1 / 31

FEEDING FOR MILK COMPOSITION

FEEDING FOR MILK COMPOSITION. José Eduardo Portela Santos VMTRC – UC Davis. Milk Components. Fat Content Fatty acid profile Crude protein Content True protein vs NPN Lactose Minerals and vitamins. Several nutritional factors affect the composition of milk of dairy cows:

tricia
Télécharger la présentation

FEEDING FOR MILK COMPOSITION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. FEEDING FOR MILK COMPOSITION José Eduardo Portela Santos VMTRC – UC Davis

  2. Milk Components • Fat • Content • Fatty acid profile • Crude protein • Content • True protein vs NPN • Lactose • Minerals and vitamins

  3. Several nutritional factors affect the composition of milk of dairy cows: • Energy intake (Mcal of NEL) • Energy source • CHO • Lipids • Protein intake • Protein degradability and quality • Interactions between protein and energy • Amino acids • Minerals: Na, K (DCAD) • Feed additives (Niacin, fibrolytic enzymes)

  4. Milk Fat • Forage:Concentrate ratio • CHO: • NDF • Effective NDF • Physically effective NDF • Ruminal digestibility of NDF • NFC • Composition of the NFC: sugars, starch and pectin • Ruminal degradability of starch

  5. Ionophores • Fat supplementation • Lack of RDP (fiber digestibility and buffering effect) • Dietary buffers

  6. Theories • Low fat diets • Acetate deficiency • B-OH-butyrate deficiency • High rumen molar concentration of propionate: Insulin theory (glucogenic theory) • Vit. B12 deficiency • Trans fatty acids

  7. Mechanism of Action of Trans FA • Milk fat suppression: reduced SCFA (De Novo synthesis) • Trans fatty acids depress milk fat in 48 to 72 hs • Preliminary data from Maryland (Piperova et al., 1998): • Acetil CoA Carboxylase activity decreased (61%) • Fatty acid synthase activity decreased (54%) • Acetil CoA Carboxylase mRNA decreased (55%)

  8. Nutritional Causes of Milk Fat Suppression • Inadequate NDF • Inadequate physically effective NDF (particle size) • Poor NDF digestibility • Forage source: buffering capacity • Excessive amounts of NFC • Excessive amounts of RDS • High fat diets

  9. Fat sources with highly unsaturated FA profile • Yellow grease, oils • Interactions between fat source and forage source (binding sites) • Alfalfa hay vs corn silage • Protein supplements with high PUFA content • Fish meal, blends of marine by products • Lack of RDP (fiber digestibility & buffer effect) • Lack of buffers

  10. Milk Protein • NEL intake • Forage:Concentrate ratio • Amount of fermentable CHO (RDS) • Dietary CP level • Amino acid profile of the protein flowing to the duodenum • Dietary fat

  11. Effect of Grain Processing on Plasma Insulin P < 0.05 • Data from 832 blood samples from 32 cows (Santos et al., 2000)

  12. Diets with more fermentable energy increase milk protein: • Increase flow of microbial protein • increase molar concentration of propionate in the rumen • increase blood insulin

  13. Dietary Protein and Milk Protein • Low efficiency of N utilization for milk protein synthesis (< 30%) • Sprndly (1986): No relationship between dietary CP content and milk protein concentration • Emery (1978): correlation between dietary CP and milk protein content (r2=0.35) • The effect of higher CP diet is associated with greater DMI and total energy intake

  14. Dietary Fat and Milk Protein • Negative relationship between dietary fat and milk protein concentration • Independent of fat source • Increased efficiency of amino acid extraction • Supplying more fermentable CHO or high quality RUP partially overcomes milk protein depression

  15. Conclusions

More Related