THE USE OF LIVEWEIGHT-GAIN TRIALS FOR PASTURE EVALUATION IN THE TROPICS

An experiment is described in which liveweight gains were measured from two grass/legume pastures using small East African Zebu animals and also progeny of small East African Zebu cows crossed with Bos taurus bulls. Significantly higher production was obtained from cross-bred stock, which averaged 706 lb liveweight gain at per annum (791 kg/ha per annum), compared with 509 lb liveweight gain/ac per annum (571 kg/ha per annum) from Zebu stock, indicating that pasture management had advanced beyond the genetic potential of the local Zebu stock. The problems of designing, conducting and interpreting the results of such grazing trials are discussed.     

THE UTILIZATION OF GRASS FED INDOORS TO YOUNG BEEF CATTLE, WITH OR WITHOUT SUPPLEMENTARY BARLEY

An experiment was carried out in which grass was cut and fed indoors, with or without supplementary barley. Seven animals were allocated to each of the following treatments: (1) grass ad lib . without supplementary barley; (2) grass ad lib . with supplementary barley at the rate of 0.5 lb/100 lb bodyweight; (3) grass ad lib . with supplementary barley at the rate of 1 lb/100 lb bodyweight. Supplementary barley increased total dry-matter intake and improved daily liveweight gain and food conversion rate. The mean daily liveweight gains for the 17-week experimental period were 1.60, 1.91 and 2.20 lb and the corresponding feed dry-matter conversion ratios were 6.18, 5.67 and 5.55 for Treatments 1, 2 and 3, respectively.
The dry-matter digestibility of the diets was slightly higher when the grass was supplemented with barley than when grass alone was given. Although barley depressed the digestibility of protein, the absolute and the proportionate retention of nitrogen was increased. This was particularly marked on Treatment 3, presumably because of the higher net energy value of the diet containing the greater amount of barley. The N-retention data corresponded to the rates of liveweight gain obtained.     

DRYING AND CONDITIONING OF DIRECT–HARVESTED TIMOTHY SEED

An experiment is described in which S48 timothy seed, direct harvested at 3 stages of ripeness, was dried in layers 6 in. deep, at air temperatures from 75–135° F, immediately after harvest and after periods of from 1 to 3 days conditioning with cold air. Germination results for non-conditioned seed showed good agreement with those obtained in the previous year. The quality of seed hulled during threshing was inferior to that remaining unhulled after threshing, but the latter was more susceptible to high air temperature during drying. The relationship of the seed obtained in this experiment to commercial seed is discussed and a scheme for the practical application of the results will be presented in a subsequent paper.     

THE EFFECT OF THE BIPYRIDYL HERBICIDES ON HILL COMMUNITIES AND THEIR ROLE IN THE IMPROVEMENT OF HILL GRAZING

The improvement of hill land is important to the national economy of the United Kingdom. An increase in the amount of enclosed productive land results in a greater stock-carrying capacity of a hill farm. Improvement is not always possible by conventional implements, and herbicides are being used to kill the old sward. The bipyridyl herbicides offer a means of destroying or modifying the indigenous vegetation. The application of low doses of paraquat or diquat to an association containing Molinia caerulea, Nardus sfricta and Festuca avina resulted in a change in equilibrium in favour of the fescues. The application of 2 lb paraquat per acre practically eliminates all grass species in a sward and it is then possible to establish desirable pasture species after lightly cultivating the dead surface litter.     

THE EFFECT OF HISTAMINE ON SILAGE DRY-MATTER INTAKE

The oral introduction of 0·5 g histamine as the diphosphate into the rumen of sheep produced no effect on the physiological condition of the animals. The feeding of histamine, as the dihydrochloride, in levels up to 1 g/day to sheep on silage diets did not affect the dry-matter intake.     

THE EFFECT OF DEFOLIATION ON THE SEED-PRODUCING CAPACITY OF BRED VARIETIES OF GRASSES

Leafy grass varieties S24 perennial ryegrass, S26 cocksfoot, S215 meadow fescue and S51 timothy were cut in October and at various growth stages in spring; S53 meadow fescue was grazed at similar periods. Sub-plots were given different applications of N. The control plots had similar manurial treatments but were not defoliated. The seed yield of S24 following October cutting was significantly lower than the control in the first harvest year and significantly higher in the second; the mean yields over 2 years, as a result of cutting at this stage and before ear formation in March, were very similar to those of the control treatment. The mean yields from 3 harvest years for S26, S215 and S51 were generally improved by cutting in October and before ear formation, but cutting after ear formation reduced the number of heads and the seed yields. Extra N applied in conjunction with the defoliation had no significant effect on the number of seed heads or on seed yield. Double grazing of S53 in Sept. and Dec. reduced significantly its seed production in both harvest years. Application of N in spring gave a greater response than a similar application in autumn.     

Untersuchungen zum Reihenabstand im Kartoffelbau. III. Sammelernte

Ohne Zusammenfassung     

Nekrosen an kartoffelkeimen,ein Symptom von Mosaikviren

Zusammenfassung In Erg?nzung der Angaben vonMartin undQuemener übe eine Fleckung belichteter Dunkelkeime infolge Infektion durch Mosaikviren wurde festgestellt, da? auchNekrosen auftreten k?nnen. Diese sind das Anzeichen einer schweren Erkrankung. Bei den untersuchten Sorten waren sie in der überwiegenden Mehrzahl der F?lle durch Mischinfektion mit Y- und X-Virus verursacht, doch werden nicht alle diese Infektionen durch die Entwicklung von Nekrosen kenntlich. Keime mit Nekrosen bleiben meist in der Entwicklung zurück; bei Farbfleckung ist diese Wachstumsdepression im allgemeinen schw?cher ausgepr?gt.

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Summary Martin andQuemener found that tubers infected with mosaic viruses could be recognized by the irregular spotty coloration which, after exposure to light, developed on sprouts grown in the dark. If the symptoms are very marked (heavy crinkle or streak), especially in the case of mixed Y and X virus infections, necroses appear on the sprouts in addition to or instead of the coloured spots, especially at their bases. These necroses are very different from the nonviral “necrobioses” of the sprout apex or cell elongation zone 1–2 mm below the tip. The necrotic virus spots are of a lighter, brownish colour than the blackish-brown necrobioses, which frequently form stripes running from tip to base. Necrotic sprouts usually exhibit a pronounced decline in growth. Development of sprouts showing only irregular spotty coloration is less inhibited. When examining potato tubers for mosaic virus infection necroses can be regarded as a additional symptom to the irregular spotty coloration. Sprouts 3–5 cm in length grown in the dark were exposed to daylight for some days. The testing of sprouts developed after desprouting gives better results than the testing of the original sprouts. Moreover, the number of tubers with necrotic sprouts increases with increasing sprout age.

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Résumé Martin etQuemener signalent que les tubercules infectès par les virus des mosa?ques peuvent étre reconnus à la coloration en taches irrégulière qui apparait sur les germes cultivés dans l'obscurité lorsqu'on les expose à la lumière. Si les sympt?mes sont tres prononcés (forte frisolée ou bigarrure), surtout dans le cas des infections mixtes à virus Y et X, les colorations en taches des germes sont accompagnées ou remplacées par des nécroses, surtout à la base des germes. Ces nécroses sont toutes différentes des “nécrobioses” non provoquées par des virus, que l'on trouve à la pointe des germes ou dans la zone d'allongement cellulaire à 1 ou 2 mm au dessous de la pointe. Les nécroses à virus ont une couleur brune plus claire que les nécrobioses brun-noir, qui forment souvent des lignes allant de la pointe à la base ddu germe. En général, la croissance des germes nécrotiques est nettement réduite. Le développement des germes présentant uniquement une coloration en taches irrégulière est moins fortement retardé. A l'examen des tubercules de pomme de terre relatif aux virus des mosa?ques, les nécroses peuvent être considérées comme un sympt?me supplémentaire à c?té de la coloration en taches irrégulière. Les germes de 3 à 5 cm de longueur poussés dans l'obscurité sont exposés à la lumière du jour pendant quelques jours. L'examen des germes qui ont poussé après l'enlèvement des germes déjà présents fournit de meilleurs résultats que celui des premiers germes apparus. De plus, le nombre de tubercules à germes nécrotiques augmente avec l'age des germes.