Document Type : Research Paper

Authors

• Hamidreza Taghian ¹
• Mehdi Dehghan banadaky ²
• Kamran Rezayazdi ³
• hamed Khalilvandi-Behroozyar ⁴

¹ Department of Animal Science, Faculty of Agriculture and Natural Resources, University of Tehran Karaj, Iran.

² Department of Animal Science, Faculty of Agriculture and Natural Resources, Tehran University, Karaj, Iran.

³ Department of Animal Science, Faculty of Agriculture and Natural Resources, University of Tehran , Karaj, Iran

⁴ 4. Department of Animal Sciences, Faculty of Agriculture, Urmia University, Urmia, Iran

Abstract

Keywords

• emulsifier
• bile powder
• lecithin
• fat
• dairy cow
• digestibility

Main Subjects

• Animal Nutrition and poultry

Extended Abstract

Introduction

    The addition of fat supplements to the diet of dairy cows is a commen method to increase the energy content of the ration. Protected fats have been developed commercially, which are normally based on saturated fatty acids like palmitic acid (C16:0) and stearic acid (C18:0). The micelles are necessary for the digestion of lipids because they contain a mixture of bile acids and salt, lecithin, lysolecithin, monoglycerides, cholesterol, and fatty acids, which are necessary for the absorption of lipids into intestinal cells. The ability of pancreatic lipase, colipase, and phospholipases to efficiently digest triglycerides and phospholipids in the diet of ruminants requires the presence of bile salts and lysolecithin to engender emulsifying properties and micelle formation. Lysolecithin is a potent emulsifier that is produced from the enzymatic hydrolysis of lecithin and facilitates the digestion of fatty acids. Bile salts play a role as an emulsifier and facilitate the digestion and absorption of fats and fat-soluble nutrients. Particle size and physical form of saturated fat supplements have been suggested as an effective factor on fatty acid digestibility and production responses in dairy cows. At this moment, there is no study that has investigated the effects of augmenting emulsifying compounds such as lecithin or bile powder to fat supplements with different particle sizes on blood parameters and the digestibility of nutrients in the digestive tract of high-producing Holstein dairy cows. Therefore, the present research has investigated the effect of the physical form of the saturated fat supplement containing lecithin or bile powder on the digestibility of nutrients and some blood parameters in Holstein dairy cows.

Material and method

    48 lactating Holstein cows (lactation: 130±21; milk production: 38.4±1, weight: 590±12) during two experimental periods (24 cows in each period) in a 2x3x2 completely randomized factorial design used and were randomly grouped into 6 experimental treatments by using silver saturated fat supplement (Kimia Danesh Alvand ^©, Qom, Iran): 1. Control diet + 2.5% granulated fat supplement, 2. Control diet + 2.5% granulated fat supplement containing 5% lecithin 3. Control diet + 2.5% granulated fat supplement containing 5% bile powder 4. Control diet + 2.5% Flaked fat supplement 5. Control diet + 2.5% Flaked fat supplement containing 5% lecithin and 6. Control diet + 2.5% Flaked fat supplement containing 5% bile powder. All the experimental diets were balanced to have the same amount of nitrogen and energy and met the nutrient requirements of the animals according to the recommendations of the National Research Association. To prepare the bile powder, the gallbladders were collected from the slaughtered and transferred to the laboratory, then homogenized and filtered through nylon filters, and then the bile powder was obtained by drying at 60^°C for 24 hours. After the analysis of DM and nutrient content in the feed and feces samples, the apparent digestibility was determined by using the internal indicator of acid-insoluble ash. In order to evaluate plasma parameters, including glucose, triglyceride, cholesterol, high-density lipoproteins, low-density lipoproteins, total protein, albumin, urea, AST, ALT, NEFA, and BHBA the BT1500 ELISA was used. Eventually, all test data were analyzed by using SAS statistical software and MIXED procedure.

Results and discussion

   The digestibility of total fatty acids, 16 and 18 carbon of fatty acids increased in treatments fed with fat powder containing additives (lecithin or bile powder) (P≤0.05). Feeding fat supplements containing lecithin or bile powder increased plasma concentrations of NEFA, triglycerides, cholesterol, high-density lipoproteins, and very low-density lipoproteins (P≤0.05), but had no effect on other plasma parameters including total protein, albumin, and urea, low-density lipoprotein, and BHBA. The increase in the digestibility of fatty acids in lecithin and bile powder groups has led to an increase in the plasma concentration of NEFA, triglyceride, HDL, VLDL, and cholesterol.

Conclusion

    Adding emulsifying ingredients to bypass saturated fat supplements in the diet of dairy cows increases the absorption of fatty acids, especially palmitic, and stearic acids. Moreover, saturated fat supplements containing lecithin or bile increase the plasma concentration of some blood parameters such as triglycerides, cholesterol, HDL, VLDL, and NEFA.