Keep replacement heifers growing

March 22, 2009 07:00 PM
 

Glenn Selk

Replacement heifers that have just reached puberty and started cycling may be vulnerable to any drastic change in feed intake.

A small trial conducted at Oklahoma State University illustrates the impact that sudden severe reduction in energy intake can have on cycling activity in replacement heifers. Nineteen heifers were divided into two groups. Both groups were fed at 120% of the maintenance requirements needed for yearling heifers. By the use of hormone assay and ultrasonography, it was determined that all heifers were cycling when the treatments began.

Nine of the heifers were continued on the 1.2 X maintenance diet. The other ten heifers were placed on a diet that was 40% of the requirement for maintenance. They remained on this diet for 14 days. At the conclusion of the 14 day treatment period, only 3 of the feed restricted heifers were still cycling, whereas all of the heifers receiving the 1.2 X maintenance were still cycling.  

Impact of sudden, severe reduction in feed intake on cycling activity of yearling heifers

 

Treatments

 

1.2 X Maintenance

0.4 X Maintenance

Day of treatment

Day 0

Day 14

Day 0

Day 14

# of Heifers

9

9

10

10

Weight

704

711

691

658

# cycling

9

9

10

3

This small, but impressive, data set illustrates clearly that we must be cautious about any disruption in the feed intake of replacement heifers at the start of their breeding season. Movement from high quality cool season grass (in the spring) to dormant winter native range may cause such a weight loss in a short period of time.

Making changes in supplement programs at the start of the breeding season should be done carefully and gradually to avoid any chance of digestive disorder and the possibility of the heifers going "off-feed". 


Glenn Selk is Extension Cattle Reproduction Specialist at Oklahoma State University.
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