The data from all published results of grazing trials in which three or more rates of stocking were compared for one or more years were examined. Where possible regression equations and correlation coefficients were calculated. In many cases, a significant negative correlation was found between stocking rate per acre and liveweight gain per animal per day. In no case was the relationship positive, and no point of discontinuity was found in the linear relationship. The slope of the line appeared to be related to the length of the grazing season; the longer the season, the steeper the slope. The application of these results in practice is discussed in agronomic and economic terms.The carrying capacity of a pasture or range is the number of animals of a specified type that can subsist on a unit area and produce at a required rate over a specified period, usually a season, a year, or longer.To achieve maximum output it is important that the carrying capacity of pastures should be known. This is not an easy thing to measure because of difficulties in measuring the quantity of available nutrients per unit of land. It is not an easy thing to achieve, even then, because of difficulties in utilizing what is available. These difficulties stem from an imbalance in the herbage of nutrients required by the animals and from poor sward structures from which animals are unable to obtain enough food.An optimum stocking rate is that which allows grazing animals to produce at the most economic rate. This rate may not be the maximum possible, as it depends on the economic relationship between the value of the pasture and the product, and the costs associated with the necessary grazing management. As the costs and values of these input and output factors vary from time to time and from place to place according to the laws of supply and demand, it would be of great assistance to producers of animal products to know approximately how production per animal and per acre is affected by the stocking rate per acre per grazing period.On all but annual pastures the effect of any previous grazing will be seen in the current productivity of the pasture and trials must be continued for several years in order to measure any efFects on animal production of pasture degradation due to overgrazing or understocking. Stocking rate has an effect on the quantity of herbage grown, the proportion eaten and the amount eaten by each animal. It has been shown by Mott (18) Riewe (20) and Cowlishaw (8) that the relationship between stocking rate and liveweight gain per acre is curvilinear. Riewe (20) and Cowlishaw (8) showed from their data that the relationship between stocking rate and liveweight gain per animal appeared to be linear. Harlan (10) suggested the use of a double exponential equation, but he calculated stocking rate ia terms of acres per animal. Using the reciprocal of this term (animals per acre) for his data also produces a straight line relationship (Riewe, 21).Petersen, Lucas and Mott (19) produced some equations based on a number of assumpti...

Factors affecting the grazing habits of ruminants are discussed in relation to the attractiveness and nutritive value of herbages and the observed preferences of cattle and sheep at different times.Methods of measuring stock preferences are considered and it is concluded that, while frequent eye estimates of the quantity of each species appear to provide an adequate method, continuous observations and herbage sampling are useful adjuncts to it.The results of five experiments are given. Four were carried out in 3 years' winter grazing and one on spring, summer and autumn grazing over 2 years. In the latter experiment herbage samples were chemically analysed and a relationship with the observed preferences was calculated.In the winter grazing trials the greener grasses tended to be selected first, i.e. timothy, white clover, rough-stalked meadow grass, perennial and Italian rye-grass. Cocksfoot, Phalaris, red fescue and meadow fescue were not generally relished. Meadow foxtail, smooth-stalked meadow grass, tall fescue and sometimes the different varieties of rye-grass and timothy varied in rank from year to year as a result of differential frost damage and fungal attacks.In the summer grazing trials lucerne and white clover were found palatable in all the 1956 trials; in 1957 lucerne remained so, but white clover was less well liked, especially in June and July. The amount of grass growing with the clover seemed to affect attractiveness, mixtures being preferred to either species by itself. Meadow fescue and timothy were always ranked high, perennial rye-grass and cocksfoot usually next. Agrostis and red fescue were lowest. For the grasses, preference rank was positively correlated in 1957 with water-soluble dry matter, water-soluble ash, water-soluble carbohydrate and negatively correlated with lignin content.Results are compared with those of other investigators and they show a marked degree of similarity. Variability in the data for sheep is possibly due to limitations in technique. The results for sheep and for cattle are compared; and it was generally found that cattle were fonder of meadow fescue than sheep, and less fond of cocksfoot.Stock appear to graze those plants which will most readily supply their requirements for salts and energy (carbohydrates). Factors like dung, fungal attack, accessibility, density and toughness may interfere with this relationship.

The treatments in this summer-grazing experiment were designed as a 3 x 3 factorial; 3 levels of nitrogenous fertilizer, supplying 0, 336 and 672 kg N/ha per annum, and 3 stocking rates. The fertilizer was applied in 6 to 8 dressings at intervals of 3 to 4 weeks. The animals used were fattening Hereford x Friesian steers. The stocking rates were calculated on the basis of data available on herbage production under N and irrigation treatments and varied according to the level of N input. The experiment was laid out in 6 randomized blocks, which were grazed in rotation. Blocks were removed from the grazing cycle in spring and early summer of each of the 3 years (1962-4) over which the experiment was conducted and cut for conservation; yields were recorded. Details are given of: grazing management; results of studies of soil-N levels; the quantities of herbage removed for conservation; the quantity, chemical and botanical composition of the herbage available for grazing; and herbage consumption.

Leaf protein concentrates were treated in various ways in an attempt to improve their nutritive value, as measured by the “gross protein value” technique with chicks. Washing with hot water improved the value of some lucerne concentrates by removing a water‐soluble toxic factor. No appreciable improvement was obtained by: (a) varying pH of precipitation of curd, (b) different methods of drying the wet curd, or (c) solvent extraction of pigments, waxes, etc. Dried whole juice and alkali‐soluble protein had low nutritive values. The leaf protein concentrates differ considerably in “gross protein value”, but all are inferior to the better animal protein concentrates.

In a 3 X 3 factorial experiment, the effects of three levels of nitrogenous fertilizer (0, 336 and 672 kg/N per ha) and three grazing intensities on live-weight gains and carcass attributes were measured. The live-weight gains of the animals (per head) over the season were greater at the low and moderate grazing intensities than at the high; this effect occurred mainly from July to October each year. Gains were low on the no-nitrogen swards from July 1962 to the end of the grazing season and throughout 1963: this was related to the very high clover content of the swards. In all years, as grazing intensities increased, the carcass weights per animal became lower. Carcass balance, carcass length, depth of longissimus dorsi muscle, fat thickness over the longissimus dorsi, weight of kidney suet and channel fat, and weight of the alimentary tract also reflected the effect of treatment on weight gains. The results are discussed in relation to the botanical composition and consumption of the herbage, presented in Part I.