Barley crude protein

Hay has been analysed by NIR for crude protein, acid detergent fibre, dry matter, lignin and IVDMD, rapeseed for oil and water and spring field beans for N to name but a few applications. Most macroinorganic constituents of peaty soil can be determined, and moulds have been measured in hay, tall fescue and barley (Malley and Nilsson, 1995). A short bibliography is given below. 

Hull-less barley varieties have been developed, in which the hull separates during threshing. These varieties contain more protein and less fibre than conventional barley, and theoretically should be superior in nutritive value to conventional barley. However, Ravindran et al. (2007) found that the ME (N-corrected basis) was similar in hull-less and hulled barley. The chemical composition of six Brazilian hull-less barley cultivars was studied by Helm and de Francisco (2004) and reported as follows. The highest constituents were starch (575-631 g/kg), crude protein (125-159 g/kg) and total dietary fibre (TDF 124-174g/kg), the starch and crude protein contents being in agreement with those previously reported for Swedish (Elfverson et al., 1999) and Canadian (Li et al., 2001) varieties. The other reported values (g/ kg) were ash content 15.1-22.7, ether extract 29.1M0.0, starch 574.6-631.4, insoluble dietary fibre 80.7-121.6, soluble dietary fibre 43.0-64.5 and p-glucan 37.0-57.7. 

Pig and poultry diets based on cereals and vegetable protein sources are now routinely supplemented with L-lysine hydrochloride (supplying 780 g lysine/kg), dl-methionine and L-threonine. A diet for a finishing pig, which has to contain 10 g lysine/kg, required a combination of 750 g barley and 250 g soya bean meal/kg, and this mix has a crude protein content of 185 g/kg (see Appendix 2, Table A.2.2.2). With the inclusion of 2 g of lysine hydrochloride, the same lysine content can be achieved with a mix of 808 g barley and 190 g soya bean meal, and the protein content is reduced to 165 g/kg. Such reductions in crude protein content have maintained a balanced supply of amino acids and resulted in improved rates of liveweight gain and food conversion efficiency. It is important that the supplementary acids are not used excessively to satisfy the animal s requirements, since this may bring about an undersupply of other essential amino acids. 

Reducing the level of dietary crude protein (CP) is an effective means to reduce nitrogen excretion but requires reliable information about the pigs requirements for potentially limiting amino acids (AA). Isoleucine (lie) may be limiting in low CP pig diets that are supplemented with lysine (Lys), threonine, methionine and tryptophan (Liu et al., 1999). The objective of this study was to estimate the optimum dietary standardized ileal digestible (SID) Ile Lys ratio in 25- to 40-kg pigs that were fed wheat-barley based diets. 

SA in Table II - nmoles/hr/mg protein and N.D - not detectable. Tobacco, soy cultures and barley seedlings were the best source of ALS, both in terms of specific activity and total units. The enzyme preparations from all sources were unstable in buffer solutions in spite of protective thiol agents. The inactivation of ALS in the crude extract of tobacco showed a distinct biphasic kinetics, implying the presence of at least two isozymes (unpublished observations). The presence of two ALS genes in tobacco (29) and at least three in microorganisms (18) has also been noted by other workers. ALS from barley was most amenable to purification. Table III gives a profile for the rapid purification of this enzyme with high recovery. 

Table 1. Activities of HPR and GR (nkat mg protein) in crude leaf extracts of wild-type barley or LaPr 88/29 using either NADH or NADPH as a source of reductant.

Figure 2 Cerulenin binds covalently to the active site cysteine of KAS I condensing enzymes (A). H-cerulenin labelled or tagged proteins are resolved by anion exchange chromatography as illustrated in (B) for E. coli [3] and in (C) for barley [4]. While only three KAS I proteins are tagged in enriched barley chloroplast preparations, variable numbers of proteins in addition to X and B (KAS I) can be tagged in crude E. coli preparations depending on the experimental conditions.

Although most NRs are regulated by nitrate, constitutive NRs have been reported in several species. Soybean contains two constitutive NRs, an NAD(P)H NR and an NADH NR, which are distinct from the typical inducible NADH NR present in soybean and most plant species (Nelson et ai, 1983 Streit and Harper, 1986). Tobacco plants (Muller, 1983) and cells (Marion-Poll et ai, 1984 Muller and Grafe, 1978) have moderate levels of constitutive NR activity. In tobacco the constitutive NR activity is presumed to be the NADH NR since mutants lack both the constitutive and inducible NR activities. In barley a constitutive NR was detected after electrophoresis of wild-type and mutant narla crude extracts. This NR was distinct from the major inducible NR (Heath-Pagliuso et ai, 1984). The relationship of this NR to the NAD(P)H NR in nar a is not known, although our data indicate that the NAD(P)H NR is induced by nitrate (Warner and Huffaker, 1989). Low levels of a constitutive NR have also been observed in maize (Remmler and Campbell, 1986). The significance of low levels of apparent constitutive NR should be considered with caution since NR mRNA in barley (Melzer et ai, 1989) and NR protein in maize (Oaks et al., 1988) appear to be induced by very low levels of nitrate. 

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