Effect of Cashew Nut Shell Liquid on Lactation Performance and Rumen Methane Production in Dairy Cows

Abstract Text: Technical cashew nut shell liquid (CNSL) is a by-product of the cashew nut industry in tropical countries, and is known to exhibit a wide range of biological activities, including inhibitory effect against gram-positive bacteria. This study was conducted to investigate the effects of CNSL (73.3% cardanol, 16.4% cardol, and 3.0% metilcardol) on DMI, milk yield and composition, rumen fermentation and CH₄ and CO₂ production, and nutrient digestibility in dairy cows. Eight multiparous Holstein cows (DIM, 140 ± 14 d; BW, 669 ± 47.8 kg) were used in a crossover design trial with two, 21-d periods. The TMR was based on corn silage and alfalfa haylage, and was formulated to meet or exceed the NE_L and metabolizable protein requirements of the cows (NRC, 2001). The diet contained (DM basis): 15.5% CP, 32.0% NDF, and 1.53 Mcal/kg NE_L. Treatments were: control (no CNSL supplementation), or 30 g/cow/d CNSL. The daily dose of CNSL was mixed with about 2 kg of TMR and top-dressed. Dry matter intake (average 26.6 ± 1.0 kg/d), 3.5% FCM (38.8 ± 1.6 kg/d), and milk composition (fat 3.32 ± 0.28% and true protein 3.09 ± 0.05%) were not affected by CNSL. Milk yield was numerically increased (P = 0.13) by CNSL (40.9 kg/d) compared with the control (39.0 kg/d). Rumen CO₂ production, measured using GreenFeed (C-Lock Inc., Rapid City, SD), was not affected by CNSL. Compared with the control, CNSL numerically decreased (P = 0.12) rumen CH₄ production (534 vs. 505 ± 39.6 g/cow/d, respectively) and CH₄ emission intensity (P =0.16; 13.3 vs. 12.3 ± 1.05 g/kg milk) and tended to decrease (P = 0.08) CH₄ production per kg of DMI (20.3 vs. 19.1 ± 0.83 g/kg). CNSL did not affect total tract apparent digestibility of nutrients, except NDF digestibility tended to be increased compared with the control (P = 0.09; 36.8 vs. 34.2 ± 1.47%, respectively). Total urinary N, urea N, and urinary purine derivatives excretions were not affected by treatment. MUN concentration was numerically increased (P < 0.13) in cows receiving CNSL (8.57 vs. 7.50 ± 0.62 mg/dL, respectively). Plasma urea and glucose concentrations were not affected by CNSL. In this study, CNSL tended to decrease rumen CH₄production per kg DMI and numerically increased milk yield without affecting DMI in dairy cows.

Keywords: cashew nut shell liquid, methane, dairy cow