Pig growth, gut health may see boost from protease supplements

Protease supplementation may improve the growth performance and gut development of weaned piglets, particularly those on fishmeal replacement diets, say Chinese researchers.

The authors, writing in the journal Animal Nutrition​​​, said the replacement of fishmeal by vegetable protein sources in piglet diets reduced the performance of the animals, unless a sufficient amount of supplemental protease was used.

The researchers found dietary protease supplementation in diets containing lower cost alternative ingredients may be a very promising way to reduce feed cost and make pork production more profitable.

“Dietary protease supplementation increases growth performance in weaned piglets, which may contribute to the improvement of intestinal development, protein digestibility, nutrient transport efficiency, and health status of piglets when fed with low digestible protein sources,”​ they concluded.

However, further investigations are required to understand interactions in digestive gut of pigs, with other supplemental enzymes and with dietary proteins, said the team.

Why protease?​

Little research has been done to understand the role that supplemental protease can play in the growth and development of weaned piglets, said the scientists, although, the supplement has been found to be helpful when used as part of an enzyme cocktail.

For example, Yin et al, (2001), found an enzyme blend including β-glucanase, xylanase and protease improved the digestibilities of crude protein and energy at ileal and the total tract levels of the hulless barley based diets for young piglets.

Similarly, that same time found an enzyme cocktail of arabinoxylanase and protease improved the nutritional value of diets containing wheat bran or rice bran for growing pigs, while Omogbenigun et al, (2004), saw that dietary supplementation with enzyme cocktails including proteases improved nutrient utilization and growth performance in weaned pigs. 

And Ji et al found a beta-glucanase-protease enzyme blend product improved the ileal digestibility of crude protein and other nutrients (Ji et al., 2008), while Jo et al (2012), found supplementation of 0.05% of enzyme cocktails — α-amylase, β-mannanase, and protease —  to a corn-SBM diet or a complex diet improved the performance of growing pigs. 

However the authors of this study said that although such positive effects have been reported, the contribution of protease on these improvements is still not clear.

The “efficacy of protease in weaned piglets and its mechanisms behind are still not clear especially when low digestible protein sources are used. Therefore, this study was conducted to investigate the effect of dietary supplementation with protease on the growth performance, nutrient digestibility, intestinal morphology, digestive enzymes and gene expression in weaned piglets,” ​they said.

Experiment details​

During the experiment, 300 piglets were fed one of five diets for a period of 14 days, said researchers. Piglets were housed in environmentally controlled rooms and diets and water were continually available.

The five included the standard commercial diet, named as the positive control (PC) diet that included 22.21% soybean meal, 5% whey protein and 3% fish meal, a negative control (NC) diet which was made up of 30.06% soybean protein without whey protein and fish meal, a 100 mg protease/kg NC diet, a 200 mg protease/kg NC diet, and a 300 mg protease/kg NC diet.

“The five diets were iso-nitrogenous and iso-caloric, and pelleted at a condition of 0.4 MPa and 75°C,”​ said researchers. “The major source of protein in the PC diet was from fishmeal and concentrated whey protein, which were substituted with soybean meal in the NC diet.”​

Body weights (BW) and feed intake was measured throughout the experiment and average daily gain (ADG), average daily feed intake (ADFI), the feed to gain ratio and a diarrhea index were determined, they said. Blood and fecal samples also were taken.

Additionally, at the conclusion of the feeding experiment, the intestine was collected along with stomach digesta and pancreatic samples, said the authors.

Results​

The positive control diet and the diets containing 200 or 300mg of supplemental protease had the most positive results, said the scientists. The diets increased “final body weight, ADG, ADFI, crude protein digestibility, enzyme activities of stomach pepsin, pancreatic amylase and trypsin, plasma total protein, and intestinal villus height,”​ when compared to the NC diet, they added.

The diets including 200mg and 300mg of protease also increased the villus height to crypt depth ratio for duodenum, jejunum and ileum when compared to the levels found in pigs getting the NC diet, they said.

The feeds with the higher levels of supplemental protease and the PC diet also saw a lower feed to gain ratio, diarrhea index, blood urea nitrogen and reduced diamine oxidase, reported the authors.

“Our results showed that the majority of the measured variables responded to protease supplementation in a dose-dependent manner. This indicates that 200 mg protease/kg NC diet supplementation would be more economically feasible under the resent experimental condition.​

The results were consistent with the previous study that supplementation of a neutral protease in barley/wheat/soy-based diets improved feed efficiency (O’Doherty and Forde, 1999),” ​added the team.

The researchers concluded that the replacement of fishmeal by vegetable protein reduced the growth performance of piglets, the digestibility of crude protein, and digestive enzyme activities, in findings consistent with previous work. And they said the protease additions improved nutrient utilization efficiency and growth performance.