Animal Feed Science and Technology 271 (2021) 114762 Available online 22 November 2020 0377-8401/© 2020 Elsevier B.V. All rights reserved. An investigation of the nutritional value of camelthorn (Alhagi maurorum) at three growth stages and its substitution with part of the forage in Afshari ewes’ diets Mohsen Kazemi a, *, Kamal Ghasemi Bezdi b a Department of Animal Science, Faculty of Agriculture and Animal Science, University of Torbat-e Jam, Torbat-e Jam, Iran b Agricultural and Natural Resources Research and Education Center of Khorasan Razavi, Agricultural Research, Education and Extension Organization (AREEO), University of Torbat-e Jam, Mashhad, Iran A R T I C L E INFO Keywords: Camelthorn Forage Growth stage In vitro In vivo ABSTRACT The camelthorn (Alhagi maurorum: AM) is a drought-resistant plant belonging to the Fabaceae family, but its nutritional value has received little attention. First, the nutritional value of AM was investigated at three growth stages (vegetative, fowering, and seeding) by different laboratory and in vitro protocols. Second, the partial replacement of conventional dietary forage with AM on dry matter intake (DMI), milk yield and composition, nutrient digestibility, blood metabolites, and ruminal fermentation parameters of Afshari ewes were examined. Apart from ether extract (EE), other chemical compounds were all affected by three growth stages. Crude protein (CP) content ranged from 100 for the seeding stage to 122 g/kg DM for the vegetative stage. The concentration of minerals in the seeding stage was highest. At the vegetative, fowering, and seeding stages the values for relative feed value (RFV) were 112, 94.6 and 85.3, neutral detergent fber (NDF) were 449, 495 and 525 g/kg DM, and non-fber carbohydrates (NFC) were 351, 302 and 263 g/kg DM, respectively. The highest concentrations of total volatile fatty acids (TVFA, P = 0.002) and propionate (P = 0.010) were observed when AM at the vegetative stage incubated in the culture medium. The highest potential gas production (P = 0.002) and acid-base buffering capacity (P < 0.001) were also observed in the vegetative stage. The in vivo study indicated that the some nutrient (DM, OM) digestibility, milk yield and milk composition were unchanged when the conventional dietary forages were partially replaced with AM at the vegetative or fowering stages. Animal performance was affected by the growth stage when ewes fed a diet containing AM at the seeding stage compared to the control group. Ewes receiving AM at the seeding stage exhibited lower body weight change (P = 0.008), EE (P = 0.049), CP (P < 0.001) and NDF (P < 0.001) digestibility in comparison to the control group. The in vitro study showed that the nutritional value of AM at the vegetative stage was higher than the other stages. Partial Abbreviations: ADF, acid detergent fber; ADL, acid detergent lignin; ALT, alanine aminotransferase; AM, Alhagi maurorum; AST, aspartate aminotransferase; BHB, beta-hydroxybutyrate; BUN, blood urea nitrogen; BW, body weight; CP, crude protein; DIM, days in milk; DM, dry matter; DMD, dry matter digestibility; EE, ether extract; Hb, hemoglobin; MCH, mean corpuscular hemoglobin; MCV, mean corpuscular volume; ME, metabolizable energy; NDF, neutral detergent fber; NEl, net energy for lactation; NFC, non-fber carbohydrates; NH 3 -N, ammonia nitrogen; OM, organic matter; OMD, organic matter digestibility; PF, partitioning factor; RBC, red blood cells; RFV, relative feed value; TAC, total antioxidant capacity; TDMD, true dry matter digestibility; TOMD, true organic matter digestibility; TVFA, total volatile fatty acids; VFA, volatile fatty acids; WBC, white blood cells. * Corresponding author. E-mail address: phd1388@gmail.com (M. Kazemi). Contents lists available at ScienceDirect Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci https://doi.org/10.1016/j.anifeedsci.2020.114762 Received 2 July 2020; Received in revised form 17 November 2020; Accepted 19 November 2020