Polish Holstein-Friesian Cows Research Articles

Composition and fatty acid profile of milk from cows fed diets supplemented with raw and n-3 PUFA-enriched fish oil

Dietary supplementation of ruminants with fish oil is a strategy for favorably modifying the fatty acid composition of milk fat. This study investigated the effect of supplementing cows’ diet with fish oil after low-temperature crystallisation (LTC-FO) compared to its raw form (FO) on milk yield, milk components (fat, protein, and lactose), and milk fatty acid profile. Twenty-four mid-lactating multiparous Polish Holstein–Friesian cows fed a total-mix ration were randomly assigned to two homogeneous groups (n = 12 cows each) and supplemented with LTC-FO or FO at 1% of dry matter. Milk samples were collected on days 14 and 30 of the 30-day experiment. No significant differences between the groups in terms of milk yield, milk protein, and lactose content were found, however, the fat yield and content decreased in the LTC-FO group. Milk fat from cows in the LTC-FO group contained significantly higher levels of C18:1 trans-11, C18:2 cis-9, trans-11, C18:3n − 3, C20:5, and C22:6, and lower levels of saturated fatty acids compared to the FO group (p < 0.05). Therefore, LTC-FO may be a more efficient feed additive than FO and may serve as a practical way to modify the fatty acid composition of milk fat.

The use of stem cells in the treatment of mastitis in dairy cows

Mastitis is a multifactorial inflammatory disease. The increase in antibiotic resistance of bacteria that cause mastitis means that cattle breeders would prefer to reduce the use of antibiotics. Recently, therapies using mesenchymal stem cells (MSCs) from various sources have gained significant interest in the development of regenerative medicine in humans and animals, due to their extraordinary range of properties and functions. The aim of this study was to analyze the effectiveness of an allogeneic stem cells derived from bone marrow (BMSC) and adipose tissue (ADSC) in treating mastitis in dairy cattle. The research material consisted of milk and blood samples collected from 39 Polish Holstein-Friesian cows, 36 of which were classified as having mastitis, based on cytological evaluation of their milk. The experimental group was divided into subgroups according to the method of MSC administration: intravenous, intramammary, and intravenous + intramammary, and according to the allogeneic stem cells administered: BMSC and ADSC. The research material was collected at several time intervals: before the administration of stem cells, after 24 and 72 h, and after 7 days. Blood samples were collected to assess hematological parameters and the level of pro-inflammatory cytokines, while the milk samples were used for microbiological assessment and to determine the somatic cells count (SCC). The administration of allogeneic MSCs resulted in a reduction in the total number of bacterial cells, Staphylococcus aureus, bacteria from the Enterobacteriaceae group, and a systematic decrease in SCC in milk. The therapeutic effect was achieved via intravenous + intramammary or intramammary administration.

The effectiveness of using bulls with increased immune response in terms of milk yield, milk contents, and somatic cell count in Polish Holstein-Friesian cows

Abstract The dairy cattle industry has witnessed significant advancements in production traits, including milk yield, reproduction, and health, through decades of breeding efforts. Despite these improvements, cow health and milk hygiene remain essential. High Immune Response (HIR) technology identifies cattle with optimized immune responses, enabling the selection of bulls with high immune responses for breeding. Studies indicate that HIR-based breeding improves animal health without compromising production traits. This study aimed to assess the effectiveness of bulls with a high immune response (HIR) in improving milk yield, milk contents, and somatic cell count in the milk of Polish Holstein-Friesian cows. A total of 11,509 cows of the Polish Holstein-Friesian breed were used. Among those, 1,773 animals were the offspring of HIR bulls, including 926 first-generation offspring (called I50 group) and 847 second-generation offspring (I25 group). There were 9,736 animals unrelated to HIR bulls (I0 group). Selected production and functional traits were analyzed. The results show that cows with higher kinship to HIR bulls showed increased milk yield. However, their milk exhibited lower fat, protein, and casein content. A favorable impact of HIR bulls was demonstrated by the decrease in somatic cell count in their offspring’s milk compared to the milk of cows from the I0 group. This research contributes valuable insights into the potential benefits of using HIR bulls in dairy cattle breeding programs, emphasizing the importance of balancing production traits with health considerations.

Comparison of BoLA-DRB3 genetic diversity among Polish Red-and-White (PRW) and Polish Holstein-Friesian (PHF) cattle

Abstract Cattle breeding in Poland, including the maintenance of indigenous breeds, is exposed to the occurrence of many diseases of infectious and non-infectious etiologies. Bovine MHC (BoLA)-DRB3 is a highly polymorphic gene that plays an important role in the immune response to antigens. This pilot study aimed to analyze BoLA-DRB3 genetic diversity among Polish Red-and-White (PRW) and Polish Holstein-Friesian (PHF) cattle. DNA sequencing revealed haplotypes for 48 out of 106 PRW and 10 out of 26 PHF cows. Analysis indicated 42 alleles detected in the PRW breed and 16 in the PHF animals. Interestingly, within the PRW breed three alleles BOLA03100|BoLADRB3* 001:01|554, BOLA03113|BoLA-DRB3*009:02|270 and BOLA03302|BoLA-DRB3*049:01|236 were observed in 24 cows. Overall, the presented study demonstrated the genetic diversity of the BoLA-DRB3 gene in the indigenous Polish Red-and-White cattle breed for the first time. The acquired results broaden the knowledge of BoLA-DRB3 diversity in cattle, whose genetic variants promote resistance or susceptibility to viral or bacterial diseases.

Performance comparison of machine learning models used for predicting subclinical mastitis in dairy cows: Bagging, boosting, stacking, and super-learner ensembles versus single machine learning models

Mastitis has a substantial impact on the dairy industry across the world, causing dairy producers to suffer losses due to the reduced quality and quantity of produced milk. A further problem, related to this issue, is the excessive use of antibiotics that leads to the development of resistance in different bacterial strains. The growing consumer awareness oriented toward food safety and rational use of antibiotics has promoted the search for new methods of early identification of cows that may be at risk of developing the disease. Subclinical mastitis does not cause any visible changes to the udder or milk, and therefore it is more difficult to detect than clinical mastitis. The collection of large amounts of data related to milk performance of cows allows using machine learning (ML) methods to build models that could be used for classifying cows into healthy and at risk of subclinical mastitis. The data used for the purpose of this study included information from routine milk recording procedures. The data set consisted of 19,856 records of 2,227 Polish Holstein-Friesian cows from 3 herds. The authors decided to use the approach of building ensemble ML models, in particular bagging, boosting, stacking and super learner models, and comparing them for accuracy of identification of disease-affected cows against single ML models based on the Support Vector Machines, Logistic Regression, Gaussian Naïve Bayes, k-Nearest Neighbors and Decision Tree algorithms. The models were trained and evaluated based on the information recorded for herd 1 and using an 80:20 train-test split ratio according to animal ID (to avoid data leakage). The information recorded for herds 2 and 3 was only used to evaluate on unseen data models developed using the herd 1 data set. Among the single ML models, the Support Vector Machines model was found to be the most accurate in predicting subclinical mastitis at subsequent test-day when used both for the training set (mean F1-score of 0.760) and the testing sets containing data for herds 1, 2 and 3 (F1-score of 0.778, 0.790 and 0.741 respectively). The Gradient Boosting model was found to be the best performing model among the ensemble ML models (F1-score of 0.762, 0.779, 0.791 and 0.723 for the training set and the testing sets respectively). The super learner model, featuring the most advanced design and Logistic Regression in the meta layer, achieved the highest mean F1-score of 0.775 during the cross-validation, however, it was characterized by a slightly worse prediction accuracy of the testing sets (mean F1-score of 0.768, 0.790 and 0.693 for herds 1, 2 and 3 respectively). The study findings confirm the promising role of ensemble ML methods that were found to be slightly superior with respect to most of the single ML models.

The effect of heat stress on performance, fertility, and adipokines involved in regulating systemic immune response during lipolysis of early lactating dairy cows

The aim of this study was to assess the potential effect of heat stress on dairy cow productivity, fertility, and biochemical blood indices during the early lactation stage in a temperate climate. Additionally, the study aimed to determine the role of leptin and adiponectin in regulating the immune response accompanying lipolysis after calving in dairy cows. The study included 100 clinically healthy Polish Holstein-Friesian dairy cows selected based on parity and 305 d of milk yield from 5 commercial farms with similar herd management and housing systems. Prospective cohort data were recorded from calving day until 150 d in milk, and microclimate loggers installed inside the barns were used to record temperature and relative humidity data to calculate daily temperature-humidity index (THI) on the calving day, through +7, +14, and +21 d during early lactation. Additionally, monthly productive performance parameters such as milk yield, chemical composition, fatty acids composition, and fertility indices were analyzed. Results showed that the THI from calving day through +7, +14, and +21 d during early lactation was negatively associated with fertility parameters such as delayed first estrus postpartum and an elongated calving interval, respectively, by 29, 27, 25, and 16 d. Furthermore, an increase in THI value during early lactation was associated with an elongated artificially inseminated service period, days open, and intercalving period. Increasing THI from calving day (0 d) through +7, +14, and up to +21 d during early lactation was also linked to decreased milk yield by 3.20, 4.10, 5.60, and 5.60 kg, respectively. The study also found that heat stress during early lactation was associated with a lower body condition score in dairy cows and higher concentrations of leptin, nonesterified fatty acids, and β-hydroxybutyrate, accompanied by a drastic reduction in adipose tissue-secreted adiponectin levels after calving. Additionally, heat stress-induced lipolysis in adipose tissue caused an inflammatory response that increased biochemical blood indices associated with immune responses such as cytokines, acute phase proteins, and heat shock protein. These findings suggest that exposing dairy cows to heat stress during early lactation can negatively affect their productive performance, fertility, and biochemical blood indices in subsequent lactations. Thus, farm management changes should be implemented during early lactation to mitigate the negative consequences of heat stress occurrence.

Effect of fluidised dried yeast (&lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt;) supplementation on milk composition, somatic cell count and milk yield at different lactation stages in Polish Holstein-Friesian cows

Effect of fluidised dried yeast (&lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt;) supplementation on milk composition, somatic cell count and milk yield at different lactation stages in Polish Holstein-Friesian cows

WPŁYW KOLEJNEJ LAKTACJI ORAZ ŚREDNIEJ DOBOWEJ WYDAJNOŚCI MLEKA W LAKTACJI PEŁNEJ KRÓW RASY POLSKIEJ HOLSZTYŃSKO-FRYZYJSKIEJ NA DŁUGOŚĆ OKRESU ZASUSZENIA

The aim of the study was to determine the effect of average daily milk yield in complete lactation and lactation number in cows producing at least 8,500 kg of milk in 305-day lactation on the length of the dry period before the next lactation. A total of 1,965 complete, extended lactations in Polish Holstein-Friesian cows subject to use value assessment were analysed. The average complete-lactation daily milk yield was shown to influence the length of the dry period. The average dry period length was 44 days. Dry period length decreased in successive milk-yield groups, from 50 days (average daily yield up to 25 kg of milk) to 28 days (average daily yield over 35 kg in complete lactation). Thus it was confirmed that as milk yield increased, it was more difficult to end lactation. The shortest dry period (only 25 days) was recorded in the youngest cows (second and third lactation) with the highest average daily milk yield in complete lactation (&gt;35 kg). In the oldest cows, i.e. those in their sixth lactation and higher, no statistically significant differences were shown in the length of the dry period depending on daily yield.

IDENTYFIKACJA POLIMORFIZMÓW POJEDYNCZEGO NUKLEOTYDU W OBR ˛EBIE GENÓW KODUJ ˛ACYCH BAKTENCYN ˛E-5 I BAKTENCYN ˛E-7 W POWI ˛AZANIU Z CECHAMI PRODUKCJI MLEKA

Bactencins belong to the bovine cathelicidin family of proteins, and their role in the body is significant. The study analyzed the relationship between polymorphisms within the CATHL2 and CATHL3 genes encoding the Bac-5 and Bac-7 proteins. The study included a herd of Polish Holstein-Friesian cows of the black-and-white breed. Tests were conducted using the PCR-RFLP method with the introduction of the ACRS modification. The study showed that different genetic variants within the polymorphisms studied were significantly associated with selected parameters of milk performance, such as milk yield (P ≤ 0.01), fat (P ≤ 0.01), protein (P ≤ 0.01 and P ≤ 0.05) and lactose (P ≤ 0.01 and P ≤ 0.05) content and somatic cell count (P ≤ 0.01 and P ≤ 0.05).

Genetic relationships of body condition score and locomotion with production, type and fertility traits in Holstein-Friesian cows

New traits are sought to add in breeding goals to prevent worsening health and fertility of Polish Holstein-Friesian cows. The objectives of this study were to estimate genetic parameters for body condition score (BCS) and locomotion (LOC) and their relationship with other type traits, milk and fertility traits, and to show genetic trends for BCS and LOC in Polish Holstein-Friesian population. Data on 317 028 Holstein-Friesian cows, born from 2010 through 2015 in 11 792 herds, were collected. All cows were scored for BCS and 43% of them for LOC. All records comprised lactational yields of milk, fat and protein, content of fat and protein and somatic cell count from the first three lactations, stature, five composite and 16 linear conformation traits, and four fertility traits. Genetic parameters were estimated using a Bayesian method with Gibbs Sampling, generating 100 000 samples in each of four steps: BCS and LOC with five composite conformation traits, BCS and LOC with 16 linear conformation traits, BCS and LOC with production traits, and BCS and LOC with four fertility traits. The linear model for BCS and LOC contained fixed effects of herd-year-season-classifier and lactation stage, fixed linear and quadratic regressions on age at calving, fixed linear regression on the percentage of Holstein-Friesian genes, and random additive genetic effect. Breeding values for BCS and LOC were calculated using the same model as used for estimation of genetic parameters. Genetic trends for BCS and LOC, defined as regression coefficients of mean breeding value on birth year, were examined. BCS was a moderately heritable trait (0.19) and was genetically correlated with non-return rate until 56 days after first insemination for cows (−0.32) and with days open (−0.22), so selection for BCS might have a favourable correlated effect on fertility. LOC, lowly heritable (0.06), was relatively strongly genetically correlated with feet-and-legs traits (from 0.48 to 0.93, ignoring sign) and could be included in a selection subindex for feet-and-legs. The positive trend for LOC indicated substantial progress towards the highest genetic value (optimum at the end of the scale), while the small trend for BCS showed a tendency to stabilise the average value in the middle of the scale (optimum for BCS). The estimates of the genetic parameters for BCS and LOC indicate that both traits could contribute to more effective selection to improve fertility (BCS) and legs health (LOC) in the Polish dairy cattle population.

Effects of raw and fermented rapeseed cake on ruminal fermentation, methane emission, and milk production in lactating dairy cows

The objective of this study was to evaluate the effects of replacing raw rapeseed cake (RC) with fermented rapeseed cake (FRC) in the diet of dairy cows on methane (CH4) production, ruminal fermentation, and milk production, composition, and fatty acid composition. The Hohenheim gas test (exp. 1) was initially used to evaluate RC and FRC as substrates. Following batch fermentation, an in vitro study (exp. 2) was performed to assess the effects of replacing RC with FRC at 28.75, 57.5, 86.25, and 115 g/kg (FRC25, FRC50, FRC75, and FRC100) in the total mixed rations (TMR). Based on the in vitro results, the control TMR (115 g/kg dry matter (DM) of RC; CONRC) and experimental TMR (115 g/kg DM of FRC; FRC100) were chosen for an in vivo assessment. In exp. 3, four ruminally cannulated cows were used in a replicated 2 (group) × 2 (period) crossover design and fed the TMR ad libitum. In exp. 4, twenty multiparous Polish Holstein-Friesian cows in their mid-lactation (148 ± 26 d in milk) were used in a completely randomized design. The cows were fed a partial mixed ration without the RC and FRC, and the RC and FRC were supplied in a concentrate feeder at 2.65 kg/d/cow. The FRC100 markedly decreased CH4 production by 12% and archaeal population without adversely affecting nutrient digestibility. The molar proportion of propionate was increased, and the molar proportion of acetate and butyrate and acetate to propionate ratio were decreased by FRC100. No significant effects on milk production or composition, except an increase in milk urea concentration, were observed in cows fed FRC100. Milk C18:2 cis-9, trans-11 concentration was greater, and n-6 to n-3 fatty acid ratio was lower for FRC100 than CONRC. In-situ ruminal degradation of RC and FRC were explored using in-sacco techniques (exp. 5). The potential degradation and effective degradability of the DM, organic matter, and crude protein were significantly higher for FRC than RC. These results suggested that FRC could mitigate enteric CH4 production by decreasing archaeal abundances without adversely affecting milk production and ruminal fermentation in lactating cows.

EVALUATION OF LACTATIONAL EXCRETION OF UREA AND AMMONIA IN DAIRY CATTLE HERDS

The aim of the study was to evaluate the lactational unit production of urea and ammonia emissions from cows kept in eastern Poland. The study covered 1089 lactations of Polish Holstein-Friesian cows born between 1992 and 2018 in 15 cattle herds located in the Mazovia and Podlasie voivodships. The amount of urea excreted in urine and nitrogen compounds in cow feces was calculated based on the following regression equations: (y = 15.46 urea concentration in milk (g/L) + 193.4); y = 11.42 urea concentration in milk (g/L) + 41.93); y = 4.05 urea concentration in milk (g/L) + 151.47). Several factors affecting the total production of urea were examined. Four groups of animals were distinguished according to their milk yield from a 305-day lactation (&lt;6000; 6001-8000; 8001-10000; &gt;10000 kg); three groups based on year of birth (1992-2000; 2001-2010; 2011-2018); four age groups (first lactation; second lactation; third lactation; fourth to twelfth lactation); and three groups according to urea content in milk (1-150; 151-250; &gt;250 mg/L). The results of the study showed that the average concentration of urea in cow urine was 78.6 kg and the ammonia emission from a lactating cow was 44.6 kg. The study demonstrated a large variation in the amount of nitrogen compounds excreted in feces and the degree of ammonia emission risk among animals. The main factors differentiating the amount of nitrogen compounds in urine and feces and the level of ammonia emission into the atmosphere included the cow's production level, year of birth, and urea content in milk.

Effect of repeated low doses of GnRH analogue (buserelin) on fertility performance of dairy cows with anovulation type I.

The aim of this study was to evaluate the fertility response of dairy cows with anovulation type I on repeated low doses of GnRH agonist buserelin. The study was conducted on 83 anovulatory and 60 cyclic Polish Holstein Friesian cows. Anovulation type I was defined as small ovaries with follicles of ≤ 5 mm in diameter and without corpus luteum on two examinations in a 7-10 day interval between 50-60 days after parturition. Cows from the experimental group (n=58) received 0.4 μg of buserelin i.m. once a day for 5 consecutive days. Cows from the negative control group (n = 25) received saline. Sixty cyclic cows receiving no treatment served as positive controls. Intervals from calving to estrus and from calving to conception, pregnancy rate 30-35 days and 260 days after AI, and pregnancy loss were calculated. The anovulatory cows had a substantially prolonged calving to conception interval, decreased pregnancy rate and increased pregnancy loss and culling rate compared to cyclic herd mates. The average calving to conception interval was significantly (p⟨0.05) shorter in treated cows compared to non-treated anovulatory cows (153.7 days vs 209.3 days). In conclusion, repeated low doses of GnRH analogue buserelin led to a significant shortening of calving to conception interval. More clinical trials are needed to determine the practical usefulness of this method for the treatment of anovulation type I in dairy cows.

The Effect of Parity on the Quality of Colostrum of Holstein Dairy Cows in the Organic Production System.

A special feature of organic production systems is the cows' significantly lower productivity, which is adapted to environmental conditions. The quantity and quality of colostrum is negatively correlated, high amounts of colostrum are associated with low amounts of immunoglobulins. Cows' parity is also a modulating factor, and studies have shown an increase in colostral IgG corresponds with increasing parity. This study's aim was to determine the effect of cows' parity on colostrum quality, in an organic farm setting. From a basic organic herd of dairy cattle, 40 Polish Holstein-Friesian cows were selected: 10 cows each of primiparous, second lactation, fourth lactation, and fifth lactation. Colostrum and transition milk samples were taken from each cow seven times: twice daily on the 1st and 2nd days after calving (every 12 h), and once daily on the 3rd to 5th days. Multiparous cows' colostrum had higher levels of total proteins, casein, and non-fat dry matter, versus primiparous. Only cows in the second and fourth lactations produced very good quality colostrum (with immunoglobulins over 50 g/L), meeting standards for immunoglobulin concentration. In conclusion, the production of very good quality colostrum is limited during the first lactation, which may suggest the mammary gland is poorly developed, and, thus, immunoglobulin transport is limited. Variability in the colostrum's immunoglobulin content from first and second collections post-calving was higher in multiparous versus primiparous cows. Therefore, it should be good practice to freeze colostrum from multiparous cows in case of poor-quality primiparous colostrum.

Comparison of blood gas parameters, ions, and glucose concentration in polish Holstein-Friesian Dairy cows at different milk production levels

Genetic selection for increased milk yield has been a key driver of dairy intensification. The modern dairy cow produces much higher amounts of milk than the cattle of several years ago, and this may have an influence on hematologic values at different stages of lactation and on cows with different levels of milk production. The purpose of the study was to investigate the variations in blood parameters such as Ht, tHb, sO2, FO2Hb, FCOHb, FMetHb, FHHb, pH, pCO2, pO2, standard HCO3−, actual HCO3−, BE, BE ecf, ctCO2, BO2, p50, and ctO2 in cows at different milk production levels. In addition, ions such as Na+, K+ , Ca++, Ca++ (7.4), and Cl−, and AnGap and glucose were examined. Our findings indicated that differences in the examined blood parameters between low and high-production dairy cattle do exist. The most apparent differences were connected with blood pH (p < 0.01), oxygen metabolism (Ht, tHb, sO2, FO2Hb; p < 0.01), and glucose utilization (p < 0.01) The results confirm that the parameters connected with blood oxygen metabolism and glucose metabolism increase significantly in high-production animals. In conclusion, reference values should be considered in light of the lactation stage and level of milk production, because these might influence how changes should be interpreted. The main limitation of the study is the delay to analysis. However, the blood was properly stored (4C), thus changes were delayed. Anyway, it is very hard in the field practice to perform it within 5 min after the blood collection and according to studies it has low impact on clinical outcomes.

Effect of Bear Garlic Addition on the Chemical Composition, Microbiological Quality, Antioxidant Capacity, and Degree of Proteolysis in Soft Rennet Cheeses Produced from Milk of Polish Red and Polish Holstein-Friesian Cows.

This study aimed to assess the effect of milk source and bear garlic addition on the selected properties of soft rennet cheese. Cheeses were produced from cow milk derived from two sources: Polish Red cows (PR) and Polish Holstein-Friesian cows (PHF) with a 0.5% (w/w) addition of bear garlic (Allium ursinum L.) dried leaves. Chemical composition and fatty acid profiles (GC) were determined in fresh cheeses. Fresh and stored for two weeks cheeses were subjected to microbiological studies, i.e., total aerobic bacteria count (TABC); count of Lactococcus sp., yeast and molds; coliforms; analysis of the proteolysis extension by means of o-phthaldialdehyde (OPA) assay and free amino acids content (HPLC); antioxidant capacity as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP); as well as pH and water activity. Cheeses with bear garlic herbs were more prone to proteolysis but this was not accompanied by any effect on the microbial counts, water activity or pH. Cheeses produced from PR milk contained less monounsaturated fatty acids (MUFA) but were richer in n-3 PUFA and had a lower n-6/n-3 FA ratio than cheeses from PHF milk. Bear garlic addition increased DPPH anti-radical power but had less of an effect on the FRAP values.

WYKORZYSTANIE WYTRWAŁOŚCI LAKTACJI JAKO WSKAŹNIKA W SELEKCJI LINII MATECZNYCH KRÓW RASY HF

The research material for this study consisted of a group of 163 Polish Holstein Friesian cows (PHF). For the study, the cows were assigned to 14 maternal lineages covering three genera- tions. The aim of this study was to indicate possibilities for selecting cows with the goal of maintaining lineages on the farm which are characterised high productive qualities based on lactation persistency index. Basic milk parameters were analysed over a 305-day lactation cycle and information on somatic cell content was also gathered based on sample milkings. A characterisation of lactation persistency for a given lactation was generated as a percent difference between milk yield in the 2nd and 10th month of lactation, and a lactation persistency curve was developed for particular lineages in succes- sive lactations, representing changes in the productivity of the cows. It was determined that together with increasing numbers of lactations among the cows studied, the average lactation persistency index also increased. For younger cows, this index did not exceed 30%, while in the older group this index amounted to 70%. Cows with the highest lactation persistency values 70.1–80% were also char- acterised by the highest milk production in average daily milk yields during peak lactation, amount- ing to 56.14 kg at values of for the index. Cows which began their milk production stage with a high persistency index in the 1st and 2nd lactations, in successive lactations saw a significant decrease in this index. Breeding cattle within maternal lines characterized by a high and stable level of lactation persistence index can ensure a high level of milk production in this line of cows.

Prevalence of subclinical endometritis in dairy cows that recovered after treatment of clinical endometritis with cephapirin and PGF2α

The aims of our study were to evaluate (1) the prevalence of subclinical endometritis (SE) in clinically cured cows after treatment of clinical endometritis (CE) with uterine cephapirin infusion or with systemic application of PGF2α and after self-healing, (2) the prevalence of SE in clinically cured cows in relation to the type of vaginal discharge. The study was conducted on 222 Polish Holstein Friesian cows with CE diagnosed by vaginoscopy and ultrasound. The animals were randomly allocated to one of three groups: Group 1 (n = 72): intrauterine cephapirin infusion; Group 2 (n = 73): single intramuscular injection of dinoprost; and Group 3 (n = 77): left untreated as a control. All cows were reexamined two weeks later (Exam 1). If there was still CE at this examination, these cows were treated using the same method as previously and were examined 2 weeks later (Exam 2). Cows still having CE at the second examination were examined two weeks later (Exam 3). Cows without signs of CE at Exams 1, 2 and 3 were considered cured, and endometrial samples from the uteri were collected by cytobrush to diagnose SE using cytological evaluation of PMN percentage. The threshold for SE was set at ≥ 5% PMNs. Two cows each from Groups 1 and 3 and three cows from Group 2 were not clinically recovered at Exam 3 and were excluded from the analysis. In total, SE was diagnosed in an average of 40.9% of clinically cured cows. The prevalence of SE in Group 1, 2 and 3 was 35.0%, 47.1% and 40.0%, respectively (p > 0.05). There were significantly higher (p < 0.05) SE cases after treatment of CE associated with purulent vaginal discharge than with mucopurulent discharge. In relation to the method of treatment, the prevalence of SE was significantly higher (p < 0.05) in cows treated with cephapirin with purulent vaginal discharge than with mucopurulent vaginal discharge. In conclusion, the study showed a high prevalence of SE in cows clinically cured after treatment of clinical endometritis with cephapirin or PGF2α and after self-healing. The prevalence of SE was significantly higher in cows with purulent vaginal discharge than with mucopurulent vaginal discharge. Therefore, in cows clinically recovered from clinical endometritis, the prevalence of SE should always be considered a negative consequence, and the resulting management of this uterine disease should be implemented at the herd level.

Genetic Parameters for Methane Emissions Using Indirect Prediction of Methane and Its Association with Milk and Milk Composition Traits.

Simple SummaryMethane is a major source of greenhouse gases, and ruminant animals are mainly responsible for its emission. Measuring methane in a large group of animals is expensive and requires specialised equipment. Therefore, direct animal selection aiming at reducing methane production by dairy cows on a large scale is difficult. This study aims to predict methane production based on milk yield production, estimate heritability for methane production, and the genetic correlation between methane production and milk production. The indirect approach using milk traits and genetic parameters shows that methane production is a heritable trait. High genetic correlations were estimated between methane production and milk traits. That indicates the selection to decrease methane production would also negatively affect milk yield and composition.The study covers milk yield and composition data for 17,468 Polish Holstein-Friesian cows. Methane production (g/lactation per cow, MP) for dairy cow were predicted using three methane production equations (MPE) that took into account: milk yield (MPE1), energy corrected milk (MPE2) and both milk protein concentration (%), and energy-corrected milk (MPE3). The average amounts of methane produced for each cow per lactation were 31,089 g, 46,487 g, and 51,768 g for MPE1, MPE2, and MPE3, respectively. Repeatability models were used to estimate genetic parameters for MP. The estimated heritabilities for MPE1, MPE2, and MPE3 were 0.30, 0.24, and 0.24, respectively, with a standard error of 0.01. High genetic correlations (>0.76) were obtained between methane and milk yield, protein, fat, lactose and dry matter contents in milk for MPE1, MPE2 and MPE3. Still, a moderate genetic correlation (0.34) was obtained between methane and fat content (MPE1); the standard error of the estimated genetic correlation was less than 0.05. The results of the current study indicate that genetic selection aimed to reduce MP in dairy cows is possible. However, such direct genetic selection could cause a negative genetic response in milk yield and composition due to negative genetic correlations between MP and milk yield and composition.

The optimal level of factors for high daily milk yield in automatic milking system

Optimising daily milk yield in automatic milking systems (AMS) became one of the basic issues raised by many farmers. The aim of this study was to determine the best combination of factors and their levels suggested by the decision tree for high daily milk yield per AMS in dairy cattle herds. The study involved 4854 Polish Holstein-Friesian cows milked in 20 barns with Lely AMS. Statistical analysis was performed using two methods: multifactorial analysis of variance and classification tree technique. Milk yield, number of cows, free robot time, milking speed, and cow treatment time (i.e. cleaning of teats before and after milking) were the significant determinants of total milk yield for all cows per milking robot and were most frequently used to construct the decision tree. The tree shows that the highest total milk yield per robot was observed for the group of cows that produced more than 30 kg of milk per day, with a milking speed of over 2.40 kg/min. and during robot days in which free time did not exceed 10% of the day. In AMS dairy herds, efforts should be made to select animals that transmit high milk yield and high milking speed while shortening free robot time and increasing daily milk yield per robot. Also, attention should be given to the percentage of box time spent on preparing the cow for milking and after milking because prolongation of this variable has a negative effect on daily milk yield per AMS.