000. Plates were read at 450 nm absorbence values. Immunoglobulin G concentration was determined by the immunodiffusion method using radial immunodiffusion (RID) plates. Milk samples were diluted in a ratio of 1:30. Reading of results was done after incubation for 48 h by measuring the diameter of the precipitation ring. The highest mean lactoferrin concentration was observed in udder quarters infected with contagious pathogens (Streptococcus agalactiae and Staphylococcus aureus), while the highest mean immunoglobulin G concentration was detected in milk samples where minor mastitis pathogens (coagulase-negative staphylococci and Corynebacterium spp.) were isolated. Milk samples where Staphylococcus aureus was isolated had the lowest immunoglobulin G concentration, and the lowest lactoferrin concentration was observed in samples infected with enviromental pathogens (Streptococcus dysgalactiae).Discussion: This study showed that lactoferrin and immunoglobulin G concentrations are higher in milk samples from subclinical mastitic cows than in milk from normal lactating cows. Lactoferrin concentrations in milk samples from udder quarters infected with major mastitis pathogens were significantly higher than in milk infected with minor mastitis pathogens. The lowest concentration of immunoglobulin G was detected in milk samples where Staphylococcus aureus was isolated, while the highest immunoglobulin G concentration was observed in milk samples from quarters infected with minor mastitis pathogens. Lactoferrin and immunoglobulin G concentrations were significantly and positively correlated in all milk samples. This means that cows with high lactoferrin concentrations have high immunoglobulin G concentrations. In quarter milk samples infected with Staphylococcus aureus, lactoferrin and immunoglobulin G concentrations were negatively correlated. The cause of these findings could be the suppression of local immune response of mammary gland.

Hematological Parameters in Cows in Early Lactation Treated with Ketoprofen and their Relationship with Lipid Mobilization and Ketogenesis

Background: Dairy cows are exposed to numerous hematological and biochemical changes, what is bringing cows into the state of increased metabolic activity and physiological adaptations. These adaptive processes have resulted in increased lipid mobilization and ketogenesis with increased concentration of non-esterified fatty acids (NEFA) and beta-hydroxybutyrate (BHB). As a non steroidal anti-inflammatory drug, ketoprofen produces anti-inflammatory effects. The main objective of the present study was to found relationship between hematological parameters and ketoprofen administration and high lipid mobilization and ketogenesis in cows treated with ketoprofen immediately after calving.Materials, Methods & Results: Ketoprofen was used (3 mg/kg body weight) intramuscularly for three consecutive days post-partum on 15 cows of Holstein-Friesian breed. Cows of the control group (n = 15) were not treated with ketoprofen. Blood samples were collected at the day of calving, in the first and in the second week after parturition from the coccygeal vein of the both groups. Hematological parameters (erythrocytes, hemoglobin, neutrophils, lymphocytes and mean platelet volume) were determined on the automatic hematological counter. Metabolic parameters (NEFA, BHB) were determined by standard colorimetric kits using a semi-automatic biochemistry analyzer. Student’s t-test was used to determine the influence of the application of ketoprofen to the hematological parameters. The data analysis was performed using SPSS, version 19.0, software package for Microsoft Windows (IBM, Armonk, NY, USA). The results of comparison with (P < 0.05) were considered to represent statistically significant differences. Difference in correlation test between NEFA and BHB and other blood parameters in experimental and control group of cows were determined by the Fischer r-to-z transformation. The research results show that there was a increased red blood cell count and a higher concentration of hemoglobin (P < 0.05), fewer neutrophils (P < 0.01), lower number of lymphocytes (P < 0.01) and fewer mean platelet volume in cows that received ketoprofen after calving than those of the control. Determined hematological parameters and values of NEFA and BHB are in correlation. The correlation coefficients were significantly lower in the experimental group of cows. The intensity of the connection between hematological parameters and value of NEFA and BHB decreases.Discussion: It is well known that dairy cows with excessive adiposity manifest a low-grade inflammation and that elevated NEFA concentrations present positive risk factors for many proinflammatory diseases. Analyzing the results in this examination, it has been noticed that the increase of NEFA and BHB after calving were significantly lower in group of cows treated with ketoprofen. Also, determined hematological parameters and values of NEFA and BHB are in correlation. The intensity of these connection decreases in ketoprofen treated cows. In current study, in cows treated with ketoprofen there is decrease in concentrations of inflammatory mediators such as neutrophils and lymphocytes. Red blood cell and hemoglobin concentration decreased in the peripartal period as a result of inflammation. In cows treated with ketoprofen these concentrations increased. In many inflammatory conditions mean platelets volume is increased while there is a decrease in ketoprofen treated cows. Presented results indicate strong relationship between the concentration of NEFA, as well as BHB and hematological parameters indicating that the dependence of hematological parameters of intensity of lipid mobilization and ketogenesis was significantly lower in cows treated with ketoprofen immediately after calving.

Evidence for placental compensation in cattle

Prenatal development is known to be extremely sensitive to maternal and environmental challenges. In this study, we hypothesize that body growth and lactation during gestation in cattle reduce nutrient availability for the pregnant uterus, with consequences for placental development. Fetal membranes of 16 growing heifers and 27 fully grown cows of the Belgian Blue (BB) breed were compared to determine the effect of body growth on placental development. Furthermore, the fetal membranes of 49 lactating Holstein Friesian (HF) cows and 27 HF heifers were compared to study the impact of dam lactation compared to dam body growth. After parturition, calf birth weight and body measurements of dam and calf were recorded, as well as weight of total fetal membranes, cotyledons and intercotyledonary membranes. All cotyledons were individually measured to calculate both the surface of each individual cotyledon and the total cotyledonary surface per placenta. Total cotyledonary surface was unaffected by breed or the breed×parity interaction. Besides a 0.3 kg lower cotyledonary weight (P=0.007), heifer placentas had a smaller total cotyledonary surface compared with placentas of cows (0.48±0.017 v. 0.54±0.014 m2, respectively, P<0.001). Within the BB breed, fetal membranes of heifers had a 1.5 kg lower total weight and 1.0 kg lower intercotyledonary membrane weight (P<0.005) compared with cows. A cotyledon number of only 91±5.4 was found in multiparous BB dams, while growing BB heifers had a higher cotyledon number (126±6.7, P<0.001), but a greater proportion of smaller cotyledons (<40 cm2). Within the HF breed, no parity effect on intercotyledonary membrane weight, cotyledon number and individual cotyledonary surface was found. Placental efficiency (calf weight/total cotyledonary surface) was similar in HF and BB heifers but significantly higher in multiparous BB compared with multiparous HF dams (106.0±20.45 v. 74.3±12.27 kg/m2, respectively, P<0.001). Furthermore, a seasonal effect on placental development was found, with winter and spring placentas having smaller cotyledons than summer and fall placentas (P<0.001). Main findings of the present study are that lactation and maternal growth during gestation entail a comparable nutrient diverting constraint, which might alter placental development. However, results suggest that the placenta is able to manage this situation through two potential compensation mechanisms. In early pregnancy the placenta might cope by establishing a higher number of cotyledons, while in late gestation a compensatory expansion of the cotyledonary surface is suggested to meet the nutrient demand of the fetus.

Estimation of nonadditive genetic influences on standard lactation production (305 days) in upgrading of Serbian-Fleckvieh to Holstein-Friesian cattle breed

Estimation of nonadditive genetic influences on standard lactation production (305 days) in upgrading of Serbian-Fleckvieh to Holstein-Friesian cattle breed

Prevalence and antimicrobial susceptibility of bacterial isolates from subclinical mastitis in dairy farms in Kosovo

The aim of this study was to determine the prevalence of subclinical mastitis in dairy cows in Kosovo and the antimicrobial susceptibility of isolated bacteria. Six hundred and twenty four milk samples from individual quarters of 156 lactating cows were tested using California Mastitis Test (CMT) and the positive samples were further analysed using conventional methods for isolation of main mastitis causing agents and finally identified using biochemical tests. The overall prevalence of subclinical mastitis was 25.6%. Twenty one mastitis positive cows belonged to Holstein Friesian breed, 11 to Simmental and 8 were crossbred. Regarding age susceptibility, 13 cows resulting positive in the CMT test were 2–5 years of age and the other 27: 6–9 years of age. A total of 112 bacterial isolates were recovered. The most prevalent species were Staphylococcus aureus (28.6%) followed by coagulase negative staphylococci (21.4%), E. coli (13.4%), Streptococcus agalactiae (14.3%), Streptococcus dysgalactiae (3.6%), Streptococcus uberis (6.2%), Corynebacterium spp. (8%), and Bacillus spp. (4.5%). The isolates were subjected to antimicrobial susceptibility test using the disc diffusion method. In vitro tests of bacterial isolates revealed higher sensitivity to amoxycillin/clavulanic acid, oxytetracycline, trimethoprim and gentamicin. The lowest susceptibility was shown to penicillin and streptomycin except for Corynebacterium spp. and Bacillus spp.

Influence of semen placement location and other factors on the number and morphological status of obtained embryos from donor cows

The aim of the study was to analyze the effectiveness of embryo collection depending on where semen in superovulation cow-donors in heat is deposited. Research was carried out on 44 embryo donors, including 26 heifers and 18 cows of the Polish Holstein-Friesian breed. Manipulations were carried out with the participation of veterinary doctors who specialize in embryo transfer. The estrus cycle of the future donors was synchronized with the double intramuscular injection of 2 ml Cloprostenol (Oestrophan, Biofaktor Company), Dinolytic (Pfizer Polska Sp. z o.o.) 5ml or Bioestrovet (0.5 mg of Cloprostenol – active substance) (Vetoquinol, Biowet Sp. z o.o.) 2 ml administered for 11 days. Superovulation was initiated at day 10th of an estrus cycle – administered by injection of 10ml of FSH (Pluset) during 4 consecutive days (in the morning and in the evening). Estrus was induced on the 3rd day of the superovulation treatment by providing 500µg and 250µg of Cloprostenol (Bioestrovet) twice – 2ml in the morning and 1 ml in the evening. Subsequently, 25 donors were inseminated three times, another 19 were inseminated twice with single or double doses of semen deposited at different locations inside the uterus. Donors were inseminated with frozen semen which is used for standard AI. Obtained results showed a significant influence of placement location of semen on the efficiency of embryos’ collection. The highest ratio (40.4%) of embryos and oocytes was obtained in the case when semen was itself placed in the uterine horn. The lowest ratio (16.2%) was observed in the case when semen was placed in the uterus. Moreover, a difference in the number of obtained oocytes and embryos depends on the sequence of semen placement locations. In the case of location in the uterus body versus uterine horn 0.6 more embryos and oocytes were collected. The number of embryos suitable for transfer was the highest when semen was placed in the uterine horn. Concluding, the uterine horn appeared to be the best place for semen location.

The effect of DGAT1 polymorphism on milk production traits in dairycows depending on environmental temperature

It has long been known that a hot environment negatively influences milk production in cattle. Although molecular mechanisms underlying this phenomenon to a great extent remain to be recognized, they include alterations in lipid metabolism. DGAT1 plays a key role in the synthesis of triacylglycerols and polymorphism of this gene has been proven to have a pronounced influence on milk production. The aim of this study was to establish if the effect of DGAT1:p.K232A on milk-related traits is dependent on environmental thermal conditions. The analysis, performed on 468 cows of the Polish Holstein-Friesian breed, showed that allele DGAT1:K232 significantly increased milk content traits regardless of the temperature. However, its decreasing effect on milk and protein yields as well as the increasing influence on fat yield was not observed in hot weather. Results of this study suggest that the effect of DGAT1:p.K232A on some milk production traits is not constant and may depend on environmental thermal conditions.

Effect of fertility associated proteins on lipid peroxidation production in Holstein Friesian semen

Present study was designed to evaluate effects of fertility associated proteins on sperm motility, viability and level of lipid peroxidation (LPO) in semen. Holstein Friesian breeding bulls (17) were screened for fertility associated proteins (24, 28–30 and 55 kDa proteins), and categorized into 8 groups based on presence/absence in the seminal plasma and sperm membrane. Level of LPO compound malondialdehyde (MDA) was assessed in fresh and frozenthawed semen using thiobarbituric acid method. Fresh semen of bulls positive for fertility associated proteins had lower MDA (0.433±0.03 μmol/ml) than bulls negative for fertility associated proteins (0.740±0.05 μmol/ml). Level of MDA increased in frozen-thawed sperm by 1.5 fold as that of fresh semen among bulls positive for fertility associated proteins and 2 fold in negative bulls. MDA level increased by 27% in all the frozen-thawed semen incubated at 37°C for 180 min, however it was lower in bulls with fertility associated proteins (2.380±0.14 μmol/ ml) than negative bulls. Fresh semen with fertility associated proteins had higher number of motile sperm with progressive motility than negative bulls. Further, bulls with fertility associated proteins were able to sustain higher number of viable sperms with progressive motility than negative group at the end of 180 min of incubation. The results concluded that the fertility associated proteins were capable to sustain sperm viability and motility by limiting LPO production in fresh and frozen-thawed semen.

Evaluation of the Mineral Concentration in Beef from Polish Native Cattle.

The aim of the study was to determine the content of macrominerals and microminerals in the longissimus lumborum (LL) and semitendinosus (ST) muscles of young bulls of five breeds—Polish Red (PR), White-Backed (WB), Polish Black-and-White (PBW), Simmental (SIM) and Polish Holstein-Friesian (PHF). The meat of the Polish Holstein-Friesian bulls was found to contain significantly less K, Mg and Ca and more Mn than other breeds. The meat of the White-Backed bulls contained significantly (P < 0.01) more Ca and less Na than the meat of the Polish Red, Simmental and Polish Holstein-Friesian breeds. Moreover, the meat of White-Backed bulls showed a significantly (P < 0.01) higher level of Mn and Cu in comparison with other native breeds (Polish Red and Polish Black-and-White) and the Simmental breed. Similar content of macronutrients was found in the LL and ST muscles. However, in the case of micronutrients, the LL muscle contained significantly more Zn, Fe and Cu as well as Mn (P > 0.05).

Factors Determining the Susceptibility of Cows to Mastitis and Losses Incurred by Producers Due to the Disease – A Review

Abstract The aim of the paper was to discuss the factors determining the susceptibility of cows to mastitis, the most important for breeders, including losses incurred by milk producers due to the disease. Inflammations of mammary gland are common and the most awkward problem which dairy farmers face around the world. In the case of clinical udder inflammation, it is estimated that the cost of mastitis is about 200 € per cow with fluctuations from 100 even up to 1000 €. Resistance, i.e. the susceptibility of cows to mastitis, is conditioned genetically. The possibility of BoLA and lactoferrin gene polymorphism, using in the selection cows resistant to mastitis, is indicated. Bacteria inhabiting the mammary gland, and the living environment of animals are primarily the main etiological factor. Moreover, many authors indicate the differences between breeds of cows in resistance to mastitis. High-productive breeds are generally more susceptible to the udder inflammation, in comparison to the local breeds. The greatest reduction in milk yield is observed in the case of these breeds, and especially in Holstein-Friesian breed, in which the decline of daily yield at somatic cell count (SCC) amounting above 500,000 per ml of milk can reach 25%. The probability of mastitis occurrence increases with an age of cows and following lactation, and dry period is a time of increased risk. Higher incidence of inflammation is also associated with abnormalities in the construction of the udder (unevenly developed quarters, too long or too short teats). In recent years, a possible relationship between feeding system of cows with their resistance to udder infections has been reported. It is emphasized that a deficiency of selenium and vitamins A and E in the ration may contribute to the increase in the number of mastitis incidences. There are, however, unclear opinions of various authors on the effect of automatic milking system on udder health.

Content of Macro- and Microelements in the Meat of Young Bulls of Three Native Breeds (Polish Red, White-Backed and Polish Black-and-White) in Comparison with Simmental and Polish Holstein-Friesian

Abstract The material for the study consisted of 80 samples taken from the longissimus lumborum (LL) and semitendinosus (ST) muscles of young bulls of five breeds (8 samples of each muscle per breed), including three native breeds included in the genetic resources conservation programme, i.e. Polish Red, White-Backed and Polish Black-and-White, which together with the Simmental and Polish Holstein-Friesian breeds. The content of the elements (K, Na, Mg, Ca, Zn, Fe, Mn, and Cu) analysed in the meat of the young bulls (fattened in a semi-intensive system on fodder from permanent grassland) was found to depend (in varying degrees) on the breed of cattle. The greatest differences (P&lt;0.01 and P&lt;0.05) were noted between the Polish Holstein-Friesians (PHF) and the remaining breeds, mainly in the content of Mg, Ca, Zn and Mn. The results obtained in the four other breeds for most of the macro- and microelements were more uniform, with the highest content noted in the muscles of the young bulls of the native breeds.

Heritability of milk fat composition is considerably lower for Meuse-Rhine-Yssel compared to Holstein Friesian cattle

The aim of this paper is to identify differences in genetic variation of fatty acid (FA) composition in milk in different breeds. Data used included Meuse-Rhine-Yssel (MRY) and Holstein Friesian (HF) cattle breeds which were raised in the Netherlands. Both populations participated in the same milk recording system, but differed in selection history, where in the MRY there has been relatively very little emphasis on selection for high-input high-output production systems compared to HF. Differences in genetic variation were investigated by estimating breed specific additive genetic variances and heritabilities for FA contents in milk of MRY and HF. Mid Infrared Spectrometry spectra were used to predict total fat percentage and detailed FA contents in milk (14 individual FA and 14 groups of FA in g of fat/dL of milk). The dataset for MRY contained 2916 records from 2049 registered cows having at least 50% genes of MRY origin and the dataset used for HF contained 155,319 records from 96,315 registered cows having at least 50% genes of HF origin. Variance components of individual FA content in milk for the different breeds were estimated using a single trait animal model. Additive genetic variances for FA produced through de novo synthesis (short chain FA, C12:0, C14:0, and partly C16:0), C14:1 c-9 and C16:1 c-9 were significantly higher (P<0.001) for HF compared to MRY. Heritabilities of the individual FA, C4:0 to C18:0, for HF ranged from 0.28 to 0.52 and for MRY from 0.17 to 0.34. Heritabilities of the individual C18 unsaturated FA for HF ranged from 0.11 to 0.34 and for MRY from 0.10 to 0.26. Although the mean content in milk for the FA C18:2 c-9, t-11 was low in both breeds, the additive genetic variance in our dataset was significantly higher for MRY (P<0.05) compared to HF. Heritabilities of the groups of FA for HF ranged from 0.19 to 0.53 and for MRY from 0.11 to 0.28. For the majority of the FA, the additive genetic variances for HF were significantly higher compared to MRY, except for most of the poly-unsaturated FA. The results for the poly-unsaturated FA, however, may be affected by the lower accuracy of the predictions for these FA. In conclusion, our results show that the HF breed has substantially larger genetic variance for most FA compared to MRY.

Overlap in genomic variation associated with milk fat composition in Holstein Friesian and Dutch native dual-purpose breeds

The aim of this study was to identify if genomic variations associated with fatty acid (FA) composition are similar between the Holstein-Friesian (HF) and native dual-purpose breeds used in the Dutch dairy industry. Phenotypic and genotypic information were available for the breeds Meuse-Rhine-Yssel (MRY), Dutch Friesian (DF), Groningen White Headed (GWH), and HF. First, the reliability of genomic breeding values of the native Dutch dual-purpose cattle breeds MRY, DF, and GWH was evaluated using single nucleotide polymorphism (SNP) effects estimated in HF, including all SNP or subsets with stronger associations in HF. Second, the genomic variation of the regions associated with FA composition in HF (regions on Bos taurus autosome 5, 14, and 26), were studied in the different breeds. Finally, similarities in genotype and allele frequencies between MRY, DF, GWH, and HF breeds were assessed for specific regions associated with FA composition. On average across the traits, the highest reliabilities of genomic prediction were estimated for GWH (0.158) and DF (0.116) when the 8 to 22 SNP with the strongest association in HF were included. With the same set of SNP, GEBV for MRY were the least reliable (0.022). This indicates that on average only 2 (MRY) to 16% (GWH) of the genomic variation in HF is shared with the native Dutch dual-purpose breeds. The comparison of predicted variances of different regions associated with milk and milk fat composition showed that breeds clearly differed in genomic variation within these regions. Finally, the correlations of allele frequencies between breeds across the 8 to 22 SNP with the strongest association in HF were around 0.8 between the Dutch native dual-purpose breeds, whereas the correlations between the native breeds and HF were clearly lower and around 0.5. There was no consistent relationship between the reliabilities of genomic prediction for a specific breed and the correlation between the allele frequencies of this breed and HF. In conclusion, most of the genomic variation associated with FA composition in the Dutch dual-purpose breeds appears to be breed-specific. Furthermore, the minor allele frequencies of genes having an effect on the milk FA composition in HF were shown to be much smaller in the breeds MRY, DF, and GWH, especially for the MRY breed.

Short communication: Characterization of soluble thiols in bovine milk

Antioxidants are molecules essential for the maintenance of cell homeostasis and their intake through the diet has positive effects on human health. Among antioxidants, low-molecular-weight (LMW) thiols represent an important class of compounds. The aim of this study was to identify LMW thiols in bovine milk. A total of 96 individual milk samples from Brown Swiss, Holstein-Friesian, Alpine Grey, and Simmental cattle breeds were collected in 8 herds. The LMW thiols were extracted from the soluble fraction of milk and, following a derivatization protocol, they were separated by reverse phase HPLC and detected fluorimetrically. Six thiol species were detected and 2, glutathione (GSH) and cysteine-glycine (Cys-Gly), were identified and quantified. Regardless of the breed, the average concentration of Cys-Gly in milk was greater than that of GSH. Overall, milk from dual-purpose breeds (Simmental and Alpine Grey) was richer in LMW thiols than milk from dairy cows (Holstein-Friesian and Brown Swiss). Glutathione and Cys-Gly, closely linked metabolically, were strongly correlated. Pearson correlations of Cys-Gly with protein and casein contents were moderately low, and no relationship was found between GSH and milk chemical composition. Future research should focus on the identification of all detected LMW thiol species.

Association of a genetic marker at the bovine Janus kinase 2 locus (JAK2/RsaI) with milk production traits of four cattle breeds.

In addition to the main components of the somatotrophic axis (GH/GHR/IGF-I/IGF-IR), great importance in the control of growth and development is also attached to the Janus kinase 2 (JAK2) pathway. Induced by the GH/GHR complex, JAK2 activates signal transducer and activator of transcription 5 (STAT5), and in consequence, may be involved in the regulation of expression of insulin-like growth factor I (IGF-I) in the mammary gland. Silent mutation (rs110298451) has been identified within exon 20 using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). A total of 904 individuals of four dairy or dual-purpose breeds (Polish Holstein-Friesian, Montbeliarde, Simmental and Jersey) were genotyped. A genotypic imbalance in the populations was observed. In the case of dual-purpose breeds (Montbeliarde and Simmental), the frequencies of both alleles were almost equal. In contrary, the JAK2G allele was predominant in the Polish Holstein-Friesian breed while JAK2A allele in Jersey. A pronounced relationship between JAK2/RsaI polymorphism and milk production traits was found where, irrespective of breed and lactation order, the GG genotype was significantly associated with higher milk, protein and fat yields, as compared to the AA genotype. Heterozygous individuals were generally characterised by intermediate values of the analysed milk traits. It can be argued that the JAK2 gene polymorphism is a potential marker for milk production traits. However, due to the fact that rs110298451 SNP does not directly affect amino acid sequence, other association studies involving missense mutation should also be performed.