Forty Holstein and Jersey cattle were assigned to four groups by milk production of Dairy Herd Improvement Association records. Cattle were on pasture and free-choice roughage supplemented with a concentrate and mineral mixture that was mixed without iodine supplementation. Teats of cows in each group were dipped for 27 days with chlorhexidine (controls) or iodophor teat dips with 1, .25, or .1% concentrations of iodine. Individual milk samples were taken on days 0, 20, and 27 for determination of iodine in milk. Mean iodine remained fairly constant, although there was a transitory increase for 1 and .25% dips at day 20. Mean iodine in milk (microgram/liter) for days 0, 20, and 27 were control: 31.3, 19.8, 14.7; 1.0%: 21.8, 51.5, 23.7; .25%: 34.5, 46.9, 36.7; .1%: 13.6, 14.5, 14.9. Iodophor teat dips did not add appreciable amounts of iodine to the bulk milk.

Due to concerns about high I in milk, the dairy industry has proposed a voluntary standard of 500 micrograms of I/L as the maximum allowable I in milk sold for processing and human consumption. This study was undertaken to determine the amount of ethylenediamine dihydroiodide that could be fed to dairy cattle without exceeding this standard. Various amounts (0 to 45 mg/head per d) of the I compound were fed to a commercial dairy herd for 50 wk. Individual and bulk milk samples were analyzed for total iodine. Milk I in herd bulk milk was directly correlated (r = .92) with the amounts fed. However, the correlation of milk I of individual cows was not as high (r = .66), indicating some individual variation in metabolism and secretion of the I into the mammary gland. Milk production and number of lactations did not correlate with I in milk. Regression analysis indicated that 25 to 30 mg of ethylenediamine dihydroiodide per day can be fed to dairy cattle receiving a diet otherwise low in I without exceeding a 500 micrograms concentration in milk.

Lactating cows require complete balanced rations to meet their high nutritional requirements and to maximize milk and milk fat production. Total mixed rations (TMR) were developed to meet these nutritional needs by thoroughly mixing necessary feedstuffs into a single ration; hence providing a balanced diet in each bite. However, the actual nutrient and fiber concentration consumed by cows can dramatically differ from that of the ration due to selective feeding. The objectives of this study were to 1) evaluate the palatability of alfalfa hay TMR and alfalfa baleage TMR and 2) determine the effect of TMR fiber sources on the preferential sorting of rations. Sixty-four lactating dairy cows at the R.T. Wright University Farm at Northwest Missouri State University, Maryville, Missouri, were fed TMR containing either 35 percent alfalfa baleage or 35 percent alfalfa hay. Fresh TMR was weighed and distributed evenly within the feed bunk every 24 hours and orts (unconsumed feedstuffs) were collected and weighed to determine the amount of feed consumed. Feed samples from the bulk ration and arts mixture were collected for analysis of particle size distribution via a Penn State Particle Separator. Results indicate the cows clearly preferred shorter (< 0.79 cm) feed particles in both the baleage TMR and hay TMR. In addition, the cows preferred and consumed more alfalfa baleage TMR than alfalfa hay TMR. No relationships between moisture content and TMR preference were identified.

No abstract

No abstract