Abstract #M299

# M299
Interactions between levels of flaxseed oil and corn grain particle size on milk fatty acid profile in Jersey cows.
V. Brossillon1, A. F. Brito*2, S. F. Reis2, D. C. Moura3, J. G. B. Galvão Jr.4, C. Côrtes1, A. S. Oliveira5, 1Ecole Supérieure d’Agricultures, Angers, France, 2University of New Hampshire; Department of Biological Sciences, Durham, NH, 3Programa de Pós Graduação em Ciência Animal; Universidade Federal de Mato Grosso, Cuiabá, MT, Brazil, 4Instituto Federal de Educação do Rio Grande do Norte, Ipanguaçu, RN, Brazil, 5Instituto de Ciências Agrárias e Ambientais, Universidade Federal de Mato Grosso – Campus Sinop, Sinop, MT, Brazil.

Flaxseed oil (FO) is the richest source of the essential n-3 fatty acid (FA) α-linolenic acid (ALA). We hypothesize that corn of 2 particle sizes [cracked corn (CC) vs. ground corn (GC)] and different degradation rates could interact with FO leading to shifts in ruminal biohydrogenation (BH) pathways that ultimately affect milk fatty acids (FA). Sixteen mid-lactation organically certified Jersey cows were randomly assigned to treatments in a replicated, factorial 4 × 4 Latin square design with 24-d periods. Treatments were fed as TMR (55:45 forage-to-concentrate ratio) consisting (DM basis) of (1) 0% FO + 28.3% CC, (2) 0% FO + 27.1% GC, (3) 3% FO + 28.3% CC, and (4) 3% FO + 27.1% GC. Diets averaged 19.5% starch, and 4.9 and 7.6% ether extract for 0 and 3% FO, respectively. Corn grain mean particle size averaged 2,047 µm (CC) and 580 µm (GC). Contrasts were used to compare: FO level, corn particle size, and oil × corn interaction. ALA was the only FA in milk that showed an oil × corn interaction (P = 0.02); cows fed 3% FO + GC showed the greatest proportion of ALA in milk (0.82 g/100 FA), and those fed 0% FO + CC the least (0.55 g/100 g FA). Except for c-9, c-12 18:2, all remaining milk FA increased with feeding 3% vs. 0% FO (Table 1). Increased milk 18-C FA with 3% FO may be explained by increased 18-C FA intake. Compared with cows fed CC, those fed GC had decreased 18:0 and c-9 18:1, and increased c-9, c-12 18:2, which may be linked to differences in FA profile and ruminal BH between corn sources. Overall, changes in milk FA profile appear to be largely influenced by level of FO supplementation or corn grain source, but not by the FO × oil interaction. Table 1. Milk FA profile
FA, g/100 gFlax oilCorn grainSEMContrasts (P > F)
c-9 18:115.318.717.416.60.33<0.001<0.001
c-9, c-12 18:22.021.831.871.980.05<0.001<0.01
t-10 18:10.190.320.260.260.01<0.0010.90
t-11 18:11.031.821.431.420.09<0.0010.99
c-9, t-11 18:20.360.570.470.460.02<0.0010.72

Key Words: corn grain, flax oil, milk fatty acid