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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.

2024

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Abstract

Floral initiation in biennial-fruiting red raspberry is controlled by the interaction of temperature and photoperiod. To determine the threshold temperatures for short day (SD) floral initiation in early- and late-flowering cultivars, we exposed plants of ‘Glen Ample’, ‘Glen Mor’ and ‘Duo’ to 12°, 16° and 20°C in a daylight phytotron under naturally decreasing autumn daylength at Ås, Norway (59°40’N). While none of the cultivars ceased growing or initiated floral primordia at 20°C, ‘Glen Ample’ and ‘Glen Mor’ initiated buds at 12° and 16°C, whereas ‘Duo’ formed flower buds at 12°C only. Surprisingly, however, all plants flowered abundantly in spring after winter chilling in the dark at −1.5 ± 0.5°C for 7 months. We discuss two possible explanations for this unusual and novel flowering response. Fractional induction is well known in raspberry, and we visualise that in SD at 20°C, the SD requirement is fulfilled, while floral induction is still blocked by inappropriate temperature. A vernalisation-like response is alternatively suggested as this can take place at near-freezing temperatures in the dark. A combination of the two mechanisms is also possible and likely. We conclude, however, that the two floral induction processes are fundamentally different and controlled by different physiological mechanisms.

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Abstract

Mushroom (Agaricus bisporus) and oyster (Pleurotus ostreatus) cultivation generates a vast amount of by-product after the harvest of edible products in the form of used compost, so called spent mushroom composts (SMC) or spent oyster substrate (SOS). In Europe, more than three million tons of SMC are produced every year as a by-product from mushroom cultivation. The management of SMC and SOS has thus become an increasing challenge from an environmental point of view. This spent material has been utilized as growing media, bio-fertilizers, in bioremediation and as a tool to control plant diseases. They have, therefore, a great potential to be implemented in primary food production. The current study investigated the impact of SMC or SOS amendment to peat on plant and microbial growth. The achieved results indicated increased flower and yield potential after SMC amendment to peat compared with SOS. Assessment of microflora in the substrate highlighted higher amount of beneficial microbial groups such as Pseudomonas, in peat and SMC mixtures compared to the ones with peat and SOS.

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Abstract

Studies have shown that extended wilting of grass before ensiling can improve the metabolizable protein (MP) value of the grass silage, both from increased rumen microbial crude protein (MCP) yield and ruminally undegraded crude protein (RUP). We hypothesised that extending the wilting of grass before ensiling can increase milk and milk protein production in dairy cows. Consequently, increased silage MP can reduce the need for MP in concentrate, estimated as amino acids absorbed in the small intestine (AAT20). To test this, a continuous feeding experiment was conducted, with 48 early- to mid-lactation Norwegian Red dairy cows. Treatments were 2 wilting levels of grass silages: 260 vs. 417 g dry matter (DM) per kg, and 2 qualities of concentrates differing in MP, in a 2 × 2 factorial arrangement (n = 12). The concentrates were low MP (LMP); 104 g AAT20/kg DM, and high MP (HMP); 123 g AAT20/kg DM, supplied at 8.75 kg DM/cow per day. The cows had ad libitum access to the grass silages. The experiment lasted for 11 weeks. The first 2 weeks, where cows received identical diets, were used as the covariate period. Those data together with data collected the last 4 weeks were used for statistical evaluation of treatments. Increasing DM concentration in silage reduced lactic acid, ammonia nitrogen and proportion of methionine in the grass silage, while it increased residual water-soluble carbohydrates, pH, proportion of aspartic acid and rumen degradability of NDF. There was no difference between treatments in daily silage DM intake (13.1 kg), milk yield (30.2 kg) or milk composition. However, feeding HMP increased urea and uric acid in urine, and urea in blood plasma, thereby reduced N efficiency. No major differences were found for rumen pH, or purine derivatives to creatinine index in urine, as indication for MCP. There was significantly more histidine in blood plasma when cows were fed HMP concentrate. In conclusion, increased DM concentration in silage and HMP concentrate did not increase milk production or milk protein yield in this study.

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Abstract

The aim of this study was to examine how silages from different grassland species and harvesting frequencies affect feed intake, milk production, and methane (CH4) emission in dairy cows. We hypothesized that cows consuming silages of more frequent harvest, grass species with greater organic matter digestibility and legumes with lower NDFom concentration would have greater silage dry matter intake and milk yield and thereby lower CH4 yield and intensity. Forty Norwegian Red cows were allocated to 5 treatments in a cyclic changeover design with 4 21-d periods (14 d of adaptation, 7 d of data collection). The 5 treatments evaluated were silages produced from timothy (Phleum pratense L.) in a 3-cut system (T3), timothy in a 2-cut system (T2), perennial ryegrass (Lolium perenne L.) in a 3-cut system (PR3), red clover (Trifolium pratense L.) in a 3-cut system (RC3) and a mix of T3 and RC3 (50:50 on DM basis) (T3/RC3). The treatments were prepared by mixing silages from each crop over the growing season, proportional to the harvested DM yield of each cut. Cows were offered the mixed silages ad libitum supplemented with a fixed level of concentrate. Gas emissions were measured using 2 Greenfeed units. Milk yield was recorded in the milking robot at each visit, and milk samples were collected at 3 consecutive milkings during the last 7 d of each period. Cows were weighed after each milking, and total-tract digestibility of each diet was estimated using acid insoluble ash as internal marker in fecal grab samples. The data were analyzed using the MIXED procedure of SAS with block, period and treatment as fixed effects and animal within block as random effect. Silage and total DMI did not differ between T3 and T2, but total DMI was lower for PR3 than for T3. There was a quadratic effect of increased proportion of red clover, with highest intakes of T3/RC3 and lower intakes of RC3 than of T3. Energy corrected milk (ECM) yield was lower for T2 than T3, and for PR3 than T3. There was a quadratic effect of increased proportion of red clover, with highest ECM yield in T3/RC3 and lower in RC3 than in T3. Organic matter digestibility was lower for T2 than T3, but it did not differ between T3 and PR3. Including red clover in the diet linearly decreased organic matter digestibility. Methane production (g/d) did not differ between T3 and T2, but CH4 intensity (g/kg ECM) was greater for T2 than for T3. There was no difference between T3 and PR3 for CH4 production but yield and intensity were greater for PR3 than T3. Including red clover in the diet linearly increased CH4 production, yield and intensity with greatest intensity in the 100% red clover diet. In conclusion, changing harvesting frequency for timothy from 2 to 3 harvests per year did not affect CH4 production or yield, but CH4 intensity was reduced. Replacing timothy with perennial ryegrass and increased inclusion rate of red clover both increased CH4 yield and intensity. Key words: enteric methane, timothy, red clover, perennial ryegrass, greenfeed system