This is an interesting article and technique. I think it could be considered for application in small and large ruminant extensive grazing systems in developing countries where dry matter intake measurements are difficult. Nutritional composition of several key feed ingredients and alternatives could be analyzed and combined in these relationships to examine the proportional composition of key nutrients (e.g., NDF, CP, NSC) in predominant grazing feed sources, and related to animal needs.
It has not to my knowledge been applied in domestic ruminant grazing systems. Available forage mass is the single most important constraint to animal productivity in grazing systems (Sollengerger and Vanzant 2011), but quality relationships among feed sources are also important, especially when those sources are seasonally variable both in supply and quality.
Is there any awareness if the technique has been implemented outside of primate nutritional ecology and/or in domestic ruminant grazing systems?
Article Geometry of nutrition in field studies: an illustration usin...
One could get some handle on this by looking at forage samples collected at harvest for grazing-type crops that are harvested for hay, haylage or silage. Crops are harvested from April to October across much of our dairy areas and some labs like Dairy One or Cumberland Valley probably have good databases that could be mined. This is not the same as mixed species pastures that are in intensive grazing, but at least it would be a place to start. Other data could be borrowed from researchers around the country that have collected samples for analyses in grazing studies. A sort of meta-analyses of these data might be useful. Finally, soil mapping data might be useful in making some simulations about changes that might occur with different precipitation pattens. NRCS might be a good source for some of this data.
Thank you for the reply. For similar situations in Indian extensive systems, I've extracted nutritive value for ration components similar to those found in the field from the CNCPS feed library, Dairy One database and from the literature. However, U.S. databases are not necessarily representative of tropical forages and other available ingredients, especially given seasonal changes in forage availability, supply, and quality. I've considered collecting samples of common ingredients in grazing systems, and analyzing for a specific set of nutritive value parameters. I think insights could be gained from analyzing these relationships using the nutritional geometry approach, especially when total and ration component-specific DMI data are not available. Your suggestion to test this approach in a meta-analysis using existing databases could be a good first step.
I only have data from Vietnam. At this stage this is more of an inquisitive question, not something I'm trying to apply right now. I work with another doctoral student at Cornell that may have the opportunity to apply nutritional geometry to her work in extensive Indian systems. It could be particularly appropriate, because measuring DMI for available ingredients in extensive goat systems is very difficult. It could be a future research direction.
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