Glycerol from biodiesel production: the new corn for dairy cattle

Abstract

Glycerol, also known as glycerin, is a colorless, odorless, hygroscopic, and sweet-tasting viscous liquid. It is a sugar alcohol with high solubility index in water and has a wide range of applications in the food, pharmaceutical, and cosmetic industries. The use of glycerol in diets for dairy cattle is not novel; however, this interest has been renewed due to the increased availability and favorable pricing of glycerol as a consequence of recent growth in the biofuels industry. Experimental evidence supports the use of glycerol as a transition cow therapy but feeding rates are low, ranging from 5 to 8 % of the diet DM. There is a paucity of research that examines the use of glycerol as a macro-ingredient in rations for lactating dairy cows. Most reports indicate a lack of effect of addition of glycerol to the diet when it replaces corn or corn starch. Recent feeding experiments with lactating dairy cows indicate replacing corn with glycerol to a level of 15% of the ration DM does not adversely effect milk production or composition. Milk production was 37.0, 36.9, 37.3, 36.4 ± 0.6 kg/d and feed intake was 24.0, 24.5, 24.6, 24.1 ± 0.5 kg/d for 0, 5, 10 and 15% glycerol treatments respectively and did not differ (P > 0.05) except for a modest reduction in feed intake during the first 7 days for the 15% glycerol treatment. Glycerol fed to dairy cattle is fermented to volatile fatty acids in the rumen and early reports indicated that glycerol is almost entirely fermented to propionate. In vitro data indicates glycerol fermentation increases the production of propionate and butyrate at the expense of acetate. Rumen microbes appear to adapt to glycerol feeding and consequently, cows fed glycerol also require an adaptation period to glycerol inclusion. Debate exists regarding the fate of glycerol in the rumen and although most reports suggest that glycerol is largely fermented in the rumen, the extent of rumen digestion may depend on level of inclusion in the diet. Data are lacking regarding the rates of rumen fermentation of glycerol at intake levels for high producing dairy cattle. Current data indicates that glycerol can be included in diets fed to dairy cattle at macro ingredient levels; however, additional information is needed to permit a full appreciation of the feeding value of glycerol and the resulting impact on cow health and productivity

Performance, rumen development, and carcass traits of male calves fed starter concentrate with crude glycerin

“…Crude glycerin is a by-product derived from oil and fat transesterification that is generated in approximately 10% of biofuel production (Rahmat et al, 2010) and has aroused great interest as a food alternative for feeding ruminants due to its energetic value that is similar to that of corn (Donkin, 2008).…”

Glycerol inclusion levels in corn and sunflower silages

“…When used as an energy source in ruminant diets glycerol can be converted into glucose in the liver, providing energy for the cellular metabolism (Donkin, 2008) and when it is not recovered by the portal vein presumably can be converted into propionate in rumen, contributing to the gluconeogenesis (Chunget al, 2007). Donkin et al (2009) consider glycerol as feed ingredient for cattle and may be included in the diet without deleterious effects, replacing corn in feed production.…”

Anatomopatologia de amostras de bovinos alimentados com glicerol

“…alternativas energéticas para alimentação animal, como a glicerina bruta/glicerina (DONKIN, 2008). Por meio do processo de transesterificação metílica, na qual os óleos vegetais ou gordura animal são misturados com metanol associado a um catalizador (ácido ou básico), o biodiesel é produzido e a glicerina bruta é extraída com teores de glicerol podendo variar de 46,48 a 89,2% (LAGE et al, 2010;ZACARONI, 2010).…”

“…Entretanto, devido ao fato do mesmo ser fermentado intensamente pelas bactérias do rúmen pode promover o aumento na concentração de ácidos graxos voláteis (DONKIN, 2008), favorecendo assim, a diminuição do pH no rúmen (MACH et al, 2009;WANG et al, 2009) e em dietas mal balanceadas pode ocasionar distúrbios metabólicos e consequentemente provocar injúrias aos ruminantes. PARSONS et al (2009) testando até 16% de inclusão de glicerol contendo 85,7% de glicerol e 0,09% de metanol na alimentação de 373 novilhas que recebiam dietas com 94% de concentrado e verificaram que 11,2% dos animais apresentaram abscessos hepáticos, mas não encontram significância entre o aumento da inclusão do glicerol e a presença dos abscessos.…”