Rumen-protected fats

Preparation of free-flowing rumen-protected fats. 

Casutt, M. M., Scheeder, M. R., Ossowski, D. A., Sutter, F., Sliwinski, B. J., Danilo, A. A., et al. (2000). Comparative evaluation of rumen-protected fat, coconut oil and various oilseeds supplemented to fattening bulls. 2. Effects on composition and oxidative stability of adipose tissues. Arch Tieremahr, 53, 25 44. 

Modern developments in the manufacture of rumen-protected and rumen-inert fats, together with increased understanding of ruminal and... 

Oleic acid was increased to 48% of total milk fatty acids by feeding oleamide as a rumen-protected source of oleic acid (Jenkins, 1998). The response was nearly linear up to 5% of supplement in the diet dry matter. Proportions of all de uovo-synthesized milk fatty acids, except butyric, were reduced (Jenkins, 1999). LaCount et al. (1994) abomasally infused fatty acids from canola or high oleic acid sunflower oil into lactating cows. The transfer of oleic acid to milk fat was linear (slope = 0.541 0 350 g infused/ day) the proportion of oleic acid in milk fat increased and proportions of all de novo-synthesized fatty acids, except C4 and C6 decreased. The proportion of Ci8 o also was unchanged. Linoleic acid from canola also was transferred linearly (slope = 0.527 0-90 g infused/day). These transfers from the intestine are nearly identical to that reported by Banks et al. (1976). Hagemeister et al. (1991) reported 42 to 57% transfer of abomasally-infused linolenic acid to milk fat. 

Precht, D., H. Hagemeister, W. Kanitz, and J. Voigt, irons Fatty Acids and Conjugated Linoleic Acids in MUk Fat from Dairy Cows Fed a Rumen-Protected Linoleic Acid Rich Diet. Kieler Milchwirtschafiliche Forschungsberichte 54. 225—242 (2002). 

Fig. 10.3. Effect of long-term dietary supplement of CLA on milk fat in lactating cows. Cows received a rumen-protected CLA supplement (O) or an equivalent of saturated fat (control ) for 20 wk during established lactation. Adapted from Perfield et al. (100). 

In a meantime, primiparous cows were fed the same basal diet than in the experiment described previously and supplemented daily with folic acid and rumen-protected methionine. The effects of weekly intramuscular injections of saline (0.95 NaCl) or 10 mg of vitamin Bj2 on milk production were monitored from 4 to 18 weeks of lactation. Supplementary vitamin Bj2 tended to increase milk yield from 28.5 to 31.1 kg/d and increased energy-corrected milk as well as milk yields of solids, fat and lactose but had no effect on dry matter intake or milk composition. Furthermore, packed cell volume and blood haemoglobin increased and serum methylmalonic acid decreased in cows that received vitamin Bj2 injections. The first observation suggests that low vitamin B 2 supply interfered with folate metabolism because folic acid deficiency, through its role in DNA synthesis, affects hematopoiesis (Bills et al., 1992). The second one indicates that low vitamin Bj2 supply interfered with the other vitamin B j 2-dependent enzyme, methylmalonyl-CoA mutase. These findings supported the hypothesis that vitamin Bj2 supply is suboptimal in early lactation (Girard and Matte, 2005) and may have limited the potential role of folic acid in these first studies. 

Aim of the study was to evaluate the effects, on milk fatty acid composition, of sources of rumen inert fats fed to transition dairy goats hydrogenated pahn oil (HPO), rich in saturated FA or protected fish oil (PFO), rich in long-chain n-3 PUFA. 

For mminant fat to become directly responsive to dietary unsaturated fats, it is necessary to protect the lipids against saturation by rumen microorganisms. The alteration of the lipid content of mutton by the feeding of such protected oil supplements has been described (14). Also, it has been shown that a diet of extruded soybeans increased the linoleic acid and linolenic acid contents of steer adipose tissue (15). 

Ruminants are equal to or superior to nonruminants in their ability to digest saturated fatty acids, but unsaturated fatty acids fed conventionally have lower digestibility due to rumen biohydrogenation. Unsaturated fatty acids, fed in protected form, are digested equally in ruminants or nonruminants. Moderate levels of added fat (up to 3% of feed dry matter) are 85% truly digestible (52). 

Fats not protected for escape or bypass will be altered if fed to ruminants. Within limits, triacylglycerols are hydrolyzed, and the polyunsaturated fatty acids are biohydrogenated by rumen bacteria enzymes. 

The composition of beef tallow is modified by diet. Dietary fat can be encapsulated in protein hardened with formaldehyde in order to protect the fat from the microflora in the rumen (see milk). Unsaturated fats fed in this way produce more unsaturated depot fats and milk fat (Garrett et aL, 1976). 

---