Influence of Nutrient Supplementation on Body Weight and Condition and Pregnancy of Market Beef Cows Grazing Stockpiled and Spring-Growth Tall Fescue1

Seventy-five crossbred, non-pregnant beef cows [age = 4.5 ± 0.2 yr; BW = 395 ± 10 kg; body condition score (BCS) = 4.3 ± 0.2] were purchased from local auctions during 2 yr to determine the effects of supplementation on BW, BCS, ADG, pregnancy rate, and net income of market cows grazing stockpiled and spring-growth, endophyte-infected tall fescue (Festuca arundinacea Schreb.). Cows were assigned to one of six pastures (two pastures per treatment each year) of tall fescue for 160 d (yr 1) or 147 d (yr 2) and one of three supplementation treatments: 1) soybean hulls (SH), 2) corn:soybean meal (CSB), or 3) not supplemented (control). Supplements were fed at 0.91 kg/d per cow. Cows were sold at a local auction at the termination of the experiment. Forage availability was not affected (P>0.10) by supplementation and averaged 3637 ± 239 kg DM/ha throughout the grazing period. Supplementation did not influence (P> 0.10) ADG; overall, cows gained 0.47 ± 0.14 kg/d. Cows supplemented with SH (493 ± 25 kg) or CSB (485 ± 25 kg) had heavier (P<0.05) selling BW than control cows (462 ± 25 kg). Pregnancy rate tended (P=0.10) to be increased for cows receiving CSB (96%) compared with control cows (74%). Selling price of pregnant cows was increased (P<0.05) compared with non-pregnant cows. Supplementation of market cows increased selling BW but did not affect net income. Pregnancy rate tended to be increased in CSB cows, and selling price of pregnant market cows was greater than non-pregnant cows.