Nathaly Ana Carpinelli
Animal Scientist, UFPel
Animal Production MS, SDSU
Commercial Coordinator, Nutricorp
The use of lipid-based energy supplements can be a strategy to increase energy density in the diet of dairy cows. In addition, they can serve as a source of essential fatty acids (Age), increasing the absorption of fat-soluble vitamins (A, D, E, and K) and diet palatability, as well as promoting a lower ruminal heat increment and improving the homogenization of ingredients during the mixing of the diet/feeds (Palmquist, 1988; Zinn & Jorquera, 2007).
This type of supplement can be added to the diet of various animal categories, provided it is monitored by the farm's nutritionist. Lipids can serve as an alternative for periods of low dry matter intake (CMS), such as the transition period. In this phase, it is known that cows decrease DMI mainly before calving, and therefore, supplementation could be done during the dry period aiming to maximize energy intake even under a low DMI. In addition, due to the positive effects on reproduction, supplementation can be a good option for heifers or lactating cows before the start of the reproductive protocol. Finally, the use of this supplement in lactating cows can bring benefits to the animals' productive aspects, in addition to replacing energy ingredients that are causing a high cost in the diet.
Calcium salts of fatty acidsSCAG) are lipid molecules encapsulated with calcium soaps, in order to decrease ruminal biohydrogenation and the consequent antimicrobial effect of fatty acids (AG) in the rumen. Most FAEC available on the market generally present high concentrations of long-chain FAs, which come mainly from plant sources and may have a saturated or unsaturated chain. In these sources, the most observed FAs include palmitic acid (C16:0), stearic (C18:0), oleic (C18:1) and linoleic (C18:2n-6) (Loften et al., 2014).
The advantages of using SCAG in the diet of dairy cows are:
- Effect bypass through the rumenProtected lipids escape the ruminal fermentation process. For monounsaturated (C18:1) and polyunsaturated (C18:2) FAsn-6) protection is even more important, as they become more susceptible to the process of ruminal biohydrogenation through the action of certain bacteria (Butyrivibrio fibrosolvens e Anaerovibrio lipolytica).
- Greater supply of FA to the duodenumLipids go directly to the duodenum, where they become available for absorption and utilization in metabolism.
Therefore, when SCFA are included in the diet, they serve not only as a source of energy, but can also act on ruminant metabolism and contribute to productive and reproductive functions, demonstrating their nutraceutical function (Williams & Stanko, 2000). Based on this, the objective of this article is to present the positive effects of supplementing different FA on the metabolism and health of dairy cows.
DATA IN DAIRY CATTLE
Rabiee et al. (2012) conducted a meta-analysis and meta-regression to evaluate the effects of supplementing different fat sources on milk production and composition in dairy cows. For the study to be included in the analysis, certain criteria were used:
- Articles published in peer-reviewed journals after 1980.
- Crossover experimental designcrossover or Latin square) was excluded from the analysis.
- Lactating cows only.
- Comparison with a group not supplemented with any lipid source.
- Five lipid sources were included: tallow, calcium salts of palm fat, oilseeds (whole cottonseed and soybean products and, in one case, with free oil), pelicular fat, and other calcium salts.
- Had there not been supplementation with a marine lipid source.
- Present the statistical analysis.
The final dataset analyzed in the review by Rabiee et al. (2012) covered 38 studies, resulting in 86 comparisons. It is worth noting that this review did not place a limit on the inclusion of lipid supplements, which often may not represent the reality of dairy farm nutrition. However, the inclusion of lipid supplements showed an increase in milk production (1.05 kg/cow/day), as well as in milk fat percentage and yield. In contrast, lipid supplementation decreased dry matter intake (CMS), thus resulting in better efficiency for milk production.
In general, most experiments with lipid supplementation in the diet of dairy cows suggest a positive effect on milk production and composition. According to Palmquist (1994), this occurs due to increased total energy intake, more efficient ATP generation vs. volatile fatty acids (AGV) and by the incorporation of long-chain fatty acids into milk fat. Furthermore, a proposed mechanism for the increase in milk production by medium-chain fatty acid supplementation is the “glucose sparing”in the mammary gland, for example. This glucose that is not used for milk fat production ends up being directed toward other processes, such as lactose synthesis and milk production (Palmquist & Jenkins, 1980).
Lipid supplements found on the market present different profiles and percentages of fatty acids (FA) in their composition, resulting in distinct productive and metabolic responses in dairy cows. In a recent study, de Souza et al. (2018) evaluated the effects of altering the proportion of long-chain fatty acids using different lipid supplements vs. a control diet. In summary, the observed effects of each fatty acid were:
- Palmitic acid (C16:0): increase in milk production and milk fat.
- Stearic acid (C18:0): increase in DMI and milk production.
- Oleic acid (C18:1): replacement of body fat, resulting in a more accelerated maintenance and/or recovery of body condition score (ECC).
- Linoleic acid (C18:2n-6): inflammatory process, immunity and embryonic development. In addition, there is an inhibition in milk production, milk fat synthesis and DMI, associated with the biohydrogenation process and the formation of intermediates in the rumen.
- Linolenic acid (C18:3n-3): inflammatory process, immunity, and embryonic survival.
Saturated fatty acids
The use of saturated fatty acid-based supplementsAGS) has been showing positive results in dairy cattle. The most widely used are C16:0 and C18:0, derived mainly from palm and vegetable fats, respectively. In a literature review, Loften et al. (2014) described the action of C16:0 and C18:0 in the metabolism of dairy cows and demonstrated that, although their functions are specific, they still have complementary roles in metabolism.
The absorption percentage of these FAs in the duodenum is the same, however the concentration in the tissues may be different (Loften et al., 2014). Douglas et al. (2007) reported the FA profile in adipose tissue, liver, and blood plasma, and observed that C16:0 is more abundant compared to C18:0. However, during the period of negative energy balance (BEN), C18:0 does not accumulate in the liver, showing that it is possibly used for oxidation or secreted into the milk. In summary, the review demonstrates that the combined supplementation of C16:0 and C18:0 can optimize milk production and cow performance. Therefore, the use of supplements containing both FAs can be beneficial for the animals.
The isolated effect of AGS has also been reported in the literature. Mosley et al. (2007) supplemented different levels (0, 500, 1,000, and 1,500 g/d) of palmitic acid (87%; C16:0) to dairy cows during lactation. Supplementation at 500 g/day led to an increase in dry matter intake, milk yield, fat and protein production, and milk fat percentage. Lock et al. (2013) and Piantoni et al. (2013) supplemented palmitic acid (86%; C16:0) at a rate of 2% of dry matter (MS) and observed an increase in milk and fat production, with little or no effect on the synthesis ‘de novo’ of fatty acids in milk.
In metabolism, de Souza et al. (2019) reported the effect of C16:0 in dairy cows from the immediate postpartum period until peak milk yield. The treatments were divided into immediate postpartum (PPI; 1-24 days), containing a control diet (CON) or C16:0 supplement (PLM; 1.5% from MS). At peak milk production (PPL; 25-67 days), the animals were divided into 4 groups: cows that received CON in the VAI and LPI (CON-CON; cows that received CON in the PPI and switched to PLM in the PPL (CON-PLM; cows that received PLM in the PPI and switched to CON in the PPL (PLM-CON); cows that received PLM in PPI and PPL (PLM-PLM). Blood samples were collected on days 5, 12, 19, 33, 47, and 61 postpartum to determine blood parameters related to energy, mineral, and endocrine metabolism. In this study, the authors observed an increase in non-esterified fatty acids (AGNE) of animals supplemented with C16:0 in the PPI, but this effect is associated with greater loss of BCS and live weight (PV) (de Souza e Lock, 2018) at this stage. Furthermore, PLM supplementation caused a drop in insulin concentration during both periods, a fact that may be associated with better energy direction toward milk instead of body reserves, thus promoting effects on insulin secretion or tissue sensitivity to insulin.
Stearic acid supplementation was reported by Piantoni et al. (2015) and Boerman et al. (2016). The addition of stearic acid (98%; C18:0) at the 2% level of the MS increased CMS, milk production, and milk components, without affecting feed efficiency, ECC, and PV (Piantoni et al., 2015). In another study, supplementation with stearic acid (93%; C18:0) at different levels relative to the dry matter (DM) of the diet (0, 0.80, 1.50, or 2.30% DM) resulted in a linear increase in CMS, with no effects on milk production and/or composition. Furthermore, increasing supplementation levels resulted in a modest increase in C18:0 and C18:1 fatty acids cis-9 in milk fat, which is not sufficient to affect the milk fat content (Boerman et al., 2016).
Yanting et al. (2019) reported the difference in effect between C18:0 and C18:1 cis-9 in a diet containing low or high FA levels at the beginning of lactation. Metabolic parameters were analyzed and blood was collected postpartum at weeks 4, 6, 8, 10, and 12. These authors observed that supplementation with a low level of C18:0 promoted an increase in circulating concentrations of beta-hydroxybutyrate (BHB), suggesting that C18:0 supplementation has an effect on lipid metabolism and can synthesize more BHB through alternative metabolic pathways.
The combination of the two AGS was evaluated by Western et al. (2020). They assessed the effects of (1) a control diet, (2) a diet supplemented with C16:0, and (3) a diet supplemented with C16:0 and C18:0. The supplement was added at a rate of 1.5% of DM. Milk production increased in animals supplemented with fat, while the C16:0-based supplement had positive effects on corrected milk production (ECM) and fat content in the milk. On the other hand, no positive effects of FA supplementation and/or the FA profile on DMI and BW of the animals were observed. According to these results, the authors concluded that animals producing around 45 kg of milk respond better to C16:0 supplementation than to a combination of C16:0 and C18:0. In blood parameters, fat supplementation had no effect on insulin and BHB, but increased NEFA concentration vs. the control diet.
Unsaturated fatty acids
Supplementation of monounsaturated (C18:1) and polyunsaturated (C18:2) FAsn-6) for dairy cattle must be done with great caution and monitored by the farm's nutritionist, as it can promote a decrease in milk fat. According to Bauman & Griinari (2001), milk fat depression is a classic concept and commonly observed in scenarios where plant and/or marine lipid supplements are offered to the herd. The explanation for this is that these FAs undergo the ruminal biohydrogenation process. Under specific conditions, intermediate compounds, termed conjugated linoleic acids (CLA; trans-10, cis-12 CLA), which modify the functioning and synthesis of fat in the mammary gland by altering the expression of genes related to lipid metabolism (Bauman et al., 2011).
Studies have observed that SCAG supplementation of trans-10, cis-12 CLA resulted in a consistent reduction in milk fat content in dairy cows at different stages of lactation (Bauman et al., 2011). Furthermore, a recent study indicated that supplementation with CLA-SCAG (15 g/kg DM) reduced milk fat content, accompanied by a decrease in the diameter of milk fat globules (Xing et al., 2020). This is because, in the mammary gland, milk fat is secreted in the form of globules—unique structures composed mainly of triglycerides enclosed within a lipid membrane. Some studies have evaluated the effect of polyunsaturated fatty acids on the productive performance of dairy cows. Macedo et al. (2016) demonstrated that supplementation with SCAG (250 g/day) combined with a low concentrate level (3 kg/day) resulted in an increase in milk production and had no effect on milk solids and fat content. In contrast, de Souza et al. (2017) evaluated the effect of including soybean oil-based SCAG (4.91 TP3T DM) on the production parameters of pastured dairy cattle. The animals received the treatment during weeks 3 and 16 postpartum, and the effect carryover was evaluated throughout lactation. The soybean SCAG-based supplement resulted in a drop in fat content and DMI, but promoted low mobilization of body reserves and little variation in BW and BCS of the animals throughout lactation.
According to the review by Palmquist & Jenkins (2017), some studies have shown effects of the use of polyunsaturated fat on animal metabolism. Abomasal infusion of C18:2 n-6 C18:3 n-3 affected oxylipin biosynthesis in mammary tissue and mastitis severity in dairy cows (Ryman et al., 2017). Oxylipins are mediator lipid molecules that help regulate the inflammatory response. The main precursors of oxylipins are polyunsaturated fatty acids (PUFA), and their synthesis depends on the availability of these fatty acids and the enzymes involved in the metabolic pathways. Current literature supports the concept that supplementation with diets containing polyunsaturated fatty acids can affect biosynthesis and alter the functional capacity of these cells involved in the inflammatory response (Sordillo, 2018).
Studies in vitro They reported the effects of FAs on bovine mammary epithelial cells and concluded that supplementation with CLA and AGE affected the cellular response against oxidative stress (Basiricò et al., 2017). Another study in vitro demonstrated that FA supplementation reduced the expression of pro-inflammatory and anti-inflammatory cytokines (Dipasquale et al., 2018). In dairy cows, the change in the C18:2 ratio n-6 C18:3 n-3 affected immune function and the inflammatory response during lipopolysaccharide challenge (Greco et al., 2015).
CONCLUSION
Energy supplements have a different fatty acid profile that can act in various ways on animal metabolism, increasing animal productive efficiency, with responses in milk production and composition and DMI, for example. A detailed evaluation of the supplement, the diet, and the animal category is of paramount importance to consider the addition of a lipid source to the animals' diet. Furthermore, we as technicians must consider the producer's goal and the expected results of adding a lipid supplement.
At the present time, with the high price of inputs (corn, soybean, cottonseed), supplementation with SCAG becomes a viable alternative to minimize costs within the production system, in addition to promoting many positive results for the herd.
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