Ruminal Fiber Value of Cotton Linters and Effect on Digestibility and Feedlot Performance by Lambs

Abstract

Two experiments, with growing sheep, were conducted to determine the effects of feeding cotton linters (CL) on digestibility and feedlot performance and hematological, pathological and histopathological variables. Experiment 1. Five growing lambs were used in a digestibility and nitrogen (N) balance study. Treatments consisted of control (basal diet) with 25% cottonseed hulls (CSH) and four diets composed of 60% control plus 40% roughage. The 40% roughage of the four diets consisted of CSH or three different mixtures of CL and CSH in the ratios of 1 part CL plus 5 parts CSH (1 + 5 mix), 2 parts CL + 5 parts CSH (2 + 5 mix) and 3 parts CL + 5 parts CSH (3 + 5 mix). Lambs consuming 1 + 5 mix, 2 + 5 mix, 3 + 5 mix or CSH alone exhibited similar N retention, percent N intake retained, dry matter digestibility (DMD) and organic matter digestibility (OMD). Lambs fed the control diet, as would be expected, resulted in greater (P < .01) values for the four variables studied than lambs on other treatments. Experiment 2. Seventy-two growing-finishing lambs were provided a sorghum based supplement (.75 kg. daily) plus roughage ad libitum to determine the effect on intake, gains and feed efficiency. Roughage sources were: A) corn silage; B) CSH; C) 1 + 5 mix and D) 2 + 5 mix. Lambs consuming the CL + CSH mixtures demonstrated average daily gains (ADG) and feed efficiency (FIG) similar to those consuming corn silage or CSH. However, lambs on corn silage had lower (P < .05) average daily feed (ADF) consumptions than any of the other treatments. Similar ADF values were observed for lambs on the CSH and 1 + 5 mix treatments. However, lower (P < .05) ADF consumption was observed for the 2 + 5 mix compared to the CSH group but similar to the 1 + 5 mix. Blood samples were taken from five randomly selected lambs on each treatment. Analysis showed no treatment differences for hemoglobin (Hb), percent packed cell volume (PCV), red blood cells (RBC), total leucocytes (WBC), differential leucocytes, plasma alkaline phosphatase (PAP) or plasma glutamic oxaloacetic transaminase (GOT). These data would tend to suggest that CL can be used as a partial substitute of the roughage (CSH) without affecting any of the variables evaluated in these experiments.