Two types of modified nano-montmorillonite (MNM) were developed by ion-exchange reactions using two different surfactants; sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CETAB), to prepare MNM_SDS and MNM_CETAB, respectively. Both MNM types were on the nano-scale and had higher cation-exchange capacity values than NM clay. The MNM_CETAB had the highest zeta potential (−27 mV) compared with the other clays. Effects of MNM types on in vitro ruminal batch culture fermentation, nutrient degradability, and methane (CH₄) emission compared with monensin were evaluated in vitro using a semi-automatic gas production system. The experimental treatments were the control (0 supplementations), monensin (40 mg/kg DM), and NM (5 g NM/kg DM), and two levels of MNM_SDS and MNM_CETAB were supplemented at 0.05 (low) and 0.5 (high) g/kg DM to the control basal feed substrate. Among the experimental treatments, the high dose of both MNM types reduced (p < 0.01) CH₄ production and ammonia concentrations compared with the control, while only MNM_CETAB treatment tended to increase (p = 0.08) the truly degraded organic matter compared with monensin. All MNM treatments increased (p < 0.01) acetate molar proportions compared with monensin. The high MNM_CETAB increased (p < 0.01) the in vitro ruminal batch culture pH compared with the control and monensin. The MNM_CETAB supplemented at 0.5 g/kg DM is the most efficient additive to reduce CH₄ emission with the advantage of enhancing the in vitro nutrient degradability of the experimental feed substrate. These results indicated that MNM could modulate the in vitro ruminal fermentation pattern in a dose- and type-dependent manner.

The study tries to determinate the most important problems that facing fish farming farms in Egypt. The study aims to achieve many objectives: studying total and marine fish production approach and its species (2012-2018), study the problems faced farms for the season (2019/2020), through a questionnaire of 90 farms on the Egyptian northern coast. Results indicate to that the natural fisheries Egypt have a reducing production depends on fish farming to meet consumption needs, including marine species, especially with the current scarcity of fresh water resources. The production functions and costs estimated with their total, average and marginal Functions, The amount of lost income was also determined due to the failure to synthesize the available farm resources at the optimal level/ the maximum level of the profit. The most important finding is the difficulty of providing the natural pretext and permission to purchase them at the right time (Somewhat appropriate). Also, the failure of General Authority for Fish Resources (GARFD) to clear public gates (often and permanently), the lack of security services for farm owners Fish (often throughout the year), the increase of summary value of the farm imposed by the Public Authority for Fish Resources on the owners of marine fish farms to (some extent and often). As well as the increase in the summary value of the farm imposed by the (GAFRD) on the owners of marine fish farms (permanently), and the lack of electricity or Availability of fuel on marine fish farms, (on a permanent basis).