In-vitro digestibility and energy utilization of extruded cotton gin trash by ruminants



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Texas Tech University


One metabolism study and two In vitro experiments were utilized to detenmine the effects of extruded gin trash (EGT) with added starch on in vitro dry matter digestibility (IVDMD), apparent dry matter digestibility (ADD), feed intake (Ft), nitrogen balance (NB), and nitrogen retention as a percentage of intake (NRI) and absorption (NRa). The cotton gin trash (CGT) used in these experiments was extruded at the Agricultural Research Service (ARS) Cotton Production and Processing Unit (CPPRU) in Lubbock, Texas. An Insta-Pro model 2000 Extruder (Triple "F", Inc, Des Moines, Iowa 50322) was utilized to process the experimental material at 88 to 104°C, and a solution of 88 to 91 °C non-food grade cornstarch was injected onto the CGT at the pre-determined levels just prior to cooking. Roughage treatments analyzed during the in vitro experiment included cottonseed hutis (CSH), ground gin trash (GGT), and extruded gin trash (EGT) with varying levels of added starch. The first in vitro experiment showed a quadratic effect of starch level on IVDMD, and greatest digestibility was achieved with 13% added starch. Both in vitro experiments showed overall that, regardless of processing, cotton gin trash treatments were more digestible (P < .01) than cottonseed hulls. Processing by extrusion atone did not significantly enhance the digestibility of cotton gin trash, but did improve the rate of its digestibility. Extrusion with added starch did result in enhanced (P < .05) digestibility when compared to the other treatments. Concentrate diets containing a 30% roughage portion of CSH, GGT, or extruded gin trash with 4 (EGT 4) or 13% (EGT 13) added starch were additionally analyzed by In vitro analyses and used for a metabolism study. Digestibility values obtained in the metabolism study were approximately 6 to 10% higher than those obtained during in vitro analysis, and results showed EGT treatments more digestible than GGT and CSH. Ground gin trash and EGT 4 showed more acceptable NB, NRi, and NRa. However, EGT 4 and EGT 13 did not differ from CSH in the case of NRi and NRa. Of alt variables measured, CSH treatment diets were superior only for Fl. Data obtained from all experiments of this study prove EGT with less than 13% added starch to be a viable roughage alternative for ruminant animals. However, GGT and EGT 4 performed the best in terms of overall feeding value when all measured variables were accounted for simultaneously.



Cottonseed products as feed, Fiber in animal nutrition, Ruminants, Agricultural wastes as feed