The Energy Contents of Broken Rice for Lactating Dairy Cows

SIMPLE SUMMARY: The net energy for lactation of feedstuffs is critical data for a precision dairy feeding system aimed at improving animal productivity and sustainability. The energy value of feedstuffs is required to determine the energy requirements. Broken rice is a byproduct of rice (Oryza sativa) processing that can be used as an energy feed for livestock. In research on broken rice for lactating dairy cows in the tropics, data on energy utilization still needs to be included. Evaluation of the net energy content of broken rice will allow for more precise feeding for lactating dairy cows. Therefore, we aimed to determine the net energy content of broken rice for lactation using animal calorimetry. The findings indicate that increasing the amount of broken rice in cows’ diets could improve dry matter, organic matter, and fiber digestibility but not adversely affect intake, energy balance, or production performance. The net energy for lactation of broken rice in dairy cows was estimated at 8.68 MJ/kg. ABSTRACT: This study aimed to evaluate (1) the net energy for lactation of broken rice in dairy cows and (2) the effects of broken rice substituting in diets on feed intake, nutrient energy utilization, and milk production. An energy metabolism experiment was conducted using a respiration chamber system in four multiparous Holstein crossbred cows (88.6% Holstein × 11.4% Native Thai; body weight of 438 ± 16.0 kg; 70 ± 31 days in milk) according to a 4 × 4 Latin square design with four 21-d periods. The four dietary treatments included a basal diet substitution with broken rice at 0%, 12%, 24%, and 36%. Increasing the substitution rate of broken rice in the diet resulted in unaffected feed intake, milk yield and composition, and energy balance (p > 0.05); however, a linear increase in the digestibility of dry matter, organic matter, and neutral detergent fiber (p < 0.05). The estimated net energy for lactation of broken rice was 8.68 MJ/kg. The net energy requirement for maintenance was estimated at 504 kJ/kg of metabolic body weight. Our results indicated that broken rice is a good energy-feed resource and that increasing the proportion in the diet up to 36% had no adverse effect on dairy cows’ production performance.