@conference {89247,
	title = {Some lessons from using zinc-salt treatments to protect dairy cows against facial eczema},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {73},
	year = {2013},
	month = {Jan},
	pages = {171-174},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {<p>A trial at AgResearch Ruakura, evaluating two different methods of administering zinc++(Zn) salts to protect cows from facial eczema, was carried out in lactating dairy cows to study the variation in concentrations of blood Zn++. The treatments were: continuous supply of zinc sulphate (ZnSO4) through water troughs (n = 10 cows), versus daily oral drenching with zinc oxide (ZnO) (n = 10 cows). Responses in daily milk yields, and concentrations of Zn++in blood were recorded twice weekly over four weeks for each cow. The ZnSO4trough treatment took ten days for blood Zn++concentrations to equilibrate, after which the sampling-day average ranged from 20{\textendash}26 μmol/L. Between-cow repeatability was 0.42 {\textpm} 0.15. The daily ZnO treated cows equilibrated after drenching for three days. Average blood Zn++concentrations then ranged from 24{\textendash}29 μmol/L. Between-cow repeatability was 0.44 {\textpm} 0.17. Dailymilk yields did not differ significantly between treatments. Target ranges for blood Zn++concentrations to provide protection against facial eczema in lactating dairy cows of 18{\textendash}34 μmol/L were published 26 years ago. These may need to be re-assessed, with changes in breed composition and increases in milk yield over that time within the national herd.</p>
},
	issn = {1176-5283},
	author = {Morris CA and Hickey SM}
}
