Browsing by Subject "Laminaria digitata"

Iodine deficiency is a global health problem that causes physical and mental development disorders in humans. School-age children, pregnant women and consumers of organic food are particularly vulnerable to iodine deficiency. The popularity of organic products is growing, and attention should be paid to the iodine content of organic milk, as the iodine content of organic milk is usually lower than in conventionally produced milk. The aim of this study was to increase the iodine content of organic milk by adding two different species of seaweed, Ascophyllum nodosum and Laminaria digitata, to dairy cow diets, and thus create a sustainable mineral feeding strategy for dairy cows in organic production. The aim was to study the effect of dietary seaweed addition to iodine content of milk together with rapeseed cake or pea, as rapeseed cake is known to contain goitrogenic compounds that reduce iodine transfer to milk. The experiment was conducted at the Viikki Research Farm from 31 March to 25 June 2020. The experiment included 12 lactating Ayrshire cows and the experimental design was a cyclic changeover study. The factors studied were the effects of dietary protein source (rapeseed cake or pea) and the species A. nodosum or L. digitata on the intake of mineral and trace elements on dairy cows and on the mineral content of milk. In particular, effects on milk iodine were studied. The experiment had three 17-day trial periods and there was an 18-day wash-out period between the periods, when no seaweed was fed in order to minimize the carry-over effects between periods. The samples were collected on the last four days of the periods. Experiment included six dietary treatments in which protein feed was isonitrogenously either rapeseed cake or pea and diets were supplemented with seaweed. The dietary treatments were: rapeseed control K-R (no seaweed), pea control K-H (no seaweed), which were supplemented with 56,9 g dry matter (DM)/d A. nodosum i.e. seaweed 1 (M1- R, M1-H) and 7,8 g DM/d L. digitata i.e. seaweed 2 (M2-R, M2-H). The target iodine content of control diets was 1 mg/kg DM and seaweed diets 4 mg/kg DM. Finnish iodine recommendation for feeds that do not contain goitrogenic compounds is 1 mg/kg DM. Cows had ad libitum access to partial mixed ration that contained grass silage, barley and protein feed. In addition, concentrate was given to cows 1,8 kg/d and contained minerals (300 g/d), molassed sugar beet pulp, molasses and also seaweed in seaweed diets. The forage to concentrate ratio was 65:35. Mineral used in diets was approved for organic production and contained iodine 60 mg/kg DM. Dietary treatments did not affect DM intake. Compared to rapeseed diets, pea diets had a 0,15 kg/d lower crude protein intake, 0,24 kg/d lower crude fat intake and 49,7 µg/d lower iodine intake. Iodine intake increased on average by 63,4 µg when seaweed was added to the diet and the effect was greater when adding L. digitata compared to A. nodosum. Also, milk yield was lower with pea diets than with rapeseed diets. The iodine content of milk was higher with pea diets than with rapeseed diets (324 vs. 117 µg/l). Moreover, the addition of seaweed increased the iodine content of milk (on average +226 µg/l). Based on the results, iodine intake was lower with pea diets than with rapeseed diets, as expected, due to the higher iodine concentration of rapeseed cake. Both seaweeds increased the iodine content of milk, but the transfer of iodine to milk was higher with pea-based diets compared to rapeseed-based diets, due to goitrogenic compounds in the rapeseed cake.