PSI-3 Effects of housing cow-calf pairs in drylots vs pasture during the summer on cow performance

The objective was to evaluate the effects of maintaining cows in drylots vs pasture on beef cow performance. Spring-calving, Simmental × Angus cows (n = 108; 84 ± 11 d postpartum) were stratified by age, BW, BCS, calving date, and sex of calves and allotted to 6 groups. Groups were randomly assigned to 1 of 2 treatments for 110 d: drylot (DL) or pasture (PAST). Drylot cows were limit-fed a ration consisting of corn silage, dried distillers grains, hay, corn stalks, corn, and soybean hulls to meet protein and energy requirements. Cows on pasture were rotationally grazed and offered free-choice mineral. On d 0, cows were artificially inseminated (AI). On d 0, 53, and 110 (weaning), cow BW and BCS were measured. On d 54 milk production was estimated using the weigh-suckle-weigh technique. Data were analyzed using the MIXED procedure of SAS. All binary data were analyzed using the GLIMMIX procedure of SAS. On d 0 and 53, cow BW did not differ (P ≥ 0.73) between DL and PAST. On d 110, DL cows had 74 kg greater (P < 0.01) BW than PAST cows. The BCS did not differ (P ≥ 0.66) between treatments. There was no difference in milk production (P = 0.93); however, drylot cows tended (P = 0.10) to have reduced milk fat percentage and had reduced (P < 0.01) milk urea nitrogen. There was no difference (P ≥ 0.34) in AI or overall pregnancy rates between treatments. There was no difference in foot angle or claw set (P ≥ 0.17) of cows at any time point. There was also no difference (P = 0.17) in foot treatments between DL (39%) and PAST (4%). Housing cows in drylots compared to pasture increased BW, but did not affect BCS, milk production, and pregnancy rates.