Influence f Endsperm Type On the Nutritive Value Of Grain Srghum and Crn c. A. Hibberd, R. Schemm and D. G. Wagner Stry in Brief The nutritive value f several varieties f grain srghum and crn was studied utilizing in vitr dry matter disappearance and in vitr gas prductin prcedures. IVDMD studies indicate that crn is the mst digestible, whitebird resistant the least digestible and white-nrmal, heter-yellw and waxy endsperm types intermediate in value. Mrever, heter-yellw and waxy types appear superir t white-nrmal srghum. Gas prductin studies indicate that white-bird resistant srghum exhibits the lwest degree fstarch availability. These studies demnstrate that there is a significant difference in digestibility f varius grain varieties when dry, finely grund. Envirnmental cnditins during the grwing seasn may influence the nutritive value f srghum, althugh this is nt very clear. Intrductin Imprved utilizatin f grain srghum as an energy surce fr ruminants has been f cncern t beef prducers fr sme time. Due t the prevailing water shrtage and fuel csts in western prtins f the Midwest and in the Suthwest, grain prducers are likely t be increasing srghum prductin as a viable alternative t crn. This means mre srghum will likely be available fr feeding. Past research has generally shwn that grain srghum has a lwer feeding value than crn. Several prcessing methds have been shwn t enhance the digestibility f grain srghum. Mrever, sme research has shwn that there is a difference in feeding value between varius varieties f grain srghum. Such studies indicate that it wuld be feasible t initiate srghum breeding prgrams t imprve the nutritive value f grain srghum. Imprved prcessing methds and genetic selectin shuld permit mre efficient utilizatin f srghum. The purpse f this research was t investigate certain nutritive characteristics f several varieties f grain srghum differing in endsperm type and crn. Materials and Methds Several grain srghum varieties differing in endsperm type were grwn at the Perkins Agrnmy Research Statin, and several varieties f crn were 1978 Animal Science Research Reprt 77
grwn at the Panhandle Agrnmy Research Statin. All srghum varieites were planted, grwn and harvested under similar dryland cnditins in tw cnsecutive years. All crn varieties were planted, grwn and harvested under similar irrigated cnditins in the same tw cnsecutive years. Varieties grwn and the endsperm classificatin are illustrated in Tables 1 (Year I) and 2 (Year II). The grains were all finely grund thrugh a 2 mesh screen prir t evaluatin. The chemical cmpsitin f the grains was determined using cnventinal prcedures. In vitr dry matter disappearance (IVDMD) f the grains was determined utilizing strained rumen fluid inculum. Percent dry matter disappearance was determined after 24 hr f incubatin. In vitr gas prductin was als utilized t determine the starch availability f the varius grains. This methd invlves yeast fermentatin f sugars released by enzyme attack n the starch. The grund sample, an enzyme slutin (amylglucsidase) and cmmercial baker's yeast were placed in Ehrlenmeyer flasks, cnnected t an inverted buret gas recvery system. The gas prduced by the yeast during fermentatin was measured as milliliters f gas per gram f dry sample. The mre gas prduced, the greater is the digestibility. Results and Discussin The chemical cmpsitin f the grains is illustrated in Tables 3 (Year I) and 4 (Year II). All f the srghums were much higher in prtein cntent than crn. Significant differences were btained in bth years. In general, the differences were small amng the varius srghum endsperm types, but differences f 1. percent CP r mre did exist. Figure 1 illustrates the IVDMD trends fr the Year I crp. Crn had a significantly higher IVDMD (P<.5) than the srghums. Dry, finely grund white-bird resistant srghum was much mre prly digested (P<.5), and the waxy, white-nrmal and heter-yellw endsperm types were intermediate in value. The data als illustrate that waxy srghum tends t be the mst digestible, althugh the difference was nt significant at the.5 level. IVDMD values fr the secnd crp are illustrated in Figure 2. Similar trends as nted in Year I were bserved. Crn was significantly mre digestible (P<.5) than all the srghum endsperm types. Amng the srghums, white-bird resistant was again significantly lwer (P<.5) than all the thers, and white-nrmal, heter-yellw and waxy were intermediate in value. The white-nrmal endsperm was significantly lwer (P<.5) than heter-yellw and waxy types, indicating that this endsperm type is less desirable than either the heter-yellw r waxy type. In general, in vitr gas prductin studies als shwed the white bird resistant endsperm type t have the lwer starch availability in bth years. The high tannin cntent f the bird resistant varieties f grain srghum may hinder starch digestibility. 78 Oklahma AgriculturalExperimentStatin
Table 1. Descriptive characteristics and classificatin f the grains (Year I) Seed Endsperm cat Waxyr Variety clr Clr Hardness nrmal Classificatin Pineer crn 3149 Clrless Yellw-crn Yellw dent Nrmal crn Crn Pineer crn 336 Clrless Yellw-crn Yellw dent Nrmal crn Darset (bird resistant) Brwn White Intermediate Nrmal White-BR Sft end Brwn White Sft Redlan nrmal Red White Intermediate NrmaD Nrmal White-nrmal OK 612 Red Heter-yellw Intermediate Nrmal Heter-yellw Dwarf redlan Red White Intermediate Waxy Waxy < -...J (» Table 2. Descriptive characteristics and classificatin f the grains (Year 2)» Seed Endsperm :J cat Waxyr 3 Variety clr Clr Hardness nrmal Classificatin Pineer crn Clrless Yellw crn Yellw dent Nrmal C/) crn Crn (D :J Nrthrup king crn Clrless Yellw crn Yellw dent Nrmal crn JJ Darset (bird resistant) Brwn White Intermediate Nrmal White-BR en Sft end Brwn White Sft Nrm II) White-nrmal... Redlan Nrmal Red White Intermediate Nrmal OK 612 Red Heter-yellw Intermediate Nrmal Heter-yellw JJ Dwarf red Ian Red White Intermediate W "C 73BCT 1126 White Yellw Intermediate Waxy -...J < 73BCT 1133-2 Brwn Yellw Intermediate Waxy 733CT 1122-2 Red Yellw Intermediate Wax Waxy
Table 3. Whle grain cmpsitin8 (Year I) Percentage Endspermtype Prtein Etherextract Ash Crn 9.568 5.36 1.7 White-SR 12.8b 3.28 1.36 Waxy 13.12b 1.27 1.9 Heter-yellw 12.9b 2. 1.19 White-nrmal 14.26b 1.3 2.14 8Dry matter basis Table 4. Whle grain cmpsitin8 (Year II) Percentage Endspermtype PrteIn EtherExtract Ash Crn 9.4a 6.72 1.73 White-SR 12.2b.c 4.24 2.18 Waxy 13.54b 5.8 2.78 Heter-yellw 11.61 c 4.4 1.98 White-nrmal 11.48a.b,c 5.48 2.25 adry matter basis 6I 55i... I ~ 5) ~45 '" Q) > c; ~ ~4 ' :::io J I.. 3) 25i 1;1 i :-'=: 'TIT,,;8, &,m, :1 : :Q): :-: ::c: :!'''! :: :4>:,>i : I: :: :: :'>,i : Q): : )1(: : 1:: Q; ::.,::t:,,, 29.2 49.7b 49.8b 52.4b 58.3c Figure 1. Twenty-fur hr In Vitr Dry Matter Digestibility f Dry, Finely Grund Grains (Year Icrp). Significance levels are expressed at.5 levels. 8 Oklahma Agricultural Experiment Statin II """
6 ~ 55 :c ~ '" 5 c> i5... => :I: V 4 N 35 55.cf Figure 2. Twenty-fur hrin Vitr Dry Matter Digestibility f Dry, Finely Grund Grains (Year 2 Crp). Significance levels are expressed at.5 level. The gas prductin and IVDMD values, in general, were higher fr all srghum during the secnd year, indicating pssible envirnmental effects n digestibility. Average rainfall during the grwing seasn in Year I was abut I inch belw nrmal, but als 1.26 inches abve nrmal during the secnd year. Envirnmental effects are nt well understd. 1978 Animal Science Research Reprt 81