Proper pre – breeding heifer development and management will improve lifetime cow productivity 

Yearling heifers that conceive early in their first breeding season will have increased lifetime production and efficiency resulting in more profit potential.  Proper management and development prior to the breeding season is key to increasing the likelihood that they will conceive early in their first breeding season.  Manipulation of key factors in the onset of puberty, which we will discuss, can positively influence cyclicity prior to the breeding season leading to improved heifer conception early in their first breeding season.

First, the heifer needs to be old enough and heavy enough prior to the breeding season to have estrous cyclicity.  The age part is dependent on breed.  British and continental breed cattle should have estrous cyclicity such that they have their first calf at approximately 2 years of age.  However, Brahman influenced cattle may have delayed estrous cyclicity resulting in having their first calves at approximately 2.5 to 3 years of age.  Cattle producers and researchers have observed a high percentage of heifers cycling at 65% of their mature weight, which should be your target body weight prior to the breeding season.  Based on the target heifers from 1200 – pound mother will need to weigh 780 lbs. prior to the breeding season.

Confirmation of estrous cyclicity is needed prior to the breeding season, which is done through a pelvic exam.  A veterinarian does the exam approximately 30 to 60 days prior to the breeding season and it determines if the reproductive tract is sound in function and ready to conceive a calf.  The scoring system is 1 to 5 with one being immature or non – cycling and five being cycling with a palatable corpus luteum.  Heifers that score a three are on the verge of cycling while heifers that score a four are presumed to be cycling.  Based on this knowledge if you have heifers that score one or two they are probably heifers that need to be culled while three, four or five heifers would be good candidates to enter the breeding season.

Another useful and important piece of information that we receive from pelvic exams is pelvic area.  During the exam, the heifers should measure a pelvic area of at least 150 cm2, which is calculated by multiplying the width and height of the pelvis measured through palpation with a pelvimeter.  If heifers have a pelvic area less than 150 cm2 then they will be less likely to have a calf with ease and therefore should be consider to be culled.

Quality of nutrition plays a role in whether the heifer reaches her weight target or not.  You need to know the weight at weaning and compare that to the target breeding weight and determine the number days to breeding to identify how much daily gain those heifers need to reach their target weight.  Once you have determined the gain needed to meet that requirement then determine a nutrition program to meet that gain.  In addition, you want to watch body condition score and make sure the heifers are not getting to fat and manage the heifers to a body condition score of six prior to the breeding season.  A body condition score of six is characterizes as:

  • good smooth appearance throughout
  • some fat over tail head and in the brisket
  • rounded back and can palpate fat over the ribs

If heifers get to fat during the development process, they may have reduced milking ability as cows. Moreover, if you are supplementing them and they are too fat it is a waste of money.  In addition, one additive that you might incorporate into the heifer diet is an ionophore, which are commonly known as Rumensin and Bovatec.  Heifer daily ionophore consumption of 200 milligrams per head per day can hasten the onset of puberty and improve daily gain by 0.1 to 0.2 lbs.  These results are beneficial in getting heifers ready for the breeding season.  If you plan to use an ionophore, make sure that you follow the label instructions when feeding it to the heifers daily.

One final thing that influences the onset of puberty in replacement heifers is the environment they are managed in prior to the breeding season.  The portion of the environment that is manageable by cattle producers is feeding management and the health status of the heifer.  Replacement heifers need to be feed and managed separately from the rest of the cowherd because they have higher nutritional demands.  Furthermore, visit with a veterinarian and make sure that your heifers are up to date on all immunizations as well as dewormed regularly.  By controlling this portion of the environment, your heifers will be healthier, consume the proper nutrition that is needed and be more likely to meet pre – breeding targets for cycling prior to the breeding season.         

Source: Patrick Davis, Livestock Specialist