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Official methods were used to analyze composite samples of milk collected during the first 15 wk of lactation from 21 Holstein cows fed a milled ration containing 0 (basal), 15% (medium, or 30% (high) protected-tallow supplement (seven cows per treatment). Protein fractions and amino acid composition of the total proteins were determined from samples of individual milking. Melting characteristics of pooled samples were determined by nuclear magnetic resonance. Milk yield was similar for the three treatments, but percent fat and fat yield were higher for cows fed protected tallow. Percentages and yields of protein and solids-not-fat were decreased on the protected tallow treatments, especially for high tallow. The decrease in protein was in the casein fraction. Amino acid composition of the total proteins was similar for the three treatments. Feeding protected tallow caused decreases in all fatty acids except 4:0, 16:1, 18:0, and 18:1 which increased. Nuclear magnetic resonance indicated that butter from the basal group would be harder than that from cows fed protected tallow.

Thirty-eight older (second and greater lactation) and 15 Holstein cows in first lactation were in a full lactation (44 wk) study to evaluate the effect of either twice or three times daily milking on yield of milk and milk components, milk composition, feed intake, and body weight change. All cows were managed alike and were fed diets of high, medium, and low energy concentration as lactation progressed from calving to 44 wk. First lactation cows were switched from diets of high energy to lower energy at the same milk production as lactation advanced. Dietary changes for older cows milked twice and three times (A) were at similar production, whereas three times (B) cows were switched to lower energy at higher milk production. Older cows milked three times daily (A and B) produced 17 and 13% more milk over the entire lactation than cows milked twice daily. Dry matter and energy intakes were not affected by three times milking, but gain of body weight was reduced. Cows milked three times daily during their first lactation produced 6% more milk than their twice counterparts, although this increase was not significant. Dry matter and energy intakes were not affected by three times daily milking, but three times milking of first lactation cows reduced weight gain over the lactation. Reproductive performance of cows milked three times daily was not significantly different from cows milked twice daily. Herds milking three times will require high management of nutrition and reproduction.