Kinetic parameters of in situ degradability of crop residues in alpacas (Vicugna pacos)

Abstract

The aim of this study was to determine the kinetic parameters of the in-situ degradability of dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of crop residues (CR) of barley (Hordeum vulgare L), oats (Avena sativa L), peas (Pisum sativum L), quinoa (Chenopodium quinoa W) and beans (Vicia faba L) from the Huancavelica area, Peru. Two fistulated alpacas in the first stomach compartment were used. For the statistical analysis, the blocks were represented by the alpacas, the treatments by the CR and the subplots by the incubation times. Grounded CRs (5 g) were placed in nylon bags and incubated for 0, 12, 24, 48 and 72h, and the analysis of DM, CP and NDF was conducted. The parameters of degradability were estimated by non-linear regression D(t) = a+b(1-exp(-c*t)), the potential degradability was determined by D(p) = a+b, and effective degradability by D(e) = a+(b*c)/(c+k). Oats and quinoa had the highest DM percentages. CP content ranged from 2% for barley to 14.1% for beans. The NDF content was 34.94 % for beans, reaching 90.19 % for barley. There was an interaction effect of CR and incubation time on the degradability of the DM, CP and NDF. The degradability of these nutrients was influenced by the crop residues. The highest D(p) of the DM was for the pea (82.96%), followed by oats (79.26 %) and beans (75.47 %). The D(e) of the NDF was higher for beans of 37.96, 33.33 and 31.13 % in the passage rates of 3, 5 and 7 %/h, respectively. The high non-degradable fraction of the NDF (40.20 %) of the quinoa is highlighted and, therefore, the low D(p) of the DM (49.13%). The content of NDF and its kinetic characteristics exert a marked effect on the digestion of the CR under study.