Document Type : Research Paper
Authors
1 Department of Animal Science, Faculty of Agriculture, Uremia University, Urmia, Iran. E-mail: ah.rezakhani@areeo.ac.ir
2 Corresponding Author, Department of Animal Science, Faculty of Agriculture, University of Tehran, Karaj, Iran. E-mail: rezayazdi@ut.ac.ir
3 Department of Animal Science, Faculty of Agriculture, Uremia University, Urmia, Iran. E-mail: y.alijoo@urmia.ac.ir
Abstract
Introduction The beginning of lactation is one of the important performance signs related to health, fertility and production in lactating cows. Meeting the energy needs is considered as the main challenge of lactating cows at this period. Increasing the mobilization of body fat is one of the ways to meet the lack of energy, which can lead to an increase in the supply of non-esterified fatty acids (NEFA). Therefore, management strategies based on nutrition can play an important role in increasing energy intake and minimizing negative energy balance (NEB). The use of fat supplements can be considered as an effective solution to increase the amount of energy in the diets of fresh cows. The objective of this study was to evaluate the effect of feeding different fat supplements containing saturated and unsaturated fatty acids on production performance, blood and rumen parameters in fresh Holstein cows.
Materials and Methods In this study, 32 Holstein cows with average live body weight 649.2 ± 29.11 kg and body condition score of 3.78 ± 0.30 were used after calving for 21 days in a completely randomized design in four experimental groups. Experimental treatments included: 1) control: no fat supplement, 2) unsaturated: containing calcium salt of unsaturated fatty acids, three percent based on DM, 3) saturated: containing calcium salt of saturated fatty acids, three percentage based on DM and 4) mixed: contained an equal mixture of both types of fat supplements. Dry matter intake (DMI) was measured daily. Cows were milked three times a day at 05:00, 13:00 and 21:00 in a parlor and milk yield was recorded. Milk was sampled at each milking on days 7, 14 and 21 until analyzed for fat. Body weight was measured on days 7, 14 and 21 after parturition. Blood samples were collected from subcaudal vein with vacuum tubes containing anticoagulant heparin on days 0, 7 and 21 after parturition. After separating the serum using a centrifuge, for the measurement of glucose, triglyceride, cholesterol, NEFA and beta-hydroxybutyrate (BHBA), samples were sent to the laboratory. Ruminal fluid is collected on the d 21 after parturition, two to three hours after morning feeding by the esophageal tube and using a suction pump, and after passing through the filter and measuring the pH by a portable pH meter, was sent to the laboratory to measure volatile fatty acids (VFA).
Results and Discussion The results of the study showed that the calcium salt of unsaturated fatty acids caused a decrease, and the calcium salt of saturated and mixed fatty acids caused an increase in DMI compared to the control treatment. Milk production, milk fat percentage, 4% fat corrected milk production, energy corrected milk production, feed efficiency, blood concentrations of glucose, cholesterol, triglyceride and BHBA values, as well as rumen fermentation parameters were not affected by the treatments. The concentration of NEFA in the plasma, in the control treatment and the treatment containing calcium salts of unsaturated fatty acids, were measured above the safety margin provided for sub clinical ketosis.
Conclusion According to the lactation performance of cows, the absence of problems regarding the amounts of NEFA and BHBA as indicators of metabolic disorders and the ineffectiveness of supplements on rumen fermentation parameters, it seems that it is possible to use an equal mixture (50:50) of fat supplements of calcium salts containing saturated and unsaturated fatty acids in the diet of fresh dairy cows in the amount of three percent.
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