Utilization of canola seed fractions in ruminant feeds

Abstract

Canola fibre-protein and can-sugar are the two by-products arising from a process for separating high quality protein fractions from canola meal. In the first trial chemical characteristics of fibre-protein and can-sugar were examined in comparison with commercial canola and soy meal. In the second trial in situ rumen degradability and kinetics of test feed was studied. Based on the findings of those two trials, available energy values were estimated based on NRC (2001) while protein contents potentially absorbable at small intestine were predicted using both NRC (2001) and DVE/OEB models. Subsequently a mixture of fibre-protein and can-sugar was used as an additive to dehydrated alfalfa pellet and two dairy cow trials were conducted to determine the palatability and examine effect on lactation performances of blended alfalfa pellet feeding in comparison with standard alfalfa pellet. Palatability difference was evaluated by “Paterson -two choice alternating access method” through a 7 day experimental period using 6 lactating Holstein cows. In the lactating performance trial, 6 cows were randomly assigned into two groups and two treatments were allocated over three experimental periods in a switchback design. Can-sugar consisted of water soluble components (CP 15.6 %DM; SCP 96.2 %CP; NFC 99.9 %CHO) with non-protein nitrogen as the main CP fraction (NPN 96.2 %CP). Fibre-protein was a highly fibrous material (NDF: 55.6%; ADF: 46.3%; ADL: 24.1%) comparing to canola meal (NDF: 25.4%, ADF: 21.2%, ADL: 9.0%) due to presence of higher level of seed hulls in fibre-protein. Comparing to canola meal, fibre-protein contained 9% less CP and 1/4 of that consisted of undegradable ADIP. Rumen degradability of can-sugar was assumed as immediate and total as it was water soluble. Most of the ruminally undegradable nutrient components present in canola meal appeared to be concentrated into fibre protein during the manufacturing process and as a result fibre-protein has shown a consistently lower effective degradability of DM, OM, CP NDF and ADF comparing to both canola and soy meal. Available energy content in can-sugar was marginally higher than that of canola meal while fibre-protein contained only 2/3 that of canola meal. The predicted absorbable protein content at small intestine was about 1/2 that of canola meal. These results indicate that fibre-protein can be considered as a secondary source of protein in ruminant feed and a mixture of fibre-protein and can-sugar would nutritionally complement each other to formulate into a cheaper ingredient in ruminant ration. In the palatability study, there was no significant difference (P>0.05) in intake preference or finish time between the blended and standard alfalfa pellets. The results from the lactation study showed that there was no significant difference (P>0.05) in milk yield, dairy efficiency or milk composition between the blended and standard alfalfa pellets. The results from the two studies indicated that fibre-protein and can-sugar fractions could be used as an additive to alfalfa dehydrated pellet at 15% inclusion rate without compromising its palatability or the performance of dairy cows. For future studies it is proposed to conduct feeding trials with varying levels of inclusions to alfalfa pellet to know the nutritional effect of fibre-protein and can-sugar while ascertain optimum inclusion rate.