Oklahoma City, OK

Photograph of the Dream House Motel Highway 77 South, 45th and Shields, in Oklahoma City, OK. Published by Pat Mildred Murphee, Dallas TX

Accuracy of Predicting Stages of Bovine Estrous Cycle by Gross Appearance of the Corpus Luteum

Four readily identifiable changes in appearance of corpora lutea (Stages I to IV) occur during a bovine estrous cycle. Accuracy of estimating the stage of an estrous cycle by appearance of corpora lutea was determined in a double-blind study. One investigator observed estrus in a group of heifers while another with no prior knowledge of reproductive histories of the heifers estimated stage of the estrous cycle by visual inspection of their corpora lutea. Stage of the estrous cycle (Stage I, days 1 to 4; Stage II, days 5 to 10; Stage III, days 11 to 17; Stage IV, days 18 to 20) was estimated correctly in 41 of 48 heifers. The correlation between estimated and actual days of the estrous cycle was .81. In addition, concentrations of progestins and weights of corpora lutea during estimated stages of the estrous cycle were similar to many other investigations. Stages of the estrous cycle in heifers can be estimated from appearance of corpora lutea

Genetic and Environmental Factors Affecting the Suitability of Dogs as Guide Dogs for the Blind

Many dogs are found to be unsuitable for training as guide dogs for the blind. Consequently the Royal Guide Dogs for the Blind Association of Australia has embarked on a breeding program to produce a strain of labrador dogs which is suitable for guide dog training. The most common reasons for rejecting dogs are fearfulness, dog distraction, excitability, health and physical reasons and hip dysplasia. The selection program seems to have been successful in improving the success rate mainly by lowering fearfulness, but there has not been a continuing improvement. This is probably due to continual introduction of dogs from other populations into the breeding program. Males suffer from a higher rejection rate due to dog distraction and a lower rejection rate due to fearfulness and excitability than females, so that there is little sex difference in overall success rate. The heritability of success (0.44) is high enough to predict further progress from selection, again mainly against fearfulness. Variation in environment prior to 6 weeks of age, in age when dogs were placed into a private home and in age when males were castrated, had little effect on the success rate