The aim of the study was to determine the changes in composition and physicochemical features (pH, density, thermostability and acidity) of mare colostrum and milk, and of protein fraction contribution (serum albumin, β-casein, γ-casein, α-lactalbumin, G class immunoglobulins) depending on lactation stage. The research material was colostrum and milk samples from 12 Arabian mares. Colostrum samples were collected within 2 h after parturition and milk samples were collected twice, in the 3rd and 6th weeks of lactation. The level of basic milk components decreased significantly (only lactose content increased) as compared to colostrum. Total bacteria count and somatic cell count decreased significantly with an increase in resistance and urea level. The changes observed were connected to differentiated contribution of particular protein fractions and their relative proportions. Lower levels of γ-casein (P ≤ 0.05), β-casein, serum albumin as well as α-lactalbumin were observed in colostrum as compared to those in milk. Any relationship between lactation stage and β-casein content was observed. Serum albumin and α-lactalbumin content increased in subsequent milkings. The level of G class immunoglobulins decreased significantly and its highest level was noted in colostrum. Any significant differences between the 3rd and 6th lactation weeks were obtained.

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The objective of the study was to evaluate the effect of energy contents in a dry period diets in "7+1" feeding strategy of dry cow including 7 weeks of the dry period (far-off) and 1 week of a close-up period, on colostrum quality and the immune status of calves. Forty Holstein multiparous cows were dried at 56d before the expected date of calving and were assigned to the higher energy diet group (HE; 0.69 UFL/kg DM, NDF 52% DM), or the lower energy diet group (LE; 0.61 UFL/1kg DM, NDF 56% DM). From -7d to the expected calving date up to 21 d of lactation, all cows were fed the same fresh, lactation diet. Samples of colostrum were collected within 2h after parturition and its density, dry matter content and concentrations of immunoglobulins, fat, protein, lactose, urea and somatic cell counts were measured. Calves were weighed 2 h after calving and on the 21d of life. On 3d and 21d of calves' life blood samples were collected and the concentration of IgG, IgA, IgM, insulin-like growth factor 1 (IGF-1) as well as total protein and albumin concentrations were determined. Treatments had no significant effect on composition of colostrum and serum immunoglobulins and IGF-1 concentration. In both groups the weight of calves at birth was similar, still daily body weight gain during 21 day of rearing period in HE group was higher than in the LE group (P=0.05).

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In vitro ruminal fluid fermentation as influenced by corn-derived dried distillers' grains with solubles. Folia Biologica (Kraków) 62: 345-351. This study was conducted to evaluate changes to in vitro ruminal fluid fermentation due to the use of corn-derived dried distillers' grains with solubles (corn DDGS) as a partial or complete replacement for crushed cereal and oilseed meals in the fermentation substrate. The control substrate consisted of mixed cereal and oilseed meals (barley, wheat, soybean and rapeseed), while the experimental substrates were the same meals with increasing portions replaced with corn DDGS. Including corn DDGS decreased the total VFA concentration (P<0.05), ammonia level (P<0.001), methane emission (P<0.05) and total gas production (P<0.001) during microbial fermentation. Using DDGS-containing substrates did not change the proportions of acetate, propionate and butyrate, but did decrease the proportions of isobutyrate and isovalerate (P<0.001). The fermentation efficiency, VFA utilization index, cell yield coefficient and pH of the ruminal fluid also remained unchanged. The partial replacement of cereal and oilseed meals with corn DDGS had no deleterious effects on ruminal fluid fermentation.