EFFECTS OF DIETARY LEVEL OF BARLEY HULLS AND FIBER-TYPE ON PROTEIN AND ENERGY DIGESTIBILITIES OF CONDOR HULLESS BARLEY IN GROWING SWINE

Condor barley hulls were added by weight (0, 50, 100, 150 and 200 g kg (-1)) to Condor barley kernels to study the effect of added hulls and fibre level on apparent protein and energy digestibilities using the M obile Nylon Bag Technique (MNBT) with growing castrates. Twenty-four l -g samples of the hull-kernel mixtures and hulls alone were placed int o nylon mesh bags and were inserted through a simple T-cannula in the duodenum of six growing pigs using a 6 x 6 Latin square design. Bags w ere collected from faeces approximately 24-36 h after insertion and cl eaned. Samples were analysed for crude protein (CP), gross energy (GE) , and acid-detergent (ADF) and neutral-detergent (NDF) fibre. The addi tion of hulls to Condor kernels linearly increased ADF and NDF levels in the kernel-hull mixtures. Condor kernels had a crude protein (CP) c ontent of 142 g kg(-1); the apparent digestibility of protein was 88.6 %. The addition of hulls linearly decreased CP content (P < 0.01) and CP digestibility in a curvilinear fashion (P = 0.006), Condor kernels had a GE content of 17.6 MJ kg(-1) and a digestibility of 87.4%. Energ y digestibility coefficients decreased linearly (P = 0.27) as the prop ortion of hulls in the kernel/hull mixture was increased to 200 g kg(- 1). Regression models based on CP, GE, ADF and NDF were highly signifi cant and produced accurate estimates of protein and energy digestibili ty in the six Condor kernel-hull mixtures. Correlation coefficients re lating predicted CP and GE digestibilities in 25 barley samples using regression equations based on ADF or NDF and data from the kernel-hull mixtures and MNBT digestibilities were 0.53 (P = 0.006) and 0.79 (P = 0.0001) for CP and GE, respectively. Condor hulless barley represents a good source of digestible energy and protein for swine and digestib ility coefficients could be reliably predicted from regression models using chemical components as independent variables.