Using 3.3 kg of each of the different mixtures produced between 18.50 and 16.94 kg green grass, which corresponded to 5.6–5.13 kg green grass from 1 kg mixture (Tables 1 and 2). The DM contents ranged from 10.8 to 14.40%. In the studies, between 6 and 10 kg green grass was produced from 1 kg grain containing 6.4 to 20.0% DM. The results of Dung et al. (2010) showed a yield of 4.7 kg green grass with 19.7% DM; those of Peer and Leeson (1985) showed a yield of 5.7 kg green grass from barley. Many factors, such as irrigation water quantity and quality, pH, seed preparation, seed quality and type, sowing density, ambient temperature, hygiene status, plant nutrients, and light, affect DM production. It has been reported that as a result of the use of energy reserves, oxidation, nutrient exchange, and nutrient synthesis, any increase in DM would not be possible during the 7-d germination process and DM losses would be between 7 and 64%. (Lewis and Chadwick, 1983; Chavan and Kadam, 1989; Sneath and Melntosh, 2003; Karaşahin, 2014).
One study has found that adding N-containing LF to the irrigation water of hydroponically produced barley fresh green feed had a positive effect on the accumulation of total N and organic N in all plants and in different plant components (Lewis and Chadwick, 1983). During germination, an increase in proteins is proportional to the loss of DM through respiration. Previous studies have shown that, from the fourth day of germination, the absorption of minerals and nitrates from the roots increased and the synthesis of N compounds from the seed carbohydrate reserves increased, which led to an increase in CP levels. The increase in proteins through DM loss was ~24% from day 4 to day 8 and was proportional to the loss of DM, and that one-half of this increase was a result of protein synthesis from the N absorbed from irrigation water. In addition, it has been reported that there were CP losses of 7–24% after the eight day, and that CP content could be approximated to the seed after the second day of germination (Sneath and Melntosh, 2003; Chung et al., 1989). Previous studies have reported that there was a 3% average increase in DM in 7-d fresh green feed compared to that in barley seeds (Peer and Leeson, 1985; Dung et al., 2010; Shaarif et al., 2013). The results of the study by Karaşahin (2014) showed 16.5–19.9% CP in grass 7 d after germination with different applications compared to that in barley seeds with 13.5% CP; however, in terms of total yield, these results reported CP losses from 4.7 to 21.58%. During 7 d of germination, proteins were metabolized by enzymes, yielding an increase in water-soluble proteins and amino acids (Nielsen et al., 1977; Pathirana et al., 1983; Chavan and Kadam, 1989). This conversion to albumin and globulins increases protein quality; however, in terms of ruminant feeding, whether within the structure of proteins, the total amount of N is more important than this increase because the microorganisms in the rumen break down the majority of high-quality proteins into ammonia.
With the addition of safflower seeds and their high oil content, substantial fat loss was observed during germination. During plant germination, oils re-metabolize into hydrolytic enzymes and essential fatty acids. Carbon, hydrogen, and oxygen molecules released as a result of the breakdown of fats are used in the synthesis of nutrients that are required for the formation of different parts of the plant. It has been reported that linoleic acid and oleic acid decrease; linolenic, palmitic, and stearic acids increase; and total lipid values decrease compared to those in seeds, although there was a rapid decrease until the fourth day of germination and a rapid increase from the fourth to the seventh days. In a study conducted on two safflower varieties, it was reported that fat content decreased from 58 to 45% in the first 72 h of germination (MecLeod et al., 1962; Peer and Leeson 1985; Kubicka et al., 2000; Öztürk et al., 2012; Tonguç et al., 2012). In hydroponics systems, it is believed that the seeds with a high amount of fat, such as safflower seeds, will experience fat losses because of the amount of irrigation water and the frequency of irrigation during germination.
Different studies have reported that ADF value increased between 214.3 and 402.8% in barley fresh green feeds produced using different systems (Cuddeford, 1989; Shaarif, 2013). In particular, it has been reported that the starch contained in the seed is metabolized by enzymes and used in the synthesis of structural carbohydrates, such as cellulose and hemicellulose, thus increasing the amount of ADF with germination. The use of fats in the structure of the seeds and cell wall material explains the increase in ADF yield when the ratio of safflower is increased in the mixtures (Table 4).
Sharif et al. (2013) reported that the results of several studies indicated that the NDF values in fresh green feeds were 57.4–138.6% lower than those in the seeds. The NDF values of the products increased when the vetch and safflower ratio in the mixtures with no LF increased (Table 1). In the mixture groups with LF, the use of vetch increased NDF; whereas, the use of safflower decreased it (Table 2). It can be argued that the decrease in NDF in all mixtures compared to that in the seeds indicates increased intracellular material, which also indicates an increase in the digestible parts of the intracellular material (Tekce and Gül, 2014).
Different researchers and different production systems have reported ash values in barley fresh green feeds that ranged from 3 to 4.6%. (Bulletin, 1917; Peer and Leeson, 1985; Dung et al., 2010; Sharif et al., 2013; Akbağ et al., 2014). Similarly, in the present study, the ash content in all mixtures changed by 3.12 to 4.05%; however, DM losses were also observed. It is believed that the minerals found in the structure of the seeds are metabolized by enzymes, become water soluble, and are washed away by irrigation water during the germination period.
Several studies have shown that vitamin values in seeds increase with germination, but these increases can be minimal (Chavan and Kadam, 1989). Cuddeford (1989) has reported that the amount of carotene is 4.1 mg/kg DM in barley seeds and 42.7 mg/kg DM in 6-d-old fresh green feeds. In other studies, it has been reported that the carotene content increases with germination (Leontovich and Bobro, 2007) in low-carotene rice, wheat, and corn as a result of 7-d germination, with an approximately 10-fold increase in rice and wheat and a >50% increase in corn (Chattopadhyay and Banerjee, 1951). The amount of β-carotene increased by 4- to 6-fold as a result of seed germination in soybeans (Young et al., 2012; Lee et al., 2013).
Previous studies have reported that the losses of protein and vitamins are minimized with germination compared with that of other conservation methods (Leontovich and Bobro, 2007). As a result of 6-d germination, vitamin E increased from 7.4 mg/kg DM to 62.4 mg/kg DM, and it was observed that within a few days of germination, vitamins can increase by up to 20 times (Cuddeford, 1989). As a result of 2-d germination, α-tocopherol significantly increased in rice and wheat seeds (Öztürk et al., 2012; Kim et al., 2017). The addition of vetch to the barley reduced the amount of oil in the seed mixture compared to that in barley alone, but with germination, this was more advantageous in terms of vitamin E than the fat-rich safflower mixtures. In the present study, adding vetch and safflower to barley reduced vitamin E production.