Heifers Breed Back

Beef Cattle Heifers Breed Back for second calf of heifers that are light weight at first pregnancy.
  Cattlemen for years have noted that first calf heifers tend to have lower pregnancy rates and breed back later in the breeding season following their first calf.  Much of this problem (not all) can be tied to those heifers that were younger and smaller or thinner in body condition going into their first breeding season.  Heifers that were small at the start of the breeding season often are found to be open or non-pregnant upon palpation after the breeding season is over.  However, some of the small, light, poorly developed heifers still get bred.  At first this may see to be blessing, but research data indicates that their potential for problems are not over.  Heifers that were bred when weighing only about 50% of their mature weight (instead of the target of 65% of mature weight) will be poor gambles to stay in the herd in years to come.  Data from a number of years of ago with Hereford heifers illustrates this point. 

Table 1.  The effects of weight at first breeding on reproductive performance
                                                                  Weight at start of first breeding season 
                                          Less than 550 lbs             550 - 600 lbs              More than 600 lbs 

Number of heifers 40 166 45
Pregnant 1st year 56% 77% 90%
Pregnant 2nd year of heifers calving 18% 57% 69%
Pregnant 2nd year of original heifers 8% 40% 60%
  Source:  Sprott and Troxel. Management of Replacement Heifers for a High Reproductive and Calving Rate. B-1213. Texas Agricultural Extension Service. 

     The data in table 1 above indicates two problems with heifers that are too light at first breeding.  Not many get pregnant as virgin heifers and they have a MUCH lower chance of getting pregnany while nursing their first calves.  Only 56 percent of the heifers weighing less than 550 pounds were pregnant.  In the subsequent breeding season, only 18 percent of those calving from this group were pregnant.  Only 8 percent of the lightweight heifers exposed the first year did not skip a calf.  Although some heifers will cycle and breed at very young ages and light weights, they may not have the capability to produce a calf and re breed.  Certainly heifers must attain proper growth to avoid serious calving problems.  If they do get bred, have a calf, their chances of being rebred are quite low. 

     Keeping or culling light weight pregnant heifers is a tough decision.  The data above would suggest that those that are very light are a poor risk to keep around.  If the light weight heifer is kept until calving time, the producer must make every effort to allow the heifer optimum growth without exceeding the body condition score of 6 by the time that she calves.  This should give the best opportunity to deliver a calf (probably with assistance) and to rebreed if she kept in the herd.  But remember she is still a bad bet.  Avoiding this condition while she was a young developing heifer is the best remedy! 

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