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| In a companion study, 16 Holstein cows were
used in a 4x4 Latin square-designed study to compare the effects of feeding
supplemental protein as urea, solvent soybean meal, cottonseed meal or
canola meal on milk production, nutrient utilization and ruminal metabolism.
The alfalfa silage, corn silage, high-moisture corn diet was formulated
to contain 16.6% crude protein. Feed intake and productivity were reduced
and milk urea, blood urea and ruminal ammonia were increased when cows
were fed the urea containing supplement compared to the diets supplemented
with the oilseed meals. No difference was observed for milk yields among
the soybean, cottonseed and canola meal supplemented diets. Yields of
milk fat and protein were highest for the canola meal diet, followed by
the soybean meal diet and lowest for the cottonseed meal diet. Urinary
excretion of nitrogen was greatest for the urea diet, intermediate for
the soybean and canola meal diets, and lowest for the cottonseed meal
supplement diet. This experiment supports the companion paper that concluded
the importance of supplementing dairy rations with high-quality oilseed
protein ingredients to assure adequate microbial protein and rumen- undegraded
protein needed to meet metabolizable protein requirements for high-producing
dairy cows. Brito, A.F., and G.A. Broderick. 2007. Effect of different protein supplements on milk production and nutrient utilization in lactating dairy cows. J. Dairy Sci. 90: 1816-1827. Four lactating dairy cows with ruminal and duodenal cannulas were used to evaluate the effects of soybean meal processing on ruminal and intestinal digestibility of crude protein and amino acids. Solvent extracted soybean meal was compared to expeller soybean meal, soybean meal treated with lignosulfonate and meal processed with extra heat and containing higher levels of soyhulls. The results indicated that the three treated soybean meals increased rumen-undegrated protein levels by about 25% compared to the solvent soybean meal, however, no significant differences were observed in intestinal disappearance in situ among the different soybean meals. This study showed based on in situ measurements, that heat and chemical treatment of soybean meal enhanced the supply of most essential and nonessential amino acids to the small intestine of high-producing dairy cows. Borucki Castro, S.I. and co-workers. 2007. Ruminal degradation and intestinal digestion of protein and amino acids in treated soybean meal products. J. Dairy Sci. 90: 810-822. Low-phytate Soybeans Researchers are interested in developing soybean lines with higher amounts of digestible phosphorus that will reduce the level of supplemental phosphorus needed to meet the feed’s specifications and will reduce levels of non-digestible phosphorus levels in animal waste. Chinese researchers developed and characterized two mutant soybean lines with low levels of phytate phosphorus. The first mutant line had phytate phosphorus levels reduced by 66.6% and a six-fold increase in inorganic phosphorus levels. The second soybean line had a reduction of 46.3% in phytate phosphorus and a 1.4 fold increase in organic phosphorus compared to the non-mutant progenitor lines. Since the total phosphorus levels were similar to their parent, the reduced phytate phosphorus and increased organic phosphorus would result in increased available phosphorus levels. The low phytate mutations were shown to be both inherited in a single recessive gene. Gene sequence data and progeny analyses indicated the two lines were genetically different. Differences between the two lines were also observed in field emergence studies; field emergence and yield traits in line with the 46.3% reduction in phytate phosphorus were similar to the progenitor line. (Note-The significance of this research is the research advances our understanding of the genetics, biochemical and molecular control of phytate phosphorus synthesis in the soybean. Continued study may result in developing agronomically productive soybean lines with low-phytate traits that have both nutritional and environmental advantages to the livestock producer). Yuan, F.J. and co-workers. 2007. Generation and characterization of two novel low phytate mutations in soybean (Glycine max L. Merr). Theoretical Applied Genetics, August 16. |
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