Effects of mannan oligosaccharide on beef-cow performance and passive immunity transfer to calves

This experiment investigated the effects of feeding mannan oligosaccharide to beef cows during late gestation through 30 d of lactation on cow and calf performance and calf passive immunity. Angus and Angus × Hereford cows (n = 69; BW = 569 ± 68 kg; age = 5.3 ± 7 yr) were allotted by BW and age in a completely randomized designed. Cows were assigned to 1 of 2 treatments including 1) 1.36 kg/d during gestation of a cottonseed meal-based 30% CP supplement and 1.81 kg/d during lactation of a cottonseed meal-based 38% CP supplement (control); 2) control plus 10 g/d of Bio-Mos (Bio-Mos; Alltech Inc., Nicholasville, KY). Experimental supplementation began on February 14, 2012, and was terminated after cows consumed the lactation diet for at least 30 d. Cow and calf blood and colostrum were collected within 12 h of parturition. Cows fed Bio-Mos tended to maintain more BW from parturition through the end of the feeding period (P = 0.10). Similarly, cows consuming Bio-Mos were better able to maintain BCS from initiation of the experiment through weaning (P = 0.05). At parturition, no differences for IgG1 concentrations in colostrum (P = 0.28), cow serum (P = 0.19), or calf serum (P = 0.70) were detected. Similarly, parturition calf serum IgG2, IgA, or IgM concentrations were not different (P > 0.14). Adding Bio-Mos to winter supplement may limit BCS loss following parturition in spring-calving beef cows; however, there was no effect on passive immunity characteristics.