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Number of results: 5
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Abstract

The aim of this research was to determine rumination time (RT) and the subsequent milk yield, along with trait changes during lactation dependent on the reproductive status of dairy cows. 728 cows were selected for evaluation in regards to 1–150 days of milk production (DIM). According to their period of lactation and reproductive status, the cows were selected for the following groups: Inseminated (1–35 days after insemination, n=182), Open (45–90 days after calving, n=126), Fresh (1–44 days after calving, n=45); Not-pregnant (>35–60 days after inse- mination and not-pregnant, n=55); Pregnant (35–60 days after insemination and pregnant (n=320). The animals were milked with Lely Astronaut® A3 milking robots. The daily milk yield, rumination time, bodyweight, milk composition (fat, protein, lactose, somatic cell count and gynecological status date) were collected from the Lely T4C management program for analysis. We estimated the lowest productivity in the pregnant cows, where the average milk yield was 28.72 kg and the highest productivity in the fresh cow (p<0.001) (Table 1). The longest rumina- tion time was determined for the inseminated cows, statistically significantly higher at 9.92% (p<0.001) than in the non-pregnant cows, whose rumination time was the shortest. The statisti- cally reliably RT positively correlated with productivity (r=0.384, p<0.001) of the cows (from r=0.302 in the second lactation and r=0.471 in the first lactation to r=0.561 in multiparous cows; p<0.001). Rumination time, according to groups of cows by milk yield, had a tendency to increase (2.14 times) from 202.0± 87.38 (in cows with a productivity of less than 10 kg milk) to 431.6±33.91 (in cows with a milk yield higher than 50 kg) by the linear regression equation: y = 38.02x + 232, R² = 0.721 (p<0.001). The relation between the gynecological status and milk fat-protein ratio of the cows was statistically significant (χ2=2.974, df= 8, p <0.0001). The longest rumination time was determined for the inseminated cows (1 – 35 days after insemination), and the shortest for the not-pregnant cows (>35 – 60 days after insemination and not-pregnant). We can conclude that rumination time, subsequent yield, and milk trait change depends on the period of lactation and reproductive status of a dairy cow.
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Abstract

This study investigated changes in the real-time measured levels of milk β-hydroxybutyrate according milk yield, lactation number and status of reproduction in dairy cows. A total of 378 cows were selected. According to their reproductive status the cows were classified as belonging to the following groups: Fresh (1 – 44 days after calving. n=43). Open (45 – 65 days after calving. n=78), Inseminated (1 – 35 days after insemination. n=133). Pregnant (35 – 60 days after insemination and pregnant (relatively pregnant) (n=124). The cows were milked with DeLaval milking robot (DeLaval Inc., Tumba, Sweden) in combination with a Herd Navigator (Lattec I/S. Hillerød. Denmark) analyser. We observed that milk β-hydroxybutyrate (BHB) had a tendency of increasing with an increase of lactation number. The average BHB in multiparous cows was 11.111% higher in comparison with primiparous cows (p<0.001). We found higher BHB concentration in the multiparous cows in all reproduction status groups (p<0.001). A strong positive statistically significant (p<0.001) relationship has been found between BHB and the average milk yield within all groups of primiparous cows although we found a statistically unreliable coefficient of correlation (from -0.202 to 0.057) between highest milk yield and BHB in primiparous and multiparous cows.
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Abstract

Tonnacypris glacialis (G.O. Sars, 1890) is a meiobenthic species widely distributed in Arctic freshwater lakes. Field study of its life cycle as well as the laboratory experiments showed clearly that only one generation of this ostracod species occurs during the vegetation season, and that the condition necessary for the next generation to appear is eggs freezing.
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Abstract

Our macroscopic observations and microscopic studies conducted by means of a light microscope (LM) and transmission electron microscope (TEM) concerning the reproduction biology of Colobanthus quitensis (Caryophyllaceae) growing in natural conditions in the Antarctic and in a greenhouse in Olsztyn (northern Poland) showed that this plant develops two types of bisexual flowers: opening, chasmogamous flowers and closed, cleistogamous ones. Cleistogamy was caused by a low temperature, high air humidity and strong wind. A small number of microspores differentiated in the microsporangia of C. quitensis , which is typical of cleistogamous species. Microsporocytes, and later micro − spores, formed very thick callose walls. More than twenty spheroidal, polypantoporate pollen grains differentiated in the microsporangium. They germinated on the surface of receptive cells on the dry stigma of the gynoecium or inside the microsporangium. A monosporic embryo sac of the Polygonum type differentiated in the crassinucellar ovule. During this differentiation the nucellus tissue formed and stored reserve materials. In the development of generative cells, a male germ unit (MGU) with differentiated sperm cells was observed. The smaller cell contained mainly mitochondria, and the bigger one plastids. In the process of fertilization in C. quitensis only one nucleus of the sperm cell, without cytoplasm fragments, entered the egg cell, and the proembryo developed according to the Caryophyllad type. Almost all C. quitensis ovules developed and formed perispermic seeds with a completely differentiated embryo both under natural conditions in the Antarctic and in a greenhouse in Olsztyn.
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Abstract

The authors report the first discovery of diploid populations of Hieracium naegelianum Panč. subsp. naegelianum and H. naegelianum subsp. ljubotenicum Behr & Zahn., and give the first chromosome counts for H. cernuum Friv., H. gymnocephalum Griseb. ex Pant., H. sparsum Friv., Pilosella pavichii (Heuff.) Holub and P. serbica (F. W. Schultz & Schultz-Bip.) Szeląg from Macedonia and/or Montenegro. A diploid chromosome count for Hieracium renatae Szeląg is confirmed based on material from the whole distribution range of the species. An emasculation experiment showed that all the analyzed diploid Hieracium taxa reproduce sexually.
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