Samples were analyzed from three metabolism trials to evaluate the effects of dietary phosphorus (P) intake on P excretion in beef steers fed corn-based finishing diets. In Experiment I, ten steers were fed ten diets that involved two processing methods, whole and dry rolled corn and five corn sources, commodity, white, high oil, high protein, and highoil-high-protein corn. In Experiment II, six steers were fed three diets that included three variations of protein supplementation to meet 70, 80, and 100% of the degradable intake protein requirements for growing steers. In Experiment III, ten steers were fed five diets including control, 4% or 8% distillers solubles, and 10% or 20% wet distillers grains. For all experiments total urine and feces, feed intake, and feed refused were measured during a 5-d collection period, following 9, 10 and 14-d of dietary adaptation for the three respective experiments. Dietary P concentration (% DM) and dietary P intake (g/d) ranged from 0.31 to 0.36 and 21.5 to 27.2, 0.28 to 0.29 and 19.8 to 21.2 and 0.29 to 0.40 and 22.9 to 34.5 in the three respective experiments. Total P excretion was significantly related to P intake, but there was considerable variation among steers in partitioning excretion of P in urine or feces. Urinary P excretion (g/d) ranged from 3.0 to 7.4, 3.1 to 4.3 and 4.3 to 7.5 in the three studies, respectively. Replacing corn grain with corn processing co-products increased P intake but did not significantly change excretion patterns.

A line of Yorkshire pigs was selected for 3 generations for reduced residual feed intake (RFI), a measure of feed efficiency defined as feed consumed over and above average requirements for maintenance and growth. Heritability estimates of RFI, feed intake, growth, and backfat were 0.30, 0.46, 0.33, and 0.67. Comparison of performance of gilts from the selected line (n=49) to those of a randomly selected control line (n=38) from ~40 to ~70 kg showed that selection had significantly decreased feed intake by 123 g/d. There were no significant differences in average daily gain and backfat between the lines, although the selection line tended to have 22 g/d less growth. In conclusion, RFI is a heritable trait and selection for RFI has significantly decreased the amount of feed required for a given rate of growth and backfat.

Iowa has led the U.S. in swine production and pig inventory since the 1880s. Pig production has been a reliable value-added enterprise on many Iowa farms for generations. In spite of this 120-year national leadership, Iowa’s swine industry has been changing profoundly within the state.

The rumen bolus electronic animal identification system was evaluated in 120 feedlot steers during a 130 day observation period. Boluses were placed in the reticulum using a balling gun. A panel antenna was located inside (left side) of a hydrolytic restraining chute placed on load cells and connected to a Tru-Test scale indicator to display and store the electronic identification number and weight of the animal. Once displayed on the indicator the identification number and weight were stored in a file in the indicator which was later downloaded as an Excel file. Using Data/Sort in Excel the new data could easily be matched with animal Id numbers in an evolving file for the experiment. All of the boluses were retained in the animals and all remained functional. The system accurately recorded the information for 711 of 720 times the animals were weighed, or an accuracy of 98.75%.