Effects of dietary protein sources differing in solubility on total tract and ileal apparent digestibility of nitrogen and pancreatic enzymes activity in early weaned pigs

Abstract

Abstract A digestibility trial involving 28 castrated male piglets from seven litters weaned at 21 days of age was conducted to examine total tract apparent digestibility (TTAD) and ileal apparent digestibility (IAD) of nitrogen. Four experimental diets based on manioc starch were compared, containing 21.8% crude protein of different physical properties supplied either by casein (C), soluble fish protein concentrate (SFPC), soyabean meal (SBM) or soyabean meal concentrate (SBMC). Insoluble N represented more than 90% of total N in casein, soyabean meal and soyabean concentrate; opposite to that, approx. one-third of N was either insoluble, or alcohol soluble or TCA soluble. The percentage of the different protein fractions in the digesta at the end of the ileum was not affected by the source of protein. The TTAD of nitrogen in diets containing C, SFPC, SBM or SBMC was 93.3, 89.5, 81.1 and 89.8%, respectively. The corresponding values for IAD were 87.7, 79.1, 72.5 and 84.2%, respectively. Compared to animals fed casein diet, weight of pancreas and total activity of chymotrypsin were reduced in those fed the SFPC diet by 36 and 56%, respectively. Diets containing SBM or SBMC caused a reduction of 6 (NS) and up to 35% (NS) in the weight of pancreas and the total activity of chymotrypsin, respectively. Results suggested that the only use of a highly soluble protein source in the starter diet reduces the development of the digestive process in particular the biosynthesis of the enzymes in the pancreas of the weaned piglet.