An electronic health system configured to determine an animal's ability to tolerate increased metabolic stress for the purpose of increasing weight gain by considering physiological responses to stress using auscultation analysis, said electronic health system comprising: electronic stethoscope means for conducting auscultations on the animal; and processing means configured to record and analyse auscultation sounds obtained from the animal by the electronic stethoscope means; the processing means being configured to: record heart and respiration rates of an animal during exposure to a controlled environment known to induce sympathetic adrenergic stress reactions; determine a cardiopulmonary rate ratio for the animal expressed as the heart rate divided by the respiration rate; determine a range of ratios for a plurality of animals within an observed population of animals; wherein the processing means is further configured to: determine a group of first values for ratios indicating respiratory compensating responses (CPR-R); determine a group of second values for ratios indicating cardiac compensating responses (CPR-C); determine a group of third values for ratios indicating normal compensating responses (CPR-N); and determine a likelihood an animal will develop a disease taking into account said ratios within said first, second, or third groups of values. electronic stethoscope means for conducting auscultations on the animal; and processing means configured to record and analyse auscultation sounds obtained from the animal by the electronic stethoscope means; the processing means being configured to: record heart and respiration rates of an animal during exposure to a controlled environment known to induce sympathetic adrenergic stress reactions; determine a cardiopulmonary rate ratio for the animal expressed as the heart rate divided by the respiration rate; determine a range of ratios for a plurality of animals within an observed population of animals; record heart and respiration rates of an animal during exposure to a controlled environment known to induce sympathetic adrenergic stress reactions; determine a cardiopulmonary rate ratio for the animal expressed as the heart rate divided by the respiration rate; determine a range of ratios for a plurality of animals within an observed population of animals; wherein the processing means is further configured to: determine a group of first values for ratios indicating respiratory compensating responses (CPR-R); determine a group of second values for ratios indicating cardiac compensating responses (CPR-C); determine a group of third values for ratios indicating normal compensating responses (CPR-N); and determine a likelihood an animal will develop a disease taking into account said ratios within said first, second, or third groups of values. determine a group of first values for ratios indicating respiratory compensating responses (CPR-R); determine a group of second values for ratios indicating cardiac compensating responses (CPR-C); determine a group of third values for ratios indicating normal compensating responses (CPR-N); and determine a likelihood an animal will develop a disease taking into account said ratios within said first, second, or third groups of values.