Effects of whole cottonseed supplementation on performance, semen quality, and manganese superoxide dismutase concentrations in blood and semen of beef bulls

Abstract

This research aimed to determine the effects of whole cottonseed on performance, semen quality, and manganese superoxide dismutase (MnSOD) concentrations in the blood and semen of beef bulls. In a completely randomized design, 46 (BW = 457 ± 12 kg; 16–18 mo old) Angus bulls were stratified by BW and randomly assigned to 1 of 3 treatments: DD (n = 14, control; 3.18 kg/d dried distillers grain), WD [n = 16; 1.59 kg/d whole cottonseed (0.56 and 0.82% free gossypol in yr 1 and 2, respectively) and 1.59 kg/d dried distillers grain], or WW (n = 16; 3.18 kg/d whole cottonseed). Bulls were weighed and blood and semen were sampled on d 0, 30, and 60. Body weights and morphological characteristics of spermatozoa were measured in both years, and MnSOD concentrations of blood and semen were measured in yr 1. There was a treatment effect for ADG (P = 0.002) as bulls fed WW had a decreased (P < 0.03) ADG compared with bulls fed WD and DD. A time effect was observed for scrotal circumference (P < 0.001). Scrotal circumference measurements increased on d 60 compared with d 0 and 28 (P ≤ 0.02). There was no time main effect for percentage of spermatozoa with other abnormalities (P = 0.87); however, there was a treatment effect (P = 0.04). Bulls in the WW treatment had fewer other abnormalities than bulls in DD (P = 0.01) but were not different than WD (P = 0.27). Whole cottonseed did not affect reproductive parameters measured in this study or blood and semen concentrations of MnSOD. According to these results, WCS supplemented to beef bulls at 0.7% of BW for 60 d may not negatively affect semen quality or MnSOD concentrations in the blood or semen.