摘要:

AbstractThe kinetics of decline in net photosynthesis and transpiration after cutting was followed in a batch ofLolium multiflorumleaves at light saturation in an assimilation chamber where air temperature, leaf temperature, carbon dioxide concentration and water vapour concentration were controlled. After leaf excision the rates of photosynthesis and transpiration increased or remained the same for 1–2 min and then decreased sharply following a curve with two breaks of slope at 15 min and 30 min. To investigate stomatal behaviour, fragments of leaf tissue were removed, fixed by freezing in liquid nitrogen, then examined by scanning electron microscopy. The stomata were optically closed by 15 min after excision. The practical implications for field drying of Italian ryegrass are discusse

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01405.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractThe acetylene‐reduction method was used to estimate the fixation of atmospheric nitrogen by non‐symbiotic micro‐organisms in soils from England and Wales. Significant fixation was found only in the surface horizon of the soil (0–1 cm) and was much higher in the light than in the dark. The highest rates were found with samples having a well‐developed surface film of blue‐green algae and were from 6 to 10 g ha−1N per h. Generally, rates were very much lower. The addition of fertilizer nitrogen at 100 kg ha−1markedly reduced N fixation by b

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01406.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractHerbage at various stages of growth from three field experiments, one with Italian ryegrass, one with perennial ryegrass and one with white clover, red clover and lucerne, was incubated for 0, 24 or 48 h in rumen liquor followed by 48 h in acid‐pepsin.The proportion of cell content OM in herbage (measured by pepsin) declined with advancing stage of growth more quickly in the legumes than in Italian ryegrass. At a high level of digestibility the legumes had a higher proportion of cell content OM than Italian ryegrass, but the position tended to be reversed at a low level of digestibility.Decline in proportion of cell content and decline in digestibility of cell wall were both major contributors to the decline in digestibility of Italian ryegrass with advancing maturity, whereas in white clover the decline in proportion of cell content was entirely responsible for the decline in digestibility. Lucerne and red clover occupied intermediate positions.At an early vegetative stage rate of digestion appeared to be higher in Italian than in perennial ryegrass. Rate of digestion was higher in the legumes than in the ryegrasses, the difference being largest at an advanced stage of growt

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01407.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractAn experiment repeated in 3 consecutive years in which 0, 200, 400 and 600 kg ha−1fertilizer N was applied annually is described. Cattle on all treatments were offered the same constant daily amount of 2.0 kg herbage DM per 100 kg liveweight above a 3.4 cm height of defoliation. Digestible OM intakes and daily rates of gain were in general not significantly different between treatments. Area required to support these intakes and gains however differed significantly between treatments (P<0.001) and resulted in high outputs of liveweight gain per hectare on all treatments when compared with other published studies. These outputs together with other actual and theoretical outputs were used to predict optimum fertilizer N applications for grazing beef cattle and the predictions discussed in relation to commercial practic

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01408.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractA comparison was made of some factors affecting digestibility in sheep and cattle. In one experiment four castrated male sheep and four non‐lactating cows were given diets of hay and of hay and concentrates, and in another experiment similar groups of animals were offered diets consisting mainly of hay or hay and lucerne cobs. In both experiments there was good agreement in digestibility between the sheep and cows. With diets which did not stimulate maximum rumination, sheep tended to ruminate for a longer time per day than cows. At high feed intakes rumination times were similar in sheep and cows. Times spent eating, ruminating or chewing per unit of feed DM were 6 to 19 times longer in the sheep than in the cows. Retention times of stained hay in the gut tended to be slightly shorter in sheep than cows and those of stained barley husk and of processed lucerne were similar in the sheep and cows. The median size of faecal particles was 1.4 to 1.9 times greater in cattle than sheep. The similarities and differences between sheep and cattle in the factors affecting digestibility are discusse

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01409.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

AbstractGrass 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 fedad libitumand 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 lactat

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01410.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01411.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01412.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Book reviewed in this article:Annual Report for 1975 of the Rowett Research Institute

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1977.tb01413.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY