FEATURE: Variability in the basal diet's (ensilage, urea-FCR) volatiles and the inherency in its statistical design, parameterization and analysis.
It has recently been brought to our attention at Skye Blue that the use earlier by our Owner/Principal D. A. Flores (pen name) of the toluene-corrected DM/OM determination (see: AOAC) can possibly be further "aired out" as to its usefulness as an option in practice in certain feed treatments in feeding trials: is it true that correlates are more sensitive between roughage diets and with the addition of urea-N with pre-treated feed crop residuals (FCR) (yeast-based) or vs. corn.
The principle is to use toluene correct for volatile fatty acids (VFA), ammonia (NH3) [and other NPNs (non-protein nitrogenous cpds.)] being significant as energy substrates, and the essential nitrogen (N) pool amongst fibrolytics, respectively. (It is believed that the amines which represent potential toxicity and in some cases affecting intake on silages are not sensitively assayed using this correction as a tool.)
The statistical basis of applying the technique to treat numbered data from pooled studies either with FCR or corn in feeding trials is to remove variability and the overestimation of parameterization leading to improve precision and accuracy in predicting feeding correlates such as growth performance and dairy lactation.
When interpreting results it is asked where the source of error is in the nos. It is known that the error is inherent in the biological data and has to be controlled by experimental design: e. g. randomized cross-over is a good choice where a minimum no. of animal subjects are selected for maximum no. of data point obtained along with the treatments and no. of animals per treatment per time. A good estimate is 60 observations for a Scattergram to plot the data per experimental treatment with its significant correlate statistic and its linearized curve. Meaning for 1 experimental treatment: 3 animals per set X 2 with crossover periods making for 6 observations and 5 discrete treatments in gradations of 20 points in varying the % treatment (A- FCR- yeast-based, B- corn) with the basal part of the ration of silage, viz. 0, 25 50, 75, 100% in treatment proportions.
Our end remarks are to say that where there are significant "interferent" volatiles that are correctable in feed substrates "as is" or "as fed" that statistical analysis and its concerns for accuracy (stand error of the mean, SEM), and precision related to sensitivity in picking up differences in statistical treatment data, can be managed better along with this add on of a technique. Granted, as noted, the analyses adds a separate protocol along with fresh-frozen samples to be freeze-dried to quantitate, in toluene, the volatile VFAs and NH3 (salts of both) but could be semi-automated like our earlier suggestion to use our design apparatus of a dedicated ammonia (NH4+) electrode for both ammonia directly and total nitrogen (TN) (cf. to Kjeldahl TN determination).
(We can oblige the release of more information on our proprietary TN dedicated electrode or probe for feeds and other biological sample analyses.)
(c) D. A. Flores. 2024-2050. Skye Blue (SB) Internet. Port Coquitlam, B. C. V3B 1G3 Canada.