Influence of Mare Body Composition on Colostrum Quality

Twenty-two Quarter Horse mares, fed 100% NRC recommendations, and their offspring were used to evaluate various body composition measurements as indicators of colostrum quality. Starting 45 d pre-partum mares were evaluated weekly using the Body Condition Score system, ultrasonic measurements of rump fat, rib fat, loin area and intramuscular fat, and Westervelt’s equation to determine percent body fat. Post parturition colostrum samples were collected by hand at 0, 6, 12, 24 and 36 h postpartum and evaluated for protein, fat, lactose, somatic cell count, urea nitrogen, acetone, total solids, non-fat solids, IgG, IgA and IgM. Foal blood was collected via jugular venipuncture at 0, 12 and 24 h post-partum to determine the failure or success of passive transfer. Colostrum composition at 0 h was similar to previous research. Immunoglobulin isotype concentrations at 0 h were lower than previous research. Data from 6, 12, 24, and 36 h provide further insight regarding the rapid change from colostrum to mature milk, as there is significant change from 0 to 12 h (P˂0.0001). While no single measurement provided consistent correlations to colostrum quality or composition, the trend was that fatter horses produced less protein and non-fat solids, and more lactose and fat. Furthermore, the combination of rib eye area at the 13th/14th ribs, fat at the 13th/14th ribs and rump fat was found to be the best indicator for body condition and/or overall fatness (P˂ 0.001; R2=0.80145)