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Recent research on the effects of excess dietary nitrogen on the fertility of dairy cows
  1. R. A. Laven, BVetMed, PhD1,
  2. R. J. Scaramuzzi, BSc, PhD, DipRepPhys2,
  3. D. C. Wathes, BSc, PhD, DSc2,
  4. A. R. Peters, BVetMed, MA, PhD, FRCVS3 and
  5. T. J. Parkinson, BVSc, DBR, DipECAR, MEd, PhD, FRCVS1
  1. 1 Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand
  2. 2 Department of Veterinary Basic Science, Royal Veterinary College, North Mymms, Hatfield AL9 7TA
  3. 3 Pfizer, Ramsgate Road, Sandwich CT13 9NJ


High concentrations of dietary nitrogen have been associated with reductions in the fertility of dairy cows, but the evidence is not conclusive and many studies have shown little or no effect. This paper reviews recent investigations of the effect of rapidly degradable sources of nitrogen on parameters of fertility, and concludes that high levels of dietary nitrogen do not routinely reduce fertility, even at intakes above those in normal dairy cow diets. It also concludes that cows may be able to adapt to high nitrogen diets so that diets that may reduce their fertility when introduced at critical periods, for example, when they are inseminated, do not reduce it when introduced at an earlier stage.

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