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RUMEN ESCAPE PROTEIN FOR LACTATING COWS AND UREA-AMMONIATION OF WHEAT STRAW
Abstract
The relative value of a mixture of corn gluten meal (CGM) and blood meal (BM) compared to soybean meal (SBM) was determined. The mixture was formulated in a 50:50 ratio of crude protein (dry matter basis) from each source. In a trial with dairy cows in mid-lactation, daily milk yields of cows receiving low levels of the mixture (LM) were similar (P $>$.10) to those obtained with high levels of the mixture (HM) or SBM. Furthermore, 3.5% fat-corrected milk yields of cows fed the urea supplemented control (C) diet did not differ (P $>$.10) from those of cows fed the natural supplemental diets. Plasma amino acid levels were closely related to the levels of amino acids in the mixture in the diet. Plasma amino acid levels for cows fed the C and SBM diets were very similar. Two trials were conducted with beef cows in early- and mid-lactation. Average daily gains of cows in mid lactation were lower (P $<$.06) when fed the control (C) diet than when cows were fed SBM or CGM-BM. Cows in early lactation receiving SBM, or low and high levels of the mixture gained faster (P $<$.025) than cows fed C. In both trials, average daily gain of calves did not differ among dietary treatments. Ammoniation of wheat straw using urea produced a positive and linear decrease (P $<$.05) in cell wall fractions as level as urea-nitrogen increased in the treatment from 1.5 to 4.5%. In vitro dry matter disappearance (IVDMD) and cell wall fractions were affected (P $<$.05) by the interaction among urea level, moisture level and treatment time. Higher levels of urea were associated with higher IVDMD values (P $<$.05). As moisture content increased, higher IVDMD values were also obtained (P $<$ 0.05). Longer treatment periods were required to obtain similar results with low urea and moisture levels when compared to high urea and moisture levels. Nitrogen content of the ammoniated straw increased (P $<$.05) as urea-nitrogen level increased. However, less nitrogen was retained (P $<$.05) as the moisture level and treatment time increased. Part of the added nitrogen was retained in the fibrous fraction (Acid detergent insoluble nitrogen). The level of nitrogen bound to the fiber increased (P $<$.05) with urea level and time, but decreased (P $<$.05) with higher moisture content.
Subject Area
Livestock
Recommended Citation
DE GRACIA GALVEZ, MANUEL SALVADOR, "RUMEN ESCAPE PROTEIN FOR LACTATING COWS AND UREA-AMMONIATION OF WHEAT STRAW" (1987). ETD collection for University of Nebraska-Lincoln. AAI8719775.
https://digitalcommons.unl.edu/dissertations/AAI8719775