Facial expressivity in dominant macaques is linked to group cohesion.

Social living affords primates (including humans) many benefits. Communication has been proposed to be the key mechanism used to bond social connections, which could explain why primates have evolved such expressive faces. We assessed whether the facial expressivity of the dominant male (quantified from the coding of anatomically based facial movement) was related to social network properties (based on social proximity and grooming) in nine groups of captive rhesus macaques (Macaca mulatta) housed in uniform physical and social environments. More facially expressive dominant male macaques were more socially connected and had more cohesive social groups. These findings show that inter-individual differences in facial expressivity are related to differential social outcomes at both an individual and group level. More expressive individuals occupy more beneficial social positions, which could help explain the selection for complex facial communication in primates.

Metabolic responses of chronically starved horses to refeeding with three isoenergetic diets.

OBJECTIVE: To examine metabolic responses of chronically starved horses to refeeding with 3 isoenergetic diets. DESIGN: Uncontrolled clinical trial. ANIMALS: 22 mature mixed-breed horses that were emaciated but otherwise clinically normal. PROCEDURE: Horses were fed 1 of 3 diets: alfalfa hay, oat hay, or a combination diet of half oat hay and half commercially prepared ration. Digestible energy of diets was gradually increased throughout the refeeding period. One pre- and 4 postprandial blood samples were obtained daily, and analyses included RBC count, Hct, and determination of hemoglobin, glucose, insulin, free fatty acid, total bilirubin, 2,3-diphosphoglyceric acid, phosphorus, magnesium, calcium, sodium, and potassium concentrations. Body weight, fecal output, and feed and water consumption were measured and recorded daily. Repeated-measures ANOVA was used to examine dietary and temporal (day) effects of the 3 dietary regimens during 10-day trials. RESULTS: 19 Horses survived. Three horses (2 fed alfalfa diet, 1 fed combination diet) died of metabolic or gastrointestinal problems. Increasing temporal effects in serum concentrations of glucose, insulin, magnesium, calcium, and sodium; decreasing temporal effects in serum concentrations of free fatty acid, 2,3-diphosphoglyceric acid, and phosphorus; and dietary effects in serum concentrations of glucose, insulin, magnesium, and potassium were detected in the 19 surviving horses. Serum phosphorus and free fatty acid concentrations decreased dramatically during the first 5 days of refeeding with all 3 diets. Serum magnesium concentrations increased in horses fed the alfalfa hay diet, whereas improvement was not evident in horses fed oat hay or combination diets. Horses receiving the alfalfa and oat hay diets had lower postprandial glucose and insulin concentrations than horses receiving the combination diet. Horses fed oat hay alone ate 92% of feed offered, compared with 98% feed consumption for horses fed alfalfa hay or combination diets. CLINICAL IMPLICATIONS: Clinically normal emaciated horses can be successfully rehabilitated by gradual refeeding with a high forage diet.

Protozoal myeloencephalitis in horses in California.

Three cases of equine protozoal myeloencephalitis were diagnosed over a 12-month period in horses that had never left the state of California. These cases suggest that the disease is enzootic in California.