A study was conducted in 2012 to evaluate DMI and feed efficiency during a 70 day feeding period in beef cows based on cow size. This study was conducted in a group of 38 Angus cross beef cows during their lactating (with heifer calves at side) and non-lactating period, following weaning. Based on initial BW at the beginning of the feeding period, cows were sorted into a light or heavy BW group for comparison. During the lactation feeding period, cows in the heavy BW group weighed on average 126 lbs more in BW and consumed 2.9 lbs more ryegrass baleage and hay compared to cows in the light BW group (Table 1; Walker et al., 2013). The differences observed between the light and heavy BW group cows were similar to what was observed during the non-lactating feeding period where cows in the heavy BW group weighed 143 lbs more and consumed 2.8 lbs more ryegrass hay compared to cows in the light BW group. Based on the difference in DMI observed in this study, if the difference in BW between the two groups of cows was 200 lbs, DMI would increase 4.05 lbs for every 200 pound increase in cow BW. If you look at feed to gain ratio for the two BW groups, cows in the heavy BW group had a lower feed to gain ratio during lactation. This could have explained why intake increased at a greater level for the heavy BW cows than what the NRC (1996) tells us, and milk production could have been higher for the cows in the light BW group. However, feed to gain ratio during the non-lactating period was higher for cows in the heavy BW group. This tells us that DMI requirement for cows of bigger body size during the non-lactating period may be greater than the NRC predicts