Evaluation of whole cottonseed consumption on growth and reproductive function in male cervids

Abstract

Twenty-four fallow bucks were randomly allotted by body weight, body condition score and age to one of two treatment groups: control (C; 4:1 corn:soybean meal) and whole cottonseed (WCS; 1.14% free gossypol), to evaluate effects on body weight, body condition score, antler development and testicular function. Rations were calculated to be isocaloric and isonitrogenous. Bucks were fed daily as much whole cottonseed as they would consume. The amount of WCS refused was recorded. Consumption of WCS reached 0.91 kg/head/day for older (2yr) and 0.68 kg/head/day for younger (1yr) bucks. Bucks were maintained on 1/4 acre ryegrass/coastal bermudagrass pasture with free access to minerals, salt and water. Alfalfa pellets were supplied at 0.45 kg/head/day and increased when forage was limiting to maintain rumen function. Body weight (BW), body condition scores (BCS), antler measurements, testicular measurements and jugular blood samples were collected at 28-day intervals from 5/18/00 to 7/13/00 and 14-day intervals from 7/27/00 to 11/2/00. Plasma was assayed for testosterone via radioimmunoassay (RIA). Ejaculates were collected via electroejaculation at 14-day intervals beginning on 7/27/00 when the bucks had reached hard antler. Control bucks had greater (P< 0.08) BW and greater (P< 0.0005) BCS than WCS bucks. WCS bucks had lower total antler weight (161.21 ± 32.54 g; P< 0.002) and smaller average antler length (22.20 ± 3.58 cm; P< 0.02) than controls (336.38 ± 32.54 g; 36.0 ± 3.58 cm ). Antler density of WCS (5.04 ± 0.83 g/cm) was less (P< 0.07) than control bucks (7.37 ± 0.83 g/cm). Paired testis volume (PTV) was not different (P> 0.1) between treatments but date of maximum PTV was earlier (P< 0.04) for WCS (Julian day 242 ± 3) compared to control bucks (Julian day 250 ± 3). Maximum concentration of plasma testosterone was lower (P< 0.003) for WCS (0.79 ± 0.14 ng/ml) than for control bucks (1.49 ± 0.14 ng/ml). Maximum plasma testosterone was reached earlier (P< 0.04) by WCS buck (Julian day 223 ± 6) than by controls (Julian day 242 ± 6). Consumption of WCS suppressed weight gain, body condition scores, antlerogenesis and altered testis function in fallow bucks.