عنوان مقاله [English]
Introduction: Flax products (seed and meal) are one of the sources of energy and protein for ruminants. Although flaxseed is a very inexpensive and affordable source of omega-3s, more than 50% of its fatty acids are made from alpha-linolenic acid, but it cannot be used at high levels due to its anti-nutritional properties. Flaxseed processing improves nutrient consumption while reducing the negative effects of anti-nutritional substances such as lintine and making food more palatable. Various methods are used to process and improve the flaxseed digestion process, such as micronization and extrusion. The extrusion process is the process of processing high-temperature materials in a short time and is done by a combination of moisture, heat, mechanical energy, and pressure. Extrusion is also a technical function by which feed is processed, extruded, and cooked under a constant increase in pressure and then expanded due to a sudden pressure drop. Heat treatment applied during the extrusion process reduces the access of rumen bacteria to the fat in the diet by denaturing the protein matrix around fat droplets in oilseeds such as flaxseed and thus can reduce fatty acids. Microwave by microwave can be done after adding 25% moisture to the grains for three minutes in a device containing an infrared lamp. It was also found that micronization could be used to increase the degradable protein content of the rumen. This study was performed to evaluate the effect of flaxseed level and processing method on performance, skeletal growth indices, health, and ruminant behavior of suckling calves.
Materials and methods: In this study, to investigate the effect of using different levels and methods of flaxseed processing on the performance of suckling calves, 35 newborn Holstein male calves with an initial weight of 41±4.5 kg were used. This experiment was performed in a completely randomized design with seven treatments and five replications. Treatments included: 1. Control, 2. The treatment contained 5% of raw flaxseed, 3. The treatment contained 10% of raw flaxseed, 4. The treatment contained 5% of micronized flaxseed, 5. The treatment contained 10% of micronized flaxseed, 6. The treatment contained 5% of extruded flaxseed, and 7. The treatment contained 10% of extruded flaxseed. The total trial period was 60 days, which included 14 days of adaptation. Stool consistency scoring was considered as a daily livestock health indicator for each calf. Measurement of skeletal growth rate was done by meter and caliper at the beginning and end of the period. To evaluate the effect of experimental treatments on calf performance, dry matter intake, daily weight gain, and feed conversion ratio were also measured.
Results and discussion: Experimental treatments had no significant effect on daily feed intake, daily weight gain, and feed conversion ratio. Also, the growth of skeletal indices, fecal consistency, and rumination behavior was not affected by experimental treatments. The lack of effect on food intake probably indicates that the amount of linseed fatty acids used has a minimal mechanism of short-term regulation of feed intake. Oily seeds such as flaxseed contain eicosapentaenoic and docosahexaenoic fatty acids, both of which are active derivatives of linolenic acid. It is known that these oxygenated metabolites play an important role in the growth and development of infant animals, especially the development of their nervous system. However, eicosapentaenoic and docosahexaenoic fatty acids may have a lower effect on feed efficiency during this period of calves' life. In general, the duration of chewing is reduced by decreasing the size of particles and the content of insoluble fibers in neutral detergent. The lower content of insoluble fibers in the neutral detergent and its chemical and physical nature may have reduced rumination and chewing activity. Probably, the changes in the rumination time may be related to the difference in the dry matter consumed and the digestibility of the nutrients, and the rumination activity can also be considered a factor to diagnose rumen health due to the stimulation of saliva secretion. The duration of chewing activity (sum of eating and ruminating) can be a good measure of rumen health.
Conclusions: According to the results of this study, the use of processed flax did not hurt the performance, skeletal growth indices, and health of calves. Extruded and micronized flax can be used at the 10% level in the diet of suckling calves as a source of protein and energy.