GOOD heifers are the result of good planning. Just ask the Glennens.
Siblings Con, Jack and Bernadette Glennen, along with their nephew Con Glennen and his wife Michelle, take breeding replacement heifers very seriously in their 350 cow Jersey herd at Noorat in Western Victoria.
The herd has been bred using artificial insemination and herd recording since the early 1970s and no replacement heifers have come into the herd unless they are sired by AI bulls.
The emphasis on having enough well bred heifers means that the Glennens use 600 to 700 a straws a year to produce their 100 replacement heifers.
And while the Glennen family see themselves as commercial dairy farmers rather than stud breeders, their efforts in breeding stand them in the Top 5 for ASI within the Jersey breed.
The herd has been in the family since the 1930s and today is made up of 350 cows with calving split between March/April and August/September.
All heifers are joined at 15 months to AI using heat detection for three weeks followed by a team of bulls.
Autumn calving cows are joined to AI over six weeks followed by bulls, while spring calving cows have a nine week AI joining with no bulls.
Any calves sired by natural joinings are sold and only AI bred heifers are kept for replacements.
“There are enormous benefits in only keeping AI bred heifers,” Jack said.
“Every cow- except for an obvious cull - has the opportunity to get in calf with AI before the bulls go out.
“Over the years we’ve seen the production of the cows almost double and at the same time we’re running more cows on the farm.” Said Con.
Using 6 straws to produce a replacement heifers is a new ‘rule of thumb’ for the Australian Dairy Herd Improvement Scheme, and simple maths for Con and Michelle Glennen.
This rule of thumb allows for a 50% conception rate, 10% loss of cows prior to calving (eg. pregnant cows that are culled for other reasons), 50% female calves, 5% loss of heifer calves prior to weaning, 5% loss of heifers prior to joining, 90% heifer conception rate, 3% losses prior to calving (deaths, slips) and 3% heifers exiting the herd in the first 30 days post calving.
“We need to use 600-700 straws each year to be sure we will have our 100 or so AI bred replacements coming though and into the herd.”
The expenditure of AI is a sound investment according to the Glennens, with the returns evident in the genetic improvement in the cattle and the herd’s production.
“If you want the returns then you need to invest in the herd - it costs just as much to rear a bad heifer as it does a really good one, so we’d rather put our efforts into just rearing AI bred heifers,” Con said.
“When you start getting AI-bred heifer calves out of first calving AI-bred two year old heifers then you can really fast track the rate of genetic improvement in the herd.”
The Glennens' efforts have been recognised with a number of their White Star Jersey bulls being successful in progeny tests teams and cows regularly ranked in the Top 100 Jersey cows for ASI..
Michelle Axford, from the ADHIS, said the real value of AI straws is the genetic merit of the heifers when they enter the milking herd.
“The decisions you make today on the number of straws and the quality of the bulls used this season will affect the genetic merit of the herd for many years to come.” Mrs Axford said.
InCalf’s Barry Zimmermann suggests farmers plan three years ahead and decide how many replacement heifers they’ll need entering the herd and allow six straws this joining for every replacement heifer needed in three years.
“This approach helps you think about where you want the herd to be in three years time, especially if you plan to expand, and ensures you’ll have enough replacement heifers without scratching around at the last minute buying extras,” Dr Zimmermann said.
For more information contact ADHIS on (03) 86 214240 or email@example.com