Nutritive value of forages

Isawa, K., Abe, A., Nishihara, N. Influence of diseases on the chemical composition and nutritive value of forage crops. I. Chemical composition of Italian ryegrass infected with crown rust. Ann Phytopathol Soc Japan 1974 40 86-92. 

Table 18.2 Typical yields and nutritional values of forage crops compared with grass...

To some extent, the failure to replace loss of sulfate from the soil is compensated in areas subject to atmospheric pollution. Vast quantities of sulfur dioxide gas are discharged into the atmosphere every year all over the western world, and it has long been recognised that the presence of this gas in the atmosphere is a public health hazard and that it is markedly injurious to vegetation [115-117]. The damage to leaves exposed to sulfur dioxide does not, however, appear to be associated with any deleterious effect on the nutritive value of forage crops [118]. 

BARRY T N, MCNABB w c (1999) The implications of condensed tannins on the nutritive value of temperate forages fed to ruminants. Br J Nutr. 81 263-72. 

The rapes grown in Britain are usually swede-rapes (B. napus), although turnip-rapes (B. campestris) also occur. Rape may be included in seed mixtures for pastures, in order to provide forage until the grasses become established. The nutritive value of rapes is similar to that of the kales. A forage rape and kale hybrid (var. Swift) is valued for fast growth combined with winter hardiness. 

Near-infrared reflectance spectroscopy has been traditionally developed in animal science to evaluate the chemical composition of forages (4, 5, 15). Compared with forages, little information is available on the suitability of NIR spectroscopy in the estimation of the chemical composition and nutritive value of by-product materials derived from livestock. The information available in the literature relates only to the use of NIR spectroscopy to determine gross chemical composition such as dry matter (DM), crude protein (CP), fat (oil), and amino acid content in a few livestock animal by-products. Examples of NIR applications in animal by-products are summarized in Tables 8.3.3 and 8.3.4. Good correlations were found for DM and CP in the different animal by-products. Although good correlations were found for some amino acids, Fontaine et al. (22) stated that the calibration for sulfur-containing amino acids are... 

In conclusion, neither of the common fiber measures used to evaluate the nutritional value of feedstuffs, such as NDF and ADF, nor the more advanced DF measure, was able to predict the variation in dE and DE in preserved forage for horses with an acceptable accuracy as reflected in the low values. 

Other Factors. Forage plants contain tannins (9, 51) and other substances which affect nutritive value. These are not ordinarily thought of in schemes for forage evaluation. 

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