WHEAT: COMPOSITION AND FEEDING VALUE FOR POULTRY - Soybean and Wheat Crops: Growth, Fertilization, and Yield - page 247

Variation in the Nutrient Composition of Wheat

The nutrient composition of wheat of a given type and variety varies from year to year
depending upon area, growing location, fertilization rate, moisture conditions and other
agronomic factors. A summary of variation reported in the literature on the chemical
composition of wheat is given in Table 3. Of all cereal grains, wheat is the most variable in
protein content. The crude protein content (N x 5.83) of wheat may vary from 8 to 18%, but
more typically between 10 and 15 depending on the type of wheat, climate and soil fertility.

Table 2. Amino acid composition of wheat as influenced by grain protein level 1,2

Protein level in wheat, % Corn

(8% protein)

9 12 16

Indispensable amino acids

Arginine 0.47 0.57 0.75 0.39

Histidine 0.26 0.32 0.42 0.24

Isoleucine 0.37 0.46 0.64 0.33

Leucine 0.68 0.85 1.13 1.09

Lysine 0.31 0.36 0.47 0.25

Methionine 0.13 0.16 0.20 0.14

Phenylalanine 0.45 0.60 0.80 0.43

Threonine 0.32 0.38 0.52 0.37

Valine 0.45 0.55 0.72 0.44

Dispensable amino acids

Alanine 0.38 0.46 0.56 0.67

Aspartic acid 0.53 0.61 0.85 0.57

Glycine 0.43 0.52 0.71 0.35

Glutamic acid 2.84 4.01 5.45 1.62

Serine 0.55 0.68 0.83 0.46

Tyrosine 0.24 0.33 0.48 0.44

1 Nitrogen x 5.83.
2 Ravindran et al . (1998; 2005).

Svihus and Gullord (2002) compared 16 samples of Norwegian wheats, reported
variation in starch content between 61.4 and 71.2%, protein between 10.9 and 15.4%, fat
between 2.2 and 3.4% and crude fiber between 2.0 and 2.6%. Choct et al. (1999) surveyed
Australian wheat over 3 years reported large variation in AME value, starch, protein, and
soluble and insoluble NSP due to year of harvest and geographical location. Carré et al.
(2007) stated that the wheat protein content depend more on agronomic and climatic
conditions, rather than on cultivars. Wiseman and McNab (1995) concluded that wheat
cultivar had greater impact on AME than either production site or harvest year. In contrast,
Choct (1995) showed that seasonal effects had greater influence than variety on AME and
NSP contents. Wheats with high soluble-NSP contents was related to rainfall and
environmental temperature patterns during the period of grain maturation. Furthermore, starch
content and granular structure, composition, and distribution in the developing grain can also
be influenced by the climatic conditions (Hughes and Choct, 1999).