干旱区生态环境知识资源中心

Fecal microhistology was used to estimate botanical composition of samples taken from Hereford (N = 11), Angus (N = 11) and Brangus (N = 37) 3 to 5 year-old cows in 3 seasons (October, 1991 and January and July, 1992) and from Hereford (N = 10), Angus (N = 9) and Brangus (N = 34) calves in October, Breed differences in botanical composition of diets and relationships between dam and offspring botanical composition of diets were examined, Breed differences were observed for cows in all 3 seasons and for calves in October, Brangus cows showed greater preference (P <0.05) for Sporobolus than Hereford cows in October, January, and July, Brangus cows also showed greater preference for Sporobolus than Angus cows in January and July, Brangus and Angus calves showed greater preference for Sporobolus than Hereford calves in October (P < 0.05), Brangus cows had a stronger preference for Yucca and total shrubs in January than either Hereford or Angus cows, Hereford cows and calves had stronger preference for Aristida than either Angus or Brangus in October (P < 0.05), Regression of October calf botanical components on dam botanical components indicated significant relationships for only 2 genera, Aristida (P < 0.01) and Sporobolus (P < 0.06). These data suggest that genetic composition of the animal is an important factor determining utilization of key plant species on Chihuahuan desert ranges.