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In situ rumen degradability and intestinal digestibility of rumen-protected lysine products.

S. Calsamiglia




In situ rumen degradability and intestinal digestibility of rumen-protected lysine products.
F. Francia1, C. Faturi2, M. E. Rodriguez-Prado1, S. Calsamiglia*1. 1Animal Nutrition and Welfare Service, Univeristat Autonoma de Barcelona Bellaterra, Spain, 2Universidad Federal Rural de la Amazonia Belem, Brazil.

The objective of this study was to determine and compare rumen degradation and in vitro intestinal digestibility of 3 ruminally protected (RP) lysine products: LysiGEM and LysiPEARL (Kemin Animal Nutrition and Health); and AjiPro (Ajinomoto). Ruminal degradability and intestinal digestibility of different RP-Lys sources were studied using the in situ nylon bag technique and the modified 3-step in vitro technique, respectively. The RP-Lys products consisted of Lys coated with rumen-stable compounds. Samples (0.38 � 0.01 g) of each RP product were weighed into nylon bags and incubated in the rumen for 0, 2, 4, 8, 16, 24 and 48 h in duplicate bags for each incubation time in 2 consecutive experimental periods. An empty bag was also included as a correction factor for each sample at each incubation time. Ruminal degradability was calculated with a simple exponential function (Y = a+b*(1-exp(-ct)), where a was the amount of N disappearing from the bag at 0 h; b was the potentially degradable fraction; and c was the degradation rate of the potentially degradable fraction. The effective degradability of N (EDN) was calculated as: EDN (%) = a+[(b*c)/(c+k)]; where k (0.10/h) is the estimated rate of outflow from the rumen, and a, b, and c are the same as described earlier. Treatment effects adjusted by period were analyzed using the GLM of SAS (Cary, NC) and significance declared at P < 0.05. Solubility (%) was higher in LysiGEM (20.9) and LysiPEARL (26.8) compared with AjiPro (2.6). Rate of degradation (/h) was higher in LysiPEARL (0.048) compared with AjiPro (0.015) and LysiGEM (0.013). Effective degradation (%) was highest in LysiPEARL (49.2), intermediate in LysiGEM (21.4) and lowest in AjiPro (9.2). However, intestinal digestibility (%) was lowest in AjiPro (47.9) compared with LysiGEM (87.3) and LisiPEARL (95.3). Bioavailability (%) was highest in LysiGEM (63), intermediate in LysiPEARL (48.7) and lowest in AjiPro (44.5). There are relevant differences in ruminal degradability and intestinal digestibility of Lysine among different RP-Lys that have an important impact on overall bioavailability.

Keywords: protected lysine, ruminal degradability, intestinal digestibility.