H—29

type. On the " controlled-grazing " farm the herd has been composed of well-reared two-year-olds ; on the " uncontrolled" farm, of poorly reared two-year-olds. The results obtained indicate the differences that might be expected: —

Live-weights

Production Averages

The production difference in favour of the controlled group is likely to be greater by the time the season is complete, due to a tendency for the heifers of the uncontrolled group to dry off earlier. The experiments in progress with cows under carefully controlled nutritive conditionson pasture involving large differences in the level of feeding provided an opportunity for building up both base-line information on the blood status (acetone bodies, sugar/ calcium, magnesium, and phosphorus) of New Zealand dairy cattle and information on the possible effects of differential nutrition on such characteristics. These characteristicsare of possible significance in relation to diseases associated with parturition and lactation (ketosis, grass staggers, and milk-fever). Blood samples were taken weekly for a month before and a month after calving ; thereafter they were taken monthly. Urine samples were taken monthly for acetone estimations. Results have not yet been fully examined. Nutrition of Coivs: Winter Feeding.—An experiment has been commenced to determine the effect of different levels of feeding during the winter on the subsequent lactation. Measurement of Digestibility of Cow Pastures.—The great practical difficulty of obtaining information of any value as to digestibility, nutritive value, and intake of dairy-cow pastures which arises from the fact that a digestibility trial involves a fourteenday feeding period, during which time any pasture is changing in character, while in practice the dairy herds graze a field in one to two days, has made it necessary to investigate possible modifications of existing methods. The great quantity of feed required to be cut and hand-fed to cattle in digestibility work is also a major difficulty for many reasons. Accordingly, work during the past year has been concentrated upon the possibility of using the sheep instead of the cow as the measuring animal, and dried

32

(From March, 1945, to twenty-four weeks after calving) Treatment. March. Precalving. Postcalving. Four Weeks. Eight Weeks. Twelve Weeks. • Sixteen Weeks. Twenty Weeks. Twentyfour Weeks. " Controlled " (19 head) "Uncontrolled" (18 head) Difference lb. 770 634 lb. 870 704 lb. 771 615 lb. 765 610 lb. 764 624 lb. 787 658 lb. 813 691 lb. 831 710 lb. 838 721 136 166 156 155 140 129 122 121 117

(Up to 17th March) Treatment. Milk. Test. Fat. Days. Number of Cows. " Controlled " " Uncontrolled " .. lb. 4,281 3,726 Per Cent. 5-4 5-3 lb. 233 199 216 216 19 18 Difference 555 01 34