Factors affecting water balance and fecal moisture content in suckling calves given dry feed

Holstein bull calves were used to examine factors affecting water balance and fecal moisture content in suckling calves given dry feed for 2 wk from 1 wk of age. In Experiment 1 (n = 16), the shift of water balance (decreased urine volume, and increased water retention and fecal water excretion) and elevation of fecal moisture content were greatest when calf starter and Sudangrass hay were fed in addition to liquid milk replacer, compared with calves receiving only milk replacer. Intermediate changes occurred when calves were fed milk replacer and calf starter or milk replacer, calf starter, and rice straw. Water retention was correlated positively with digestible DMI and negatively with urine volume. Fecal water excretion was highly correlated with fecal DM excretion. In Experiment 2 (n = 18), water balance and fecal moisture content during wk 2 were affected by free access to calf starter and hay from wk 1. Urine volume of calves fed dry feed and milk replacer was lower than that of calves fed only milk replacer; however, when water was available in addition to dry feed, urine volume was similar to that of calves fed only milk replacer. Fecal water excretion was highly correlated with water retention rather than with fecal DM excretion, suggesting a close relationship to extracellular fluid volume. Ruminal fermentation would be an important factor affecting both water balance and fecal moisture content in suckling calves given dry feed.