A total of 228 separate dung pats voided by lactating dairy cows between May and October on a ryegrass/dover sward were studied for 2 years. The pats were on grazed swards receiving, on average, either 440 or 110 lb N/ac (492 or 123 kg/ba) per year. The mean area of the pats was 0-62 ft" (0 058 m^) with no difference in area between the pats on the two N treatments. On average, the pats on the high-and the low-N treatments crumbled in 63 and 55 days, respectively, and disappeared in 115 and 113 days, respectively. Pats deposited in July disappeared significantly quicker than pats deposited in May. The average area of rejected herbage around the pats was 2-63 and 0 84 ft" (0 244 and 0 078 m^O, respectively, 1-2 months, and 1 year after they were voided; but after 2 years tbe affected areas were recolonized with ryegrass and clover and were grazed normally. It is concluded that the levels of N fertilizer applied had no differential effects on the breakdown of the dung and on the subsequent recolonization of the affected areas by pasture plants.

A study of the relationship hetween some farm and grassland management factors and milk production at the Hannah Dairy Research Institute in the period 1951-70 is reported. During this period various aspects of farm management were altered, and total annual milk production was increased from 28,400 to 63,900 gal. The major factors influencing total milk production, in order of declining importance, were: the overall rate of stocking, milk yield per cow, the numher of milking cows as a percentage of all animals, and the acreage of grass as a percentage of the total farm acreage. Stocking rate and milk yield per cow together explained 85% of the total variation in annual milk production. No significant relationship was found hetween total milk production and weight of concentrates fed/gal, the amount of fertilizer N applied/aCf rainfall and sunshine data. It is suggested that the lack of a direct relationship between milk prodnction and the amount of fertilizer N applied resulted from the contrihution of N from clover and from grazing animals.

A technique for the automatic recording of the grazing behaviour of dairy cows was investigated, using 'Vibracorders' which transmit grazing movement via a pendulum and stylus to a 24 h recording chart. The total labour input was 2 h/day for 6 cows, which gave 144 h of results. In 2 months, 3312 h of recording were obtained. Total grazing time per cow in 24 h was 559 min. on a rigid rotational system of grazing and 638 min. on a system of set stocking. Grazing time was significantly and negatively related to the yield of available herbage DM. It is concluded that if the Vibracorders are sealed and fitted correctly, they are simple, reliable and accurate instruments for automatically measuring the grazing behaviour of dairy cows.

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