NUTRITION AND METABOLISM OF FATS IN DAIRY COWS

Organized by the Center for Animal Nutrition, an international symposium on milk cow focused on lipid metabolism was held at Wageningem in collaboration with the same Agrarian University and the Lelystad Research Center.

There are 80 teachers, researchers and technicians mostly European, but also American and a Korean. The morning session (I) was focused on preventing the transformation of fatty acids contained in dietary fodder both during harvesting and forage fodder as well as during bacterial attack and biohydration that occurs naturally in the rumen.

This is to increase the content of polyunsaturated fatty acids in milk, making it more like the acididogue of fodder that the cow has ingested. After recalling that the cow is a natural hydrogenator and therefore naturally diminishes the biological value of the ingested fatty acids because it does not diminish their digestibility, it has relate to how, through different processes and processes, it is possible to protect unsaturated fatty acids, animal ingests or ingests with a natural green diet, ie grazing.

Ultimately, as in humans the diet is too rich in omega 6 compared with omega 3, it is intended to produce a more dietary milk with which it can also get a greater commercial value of it. The afternoon session (II) was much more scientific and focused on liver biopsy techniques.

This technique is capable, if supported by the subsequent PCR and by a detailed meta-analysis, to validate a research scheme to indicate whether or not the activating genes of RNAm and therefore enzymes with specific metabolic or physiological functions are triggered. Specifically, the activation and regulation of PPaR binders has been studied that can activate the peroxisomes in dairy cows, that is, their cellular metabolic bi-turbo.

Session I

The first speaker, j. Wageningem University’s Cone, remembers that cattle ingests large amounts of unsaturated fatty acids in natural grazing rations with green fodder. These fatty acids are mainly composed of oleic acid (C18: 1 cis-9), vaccineous acid (C18: 1 trans-11), conjugated linoleic acid (CLA, C18: 2 cis-9, trans-11) and linolenic acid (C18: 3). The fodder during the silage loses several unsaturated by the effect of bacterial lipase naturally occurring within the mass giving oxidation of the unsaturated.

The maturation stage also influences the PUFA content: the maximum content is estimated in wheat silage 56 days after flowering, then decay. The duration of the silage process is also directly proportional to the loss of PUFA: the longer the time it takes to close the trench and the greater the loss of PUFAs. The opening of the silos increases oxygenation of the same, triggers bacterial activity, in particular lipoxygenation with PUFA reduction.

The researcher then recalls that C 18: 3 in milk is present in the alpha and gamma form and only the first is an omega-3, while the latter is an omega-6. Remember that if the larger the dry matter is collected, the smaller is the composition in omega-3 (alpha form), but the milk is higher. This confirms that omega -3 in the ration if not protected, like all unsaturated fatty acids, interact with cellulosolytics diminishing the number and creating a natural sub-acidosis that can reduce both production and fat in milk.

The second rapporteur, Sterk, of the University of Wageningem, explains the need for human nutrition to reduce the consumption of saturated fat for the benefit of unsaturated ones.

In dairy cattle, significant differences exist between ingested fatty acids (mostly unsaturated) and those that leave rum (mostly saturated by the same).

The aim of the research is to increase the amount of unsaturated fatty acids present in milk, this can be by altering the ruminal profile by increasing the by-pass of the diet unsaturated by avoiding or partially reducing the bio-hydrogenation of the rumen.

In a first study it can be seen that different fat sources in different forms can alter the profile of fatty acids in milk. The protected form, mostly on lipid film, is able to overcome the rumen and vary the composition of the milk.

A second study evaluated different technologies and chemical treatments on linseed oil to test its by-pass fatty acids. Only treatment with formaldehyde was able to decrease the fatty acid biohydrogenation of flaxseed fatty acids.

In conclusion, the profile of fatty acids in milk can be altered by the composition of the fat given in quantity and quality and the diet / concentration ratio of the diet.

In fact, if the ration is too high in fermentable sugars it will have a partial acidification of the rumen and a consequent increase in the ruminal biohydrogenation.

The third report was held by Van Rast professor at the University of Ghent. It offered an original method to reduce the lipolysis and oxidation of unsaturated fatty acids during the silage.

In fact, silage fodder has fewer PUFAs than the corresponding fresh fodder. This is due to a loss of linolenic acid (for oxidation) and lipolysis during the nesting. This leads to a decrease in triglycerides with a consequent increase in free fatty acids in silage and their faster ruminous biohydrogenation (is it also why fat can lower in milk when the trench changes?). This explains the low amount of PUFA in milk and beef.

From his studies, it can be seen that clover clover with respect to loin and ladyl clover protects its unsaturated fatty acids from lipolysis during silencing and ruminous biohydration. This is due to the effect of the red polyphenols contained in the incarnated clover.

This can be explained through three hypotheses. The former consists in blocking the enzyme responsible for lipolysis and biohydrogenation by forming a complex protein-phenol; the second through a natural microencapsulation of fats contained in clover-like clover as in chloroplasts; the third involves blocking lipases for formation of a complex between chinone and lipids.

The fourth Jacobs researcher’s report at Wageningem’s animal nutrition group suggested another method of controlling and reducing the bio-hydrogenation of the gums.

The amount of unsaturated fatty acids in the milk is due to the amount of diet insaturus, the degree of biohydrogenation of the rumen, and the activity of the stearoylCoa desaturase (SCD) enzyme present in the breast gland. This is an endoplasmic enzyme that is able to introduce a cis double bond between carbon 9 and 10 in many fatty acids. The preferred substrate is C18: 0 and to a lesser extent the C16: 0 being converted to C18: 1 cis-9 and C16: 1 cis-9. Furthermore, SCD may also produce cis-9, trans-11 conjugated linoleic acid (CLA) from the desorption of C18: 1 trans-11. CLA isomer has been associated with numerous benefits for consumers such as atherosclerosis, hypertension, and various types of cancer.

The purpose of this research was to find the relationship between fatty acids present in the diet and gene regulation of the SCD in order to increase its production at breast level. Different fatty acid mixtures were made to the experimental bovine animals. Milk production and the quality of the same were not affected by the treatments. The gene expression of SCD was lower with the diet with soybean oil than that with rape or flax and this was reflected in a milk with less unsaturated fatty acids.

In another experiment, in vitro, mammary gland cells were supplemented with acetic acid, BHBA, palmitic acid, stearic, oleic, trans vaccinia, linoleic, alpha-linolenic to evaluate the gene expression of SCD and PPaR. SDC was increased by acetic acid (as mentioned earlier, the importance of multi-fiber rations with less fermentable sugars) and reduced by oleic, linoleic and alpha linolenic acid, while the PPaRs did not show significant differences between the different treatments.

Acetic acid is able to increase the desaturation of fatty acids and the ex-novo synthesis of the same ones within the breast gland.

Thus it can be concluded that saturated LCFAs have little effect on SCD, whereas unlabelled LCFAs inhibit the gene expression of SCD. This is directly proportional to the number of double bonds. To increase the gene expression of SCD must be limited to the maximum of LCFA intake and instead increase the contribution of acetic acid.

In a word to increase desaturation of fatty acids, stearoyl Coa desaturase must be activated: this is achieved by promoting the production of acetic acid in the rumen, making fermentable fiber rations and reducing starch intake.

As mentioned earlier, morning reports focused on how to improve the acidogram of milk produced from beef, often at the expense of production.
Session II

The afternoon reports, on the other hand, studied the possibility of increasing milk production by activating peroxisomes.

The afternoon session was opened by Dr Mach of the University of Barcelona Studies. He recalled the role of lipid in dairy cattle and maintained that lipid metabolism in the breast was controlled at transcriptional level. That is, some fatty acids from partial ruminous biohydration may reduce the gene expression of certain fatty acid-producing enzymes and the activation of PPaRGs. This can lead to the development of methods to alter the fatty acidogram and increase its production. In addition, the gene expression associated with lipid metabolism may involve activation of the immune system at the breast, reducing susceptibility to milk mastitis (see also further on Savoini). It is hoped for a correct interpretation of the results to use a valid statistical work plan. All this led to the conclusion that the addition of 500 grams of dairy cow’s milk to dairy cows, increased production, increased fat and milk lactose but had no effect on the activation of milk peroxygen receptors.

The second report was held by prof. Savoini, of the University of Milan. It remembers the important biological value of goat’s milk and that this is due to its particular acidogram. The idea is to further increase its beneficial properties by enriching it with DHA and EPA, the omega-3 series. These fatty acids are essential in humans, as in all mammals, as they can not be produced by their precursors (if not in absent quantities) and have important cardio-protective properties.

The addition of fats to animal rations in production should not be considered as an important source of energy: lipids synthesize phospholipids, cholesterol, prostaglandins and other chemical mediators. The fatty acid metabolism plays an important role in immune cells. The most powerful immunomodulatory agents are in fact the PUFA, the omega-3 series and exclusively DHA and EPA. The ruminant liver showed a great ability to activate the oxidation of fatty acids in peroxisome unlike rodents. Fatty acids can in the liver activate the peroxisome to their oxidation, helping the liver to cope with the huge flow of NEFA during the transition phase, preventing and avoiding accumulation of fat in the same.

From the tests carried out, it is apparent that the addition of polyurethane EPA and DHA is able to increase the phagocytic activity of neutrophils and monocytes by modulating the immune response. Conversely, these polyunsaturated fatty acids are not capable of influencing the gene expression of PPaR while they are in monogastric.

Activation of peroxisomes by gene expression of PPaR is obtained in ruminants by the addition of palmitic acid.

The third exhibition was by Prof. Van Dorland of the University of Bern. His inception was peremptory and fatalistic: AT THE TOP OF THE LATEX, THE QUANTITY OF ENERGY AND PROTEIN REQUIRED FOR MILK PRODUCTION CAN NOT BE SATISFIED WHY THE INGESTION IS INSUFFICIENT. So it is inevitable that there is a mobilization of fat from reserve tissues: the NEFA peak is like the BHBA around 20 days while the lactation peak is at 50-60 days after delivery.

This is the Chuck (BURDEN) to pay for milk production. The ability to adapt to BEN is subjective: animals that produce the same amount in the same environment may have no pathologies or viceversa ketosis, mastitis, placenta dislocation etc. So everything has a genetic basis.

The aim of the research was to evaluate the dynamics of liver gene transcription on different subjects under the same physiological conditions. Hepatic biopsy was performed on 232 pluripotic frisons 3 weeks before delivery, 4 and 13 weeks after delivery.

From this immense work it emerged that cows that brilliantly exceeded the BEN period (not necessarily and always the most productive) were the ones that had the peroxisomes activated by PPaR transcription. This demonstrates the validity of the method and that activation of the same can bring enormous benefits to dairy cows.

The last report was from Dr. Leroy of the University of Merelbeke (BE). With great courage, he claims that adding fat to dairy cows in the first lactation period reduces fertility of the dairy cows. This is because they lead to an increase in milk production by sharpening the BEN of the same, reducing the size of ovarian follicles. It would be better to make these fats in steaming-up in order to reduce fat mobilization.

This led to a lively exchange of views during the final discussion between Leroy and van Dorland, which argued that if there is no chance of using the storage fat where the animal can take the energy?

This is to understand the spirit that animated the day, characterized by independent, non-sponsored theses of high technical and scientific level.



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