Use of cashew and castor essential oils to improve fibre digestibility in high forage diets: digestibility, ruminal fermentation and microbial protein synthesis

Abstract

High forage diets in the tropics are less efficient and more contaminating due to high energy losses as methane and the low digestibility of tropical forages. The objective of the study was to determine the effects of essential oils (EO) of Anacardium occidentale and Ricinus communis as additives in high forage diets on intake, digestibility, ruminal fermentation and synthesis of microbial protein. Four ‘Holstein’ steers fitted with ruminal cannula were used in a 4 × 4 Latin square design (21-day period). The treatments were 1, 2, 4 and 8 g day-1 EO per animal (essential oils, Oligobasics®). The diet was total mixed ration (TMR) of Brachiaria hay (Brachiaria humidicola cv. Lanero) and concentrate (ground corn, soybean meal, ammonium sulphate, urea and minerals) in an 80:20 ratio. Differences were observed in the digestibility of neutral detergent fibre (NDF) and total digestible nutrients (TDN) in levels above 2 g day -1 EO (P < 0.05). The VFA (volatile fatty acids) acetate and propionate were higher in diets with 2 g day -1 EO (P < 0.05), without affecting the acetate:propionate ratio. Levels above 2 g day -1 EO negatively affected the faecal N excretion (P < 0.05). The inclusions of A. occidentale and R. communis EOs at 2 g day-1 per day animal improved fibre digestion and decreased N excretion. These results indicate that this mixture of EOs may have strong antimicrobial activity at lower doses. The N losses, fibre digestion and digestibility could be improved with the use of cashew and castor essential oils in high forage diets.

Assessing the In Vitro and In Vivo Effect of Supplementation with a Garlic (Allium sativum) and Oregano (Origanum vulgare) Essential Oil Mixture on Digestibility in West African Sheep

“…In an in vitro study with a 50:50 forage:concentrate ratio, the inclusion of 300 mg/L of garlic EO did not affect NDF digestibility [ 95 , 96 ]. The addition of EOs from Anacardium occidentale and Ricinus communis at inclusion rates of 1, 2, 4, and 8 g/day to a high-forage diet (80% Brachiaria humidicola hay ) resulted in improved fiber digestion and digestibility, among which the greatest improvement was observed at the lowest dose (2 g/day) [ 29 ].…”

“…Garlic ( Allium sativum ) and oregano ( Origanum vulgare ) EOs, or their main components (thymol, carvacrol, sulfur compounds, and allicin), could improve ruminal fermentation by reducing methane production [ 25 , 26 , 27 , 28 ], improving fiber digestion [ 29 , 30 , 31 ], and modulating ruminal populations and fermentation [ 32 , 33 , 34 ].…”

“…The effectiveness of EOs as additives may be greater at lower doses [ 29 , 30 , 35 , 36 , 37 ] and when used as a mixture for their synergistic effects [ 13 , 21 , 33 , 38 , 39 ], whereas higher doses could be detrimental to ruminal fermentation and populations [ 14 , 23 , 40 , 41 ]. Most previous studies on the effects of EOs on ruminants were conducted in vitro [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ].…”

Effect of amino acid supplementation and choline chloride for low protein diet on nitrogen efficiency and methane emission of dairy cows

“…At the presence of H 2 , as the basal substrate for ruminal methanogenesis (produced through multiple carbohydrate fermentation pathways) together with the volatile fatty acids (VFA) and CO 2 (Seshadri et al, 2018;Solden et al, 2018;Stewart et al, 2018), ruminal methanogens can use acetate, formate, ethanol and methyl compounds as substrates (Kelly et al, 2014;Henderson et al, 2015;Lambie et al, 2015;Li et al, 2016). Along with environmental concerns, it is believed that produced methane in the rumen cause an energy loss of about 2 to 12% in ruminants metabolizable energy (ME) which could consequently reduce total efficiency of the animal performance (Johnson & Johnson, 1995;Gill, Smith, & Wilkinson, 2010;Hynes, Stergiadis, Gordon, & Yan, 2016;Serrano, Cruz, Coneglian, & Branco, 2020). Since ruminants contribute in greenhouse gas emission, variety of programs are underway to decrease the methane production (Martin, Morgavi, & Doreau, 2010;Buddle et al, 2011;Kiggundu, Nantongo, Kayondo, & Mugerwa, 2019).…”