This episode takes a deep dive into the topic of dietary iodine requirements of cows - and the relationship (or not) of iodine intake with the reproductive performance of cows. Iodine is well down the priority list when tackling challenges of poor reproductive performance. Body condition score at calving and the extent and duration of body condition loss (‘negative energy balance’) are by far the more important factors that drive successful reproductive outcomes in dairy cows. That said, iodine features every season in conversations on farm about improving mating outcomes. “Iodine improves expression of heat by cows” has been around for a long time as a topic of conversation. Fact or fiction? Join us in this latest podcast to explore the potential relationship between dietary intake of iodine by cows (and some discussion of ewes too) and the wellbeing of ruminants. As always, the content of this podcast is of a general nature only and is never intended to replace the advice of your very own local veterinarian and qualified dairy nutritionist. Where to find different parts of this podcast: 1.20 Overview of the topic of iodine and the reproductive performance of pasture-fed dairy cows 1.55 Iodine might play a possible role in cow fertility but more than 100 other factors determine if cows will mate successfully – particularly cow body condition score at calving and extent and duration of body condition loss between calving and mating 5.00 Iodine increases expression of signs of oestrus (heat) by cows – fact or fiction? 7.45 Why do cows require iodine in their diet? It’s all about thyroid hormones, needed particularly by the unborn calf. 9.30 What do thyroid hormones do inside the cow (and unborn calf) or indeed inside the ewe (and unborn lamb) 12.00 Goitre in newborn calves and lambs – very rarely seen in adult stock 14.10 Aside from clinical signs in newborn animals born to cows and ewes, there’s not much to see in iodine deficient cows and ewes 16.40 Iodine and the functionality of the reproductive system in cows 17.00 The “HPO” axis that drives reproductive function and the role for iodine 18.45 Possible changes to reproductive function when iodine status is low 22.30 The challenges of diagnosing iodine deficiency in cows (but discuss this topic further with your vet) 25.15 Pasture levels of iodine are very variable! 25.50 Salt spray off the sea – adds small amounts of iodine to pasture 26.30 Other factors that influence iodine intake by pasture-fed cows 27.05 Goitrogens in forage feeds – reduced conversion of iodine to thyroid hormones 29.05 Types of goitrogens in NZ forages 31.50 Iodised teat sprays and iodine status of lactating dairy cows 33.25 Taking the simple approach, not testing for iodine, can we just add iodine to the diet? 33.55 Care with supplementing with iodine, some countries, upper limits to iodine supplementation! 34.20 Selenium deficiency contributes to thyroid hormone challenges as well

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“What did the council decide on item 42?” — answered with the speaker and the moment.

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