A simple instrument for estimating the yield of herbage from measurements of height has been tested in cutting and grazing experiments. The instrument consists of a verticle graduated shaft and two linked aluminium discs which settle on the herbage. The height of the discs from the ground is recorded. Highly significant relationships were established between the yield and the height of herbage. Linear regressions explained 80–90% of the variation in the cutting experiments, and 39–62% in the grazing experiments. The errors attached to the estimated yields were high, but, because of the simple construction, low cost and rapid operation of the instrument, it is concluded that it has many useful functions in grassland research and management.

Two grass sUages made in June and two made in September, all from the same field, were compared in a 16-week winter-feeding experiment with 12 Ayrshire cows. The silages were fed ad lib. with a supplement of barley and groundnut eake. One of the sUages made in June and one made in September had been treated with \ gallon of formie acid per ton of herbage when cut, whereas the other two silages were untreated. The contents of digestible organic matter in the sQage DM made with and without the acid additive were 67-4 and 63-8%, respectively, in the June silage, and 66-1 and 62-7% in the September sUage. The intakes of silage and total DM were higher in the treatments containing the acid-treated silages than in those containing the untreated sflages. The mean daily milk yields from cows fed on the sUages made with and without the additive were 36-3 and 33-8 lb (16-5 and 15-3 kg), respectively, for sflages made in June, and 35-4 and 34-1 lb (16-0 and 15-5 kg) for those made in September. The solids-not-fat (S.N.F.) contents of the milk averaged 8-60 and 8-50% respectively, from the silages with and without the additive. It is concluded that the silage with the formic-acid additive was superior to the untreated silage as a feed for dairy cows.

The intake of drinking water of lactating British Friesian cows in 14 herds with a total of 840 animals was measured monthly from November to April inclusive. The intake of food, the air temperature and relative humidity were also recorded. The herds which mainly contained autumn-calved cows were managed under controlled commercial conditions. The average daily intake of drinking water was 49-9 (range 20-1 to 87-1) kg/cow for animals yielding an average of 16-8 kg milk/day in an environment with a mean temperature of 8-2°C and a relative humidity of 84-8 %. The amount of water drunk daily was positively and significantly related to the mean daily milk yield and the drymatter content of the ration, but not significantly related to either the mean air temperature or the relative humidity. The average intake of water was 3*70 kg per kg of dry matter consumed after subtracting the amount of water in the milk. On average, 40-0% of the total daily intake of water was drunk between 15-00 and 21*00 hr. Behaviour studies of 24 hr duration on five herds showed that drinking time ranged from 2-0 to 7-8 min/cow per day, and the rate of drinking varied from 4-5 to 14-9 kg/min. Recommendations are made for the provision of drinking water for dairy cows being offered a wide range of forages under modern conditions of housing.

Three grass silages of different chop lengths made from a uniform sward of S23 perennial ryegrass were compared in four experiments including a feeding experiment with twelve lactating cows, an eating behaviour study, a rate of passage investigation and a selection trial. The silages had median chop lengths of 9-4. 17-4 and 720 mm, termed short, medium and long, with pH values of 3-93, 3-94 and 417 and D-values of 659, 65-2 and 64 4 respectively.The daily intakes of silage DM and the daily milk yields increased as silage chop length decreased. The milk yield response to shorter chopping was significant with a supplement of groundnut but not significant with a supplement of sugar-beet pulp. Chop length had small and generally non-significant effects on milk composition.Eating and ruminating times expressed as min per kg DM decreased as silage chop length decreased but the retention time ofthe silage residues in the entire digestive tract was not significantly affected by chop length. When offered simultaneously, the intakes of the individual silages were 52 2, 319 and 15 9% ofthe total DM intake for the short, medium and long treatments respectively.Although silage with a chop length of 9 mm had nutritional advantages over longer silages, it is concluded that the mechanical and economic aspects of silage making must be considered fully when defining optimum chop length.

No abstract