1. The significance of study on protein digestion rate
Improving pig production performance is a profitable way to reduce the cost per kilogram of meat and increase profits. Diet is the most important factor in determining performance. Protein and energy are the two most important nutrients in the diet, and together they make up more than 90% of the total formula. Studies have shown that only when the digestion and absorption rates of protein and energy are synchronised can maximum deposition of the two nutrients be achieved in the animal.
Taking the current piglet feed as an example, the energy supply has adopted a typical combination of raw materials with fast (monosaccharide/ disaccharide), medium (fast starch) and slow (medium-slow starch and fat) digestion rates. The same rule should be applied to the protein supply: raw materials with fast (amino acids and small peptides), medium (medium and long chain peptides) and slow (complete protein) digestion. However, there is no systematic review data on the digestion rate of different protein materials.
2. Comparison on digestion rate of different protein
2.1 Study project
6 kinds of common protein ingredients in pig feed: Peruvian steamed fish meal, dehulled soybean meal, soy protein concentrate, extruded full-fat soybean, fermented soybean meal, enzymatic hydrolysate of soybean protein (Chengdu Mytech)
2.2 Method
Using the pepsin- trypsin digestion method to set different times, collect the digestive fluids to measure the nitrogen content, calculate the protein digestion rate and draw a graph.
2.3 Result
The law of in vitro protein digestion rate of different raw materials.
Peruvian steamed fish meal:
There was no significant difference in digestibility at 30, 60 and 90 min (P>0.05). However, digestibility increased significantly at 120, 180 and 240 min (P<0.05) and there was no significant difference in digestibility at 240 min (P>0.05).
Dehulled soybean meal:
There was no significant difference in digestibility at 30, 60 and 90 min (P>0.05),while digestibility increased significantly at 120 min and 150 min respectively (P<0.05). There was no significant difference in digestibility after 210 min (P>0.05).
Soy protein concentrate:
There was no significant difference in digestibility at 30, 60 and 90 min (P>0.05). Digestibility increased significantly at 120 min and 240 min respectively (P<0.05).
Extruded full-fat soybean:
There was no significant difference in digestibility at 30, 60, 90, 120 and 150 min (P>0.05). Digestibility increased significantly at 210 min (P<0.05), and there was no significant difference in digestibility after 240 min (P>0.05).
Fermented soybean meal:
There was no significant difference in digestibility at 30, 60, 90 and 120 min(P>0.05). Digestibility increased significantly at 150, 180 and 240 min respectively (P<0.05), and there was no significant difference in digestibility after 240 min (P>0.05).
Enzymatic hydrolysate of soybean meal:
There was no significant difference in digestibility at 30 and 60 min (P>0.05). Digestibility increased significantly at 90 min (P<0.05), and there was no significant difference in digestibility after 120 min (P>0.05).
In vitro digestibility of different protein at the same digestive time
Digestion for 90 min:
The digestibility of enzymatic hydrolysate of soybean meal was significantly higher than that of fish meal and dehulled soybean meal (P<0.05).
There was no significant difference in the digestibility of fish meal and dehulled soybean meal (P>0.05)
And the digestibility of soy protein concentrate, extruded full-fat soybean, and fermented soybean meal was significantly lower than that of dehulled soybean meal (P<0.05).
Digestion for 150 min:
There was no significant difference in the digestibility of enzymatic hydrolysate of soybean protein and dehulled soybean meal (P>0.05).
The digestibility of fish meal, soy protein concentrate, extruded full-fat soybean, and fermented soybean meal was significantly lower than that of dehulled soybean meal (P<0.05).
Digestion for 240 min:
There was no significant difference in the digestibility of enzymatic hydrolysate of soybean protein, dehulled soybean meal and fish meal (P>0.05).
The digestibility of soybean protein concentrate, extruded full-fat soybean and fermented soybean meal was significantly lower than that of dehulled soybean meal (P<0.05).
Digestion for 360 min:
There was no significant difference in the digestibility of enzymatic hydrolysate of soybean protein and dehulled soybean meal (P>0.05).
The digestibility of fish meal, soybean protein concentrate, extruded full-fat soybean and fermented soybean meal was significantly lower than that of dehulled soybean meal (P<0.05).
2.4 Analysis
Different proteins have different digestion rate
Enzymatic hydrolysate of soybean protein is digested rapidly in 1-2 hours.
Fish meal and dehulled soybean meal are digested at medium speed in 3-4 hours.
Soy protein concentrate, extruded full-fat soybean, and fermented soybean meal are digested slowly in 5-6 hours.
Different process alters the protein structure and digestion rate
Enzymatic hydrolysate process (enzymatic hydrolysate of soybean protein) increased the digestion rate and digestibility.
Alcohol leaching (soybean protein concentrate), puffing(extruded soybean) and fermentation (fermented soybean meal) decreased the digestion rate and digestibility.
3. Application
It is suggested to combine protein materials with different digestion rate in piglets feed. For example: enzymatic hydrolysate of soybean protein or amino acid (fast digestion speed) + fish meal or soybean meal (medium digestion speed) + soy protein concentrate or extruded full-fat soybean or fermented soybean meal (slow digestion speed).
The utilization of energy raw materials with varying digestion rates - fast, medium, and slow - can expedite piglet growth and enhance production performance to an optimal level.