Turning up the heat on fertility

Concentrating on the basics at insemination, such as maintaining bull semen at an even temperature from flask to cow, will optimise submission rates.

Artificial Insemination (AI) expert Sean Price says when farmers can get the simple things right, their chances of getting cows in calf will greatly improve.

“Insemination is the most important period on a dairy farm because what happens then affects the farm income for the rest of the year,” says Mr Price, LIC’s artificial breeding operations manager for New Zealand’s South Island.

The block-calving farmers he advises target submission rates of 30% of the herd in the first week of AI, 60% in the second week and 90% in the third week. But a number of factors are influential in achieving these targets.

One issue influencing the mortality of bull semen is temperature spikes. Semen is stored at cold temperatures, but the temperature shoots up when it is put in a straw thawer. The temperature again fluctuates several times when it is handled and the impact this has on the mortality of the semen is quite dramatic, explains Mr Price.

“We advise farmers to keep temperatures at a rising plane by using straw warmers and immerse the straws into water at an ambient temperature,” he says.

Good hygiene and a gentle approach are essential too. “The operator must be careful not to introduce contaminants into the cervix and they must not go too fast. When the operator is rough and the cow bleeds, they might as well not have bothered.”

There are many things that can stop a cow from cycling, explains Mr Price. “She may have had a dead calf or needed assistance at calving. If she had retained her afterbirth or had an infection, the person doing the AI needs to know her history.” He advises that staff working with the herd must keep a record of this information.

“Empty cows cost farmers money. Every time a cow misses a cycle or is three weeks down the line, it extends the calving pattern. Farmers I work with in New Zealand are on a 365-day calving interval, so anything that doesn’t get in calf usually ends up down the road.”

Training farm staff to look for signs of heat is important and Mr Price believes paddock observation is vital. “The more opportunities there are to get the cow in front of the bull, the more chance there is of getting them in calf. Everyone on the farm needs to be trained to know what to look for, even the tractor driver. If he sees a cow bulling he needs to know to write down their number, it is another set of eyes.”

Additional tools, such as tail paints and KAMAR detectors, are useful aids, he adds, but they are no substitution for regular paddock observations. These should be done twice a day, in the morning and evening. The ideal time is about two hours after they have returned to the field.

An LIC trial on the time of day insemination is carried out showed the difference was negligible, but what is critical is that it is carried out at the same time every day. A 24-hour cycle is critical.

“It’s no good having a 22-hour gap one day and 28 hours the next. The cycle from standing heat is 24 hours,” adds Mr Price.