Please find the following web site:

http://www.nature.com/nprot/journal/v1/n4/abs/nprot.2006.225.html

I think it will help for you.

It would be easier using the alkanes technique if the slow release device was available. Otherwise you need to dose twice daily alkanes (or other compounds, such as TiO2) in gelatine capsules. Cattle in temperate environments are usually offered high quality herbages, which have a rapid rate of passage so dosing a marker for faecal output has to be twice a day. We can probably bring back the slow release capsules if there was enough researchers wanting to use it. 

In Portugal there are two colleges that has worked extensively with n- alKanes: Miguel Bugalho ([email protected])  and Luis Ferreira ([email protected])  from Instituto Superior de Agronomia and Universidade de Trás-os-Montes e Alto Douro, respectively, 

I think they can help you

Marina Castro

I have found the n-alkanes to be a highly reliable technique to estimate dry matter intake, but with the added advantage of allowing to estimate diet selectivity.That is a fundamental feature for me, as I work with multi-species grazing systems that combine at least three different species.

There are several features of the n-alkanes technique that need to be considered for successful adoption into a lab:

1. Method of external marker dosage to the animals: Controlled release devices are no longer available in the market. As Cesar says,that means dosing in gelatine capsules. We are currently trying to use beewax, but have no results of that research yet.

2. Laboratory procedures: It can be said, that these are more elaborated that those required for other intake markers. I would suggest reading the following article: Dove, H. and Mayes, R.W. 2006. Protocol for the analysis of n-alkanes and other plant-wax compounds and for their use as markers for quantifying the nutrient supply of large mammalian herbivores. Nat Prot, 1: 1680-1697. This is the best description of the laboratory work associated with the n-alkane technique that I have found so far.

3. The choice of marker: It can be alkanes, but also long chain alcohols (see Dove and Mayes, 2006).

All the best,

After using n-alkanes as external does or external markers for total fecal output. Please find attached the protocol of n-alkanes analysis in laboratory and the original paper of the technique.

Best regards

Ahmed R. Askar

Dear Martino!

There is a lot of info in the web about this technique and its advantages. I´ve been working with it for a while. 

If i´m not wrong, Masato Yayota sent you a link to dove and mayes work and the protocol of analysis. 

Here I´m sending some other works that may help you. You will have to take some tips in consideration. For example, what Cesar Pinares says it´s true, a release controle capsule will help you in the dosing procedure, although they have been out of market for some years, so it will be hard to find some.

If you need to determine intake, dosing with C32 will just be ok, but if you need further info (fecal output, digestibility), you will have to know about the n-alkane fecal recovery for some, so perhaps you´ll have to perform a small fecal recovery experiment for the animals and diet you´ll be working with.

If you need any particular info, let me know!

Hi,

I've been working with alkanes in grazing milking sheep and in this last experiment I used beeswax applied on ground barley. I still don't have data available but I offered the marked barley at the milking parlor, twice a day. By doing this, I tried to avoid unnecessary added stress on the ewes. I also performed a fecal recovery experiment for this type of animals. I intend to analyse for long chain alcohols as well to complement the information given by alkanes.

I had help from Luis Ferreira ([email protected]) from Universidade de Trás-os-Montes e Alto Douro.

The alkane method is generally a robust one, allowing to estimate intake, digestibility and diet composition simultaneously and with precision. I have evaluated the method for tropical grasslands and it works quite well.  The faecal recovery rate of the alkanes may vary according to diet and species of animals, and it is important to make sure that the dosed and natural alkanes used in the double alkane method to estimate intake have similar recovery rates. So diet specific recovery trial may be necessary. The accuracy of the intake estimation depends on whether this assumption holds true. Controlled release alkane capsules may not be available on the market at the moment. Two times daily dosing  appears fine for grazing animals. I used molasses based alkane boluses and it worked well.

Here I´m sending my e-mail in case you need to contact me!!

[email protected]

Greets and have a nice weekend!

Cr2O3 green also can be used to estimate intake although it has some inherent limitation still work well.   

You can see the literatures mentioned by A.R. Askar and Dr. Chopa.

Dear Martino,

Every technique has its odds, and the n-alkane method is not an exception. First of all, when the animals graze multispecies swards there is a need to accurately estimate botanical composition of the diet ingested. This is so because including the n-alkane profile of a species not really consumed by the animals in the calculations will biass the results. Hence the first step would be assessing what plants are and what are not actually consumed by the animals (and what plant parts, as well). Obviously, animal preferences will dramatically change depending on stocking rate and biomass availabity.

Then the technique requires a knowledge of the individual faecal recovery of each alkane. This can only be carried out indoors. As faecal recovery is greatly affected by animal variation, that should be assessed in the same animals that will be later placed in the pasture. The administration of an even chain alkane to the animals, and the assumption that odd chain alkanes with a similar number of C atoms have the same recovery, is wrong as 'natural' alkanes are mainly bond to the particualte phase of the diet and dosed alkanes are mostly vehiculated in the liquid phase. Different rates of passage lead to different recoveries. The 'relative recovery' approach is also useless in grazing conditions.

Finally, the mathematical model used to calculate diet composition is of importance too. There are evidences that using either the Solver routine of the Excel, as suggested by Bob Mayes, or the EatWhat programme, as suggested by Hugh Dove, may give different results. The reasons for that are not fully understood but it seems that both models may not be mathematically equivalent in determined conditions.

You may check the papers published by our group supporting the commnets above.

Best regards, and good luck with your research.

Thank you very much Antonio for your contribute

Best regards

Martino