Changes in fatty acid profile and iodine content in milk as influenced by the inclusion of extruded rapeseed cake in the diet of dairy cows

The aim of the study was to evaluate the effect of extruded rapeseed cake in diets of dairy cows on changes in milk fatty acid profile and iodine content in milk and on the thyroid gland status. An experiment was carried out on four lactating Holstein cows divided into 2 groups - experimental (R) fed a diet based on extruded rapeseed cake and control (S) fed a diet based on extruded full-fat soya. The experiment was divided into 4 periods of 42 days (21 days of preliminary period and 21 days of experimental period). Samples of milk and blood were taken three times a week during the experimental period. DMI was not affected by the treatment (P > 0.05). Milk yield and 4% FCM were lower in R compared to S (P 0.05). However, the content of MUFA in R was higher (34.71 g/100 g) and the content of PUFA was lower (4.00 g/100 g) than in S (32.14 and 5.54 g/100 g, respectively (P 0.05). The mean daily intake of glucosinolates (Gls) in R was 50.14 mmol and resulted in a significant decrease in iodine concentration in milk in R (196.7 mu g/l) in comparison with S (367.0 mu g/l, P 0.05)

RISK CAUSED BY NATURAL OCCURRENCE OF DEOXYNIVALENOL IN FEED FOR COWS

The aim of the study was to predict the transfer of mycotoxin deoxynivalenol (DON) from naturally contaminated feedstuffs to cows´ milk under on-farm conditions. The experiment was carried out in a private farm on 10 lactating Czech Fleckvieh x Holstein cows. The experiment lasted 14 days and was divided into an adaptation (11 d) and collection periods (3 d). The cows were fed individually twice a day and the diet consisted of corn silage, haylage, meadow hay and a supplemental mixture. Bulky feeds were produced from own-grown forages that were not treated against the fungi. Feed intake and milk yield was monitored daily. Samples of individual feedstuffs were analysed on the content of basic nutrients and DON. Milk was analysed on basic constituents. From the obtained results, dry matter (DM) and DON intakes were calculated. Content of DON in milk was predicted using carry-over rates of 0.0001 % and 0.0024 % available in the literature. All feedstuffs were naturally contaminated with DON. The highest concentration was found in corn silage, 389 μg/kg DM, and the lowest in hay and haylage, 15 μg/kg DM. The average daily intake of DON was 3515.3 μg/day. The predicted concentration of DON in milk ranged between 0.00018 and 0.00422 μg/l

Alternative and Unconventional Feeds in Dairy Diets and Their Effect on Fatty Acid Profile and Health Properties of Milk Fat

Milk fat is an important nutritional compound in the human diet. From the health point of view, some fatty acids (FAs), particularly long-chain PUFAs such as EPA and DHA, have been at the forefront of interest due to their antibacterial, antiviral, anti-inflammatory, and anti-tumor properties, which play a positive role in the prevention of cardiovascular diseases (CVD), as well as linoleic and γ-linolenic acids, which play an important role in CVD treatment as essential components of phospholipids in the mitochondria of cell membranes. Thus, the modification of the FA profile—especially an increase in the concentration of polyunsaturated FAs and n-3 FAs in bovine milk fat—is desirable. The most effective way to achieve this goal is via dietary manipulations. The effects of various strategies in dairy nutrition have been thoroughly investigated; however, there are some alternative or unconventional feedstuffs that are often used for purposes other than basic feeding or modifying the fatty acid profiles of milk, such as tanniferous plants, herbs and spices, and algae. The use of these foods in dairy diets and their effects on milk fatty acid profile are reviewed in this article. The contents of selected individual FAs (atherogenic, rumenic, linoleic, α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and their combinations; the contents of n3 and n6 FAs; n6/n3 ratios; and atherogenic, health-promoting and S/P indices were used as criteria for assessing the effect of these feeds on the health properties of milk fat

Effect of Ruminally-protected leucine supplement on milk yield and plasma amino acids in dairy cows

The aim of this study was to determine the influence of leucine supplement in the form of rumen-protected tablets on milk yield and composition and plasma amino acids in four high-yielding lactating Holstein cows. The experiment was carried out as a cross-over procedure and was divided into 4 periods of 14 d (10 d preliminary period and 4 d experimental period). Cows were fed ad libitum a diet based on maize silage, lucerne hay and a supplemental mixture. The diet, defficient in methionine, lysine, and leucine, was supplemented with methionine+lysine (Control) or methionine+lysine+leucine (Leu) in rumen protected form. The dry matter intake, milk yield and milk yield expressed in energy corrected milk did not differ significantly between the treatments. Milk protein content and yield did not show statistically significant variation. The contents and yield of casein, fat, lactose and urea were unaffected by the treatment. Blood metabolites did not vary between the treatments. The introduction of Leu resulted in higher plasma levels of proline (p<0.05) in comparison to Control. The calculated leucine defficiency in maize silage-concentrate diet used in the present experiment was approx 5.5%. The results of this experiment suggest that under the given conditions, leucine was not a limiting amino acid.vo