Abstract #M277

Section: Ruminant Nutrition
Session: Ruminant Nutrition I
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Exhibit Hall B

# M277
Interactions between levels of flaxseed oil and corn grain particle size on milk yield and nutrient digestibility 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, Ipanguaçu, RN, Brazil, ⁵Instituto de Ciências Agrárias e Ambientais, Universidade Federal de Mato Grosso – Campus Sinop, Sinop, MT, Brazil.

Organically certified cows in the United States must have year-round access to the outdoors to comply with the National Organic Program rules. Thus, increasing dietary energy via flaxseed oil (FO) may be an attractive strategy to improve milk yield during the winter season. In addition, FO may interact with corn grain of 2 particle sizes [cracked corn (CC) vs. ground corn (GC)] to modulate nutrient digestibility ultimately affecting DMI and milk yield. 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) and consisted (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. Data are presented in Table 1. DMI and yields of milk fat and protein were not affected by treatments. Cows fed 3% FO produced more milk than those fed no FO. Conversely, concentrations of milk fat and protein, and total-tract aNDFom digestibility decreased with feeding 3% FO vs. 0% FO. Total-tract digestibilities of OM and starch were greater in cows fed GC than CC. Overall, FO appears to be viable strategy to increase milk yield during the winter season when cows are housed outdoors. Table 1. Milk yield and composition and total-tract digestibility of nutrients

Item	Flax oil		Corn grain		SEM	Contrasts (P > F)
Item	0%	3%	Cracked	Ground	SEM	Oil	Corn
DMI, kg/d	16.3	15.9	16.1	16.0	0.44	0.77	0.21
Milk yield, kg/d	17.1	18.2	17.6	17.6	0.55	<0.01	0.98
Milk fat, %	5.26	5.11	5.22	5.15	0.10	0.05	0.33
Milk fat, kg/d	0.87	0.90	0.89	0.88	0.02	0.16	0.56
Milk protein, %	3.63	3.45	3.54	3.54	0.07	<0.001	0.97
Milk protein, kg/d	0.60	0.61	0.60	0.61	0.02	0.73	0.77
OM digestibility, %	62.7	61.8	60.0	64.5	0.89	0.42	<0.001
aNDFom digestibility, %	46.5	42.1	44.5	44.2	1.05	<0.01	0.81
Starch digestibility, %	93.0	93.9	89.0	97.9	0.75	0.29	<0.001

Key Words: corn grain, dairy cow, flaxseed oil