Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2007
Abstract
A main scourge in Norwegian sheep farming is tick-borne fever (TBF) caused by the bacteria A. phagocytophilum and transmitted by the tick Ixodes ricinus. The aim of this poster is to present a new research project on resistance to TBF in sheep (2007?2010).
2006
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Organic farming movements have traditionally aimed at a harmonious balance between animal husbandry and crop production on the farm. We bring scientific evidences that this is a prerequisite to maximize the efficiency of nitrogen use. The use of imported feed increases the total nutrient losses to the environment per litre of milk produced.
Authors
Ievina Sturite Marianne Vileid Uleberg Marit Jørgensen Trond Henriksen Anne Kjersti Bakken Tor Arvid BrelandAbstract
In order to improve the basis for utilising nitrogen (N) fixed by white clover (Trifolium repens L.) in northern agriculture, we studied how defoliation stress affected the N contents of major plant organs in late autumn, N losses during the winter and N accumulation in the following spring. Plants were established from stolon cuttings and transplanted to pots that were dug into the field at Apelsvoll Research Centre (60 degrees 42'N, 10 degrees 51' E) and at Holt Research Centre (69 degrees 40' N, 18 degrees 56' E) in spring 2001 and 2002. During the first growing season, the plants were totally stripped of leaves down to the stolon basis, cut at 4 cm height or left undisturbed. The plants were sampled destructively in late autumn, early spring the second year and after 6 weeks of new spring growth. The plant material was sorted into leaves, stolons and roots. Defoliation regime did not influence the total amount of leaf N harvested during and at the end of the first growing season. However, for intensively defoliated plants, the repeated leaf removal and subsequent regrowth occurred at the expense of stolon and root development and resulted in a 61-85% reduction in the total plant N present in late autumn and a 21-59% reduction in total accumulation of plant N (plant N present in autumn + previously harvested leaf N). During the winter, the net N loss from leaf tissue (N not recovered in living nor dead leaves in the spring) ranged from 57% to 74% of the N present in living leaves in the autumn, while N stored in stolons and roots was much better conserved. However, the winter loss of stolon N from severely defoliated plants (19%) was significantly larger than from leniently defoliated (12%) and non-defoliated plants (6%). Moreover, the fraction of stolon N determined as dead in the spring was 63% for severely defoliated as compared to 14% for non-defoliated plants. Accumulation in absolute terms of new leaf N during the spring was highly correlated to total plant N in early spring (R-2 = 0.86), but the growth rates relative to plant N present in early spring were not and, consequently, were similar for all treatments. The amount of inorganic N in the soil after snowmelt and the N uptake in plant root simulator probes (PRS (TM)) during the spring were small, suggesting that microbial immobilisation, leaching and gas emissions may have been important pathways for N lost from plant tissue.
Abstract
White clover (WC, Trifolium repens L.) or red clover (RC, Trifolium pratense L.) was grown in mixture with grasses. Samples of the mixtures and pure clovers were taken during three cuts, and the fatty acids (FA) compositions were determined. The clover species had no significant effect on the individual FA contents of the leys (g kg-1 dry matter (DM)), nor on the total FA content. Pure clovers had lower content of all individual FA (8.2 vs. 12.4 g kg-1 DM) than mixtures; the contents of all FA decreased with increasing percentage of clover in the mixture, but the decrease was weaker for C18:3n-3 than for the other FA. Although pure WC and RC had similar FA contents, the relative proportions (percentage of total FA content) of C16:0 and C18:3n-3 differed; RC had a higher proportion of C18:3n-3 and a lower proportion of C16:0. These results are partly in contradiction with previously reported.
Abstract
Early stage of grass maturity increased the total concentration of fatty acids (FA) and the concentration of alpha-linolenic acid in organic ley compared to normal stage. Organic ley with red clover resulted in higher concentration of alpha-linolenic acid than white clover. Unexpectedly, increased portions of clover in the ley resulted in lower total concentration of FA. Early harvested ley with red clover may result in forage with high concentrations of alpha-linolenic acid and thus provide a good basis for milk production with a healthy composition of milk fat with a low omega-6/omega-3 FA ratio.
Abstract
Use of high energy feed supplementation can improve the protein retention by the cattle, and it has been suggested as a way to increase the nitrogen (N) effi-ciency of dairy production. However, in praxis feed supplementation is also used to increase the intensity of animal production above the level that can be supported by the farm's local plant production. A collection of published surveys showed that dairy farms that buy feed are considerably lees N efficient than farms that supply the entire animal ration from their own plant production. The total N emission to the environment per litre milk doubled when 30% of the total feed ration was produced outside the dairy farm. This was so for organic as well as conventional farms. Similar results can be expected for phosphorous and other nutrients. In order to ensure a sustainable and environmentally friendly organic production, imports of feed produced far away from the dairy farm should be strictly limited. We suggest a ceiling of 5 - 10% of total feed ration.
Abstract
The effect of clover species and level of concentrate supplementation on milk fatty acid (FA) composition has been studied. White (WC) and red clover (RC) grown in mixture with grasses were preserved in round bales and fed to autumn calving dairy cows during the first 10 weeks of lactation. Milk FA was higher in linolenic acid, vaccenic acid and rumenic acid for RC than for WC silage (0.90 vs. 0.79 %, 1.52 vs. 1.36 %, 0.90 vs. 0.75 % for these 3 FA, respectively), and RC silage gave a higher n-3/n-6 milk FA ratio than WC (0.98 vs. 0.72). Concentrate supplementation decreased the level of vaccenic acid (1.21 vs. 1.68 %), linolenic acid (0.63 vs. 1.05 %) and the n-3/n-6 ratio (0.55 vs. 1.16) as compared with no supplementation, and the effect of supplementation was similar for the two silages
Abstract
White clover (WC, Trifolium repens L.) or red clover (RC, Trifolium pratense L.) was grown in mixture with grasses. Samples of the mixtures and pure clovers were taken during three cuts, and the fatty acids (FA) compositions were determined. The clover species had no significant effect on the individual FA contents of the leys (g kg-1 dry matter (DM)), nor on the total FA content. Pure clovers had lower content of all individual FA (8.2 vs. 12.4 g kg-1 DM) than mixtures; the contents of all FA decreased with increasing percentage of clover in the mixture, but the decrease was weaker for C18:3n-3 than for the other FA. Although pure WC and RC had similar FA contents, the relative proportions (percentage of total FA content) of C16:0 and C18:3n-3 differed; RC had a higher proportion of C18:3n-3 and a lower proportion of C16:0. These results are partly in contradiction with previously reported.