Effects of dietary n-3 polyunsaturated fatty acids and ... - FINS

1 st WorkshopXIII International Feed Technology SymposiumThe content of butyric acid could be reduced by wilting the cut mass of sudan grassto 35% dry matter content, which would improve competitiveness of lactic acidbacteria and increase production of lactic at the expense of butyric acid. This wouldconsiderably improve consumption by cattle.Having in mind indicators of silage quality presented in Table 2, it would beimportant to review realized yields per hectare for individual fractions with variousdigestibility for both cultures. The light digestible fraction would contain rawprotein, raw fat, and nonstructural carbohydrate. The middle digestible fractionwould contain hemicellulose, while the hardly digestible fraction would include ADFfibers.Table 3. Yield of individual fractions with different digestibilityFraction / SpeciesLight digestiblefractionMiddle digestiblefractionHardly digestiblefractionYield of maize silage32,4 t/haYield ofCumulative,fraction,t/hat/haYield of sudan grass silage66,7 t/haYield offraction, t/haCumulative,t/ha6,77 6,77 4,64 4,642,13 8,9 5,64 10,282,59 11,49 8,71 18,99A careful analysis of results in Table 3, shows that for maize there is a higher yieldonly for the light digestible fraction, which is by all means the most important, andthat this yield is almost 50% higher than for sudan grass. However, the cumulativeyield of the light and the middle digestible fraction, that can still be fairly wellutilized by cattle, was considerably higher for sudan grass than for maize. Thisdifference in yield is especially in favor of sudan grass if the calculation includes allthree fractions. Although the hardly digestible fraction is a hardly accessible sourceof energy and body building substances, still a considerable part of this fraction(cellulose) is also utilized by cattle, owing to the presence of symbiotic cellulyticbacteria in their pregasters (1).When analyzing results from Table 3, one should keep in mind that these resultspertain to 2004, which had high above average precipitation. There is cause topresume that the relative yield increase of light and middle digestible fractions ofsudan grass compared to maize was even more pronounced in unfavorable years suchas 2003 (draught).Owing to its ability to regenerate, sudan grass can be used freshly cut as greenfodder, and in such use it offers three cuts a year without any problem (5). Used thus(at earlier phases of development) its digestibility is much higher, and cattle readilyconsumes it in large quantities in this form, therefore it often happens that duringperiods of feeding freshly cut sudan grass, the average milk yield on the farm growsby as much as two liters per animal, with a certain decrease of dry matter in milk.257