Heifer Rearing Pre Puberty

Up to 500L additional milk may be possible from a short period of  modest gain around 0.6-0.7kg LWG. from 100-200kg when
attempting to rear heifers to 600kg LWt pre calving.  This advantage is likely to be lost by the second lactation.  On farm, - given
gains ( & diets) are not extreme ( to lo - to hi ) the penalties for not achieving a modest pre - puberty gain are unlikely to have financial consequence.  Achieving a modest LWG with accuracy is impossible with  currently available ration software & demands regular weighing.  US Research may be moving closer to a stage where heifers reared to calve at 20 -210months is both practical & feasible.  In particular it may be that raising liveweight gain to 1kg Lwt per day from 0- 5 or 6 weeks on specialist milk powders may have a profoundly beneficial effect on the further development of the heifer.

Bridgets Research 82 UK heifer trial published in February 2000 by MDC showed advantages to a modest pre puberty LWG
This is in agreement with several Scandinavian, Israeli & US studies where gains below 0.8kg were achieved. pre puberty  US
Studies highlighted the need for higher protein diets at high LWG.  None of the studies were based on grass silage diets. Studies
at ARINI Ireland on grass silage diets found acceptable performance around 575KG LWt pre calving providing heifers were not excessively fat.

Take Home Messages

A low level of gain from 100-200 kg LWt of 0.63 kg LWG followed by compensatory growth for the next 100kg at 0.97
 kg gave a non significant yield increase of 456kg in the first lactation over other Low or High feed levels
It is difficult to ration within +/-0.1kg LWG without weekly  weighing at experimental units - let alone commercial farms
Experimental diets were on Hay + compound ( not the UK norm ) - poor quality silage is typical which has highly
variable intake characteristics.
Target Pre Calving weights should be 575-620 Kg at 23-24 months of age implying 0.8kg LWG throughout life

Recommendation is to
opt for a standard gain of .6-.7kg LWG from 100-200kg LWt having achieved a well grown calf of 100kg by 100 days providing
regular weighing is carried out on farm.
High Quality protein - eg Fish Meal / Soya may be desirable during the pre - puberty phase as part of a  16% CP in the total
diet. If feeding Fish 0.2kg with silage may be helpful to promote frame not fat.
From 200-300kg aim for 0.9Kg and thereafter 0.8kg LWG until 2 months pre-calving
Where there is less tight control over feeding it would be preferable to aim for a gain which does not stunt the calf.

A Calibrated Holstein Heifer Weigh Tape C15907N $2.90 is acceptable and can be purchased from NASCO
A Free Feed Calculator is available for download for rationing silage & concentrates to desired LWG
Preview the free Dairy Heifer Silage Ration Calculator here

SMALL OVER CONDITIONED HEIFERS PRE CALVING - (BCS OVER 3.5) ARE LIKELY TO SUFFER SEVERELY AT CALVING

 

  Treatment Weight Range Target Growth Actual Growth On Feed Average Growth Post Calving Wt Calving Age Yield Fat Protein Solids Mean Yield
kg LWt kg/day kg/day days kg/day kg days kg kg F&P Kg kg/day 105 days
1 Low 100-300 0.65 0.59 333 0.59 493 736 6774 260 228 488 25.2
2 High Low 100-200 0.90 0.87
200-300 0.65 0.48 316 0.59 491 728 6667 259 226 485 25.8
3 Low High 100-200 0.65 0.63                  
    200-300 0.90 0.97 281 0.73 525 724 7297 290 243 533 27.8
4 High 100-300 0.90 0.80 253 0.80 528 708 6618 257 223 480 25.2
5  Hi Lo Hi 100-150 0.90 0.87
150-250 0.65 0.61
250-300 0.90 0.93 293 0.67 501 712 6848 255 229 484 25.2
  Average       295 0.68 508 722 6841 264 230 412 25.8
  Difference       -14 0.05 17 2 456 26 13 121 2.0

Ref: H Biggadike, Bridgets Research, 02/2000, To determine the effects of different growth rates from 100-300kg LWt on
first lactation milk yields of Holstein Heifers calving at 2 years age.  Report available from MDC

Further Online Reading

1  Van.Amburgh Calf rearing at 1kg Lwt per day on a milk based 30%CP 20% Fat milk replacer
2  Van.Amburgh     Accelerated Heifer Rearing
3 Milkspecialities.com   producers of 30:20 powders used in the trials at Cornell and feeding recommendations.