1. The effects of restricting the daily grazing hours of indigenous cattle have been studied on grazing behaviour and cattle weights. The cattle grazed on natural veld.2. Three cattle-management treatments, i.e. free range, moderate kraaling (11 hr. grazing day) and severe kraaling (7 hr. grazing day), were compared during seasonal periods of low cattle-weight gains, large cattle-weight gains and large cattle-weight losses.

1. The normal pattern of grazing behaviour of free-range indigenous cattle under conditions of lenient stocking and overstocking has been studied throughout the year.2. There was a fairly fixed daily pattern of herd behaviour. The cattle usually started day grazing round sunrise and ceased approximately 1 hr. after sunset. There was a morning and afternoon peak of intense grazing activity separated by a rest period and watering about midday. There was usually one peak of night grazing.3. The average daily grazing times varied from 8 hr. during the rains period of relative feed abundance, to about 13 hr. during the dry season period of malnutrition.4. During the dry season there were no major differences in grazing times between the leniently stooked and overstocked groups. Both herds were losing weight.5. The relatively greater weight gains of the overstocked herd compared with the leniently stooked group during the rains resulted from the increased grazing times of the overstocked herd.6. The night grazing remained fairly constant at approximately 20% of the total daily grazing time.7. There were no seasonal effects on the pattern of grazing behaviour. High daytime temperatures did not cause an increase in the proportion of night grazing of indigenous cattle.

Three grass/legume pastures were evaluated under Northern Rhodesian conditions.A plot trial measured the herbage yields of Stylosanthes gracilis, velvet beans (Stizolobium deeringianum) and giant Rhodes grass (Chloris gayana) grown as pure stands, and in a mixed association with Rhodes grass. The herbage was harvested for 3 years, and the plots were then planted with a maize crop to test any residual effects.After the establishment year, the D.M. yields, and especially the C.P. yields of the legume and grass/legume treatments, were markedly superior to grass alone. The increased yield of the grass/legume mixtures was due to the net gain contributed by legume herbage. There was no evidence of an underground transference of N from the legume to the associated grass.Although there was no measurable treatment effect on soil N and C, the maize following the legume and grass/legume treatments had a higher leaf N level, and approximately double the yield, compared with the maize following the grass-alone treatments.There were no significant differences in cattle weight gains when Rhodes grass alone, Rhodes grass/Stylosanthes, Rhodes grass/velvet beans, and Rhodes grass/pigeon peas (Cajanus cajan) were utilized as hay and foggage in the dry season.Digestibility trials showed mature Rhodes grass hay to be a submaintenance feed, deficient in dietary protein. The addition of Stylosanthes raised the herbage digestible C.P. fourfold. The Rhodes grass/Stylosanthes hay was a maintenance feed.The N yield of the grass/legume mixtures, although low by temperate standards, was 2½ times the N yield of grass alone. The potential value of a tropical grass/legume pasture will depend on the efficiency of the legume to fix N.

Indigenous (Bos indicus) oxen fed ad lib. were used to measure the changes in the apparent digestibility of mature Hyparrhenia veld during the dry season, and also the apparent digestibility of late-cut veld hay and nitrogen-fertilized veld hay. The forages were those used in a field trial, and the present results complement previous work.1. Mature Hyparrhenia veld harvested at the end of the rains as veld hay or green forage, contains approximately 50% digestible o.m. and 0·6% digestible c.p. The low level of approx. 3% c.p. resulted in a low apparent c.p. digestibility and consequent protein deficiency.2. The nutritive value of the mature Hyparrhenia grassland as ‘standing hay’ progressively dropped to 38% digestible o.m. and negative c.p. digestibility by mid-dry-season in July.3. There was an accompanying decline in voluntary intake of forage from approximately 12 lb. d.m./1000 lb. animal/day at the end of the rains to 8 lb. d.m./1000 lb. animal/day in mid dry season.4. The seasonal drop in digestibility values is accentuated by the drop in dry-matter intake so that a diet of mature veld herbage in mid dry season is grossly deficient in both energy and protein.5. The feeding of supplementary protein or urea resulted in a 40–60% increase in the intake of mature Hyparrhenia forage. Urea and groundnut meal were of equal value in their effect on herbage intake at the level of feeding used in this trial.6. The main factor limiting the utilization of the mature Hyparrhenia veld appears to be a dietary protein deficiency. Increasing the dietary protein level, either by using nitrogen fertilizers to raise the herbage crude protein, per cent, or by supplementary feeding of protein or urea, not only relieved the dietary protein deficiency, but, due to the resultant increase in forage intake, also corrected the deficiency in dietary energy. The nutritive value of mature Hyparrhenia forage was thus raised from a submaintenance to a supra-maintenance level.

No abstract

Abstract. We studied the effects of five diverse non‐agricultural organic wastes on soil composition, grass yield and grass nitrogen use in a 3–year field experiment. The applied wastes were distillery pot ale, dairy salt whey, abattoir blood and gut contents, composted green waste (two annual applications each), and paper‐mill sludge (one annual application). With the exception of N immobilization in the paper‐mill sludge treatment, the wastes had no unfavourable effects on the soil. In the 2–year treatments, grass dry matter yields from the abattoir and distillery wastes (26.3 t ha−1) were larger than those from a NH4NO3 fertilizer treatment (24.3 t ha−1) and from the dairy waste (20.4 t ha−1) and composted waste (22.8 t ha−1). Yield and N recovery were impaired markedly after the single application of paper‐mill sludge, both in the year of application and in the following year. The results demonstrated clear differences in the ability of the applied wastes to provide crop‐available N. We conclude that in order to improve prediction of both the benefits and risks from waste recycling to land, more information should be gathered on soil/waste/crop interactions.

A description is given of a double change-over, grazing trial designed to test the value of Hyparrhenia veld grazing for milk production during the rains.Three feeds were offered to lactating cows, and the effects of qualitative differences between the feeds were measured on milk yields. The treatments were:

No abstract