| | Abstract | Introduction | Materials and methods | Results and discussion | Conclusion | References
Abstract
Both malt and feed barley markets prefer high test weight grain, but for the malt industry other traits must also be met such as low protein, high malt extract, high alpha-amylase, high diastatic power (DP) and low beta-glucans. This study was conducted to determine the relationship of traits desirable in malting barley to those for feed. Quality analyses using NIRS were conducted on twenty barley lines and cultivars from our advanced two-row yield trials grown under eight environmental regimes in 2003. Digestible energy content and protein digestibility were found to be positively correlated with protein, DP, malt beta-glucan and negatively correlated with malt extract and alpha-amylase. Starch content and total fiber were negatively correlated with protein and DP. Starch was positively correlated to malt extract and alpha-amylase and negatively correlated to malt beta-glucan. When we select for good malting quality, we may be selecting away from high digestible energy content. However on a line by line basis, many lines had traits that would be desirable for both feed and malt markets. There are also lines that have very high digestible energy contents that would make them superior feeds.
Introduction
Both malt and feed barley markets prefer high test weight grain, but for the malt industry other traits must also be met such as low protein, high malt extract, high alpha-amylase, high diastatic power (DP) and low beta-glucans.
Quality factors for feed are less well defined. Feed quality is often defined as animal performance, that is related to intake and nutrient digestibility (Coleman and Moore 2003). For the monogastric animal, digestible energy and protein digestibility are two quality factors of importance. For the ruminant animal, protein, starch and fibre contents are quality factors of importance.
The purpose of this study was to determine the relationship of malting quality traits to feed quality traits in a diverse population of two-rowed barley.
Materials and Methods
Sites: Calmar, Lacombe (high fertility, low fertility, late seeding), Olds, Stettler (regular and late seeding), and Trochu.
Material: 20 lines/cultivars including check cultivars AC Metcalfe (malting), CDC Dolly (feed), Harrington (malting) and Seebe (feed)
Methodology: NIRS determination of malting and feed quality traits (Helm et al. 1997; Helm 1998).
Statistical analyses: Pearson correlation coefficients determined using SASRTM
Results and Discussion
Table 1. Correlations of feed to malting quality traits
* = Significant at P<0.05
** = Significant at P<0.01
*** = Significant at P<0.001
NS= Non-significant
Correlations of feed to malting quality traits
Digestible energy content was negatively correlated with extract and alpha-amylase, so selection for high levels of these traits for malting would tend to result in low digestible energy contents; as well it was positively correlated with protein and beta-glucan so selection for low protein (10-12%) and beta-glucan for malting would tend to also result in low digestible energy content.
Protein digestibility was also negatively correlated with extract and alpha amylase and positively correlated with protein and beta-glucan so selection towards favourable malting quality would tend to result in lower protein digestibility.
Therefore, selection of traits that would be good for malting would tend to result in reduced feed value for hogs.
Starch content was positively correlated with extract and alpha-amylase, so selection for high levels of these traits should increase starch content as well; and it was negatively correlated with protein, diastatic power, and beta-glucan, so while selection for low levels of protein and beta-blucan should result in higher starch levels, selection for high diastatic power would result in lower starch levels.
Total fiber content was not significantly correlated with extract or alpha amylase. Total fiber content was negative correlated with protein and diastatic power and positively correlated with beta-glucan, so selection for low protein would result in higher fiber levels while selection for high diastatic power and low beta-glucan would result in low total fiber content.
Therefore, selection of traits that would be good for malting would tend to have a positive or no effect on feed value for ruminants.
Genotypic differences in malting and feed quality traits
While the feed type Seebe had the highest protein content of all the genotypes tested (Fig. 1), there was no clear-cut relationship between protein and malting or feed quality in the other genotypes; perhaps because all malting types require protein to supply enzymes necessary for modification during malting; and no premium is given to feed types with high protein content. Most of the breeding lines were intermediate for protein content.
Seebe, the feed type, had the lowest extract levels and AC Metcalfe and Harrington, the malting types, had high extract levels (Fig. 2). While most of the breeding lines tended to have intermediate levels, some were higher than the malting checks.
For diastatic power (Fig. 3) and alpha-amylase (Fig. 4), most of the breeding lines were intermediate to the low for Seebe (feed) and the highs for Harrington and AC Metcalfe (malting).
For beta-glucan (Fig. 5), most of the breeding lines were intermediate to the high for Seebe (feed) and the low for AC Metcalfe (malting).
Two of the breeding lines had higher digestible energy levels than the highest level for the feed variety CDC Dolly (Fig. 6). Seebe, Harrington and AC Metcalfe had similar intermediate digestible energy levels.
Harrington (malting) had the best protein digestibility (Fig. 7) of the genotypes tested and there was great variability in this trait among the lines tested.
There was great variability in starch content (Fig. 8) among the lines tested and while AC Metcalfe (malting) had a high starch content, starch contents for CDC Dolly and Seebe (feed) were similar to that for Harrington (malting).
There was great variability in total fiber content among the lines tested (Fig. 9), with Seebe and Harrington having relatively higher levels than AC Metcalfe and CDC Dolly. Some of the lines had very high total fiber levels while others were much lower than the checks.
The breeding line H97006005 had low total fiber and high digestible energy with intermediate starch, protein and protein digestibility; perhaps this line could be a rapidly degradable, high energy feed for monogastrics.
The breeding line H93103004 had high malt extract, adequate alpha amylase and DP, and low beta-glucan; this line may make it as a malting type with good protein, protein digestibility and starch, and intermediate total fiber for feed (although digestible energy for this line was low and protein content was high).
Conclusion
Genotypic variability exists in barley to select for good feed and malting traits; however, good malting lines may not make the best feeds for all classes of livestock.
If protein is kept in a range of (12-14%), then selection pressure towards malting quality should not lead to poor feed traits and it should be possible in the breeding program to keep lines with potential for either malting or feed.
There are genotypes that may have superior feed traits for monogastric and ruminant animals; selection for these traits would be possible; however there is little incentive in the current registration and marketing system to prompt for this selection procedure.
References
Cohen, S.W. and Moore, J.E. 2003. Feed quality and animal performance. Field Crops Research. 84:17-29.
Helm, J.H., Oatway, L.A. and Jedel, P.E. 1997. The use of NIR to screen early generations for quality in barley. CSSA Ann. Meeting, Anaheim, CA, Oct 26-30.
Helm, J.H. 1998. Potential agricultural applications of NIR. Feed Grain Quality Conference, Edmonton, AB, Nov 8-10.
Pat Juskiw, Jim Helm and Lori Oatway
Presented at the Canadian Society of Agronomy Meetings, The Science of Changing Climates Conference, University of Alberta, Edmonton, July 20-23, 2004.
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