Abstract
Balance trials using lactating Holstein cows in early lactation were conducted to compare the feeding value of "Hoshiaoba" which is a new breed of rice for whole crop silage with that of timothy hay. Three cows were fed the diet consisting of 35% (on a dry matter basis) timothy hay and 65% concentrates (Timothy treatment) and two cows were fed the diet consisting of 35% "Hoshiaoba" and 65% concentrates (Hoshiaoba treatment) during the trials. The ingredient composition of the concentrates in the two treatments was the same. In "Hoshiaoba" silage and timothy hay, the content of crude protein, nitrogen cell wall free extracts, and organic cell wall (OCW) were 6.7 and 8.2%, 23.2 and 17.3%, and 55.0 and 67.3%, respectively. Dry matter intake of "Hoshiaoba" silage (46.5g/kg metabolic body size/day) tended (P<0.10) to be lower than that of timothy hay (60.4g/kg metabolic body size/day). The digestibility of OCW in Hoshiaoba treatment was lower (P<0.05) than that in Timothy treatment. As a proportion of gross energy, urinary energy tended (P<0.10) to be lower, and methane energy or heat production were statistically higher (P<0.05 or P<0.10) in Hoshiaoba treatment than those in Timothy treatment. Fat corrected milk (4%) yield was not significantly different between Timothy treatment (32.5kg/head/day) and Hoshiaoba treatment (31.4kg/head/day). Although "Hoshiaoba" silage contained lower amount of organic cell wall, roughage value index in "Hoshiaoba" treatment was similar to Timothy treatment. The average excretion rate of ear and unhulled rice of "Hoshiaoba" silage into feces were 30.2 and 22.7%, respectively. These results suggested that dry matter intake and OCW digestibility of "Hoshiaoba" silage was decreased compared with timothy hay, and "Hoshiaoba" silage exhibited 30.2% in excretion rate of ear, because of their hard texture. In order to improve the feeding value of "Hoshiaoba" silage in Holstein cows, it is necessary to improve dry matter intake as well as digestibility of ear of "Hoshiaoba" silage.
