Rumen-protected fats - high-C16 supplements
A further common group of fat supplements are those categorised as ‘high-C16’ fats, containing close to 100% fat and characterised by palmitic acid (C16:0) concentrations typically 80% or above and near-neutral odour. Several classic and more-recent studies have demonstrated the milk fat-stimulating effect of this fatty acid (concentration and yield) with potential mechanisms including an increased absorption efficiency, preferential usage for milk fat triglyceride synthesis and stimulation of triglyceride synthesis through preferential attachment of C16:0 at specific sites on the triglyceride.
As demonstrated in Tables 1 and 2, responses to C16:0 supplementation (2% of dietary dry matter) are variable and likely reflect differences in stage of lactation, basal diet fat concentration, genetics and duration of feeding amongst others. These data indicate differential use of the C16:0 fatty acid supplements in support of milk and milk fat production and it is important to remember that the greater the proportion of the C16:0 supplement used for milk fat production, then the lower the proportion available for oxidation to supply energy for milk and other productive purposes.
Table 1 Milk production effects of dietary supplementation with C16:0 fatty acids (Piantoni et al., 2013)
|Milk yield (kg/d)||44.9||46.0||0.04|
|Milk fat (%)||3.29||3.40||0.01|
|Milk fat yield (kg/d)||1.45||1.53||0.001|
Table 2 Milk and milk fat production effects of offering C16:0 fatty acids (De Souza et al., 2015)
|Milk yield (kg/d)||35||35||NS|
|Milk fat (%)||3.99||4.25||<0.01|
|Milk fat yield (kg/d)||1.39||1.48||<0.01|
However, many of these supplements have an unsaturated fatty acid concentration of 10% or more. These ‘softer’ (low melting point) fatty acids are potentially released in the rumen where they may exert negative effects as noted previously. Volac Wilmar’s newly-developed Mega-Fat 88 product has overcome this issue by supplying a concentrated source of high-melting point C16:0 (88%) and balancing the remainder with other high melting point fatty acids (primarily C18:0) which may be used more directly as an energy source.