Processing to Increase the Nutritive Value of Canola Meal
There is a general assumption that
there are benefits in the form of higher milk production and increased
feed utilization from decreasing protein degradability in CM (Gonda
et al 1994 {856}). The increased rumen undegradable protein and
the availability of this rumen escape protein for absorption in
the lower gastrointestinal tract may benefit rapidly growing calves
and high producing dairy cows (Moshtaghi and Ingalls {937}; Bell
1993 {907}; Robinson et al. 1994 {860}). Bell (1993 {907}) stated
that the technology for production of CM that possesses maximum
nutritional value for ruminants has yet to be developed. However,
treatments of CM have included adding formaldehyde treatment (FA),
sodium hydroxide, acetic, formic, propionic and hydrochloric acids,
whole fresh blood, fish hydrolysate, heat, moist heat, tallow
and extrusion (Mir et al. 1984 {1230}; Moshtaghi Nia and Ingalls
1992 {937}; Moshtaghi Nia and Ingalls 1995 {822} {827}; McKinnon
et al 1991 {999}; Khorasani et al. 1993 {899} and many others).
Moist heat treatment is an effective
process used to increase the rumen escape of CM protein without
adverse effects on protein digestibility in the lower gastrointestinal
tract (Moshtaghi and Ingalls 1992 {937}). Moist heat treatment
of CM at 127 C for 15 min reduced rumen degradability of CP (Moshtaghi
Nia and Ingalls 1992 {937}; Moshtaghi Nia and Ingalls 1995 {822})
and AA (Moshtaghi Nia and Ingalls 1995 {827}) with a corresponding
increase in the lower GI tract digestibility. Heat treatment
of protein sources decreases protein solubility by creating crosslinkages
between peptide chains and carbohydrates, increasing their resistance
to proteolysis. Chemical analysis of heated CM indicated a reduction
in soluble N (75% with 15 min), sucrose and GL content (19.07
to 0.78 mol GL/g DM) and an increase in ADIN (4.2 to 5.5% of total
N with 15 min.). Heating of the CM reduced essential AA, lysine
and arginine. Moist heat treatment reduced ruminal degradation
of DM and N, thereby increasing the amount available to the lower
GI tract. At 10 hr rumen incubation time reduced DM and N disappearance
in the rumen by 51 and 74%, respectively, while it increased the
proportion of DM and N digested in the lower GI tract by 169%
and 222%, respectively. Heating increased N disappearance in
the small intestine by 2.4-2.5 times with 16 hr incubation (Moshtaghi
Nia and Ingalls 1992 {937}; Moshtaghi Nia and Ingalls 1995 {822}).
Heat treatment increased by more than 300% the amount of rumen
escape protein that disappeared in the lower GI tract. With heating
times of 15 and 30 min total tract digestibility of DM and N were
not different than the control. Moist heat treatment for 15 min
increased ruminal escape of AA in CM, resulting lactating cows
fed heat treated CM having twice the AA reaching the small intestine
compared to cows fed conventional CM. Excessive heat and treatment
for 45 min reduced the AA, DM and N digestibility in the lower
GI tract (Moshtaghi Nia and Ingalls 1995 {827}; Moshtaghi Nia
and Ingalls 1995 {822}; Moshtaghi Nia and Ingalls 1995 {827}).
More recently, Dawowski et al. (1996 {807}) reported a moist-heat
treatment of CM at 130, 140 and 150C at 15 and 20% moisture.
Rumen degradability was reduced from 73 to 56% with 130C and 15-20%
with the higher temperatures. The proportion of protein digested
in the intestine was higher (38%) for RSM meals treated than for
untreated (21%) and the total digestibility remain unchanged.
Similar results were reported by McKinnon et al. (1991 {999}).
In agreement, a study by Vanhatalo et al. (1995 {829}) reported
four RSM varieties treated with Opex increased the proportion
of rumen-undegradable N in RSM without adversely affecting subsequent
intestinal digestibility. Variety had little influence on intestinal
N digestibility. Heat treatment increased the intestinal disappearance
of AAN and individual EAA. Gonda et al. (1995 {813}) reported
apparent total tract digestibilities were not affected by the
process of Expro on RSM-00 to reduce rumen N degradability from
72 to 52%. The conclusion was that a reduction in N intake in
dairy cows may be possible without impairing microbial N flow
to the duodenum and milk performance. A quick heat treatment
(less than 30 seconds), the ExPro, developed in Sweden reduces
rumen N solubility without any influence on either pepsin soluble
CP, ADF-N or lysine content. Over an average year this process
reduced CP rumen degradability from 72 to 46% without a decrease
in intestinal digestibility (82% untreated and treated). Treatment
increased the AAT by 60% or on average from 112 to 178 AAT (amino
acids presented to the small intestine) g/kg (Herland 1996 {803}).
The ExPro meal is palatable and is fed to cows at a rate of 1-4
kg/d/c or at 25% of the concentrate mixture. It is marketed as
an equivalent to SBM. Not only does this process sound remarkable,
but also performance results have been positive (table 11) (Tuori
and Syrjala-Qvist 1988 {1093}; Herland 1996 {803}).
Many studies report a decrease in rumen CP degradability
with the application of FA (Krastanova et al. 1994 {847}; 1995
{841}; Subuh et al. 1996 {798}; 1994 {850}; Antoniewicz et al.
1992 {952}; Bailey and Hironaka 1984 {1221}). Formaldehyde (0.6%
for RSM and 0.8% SBM/meal CP) treatment influenced the degradation
characteristics of DM and N for RSM and SBM. The rapid digestible
fraction (a) decreased (P < 0.05), the slowly digestible fraction
(b) increased (P < 0.05) and the fractional rate (c) decreased
(P < 0.05). The reduction in protein degradability of FA-treated
RSM was mainly due to a reduction in the fast degradable fraction
(Yao et al. 1992 as cited by Liu et al. 1993 {905}). The 48 hr
DM degradability of RSM, FA-RSM, SBM and FA-SBM was 81.0, 73.4,
88.1 and 79.3%. The 48 hr CP degradability of RSM, FA-RSM, SBM
and FA-SBM was 88.3, 75.5, 91.3 and 59.4% (Liu et al. 1993 {905}).
Solubility of RSM protein reduced from 65% to 5% with the application
of FA. Increased amounts of non-ammonia N entered the small intestine
with FA treated RSM supplemented to a silage diet (Liu et al.
1993 {905}). Conversely, Krastanova et al. (1995 {841}) reported
no change in the amount of NAN and AA reaching the duodenum, this
resulted from a lower AA content in the TRT-RSM and the tendency
towards lower microbial synthesis in the rumen. The protein from
the protected RSM was digested less readily in the rumen and in
the small intestine when bulls were fed RSM protected by FA (Kowalczyk
and Otwinowska 1982 {1254}). Rae et al. (1983 {1248}) reported
that FA treatment destroyed 58% of CM tyrosine and 29% lysine,
increased absorption of AA from the gut without an increase in
milk yield. Overprotection of canola and soybean proteins with
FA was also reported by Mir et al. (1984 {1230}). Formaldehyde
treatment with 10 and 20 g FA/kg CP was almost completely compensated
for by intestinal digestion in cannulated cows, but concentrations
of 30-40 g FA/kg CP had reduced intestinal and enzymatic CP digestibility
(Antonniewicz et al. 1992 {952}). Treatment of RSM with FA increased
heifer ADG (14.9%; P < 0.05) and improved feed conversion.
Formaldehyde treatment did not decrease the digestibility of
nutrients in RSM and the efficiency of N utilization was improved
(Liu et al. 1993 {905}). Digestibility trials by Subuh et al.
(1996 and 1994 {798}; {850}) compared protein sources (high and
low GL RSM, SBM) and protein treatments (FA and heat) for rumen
degradability and intestinal digestion. A lower rumen protein
degradability was reported for the low GL-RSM compared to the
high GL-RSM (83.6 vs. 86.2%, untreated, 56.8 and 60.8% for the
FA-treated, 82.6 vs. 86.0% for the heat treated)(Subuh et al.
1994 {850}). The total tract digestibility of N was higher for
SBM than high GL-RSM and low-GL RSM (P < 0.05) and were 95.1,
83.4, and 82.2% untreated, 89.5, 73.4 and 83.8%-FA treated and
95.4, 79.9 and 83.7%-heat treated. Performance data using FA-RSM
or CM has been variable (table 11). The use of FA is likely to
be limited as small amounts of FA have been reported in milk of
cows fed FA-treated feeds in some studies (Macleod et al. 1984
{1231}) and not others (Strzetelski et al. 1988 {1112}).
Khorasani et al. (1989 {1059}) treated CM with HCL,
acetic acid, formic acid or propionic acid and all acid treatments
decreased ruminal CP degradability without a negative effect on
intestinal digestibility (except HCL). McKinnon et al. (1991
{999}) added formic and acetic acid to CM and reported that there
was no influence on the protein fraction in the rumen. Robinson
et al. (1994 {860}) used Holstein cows in midlactation and fed
a diet containing four isonitrogenous diets that included 12%
CM. Normal CM was replaced by acetic acid treated CM in the amount
of 0, 33, 67 and 100%. Supplementation of acetic acid had a minor
influence on the undegradable protein fraction. Conversely, Khorasani
et al. (1993 {899}) reported that acetic acid was able to reduce
CP degradation in the rumen (83 vs. 59%) by decreasing both the
size of the soluble CP fraction and the rate of degradation of
the potentially degradable CP fraction. Protein that had been
treated was highly digestible in the intestine (Khorasani and
Kennelly 1991 {995};Khorasani et al. 1988 {1082}).
| Table 11. Performance of ruminants supplemented with treated CM compared to untreated and other protein sources | ||
|---|---|---|
| Reference | Diet | Performance |
| Formaldehyde | ||
| Rae et al. 1983 {1248} | Mixed diets with 13 or 23.5% CM and FA (12g/kg) or none fed to dairy cows in early lactation | FA-CM had no effect on milk yield, composition, DMI, apparent digestibility of DM, N or ADF. FA rumen NH3-N levels. |
| Ha and Kennelly 1984 {1220} | Four protein sources, FM, CM, FA-CM and blood treated-CM | FA milk production, DMI and protein intake-FA may have FI and/or digestibility in the lower GI tract |
| Strzetelski et al. 1988 {1112} | High SBM, high GL-RSM and RSM-00, FA at 40 g/kg CP or none (dietary CP was 15%) | milk production and fat and C18:2 content with FA vs. no-FA |
| Moist-heat | ||
| Herland 1996 {803} | Early lactating cows fed 4 concentrates, 14.3 and 19% CP treated and untreated | milk production with dietary CP and with Expro trt for the low CP diet (24.9 vs. 27.1 kg/d)-no diff. with high CP diet |
| Gonda et al. 1994 {856} Expro | Diets with 14.3 or 19% CP using 25% or 8% RSM-00 of concentrate, half heated and the other half not | Heat EPD from 72 to 52% resulting in milk production and feed utilization reducing N waste and dietary CP milk production |
| Tallow | ||
| Vicente et al. 1984 {1219} | -3 isonitrogenous concentrates, 8% SBM-tallow, 0%, 8% CM-tallow | Tallow supp. milk production (P<0.05) and fat, plasma NEFA, but milk protein |
The addition of 5 or 10% lignosulfonate to CM decreased
the CM CP in situ without a substantial increase in indigestible
protein as estimated by ADIN. This decrease in degradation of
CM was also accomplished by heating CM at 100 C (McAllister et
al. 1993 {928}).