Block calving is key (From Western Telegraph)

Block calving is key

Farmers can achieve above average herd fertility by block calving and targeting good submission rates according to Pembrokeshire dairy farmer Kim Petty.

Replacements have more than doubled cow numbers at Tyddyn-yr-Eglwys, the 129 hectares which Mr Petty farms near Crymych. Poor diet and mineral deficiencies are unfairly targeted for blame when a herd has poor herd fertility, he believed.

He targets a 95% submission rate in the first four weeks of the service period and the whole herd is served within seven weeks. Statistics put the national submission rate at below 70%. "If a herd has a conception rate of below 50%, which is happening, particularly in all-the-year round calving situations, a farmer will only get 35% in calf in the first three weeks. This is a real issue,'' he said. For the last three years, he has achieved a first service conception rate of 60% for cows and over 70% for maiden heifers.

Block calving has been key to attaining these figures. "One of the real benefits of block calving is that there is two months to get everything cycling before the service period. We AI for six weeks using New Zealand Friesians on cows and New Zealand Jerseys on the heifers. The advantage is that we are breeding from our most fertile cows. That's how the whole process starts feeding on itself. When you start getting surplus stock you know you are getting successful at it.''

But he admits he doesn't get it right every time. This spring his conception rate fell to 55%, a problem he attributes to poor quality silage and its consequential impact on cow condition. But, thanks to high submission rates and heifer numbers, he still expects over 150 cows and heifers to calve in the first three weeks.

Breed history is important when considering dairy replacements, he added. "It is necessary to select bulls with a pedigree showing good fertility and longevity where the dam and grand dam have a good lifespan, producing a calf every 365 days. It is no good for a block calving herd to breed from a bull whose dam only produces a calf every 18 months.''

He favours New Zealand Friesians because, in his opinion, the breed is robust, holds its condition and, above all, gets back in calf easily. "I like Friesians because I hate losing cows. It concentrates the mind when you are block calving because you sell all your barren cows in one go. It hurts when a cull cow is worth between £200 and £250 compared with £1,000 for a good milking cow.''

Mr Petty introduced ten Jersey crossbreds into his herd this spring, bringing his cow total to 220. He is so pleased with their performance he may increase numbers. He attaches value to the need to meet sufficient live weight targets for heifers. His cows are dried off to allow them to calve down at a condition score of 3.2. He vaccinates for leptospirosis a month before serving and gives the stock access to a good quality mineral during the dry period.

Diet is critical to boosting his herd fertility. "Negative energy balance can create fertility problems,'' he says. He feeds citrus pulp, maize gluten mix or beet pulp, at a maximum of four kilos when grass is in short supply at the start of the season. "The cows should be fully settled on a diet three weeks before serving and preferably on a rising plane of nutrition,'' he believes.

"The easiest way to improve cow fertility is to fully feed the cows. In my opinion it doesn't make a difference to conception rates if they are only fed on grass, as long as they are fully fed.''