The utilization of dietary fats by ruminants:I. The digestibility of some commercially available fats

Abstract

SUMMARYThe digestibility of some fats (beef tallow, HEF, herring oil, soyabean oil and maize oil) were studied in balance trials with sheep which had been maintained on the diets for a 35 day period of acclimatization to establish ‘steady state’ conditions. Corrected digestibility coefficients for the individual fats were calculated from a knowledge of the intake and output of lipid on a low-fat basal ration. The difference between the intake of fat and the corrected lipid output (total lipid output minus lipid output on basal ration) expressed as a percentage gave the corrected digestibility coefficients.It was found that the corrected digestibility coefficients for beef tallow was 85%; HEF, 74%; herring oil, 84%; soyabean oil, 83%; and maize oil, 70%. The values for beef tallow and HEF were comparable to similar estimates in pigs. The digestibility of the highly unsaturated soyabean and maize oil were markedly lower in comparison with non-ruminant species. Extensive hydrogenation of dietary unsaturated fatty acids was confirmed. For soyabean and maize oil the corrected output of stearic acid exceeded the dietary intake.

Influence of Level and Source of Dietary Fat on Its Comparative Feeding Value in Finishing Diets for Feedlot Steers: Metabolism

“…In ileal chyme, the relative proportion of stearic acid increased (P < .01) linearly with level of fat supplementation, suggesting that the digestibility of this fatty acid was reduced as a result of level of supplementation. This observation is consistent with other studies (Lennox and Garton, 1968;Andrews and Lewis, 1970) that have demonstrated comparatively lower rates of digestion for stearic acid.…”

“…In light of the extensive biohydrogenation of fatty acids in the rumen and the consistent observation that palmitic acid had a higher intestinal digestibility than stearic acid (Andrews and Lewis, 1970;Johnson and Leibholz, 1980), it appears that one practical index of the feeding value of blended fats is a high palmitic acid concentration.…”

Fatty Acid Digestibility in Lactating Cows Fed Increasing Amounts of Protected Vegetable Oil, Fish Oil or Saturated Fat

“…To compensate for the high ratio of saturated FA in the fat flowing to the intestines, ruminants generally digest saturated FA better than non-ruminants (Andrews & Lewis, 1970a;Andrews & Lewis, 1970b). However, also for ruminants intestinal digestibility of unsaturated FA is higher than for saturated FA (Hagemeister & Kaufmann, 1979), which is most obvious when the ratio of saturated to unsaturated FA is high (Mdler & Barsting, 1987).…”

Effects of supplementation with hydrogenated fish fat on digestion in dairy cows

“…Moreover, the digestibility of such lipids in the small intestine appears high (Andrews and Lewis, 1970 Concentration and composition of VFA in rumen fluid were determined by GLC (Jouany, 1982).…”