Polish Holstein-Friesian Breed Research Articles

The Influence of Selected Environmental Factors on the Number of Somatic Cells in Cistern and Alveolar Milk of Polish Holstein-Friesian Cows.

The aim of the study was to evaluate the influence of the milking phase on somatic cell count (SCC) in milk obtained from the cisternal and alveolar parts of udders of selected Polish Holstein-Friesian cows. The study also assessed the impact of other genetic and environmental factors on SCC variability in cisternal and alveolar milk, including: the individual cow, lactation stage, age of cow, production level, milking speed, fat-to-protein ratio, and milking type. The research included 15 cows of Polish Holstein-Friesian breed at different ages, lactation stages, and with varying daily milk yield. A total of 210 milk observations were conducted, including 105 for 1 min milking and 105 for 8 min milking. The results obtained in the study indicated that milk obtained during two different milking phases exhibited similar SCC levels (F for LOGSCC = 0.79). The average actual SCC in milk produced by 15 cows in 105 observations for 1 min milking was 219,000 cells/mL, while for 8 min milking it was 229,000 cells/mL. The results were inconclusive, suggesting that SCC in cisternal and alveolar milk must be influenced by factors other than the milking phase. The analysis of variance conducted for this purpose provided the basis for stating a highly statistically significant effect of the individual cow (F for LOGSCC = 147.9), lactation stage (F for LOGSCC = 54.64), age of cow (F for LOGSCC = 12.39), daily production level (F for LOGSCC = 34.49), milking speed (F for LOGSCC = 17.56), and fat-to-protein ratio (F for LOGSCC = 22.99) on the variability of characteristics defining SCC in milk. In summary, SCC is characterized by high variability, influenced by a range of environmental and genetic factors such as the individual cow, lactation stage, age of cow, milking speed, and dietary fat-to-protein ratio. The influence of milking phase (1 min or 8 min) and milking type (morning or evening) should be considered inconclusive based on the entire population studied. For half of the cows, SCC in cisternal milk was higher than in alveolar milk, while for the other half, the situation was reversed. Further observations are required to confirm the hypothesis regarding the extent to which cows' immunological response to bacterial infections is concentrated in the cisternal or alveolar part of the udder under national environmental conditions.

Gene Expression Level and Immunohistochemical Localization of Cannabinoid and Cannabinoid-Related Receptors in The Small Intestine of Holstein Bulls (Bos Taurus Taurus)

Abstract The gastrointestinal tract plays a crucial role in nutrient absorption, secretion, and motility, ensuring proper digestion and overall homeostasis. Regulation of this complex system involves the coordination of various communication pathways, including neural and humoral mechanisms. One such mechanism is the endocannabinoid system (ECS), a signaling network comprising endogenous cannabinoids, receptors, and enzymes involved in the regulation of physiological processes in mammals and non-mammalian species. While extensive research has been conducted on the ECS in monogastric animals, limited information is available on its presence and distribution in cattle. This study aimed to investigate the distribution and localization patterns of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R) and transient receptor potential vanilloid type 1 (TRPV1) in the bovine small intestine. The study included immunohistochemical analysis of intestinal tissue samples from Polish Holstein-Friesian breed bulls. Gene expression levels of CNR1, CNR2, and TRPV1 genes, encoding CB1R, CB2R, and TRPV1, respectively, were quantified using qPCR analysis. The results showed that all three receptors were expressed in the bovine small intestine, with TRPV1 exhibiting a significant upregulation in the jejunum compared to the duodenum and ileum. Immunoreactivity for CB1R and CB2R was predominantly observed in neurons of the enteric plexuses, while TRPV1 immunolabeling was detected in both enteric neurons and duodenal Brunner’s glands. These findings may establish an anatomical foundation for further investigations, lending support to the potential therapeutic efficacy of cannabinoid receptor agonists in alleviating gastrointestinal motility disorders associated with bovine enteropathies and optimizing milk production in dairy cattle.

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 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.

Heritability and genetic correlations of rumination time with milk-yield and milking traits in Holstein-Friesian cows using an automated milking system

Knowledge of the values of genetic parameters is a prerequisite for conducting a breeding program. This is especially important for rumination, which is considered an indicator of cow’s health. Exploring the genetic relations between rumination time, milk yield, and milking traits could make it a valuable tool in dairy cattle breeding strategies. The objective of the research was to estimate heritability, repeatability, and genetic and phenotypic correlations of rumination time (RT), as well as traits associated with milk yield and milking of dairy cows of the Polish Holstein-Friesian breed kept in herds equipped with an automatic milking system. The research takes into consideration daily results for milking in the first lactation and second lactation, from 1 486 cows of the breed milked between 2013 and 2015 year. Cows were housed in 24 free-stall barns and fed a Partial Mixed Ration feed. The barns had an automated milking system (Astronaut A4 – Lely Industry). The cows received a varied dose of the concentrate, either in the milking robot or the feeding station, depending on the level of their milk yield. Our research has shown that RT was a low heritable trait (0.140 ± 0.039) and had a medium repeatability (0.572 ± 0.007). We detected a positive genetic correlation between RT and milk yield (0.341); however, a statistically significant negative relationship was identified between RT and urea content (−0.418) in milk. Estimations of genetic correlations suggest that selecting for higher RT may correspond to reduced urea content in milk. Investigating the genetics aspect of RT and the relationship with milk yield and milking traits may turn this into one of the useful criterion selections for dairy cattle breeding strategies, but should be used carefully. Further analyses on larger data sets and different populations are necessary.

Expression of Genes Encoding Selected Orexigenic and Anorexigenic Peptides and Their Receptors in the Organs of the Gastrointestinal Tract of Calves and Adult Domestic Cattle (Bos taurus taurus).

The regulation of food intake occurs at multiple levels, and two of the components of this process are orexigenic and anorexigenic peptides, which stimulate or inhibit appetite, respectively. The study of the function of these compounds in domestic cattle is essential for production efficiency, animal welfare, and health, as well as for economic benefits, environmental protection, and the contribution to a better understanding of physiological aspects that can be applied to other species. In this study, the real-time PCR method was utilized to determine the expression levels of GHRL, GHSR, SMIM20, GPR173, LEP, LEPR, and NUCB2 (which encode ghrelin, its receptor, phoenixin-14, its receptor, leptin, its receptor, and nesfatin-1, respectively) in the gastrointestinal tract (GIT) of Polish Holstein-Friesian breed cattle. In all analyzed GIT segments, mRNA for all the genes was present in both age groups, confirming their significance in these tissues. Gene expression levels varied distinctly across different GIT segments and between young and mature subjects. The differences between calves and adults were particularly pronounced in areas such as the forestomachs, ileum, and jejunum, indicating potential changes in peptides regulating food intake based on the developmental phase. In mature individuals, the forestomachs predominantly displayed an increase in GHRL expression, while the intestines had elevated levels of GHSR, GPR173, LEP, and NUCB2. In contrast, the forestomachs in calves showed upregulated expressions of LEP, LEPR, and NUCB2, highlighting the potential importance of peptides from these genes in bovine forestomach development.

WPŁYW RODZAJU PREPARATU MLEKOZAST ˛EPCZEGO NA WYNIKI ODCHOWU CIEL ˛AT ORAZ WSKAZNIKI HEMATOLOGICZNE I BIOCHEMICZNE KRWI

The aim of this study was to evaluate the effect of the type of milk replacer on the production results of calf rearing and hematological and biochemical parameters of their blood. Calves (heifers) of the Polish Holstein-Friesian breed, divided into two groups of 18 animals each, were maintained and fed equally, except for milk replacers used from the 31st to the 90th day of calf life. Group A received milk replacer based on skimmed milk powder, and group B received milk replacer based on whey powder. Production parameters were calculated and hematological and biochemical blood indices were determined. Better calf rearing results were found when the formula A was used. Calves, despite a lower initial weight at 30 days of age, reached a higher final weight at 90 days of rearing. There was a significantly higher number of leukocytes and erythrocytes in the blood of gorup A clves, whereas in group B there was a higher average red blood cell volume and average weight of hemoglobin in a red blood cell. In addition, there were significant differences in the levels of total cholesterol and HDL cholesterol in the blood of calves fed different milk replacers (P ≤ 0.05).

WPŁYW GENOTYPU I PŁCI NA WARTOŚĆ RZEŹNĄ MŁODEGO BYDŁA OPASOWEGO SKUPOWANEGO PRZEZ JEDEN Z KRAJOWYCH ZAKŁADÓW PRZEMYSŁU MIĘSNEGO

The quality of beef is determined, among others, by factors such as breed, age and sex of slaughtered animals and fattening intensity. The aim of the study was to assess carcass quality of young cattle purchased by a selected domestic meat processing plant. The study included a group of 300 bulls and 300 heifers with selected genotypes (Limousine breed; crossbreds – Charolaise, Limousine, Simental × Polish Holstein-Friesian; Polish Holstein-Friesian breed). The following were determined for each animal: body weight before slaughter (kg), hot carcass weight (kg), hot carcass quality index (%), carcass conformation class and carcass fatness class according to the EUROP system. The mean body weight of slaughtered animals was found to be 650 kg. Carcass yield of the assessed young cattle was on average 54%. Carcasses of bulls (non-castrated males) were on aver- age 90 kg heavier and had 3 pp. higher carcass yield than carcasses of uncalved females (P < 0.05). The conformation classes of the EUROP system showed that almost 48% of the carcasses of young Limousine bulls reached the highest classes, i.e. E− and U. Limousine bulls (57.2%) had the highest carcass yield among the determined genotypic groups. The desired lowest degree of fatness was found in carcasses of bulls of all genotypes (an average of 2.9 points).

The Effect of Cow Breed and Wild Garlic Leaves (Allium ursinum L.) on the Sensory Quality, Volatile Compounds, and Physical Properties of Unripened Soft Rennet-Curd Cheese.

The aim of this study was to investigate the effects of cow breed and the addition of wild garlic on the sensory quality, volatile compounds, and physical properties of soft rennet-curd cheese. Cheese was produced from the milk of the Polish Holstein-Friesian breed Black-and-White type and the Polish Red breed, with or without the addition of wild garlic leaves. The samples were analyzed for their sensory quality, volatile compounds (using an electronic nose and GC/MS), color, and texture. The intensity of taste and smell characteristics depended only on the addition of wild garlic. PCA showed that the differences in volatile profiles resulted both from the milk cow breed and the use of wild garlic. Breed influenced almost all color parameters, while the addition of wild garlic affected all of them. The milk source, wild garlic addition, and storage duration influenced the majority of the textural parameters of the cheeses. The research conducted indicates that the addition of wild garlic leaves results in the enrichment of the volatile compound profile of cheese, making its taste and smell less milky and sour (p ≤ 0.001), while modifying its color and some textural properties (p ≤ 0.001); while, at the same time, not adversely affecting the sensory assessment of the color, appearance, texture, smell, or taste of the cheese (p > 0.05).

Influence of various chilling methods on the sustainable beef production based on high voltage electrical stimulation.

Among the challenges of sustainable management of meat production, the key issue is to improve the energy efficiency of production processes, which will consequently affect the reduction of greenhouse gas emissions. Such effects are achieved by combining various chilling systems with electrical stimulation that determines the quality of meat at the slaughter stage. The novelties of the research undertaken included determining the impact of various variants of meat production (chilling method: slow, fast, accelerated + HVES/NES) on changes in the basic (industrial) quality indicators (pH and temperature) of beef produced from Polish Holstein-Friesian breed cattle, and then indicating the optimal variant for energy-efficient (sustainable) beef production. The HVES and the fast chilling method yielded positive economic (meat weight loss), technological (high quality, hot-boning), energetic (lower electricity consumption), and organizational effects (reduced chilling and storage surfaces and expenditures for staff wages) compared to the slow and accelerated methods. Reaching the desired final temperature with an increased amount of chilled meat enables obtaining a few-fold decrease in the specific energy consumption and a higher energy efficiency of the process. This allows recommending the above actions to be undertaken by entrepreneurs in the pursuit of sustainable meat production.

New composite traits for joint improvement of milk and fertility trait in Holstein dairy cow.

ObjectiveThe objective of this study was to define a new composite trait for Holstein dairy cows and evaluate the possibility of joint improvement in milk and fertility traits.MethodsA data set consisting 35,882 fertility related records (days open [DO], calving interval [CI], and number of services per conception [NSC], and total milk yield in each lactation [TMY]) was collected from 1998 to 2016 in Polish Holstein-Friesian breed herds. In this study TMY, DO, CI, and lactation length of each cow was used to obtain composite milk and fertility traits (CMF).ResultsModerate heritability (0.15) was estimated for composite trait that was higher than heritability of female fertility related traits: DO 0.047, CI 0.042, and NSC 0.014, and slightly lower than heritability of TMY 0.19. Favourable genetic correlations (−0.87) were estimated between CMF with TMY. Spearman rank correlation coefficients between breeding value of CMF with DO, CI, and TMY were high (>0.94) but with NSC were moderate (0.64). Selection on CMF caused favourable correlated genetic gains for DO, CI, and TMY. Different selection indices with different emphasis on fertility and milk production were constructed. The amount of correlated genetic gains obtained for DO and total milk production according to selection in CMF were higher than of genetic gains obtained for DO and TMY in selection indices with different emphasis on milk and fertility.ConclusionThe animal selection only based on a composite trait - CMF proposed in current study would simultaneously lead to favourable genetic gains for both milk and fertility related traits. In this situation CMF introduced in current study can be used to overcome to limitations of selection index and CMF could be useful for countries that have problems in recording traits, especially functional traits.

WARTOŚĆ WSKAŹNIKA TB1 W MLEKU W ZALEŻNOŚCI OD KONDYCJI CIAŁA KRÓW MLECZNYCH W PIERWSZYM MIESIĄCU LAKTACJI

The research was performed on 100 cows of Black and White Polish Holstein-Friesian breed. The studied cows were under a visual and tactile evaluation of body condition using a BCS (Body Condition Scoring) method performed on the day of parturition as well as 30th day of lactation. The observation results of the body condition changes during that period were juxtaposed with FPR. The value of that indicator was determined on the base of control milking performed on the 30th day of lactation. The aim of the research was defining the relationship between the value of FPR and the changes of cows’ body condition between the day of parturition and 30th day of lactation. The statistically significant differences (P < 0.05) of FPR value in dependence of the changes in cows’ body condition between the parturition day and 30th day of lactation were determined.

Effect of Breed on the Level of the Nutritional and Health-Promoting Quality of Semimembranosus Muscle in Purebred and Crossbred Bulls.

Simple SummaryBeef is an important natural source of nutrients as well as of bioactive ingredients that improve our health. It is an excellent source of alanine, creatine, carnosine, anserine, and polyunsaturated fatty acid (PUFA), which plays an important preventative role in carcinogenic processes. The strategy for rearing and feeding cattle for slaughter should be directed at reducing saturated fatty acid (SFA) in beef fat and/or increasing PUFA, especially n-3. Therefore, the aim of the study was to determine the influence of breed types on the nutritional and pro-health quality of beef. The experiment was conducted in Poland, on 62 bulls from three breeds: Limousin, Polish Holstein-Friesian, and Polish Holstein-Friesian × Limousin. Bulls were slaughtered at 21–23 months of age, and samples of semimembranosus muscle (300 g) were cut parallel to the muscle axis at 24 h postmortem. It can be concluded that commodity crossbreeding significantly improved the quality of beef, resulting in similar or even better results than purebred cattle.Meat from commercial breed cattle are very often used to crossbreed with dairy breeds. The effect of heterosis is most evident when crossbreeds are genetically different from each other. Therefore, the aim of the study was to determine the influence of breed types on the nutritional and pro-health quality of beef. The experiment was conducted on 62 bulls from three breeds: Limousin, Polish Holstein-Friesian, and Polish Holstein-Friesian (PHF) × Limousin. During the fattening period, the animals were fed ad libitum using the same diet. Bulls were slaughtered at 21–23 months of age. The meat of PHF × Limousin hybrids was characterized by the lowest level of SFA and the highest content of n-3 PUFA fatty acids, carnosine, and α-tocopherol compared to the values obtained for the Polish Holstein-Friesian and Limousin breeds. In the case of PHF × Limousin hybrids, there was a 6% increase in n-3 PUFA, 21% in carnosine, and 66% in α-tocopherol compared to the Polish Holstein-Friesian breed. Commodity crossbreeding significantly improved the quality of beef analyzed in this study, resulting in similar or even better results than purebred cattle. This meant that beef from the hybrids with PHF was of the best nutritional and health-promoting quality.

Effects of additional colostrum feeding on the levels of protein fractions in calves’ serum

The aim of this study was to investigate the impact of additional colostrum feeding to new born calves on levels of selected serum protein fractions. The study was conducted on a commercial dairy farm. Twenty-four cows of Polish Holstein-Friesian breed and their calves were included in the trial. Chemical composition, the somatic cell count (SCC), the total bacteria count (TBC) and immunoglobulin G (IgG) concentration were determined in colostrum samples. Blood was collected via jugular vein puncture from a total of 24 calves at the 36th hour of life. Total serum protein (TSP), as well as its fractions (albumins, globulins) and IgG concentration were determined. Greater IgG, total protein, albumins and globulins concentrations were found in serum of calves fed colostrum four times compared with three times on the first day of life. It was concluded that increasing the number of colostrum feedings to four times can be beneficial to forming of passive immunity of newborn calves.

The impact of installation of automatic milking system on production and reproduction traits of dairy cows.

The objective of the research was the evaluation of change in the traditional milking system using automatic milking system in the scope of the selected reproduction features of dairy cows of the Polish Holstein-Friesian breed. Animal material consisted of 2,818 cows used on nine farms equipped with the automatic milking system Astronaut A4 made by Lely. The cows were controlled in the scope of services per conception, service period, length of pregnancy, calving interval and calving to conception period, milk yield, protein and fat content obtained in lactations of 305days. The selected traits were observed between 2005 and 2015. In this period, the milking system was changed from the conventional to automated one. The collected data material was statistically processed, using the multifactorial analysis of variance. The period between the first calving and the second effective insemination was reduced by 11.8days, and the period between the second calving and the third effective insemination was shortened by 4days after the installation of the automatic milking system. The increase in milk yield by 466kg during 305-day lactation was observed among primiparous cows. The percentage of protein and fat content in the researched groups decreased; moreover, the fall of intergroup variability was noticeable, which may be a sign of the levelling of the yield within the herd.

Effect of ageing on the physicochemical properties of musculus longissimus lumborum of young bulls of five breeds

Recent years have seen increasing interest in the conservation and use of native breeds of livestock raised in traditional farming systems. The experience of many European countries shows that promotion of raw materials and products derived from these breeds through a labelling system has a beneficial effect on the sustainable development of rural areas, contributes to preservation of the cultural heritage of the countryside, and increases the population of the breeds. As yet no beef produced in Poland has been included on the European list of traditional and regional products. For this reason we conducted a study to evaluate selected physicochemical properties of the meat of young bulls of three native breeds, Polish Red, White-Backed and Polish Black-and- White, compared with the meat of young Simmental and Polish Holstein-Friesian bulls, during a 14-day ageing of vacuum-packed meat. The following parameters were measured in m. longissimus lumborum (MLL) taken from half carcasses of 50 young bulls (10 from each breed): pH, electrical conductivity (45 min., 24 h, 2, 7 and 14 days post mortem), colour (according to CIE L*a*b*), shear force and energy. The water-holding capacity of the meat (drip loss, cooking loss and free water by the Grau-Hamm method), TBARS value (on days 2, 7 and 14) and content of haem pigments were determined as well. The physicochemical parameters of the MLL muscle obtained from the native Polish breeds of bulls (Polish Red, White-Backed and Polish Black-and-White) had intermediate values between those of Polish Holstein- Friesian (dairy type) and Simmental (dual-purpose) cattle. No qualitative deviations, such as those associated with DFD syndrome (pH 48 h in the range of 5.51-5.72), were found in any of the samples, which indicates that the raw material is well suited to the production of beef for culinary purposes. The breed of cattle was found to significantly influence the water-holding capacity parameters. The highest (P < 0.001) drip loss was reported on the 14th day post mortem for the MLL of young bulls of the Simmental (6.89%) and Polish Red breeds (6.47%). The highest cooking loss was found on the 7th day post mortem in the MLL of young bulls of the Polish Holstein-Friesian (30.66%) and Simmental breeds (30.92%). Significantly (P < 0.01) the least favourable water-holding capacity (the largest amount of free water) was shown by the muscle of young bulls of the Simmental breed on the 2nd day post mortem (75.31 mg) and the Polish Red breed on the 7th and 14th days post mortem (67.42 mg and 60.36 mg, respectively). On the 2nd and 7th days post mortem, the most tender MLL muscle was found (according to WBSF shear force) in the Polish Holstein-Friesian (76.8 N and 69.3 N) and Polish Black-and-White breeds (89.5 N and 59.1 N). On the last, 14th day of ageing, the instrumental WBSF shear force for the breeds evaluated was definitely more homogeneous and did not differ significantly (shear force in the range of 56.3-65.7 N; P > 0.05). Compared to the muscle of native breeds, that of the Polish Holstein-Friesians showed significantly lower haem pigments (on average 35 ppm less; P < 0.01) and a lower proportion of redness (a*) (P < 0.01) on the 2nd and 7th days post mortem. The MLL muscle of young bulls of the Polish Red breed had the lowest (P < 0.01) percentage content of yellowness (b*) during the whole ageing period. Significantly (P < 0.01) lower oxidative stability (higher TBARS value) was found in the meat from young bulls of the Polish Holstein-Friesian breed (on the 2nd and 7th days post mortem) and the White-Backed breed (on the 14th day) compared to all other breeds analysed. In general, the ageing time had a positive influence on the muscle quality, as the determinants of the visual and sensory attractiveness of the meat, which are also important in the meat industry, remained stable (pH), improved (colour and water-holding capacity G-H) or became more similar among the breeds (tenderness assessed on the basis of shear force, cooking loss)....

Comparison of Fatty Acid Composition of Milk from Simmental and Polish Holstein-Friesian Cows in Different Production Seasons

Abstract The aim of this study was to determine the fatty acid (FA) profile of Simmental cow milk in relation to lipid intake in feeds and their composition, and to compare it with FA composition of milk from cows of Polish Holstein-Friesian (PHF) breed. To this end, 104 milk samples were collected from Simmental cows and 52 milk samples derived from PHF breed were taken over a 2-year period. The season significantly influenced both contents of lipid, dry matter and crude protein as well as FA content in lipids extracted from forages. Winter and autumn seasons were characterized by a significantly higher intake of lipids with forages resulting from the intake of fresh silages, compared with the other seasons when the animals were fed stored silages. This was reflected in the highest content of conjugated linoleic acid (CLA) c-9 t-11 C18:2 in milk from the autumn season. Compared with PHF, milk from Simmentals had a higher content of short-chain saturated FAs (SCSFAs) and was characterized by great differences in FA contents determined in the group of odd- and branched-chain FAs (OBCFAs). Milk from Simmental cows had the butyric acid C4:0 and iso C15:0 content of 4.99 and 1.20 g/100 g FA on average, respectively, which have been associated with benefits for human health.

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.

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.

Slaughter Value of Young Polish Black-and-White, White-Backed, Polish Holstein-Friesian and Limousin Bulls Under Semi-Intensive Fattening

Slaughter Value of Young Polish Black-and-White, White-Backed, Polish Holstein-Friesian and Limousin Bulls Under Semi-Intensive FatteningThe objective of the present study was to compare the slaughter value of young bulls of two breeds included in the genetic resources conservation programme, namely Polish Black-White and White-backed with young Polish Holstein-Friesian (dairy type) and Limousin (beef type) bulls. This is the first study to evaluate the meat performance traits of White-backed cattle in several-centuries history of the breed in Poland. It was determined that populations of White-backed and Polish Black-and-White cattle represent the dual-purpose type desirable in the genetic resources conservation programme. The indices obtained for the analysed traits of slaughter value from young Polish Black-and-White and White-backed bulls were intermediate between Polish Holstein-Friesian (dairy type) and Limousin (beef type), but closer to those of the Polish Holstein-Friesian breed. The analysed muscles of young bulls had a very similar content of basic chemical components. The relatively high amount of proteins (22.85-23.23%) in musculus longissimus lumborum and in musculus semintendinosus (22.43-23.06%) should be emphasized.