Site and extent of digestion, duodenal flow, and intestinal disappearance of total and esterified fatty acids in sheep fed a high-concentrate diet supplemented with high-linoleate safflower oil

Abstract

Our objective was to determine duodenal and ileal flows of total and esterified fatty acids and to determine ruminal fermentation characteristics and site and extent of nutrient digestion in sheep fed an 80% concentrate diet supplemented with high-linoleate (77%) safflower oil at 0, 3, 6, and 9% of DM. Oil was infused intraruminally along with an isonitrogenous basal diet (fed at 2% of BW) that contained bromegrass hay, cracked corn, corn gluten meal, urea, and limestone. Four crossbred wethers (BW = 44.3 +/- 15.7 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 4 x 4 Latin square experiment, in which 14 d of dietary adaptation were followed by 4 d of duodenal, ileal, and ruminal sampling. Fatty acid intake increased (linear, P = 0.004 to 0.001) with increased dietary safflower oil. Digestibilities of OM, NDF, and N were not affected (P = 0.09 to 0.65) by increased dietary safflower oil. For total fatty acids (free plus esterified) and esterified fatty acids, duodenal flow of most fatty acids, including 18:2c-9,c-12, increased (P = 0.006 to 0.05) with increased dietary oil. Within each treatment, duodenal flow of total and esterified 18:2c-9,c-12 was similar (P = 0.32), indicating that duodenal flow of this fatty acid occurred because most of it remained esterified. Duodenal flow of esterified 18:1t-11 increased (P = 0.08) with increased dietary safflower oil, indicating that reesterification of ruminal fatty acids occurred. Apparent small intestinal disappearance of most fatty acids was not affected (P = 0.19 to 0.98) by increased dietary safflower oil, but increased (P = 0.05) for 18:2c-9,c-12, which ranged from 87.0 to 97.4%, and for 18:2c-9,t-11 (P = 0.03), which ranged from 37.9% with no added oil to 99.2% with supplemental oil. For esterified fatty acids, apparent small intestinal disappearance was from 80% for 18:3c-9,c-12,c-15 at the greatest level of dietary oil up to 100% for 18:1t-11 and 18:1c-12 with 0% oil. We concluded that duodenal flow of 18:2c-9,c-12 was predominately associated with the esterified fraction, suggesting that the extent of ruminal lipolysis was decreased with increased dietary high-linoleate safflower oil. Furthermore, biohydrogenation intermediates observed in the esterified fatty acids indicated that some reesterification occurred, and the high level of apparent absorption of esterified fatty acids indicated that intestinal lipolysis did not limit overall digestion of the fatty acids fed to the sheep.

Assessing rumen biohydrogenation and its manipulation in vivo, in vitro and in situ

“…Although lipolysis is a prerequisite of rumen BH, in vivo studies reporting dietary and digesta EFA and NEFA fractions are scarce [15][16][17]. Omasal or abomasal sampling offers the greatest opportunity for the correct assessment of rumen lipolysis, without the risk of intestinal hydrolysis.…”

Performance and digestibility characteristics of finishing diets containing distillers grains, composites of corn processing coproducts, or supplemental corn oil1

“…Plascencia et al (2003) explained that the low intestinal digestibility of fat is due to extensive ruminal biohydrogenation of fatty acids. Additionally, Atkinson et al (2006) indicated that feeding highconcentrate diets can result in decreased ruminal biohydrogenation, which can lead to greater unsaturated fatty acid concentrations in tissues. This, coupled with lower fat intakes may explain why cattle fed the CON and CON + OIL diets had greater total fat digestibility than cattle fed the COMP and COMP + OIL diets.…”

Effect of feeding calcium salts on performance of nursing Awassi ewes

“…Results of CP and NDF digestibilites are consistent with the findings of Manso et al (2006) who fed growing lambs diets containing calcium salts (MAGNAPAC) similar to the fat source used in the present study. Similarly, Atkinson et al (2006) observed no differences on OM, CP, and NDF digestibilities when crossbred whether lambs were fed high concentrate diets supplemented with high-linoleate safflower oil at levels of 0%, 3%, 6%, and 9%. However, our results for ADF digestibility disagreed with previous studies that reported that inclusion of fat decreased ADF digestibility (Reddy et al 2003;Appeddu et al 2004;Manso et al 2006).…”