Feed conversions of calves fed creep feeds have been quite variable to say the least. Conversions of 5:1 or 5 pounds of grain consumed to 1 extra pound of calf weight are very rare and the optimum that can be expected when producers are using a "typical" high energy creep feed. Conversions may get as poor as 15:1 in some situations. Therefore it is obvious that several factors come in to play to determine the amount of creep feed that is consumed for each additional pound of gain.
Cows that give large amounts of milk to their calves will provide enough protein and energy to meet the growth potential of their calves. In that scenario, it is reasonable to assume that the feed conversion from creep feeding could be quite poor (10:1 or worse). If however the milk production of the cows is limited for any reason, then the added energy and protein from the creep feed provides needed nutrients to allow calves to reach closer to their genetic maximum capability for growth. Calves from poor milking cows may convert the creep feed at a rate of about 7 pounds of feed for each pound of additional calf weight. Poor milking can be a result of genetically low milk production or restricted nutritional status. Nutritional restriction due to drought situations often adversely affects milk production and therefore calf weaning weights. Shortened hay supplies and reduced standing forage due to drought or severe winter weather often set the stage for the best results from creep feeding.
These feed conversion ratios become important when making the decision to buy and put out creep feed for spring born calves. One review of data on creep feeding concluded that an average estimate of feed to gain ratio would be 9 pounds of feed to each 1 pound of added gain. As you are calculating the cost of creep feeds, remember to include the depreciation cost of the feeders and the delivery of the feed. Then of course, it is important to compare that cost of creep feeding to the realistic “value of added gain”. Estimates for the value of each pound of added gain next fall will be near $1.00. Therefore the cost of the creep feed consumed must be less than the $1.00 estimated value of each pound gained.
Different ranching operations will come to different conclusions about the value of creep feeding. In fact, different conclusions may apply to different groups of cows within the same herd. Creep feeding may be more beneficial to calves from thin, young cows and less efficient to calves reared by mature cows that are in better body condition and producing more milk.
Source: Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist