ALBERT

Description: 1. An experiment with dairy cows is described in which the production per animal and per acre obtained in three methods of grazing management were compared during 2 years.(A) An intensive method. Strip-grazing daily on heavily fertilized grass sward.(B) A modified intensive method. Continuous, free-range grazing on a heavily fertilized grass sward.(C) An extensive method. Continuous, free-range grazing on a grass and clover sward receiving a basic application of phosphate and potash only.The intensively fertilized swards received a total of 212 lb. fertilizer nitrogen per acre, together with adequate amounts of phosphate and potash throughout the grazing season. No supplementary foods of concentrate type were fed to the cows during the experiment.2. For the comparison of production per animal 3 × 3 Latin-square experimental design, with twelve Ayrshire cows and periods of 3 weeks' duration, was used. Two separate trials were conducted during the grazing season of 1955 and a third trial during 1956.3. The different methods of grazing management and intensive use of fertilizer had little influence on the milk yield and butterfat percentage of the milk of the cows.

Description: 1. The results are reported of three experiments in which metabolism trials were carried out with milking cows given artificial diets low in magnesium with or without supplementary magnesium.2. In Exps. 1 and 2, the basal diets provided cither about 13 or about 9 g. of magnesium/day, that is an intake of magnesium similar to that found previously with cut-grass diets (Rook & Balch, 1958) which produced hypomagnesaemia. The ‘availability’ of the magnesium of the artificial diets was, however, of the order of 25–35 % and higher than that of cut-grass diets, and for all cows the artificial diets provided magnesium in excess of requirements, as indicated by the excretion of measurable amounts of magnesium in the urine and the maintenance of normal concentrations of magnesium in the blood serum.

Description: 1. The ‘availability’ of the magnesium of diets consisting solely of roughage or succulent feeds, including herbages cut at different seasons and at different stages of growth, and of diets of hay supplemented with various concentrate feeds, was assessed in metabolism trials conducted with two non-pregnant, non-lactating Shorthorn cows.2. The highest daily intakes of magnesium (1720 g./day) were provided by a diet of red clover: grasses and hays generally gave a considerably lower intake of magnesium (8–10 g./day), and most of the other diets provided intermediate amounts. However, with timothy hay and barley straw, intakes of 5 and 2 g./day, respectively, were recorded. Supplements to a diet of hay of dairy cubes or of oilcakes rich in protein gave a massive increase in magnesium intake but a supplement of flaked maize provided little additional magnesium.3. The ‘availability’ of the magnesium of the diets was generally low, within the range of 5–30%. With diets of single feeds no clear distinction between the various roughages and succulents in the ‘availability’ of their magnesium was established, though within the group of herbages the lowest values tended to occur with grasses cut at an early stage of growth and the highest values at the mature stage. A supplement of flaked maize increased the ‘availability’ of dietary magnesium and one of protein-rich oil cakes decreased the ‘availability’ of dietary magnesium.4. The results are discussed in relation to the development of hypomagnesaemia in cattle grazing spring pasture.

Description: SUMMARYIn three experiments high quality, autumn-harvested dried Italian ryegrass and lucerne in the form of cobs and pellets and in one of these experiments in the chopped form were offered to mature castrated male sheep at a maintenance level of feeding. Only small differences were found between the physical forms of forage in digestibility of organic matter, retention of nitrogen and loss of energy in the urine, but the digestibility of crude fibre and the mean retention time of stained feed in the gut decreased with decreasing particle size. Increasing the level of feeding of cobs and of pellets from 800 g daily by three equal increments of 400 g caused a linear decline in digestibility but no difference was found between cobs and pellets in the rate of decline of digestibility. In three experiments the dried forages were offered ad libitum and in a fourth experiment a wide range of particle size was simulated by offering ad libitum five ratios of chopped and pelleted grass. Voluntary intake tended to increase as the particle size was reduced over the whole range, but there was no significant difference between the voluntary intakes of mixtures with a modulus of fineness of 4·4 or less. No difference was detected between the voluntary intake of cobs and pellets.

Description: SUMMARYFour hay-fed cows were used to study the effects on chewing behaviour of daily supplements of 3 kg whole barley grains, 3 kg whole oat grains or 2·2 kg rolled oats. Both whole grains increased the total time spent chewing by a similar small extent, probably due to a direct physical effect of the grain. The quantity of whole oat grains voided in faeces was lower than that of barley and it is concluded that the quality of chewing is more important than duration in breaking grains and ensuring their subsequent digestion.

Description: In recent investigations at this Institute, attempts have been made to devise for dairy cows a ration extremely low in magnesium to be used in fundamental studies of magnesium metabolism. All common farm roughages are moderately rich in magnesium, and wood pulp, which is low in this element, has been tested as a roughage for use in these experimental rations. American workers (Titus, 1926; Mead & Goss, 1935; Byers, Stanbus, Nelson, Brown, Davis & Gardiner, 1955; Matrone, Ramsey & Wise, 1957; Smith, McLaren, Anderson, Welch & Campbell, 1957; Ellis & Pfander, 1958; Williams, Musgrave, Schul & MacVicar, 1958) have previously used wood pulp as a substitute for roughage in the development of purified rations for cattle and sheep, and it was fed extensively as a substitute farm feedingstuff in Norway during the war years (1940–44)(Edin, Helleday & Nordfelt, 1941; Hvidsten, 1946). This note records some observations on the feeding of wood pulp, often as the sole roughage, to both dry and milking cows.

Description: SummaryA series of digestibility trials was conducted with non-lactating cows and adult castrated male sheep given diets of hay and dried or high-moisture maize grain in various physical forms. Sheep were able to digest all forms of maize well and to a greater extent than cows. In cows considerable variation in digestibility of maize was associated with the particle size of the maize and the individual animal. Maximum digestibility of dried maize in cows ensued when the modulus of fineness lay within the range 4·7–3·0 and with high moisture maize from 5·4 to 5·1. A study was made of the effect of particle size on the rate of digestion of maize suspended in nylon bags in the rumen. Evidence was presented showing the importance of rumination in ensuring the digestion of intact kernels. Possible causes of differences between cows in their ability to digest intact maize kernels are discussed.

Description: 1. Ammoniated sugar-beet pulp has been compared with decorticated ground-nut meal, when added to a control diet low in protein, in feeding trials with seventy-five cows on three farms and in a balance experiment with four cows.2. In the feeding trial the cows receiving decorticated ground-nut meal gave 8·4 lb. more milk weekly than cows receiving the control diet. Cows given the diet in which the molassed sugar beet pulp in the control diet was replaced by ammoniated sugar beet pulp gave 7·9 lb. more milk weekly than the control group. The milk-fat percentage was not affected by the treatments. Slight increases in solids-not-fat percentage resulted in an increased yield of solids-not-fat with both high-nitrogen treatments. The increases in milk yield approached statistical significance and the increases in solidsnot-fat were significant.3. It was concluded that the feeding trial showed that the nitrogen added to sugar-beet pulp during ammoniation could be utilized by milking cows, but the experiment did not permit an estimate of the efficiency of utilization.4. In the nitrogen balance experiment the utilization of nitrogen was measured as the sum of milk nitrogen and the nitrogen balance. It was concluded that 29·5 g. of nitrogen from 0·8 lb. decorticated ground-nut cake increased the daily utilization of nitrogen by 12·9 g., whereas 55·7 g. nitrogen from 8 lb. ammoniated sugar-beet pulp increased the utilization by only 6·0 g. In this experiment the efficiency of utilization of the nitrogen from groundnut meal was 44% and of the ammonia nitrogen from ammoniated sugar-beet pulp only 11%.5. Ammoniation raised the crude protein content of molassed beet pulp from 10 to 20%. If for the computation of rations the content of digestible crude protein in sugar-beet pulp is taken as 5·0%, that in the ammoniated pulp should be approximately 7·5%.6. If given in sufficient amounts the ammonia nitrogen had as great an effect as the nitrogen of ground-nut meal in correcting the effects of a diet low in protein.

Description: SUMMARYFour experiments investigated some of the factors affecting the digestion of whole maize grain in non-lactating cows and yearling steers. With steers, but not cows, maize in diets containing small amounts of hay (14%) and large amounts of whole grain were better digested than those with 37 or 48% hay. The higher digestibility of maize in steers was associated with a greater time spent ruminating per kg feed and a longer retention time of maize in the gut than in cows. Replacing long roughage with ground and pelleted roughage in diets for steers improved the digestion of whole maize but not as well as reducing the hay to 14% of the diet. Finely grinding the maize produced a large increase in digestibility of the feed in cows and steers and both digested it to the same extent. It was concluded that the motility of the reticulo-rumen during eating and ruminating largely determines the extent of the digestion of whole maize grain.

Description: SUMMARYThree change-over experiments with yearling cattle examined the effects on voluntary intake and digestibility of treating barley, oat and wheat straws with NaOH. Increases in intake due to the NaOH treatment were: with barley straw 31 %, oat straw 9% and with wheat straw 1 %, and the corresponding improvements in digestibility were 36, 13 and 24%. A further three experimentswith yearling heifers and steers measured the effects of supplements on the responsein feeding value to NaOH treatment of wheat straw. Increasing the daily supplement of rolled barley from 10 to 3·4 kg led to a decrease in voluntary intake of treated straw from 4·6 to 3·6 kg organic matter (OM), while including urea, to increase the concentrationof nitrogenin a beet pulp supplement from 19 to 24 gN/kg dry matter (DM), gave an increasein intakeof straw from 3·4 to 4·8 kg OM. Providing more than c. 15 gN/kg dietary DM did not lead to a significant increase in voluntary intake or digestibility. In a further experiment, isonitrogenous supplements of rolled barley and soyabean meal, or rolled barley and fishmeal, led to similar intakes and digestibilities of treatedstraw. The variation in response to NaOH treatment is discussed.