H.—29,

Regular observations have been made on the occurrence of mastitis in two experimental herds. General field observations have been made on the occurrence of the disease in the Waikato. The mastitiscontrol scheme which has been operating in that district during the past eight years has been criticallyreviewed during this year and it is considered that this scheme will need considerable revision before it can be applied generally. It is hoped to start work in an experimental herd next year with a view to exploring the possibility of devising a more efficient control scheme. A special bacteriological study has been continued with a view to determining the types of organisms responsible for mastitis in New Zealand. Preliminary work has been done to establish a technique for studying the effect of nonstripping. " Orass Staggers "in Dairy Cows.—A study has been made of the seasonal variations of magnesium in the blood of cows at Ruakura, Massey Agricultural College, and Wallaceville. The effect of various pasture species and of pasture management and of the administration of magnesium compounds on the blood magnesium status has also been studied. Hematological examination of field cases have been made, and these have indicated that the disease is distinct from one which it resembles clinically in Australia. " Rye-grass Staggers " in Sheep and Cattle. —Some biochemical studies have been made and feeding experiments have been conducted with pasture collected from affected paddocks. Sterility. —The investigations connected with the diagnosis of bull sterility by semen examinations have been continued. The Technical Officer of the Dairy Board has collaborated in making a critical examination of the results of this year's work. Should the result of this indicate that the method is of sufficient value, a service to dairy-farmers will be initiated whereby it may be made available generally. The experiments designed to study the effect of high protein rations on bull sterility have been continued. There is so far no indication that any dairy pastures usually grazed by bulls in New Zealand are sufficiently high in proteins to cause sterility. The experiments to investigate the effect of protein on sterility in male rats have been continued and some interesting results are being obtained. With a view to determining the effect of nutrition on dairy-cow sterility, regular pasture observations have been made on a number of dairy-farms throughout the year. During the next season the herdtesting branch of the Dairy Board will collaborate in this work. Artificial Insemination. —A second year's work has been done on eleven dairy farms; the results indicate that before artificial insemination could be widely used in New Zealand further information is required concerning technique, It is intended to use artificial insemination entirely on one experimental herd next season, and it is hoped by this means that valuable data will be obtained. Contagious Abortion. —The first calves were inoculated this year in an experiment designed to test the value of calf vaccination in preventing this disease. The project is a long-term one and the work will be continued over several years. Pig Nutrition.—Experiments have demonstrated the beneficial effect of feeding sows for six weeks after weaning on the number of the next litter and the beneficial effect of feeding for six weeeks before farrowing on the size of individuals in the litter. The effect of restricted feeding in reducing the thickness of back fat in baconers has been demonstrated, and co-operative experiments on a number of farms have confirmed these results. Experiments have shown that, at the present prices, root crops fed during the winter to store pigs return a profit representing from £40 to £140 per acre of root crops. Dairy-cow Nutrition. —Experiments have been commenced to determine the best methods of managing and supplementing pastures for dairy cows. The initial results indicate that proper pasture management can materially ameliorate the shortage of feed in the winter. Chilled-beef Production. —Encouraging results have been obtained in experiments designed to determine if chilled beef can be profitably produced on Waikato sheep-farms. Curd Feeding to Poultry. —Experiments indicate that the feeding of curd from skimmed milk to poultry is at least as profitable as feeding skimmed milk to pigs. Pasture Research.—A number of projects have been conducted in collaboration with the Fields Division, and some of these will doubtless be reported more fully by the Director of that Division. Feed Flavour.- Experiments have indicated that feed flavour caused by clovery pastures in spring can be controlled by pasture management and special grazing practices. Rate of Growth of Pasture.—This has been measured at Ruakura and Karamu throughout the year, and it has been found that half the total production takes place from October to December, while rather less than one-tenth of the total production takes place from April to June. This emphasizes the very real necessity for special management and supplementing of pasture to increase winter feed. Ragwort.—Experiments have been continued to determine the best time of the year at which to apply sodium chlorate. Cobalt Deficiency.—Experiments at Mamaku have indicated that bush sickness can be completely controlled by annual top-dressing with small amounts of cobalt. It is hoped to produce this year the third generation of sheep on cobalt-deficient paddocks which have been treated in this way. Attention is drawn to a statement in the report of the Superintendent, Ruakura Animal Research Station, that the Mamaku Plateau offers definite possibilities for sheep-farming, if the clearing, stumping, ploughing, and resowing of grass of the abandoned farms were undertaken. The duration of the effect of larger dressings of cobalt is being studied, and the results indicate the possibility of these larger dressings being used successfully at longer intervals on hill pastures. Tests have been made to discover the effect of administering large doses of cobalt at monthly intervals,

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