Pasture Sampling versus Dung Sampling
It?۪s called being pro-active. In this century of innovative graziers, methods such as dung sampling and pasture sampling are helping farmers to identify deficiencies in the diet of their production animals. This enables them to amend these deficiencies, maximising the production of their enterprise and increasing profit margins. Yet the question is, how accurate are these methods really? And which one will allow you to manage your herd better?
It is a debate that will continue until something more proven comes along, so for now, it simply comes down to personal preference and method familiarity. Arguably one is better than the other but that depends on who you talk to and how much experience they have had with one method or the other. Only one thing is certain: the aim is to determine the quality of the ruminant diet so that deficiencies may be accounted for and met with a suitable pasture supplement.
Neither sampling option is 100% accurate; Dung sampling is a predictive model based on a database of information, it is cheaper than pasture sampling but highly variable. The same can be said for pasture sampling as it gives an accurate pasture analysis but does not tell you how much is actually available to the animal and utilised, and how much is not. That is unless you do both!
It is however arguable that investing money to analyse both pasture and dung samples may not be financially worthwhile, and pasture quality is forever changing so technically you would have to be taking samples at least every month to be super accurate.
At Top Country, we tend to prefer pasture sampling because at least we know what?۪s going in and we can partially account for other variables such as how much is absorbed etc. We especially like to pasture sample when we are formulating a custom ration to suit your herd where pasture or forage quality is especially important in balancing the ration.
Below are two tables comparing the positives and negatives of the two options _Take a read and decide for yourself which is the best sampling option for you to determine the deficiencies of your herd!
| Sample Type
- Accurately determines the dietary value of the pasture sample provided.
- Measures the actual quantities of each dietary element in that particular pasture sample, therefore you know the actual values that are available to your animals.
- As the seasons change and the pasture develops through its different stages of growth, if you have a pasture sample tested at each growth stage and in the differing seasons, this can be used as a database to refer to each year to help predict the quality of your pastures.
- Only provides analyses of the pasture selected for sampling, therefore it is unlikely that the sample will reflect the complete diet as it may not take into account browse or herbage that the animals may be consuming, nor the percent inclusion of each different fodder in the diet.
- You know what is going ?IN? but you cannot measure exactly how much of that is actually being utilised by the animal.
- The exact quantity of diet is unknown and therefore is a prediction.
- More expensive than dung sampling, mainly due to the wet chemistry needed to determine the mineral levels.
- Does not take into account the changes that have taken place in pasture in time between sampling and results being available. Therefore results will tell you what your pasture ?was?۪ 2, 3 or 4 weeks ago, not necessarily what it ?is?۪ now.
- Cheaper than pasture sampling.
- Results indicate what the animals are excreting, therefore predictions are made as to what the body IS utilising.
- Attributes of animals such as gender, species, pregnancy status, age, or parasite burden will affect their dietary requirements and this is reflected in the results of a dung sample.
- Many of the values are only a prediction of diet not an actual measured quantity. The predicted figures are derived from mathematical relationships and formulas developed from a large number of matched diet and faecal samples.
- The measure of minerals in the dung, such as phosphorus, can be misleading as it cannot be distinguished where the phosphorus has come from. It may not have come from the diet but from bone reserves, therefore the results could lead to a misdiagnosis of deficiencies.
- Dietary N is misrepresented as dung sampling cannot take into account the N from supplementation, such as urea and Granulated ammonia.
Authors: Pip Hodgson & Elsie Dodd