Effect of replacing corn with brown rice grain in a total mixed ration silage on milk production, ruminal fermentation and nitrogen balance in lactating dairy cows

Abstract

Nine multiparous Holstein cows were used in a replicated 3 × 3 Latin square design to determine the effects of substituting corn grain with brown rice (BR) grain in total mixed ration (TMR) silage on milk yield, ruminal fermentation and nitrogen (N) balance. The TMR silages were made from the ensiling of TMR containing (dry matter basis) 50.1% forage in rice silage and corn silage combination, and 49.9% concentrate. The grain portion of the diets contained 31.2% steam-flaked corn, 31.2% steam-flaked BR or an equal mixture of corn and BR. Dietary treatments did not affect dry matter intake, milk yield and milk fat, protein and lactose yields. The ruminal pH and total volatile fatty acid concentrations were not affected by dietary treatment. The urinary N excretion decreased linearly (P < 0.01) in response to increased levels of BR, with no dietary effect on N intake, N secretion in milk and fecal N excretion. Our results indicate that steam-flaked BR is a suitable replacement for steam-flaked corn in dairy cow diets, and that it can be included in rations to a level of at least 31.2% of dry matter without adverse effects on milk production, when cows were fed rice silage and corn silage-based diets.

Milk production, nutrient digestibility and nitrogen balance in lactating cows fed total mixed ration silages containing steam‐flaked brown rice as substitute for steam‐flaked corn, and wet food by‐products

“…However, significant differences in the DM, EE, NDF, ADF and starch contents of TMR silages were observed (P = 0.029, P = 0.020, P = 0.003, P = 0.036 and P = 0.003, respectively). This result is in agreement with that of Miyaji et al (2012), who prepared TMR silages containing 31.2% steam-flaked BR, 31.2% steam-flaked corn or a 50:50 mixture of BR and corn on a DM basis. These differences of chemical composition are a reflection of differences in these contents of the original grains (Miyaji et al 2010.…”

“…The starch content of BR is slightly greater than that of corn grain, and the BR starch is digested more rapidly than the corn grain starch (Enishi et al 2000;Miyaji et al 2010Miyaji et al , 2012. Corn grain is used as the main dietary starch source in dairy cow diets in Japan.…”

“…Corn grain is used as the main dietary starch source in dairy cow diets in Japan. Meanwhile, Miyaji et al (2012) reported that the replacement of corn with BR had little impact on DMI, milk yield and composition and ruminal pH, and improved the dietary N utilization. The starch content of BR is slightly greater than that of corn grain, and the BR starch is digested more rapidly than the corn grain starch (Enishi et al 2000;Miyaji et al 2010Miyaji et al , 2012.…”

Effects of ruminally degradable starch levels on performance, nitrogen balance, and nutrient digestibility in dairy cows fed low corn-based starch diets

“…This result was due to the DMI being similar between the dietary treatments and that the diets were isonitrogenous. However, the urinary N excretion and urinary N excretion as a proportion of N intake were less in cows fed high RDS TMR than in cows fed low RDS TMR, and the result was in agreement with the previous studies [22,34]. Ohtani et al [35] showed that supplying more fermentable starch in the diet could increase production of ruminal propionic acid which is a glucose precursor, and then reduce urinary N losses through reducing the amino acids (AA) used for gluconeogenesis.…”

“…N retention as a proportion of N was similar between the dietary treatments. This agrees with a previous report [16] and contrasts with other previous reports [20,34]. The inconsistent effects of RDS levels on N retention as a proportion of N can be attributed to the differences of N intake and starch levels.…”