The Energy Contents of Broken Rice for Lactating Dairy Cows

The objectives of this research were to determine 1) the energy contents of broken rice in dairy cows by animal calorimetry and 2) the effects of various levels of broken rice in diets on dairy cow performance. Four multiparous Holstein-Friesian crossbred cows at 70 ± 31 (mean ± SD) days in milk were assigned according to a 4 × 4 Latin square design with four periods. The four treatments included a diet substitution with broken rice on a 0, 12, 24, and 36% dry matter basis in the basal ration. Indirect calorimetry with a ventilated head box respiration system was used to determine energy metabolism. The substitution of broken rice in the diet did not affect dry matter intake, milk yield, milk composition, feed efficiency or energy balance (p > 0.05). Increasing broken rice substitution in the diet resulted in a linear increase in enteric methane energy losses and digestibility of dry matter, organic matter, and fiber (p < 0.05), whereas the digestibility of crude protein and ether extract decreased (p < 0.05). The metabolizable energy requirement for maintenance was 504 kJ/kg metabolic body weight, and the efficiency of metabolizable energy used for lactation was 0.76. The estimated net energy value of broken rice for lactation was 8.68 MJ/kg. Our results indicated that increasing the proportion of broken rice in the diet up to 36% had no adverse effect on feed intake and production performance in dairy cows.