Water regimes in selected fodder radish (Raphanus sativus) genotypes: Effects on nutritional value and in vitro ruminal dry matter degradability

Lusanda Ncisana; Tafadzwa Mabhaudhi; Ntuthuko Raphael Mkhize; Khuliso Ravhuhali; Tlou Julius Tjelele; Melvin Kudu Nyathi; Lwando Mbambalala; Ntokozo Happy Msiza; Mpho Siennah Nzeru; Albert Thembinkosi Modi

doi:10.1016/j.heliyon.2024.e29203

Water regimes in selected fodder radish (Raphanus sativus) genotypes: Effects on nutritional value and in vitro ruminal dry matter degradability

Heliyon. 2024 Apr 3;10(8):e29203. doi: 10.1016/j.heliyon.2024.e29203. eCollection 2024 Apr 30.

Authors

Affiliations

¹ Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, P/Bag X01, Scottsville, Pietermaritzburg, 3209, South Africa.
² Agricultural Research Council, Animal Production, P/Bag X02, Irene, 0062, South Africa.
³ Department of Mathematics, Science and Technology Education, University of Limpopo, Sovenga, Polokwane, 0727, South Africa.
⁴ Animal and Poultry Science, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, P/Bag X01 Scottsville, Pietermaritzburg, 3209, South Africa.
⁵ Department of Animal Science, School of Agricultural Sciences, Faculty of Natural and Agricultural Sciences, Northwest University, Mmabatho, 2735, South Africa.
⁶ Food Security and Safety Niche Area, Faculty of Natural and Agricultural Sciences, North-West University, Mmabatho, 2735, South Africa.
⁷ Agricultural Research Council, Vegetables and Ornamental Plants (ARC-VOP), Private Bag X 293, Roodeplaat, Pretoria, 0001, South Africa.

Abstract

Fodder radish is widely used as a livestock supplement, however, the nutritional value of fodder radish under different water conditions remains insufficiently understood. This study aimed to assess the chemical components and in vitro, ruminal dry matter degradability of two fodder radish genotypes (Endurance and Line 2) subjected to three irrigation regimes: well-watered (W1), moderate water stress (W2), and severe water stress (W3). The analysis revealed statistically significant effects of the main factors on the chemical composition and estimates of fodder radish leaves and tubers, particularly in terms of Crude Protein (CP) and Ether Extract (EE) across genotypes. Both Endurance and Line 2 leaves exhibited interaction effects on N, P, Ca, Mg, K, Na, Fe, Zn, Cu, Mn and Al. Meanwhile only Na, K, Zn, and Cu were affected in tubers. Endurance tubers, specifically, displayed significantly higher (p < 0.05) CP content, with Line 2 tubers showing the highest CP content under W1. Furthermore, Endurance leaves had higher levels of Neutral Detergent Fibre, EE, and Non-Structural Carbohydrate (NSC) compared to Line 2 leaves under W1. Notable differences in tuber fibres were found, specifically in Acid Detergent Fibre for Endurance, with W3 exhibiting a higher concentration level. Both genotypes displayed higher NSC under W3. Significant variations in macro and mmicro minerals were observed between water levels in both genotypes. In terms of in vitro degradability during the 24 h and 48 h incubation periods, all treatments met the acceptable level of 60-80 %. Regardless of water regimes, both Endurance and Line 2 showed nutrient concentrations meeting the minimum requirements for optimal animal production. Though, Line 2 exhibits significantly higher nutritional value and in vitro ruminal dry matter degradability than Endurance, evident in both leaves and tubers. Notably, moderate water stress conditions yielded better nutritional quality and in vitro ruminal dry matter degradability compared to both well-watered and severe water stress treatments. This suggests that applying 180-220 mm of water per season can also yield better nutritive value of these genotypes.

Keywords: Brassicas; Dairy production; Forage breeding; Irrigation; Nutrient yield; Water use.