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CIRCULAR 870, U. S. DEPARTMENT OF AGRICULTURE 



be expected for a few weeks each winter. Hence new green forage is 

 uncertain and not adequate to maintain cattle weights during this entire 

 fall and winter period. 



The second period starts by late winter, usually about February 1. 

 At this time the green forage becomes adequate to maintain cattle 

 weights for the remainder of the winter, even though temperatures are 

 still too low for rapid plant growth. During the first early spring weather, 

 when mean temperatures for most days of the week are near 50° F. or 

 above and frosts are infrequent, plant growth is accelerated and green 

 forage begins to grow faster than it is grazed. Later in the spring, 

 usually in April, the temperature rises rapidly and there is a surge of 

 plant growth. Ordinarily most of the plants mature and dry early in 

 May, but a limited amount of herbage remains green for a short time 

 longer. 



SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. 



Figure 4. — Relation of the three yearty plant-growth periods to monthly precipitation 

 and mean air temperature, San Joaquin Experimental Range (average 14 years, 

 September 1934-August 1948). 



By early summer the third period has begun. This is usually in June, 

 when almost all of the plants have dried. The little remaining green 

 leafage is on scattered plants of summer-growing annual species, or 

 perennial bunchgrasses. Most of the cattle forage is dry herbage until 

 fall rains bring new plant growth. 



UNCERTAIN GREEN FORAGE IN FALL AND WINTER 



The forage preference of cattle shifts from dry grass to the new green 

 plants soon after the seedlings emerge. The new plants are selected 

 when barely one-half inch in height, but cattle are forced to take some 

 old dry roughage as they search for the short new growth. This green 



