Estimated reading time: 8 minutes
- Wet chemistry analysis is the first point of reference and the most accurate indication of nutritional value.
- The second method involves near-infrared reflectance spectroscopy (NIRS).
- Each grade of lucerne hay has a specific application, and its value ultimately depends on the livestock producer’s objectives.
- The quality of lucerne hay is influenced by multiple factors, spanning from the cultivation of the crop (up to cutting) to the completion of the haymaking process.
- Seasonal fluctuations in lucerne hay quality are expected, given the strong influence of weather conditions on yield and nutritive value.
In the January issue of Stockfarm, part one of this series explored the role of lucerne hay in South Africa’s animal feed industry. This second instalment focusses on lucerne grading and the quality of the crop in South Africa.
SA’s lucerne grading system
The quality or nutritional value of lucerne hay can be assessed using several methods. The first is wet chemistry, in which each indicator is chemically measured through specific laboratory procedures. Wet chemistry analysis is the first point of reference and the most accurate indication of nutritional value. However, it is costly, complex, and time-consuming.
The second method involves near-infrared reflectance spectroscopy (NIRS). It is quicker, less costly, and less complicated than conventional procedures. However, the accuracy of the prediction of nutritional value will largely depend on the accuracy of the calibration used on NIRS (Scholtz 2008; Scholtz, Van der Merwe, and Tylutki, 2009a). Finaly, nutrition estimation tables can also be used. Each of these methods has its benefits and drawbacks.
Evaluating the comparative nutritional value of forages has been a long-standing focus in forage quality research. Over the years, multiple mathematical models have been developed, including relative feed value (RFV), total forage index (TFI), adjusted total forage index (ATFI), and relative forage quality (RFQ) (Scholtz, 2006). These models primarily assess differences among forages based on maximal dry matter intake (DMI) and digestibility. Notably, these models exclusively consider the forage’s chemical composition while ignoring physical characteristics, animal factors, and associative effects.
Advances in quality assessment
Existing models in the literature typically rely on the potential for digestible energy intake to indicate forage quality. Scholtz, Van der Merwe, and Tylutki’s (2009b) research demonstrated substantial variations in the energy and protein composition and availability thereof in South African lucerne hay. Among these, acid detergent fibre (ADF) emerged as the single best predictor of milk yield in dairy cattle, surpassing all other indicators.
Scholtz, Van der Merwe, and Tylutki developed a grading quality index known as the New Lucerne Hay Quality Index (NLQI) that uses ADF, ash and lignin to predict milk yield in dairy cattle. This index is a grading system for South African lucerne hay in commercial applications. Notably, this methodology employs NIRS to predict lucerne hay quality. It is a rapid and accurate evaluation system currently used to grade lucerne hay in South Africa.
Before 2008, lucerne hay quality in South Africa was assessed subjectively, based on colour, odour, and foreign material, with only minimal attention to crude protein and fibre due to the expense and complexity of wet chemistry analysis. Nutritional quality was often estimated based on published tables, which could lead to over- or underestimation (Van der Merwe 1970; Erasmus et al., 1990; Scholtz, 2008). The NLQI provides a universal measure of lucerne hay quality, based on production potential and digestible energy content for dairy cattle. Table 1 outlines the official lucerne hay grading standard currently implemented in South Africa.
Table 1: Quality grades of the South African lucerne hay grading system.
| NLT grade | NLQI | Foreign materials |
| Supreme | 108 and higher | Absent |
| Prime | 104 to 107 | Absent |
| Grade 1 | 100 to 103 | Absent |
| Grade 2 | 95 to 99 | Present |
| Grade 3 | 94 and less | Present |
Practical implications of grades
Each grade of lucerne hay has a specific application, and its value ultimately depends on the livestock producer’s objectives:
- Grade 1: Offers a balanced combination of effective fibre and available energy; this makes grade 1 lucerne suitable as the sole roughage source for sheep and cattle.
- Supreme and prime grades: Highly digestible but low in effective fibre, these should be mixed with lower-quality roughage to maintain rumen health.
- Grade 2 and 3: Lower digestibility makes these grades excellent sources of effective fibre but less suitable for energy and protein needs.
Lucerne hay remains one of the most versatile, palatable, and sought-after crops for livestock producers.
Factors affecting quality
The quality of lucerne hay is influenced by multiple factors, spanning from the cultivation of the crop (up to cutting) to the completion of the haymaking process. Producers must understand and manage these factors to maximise productivity and achieve consistently high-quality lucerne. Seasonal variations, such as changes in temperature, solar radiation, and day length, significantly affect lucerne growth and hay production. Among these, temperature is particularly important, with the quality of lucerne deteriorating more swiftly in warmer locations (Orloff, 2007). Conversely, warm temperatures will accelerate plants’ maturation and lignification processes, reducing lucerne quality but increasing overall yield (Summers and Putnam 2007).
Weather conditions have a greater impact on lucerne hay production than soil conditions (Putnam, Summers and Orloff, 2007). However, poor soil conditions can hinder root development, limiting nutrient and water uptake, which in turn affects hay quality (Solontsi et al., 2022). While lucerne can grow in a variety of soils, sandy loam, silt loam, and clay loam are generally preferred (Summers and Putnam, 2008).
Lucerne production is highly susceptible to high soluble salt content in the soil. High salt levels will affect the growth and development of lucerne stands (Lu et al., 2021). Younger lucerne stands will yield significantly higher quality and yield than lucerne with older stands (Undersander et al., 2021). While soil conditions are crucial for forming healthy lucerne stands, the soil type significantly influences the quality and yield of lucerne hay (Solontsi et al., 2022).
In South Africa, lucerne is cultivated across diverse climate zones and farming regions, resulting in variability in soil nutrient levels. Optimal nutrient availability allows lucerne to compete effectively with weeds and maintain hay quality (National Lucerne Trust, 2023). Fertilisation is therefore essential for improving soil conditions, supporting the establishment of good stands, increasing yield and quality, and enhancing the longevity of lucerne crops (Meyer et al., 2007; Undersander et al., 2021).
Haymaking is the most critical factor in preserving the quality of lucerne hay, regardless of production practices or environmental conditions. Poor haymaking practices can result in quality losses of up to 70%. Several key operations influence lucerne hay quality and profitability, including cutting, curing, raking, baling, and storage (Rotz and Shinners, 2007; Summers and Putnam, 2008). Hay quality is also strongly affected by weather conditions during cutting and drying, as well as moisture levels during raking and baling (Mueller and Orloff, 1994). When determining cutting schedules, producers must consider market conditions, plant physiology, seasonal factors, and prevailing weather conditions (Orloff and Putnam, 2006).
The quality of lucerne hay largely depends on the proportion of leaves retained in the bales, as leaves constitute the most valuable component of the final product. Management practices that promote leaf loss during harvest and handling can substantially reduce overall hay quality. In addition, baling hay at high moisture contents (20% or greater) increases microbial activity, leading to mould development and overheating, which further degrades hay quality (Rotz and Shinners, 2007; Martinson, Coblentz, and Sheaffer, 2011).
SA-produced lucerne hay
Seasonal fluctuations in lucerne hay quality are expected, given the strong influence of weather conditions on yield and nutritive value. More moderate climate conditions typically occur at the beginning and end of the production season, when daytime temperatures range between 22 and 24°C and do not drop in the traditional rainfall months in the summer rainfall areas (Putnam, Summers, and Orloff, 2007).
Variations in quality are illustrated in Figure 1. Superior quality lucerne hay is generally produced in August to September, marking the start of the production season, and again towards the end of the season in March to May. Data in Figure 1 are averages of analysis done over several years on all grading instruments across all production areas. Acquiring lucerne hay of superior quality in these months is common, with an analytical index grade exceeding 108 on the NLQI grading scale.
Figure 1: Seasonal quality variation of South African lucerne hay. (Source: NLT, 2023; own calculations)
Figure 2: Quality variation of South African lucerne hay. (Source: own calculations, 2023)
The quality distribution of South African lucerne hay is presented in Figure 2. The majority of annual production falls within grade 1 (38,38%), followed by prime grade (25,7%). Supreme grade lucerne hay is produced only during relatively short windows at the beginning and end of the production season. Lower quality grades are typically associated with unfavourable weather conditions during the production season, as well as challenges related to haymaking practices. – Dr Hermias van Niekerk, Department of Agricultural Economics, University of the Free State
The third instalment in this series in the next issue of Stockfarm will focus on lucerne hay production in South Africa. For more information or references, send an email to vNiekerkHN@ufs.ac.za or visit the National Lucerne Trust website at www.lusern.org
