Clues to in-calf conundrum

And judging by comments made by LIC’s Amy Frampton to a focus day on the farm last month, it’s a common conundrum.

“Why have we got this 6% drop in in-calf rate? I’ve been on lots of other farms trying to answer that question too,” she told the focus day crowd, urging them to work through the eight slices of a fertility “cake” to identify possible causes (see box).

In LUDF’s case, body condition was “fantastic at calving” and at mating only 4.6% of the herd was below body condition score (BCS) 4.0. Breaking down in-calf rates by BCS showed 76% of those at 4.5 in-calf at six weeks, 73% of those at 4.0 in-calf, and 60% of those at 3.5 or 5.0 in-calf.

“Girls in that 4.0 to 4.5 condition score range do very well reproductively,” Frampton stressed.

Looking at production didn’t reveal a link either. “The high producing cows got in-calf well and were actually the best. They had a 77% six week in-calf rate at Lincoln compared to the average of 72%.”

Frampton admitted that with nothing “jumping out” as a cause from condition and production, they were starting to get frustrated but an “a-ha!” moment came when they analysed in-calf rates against calving date.

The medium calvers – those calving at three-six weeks from planned start of calving – were only 61% in-calf at six weeks, compared to 78% of the early calvers. That drop of 17 percentage points was well over the industry target of 10 points, and Lincoln’s 2013 eight-point drop.

“Also the conception rate was 13 [percentage points] lower than the early calvers’,” noted Frampton.

However, again there was no obvious reason why this group of cows were below par: they were in good condition, the weather was mild and they had plenty of high quality pasture.

Protein to fat ratio of milk didn’t show any abnormalities and retained membranes or still births were few in the group too. But when it came to dirty cows, a red flag went up. There was a 7.5% incidence compared to 1.5% the previous year.

“We’ve calculated those dirty cows pulled the whole herd conception rate back 2%.”

So why so many dirty cows? Frampton suggested a slight deficiency in selenium or calcium, both important in uterus cleansing, as possible causes.

One thing it certainly wasn’t, she added, was heat detection, as cows were bulling “long and strong” and the LUDF team did a “fantastic job” with submission rate being similar to 2013.

Summing up, Frampton said the analysis shows body condition at calving is critical and preserving body condition in late lactation is vital. “Try not to be too greedy. Don’t keep milking into June.”

That’s particularly important with some “scary looking” winter crops in Canterbury due to the drought. “You’ve got to know where you stand, what you’ve got available to feed.”

Feeding well during calving to keep appetite going is important and “health events” should be recorded for future reference. If in-calf rates are over 70% then analysing performance by groups of cows, as they had at LUDF, could keep pushing reproductive performance. “The challenge is to work out who let you down.”

Tools such as LIC’s online Minda software could help. “Do use it, it does a lot of the work for you.”