2008 Annual Report 1a.Objectives (from AD-416) The objectives of this cooperative research project are to determine the value of dried distiller's grains as a protein supplement to cattle consuming low-quality forage, compared to more commonly used byproducts (i.e., cottonseed meal) by the effects on beef cow performance, forage intake, and nutrient digestion. To develop rapid and reliable methods to determine the nutritive value of wet and dried distiller's grains. 1b.Approach (from AD-416) Two studies will be conducted. In the first study 11 ruminally cannulated steers will be used in an 11 x 5 incomplete Latin square with 11 treatments and five periods to determine the effect of increasing supplementation with either dried distiller's grain or cottonseed meal on intake and digestion of low-quality forage. Treatments will be an unsupplemented control and dried distiller's grains or cottonseed meal at 0.025, 0.050, 0.075, 0.10 or 0.125% of body weight as crude protein. Fecal output, ruminal characteristics (ammonia, volatile fatty acid concentrations), and plasma urea nitrogen will be measured. The quantity of distiller's grains that optimizes forage intake and digestion will be determined. In the second study, 80 beef cows will be used to evaluate the use of dried distiller's grains as a supplemental protein for low-quality forages. Cows will be assigned to one of four levels of distiller's grains 0.00, 0.04, 0.08 and 0.120% of body weight as crude protein. Changes in cow weight and body condition score will be determined at intervals before and after calving, until weaning. Calves will be weighed at birth and at weaning. 3.Progress Report In a beef cow supplementation study 128 pregnant, spring-calving beef cows (Body Condition Score = 6.1 and Body Weight = 603 kg) were used to evaluate the effect of dried distiller's grains (DDG) as a protein supplement. Cows were randomly assigned to 1 of 4 paddocks from November 29, 2007, until the end of calving (April 18, 2008). Within each pasture, cows were randomly assigned to 4 treatments such that there were 8 cows per treatment in each of the 4 pastures. Treatments were 0, 1.59, 3.17, and 4.76 kg of DDG per supplementation event, with supplementation occurring on Monday, Wednesday, and Friday of each week. Due to a shortage of forage, cows were provided ad libitum access to sudan hay throughout the project. Data were analyzed as a randomized complete block design. Supplementation with DDG resulted in a linear (P = 0.006) reduction in BW loss during the supplementation period. Unsupplemented controls lost 105 kg from the initiation of the trial to calving, whereas those receiving 4.76 kg DDG lost 71 kg during the same time period. There was no difference between the treatments in calf body weight at calving. Supplementation with DDG was effective in reducing BW and BCS loss during the winter supplementation period. However, BW and BCS loss was significant for all treatments and was likely the result of the low-quality forage fed throughout the study. A forage intake and digestion study was initiated on May 28, 2008, at the Nutritional Physiology Center, College Station, Texas. Ruminally and duodenally fistulated steers are being used in a 13 x 4 incomplete Latin square. The treatments are a negative control (no supplement), 4 levels of DDG, 4 levels of cottonseed meal, and 4 levels of DDG + urea (formulated to contain the same % CP as the cottonseed meal). The 4 levels of supplementation are 52, 104, 156, and 208 g of N/kg of BW. We expect the animal portion of this project to be concluded by mid-August and the lab work to be finished by mid-December 2008. The ADODR and lead investigator are in regular contact via e-mail, phone and face-to-face contacts The ADODR monitors cooperator expenditure of funds through semi-annual reports from the cooperator and via contacts with the lead investigator.