The intra-seasonal changes in the nutritive value of pasture herbage.

Data are herein reported upon the intra-seasonal changes in the nutritive value of a mixed herbage consisting of Kentucky blue grass, red top and wild wb1te clover as shown by growth and digestibility studies with young rabbits. A progressive decline in nutritive value and digestibility until midsummer and a complete recovery in all respects in the fall was noted. These data would indicate that marked differences in nutritive value may exist between herbage representing only ten days growth when taken at different parts of the season. The effect of small increases in lignin upon the digestibility of the various food fractions would indicate that it is not only the amount, but also the mode of deposition of the lignin which determines its effects upon digestibility and nutritive value. The effect of unfavourable growing conditions or approaching maturity would seem to be intimately related to these changes in lignin content