Cotton ginning was conducted at seven locations ( Figure 1 ), which are major production areas comprising eight mills ( Table 1 ), as well as at the Centre Nationale de Recherche Agronomique (CNRA) in Bouaké.

Table 1. Number of tests per mill on 170-saw gins.

The plant material used in this study was seed cotton of three varieties: CI-123, CI-128 and Gouassou Fus1, all from the Gossypium hirsutum species grown in Côte d’Ivoire. These are the varieties currently being popularized in Côte d’Ivoire. They have been selected and sold to cotton companies for cultivation.

Gins, including a 10-saw gin ( Figure 2(a) ) used for ginning seed cotton samples at research level and a 170-saw gin ( Figure 2(b) ) used for ginning seed cotton in factories. These two types of gin are the only gins involved in cotton ginning in Côte d’Ivoire. Additionally, an integrated measurement chain (CMI) type HVI was employed to determine the technological characteristics of fiber ( Figure 2(c) ). Finally, a scale type (CAMRY Price camputing scale) was used to weigh samples of seed cotton and lint ( Figure 2(d) ).

a: 170-saw gin; b: 10-saw gin; c: HVI integrated measuring chain (CMI); d: electronic scale.

The data collection process commences with a verification of the measuring instruments, followed by a cleaning of the ginning system. This is then followed by the collection of data and finally the preparation of cotton samples for processing on the 10-saw gin.

At the factory, the measuring instruments were calibrated to ensure accurate lint and seed cotton weights. This involved checking the weighing bridge and the bale weigher. It is of the utmost importance that these instruments provide accurate values during the weighing process, as any discrepancies could lead to errors in the subsequent data processing.

Prior to commencing the ginning process, a comprehensive cleaning of the machine circuit was conducted, encompassing the area where the gin cars are positioned and extending to the point where the fiber bales are formed. This process also included cleaning the saw teeth and replacing any that were no longer functional.

The data collected primarily included mass measurements for seed cotton, fiber bales, seed, and waste.

The samples taken at the mill included 5 kg of seed cotton and seed cotton free of waste taken from transport trucks and gin aprons, respectively, as well as 500 g of cotton fiber, fiber after Lint Cleaner, and from bales. The 5 kg of seed and waste-free cotton were ginned on 10-saw machines at CNRA in 1 kg batches, with three replications. The remaining 500 g samples (cotton lint, lint after Lint Cleaner, and lint on bales) were utilized as relative controls to assess the comparative agro-industrial performance of the two gin types (10-saw and 170-saw).

The parameters calculated were cotton fiber and waste rates.

The percentage of waste contained in seed cotton (%), determines the proportion of waste in relation to seed cotton. As the percentage increases, the fiber content per unit mass decreases. The percentage is calculated using the following formula:

Waste rate $\left(\text{\%}\right)=\frac{\text{Weight}\left(\text{g}\right)\text{of waste}}{\text{Weight}\left(\text{g}\right)\text{of seed cotton}}\times 100$

The percentage of cotton fiber content (%), in relation to seed cotton, determines the proportion of fiber in the overall composition. The calculation is made according to the following formula:

Fiber rate $\left(\text{\%}\right)=\frac{\text{Fiber weight}\left(\text{g}\right)}{\text{Cottonseed weight}\left(\text{g}\right)}\times 100$

Cotton samples collected in the mills and those obtained after ginning on the 10-saw gin were analyzed using an integrated HVI 1000/1000 measuring chain [7] . This fully automated device has three modules for determining technological characteristics from a 100 g sample of fiber, offering a high level of efficiency and precision. The primary technological characteristics evaluated were fiber length (UHML), fiber tenacity (Str), fiber length uniformity (UI), short fiber index (SFI), fiber elongation (Alg), and reflectance (Rd).

A Student’s T-test was used to compare the technological characteristics of gins with 10 saws (CNRA) with those of factories with 170 saws. To evaluate the effect of waste on the quality of the cotton produced by the agro-industrial process, all the aforementioned analyses were conducted using Excel 2016 and STATISTICA version 7.1 software.

The statistical analysis revealed a significant difference in fiber length for the same cotton, with a value of 29.03 mm after ginning on 10-saw gin and 27.52 mm when the cotton was processed at the factory, which uses gins with 170-saw ( Figure 3 ).

Diagrams bearing the same letter are not statistically different according to the Student-Newman-Keuls test with a threshold of 5%.

Diagrams bearing the same letter are not statistically different according to the Student-Newman-Keuls test with a threshold of 5%.

The type of gin had no impact on the micronaire index ( Figure 4 ). The micronaire index of fibers obtained after ginning on 10-saw gin (3.71) and that of fibers ginned at the mill with 170-saw gin (3.62) were found to be statistically identic.

The results for cotton fiber tenacity are presented in Figure 5 . The average fiber tenacity values obtained by using gin with 170 saws and gin with 10 saws were 27.49 g/tex and statistically identical. There was no observed variation in tenacity according to gin type.

Diagrams bearing the same letter are not statistically different according to the Student-Newman-Keuls test with a threshold of 5%.

The rate of short fibers (15.08%) at the factory ( Figure 6 ) was found to be statistically higher than that obtained after ginning on 10-saw gin (10.28%).

Diagrams bearing the same letter are not statistically different according to the Student-Newman-Keuls test with a threshold of 5%.

The average rate of uniform fibers obtained with a gin equipped with 10 saws (81.66%) was higher than that of cotton processed at the factory with 170-saw gin (78.70%).

The results of the cotton lint elongation tests are presented in Figures 7-8 . The statistical analysis demonstrated that there was no significant difference between the elongation values obtained with the 10-saw machine (6.09%) and those obtained with 170-saw machine (5.76%).

Diagrams bearing the same letter are not statistically different according to the Student-Newman-Keuls test with a threshold of 5%.

Diagrams bearing the same letter are not statistically different according to the Student-Newman-Keuls test with a threshold of 5%.

UHML: Cotton fiber length; Mic: Cotton fiber micronaire index; UI: Cotton fiber length uniformity; SF: Short fiber rate; Str: Cotton fiber tenacity; Alg: Cotton fiber elongation; Rd: Reflectance.

The deviations between the technological characteristics of cotton ginned on a 170-saw gin and a 10-saw gin and the tolerable deviations are given in Table 2 . The differences between the characteristics of fibers from the two types of gins are 1.51 mm for length, 0.09 for micronaire index, 2.96% for uniformity, 4.79% for short fiber content, 0.87 g/tex for tenacity, 0.31% for elongation, and 0.19 for brightness. In accordance with the tolerable values, the differences obtained in length (1.51 mm), length uniformity (2.96%) and short fiber content (4.79%) are out of the norm.