We evaluated the chemical compositions of cassava pulp samples produced by four cassava starch factories at different locations in northeast Thailand and the metabolizable energy (ME) of the cassava pulp for cattle. There were significant differences in the P (0.03% ± 0.02%) and K (0.36% ± 0.2%) contents of the samples from different factories (p < .05). Moreover, we found interactions between factory and season in the neutral detergent fiber (36.02% ± 8.8%) and nonfibrous carbohydrate contents (59.33% ± 9.1%) (p < .05). For the evaluation of ME, a crossover-design experiment with four cattle maintained in each of two groups was conducted. There were two dietary treatments at a maintenance level of 1.27% body weight: (1) a control diet, and (2) a cassava pulp diet, containing the control diet at 70.2% and cassava pulp at 29.8% (dry matter [DM] basis). Feeding cassava pulp did not affect energy intake, energy loss, heat production, energy utilization efficiency (except for the urine-to-gross energy ratio), methane production, fecal N, or nutrient digestibility (except for crude protein digestibility). The total digestible nutrients, digestible energy, and ME contents of cassava pulp were 74.4%, 12.9 MJ/kg DM, and 11.3 MJ/kg DM, respectively.

The utilization of probiotics in livestock diets is increasing because it can result in improved productivity. Bacillus spp. are gram-positive spore-forming bacteria that are resistant to heat, cold, acid, and digestive enzymes (Carlin, 2011;Casula & Cutting, 2002). Although they cannot colonize the intestinal tracts of animals, they can have beneficial effects on productivity. Various studies have been conducted to clarify the effects of Bacillus spp. supplements. When supplied in pig feed, Bacillus subtilis LS 1-2 suppressed the levels of Clostridium spp. and Coliforms in the pigs' intestines and improved their growth performance (Lee et al. 2014). Broiler productivity was also improved by the addition of Bacillus subtilis UBT-MO 2 to their feed (Zhang et al. 2013). Sun et al. (2011) reported that the supplementation of Bacillus subtilis natto improved calf growth and development of the rumen. In lactating cows, supplementation with B. subtilis natto increased milk yields and the concentrations of propionic acid in the rumen (Sun et al. 2013). Supplementation with B. subtilis DSM15544 (B. subtilis C-3102) increased not only milk yields, but also milk protein levels, total solids, and milk energy secretion (Souza et al. 2017).These effects of B. subtilis supplementation in dairy cows were examined using Holstein-Friesians, which are farmed in cool temperate regions and are characterized as high-yielding and high feed intake cows. These characteristics lead to high heat production, accounting for 30% of the energy intake (Coppock, 1985). However, this high heat production makes the animals vulnerable to heat stress (Galán et al. 2018). On the other hand, in tropical regions such as Southeast Asia, crossbreeds between Holstein-Friesians and Bos indicus are mainly used in dairy production, even though they are less productive. These crossbreeds are suitable for tropical regions because B. indicus has a lower metabolic rate and is more resistant