Uso del glicerol

Here's a study that looked at feeding glycerol byproduct to cattle for various reasons. Please note that the glycerol was from rapeseed-sourced biodiesel, not waste vegetable oil sourced, so the contaminant levels were probably different than WVO sources (though dont' they feed WVO to cattle basically already?). ALso it's unclear what kind of processing the byproduct got- they talk aboutphosphorus content which makes me think that some of it is acidulated with phosphoric acid.

I'm looking for folks knowledgeable about dairy farming to pick apart and translate into plain English what they're saying here. SO I've posted the whole paper- please post any thoughts on it point-by-point:

To quote specific sentences, you type in {quote} insertwhatyouwanttoquote here{/quote}, except thatinstead of curly brackets{} you use regular brackets [ ]

Here's the URL of the original study webpage:
http://www.regional.org.au/au/gcirc/1/241.htm

Glycerol as a by-product of biodiesel production in Diets for ruminants

Angela Schröder and Karl-Heinz Südekum

Institute of Animal Nutrition, Physiology and Metabolism, University of Kiel, 24098 Kiel, Germany, e-mail:schroeder@aninut.uni-kiel.de

Abstract

Glycerol can be derived from the production of biodiesel. It is a glucogenic substance similar to propylene glycol, which has been used effectively to prevent ketosis in high yielding dairy cows. This study was conducted to evaluate the potential of glycerol of three different purities in diets for ruminats. Energy concentrations of glycerols and of glycerol containing dietswere determined in vitro and in vivo as related to different types of concentrates, i. e., high in starch versus low in starch. Glycerols at concentrations of up to 10% of total diet dry matter were compared with starch as rapidly fermentable carbohydrate source as related to estimates of ruminal fermentation, microbial biomass production, and nutrient digestibilities in steers at 85% of adlibitum intake. Additionally, we evaluated the physical, chemical and hygienic qualities of concentrate pellets containing glycerol of different purities at different concentrations and stored under different environmental conditions.

Pellet quality, in particular hygienic quality, was positively influenced by glycerol. Estimated energy concentrations from digestibility trials in vivo were 8.3 and9.5 MJ net energy for lactation/kg of glycerol when glycerol was fed in combination with a high and a low starch concentrate, respectively. From the in vivo data it can be concluded that glycerol of different purities can replace rapidly fermentable starches in diets for ruminants up to concentrations of 10% of diet dry matter without negatively affecting feed and water intake, ruminal nutrientdegradation and whole-tract nutrient digestibilities. Rumen microbial biomass production was not different among the diets containing starch or glycerol. The glucose precursor glycerol may improve energy supply to high yielding dairy cows, both before and after calving and thereby have an impact on health and performance during the entire lactation.

KEYWORDS: chemical composition, energy value,ruminal fermentation, starch, pellet quality
Introduction

In the European Union the turn towards renewable energy sources has increased the production of biodiesel from rapeseed oil (rapeseed oil methyl ester), leaving glycerol as a valuable by-product. Glycerol is a natural, liquid substance of sweet taste which is registered in the European Union as feed additive E 422 (Anonymous, 1995).Lebzien and Aulrich (1993) have reported a high energy concentration (9.5 MJ of net energy for lactation/kg) and glycerol may therefore have benefits to prevent keto-acidosis in the the high yielding dairy cow by increasing the supply of glucose precursors (Johnson, 1955; Fisher et al., 1971; 1973; Sauer et al., 1973). Because data from the United States suggest that 30 to 50% of all dairy cows are...