Energy content and amino acid digestibility of extruded and dehulled-extruded corn by pigs and its effect on the performance of weaned pigs

Abstract

ABSTRACT:Three experiments were conducted to compare raw corn, extruded corn, and dehulled-extruded corn in piglets' feeding. In Experiment (Exp.) 1, 8 barrows (19.9 ± 0.6 kg) were fed experimental diets containing one out of three corn samples and a rice-soybean meal basal diet in a double 4 × 4 Latin square design to determine the digestible energy (DE) and metabolizable energy (ME) in the corn samples using the difference method. The DE content in extruded (14.29 MJ/kg) and dehulled-extruded (14.42 MJ/kg) corn was greater (P < 0.05) than in raw corn (13.57 MJ/kg). In Exp. 2, 5 barrows (26.2 ± 1.3 kg) were fitted with ileal T-cannulas and used in a 5 × 5 Latin square design to determine the apparent (AID) and standardized (SID) ileal digestibility of amino acids (AA). The diets comprised the basal diet, the three corn diets from Exp. 1, as well as a nitrogenfree diet to estimate basal endogenous losses of AA. The AID and SID of isoleucine, leucine, lysine, threonine, and valine in dehulled-extruded corn was lower (P < 0.05) than in raw or extruded corn. In Exp. 3, 108 weaned 35 days old piglets (8.4 ± 1.2 kg) were allotted to one of the three diets based on corn type. Weaned pigs fed diets containing extruded or dehulled-extruded corn exhibited reduced (P < 0.05) weight gain and feed intake than pigs fed diets containing raw corn. The diet containing dehulled-extruded corn resulted in a higher incidence of diarrhoea. In summary, extrusion of corn did not result in improvements in digestibility and dehulling corn prior to extrusion appeared to result in heat damage which reduced ileal digestibility of AA. Substitution of raw corn with extruded or dehulled-extruded corn in starter diets formulated to equal quantities of ME and SID AA content did not improve the performance of weaned pigs.

Effects of corn processing on piglet performance and intestinal parameters

“…In the present work, corn grinding and extrusion resulted in a similar performance, consistent with other studies that also did not find the extrusion process to result in better pig growth performance than grinding (Oliveira et al, 2011;Liu et al, 2014;Veum et al, 2017). Extrusion is generally believed to provide superior performance due to its improvement in nutrient digestibility (Medel et al, 1999;Rojas et al, 2016).…”

“…Greater villus height and villus:crypt ratio are indicative of higher surface area and cell ability to produce digestive enzymes and increased absorptive capabilities (Pluske et al, 1996;Wang et al, 2017). Thus, our findings reinforce that extrusion improves digestion and absorption of the nutrients (Medel et al, 1999;Liu et al, 2014), even when compared with ground ingredients with similar particle sizes.…”

“…This improvement is likely due to the higher starch digestibility provided by the extrusion process, increasing intestinal nutrient uptake as well as reducing the fraction of carbohydrates potentially harmful to the epithelium (Fadel et al, 1988;Rojas et al, 2016). The extrusion may also increase the digestion of non-starch polysaccharides and, although the fiber content of corn is low, approximately 50% of the total dietary fiber in corn-based diets may be attributed to corn (Liu et al, 2014). In addition, thermal processing acts to reduce pathogen concentration in the diet, a condition that favors the digestive tract epithelium (Kelley and Walker, 1999;Okelo et al, 2008).…”

“…However, after extrusion, corn is milled in smaller sieves, which makes it difficult to determine if the quality of the ingredient is due to the extrusion or fine-milling process. Performance or digestibility improvements in piglets due to corn extrusion have been previously reported (Medel et al, 1999;Rojas et al, 2016), whereas other reports found no benefits (Oliveira et al, 2011;Liu et al, 2014). However, none of these authors specifically investigated particle size of milled vs. extruded corn, nor investigated the possible effects of processing on intestinal development.…”