It’s June and this means your heifers are home. Unfortunately, many of you are reporting that your heifers have arrived home well underweight, largely due to the drought over summer.

For many heifers there is a large gap to close in a short period of time. Remember that the target is for a heifer at calving to be at 90% of her mature liveweight. To put this in numbers: if a heifer is expected to have a mature weight of 500kg, she needs to be 450kg when she calves for the first time. If she is only 360kg now, she needs to gain a whopping 90kg between now and her calving date, bearing in mind that it is almost impossible for her to gain any real weight in the last month pre-calving because they can’t physically eat enough due to the space & energy taken up by the growing foetus.

What do I do if heifers end up reaching calving behind target? 

Calving down underweight heifers impacts on milk production for their first lactation as well as in calf rates. To mitigate these impacts, we need to take the pressure off these girls around calving. Options to help include:

• Weigh heifers now and ensure those behind target (or the whole mob)  are on a weight gain ration of good feed quality.  This means for heifers, targeting a mature liveweight of 500kg, need 12kgDM offered per day (eating 10kgDM a day). 
• Weigh heifers again around calving time so you know who has reached target and who has not. Consider using once a day (OAD) milking, either for the whole season or for a few weeks at the start of the season.  If you choose OAD for some animals all season their overall production will be lower but in calf rates are considerably better so longevity in the herd is improved. It is expensive to get a heifer to her first lactation for her to then leave the herd after only one season. OAD milking reduces energy outputs meaning heifers can partition more energy for growth and cycling. Maximum benefit of AOD milking is seen when animals are not walking to the shed twice a day. 
• Mix your heifers with cows prior to the start of calving.  This has been proven to impact heifers less compared to introducing them at calving time. Putting heifers in a separate mob with some mature cows while ensuring the majority of the mob are heifers allows them to integrate well, learning to socialize and compete for feed more successfully. 
• Optimise transition.  Downer risk is lower in young cows however adequate magnesium is important for condition gain. Magnesium should be going into the system in June via the water, feed or dusting. Low magnesium occurs with lush rapidly growing grass and affects the rumen microbe function and animals’ ability to gain condition. 
• Reducing BCS loss post calving.  Ensure the diet offered is providing enough energy and heifers are in a mob that reduces competition from older cows as much as possible. Acclimatize heifers to the feed pad prior to reduce risk of lameness from the increased time standing on concrete after calving. 
• Be vigilant  around calving time checking heifers aren’t having calving trouble and if so that they are assisted in a timely manner. 
• Metricheck heifers early  to help identify and treat endometritis and get heifers cycling and in calf earlier. 
• Remember heifers are still growing after their first calving so checking that their mineral status is adequate is really important.  It’s not too late to check this now! Copper and selenium both impact reproductive performance. This is even more important if the mineral status at grazing before heifers come home is unknown. 

If you are worried about what to do with heifers that are behind and how to optimize their longevity in the herd don’t hesitate to contact us at Anexa.

*Photo caption: This heifer mob arrived home around May 1st and weighed 364kg on average. They need to gain 87kg to get to their calving weight target by the 13th June.