To evaluate the influence of mass of ruminal contents on voluntary intake and ruminal function, five ruminally cannulated steers (550 kg) were fed an orchard grass hay diet ad libitum in a 5 x 5 Latin square experiment. The mass of ruminal contents was altered by adding varying weights of modified tennis balls to the rumen before the initiation of each 15-d experimental period. Treatments consisted of 50 balls with a specific gravity of 1.0, 1.1, 1.2, 1.3, or 1.4; the total weight of the balls was 7.45, 8.50, 9.25, 10.55, and 11.55 kg, respectively. Increasing the specific gravity of the balls added to the rumen decreased DMI and particle passage rate (P < 0.05) in a linear manner. A second experiment was conducted to evaluate the influence of mass of ruminal contents on voluntary intake and ruminal function of both forage and concentrate diets. Five ruminally cannulated steers (580 kg) were fed a 70% concentrate (DM basis) or an orchardgrass hay diet ad libitum in a 5 x 5 Latin square experiment. The mass of ruminal contents was altered as in the first experiment. Treatments consisted of 0 balls added to the rumen of steers fed concentrate diet (control), 75 balls with a specific gravity of 1.1 given to steers fed a concentrate diet, 75 balls with a specific gravity of 1.4 given to steers fed a concentrate diet, 75 balls with a specific gravity of 1.1 given to steers fed a hay diet, and 75 balls with a specific gravity of 1.4 given to steers fed hay diet. The addition of balls to the rumen of steers fed the concentrate diet decreased DMI (P < 0.05) compared with the 0-ball treatment, and increasing specific gravity of balls also decreased DMI (P < 0.01) for both concentrate and hay diets. Adding balls to the rumen of steers fed the concentrate diet decreased particle passage rate (P < 0.05), whereas increasing specific gravity of balls decreased particle passage rate for both concentrate and hay diet. The results of this study suggest that the density of ruminal digesta can have an influence on voluntary intake of both forage and concentrate diets.

Preconditioning reduces stress, maintains health, and adds value to feeder calves. Calf response to pasture nutritive value and supplementation was studied on 17 farms in 2002, 8 farms in 2003, and 9 farms in 2004. Calves were weaned in late August and backgrounded on pasture to mid‐October. Calves were fed a commercial concentrate (0.0 to 1.5% bodyweight [BW]), hay, and on some farms haylage, ground shelled corn (Zea mays L.), or soybean (Glycine max L.) hulls. Calf average daily gain (ADG) was evaluated across farms relative to animal, pasture, and supplement characteristics using multiple regressions. Commercial supplement intake, corn intake, and pasture total digestible nutrient (TDN) or pasture neutral detergent fiber (NDF) significantly influenced calf ADG. Based on regression coefficients, 4.4 lb of commercial supplement or 4.1 lb of corn were required to produce 1 lb of additional gain. Increasing pasture TDN or decreasing pasture NDF by 10 percentage units increased ADG 0.86 or 0.48 lb/day, respectively. Regressions were tested against 2004 data. Regression‐estimated gains were not significantly different from measured ADG 67% of the time. Calf performance during backgrounding can be cost effective when management ensures adequate pasture quantity and nutritive value and supplements are used judiciously relative to their cost and the value of calf gain.

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An on‐farm study was conducted to measure the effect of forage nutrive value and utilization on diet quality selected by cattle grazing rotationally stocked pastures. In New York 20 paddocks on three farms were grazed by lactating dairy cows or heifers, and in West Virginia 47 paddocks on four farms were grazed by lactating beef cows and calves or yearlings. Most pastures were grazed for one to three days. For each nutritive value component ‐ crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), non structural carbohydrates (NSC), and total digestible nutrients (TDN) ‐ apparent diet quality was calculated as the components calculated mass in the pregrazing forage mass minus the calculated mass in the postgrazing forage mass divided by the forage mass disappearing during grazing. Forage utilization was calculated as pregrazing forage mass minus postgrazing forage mass divided by pregrazing forage mass. Cattle grazed selectively increasing CP, NSC, and TDN and decreasing ADF and NDF in the apparent diet compared to the pregrazing forage. Initial pasture nutritive value had the major effect on apparent diet quality. Forage utilization modified apparent intake by reducing the magnitude of selective grazing.