background image
21
Forage & Nutrition
Guide 2018
Maintaining energy levels at
grass to optimise fertility
Potential fertility issues need to be addressed this spring, otherwise dairy
producers will start to rack up additional herd costs
Trial findings, coupled with first-hand experience from New
Zealand dairy farmers, confirm that introducing rumen-
protected fat to the diet improves body condition and can
deliver a return on investment in terms of fertility alone.
There's every temptation to make big cost savings and cut out
purchased feed as soon as the cows have been turned out.
However, spring is a key time when producers need continued
attention to detail. That includes maintaining energy levels
in the diet to complement high protein grass, otherwise cows
will start to milk off their backs (maintain milk production at
the cost of body condition) and, consequently, suffer fertility
issues which pose an underlying and very real cost to the
herd.
Cows losing body condition make a significant contribution
to the national herd's poor conception to first service rate.
Data from Kingshay Health Manager herds in Britain report a
conception to first service rate of 36 per cent and an average
calving interval of 410 days (Dairy Costings Focus, 2015), with
each day's extended calving interval costing £4.13 (4.70).
So, pregnant cows are far more valuable than empty cows.
FEEDING
Feeding a balanced diet including energy from a rumen-
protected fat is an investment which will certainly pay
dividends now and for the medium to long-term. Feeding
rumen-protected fat in spring as a concentrated source of
energy results in improved body condition according to trial
findings within the Myerscough College herd in Lancashire.
Freshly calved cows from the college's 8,300L rolling
average herd were offered a total mixed ration (TMR) diet
plus concentrate containing Megalac rumen-protected fat
at either two per cent or six per cent inclusion rates. Cows
continued on these diets for a total of 16 weeks, but were
turned out to grass from week 12 for the final four weeks of
the study.
Body condition score was similar between the two groups until
turnout, at which stage the cows that were fed the higher rate
of rumen-protected fat received sufficient energy to maintain
body condition at a time when spring grass contains relatively
high levels of protein. These cows remained in target condition
score of just under 3, while those offered the control diet lost
significant condition.
TESTIMONIAL: NEW ZEALAND FARM
Adding a rumen-protected fat is a key part of the diet for Roger Blunt who farms 500 Holstein Friesian cows
inHamilton,NewZealand.Averaging8,000L,theKarapiroFarmplacesstrongemphasisonproductionfrom
grass,howeveritmaintainssupplementaryfeedingtofillthegapthatgrassalonecan'tfill.Supplementsare
offeredasabufferfeedtwicedailyasamixofmaizesilage,palmkernelandrumen-protectedfat.
"Ourbusinessistotallyprofit-driven.Wehavehadtothinkreallyhardaboutourcostsofproduction,and
re-adjustaccordingly,particularlywhenmilkpricesreflectglobalmarketplacetrendsandslumps,"Roger
explains.
"However,weneverlosesightofgrass,andhavingtheknowledgeofhowtousesupplementsmakesthe
difference­wedon'tbelievethatrelying100percentongrassforproductionisthewaytogo.Wehave
usedMegalacrumen-protectedfatforthreeseasonsandcanseethecostbenefitsthroughtheextraenergy
supply and the maintenance of condition through the milking season.
"Withfertility,we'veseenanimprovementinconceptionratefrom62percenttoapproximately75
percent,whileemptyratehasreducedfrom15percenttoninepercent.Theherdhasa12-week
matingperiodandcalvesoverastrict84days."
Theover-ridingbenefit,Rogeradds,istheloweremptycowrateallowingfewerculls,aswell
as retaining a tight calving pattern and greater focus on animal productivity for selection
and replacement.
* Megalac is a Volac product.
Author: Neil Birkett
Volac
A