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One hundred-sixteen Holstein heifers (mean BW, 175 kg) were randomly assigned to diets of alfalfa silage or corn silage and were fed to gain approximately 725 or 950 g/d in order to study the influence of prepubertal diet and rate of gain on mammary growth and milk production. Blood was collected before puberty for hormone determination, and 8 heifers per(More)
Holstein cows were killed at three physiological stages, prepartum (-7 d, n = 10), early lactation (63 d, n = 7), and late lactation (269 d, n = 8), for determination of chemical composition and prediction of energy changes during lactation. Cows were weighed, slaughtered, and separated into five or six fractions, including carcass, gastrointestinal tract,(More)
The role of trans-C18:1 fatty acids in milk fat depression was examined. Six rumen-cannulated Holstein cows were assigned to two Latin squares with 21-d periods. The common basal diet contained 40% forage and 60% concentrate. Treatments were the uninfused control, 750 g/d of a mixture of cis fat (65% high oleic sunflower oil and 35% cocoa butter), and 750(More)
Growth components were compared in an experiment with a 2 x 2 factorial design. Eight replicates of Holstein heifers were fed diets based on either alfalfa or corn silage for daily gain of either 725 or 950 g from 181 to 334 kg of body weight (BW). Mean daily gains from corn diets were greater than gains from alfalfa diets for BW, udder, empty body, fat,(More)
Seventy-five prepubertal heifers were fed diets based on either alfalfa silage or corn silage plus soybean meal for daily gains of either 725 or 950 g/d in a 2 x 2 factorial. Heifers were fed from 175 to 325 kg of body weight (BW). The alfalfa diet contained more digestible protein and less digestible energy than did the diet containing corn silage plus(More)
To develop equations for predicting body composition, mature Holstein cows (n = 21) were slaughtered at three physiological stages (-7, 63, and 269 d postpartum) after consecutive intravenous dosing with urea and D2O. Blood was sampled at 0 and 12 min after dosing with urea for determination of urea space and from 0 to 72 h after dosing with D2O. Empty body(More)
Metabolic and endocrinological characteristics were compared for cows that differed in the extent of milk fat depression. Forty-one multiparous Holstein cows were fed control (40% concentrate and 60% forage) and high concentrate (80% concentrate and 20% forage) diets in a doubale-reversal design. Cows showing one or more percentage units of depression in(More)
This experiment determined the effects of infusion of mixtures of fat containing predominantly cis-C18:1 or trans-C18:1 fatty acids into the abomasum on responses of cows to glucose and norepinephrine challenges administered i.v. Six lactating Holstein cows, each with a rumen cannula, were arranged in two Latin squares with 21-d periods. The common basal(More)