Áhrif fituíblöndunar í fóður mjólkurkúa á nyt og efnainnihald mjólkur

Publisher´s versionThirty-seven dairy cows of the Icelandic breed were used in a change-over design experiment. The aim was to analyse the effects of moderate addition of high-palmitic acid (C16:0) fat supplement to a grass silage-based diet. There were three experimental treatments: a treatment with the fat supplement as powder (FAPOW); a treatment with the fat supplement in pelleted concentrate (FAPEL); and a control treatment (CONTROL). Milk protein content was significantly lower, and there was a tendency (p<0.10) toward a higher milk fat content in the fat treatments. This resulted in significantly higher milk fat:protein ratio in the fat treatments compared to the control (FAPOW 1.21 and FAPEL 1.20; CONTROL 1.15). A significant reduction in the ratio of casein in milk protein due to fat addition explains the reduction in milk protein. The concentration of free fatty acids in milk was higher in the fat treatments, especially FAPEL. The ratio of C16:0 in total fatty acids was increased by the fat treatments.Tilraunin sem hér er sagt frá var skipulögð þannig að 37 íslenskar mjólkurkýr voru látnar prófa þrjár fóðurmeðferðir, í mismunandi röð. Markmiðið var að greina áhrif hóflegrar fituviðbótar, aðallega á formi pálmasýru (C16:0), í fóður mjólkurkúa þar sem vothey verkað úr grasi er undirstaðan. Fóðurmeðferðirnar þrjár voru: fituviðbót á formi þurrfitu (FAPOW); fituinnblöndun í kjarnfóðurblöndu (FAPEL); og viðmiðunarfóðrun án fituviðbótar (CONTROL). Hlutfall próteins í mjólk var lægra og tilhneiging til hærra mjólkurfituhlutfalls þegar fitu var bætt í fóðrið. Þetta leiddi til marktækt hærra fitu: prótein hlutfalls í mjólkinni í fóðurmeðferðum með viðbótarfitu í samanburði við viðmið (FAPOW 1.21 og FAPEL 1.20, samanborið við CONTROL 1.15). Lækkun á hlutfalli kaseins í mjólkurpróteini vegna fituviðbótar í fóðri skýrir áðurnefnda lækkun á heildarpróteini í mjólk. Styrkur frjálsra fitusýra í mjólk var hærri þegar fitu var bætt í fóður, sérstaklega þegar það var gert í gegnum kjarnfóðurblöndu (FAPEL). Hlutfall pálmasýru af fitusýrum í mjólk var hærra þegar fitu var bætt í fóðrið.Agricultural Association of South Iceland; The Icelandic Cattle Productivity Fund; The Dairy Industry Association (SAM)Peer Reviewe

Caffeine exposure from beverages and its association with self-reported sleep duration and quality in a large sample of Icelandic adolescents

Funding Information: This work was supported by funding from the Icelandic Ministry of Industries and Innovation. The Ministry had no role in study design, data collection, data analysis, data interpretation, or reporting. Publisher Copyright: © 2021 The AuthorsPrevious risk assessments have concluded that adolescent's caffeine exposure from energy drinks (ED) are of limited concern. Recent surveys have, however, shown substantial increase in consumption. This cross-sectional survey conducted in 2020 estimated caffeine exposure from beverages among ∼80% of all 13-15-year-old adolescents (n = 10358) relative to the European Food Safety Authority's level of no safety concern of (3.0 mg/kg bw) and level for effects on sleep (1.4 mg/kg bw). Associations with self-reported sleep duration and quality were also explored. ED consumers were more likely to exceed the limit of no safety concern (prevelance: 12–14%) compared to non-ED-consumers (1–2%). Exceeding the limit for effects on sleep was also higher among ED consumers (31–38%) than non-ED-consumers (5–8%). Across categories of low (3.0 mg/kg bw) caffeine intake, the prevalence of participants sleeping <6 h increased from 3% to 24%, respectively. The corresponding adjusted Prevalence Ratio was 4.5 (95% CI: 3.6, 5.7) and mean decrease in duration of sleep was 0.74 h (95% CI: 0.65, 0.84). In conclusion, caffeine intake from beverages above the limit of no safety concern was largely confined to ED consumers. Consistent with effects from intervention studies in adults, caffeine intake was strongly associated with self-reported sleep duration in this representative population.Peer reviewe

Substrate levels, carbohydrate degradation rate and their effects on ruminal end-product formation

New feed evaluation systems for ruminants, based on dynamic-mechanistic models and predictions of production responses to nutrients, demand accurate prediction of end-products formed during rumen fermentation. The aim of the present work was to investigate the effects of levels of different substrates and carbohydrate degradation rates upon ruminal end-product formation. An in vitro method was introduced to evaluate feeds with respect to ruminal starch degradation. The method was based on incubation of feed samples in a buffered rumen fluid solution and a subsequent enzymatic analysis of remaining starch. Heat treatment generally increased rate or extent of starch degradation to glucose. Use of single time point determinations correlated reasonably well with degradation rate estimates and offers the possibility to reduce the cost of analysis. Two experiments with a 2x2x2 factorial arrangement of treatments were performed with an in vitro rumen simulation technique (SIMCO) to investigate the direct effects and interactions of several dietary factors upon ruminal fermentation. Response in volatile fatty acid (VFA) proportions to starch level was dependent on starch and neutral detergent fibre (NDF) sources. Faster degradation rates of starch and NDF had a positive effect upon microbial N efficiency and the propionate proportion. Increasing the level of N improved microbial N efficiency and increased the proportion of propionate and butyrate at the expense of acetate. Increased feeding level resulted in a lower microbial N efficiency and a lower proportion of propionate. The results of the two in vitro experiments clearly point out that rumen VFA proportions and microbial N efficiency are not only affected by the level of different substrates fermented in the rumen but also their degradation rates. Data from Nordic dairy cow experiments were analysed and modeled with respect to effects of feed characteristics upon rumen fermentation patterns. The final model differed relative to published VFA models by predicting a smaller effects of starch but large effects of silage lactate levels on propionate proportions. To improve the prediction of end-product formation, better characterization of feeds are needed. Carbohydrate degradation rate and type of forage are factors that probably should be included in future models

Evaluation of methods for estimating starch digestibility and digestion kinetics in ruminants

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