Statistical research on the fate of water in the adult cow. II. The lactating cow

Abstract

SUMMARYStatistical tests were made on the data obtained from 100 non-pregnant lactating cows, whose milk production ranged from 4 to 22 kg/day. The cows were kept in metabolism stalls and fed 37 different rations.The authors have studied the correlation between total water intake, faecal and urinary water losses, absorbed and available water and the numerous other factors which were analysed in each of the 37 rations.Total water intake is closely related to the dry-matter intake and the dry-matter content of the diet; it is related also to the composition of the ingested dry matter but is unrelated to the daily milk production.Faecal water losses are closely related to the dry-matter intake and the dry-matter content of the diet; increase of pentosans and crude-fibre intake enhances the losses.Urinary water excretion is related to the amount of absorbed water and to the dry-matter content of the diet; a highly significant correlation exists also between urinary water and urinary nitrogen and potassium. Daily milk production and urinary water are negatively correlated.Water secretion in the milk depends on the dry-matter intake and on its composition; but there is no significant correlation between total water intake and milk water.