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

Westreicher-Kristen, Edwin; Südekum, Karl‐Heinz

doi:10.1016/j.anifeedsci.2018.09.018

Cited by 2 publications

(1 citation statement)

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“…Even though these results should be interpreted with care, and that equations are not recommended to be directly used to estimate MCP synthesis based on OBCFA, they give an indication about the effect of including RCS in the diets of dairy cows. Finally, the effect of replacing MS with RCS on the estimated MCP synthesis of this study matches with the reduction in concentration and yield of milk protein [16], the estimated flow of utilizable CP at the duodenum, based on an in vitro technique [25] or that calculated with an official equation of the German protein evaluation system [39], and the concentration of purine bases and total N in liquid-associated microbes in vitro [28]. The latter indicates the relative reliability of the approaches used to estimate MCP synthesis.…”

Section: Limitations Of the Present Studysupporting

confidence: 64%

Relationship of Milk Odd- and Branched-Chain Fatty Acids with Urine Parameters and Ruminal Microbial Protein Synthesis in Dairy Cows Fed Different Proportions of Maize Silage and Red Clover Silage

Westreicher-Kristen

Castro-Montoya

Hasler

et al. 2020

Animals

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The aim of this study was to evaluate the relationship of milk odd- and branched-chain fatty acids (OBCFA) with urinary purine derivates and estimated ruminal microbial crude protein (MCP) synthesis. Forty-four lactating Holstein cows were used in a 4 × 4 Latin square design with 21-day periods comprised of a 13-day adaptation phase to diet followed by an 8-day sampling phase. Differences in estimated MCP yield and milk OBCFA composition were found by feeding total mixed rations containing forage (maize silage, MS; red clover silage, RCS) and concentrates (0.75:0.25) with targeted proportions of RCS to MS of 0.15:0.60, 0.30:0.45, 0.45:0.30, and 0.60:0.15 on a dry matter basis. The MCP was estimated from the total urinary purine derivate (PD) excretion (MCPPD) and intakes of metabolizable energy (MCPME) or digestible organic matter (MCPdOM). The Pearson correlations of individual OBCFA with urinary parameters (uric acid, allantoin, PD and nitrogen) were generally weak (r = −0.37 to 0.55). Yields of individual OBCFA correlated positively with MCPME and MCPdOM (r = 0.21 to 0.55). The prediction of urinary PD concentration was moderate (R2 = 0.64) when including the proportion of iso-C17:0. The prediction of total PD excretion was low (R2 = 0.21) with yields of iso-C15:0, anteiso-C17:0, and iso-C16:0. The prediction of MCPPD was high (R2 = 0.99) when including the iso-C16:0 and cis-9 C17:1 concentrations, while those of MCPME and MCPdOM were low (R2 = 0.37 and 0.36, respectively) when including yields of iso-C15:0, cis-9 C17:1, and iso-C18:0. The correlations and regression analyses demonstrate that the estimated MCP synthesis and urinary PD excretion can be only moderately predicted by yields and concentrations of individual or total OBCFA in cow’s milk. However, milk OBCFA can still be seen as a promising, non-invasive method for predicting rumen function and microbial protein supply in dairy cows because MCP flow was not directly measured in this study but instead indirectly estimated probably comprising considerable deviations of the assumed values from the true ones.

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