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.

2019

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Abstract

Pastures are botanically diverse and difficult to characterize. Digital modeling of pasture biomass and quality by non-destructive methods can provide highly valuable support for decision-making. This study aimed to evaluate aerial and on-ground methods to characterize grass ley fields, estimating plant height, biomass and volume, using digital grass models. Two fields were sampled, one timothy-dominant and the other ryegrass-dominant. Both sensing systems allowed estimation of biomass, volume and plant height, which were compared with ground truth, also taking into consideration basic economical aspects. To obtain ground-truth data for validation, 10 plots of 1 m2 were manually and destructively sampled on each field. The studied systems differed in data resolution, thus in estimation capability. There was a reasonably good agreement between the UAV-based, the RGB-D-based estimates and the manual height measurements on both fields. RGB-D-based estimation correlated well with ground truth of plant height (R 2 > 0.80) for both fields, and with dry biomass (R 2 = 0.88), only for the timothy field. RGB-D-based estimation of plant volume for ryegrass showed a high agreement (R 2 = 0.87). The UAV-based system showed a weaker estimation capability for plant height and dry biomass (R 2 < 0.6). UAV-systems are more affordable, easier to operate and can cover a larger surface. On-ground techniques with RGB-D cameras can produce highly detailed models, but with more variable results than UAV-based models. On-ground RGB-D data can be effectively analysed with open source software, which is a cost reduction advantage, compared with aerial image analysis. Since the resolution for agricultural operations does not need fine identification the end-details of the grass plants, the use of aerial platforms could result a better option in grasslands.

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Abstract

In this study, a brown macroalgae species, Saccharina latissima, processed to increase its protein concentration, and a red macroalgae species, Porphyra spp., were used to evaluate their in vivo digestibility, rumen fermentation and blood amino acid concentrations. Four castrated rams were used, whose diets were supplemented with a protein-rich fraction of S. latissima, a commercial Porphyra spp. and soybean meal (SBM). Our results show that the protein digestibility of a diet with S. latissima extract was lower (0.55) than those with Porphyra spp. (0.64) and SBM (0.66). In spite of the higher nitrogen (N) intake of diets containing Porphyra spp. and SBM (20.9 and 19.8 g N/day, respectively) than that with S. latissima (18.6 g N/day), the ratio of N excreted in faeces to total N intake was significantly higher in the diet with S. latissima than those with Porphyra spp. and SBM. This reflects that the utilization of protein in S. latissima was impaired, possibly due to reduced microbial activity. The latter statement is corroborated by lower volatile fatty acid composition (25.6, 54.8 and 100 mmol/l for S. latissima, Porphyra spp. and SBM, respectively) and a non-significant tendency for lower ammonia concentration observed in diets with S. latissima and Porphyra spp. compared to SBM. It is important to note that the S. latissima used in this trial was rinsed during processing to remove salt. This process potentially also removes other water-soluble compounds, such as free amino acids, and may have increased the relative fraction of protein resistant to rumen degradation and intestinal absorption. Furthermore, the phlorotannins present in macroalgae may have formed complexes with protein and fibre, further limiting their degradability in rumen and absorption in small intestines. We recommend that further studies explore the extent to which processing of macroalgae affects its nutritive properties and rumen degradability, in addition to studies to measure the intestinal absorption of these macroalgae species

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Abstract

With increasing intensification of the dairy sector in many countries and with the introduction of automatic milking, exercise paddocks combined with full indoor feeding, as an alternative to production pasture, are being used as a compromise between farm economics and cow welfare. This study examined whether there are production benefits for high-producing dairy cows in an alternative system that uses pasture at a level of approximately 50% of the total roughage intake in the diet. In an automatic milking system with 12-h night access to the outdoor environment, we compared milk production and behavior of cows in 2 systems: an exercise paddock combined with ad libitum grass silage indoor feeding and a production pasture combined with a restricted daytime grass silage ration. There were 20 cows in the former and 21 cows in the latter system, with the treatments running in parallel. The experiment started in late June with no complete darkness during the night, and lasted for 12 wk, with 5.6 h of darkness at the end. We therefore also explored the effect of night length on milk production and behavior parameters. All cows showed strong motivation for going outdoors and grazing when pasture access was given in early evening, but after a few hours both groups went to the barn and did not return to the pasture area during the remaining night. As the season progressed and nights became longer, cows on the exercise paddock treatment reduced time spent outdoors and grazing time, whereas they increased time spent resting outdoors. The group on exercise paddock had a greater milk yield (kg of milk) over the experimental period than the production pasture group. The latter group also showed a greater drop in milk yield over the duration of the trial. Thus, for cows milked in an automatic milking system and offered nighttime outdoor access, no milk production benefits were observed in offering production pasture with restricted indoor silage allowance instead of an exercise paddock with ad libitum silage. We therefore suggest that automatic milking farmers with similar production levels and automatic milking-management systems as in the present experiment, who wish to in-clude grazed grass as part of the dairy cow diet, should ensure that cows have pasture access in the afternoon and evening.