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r- '~ score (scoring system from 1-9 wherein 1 was emaciated and 9 was obese) and ultrasound backfat thickness were collected initially and every 28 days. Forage clip samples were also taken every 28 days on all three pastures to estimate forage yield and quality. Clipped forage samples were taken at random in representative areas of the pastures using a 1 square meter plot and assuming 70% utilization. Grass and kochia were clipped separately and forage quality was analyzed by determining crude protein, acid detergent fiber (ADF), neutral detergent fiber (NDF) and in vitro true digestibility (IVTD). Samples of the diet selected by cows were collected in November and January using ruminally cannulated cows grazing the pastures. Quality of the diet selected by cows was compared to the forage quality of the available grass and forage kochia from the clip plots. RESULTS AND DISCUSSION Forage Quality Clipped forage samples of forage kochia had higher crude protein than crested wheatgrass (Table 1). This was expected because shrubs retain higher levels of crude protein than grasses during the winter. The kochia had lower NDF but higher ADF than the grass samples. The reason that ADF was higher in kochia than grass is because shrubs have higher lignin levels than grasses, and lignin is a component of ADF. Higher NDF in grasses is reflective of higher levels of fiber in the cell wall of grasses. The grass samples had higher digestibility because fiber is potentially digestible while lignin is totally indigestible. This relationship of higher crude protein from shrubs and higher digestibility from grass is typical. Thus, allowing ruminants to consume a combination of kochia and dormant grass is most desirable for obtaining a balance of nutrients and energy in the diet. Table 1. Nutritional auality of forage samples clipped from pastures forage kochia crested wheatgrass Crude protein % 7.2 5.9 NDF % 59.5 63.6 ADF % 47.3 42.5 IVTD % 52.1 55.8 Forage quality based on the clipped samples of both forage kochia and crested wheatgrass decreased as the winter progressed. Crude protein for the forage kochia was 10.7% in November and gradually decreased to 5.3% by the end of January (study termination). Additionally, crude protein for crested wheatgrass was 6.7% in November and dropped [0 5.1 % by late January. Reduction of forage quality as the grazing season progresses is to be expected for two reasons. First, cattle graze selectively and remove the best material first, leaving poorer quality material. Second, the forage continues to mature and weather throughout the winter, losing nutritional value in the process. The quality of cow diets was always higher than quality of the forage available to them (Table 2). As stated previously, this is to be expected because grazing livestock always select a diet that is higher in nutritional value than the average of all the forage available. Diet quality declined from November to January. This is also to be expected because the value of the forage that remains late in the grazing season is less than what was available in November. Despite the rather dramatic decline from November to January, January diets still had adequate crude protein to support ruminal digestion of forage (7% is considered the minimum crude protein that will support rumen fermentation). Additionally, diets that are 60% digestible should be adequate to meet requirements of nonlactating cows in mid- to-late gestation. This is supported by their ability to maintain body condition, even in January when the diet quality was its lowest.