Page 117 - NZ Herefords Magazine 2019 Edition

INCREASED COW BODY CONDITION SCORE INCREASES REDUCED DAYS TO CALVING EBV MEANS COWS GET IN
PROBABILITY OF PREGNANCY. B+LNZ GENETICS BEEF CALF EARLIER. B+LNZ GENETICS BEEF PROGENY TEST
PROGENY TEST
50 slope = 0.502
1.0
Group 40
0.9 Caberfiedh
Probability of pregnancy 0.8 Year Conception Rate 30 Actual
Mendip Hills
Rangitaiki
Tautane
Expected
Whangara
0.7
20

2016
0.6 2015
2017 10 Sire days to
-8 -4 0 calving EBV
0.5
4 5 6 7 8 9
BCS The days-to-calving EBVs were the tools designed to
address fertility, he said.
Body Condition Score (BCS) at mating is another “Essentially, it’s the number of days between the bull going
management tool and Archer said the Beef Progeny Test data out and the cow calving. In essence, we’re talking about how
on commercial farms showed most heifers were in good nick, many cows get in calf in the first cycle, versus the second cycle,
with a BCS of 7 to 7.5 or more. The progeny test had shown a versus the third cycle (if your bull is still out).
relation between BCS and conception rate. “We want to get a negative number, so -5 is better than -4
“Below BCS 6 the fertility of the cows drops off markedly. for example. She’s getting in calf quicker, there’s fewer days
At 6 to 7.5 you are still getting a response. After that, putting between the bull going out and the average cow calving.”
any more fat on the animal you are not helping her much at all. Scrotal size, and the physical look of the bull in this
Seven or better is quite adequate for good fertility outcomes.” department, was also a consideration, but Archer believed this
EBV was more a tool for bull breeders than commercial farmers.
LOOKING AT GENETICS “Scrotal size is important because you’ve got to have bulls
In terms of EBVs when selecting a sire, the first one to look with enough serving capacity, but that should be an issue for
at is days to calving, though other traits like scrotal size and rib breeders of the bulls. I would focus on the days-to-calving EBV.”
fat are worth considering. Overall, Archer said the proof was in the pudding in terms of
Archer explained fat and fertility were two slightly different things. how long a cow stayed in the herd.
“There’s no doubt rib fat is an important EBV, but you’ve got “The reason most cows leave the herd is because they
to remember that it was originally designed as a carcass EBV have failed to get back in calf. Longevity and cost of rearing a
tool…My personal belief is when you’re having trouble getting replacement; a lot of that is about fertility, and it’s something we
cows to a BCS of 6 to 7, that’s when you want to put a bit more need to keep focusing on.”
fat into the animals.
“Fatness is about how easily we can get our cows into good
condition, in order to get those fertility outcomes.” KEY MESSAGES
REASONS TO GET HEIFERS IN CALF EARLY:
AUSTRALIAN BEEF CRC- HIGH & LOW FAT LINES • Sets up the lifetime reproductive performance of
that animal.
100
• Wean heavier calves.
90 10mm • She’s more likely to get back in calf early.
Pregnancy rate (%) 80 8mm MANAGEMENT:
• She will stay longer in the herd.
70
6mm
60
can (320kg is the benchmark for maternal heifers).
50 4mm • Feed your heifers well – get them as heavy as you
2mm • Mate plenty of them, in a restricted joining period of
40
250 300 350 400 450 500 42 days (preferably).
Pre-joining weight (kg) • Sire selection – consider the days-to-calving EBV
‘Heavier and fatter heifers achieve puberty and first and foremost, but also look at scrotal size and
conception earlier.’ rib fat as threshold traits.

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