1. DOES IT MAKE SENSE TO FOCUS SO MUCH IN MILK FAT % AT ALMOST ANY COST?
The use of fats or oils in dairy cattle rations is a common strategy to increase the energy density of the ration (Rabiee et al., 2012) in order to combat the NEB (Negative Energy Balance).and keep milk yield/production level.
In recent years, the search for higher income (which does not always means profitability) has led to an increase in the use of certain fat supplements that help to increase milk fat %. However, the calculation of the economic return and the global effects in the animal (production in the lactation cycle, body condition, reproduction, and metabolic health) are usually out of the purchasing decision process.
In this sense, the fatty acid profile of the fat supplements greatly influences the abovementioned aspects, and as a consequence, dairy farm’s profitability.
Unsaturated fatty acids have a high duodenal digestibility. Particularly, oleic acid (C18:1) improves the solubility and favors the formation of micelle, thus improving the digestibility of total fat in diet.
Examples like this justify the formulation of diets with an approach on fatty acids instead that just fats. However, most feeding systems pay little (if any) attention to fatty acids nutrition, despite the recurrence of "precision animal nutrition". This represents a challenge for nutritionists and feed software.
1.2. Metabolic Effects of Fatty Acids
Cows at the beginning of lactation are genetically predisposed to produce high amounts of milk, which is achieved at the expense of the loss of body fat. In this sense, palmitic acid (C16:0) is substrate for ceramide novo synthesis (McFadden, 2017). In turn, ceramides reduce insulin sensitivity (Rico et al., 2015), increasing non-esterified fatty acids (NEFA) mobilization of from adipose tissue (Rico et al., 2016, Davis et al., 2017), which in practice could mean that adding more palmitic acid to the diet could exacerbates this energy/nutrients partitioning profile, mobilizing excess body reserves, with the consequent risk of the appearance of metabolic diseases, such as ketosis, along with the consequences it carries on both immunity and reproduction.
In addition, from the point of view of dairy products’ quality, different problems have been observed in cheese and butter (e.g. in Holland and UK) as consequence of the increase in dairy products’ melting point (coming from a higher content of C16:0 and of the ratio saturated/unsaturated fatty acids. This also has negative consequences on the healthiness of these products for humans.
In contrast, oleic acid (C18: 0), because of its stimulating effects on insulin, make it to be a desirable fatty acid at the beginning of lactation in order to increase energy partitioning not only to milk production but also body reserves, so that the incidence of metabolic issues and reductions of fertility (as secondary effect) are decreased.
The improvements in total fat digestibility in diet observed when C18:1 is included, provide additional energy and improvements in fertility (quality of the follicle and early embryonic development), which implies a significant improvement in the fertility) (Aardema et al., 2011).
2. THE SOLUTION: THE COMBINATION C18: 1 / C16: 0 (Calcium salts of palm fatty acids)
It has been recently proven (Souza et al., 2017) that balanced fatty acid profiles (C18:1 / C16:0) are recommendable from a global point of view: digestibility, milk production, body fat/body condition, metabolic health, reproductive results. Results regarding digestibility are shown below:
3. PRICE VS. ROI
Therefore, price of the point of C16:0 and the gross income (coming from a higher milk price due to higher content in milk fat %) must not be the sole parameters on which fats’ purchasing decision is based on. Moreover, is the cost differential between different fats being profitable throughout the whole lactation? It is worthy to carry out a simple modeling/estimation of it, which can be carried out just with 4 indicators:
- Production curve
- Milk yield (305 days liters)
- Milk fat %
- Milk fat yield at 305 days (liters)
SUMMARY & CONCLUSIONS
In face of deciding which fat to include in dairy cows’ diets, different aspects must be taken into account. Not only the price of the fat and the potential higher gross income due to higher milk price must be considered. Also the profitability of the investment (along the whole lactation cycle and under each market context) along with the overall effects of the fat supplement must be considered: this means effects on dry matter intake, rumen metabolism, digestibility, milk components synthesis, energy/nutrients parturition, body condition, immune and reproductive systems, and even on dairy products’ quality.
In this sense, a balanced ratio between palmitic and oleic fatty acids (such as that of palm fatty acids calcium salts) has been recommended.
This article was originally published in Far Eastern Agriculture 5, 19.