پژوهشهای علوم دامی ایران (Aug 2021)
Effect of Calcium Salts of Fatty Acids on Performance and Milk Fatty Acids Profile in Holstein Cows
Abstract
Introduction[1] Cows need a lot of energy to produce milk in early lactation. Due to the low dry matter intake in this period, it is necessary to increase diet energy concentration. Therefore, fat supplements are often used to increase the concentration of metabolizable energy for reduce mobilization of adipose tissue in fresh cows. Many studies shown that adding fat to diet of lactating cows, improves milk production and increases lactation persistency. Increasing milk yield by 2 to 10 percent was reported in cows receiving fat supplement compared to control. One of the limitations of using fat supplements for ruminant is its negative effects on digestion of fiber. In some studies, using of unprotected fat sources reduced digestibility of fibers and milk fat percentage in early lactation. In contrast, some researchers have reported that adding protected fats to the diet of lactating cows increased milk production and had not negative effect on milk fat. The reason for this was minimum effect of protected fat on ruminal fermentation. Usual protected fats include crystalline or prilled fatty acids, formaldehyde treated protein encapsulated fatty acids, hydrogenated lipids, fatty acyl amides and calcium salts of fatty acids. Calcium salts of fatty acids are lower degradable than other fat sources in rumen. More studies should be done because of the low production of calcium salts of fatty acids in Iran and as well as the demand for better quality of fat supplements.Materials and Methods Twenty one Holstein cows were used under days in milk 30±8.5 with body weight 573 ± 69.4. The cows were divided into three groups (3primiparous and 4 multiparous) and were offered following rations for 100 days period:1- control (without fat supplementation), 2- ration containing fat supplement A (laboratory made for this research in Bu-Ali Sina University), 3- ration containing fat supplement B (Persia fat, Kimia Danesh Alvand Co, Tehran, Iran). Diets were designed to be iso-nitrogenous. After morning milking and before feeding, cows were weighed and body scored in 30, 70 and 100 days in milk. The cows were milked three times daily. The TMR was fed at 0530, 1430 and 2230hours daily. Feed intake and milk yield were recorded daily and weekly sampling was performed to determine milk, feed and feces compositions. Milk samples were analyzed for protein, fat and lactose. Feed and feces samples were analyzed for DM, Ash, CP, ether extract and ADF. Digestibility of ration nutrients was determined using acid insoluble ash as an indigestible marker. Blood samples were withdrawn on 45, 70 and 100 days in milk. Blood samples then were centrifuged at 4 ºC and 3000×g for 15 minutes. Then plasma was analyzed for glucose, cholesterol, triglyceride and non-esterified fatty acids. At the end of the experiment milk samples were collected to determine milk fatty acids profile. The fatty acids were determined using a direct method for fatty acid methyl ester synthesis using a gas chromatograph. Data were analyzed as a completely randomized design using the MIXED procedure of SAS. Results and Discussion in this study using fat supplements had not effect on BCS. Dry matter intake was not affected by diets. Milk production were higher in cows receiving fat supplement A than control while was not different compared to fat supplement B. milk production increased significantly after two weeks. During the treatment period, control increased milk fat percentage. Milk fat increasing was started in second week of experiment. The amount of milk lactose increased due to the milk production increasing in cows receiving fat supplement compared to control. FCM was not different between treatments. In this study, fat supplement A and B increased blood cholesterol. Amount of triglyceride increased but was not significant. NEFA and glucose were not affected by diets. C14:0, C14:1 and C18:2 were influenced by rations. Percent of C8:0 was higher in control than other treatments by 16 percent, it was not significant. Percent of C18:1 was higher in cows receiving fat supplement A and B than control, but was not significant. Rations had not affected on nutrients digestibility.Conclusion according to the results, fat supplement A can be used as fat source in early lactation.
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