Abstract #M268

# M268
Effects of oilseed supplementation on performance, methane emission and nitrogen utilization efficiency of lactating dairy cows.
C. Muñoz*1, R. C. Sánchez2, A. M. T. Peralta1, S. Espíndola3, T. Yan4, R. Morales1, E. M. Ungerfeld5, 1Instituto de Investigaciones Agropecuarias, INIA Remehue, Osorno, Chile, 2Facultad de Ciencias Veterinarias, Universidad de Concepción, Concepción, Chile, 3Cooperativa Agrícola y Lechera de La Unión, La Unión, Chile, 4Agri-Food and Biosciences Institute (AFBI), Agriculture Branch, Hillsborough, UK, 5Instituto de Investigaciones Agropecuarias, INIA Carillanca, Temuco, Chile.

Oilseeds can decrease enteric methane emission and affect nutrient utilization in dairy cows. The objective of this study was to evaluate the effects of oilseed supplementation on milk production and composition, methane emission and efficiency of nitrogen (N) utilization of dairy cows. Eight multiparous Holstein Friesian cows (75.4 ± 15.9 d in milk) were randomly allocated to treatments in a double 4 × 4 Latin square with 4 periods (22 d for adaptation and 6 d for measurements in digestibility units). Diets fed as TMR consisted of: maize silage, grass silage, a concentrate based on ground corn and soybean meal, and 1 of 4 treatments: control (CON; commercial fractionated palm oil protected fat; 3.5% DM basis), whole linseed (LNS; 7.5% DM basis), whole rapeseed (RPS; 6.9% DM basis) and whole cottonseed (CTS; 18.4% DM basis). Measurements of methane emissions were conducted using the SF6 technique. Data were analyzed using a mixed model including the fixed effects of treatment and period and the random effect of cow. The RPS diet increased (P < 0.05) DM intake compared with the other treatments. Treatments had no effect on milk yield. Milk fat content was decreased (P < 0.001) by LNS and RPS compared with CON. CTS tended to increase (P = 0.07) milk protein and increased (P < 0.001) milk lactose compared with CON, but was not different (P > 0.05) from LNS or RPS. Methane emission per cow (P < 0.001) and per kg of DM intake (P < 0.01), were decreased by CTS compared with RPS and LNS. Methane emission per kg of energy corrected milk (P = 0.03) was decreased by CTS compared with RPS, but was not different (P > 0.05) than CON and LNS diets. Total N intake was increased (P < 0.05) by RPS compared with CON. All oilseeds increased (P < 0.001) fecal N output (g/d) compared with CON. Feeding CTS increased (P < 0.001) urine N output compared with LNS, RPS and CON, and tended (P = 0.05) to decrease retained N compared with RPS. In conclusion, the inclusion of CTS in the diet of lactating dairy tended to increase milk protein and lowered methane emissions compared with LNS and RPS, but increased N excretion in urine.

Key Words: oilseeds, methane, cottonseed