Silage and milk production: a comparison between four rates of groundnut cake supplementation of silage of high digestibility

Grass silage made in late May from S24 perennial ryegrass was offered to twelve Ayrshire cows in a 16-week feeding experiment. The silage had a DM content of 25.3%, a pH of 3.91, and contained 16.8% CP and 68.4% digestible organic matter in the DM. The silage was fed ad libitum and was the sole feed in the control treatment. In the other three treatments the silage was supplemented with a cube offered at rates of 0.8, 1.4 and 2.0 kg per 10 kg milk. The cube contained 82.2% groundnut, plus molasses and minerals, and had 37.9% CP in the DM. The daily intake of silage DM was 11.4 kg per cow on average over the four treatments which did not differ significantly. The mean daily milk yields were 14.8 kg per cow in the control treatment, and 16.5, 18.2 and 18.4 kg in the 0.8, 1.4 and 2.0 kg supplement treatments respectively. The SNF, CP and lactose contents of the milk were Wghest on the 1.4 kg supplement treatment. It is concluded that with a high digestibility silage, there is little evidence to support the feeding of more than 1.4 kg of high-protein cubes per 10 kg milk in the declining phase of lactation.     

A COMPARISON OF TWO HAYS FOR BEEF PRODUCTION

A medium quality barn-dried hay and a poor quality field-cured hay were each supplemented with 3 levels of concentrate in the diet of young beef cattle, averaging 313 kg liveweight. The supplement was given on predetermined hay concentrate metabolizable energy (ME) ratios based on the determined ME of the hays and an assumed ME of 3·0 McalsAg DM for the supplement. The hay concentrate ratios used were 1:1, 1:2 and 1:3, the aim being to provide a reasonable rate of growth (0·7 kg/day) with the poorer hay. It was necessary to include urea in the concentrate mixtures used on the 1:1 and 1:2 ratios with the field-cured hay. The urea appeared to have an adverse effect on the intake and utilization of DM on the 1:1 ratio. The range of mean intakes of supplement DM was 3·02 to 4·41 kg/day for the barn-dried hay and 2·23 to 4·61 for the field-cured hay. Mean daily liveweight gains with the barn-dried hay were 0·76, 0·89 and 0·85 kg for the 1:1, 1:2 and 1:3 ratios, respectively, with no significant difference between ratios. The mean daily gains with the field-cured hay were 0·39, 0·77 and 0·75 for the three ratios, the mean gain on the 1:1 ratio being significantly lower than those of the other ratios. The ME conversion ratios were not significantly affected by either ratios or hay type, except on the 1:1 ratio with field-cured hay. There were significant differences between the barn-dried hay and field-cured hay diets in the digestibilities of DM, organic matter, crude protein and energy; the mean coefficients for DM being 74·5% and 65·6%, respectively.     

Studies on the ecology of actinomycetes in soil—VIII: Distribution and characteristics of acidophilic actinomycetes

Acidophilic actinomycetes, growing between pH 3.5 and 6.5, were isolated from 17 natural soils and mine wastes. Most isolates were Streptomyces spp. and selected ones were compared with some established neutrophilic species by assessment of overall similarity. Acidophilic and neutrophilic strains clustered separately, differing in a number of cultural and physiological characters, in addition to pH requirements. The possible importance of acidophilic actinomycetes in soil is discussed.     

Sorption of phosphate by aluminium and iron(iii)-hydroxy species on mica surfaces

Freshly cleaved mica sheets with aluminium- or iron(III)-hydroxy species on the cationexchange surface were prepared by suitable treatment with AlCl₃ or FeCl₃. These surfaces were considered as model soilk mineral surfaces and their interaction with phosphate studied using techniques previously developed for the study of single planar surfaces.Adsorption isotherms for both the iron(III) and aluminium systems were very similar and could be interpreted as two Freundlich isotherms indicating two different adsorption processes, one operating below a solution concentration of 10^?5 M and thee other above. Results obtained from the continuous monitoring of adsorption indicate that a rearrangement of adsorbed phosphate occurs with time on both the aluminium- and iron(III)hydroxy surfaces. This rearrangement reduces the rate of desorption and could be a cause of phosphate fixation in soils.