T E C H N I C A L
Science in to on-farm practice: reaping the IVP rewards “Genetic improvement is generally a slow and gradual process, a view most Beef Shorthorn breeders could concur with.
“G
enetic turnover time is around two years and nine months, when calving at two years, so selection decisions made now can take over five years to effect,” says Dr Gerard te Lintelo.
“Breeding to improve cattle requires a clear plan.” he says. “You need focus and a goal to aim for. Our objective is to breed profitable cattle which have a commercial purpose for both suckler and dairy producers.” His Mayfield herd was established in 2017 with five purchased heifers within the breed’s top 10%. “My goal is to build the herd to 120 to 140 breeding females to be able to offer different genetics for different purposes. So far, the herd amounts to 40 cows and accelerating genetic progress while increasing the amount of breeding animals are among the immediate priorities. To breed one or two outliers a year would be a bonus, but there lies the challenge,” he says. “Mayfield Rubens for example has so far made the cut. He combines some of the best UK and Canadian genetics.” His terminal index, self replacing index and maternal index are all within the breed’s top 1%, while both his sire and dam linear classified very high. “I’ve been selecting from my herd’s top 15% for IVP - the breed’s maternal traits are paramount, along with those which enable Beef Shorthorn cattle to grow and finish really well from low input, forage based systems. I’m widening the herd’s gene pool by importing genetics from Canada and Australia bred for these low-input systems.”
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B eef Shorthorn C attl e S oc i ety J o ur n al 2 0 2 3
Initially Gerard used conventional embryo transfer (ET) to step up the herd’s genetic progress. However, over the last two years, AB Europe’s In-Vitro embryo Production (IVP) has come into the frame. IVP is a process which produces embryos from harvested oocytes (unfertilised eggs). These oocytes are directly collected from the ovaries after a short super-ovulation program. The oocytes are fertilized in the lab with selected semen and subsequently cultured for seven days. The embryos can then be transferred fresh or can be frozen for later use. “In 2022, we used six in-calf cows for IVP which resulted in 98 oocytes collected. They were taken back to the lab and the following day four different straws of semen were used, and 36 embryos were produced,” he explains. “A week later 14 fresh embryos were implanted in our synchronised recipients, resulting in a good hold rate. The remainder were frozen for future use or might be sold. We achieved similar success in 2021; a flush of 46 oocytes from five cows resulted in 18 embryos; 12 were implanted with seven
