Growing bred replacement heifers
Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist
Bred replacement heifers that will calve in January and February need to continue to grow and maintain body condition. Ideally, two year old heifers should be in a body condition score “6” at the time that their first calf is born. See example below of a heifer in body condition 6.
This allows them the best opportunity to provide adequate colostrum to the baby, repair the reproductive tract, return to heat cycles, rebreed on time for next year, and continue normal body growth. From now until calving time, the heifers will need to be gaining about 1 pound per head per day, assuming that they are in good body condition going into the winter months. In contrast, if heifers are allowed to lose body condition and calve in a body condition score of 4 or less (see picture below), they will produce less colostrum and their calves will have a higher likelihood of getting calf diarrhea.
Plus thin heifers may take 30 to 60 days longer to return to heat cycles. Therefore, they will calve late next year or be open (non-pregnant) at preg checking next fall.
Heifers will need supplemental protein, if the major source of forage in the diet is bermudagrass or native pasture or grass hay. If the forage source is adequate in quantity and average in quality (6 - 9% crude protein), heifers will need about 2 pounds of a high protein (38 - 44% CP) supplement each day. This will probably need to be increased with higher quality hay (such as alfalfa) or additional energy feed (20% range cubes) as wet winter weather adds additional nutrient requirements.
Wheat pasture (if adequate rainfall produces growth) can be used as a supplement for pregnant replacement heifers. Using wheat pasture judiciously makes sense for pregnant heifers for two reasons. Pregnant heifers consuming full feed of wheat pasture will gain at about 3 pounds per head per day. If they are on the wheat too long the heifers can become very fat and cause calving difficulty. Also the wheat pasture can be used for gain of stocker cattle or weaned replacement heifers more efficiently. If wheat pasture is used for bred heifers, use it judiciously as a protein supplement by allowing the heifers access to the wheat pasture on at least alternate days. Some producers report that 1 day on wheat pasture and two days on native or bermuda will work better. This encourages the heifers to go rustle in the warm season pasture for the second day, rather than just stand by the gate waiting to be turned back in to the wheat. Whatever method is used to grow the pregnant replacement heifers, plan to have them in good body condition (BCS = 6) by calving so that they will grow into fully-developed productive cows.
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