Large herds and high yields present a double challenge when it comes to getting cows back in calf. A Shropshire herd – numbering 650 Holsteins and averaging 11,000kg – has found that strategic hormone treatment is a cost-effective method of getting cows pregnant.
And with staff numbers rising from three to four, herd manager Andrew Sanderson now hopes the team will have more time to focus on those other fertility factors – heat detection, lameness and cow health. In the past decade, he has overseen the increase in herd size at Stockton Grange, Newport, from 160 cows – and there are long-term plans for 1000 cows.
“We calve all year round, house all year round and milk three times a day. We have cows giving 16,000kg and we feed a TMR, with concentrates in the parlour,” says Mr Sanderson, who is employed by Heaths of Stockton.
He has no doubts fertility may suffer as cow numbers rise, management changes – and for a time, there are fewer staff: “It was difficult just to get routine things done,” he says. But the herd’s 410-day calving index and 41% conception rate to first service aren’t bad for such a high herd average, he believes.
Heat detection is based on checking cows at least four times a day, with Kamars used as an aid. Mr Sanderson also finds that a high conductivity reading in the parlour either highlights a sick cow, or one in oestrus.
A recent switch to a shorter dry period of 40 days (45 for heifers) has helped improve cow condition and avoid negative energy balance after calving. Management tries to reduce stress on cows by minimising changes, too. The farm’s routine fertility visit has also changed as cow numbers have risen.
The fortnightly visit would take half a day when as many as 100 cows were put forward for checking. “So when we had a problem, such as displaced abomasum, it took even more time. Now we have split the visit in two: Once a fortnight, on Tuesday, vet Bill May of Lambert, Leonard & May scans for PDs then comes back on Thursday to check non-breeders,” explains Mr Sanderson.
“At least 15-20% of cows presented as not seen bulling turn out to be on heat. It’s surprising how many don’t ovulate. This is when we use Receptal, particularly for any cow more than 120 days calved and having had three or more serves. We jab her and AI after the vet visit. If we can encourage ovulation, we’ve got a good chance of getting a pregnancy.”
A second use of Receptal takes place on day 11 or 12 after a cow has been served. “It’s not very often and it’s to help the pregnancy, and we do it for cows that have had more services than we’d like. We don’t use it across the whole herd because you can soon spend a lot of money and still get just an 11% increase in pregnancy rate. We need to manage costs and if you choose cows, you get better results.”
Injecting cows can help when staff don’t see bulling
One of the largest categories of cows seen by vet Bill May at routine fertility check is NSB – not seen bulling. He estimates at least one-third of such cows are on heat the day he examines them.
“It’s a particular problem in large herds because oestrus detection is more of a challenge. The numbers alone make it more difficult, but new set-ups tend to mechanise jobs such as scraping out, bedding and feeding, so staff are no longer among cows for heat detection,” he explains.
Not only that, modern cows are harder to catch on standing heat. US research has revealed the typical high-yielding Holstein is in oestrus for a shorter period of time: 6.2 hours compared with 10.9 hours for an average-yielding cow. And she mounts just six or seven times (instead of the average cow’s eight or nine), each one lasting 8-9 seconds.
However, there is help for the NSB cows at the vet check. They can be given a shot of Receptal, which contains buserelin. This works in the same way as gonadotrophin, releasing hormone, stimulating production of follicles and hormone and luteinising hormone from the pituitary gland to influence the ovary.
“An injection stimulates final maturation of the follicle and ensures ovulation on time for sperm to be present. These cows are served later the same day,” adds Mr May.