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Title: Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but increase milk iodine output in early lactation dairy cows fed high-forage diets

Author
item ANTAYA, NICOLE - University Of New Hampshire
item Soder, Kathy
item KRAFT, JANA - University Of Vermont
item WHITEHOUSE, NANCY - University Of New Hampshire
item GUINDON, NICOLE - University Of New Hampshire
item ERICKSON, PETER - University Of New Hampshire
item CONROY, ANDREW - University Of New Hampshire
item BRITO, ANDRE - University Of New Hampshire

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2014
Publication Date: 12/26/2014
Citation: Antaya, N.T., Soder, K.J., Kraft, J., Whitehouse, N.L., Guindon, N.E., Erickson, P.S., Conroy, A., Brito, A.F. 2014. Incremental amounts of Ascophyllum nodosum meal do not improve animal performance but increase milk iodine output in early lactation dairy cows fed high-forage diets. Journal of Dairy Science. 98:1991-2004.

Interpretive Summary: Kelp meal (Ascophyllum nodosum) is being fed to dairy cows as a mineral-rich supplement. However, kelp meal contains significant levels of iodine which may be of concern to human health due to iodine toxicity. We evaluated the effects of feeding increasing levels of kelp meal to lactating dairy cows on feed intake, milk production and iodine levels in milk. Cows fed iodine did not consume more feed nor produce more milk; however, milk iodine levels increased as level of kelp meal increased in the diet. Because the milk iodine concentration reached levels that may be toxic to humans, particularly children, high levels of kelp meal supplementation to dairy cows should be done cautiously.

Technical Abstract: The objective of this study was to investigate the effects of incremental amounts of Ascophyllum nodosum meal (ANOD) on milk production, milk composition including fatty acids and I, blood metabolites, and nutrient intake and digestibility in early lactation dairy cows fed high-forage diets. Twelve multiparous Jersey cows averaging (mean ± standard deviation) 40 +/- 21 days in milk and 464 +/- 35 kg of body weight and 4 primiparous Jersey cows averaging (mean +/- standard deviation) 75 +/- 37 days in milk and 384 +/- 17 kg of body weight were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Cows were fed a total mixed ration (64:36 forage to concentrate ratio) supplemented (as fed) with 0, 57, 113, or 170 g/d of ANOD. Milk yield as well as concentrations and yields of milk components (fat, protein, lactose, milk urea N) were not affected by increasing dietary amounts of ANOD. Concentration (from 178 to 1,370 ug/L) and yield (from 2.8 to 20.6 mg/d) of milk I increased linearly in cows fed incremental amounts of ANOD as a result of the high concentration of I (820 mg/kg dry matter) in ANOD. Overall, only minor changes were observed in the proportion of milk fatty acids with ANOD supplementation. Quadratic trends were observed for dry matter intake and total tract digestibilities of organic matter and neutral detergent fiber, while negative linear trends were observed for serum concentration of cortisol and crude protein digestibility with ANOD supplementation. Serum concentrations of triiodothyronine and thyroxine were not affected by ANOD supplementation and averaged 1.1 and 48.4 ng/mL, respectively. However, feeding increasing amounts of ANOD linearly reduced the plasma concentration of nonesterified fatty acids (from 164 to 132 mEq/L). Quadratic effects were found for the total tract digestibility of ADF and urinary output of purine derivatives suggesting that ANOD supplementation may stimulate growth of ruminal cellulolytic bacteria in a dose-dependent fashion. In general, feeding incremental amounts of ANOD to early lactation dairy cows dramatically increased milk I concentration and output with no effect on animal performance.