Replacing maize silage plus soybean meal with red clover silage plus wheat grain in diets of dairy cows: Modelling the utilizable crude protein at the duodenum, a precursor to metabolizable protein

• Published in: Animal feed science and technology 2018-12, Vol.246, p.29-35
• Main Authors: Westreicher-Kristen, E., Südekum, K.-H.
• Format: Article
• Language: English
• Subjects: Forage legume; Microbial crude protein; Rumen; Ruminally undegraded feed crude protein
• ISSN: 0377-8401; 1873-2216
• DOI: 10.1016/j.anifeedsci.2018.09.018

•The utilizable crude protein (uCP) content of total mixed rations (TMR) was studied.•Maize silage was replaced with red clover silage (RCS) in TMR.•The uCP content in vitro was compared with a “standard German procedure”.•The uCP content of TMR linearly reduced with increasing level of RCS in TMR.•The in vitro uCP values correlated with those from the “standard procedure”. The aim was to evaluate the effect of replacing maize silage (MS) plus soybean meal with red clover silage (RCS) plus wheat grain in total mixed rations (TMR) on utilizable crude protein at the duodenum (uCP), and to evaluate the modified Hohenheim gas test (moHGT) for estimation of uCP supply in dairy cows. The TMR comprised forage and concentrates (0.75:0.25), and the forage portion comprised of MS and RCS. The RCS accounted for 0.15, 0.30, 0.45, or 0.60 of the TMR dry matter. The uCP of the TMR was calculated using the “standard German procedure” as the reference value (uCPGfE) as the sum of ruminally undegraded feed crude protein (RUPGfE) and ruminally synthesized microbial crude protein (MCPGfE). For this, the RUPGfE content was calculated from RUP content based on in situ ruminal degradation of crude protein, and the MCPGfE was calculated based on the contents of crude protein, RUP and metabolizable energy. The moHGT was used to determine the in vitro uCP (uCPmoHGT) and was compared with uCPGfE. The RUPGfE, MCPGfE, uCPGfE and uCPmoHGT were estimated assuming passage rates out of the rumen of 2, 5 and 8%/h. At all assumed passage rates, replacing MS with RCS linearly decreased (P