Gonda, Horacio
- Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA)
Sammanfattning
An experiment was completed to evaluate effects of two drying methods applied to faecal and herbage samples on estimation of n-alkane concentration and the calculated dry matter (DM) intake, faecal output (FO) and apparent in vivo DM digestibility (DMD). Four Holstein-Friesian steers (182 +/- 12.1 kg initial body weight) housed in individual pens were fed at 8:30 and 16:30 h with ryegrass (Lolium perenne L.) hay for 18 d. Refusals were removed and weighed every day at 8:30 h before morning feeding. From days 9 to 18, the steers were dosed twice a day at feeding time, with cellucotton stoppers containing C-32 (88.49 mg/pellet) and C-36 (87.12 mg/pellet). During the last 5 d of dosing, total collection of faeces was completed using harnesses. For the n-alkane analysis, faecal (n = 64) and offered hay (n = 4) samples were subdivided into two subsamples and prepared for two alternative drying methods: oven-drying at 60 degrees C (OD) or freeze-drying (FD). The n-alkane profiles of the offered and refused hay oven-dried at 60 degrees C did not differ. In offered hay subsamples, concentrations of n-alkanes were not affected by drying method. In faecal subsamples, drying method affected (P<0.05) concentrations of all n-alkanes, except for C-23, C-25 and C-35, as well as the ratios C-32:C-31 and C-32:C-33. There were no differences between estimated and measured values when DM intake and apparent in vivo DMD were estimated based on the ratio C-32:C-33. In contrast, when the ratio C-32:C-31 was used, estimated values either differed (P<0.02) or tended to differ (P<00.09) from measured values for OD and FD subsamples, respectively. Estimates of FO from subsamples OD and FD did not differ from measured values. Faecal recovery increased with increasing carbon-chain length in both drying methods. Results show that oven-drying at 60 degrees C could replace freeze-drying for sample dehydration to estimate DM intake and apparent in vivo DMD when ratio C-32:C-33 was used. However, due to the low number of replicates, further studies should be conducted before use of C-32:C-33 ratio in oven-dried samples can be recommended. (c) 2012 Elsevier B.V. All rights reserved.
Nyckelord
Steer; n-Alkane; Faeces; Oven-dried; Freeze-dried; Drying method
Publicerad i
Animal Feed Science and Technology
2012, volym: 177, nummer: 1-2, sidor: 1-6
Utgivare: ELSEVIER SCIENCE BV
SLU författare
UKÄ forskningsämne
Jordbruksvetenskap
Publikationens identifierare
- DOI: https://doi.org/10.1016/j.anifeedsci.2012.06.003
Permanent länk till denna sida (URI)
https://res.slu.se/id/publ/44131