A new animal calorimeter using a ventilated hood was constructed in Thailand. The recovery rates of our head cage were 96.5%, 97.0%, 95.7%, and 101.8%. The recovery rates of our head cage (95.7 101.8%) are reliable compared with Japanese whole-body chambers. The 99% CO 2 recovery time of our head cage was an average 14 min. It was shorter than whole-body chambers because of smaller effective volume and higher flow rate. Our head cage system excels at dynamic measurement of heat production. We started accumulating data concerning the energy value of Pangola grass (Digitaria eriantha) using 4 Brahman steers (body weight, 372.8 34.4 kg, mean standard deviation; age, 3 years old). They were fed Pangola grass for 21 days; the grass was harvested approximately 45 days after cutting in several farms around Bangkok. Digestible energy and metabolizable energy of Pangola grass hay in our study were 10.28 and 7.99 MJ/kg dry matter. The average volume of methane production was 228.3 L/day and energy loss in the form of methane was 0.097 of the gross energy intake. These values are acceptable when compared with those obtained when low-quality tropical feed is provided to the steers. Discipline: Animal industryAdditional key words: Brahman steers, digestible energy, metabolizable energy

Metabolism trials were conducted on six wethers and four Brahman steers given Ruzi grass hay with different levels of soybean meal in order to compare the effects of protein levels on energy and nitrogen balances, and fiber digestion between the two animal species. Crude protein (CP) contents in four dietary treatments were 3.4%, 6.9%, 10.4%, and 13.9% with the different levels of soybean meal supplement. Digestibilities of crude fiber, neutral detergent fiber and acid detergent fiber were greatly improved in sheep by the supplement of soybean meal until the CP content in the whole ration reached 10%. The difference was more than 10 units in each fiber fraction. While in cattle, fiber fraction digestibilities in the animals given Ruzi grass hay without soybean meal supplement were relatively high. The values were then improved by the smallest amount of supplement (6.9% CP). Beyond this level, there was no effect of the supplement. Although digestibility of CP was lower in sheep when no protein supplement was given, it was higher in sheep when high protein diets were given (10.4 and 13.9% CP). The total digestible nutrient and digestible energy contents well represented overall features of the differences in nutrient digestibilities between sheep and cattle. With lower levels of soybean meal supplement, these values were lower in sheep than in cattle. While, with higher levels of the supplement, there was no difference in the values between the animals. Sheep are often studied as a model animal for cattle in order to examine nutritive value of feed resources. It was suggested in the design of feeding trials using sheep, that CP content of whole ration, in which a target feed resource is included, should be more than 10%. Discipline: Animal industryAdditional key words: fiber digestion, protein supplement JARQ 41 (3), 253 -260 (2007)

A metabolism trial was conducted with four Brahman cattle and four swamp buffaloes fed with Ruzi grass hay (Brachiaria ruziziensis, 0.77% N). There was no significant difference in energy and nitrogen balances, and nutrient digestibilities between cattle and buffaloes. However, fasting heat production was significantly lower in buffaloes. Urinary excretion of allantoin tended to be lower in buffaloes than in cattle although there was no significant difference. Free fatty acid content in the blood serum during the fasting period was lower in buffaloes than in cattle although it was not different when the animals were fed. On the other hand, urea content in the blood serum during the fasting period was higher in buffaloes than in cattle.

The use of chopped sugarcane stalk (CSS) as a roughage for lactating cows was examined using four Holstein crossbred cows in a private dairy farm in Khon Kaen, Thailand, in comparison with rice straw (RS), which is the conventional roughage in the dry season in the region. Cows were subjected to the following two dietary treatments: Diet 1) RS with commercial concentrate feed, and Diet 2) CSS and RS with commercial concentrate feed. The diet was switched over every 3 weeks. The amount of concentrate was determined by the experience of the owner of the cows. RS and CSS were given ad libitum. There was no difference in milk production between two groups, although the total DMI was less in cows fed CSS. Solid-not-fat (SNF) content in milk was significantly higher in the cows given CSS. The NEFA content was significantly lower in the animals given CSS, which suggested that cows given only RS as roughage would be suffering from energy malnutrition. Therefore, it was considered that CSS feeding improved energy supply, which resulted in higher SNF in milk. In the nutritional point of view, the present study clearly showed CSS can be used as a roughage for dairy cows in the dry season.

A metabolism trial with four castrated male Brahman cattle, average body weight 320 kg, was conducted in order to determine the nutritive value of chopped sugarcane stalk (CSS) for the establishment of feeding strategy in the dry season in Northeast Thailand. Animals were subjected to the following four dietary treatments: Treatment 1; 100% of CSS, Treatment 2; 70% of CSS and 30% of commercial complete feed (TMR), Treatment 3; 40% of CSS and 60% of TMR, and Treatment 4; 100% of TMR. The average CP, ether extracts, nitrogen free extracts, crude fiber and ash contents of CSS were 2.0, 0.9, 79.0, 16.1 and 2.2%, respectively. Although the amount of feed given was approximately at maintenance level, animals in treatments 1 and 2 refused a part of feed. The metabolism trial revealed that total digestible nutrient and metabolizable energy contents of CSS were 61.5% and 9.04 MJ/kgDM, respectively, when it was properly supplemented with protein sources. Nutritive value of CSS was lowered when animals were given CSS solely. This was due to the large loss of energy into urine and methane. Voluntary intake of CSS in cattle was not enough to satisfy energy requirement for maintenance. The CSS can be used as a roughage for feeding cattle in the dry season with proper supplementation of protein and energy.