Room To Improve On Beef Cow Conception Rates
NEW ZEALAND - Herds with more than 90 per cent of beef cows testing ‘in calf’ are above average, according to recent analysis funded by Meat & Wool New Zealand.
31 July 2009
2 minute read
Meat & Wool New Zealand has released a four-page R&D Brief outlining a nationwide survey into what influences beef cow conception rates. The data was collected and analysed as part of the two-year Beef Fertility project run by Massey University.
“This is the most comprehensive analysis of beef fertility to date,” says Meat & Wool New Zealand Farm Services Research Manager, Dr Andy Bray. “Data was taken over a three-year period and 200,000 cows were included. In-calf rates were adjusted for herd size, stocking rate, terrain, region, and mating and calving paddock safety, so a true average rate could be found. The project also broke new ground in that it was the first time that the effect of cow condition score and bull:cow mating ratio on fertility had been quantified.”
Results from 978 farms show that the average in-calf rate after 63 days of joining with the bull was 90 per cent. However, in a quarter of the herds less than 83 per cent of cows were pregnant.
Calf loss between pregnancy testing and marking was also analysed. The average loss was 10 per cent but it varied, ranging from 3 per cent to 17 per cent.
“This shows us that there is room to improve,” says Dr Bray. “If farmers want more calves at marking, the terrain and aspect of the mating and calving block should be as easy or ‘safe’ as possible. Conception rates were 6 per cent higher on safe paddocks. Breed choice also had an effect, with higher conception rates seen in crossbred cattle such as Friesian and stabilised composite breeds.
“Getting feeding right during late pregnancy is also important. Maintenance feeding improved conception rates by 3.9 per cent compared to restricted feeding and by 2.3 per cent compared to over-feeding. However, good condition cows during calving are a must. Analysis showed that cows with a condition score that was one standard deviation higher had a 2 per cent higher in-calf rate – a highly significant result.”
The project found the optimum ratio of bulls to cows was between 1:20 and 1:55. Running more than 55 cows to the bull started to affect in-calf rates. Around 8 per cent of farms in the survey put more than 55 cows to the bull.
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