Homework Assignment #1
1. (1)Cellulose is a polymer of what type of molecules?
2. (1)Which starch molecule is a branched polymer of glucose? Amylopectin
3. (1)Define the volume of one bushel in cubic feet.
1 bushels = 1.24445602149 cubic feet.
1 cubic meter = 28.3775930707 bushels.
4. (3)What are the conversion factors for crude protein content for cereal grains, if total nitrogen is known?
Factor for Cereal Grains
N x 6.25
This factor is used for all cereals except rice and wheat. 0 Rice protein: N x 5.95
1 Wheat protein: N x 5.7
*A portion of N in some coproducts is found as nonprotein nitrogen (NPN) and, therefore, the value calculated by N x 6.25 is referred to as “crude”, rather than true, protein.
5. (2)Give two limitations of why crude protein is an inaccurate measure (i.e.,“crude”).
Crude fiber levels are guaranteed on feed labels but TDF is a more useful measure of dietary fiber content.
When the crude fiber system was developed, it was thought to represent most of the cell wall portion. However, later it was discovered that it did not account for some of the hemicellulose and lignin components.
6. (5)What do crude fiber, ADF, NDF and TDF actually measure? The method for determining crude fiber consists basically of measuring the residue remaining after acid and basic hydrolysis. It is known that the crude fiber method covers 50%-80%of the cellulose, 10 %- 50% of the lignin, and 20% of the hemicelluloses. http://archive.unu.edu/unupress/food/8F024e/8F024E09.htm
Acid Detergent Fiber (ADF) is a measure of the fibrous part of a plant (cellulose and lignin) that the animal cannot digest. Think of coarse or woody forages (or straw) and so much of the plant is indigestible fiber that http://answers.yahoo.com/question/index?qid=20100920154955AAbfrEP Neutral Detergent Fiber (NDF) measures the fiber content in forages. Total cell wall, which is the ADF fraction plus hemicellulose.
Total dietary fiber (TDF)
Defined as polysaccharides and lignin resistant to mammalian digestive enzymes and thus relevant to most nonruminant animals with hind gut fermentation (Prosky et al 1984).
7. (5)What is the limitation of crude fat measurement, when using the typical standard method?
Crude fat content is estimated by extracting a ground sample with diethyl ether (AOAC, 1984).
Ether soluble components (ether extract) may include true fats and oils, fatty acid esters, compound lipids and fat soluble vitamins or provitamins such as the carotenoids, all of which may have nutritional value.
However, ether extract may also contain significant concentrations of indigestible waxes, resins and essential oils.
Crude fat is a typical expression of oil content in soybean and soybean meal in the soybean processing industry.
Adapted from : www.livestocktrail.uiuc.edu/sand/paperDisplay.cfm?ContentID=9674
8. (10)For each type of grain and oil seed listed, how much does one bushel(bu) weigh(inlbs.)?Report values for grain having US Standard Grade No. 1. Hints: weight per bushel is often called test weight or standard bushel weight and is defined by the USDA. Be sure to give the reference for each value found. For full credit, use credible references such as university or USDA publications. a.) Corn – 56 lb
b.) Sorghum – 56 lb
c.) Barley – 48 lb
d.) Oats – 32 lb
e.) Wheat – 60 lb
f.) Soybeans – 60 lb...