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Feeding for fertility this breeding season

Feeding for fertility this breeding season

This spring was a game of two halves, in terms of herd feeding management. The good weather in February saw cows out to grass and intakes were good overall.

Things were a bit more challenging in March due to bad weather; however, the consensus among many discussion groups has been that cows have emerged from the first round in relatively good condition. As we move closer to the start of breeding, we need to make sure we continue to set up the herd for good pregnancy rates.

Body condition score (BCS)

BCS at breeding should be 2.75 plus, to improve conception rates. What if some cows are still well below target at the start of breeding? It will take a couple of months to fix very thin milking cows by feeding 2-3kg extra meal. Short-term improvements in conception rate will be minimal. If there are thin or non-cycling cows in the herd that are due for breeding, milking once-a-day for six weeks can boost fertility.

High EBI cows (€180+)

These cows will maintain BCS across a range of diets, explaining in part why their fertility is better. Use highEconomic Breeding Index (EBI) bulls (target €300+) to make feeding for BCS simpler in the long term. The BCS response to extra feed is poor in the short term for lower-EBI herds.

Energy intake

This drives milk solids, maintains BCS, and improves fertility. Ensure that the herd is grazing the best quality grass possible (1,400kg covers, three leaf stage). Watch residuals (target 4-4.5cm) to make sure cows are cleaning out paddocks but not being pinched on intake. Supplement deficits in grass in good time. Well-fed herds will be eating 18- 19kg DM at grass in April.

Protein in the diet

High quality pasture contains a high level of crude protein N, which milking cows use with feed energy to make milk protein. Surplus diet N may cause elevated milk urea levels; however, under good management, bulk milk urea does not explain much difference in fertility between herds. Apply fertiliser N in small-and-often batches during the breeding season. Do not overload fertiliser N under drought conditions, and feed high energy 14% crude protein rations at grass to control any risk.

Mineral deficiencies

Phosphorus (P) deficiency can be an underlying cause of low conception rate. If cows are licking stones, exhibiting depraved appetite, etc., it is important to act early. Blood test 7-10% of the herd and speak to your Teagasc advisor on results. You may need to add extra P to water, as mineral blocks or in-ration boluses will not correct a P issue. Trace minerals (copper, cobalt, iodine, selenium, manganese and zinc) are needed in tiny quantities, but can affect fertility if lacking in the diet. Feeding minerals above requirements is expensive and will not boost fertility where no deficiency exists. The problems of thin cows, poor heat detection and bad genetics are usually much more important.