A ten-week trial was conducted to evaluate the enhancement of production performance and nutrient utilization of laying hens through augmenting energy, phosphorous, and calcium deficient diets with fungal phytase (Trichoderma reesei) supplementation. 720 Hy-line Brown hens aged 28 weeks were randomly divided into 5 groups; each group had 8 replicates of 18 hens. Five experimental diets were prepared and fed to corresponding groups. A positive control (PC) diet contained 3.50% of calcium (Ca), 0.32% of non-phytate phosphorus (NPP), and apparent metabolic energy (AME) of 11.29MJ/kg, while a negative control (NC) diet contained 3.30% of Ca, 0.12% of NPP, and lower AME of 300 kJ/kg. The other three diets were supplemented with 250 FTU/kg phytase (PHY-250), 1000 FTU/kg phytase (PHY-1000), and 2000 FTU/kg phytase (PHY-2000) in addition to a regular NC diet. Results indicated that the positive control (PC) diet group had higher body weight gain, egg weight, and average daily feed intake. However, laying rate, egg mass, and FCR were most improved in the PHY-2000 group, followed by the PHY-1000 and PHY-250 groups (p < 0.05). Improved yolk color was most notable in laying hens fed the diet with PHY-1000 as opposed to the PC and NC groups (p < 0.05), but no overall difference was found among all of the phytase treated groups. The apparent availability of dry matter, energy, phosphorus, and phytate P was significantly higher in the PHY-2000 group than in the PC and NC groups (p < 0.05). Compared to the PC group, nitrogen retention was significantly higher in the PHY-1000 group, while calcium availability was higher in the PHY-250 group. The results suggested that the addition of phytase to diets with low P, Ca, and AME improved laying performance and apparent availability of dietary nutrients. Thus, it was concluded that the laying hen diet could be supplemented with 1000–2000 FTU/kg phytase for improving laying production and nutrient availability and mitigating the negative impact of reduced nutrient density in laying hen diets.

Background and Aim: Enteric methane emissions from ruminants contribute substantially to greenhouse gas accumulation and energy loss in livestock systems. In maritime regions such as Indonesia, macroalgae and seagrass represent abundant but underutilized bioresources with potential antimethanogenic properties. This study evaluated the effectiveness of Sargassum cristaefolium, Sargassum crassifolium, and Enhalus acoroides as feed additives for improving rumen fermentation characteristics and mitigating methane production in vitro. Materials and Methods: A completely randomized factorial design was employed using three marine plant species and four inclusion levels (0%, 5%, 10%, and 15%) with six replicates. Parameters assessed included dry matter degradation (DMD), organic matter degradation (OMD), pH, ammonia nitrogen (NH₃), volatile fatty acids (VFA), gas production, methane (CH₄), and microbial protein synthesis. Proximate, Van Soest, and phytochemical analyses were performed to determine nutritional composition and bioactive compounds. Data were analyzed using analysis of variance followed by Duncan’s multiple range test. Results: All three species exhibited favorable nutritional profiles and contained bioactive compounds, including tannins, flavonoids, and saponins. Supplementation at 10% significantly enhanced DMD, OMD, NH₃, VFA, gas production, and microbial protein synthesis (p < 0.05), with S. cristaefolium demonstrating the most pronounced effects. Rumen pH remained within the optimal physiological range (6.60–7.01) across treatments. Methane production decreased significantly at 10% inclusion, with reductions of 39.86%, 29.30%, and 23.92% for S. cristaefolium, S. crassifolium, and E. acoroides, respectively. Although 15% inclusion yielded greater methane suppression, it adversely affected fermentation efficiency and digestibility parameters. Projections indicated that adopting 10% supplementation could reduce methane emissions in North Sumatra Province from 5,286,097,238 kg to 3,645,821,265 kg by 2050. Conclusion: Supplementation with S. cristaefolium, S. crassifolium, and E. acoroides at 10% optimizes rumen fermentation while effectively mitigating methane emissions. These findings highlight the potential of marine biomass as a sustainable feed additive for improving livestock productivity and environmental performance. Further in vivo studies are warranted to validate long-term efficacy and practical applicability under field conditions. Keywords: enteric methane mitigation, in vitro fermentation, marine biomass, methane emissions, ruminant nutrition, Sargassum crassifolium, Sargassum cristaefolium, Enhalus acoroides.