Comparison of nutritive value of different protein sources resulting from the reaction of tannins extracted from raisin byproducts with corn-steep liquor in ruminant nutrition

Document Type : Research Paper

Authors

• Abolfazl Koolivand
• Arash Azarfar
• Amir Fadayifar
• Ayoub Azizi

Department of Animal Science, Faculty of Agriculture and Natural Resources, Lorestan University , Khorramabad, Iran

Abstract

Keywords

• Protonomix
• Phosphoprotanomix
• By-passed protein
• Corn-steep liquor
• Raisin by-product tannins

20.1001.1.20084773.1402.54.3.5.9

Main Subjects

• Animal Nutrition and poultry

Extended Abstract

Introduction

Nowadays, the price of feed commodities for all animal sectors are raising drastically for several reasons such as drought and international conflicts and disputes. To reduce feed costs and improve profitability, inclusion of agricultural by- or co-products in ruminants’ rations has drawn the attention of ruminant nutritionist worldwide. Corn-steep liquor is one of the main by-products of starch production from corn kernel with more the 4000 ton annual production in Iran. Despite its high protein and energy contents, its low pH, liquid from, high viscosity and high soluble protein content hamper its inclusion in ruminants’ rations. To avoid such problems, we recently manufactured two products, namely protanomix and phosphoprotanomix, which are brownish powders produced from precipitation of corn-steep liquor with tannins extracted from raisin by-products. Therefore, the present study aimed to determine the nutritive value and estimate the rumen protected-protein level of protanomix and phosphoprotanomix as two new protein sources and compare them with corn-steep liquor as a raw material for the production of these products.

Materials and methods

   To evaluate the protein sub-fractions of protanomix and phosphoprotanomix, their protein contents were fractionated according to the Cornell Net Carbohydrate and Protein System (CNCPS) According to CNCPS, protein is partitioned into non-protein nitrogen (A), true protein (B) and bound true protein (C). Based on their rates of degradation in the rumen, fraction PB is further partitioned into three sub-fractions called B1, B2 and B3. Fraction B1 is buffer-soluble protein precipitated by trichloroaceticacid and has a rapid ruminal degradation rate. Fraction B2 is insoluble in buffer but soluble in neutral detergent solution and has an intermediate ruminal degradation rate. Fraction B3 is insoluble in acid detergent but soluble in neutral detergent and has a slow ruminal degradation rate; a large part of it escapes rumen fermentation because of its association with plant cell walls. Acid detergent–insoluble protein (ADICP) is fraction C, which is extremely resistant to degradation by microbial and mammalian enzymes.

In an in vitro gas production system samples of corn-steep liquor, protanomix and phosphoprotanomix were incubated in 100-ml glass vials (7 vials as replicates) with a blend of strained rumen fluid obtained from two ruminally fistulated Lori rams and artificial saliva for 0, 2, 4, 6, 12, 16, 24, 48, 72 and 96 hours under the strict anaerobic condition to determine the kinetics of gas production. To determine rumen fermentation parameters, 16 hours after incubation, 3 vials of 7 vials from each treatment were chosen, their produced gas were recorded. The vials were then placed in the ice to terminate fermentation, and pH was determine immediately using a pH meter. The vials’ content were then centrifuged for 20 min at 2000 ×g. The supernatant was used to determine N-NH3 concentration. The resulting pellet was quantitatively transferred into the three-layer propylene bags, boiled in neutral detergent solution for 2 h, rainsed with distilled water, dried in a forced air oven and weighed to estimate in vitro truly degraded dry matter (IVTDDM). Data on IVTDDM and 16 h gas production were then used to estimate partitioning factor (PF), microbial protein synthesis (MPS) and efficiency of microbial protein synthesis (EMPS). Data on gas production after 16 h incubation (ml/200 mg of substrate DM) were used to estimate in vitro organic matter apparent digestibility (IVOMAD), metabilizable energy content and short chain fatty acids production

Results and discussion

The insoluble protein in protonomix and phosphoproteomix were 81.15 and 48.98 percent of crude protein, respectively; while this value was 13.10 percent in corn-steep liquor. Gas production throughout the incubation and potential of gas production were affected by the experimental treatments, so that the highest values were related to the control treatment (corn-steep liquor). All ruminal-fermentation parameters were affected by the experimental treatments, so that the lowest metabilizable energy (ME) and short chain fatty acids (SCFA) and the highest efficiency of microbial protein synthesis (EMPS) and pH belonged to phosphoprotanomix; the lowest amount of in vitro organic matter apparent digestibility (IVOMAD) and microbial protein synthesis (MPS) were related to protonomix; while the highest amount of in vitro truly degraded dry matter (IVTDDM) and ammonia nitrogen (N-NH3) and the lowest value of partitioning factor (PF) belonged to the control treatment.

Conclusions

    The results of current study show that protanomix and phosphoprotanomix have the potential to be included in ruminant’s rations as rumen undegraded protein and phosphorous sources (phosphoprotanomix). However, further animal trials are needed to evaluate the feasibility of using these products in practice.