Development of a Nutritional Model to Predict Digestible Energy Requirements of Broodmares based on Body Condition Changes
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Nutritional models have been developed for beef and dairy cattle to estimate energy balance based on changes in body condition score. These models have not been developed or fully evaluated in horses to date. The objective of this study was to develop a model to predict changes in body weight (BW), rump fat (RF) thickness, and overall % body fat (BF) to maximize profitability and productivity by accurately predicting energy balance of mares. The evaluation of the model was performed using non-lactating Quarter Horse mares (n=20; 4 to 18 yr of age). The initial BW ranged from 376 to 553 kg, with an initial body condition score (BCS) of 3.5 to 7.0 (scale of 1 - 9; 1 = emaciated, 5 = moderate, and 9 = obese). The BCS, RF thickness, and BW were measured for each mare prior to the commencement of the feeding trial and once/wk thereafter for the duration of a 30 d feeding trial. The pre-trial BCS was used to assign mares to 1 of 4 treatment groups and fed to alter BCS by 1 unit as follows: Group 1, 4 up to 5; Group 2, 5 down to 4; Group 3, 6 up to 7; and Group 4, 7 down to 6. Initial BCS, target BCS, %BF, and BW data was collected from each mare and input into the model. Mares were individually fed according to the DE suggestions proposed by the model in order to achieve the targeted BCS change within 30 d. Results showed a 79.8% correlation between BCS and BF in which for every change in 1 BCS (either increasing or decreasing) a change in the same direction of 1.054 percentage units of BF can be expected. All mares' observed final %BF values finished with less than a 20% variation from the model-predicted values, less than 10% variation from BCS values, and less than 32kg variation from final EBW values. An equine nutritional model will enhance feeding management and also reduce the costs of unnecessary over-feeding while maintaining broodmares at a nutritional level to achieve optimum reproductive efficiency.
Cordero, Viviana 1986- (2011). Development of a Nutritional Model to Predict Digestible Energy Requirements of Broodmares based on Body Condition Changes. Master's thesis, Texas A & M University. Available electronically from