NUTRITION ▶▶▶
Protected fats in ruminant nutrition
BY DR SALAH HAMED ESMAIL I
nitially, dietary fats were protected by coating them with protein that was then treated with formaldehyde so that it was not degraded in the rumen. This product did not become commercially viable because of its interference
with rumen fermentation, high cost of manufacture, difficulty in producing a consistently reliable product and the lack of government approval for use of formaldehyde. Progress was, therefore, made in developing protected fats that are not only inert in the rumen but also efficiently absorbed from the small intestine.
The following are the technologies that are currently adopted for these purposes:
Crystalline or prilled fatty acids These are made by liquifying and spraying the saturated fatty acids under pressure into a cooled atmosphere, so that the melting point of the fatty acids is increased and they do not melt at rumen temperature, thus resisting rumen hydrolysis.
Fatty acyl amide This product consists of an FA chemically linked through an amide bound to an amine. This protection technology was used to create rumen bypass methionine, as the amide bond between the carboxyl group of stearic acid or other acyl groups and the amine of methionine resists rumen bacterial breakdown.
Fat composite gels Fat droplets are embedded here within the gelled protein matrix in which the lipids are protected against degradation, modification or removal from the gel during passage through the rumen.
Calcium salts of long-chain fatty acids These products are prepared by the reaction of the carboxyl group of long-chain fatty acids (LCFA) and calcium salts (Ca++). They have the highest intestinal digestibility and serve as an additional source of calcium.
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The addition of fat to the diets of dairy animals can improve the energy balance in lactating cows and hence improves fertility, milk production and other biological functions. The advantages of increasing the energy density of diets without reducing digestibility can be achieved if the dietary fat is protected from hydrogenation in the rumen.
Protected fat and dry matter intake The inclusion of fat in the diet negatively affects cows’ dry matter intake (DMI) due to the following factors which can be avoided, at least partially, by feeding protected fats: • An increase in ruminating time due to negative effects on rumen digestion;
• A slowdown of rumen emptying due to a metabolic effect of LCFA;
• Secretion of unidentified chemical mediators as a response to the flow of digesta into the duodenum; and
• A satiety effect of decreasing digestive motility as a result of intestinal peptide secretion.
PHOTO: MARK PASVEER
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