Napier grass is the newest economics crop of the farmers in Nong Wua So district, Udon Thani Province. A study in costs and revenues of Napier grass farmers in Nong Wua So district Udon Thani Province. Because there and nearby have a lot of animal husbandry and Napier planting. The objectives of the study are 1) to study the general condition of Napier grass farmers in Nong Wua So District Udon Thani Province. 2) to investigate costs and returns of Napier grass farmers in Nong Wua So District Udon Thani Province and 3) to analyze problems and obstacles of Napier planting and find a solution to solve the problem by choosing to study in the farmers who are Napier planting in Nong Wua So district, Udon Thani Province. Sampling by using a specific method (Purposive Samplings) for 54 cases, the production results in 2021 were analyzed as follows from the study of the average cost per hectares of Napier grass farmers in Nong Wua So district, Udon Thani Province for the production year 2021 found that the average total cost all sizes of cultivated areas equal to $105/hectares which are divided into average variable cost was $97.4/ hectares and the average fixed cost was $7.63/hectares. when considering by the size of the cultivated area it was found that small planting areas (1-3 hectares) had average total costs of $126.53 /hectares, which consisted of average variable costs are equal to $116.76/hectares and the average fixed cost is $9.76/ hectares. The medium-sized planting area (3.1-5 hectares) has an average total cost of $93.97/hectares consisting of an average variable cost was $84.22 / hectares while the average fixed cost was $9.76/hectares. For large planting areas (more than 5 hectares) the average total cost is $83.23/hectares which consists of the average variable cost of $79.0 /hectares and the average fixed cost is $4.19/hectares. The revenues of Napier grass farmers production year 2021 from the study found that all size of Napier grass cultivation areas has the average income was $205.16/hectares, the average cost was $105/hectares and net profits was $100.16/hectares. when the researchers considering by the size of the cultivated area it was found that small planting areas (1-3 hectares) had an average income of $229.35/hectares, an average cost of $126.53/ hectares, and an average net profit of 102.82/hectares. The medium-sized with an average income of $196.18/hectares, an average cost of $93.97/hectares, average net profit of $102.21/ hectares and the large planting areas had an average income was $189.93/hectares and the average cost was $83.23/hectares, average net profit equal to $106.7/hectares. The obstacles of Napier grass farmers production in Nong Wua So District Udon Thani Province. The Napier grass farmers were facing a production problem about animal and pests that often destroy packaging after silage are produced, as well as storage and transportation problems for commercial and marketing purposes. In addition, because the number of farmers who grow Napier grass is not many and the planting area is not enough, causing the amount of food to be insufficient, it must be ordered or imported from the area or other producer groups. have higher production costs.
There were interaction (Pa$?0.05) between cultivars and feed types on CP, potential gas production (A+B), metabolisable energy (ME) and degradation rates (C). The CP content of Common, Red and Dwarf Napier increased numerically due to ensiling process. Nevertheless, the ME content and C value declined gradually after the ensiling process. The compaction during ensiling process could affect the quality of Napier cultivars in particular the IVDMD and the degradation rates due to leaching of nutrient. It is concluded that the nutritive value of Napier cultivars were generally decreased due to preservation mechanism. Despite, the CP content and total gas production of Common Napier increased significantly after ensiled.

Forages are essential in animal production systems hence the most important feed as a substitute for concentrates normally used for feeding livestock. In fact, forages were certainly known as a cost effective feed rather than commercial concentrate. The substitution of forage to concentrate from 30 to 70% in dairy cattle diet could reduce up to 30% cost of production (Sanh et al., 2002). Guinea and Napier are the common cultivated grasses species in Malaysia. Guinea grass yielded from 9 to 12 tonnes dry matter yield (DMY) ha-1 cut-1 with cumulative mean more than 20 tonnes ha-1 yr-1(Ahmed et al., 2012; Munyasi et al., 2015). Besides, the Napier grass tends to produce higher dry matter yield and surpass most other tropical grasses with yield of 70 tonnes ha-1 yr-1 (Wijitphan et al., 2009). Napier grass was first introduced to Malaysia in the 1920's, since then many cultivars had been introduced in Malaysia, namely as Common Napier, Red Napier, Taiwan Napier, Dwarf Napier, Dwarf Mott, Australian Dwarf, Indian Napier, Uganda Napier, Zanzibar Napier, Kobe Napier and King grass (Halim et al., 2013;Haryani et al., 2012). Several comparative studies on the effect of harvesting age showed that the optimal harvesting ages of Napier grass were within 5 to 9 weeks old (Zailan et al., 2016; Lounglawan et al., 2014).Repeated cuttings at shorter interval will reduced the cumulative DMY whereas prolonged harvesting age will reduced the quality of the grasses. The tropical grasses tend to reach its maturity faster, become fibrous and lignified compared to temperate grass. Moreover, leaf fraction which is more digestible and nutritious compared to stem declined as the species advanced towards maturity (Mustaque et al. 2010). Therefore, silage is most suitable method in preserving the nutritional quality of Napier grass within the optimum harvesting ages.Napier grass grows best in high-rainfall areas not less than 1200mm rainfall yr-1 but it does not tolerate flooding (Legel, 1990). The estimated area prone to flood disaster is 9% of total area in Malaysia (D/iya et al., 2014). In spite of flood, tropical countries are more vulnerable to drought compared to temperate countries and therefore, the conservation of feed is crucial to preserve the quality and supply adequate feed to livestock. Silage was found to be more suitable than hay making process because of high relative humidity, more than 90%, will easily spoil the hay. In an attempt to preserve the nutritional quality, especially protein content, the changes in nutritive value of grasses during ensiling process need to be assessed. The conservation of Napier grass among the plentiful tropical forages is preferable due to its high forage yield and favorable concentration of soluble carbohydrates in providing good fermentation condition. However, at early harvesting age, when it presents a promising nutritive value, the high moisture, high buffer power and the low sugar concentration can result in low quality silage. The presence of topsoil layer during fodder harvesting might introduce the undesirable microorganism during ensiling, mainly clostridia. Proliferation of clostridia may appear under specific circumstances of low water soluble carbohydrates in conjunction with high moisture and temperature. The presence of clostridia in silage has reduced digestibility and intake characteristics and increases the incidence of metabolic disturbances in animals to which they fed (Yeruham, et al. 2003).In an attempt to produce good quality silage, 35 to 40% dry matter content and at least 2% of sugar content in feed materials were required as recommended by Ohmomo et al. (2000). Increase in dry matter content of silage, particularly by wilting technique benefits both environmental and nutritional value of silage. Moreover, the breakdown of protein content by plant protease cease by increasing the dry matter content (Soderlund, 1995). The optimum pH for protease activity is between pH 4 to 8. Proteolysis and growth of spoilage microorganism can be inhibited by reducing the pH value. Thus, the quality of silage depends on the harvesting age, nutritional composition before ensiled and the method of ensiling.Hence, the general objective of this study was to evaluate the yield and nutritive value of four Napier (Pennisetum purpureum) cultivars as fresh and ensiled fodder.