Fertility fillip with special feed ideas
IMPROVED pregnancy rates with AI or ET in cattle have been achieved by clients of Somerset Cattle Breeding Centre since they adopted a new approach to feeding.
Based on the ideas and experience of Robert Bull (now at ADAS Bridgets, Hants) when he was with the Saintcyres herd, Devon, SCBC vet Stewart Scotts advice for maiden heifers is as follows:
For three to five weeks before embryo transfer the cattle are put on a diet which would give a daily liveweight gain of 0 to 0.25kg a day. Then five to 10 days before the expected heat date or insemination the feeding level is boosted to 0.25 to 0.5kg a day for at least four weeks.
However, that better level of feeding should not be too high. For example, rations giving daily gains over 1kg a day have been shown to reduce pregnancy rate, he says.
Most of the embryo recipients were maiden heifers and so the results are mainly for that category. But Mr Scott believes it applies to cows too, and equally to AI.
SCBC results show a 15% better pregnancy rate overall where this feeding pattern is used. But where grades two and three embryos are being transferred the new system has boosted pregnancy rate from 30.5% to 67.7%.
He is also studying the effects of a full-body clip on pregnancy success. There is some evidence that it may be beneficial, he says, probably because clipped cattle eat more.