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Feeding for fertility in the lead up to breeding season

Nutrition plays a vital role in achieving good herd fertility. Quality of feeding in the dry period and early lactation can affect outcomes. Teagasc specialist Joe Patton gives advice on getting nutrition right before breeding.

There are many issues cannot be solved by just looking at the diet during the breeding season itself. It remains important to get some key targets right however: 

  • Body Condition Score (BCS) at breeding should be 2.75 plus to improve conception rates. What if some cows are still well below target at 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 6 weeks can boost fertility
  • High EBI cows have been proven to maintain better BCS across a range of diets, explaining in part why their fertility is better. Use high EBI bulls to make feeding simpler in the long term.
  • Energy intake drives milk performance, maintains BCS, and improves fertility. Ensure that the herd is grazing the best quality grass possible (1400kg covers, 3 leaf stage). Watch residuals (target 4cm) to make sure cows are cleaning paddocks but not being pinched on intake. Supplement deficits in grass in good time.
  • Protein in the diet- high quality pasture contains a high level of crude protein (Nitrogen) which milking cows use with feed energy to make milk protein. Surplus diet N may elevate blood and milk urea levels and this may give rise to concerns on fertility. Under good management, bulk milk urea does not explain much difference in fertility between herds. Apply fertilizer N small-and-often during the breeding season, do not overload fertilizer N under drought conditions, and feed high energy 14% crude protein rations at grass to control any risk.
  • Major minerals calcium, magnesium, sodium and phosphorus should be supplemented to requirements at least into the second rotation and longer if needed. Many herds experienced phosphorus issues during the early season drought in 2020 which may have impacted on fertility. Cows licking stones is a classic symptom, so keep a close eye on herd behaviour. Spreading some of your annual P fertilizer allowance in early April can boost sward P levels to benefit the diet also.
  • Trace minerals (Copper, Cobalt, Iodine, Selenium, Manganese and Zinc) can affect fertility if lacking in the diet. However, feeding these minerals above requirements is expensive and will not boost fertility where no deficiency exists. The ‘silver bullet’ of extra minerals will not fix the problems of thin cows, poor heat detection or bad genetics.