Artigo
Effect of replacing calcium salts of palm oil with camelina seed at 2 dietary ether extract levels on digestion, ruminal fermentation, and nutrient flow in a dual-flow continuous culture system
Autor
Marcondes, M. I.
Shenkoru, T.
Brandao, V. L. N.
Dai, X.
Paula, E. M.
Silva, L. G.
Poulson, S. R.
Faciola, A. P.
Institución
Resumen
Camelina is a drought- and salt-tolerant oil seed, which in total ether extract (EE) contains up to 74% polyunsaturated fatty acids. The objective of this study was to assess the effects of replacing calcium salts of palm oil (Megalac, Church & Dwight Co. Inc., Princeton, NJ) with camelina seed (CS) on ruminal
fermentation, digestion, and flows of fatty acids (FA) and AA in a dual-flow continuous culture system when supplemented at 5 or 8% dietary EE. Diets were randomly assigned to 8 fermentors in a 2 × 2 factorial arrangement of treatments in a replicated 4 × 4 Latin square design, with four 10-d experimental periods consisting of 7 d for diet adaptation and 3 d for sample
collection. Treatments were (1) calcium salts of palm oil supplementation at 5% EE (MEG5); (2) calcium salts of palm oil supplementation at 8% EE (MEG8); (3) 7.7% CS supplementation at 5% EE (CS5); and (4) 17.7% CS supplementation at 8% EE (CS8). Diets contained 55% orchardgrass hay, and fermentors were fed 72 g of dry matter/d. On d 8, 9, and 10 of each period, digesta effluent samples were taken for ruminal NH 3 , volatile fatty acids, nitrogen metabolism analysis, and long-chain FA and AA flows. Statistical analysis was performed using the MIXED procedure (SAS Institute Inc., Cary, NC). We detected an interaction
between FA source and dietary EE level for acetate,
where MEG8 had the greatest molar proportion of acetate. Molar proportions of propionate were greater and total volatile fatty acids were lower on CS diets. Supplementation of CS decreased overall ruminal nutrient true digestibility, but dietary EE level did not affect it. Diets containing CS had greater biohydrogenation of 18:2 and 18:3; however, biohydrogenation of 18:1 was greater in MEG diets. Additionally, CS diets
had greater ruminal concentrations of trans-10/11 18:1
and cis-9,trans-11 conjugated linoleic acid. Dietary EE
level at 8% negatively affected flows of NH 3 -N (g/d),
nonammonia N, and bacterial N as well as the overall
AA outflow. However, treatments had minor effects
on individual ruminal AA digestibility. The shift from
acetate to propionate observed on diets containing CS
may be advantageous from an energetic standpoint.
Moreover, CS diets had greater ruminal outflow of
trans-10/11 18:1 and cis-9,trans-11 conjugated linoleic
acid than MEG diets, suggesting a better FA profile
available for postruminal absorption. However, dietary
EE at 8% was deleterious to overall N metabolism and
AA outflow, indicating that CS can be fed at 5% EE
without compromising N metabolism.