摘要:

AbstractApplication at spikelet initiation of the growth retardant paclobutrazol (PP333) at a rate of 2.0 kg a.i. ha−1increased the seed yield of perennial ryegrass cv. S24 from 139 to 180 g m−2in 1981, and from 111 to 256 g m−2in 1982. Yield increases were associated with an increased production of fertile tillers in both years and with an increased number of seeds per spikelet in 1982. Other yield components were not changed. Seed yield increased with increasing PP333 application rate in both years. No significant yield difference was recorded between application at spikelet and floret initiation in 1981.Lodging was prevented completely by the 2.0‐kg rate, delayed until after anthesis by the 1.0‐kg rate and began before anthesis with the 0.5‐kg rate. PP333 reduced stem internode length and strengthened the base of the stem; total stem dry matter (DM) was reduced, but root DM accumulation was increased at all rooting depths. Leaf area duration was significantly increased in both years.Vegetative regrowth after seed harvest was not significantly reduced by PP333 application, but soil residual properties were d

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01724.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractA sward of S24 perennial ryegrass was sampled at 4‐weekly intervals over two seasons with either a Haldrup 1500 plot harvester or a hand‐controlled mower fitted with a fixed reciprocating cutter bar. Plot dimensions were adjusted to the width of the machines'cutter bars (1.5 m and 1.0 m respectively) so that there were no discard areas to require removal. Plots were cut either once, or twice in opposite directions. After cutting, residual stubble heights and the proportion of ground surface covered by leaf laminae were recorded.Mean annual dry matter (DM) yields recorded in ten harvests made each year showed no overall significant difference between the machines. However, previous practice had been to sample plots with one pass of the hand‐controlled mower and to trim the sampled area while removing the usual discard strips. The comparison of annual DM yields from one cut taken with the Haldrup or from two cuts taken with the mower, but with the yield at the second cut excluded, showed a mean advantage of 1.55 t DM ha−1a−1for the Haldrup technique or a 14.6% increase over previous practice.Cutting twice significantly (P<0.001) reduced herbage production by a mean of 0.85 t DM ha−1a−1, mean residual stubble height by 9.8 mm and the proportion of ground covered by leaf laminae by 9.8%. Provided that judgment is exercised when planning treatments and layout of trials, it is concluded that the Haldrup 1500 plot harvester is a valuable labour‐saving tool. However, DM yields from trials cut frequently with this machine are likely to exceed those from similar trials cut with a hand‐controlled mower, following the usual G.R.I. Staff

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01725.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe variation between non‐lactating British Friesian cows in eating and ruminating pattern, digestibility and voluntary intake of hay were measured about 4 weeks before calving. Among fourteen of the cows the daily duration of eating ranged from 214 to 462 min and rumination from 410 to 599 min with CV of 20 and 14 respectively. Daily hay intake varied between cows from 5.93 to 11.18 kg dry matter (DM) with a CV of 14. The mean digestibility coefficient of organic matter measured in nineteen cows was 0.57 ± 0.014 s.d. and of cellulose 0.70 ± 0.013 s.d. Intake of hay and cellulose digestibility were correlated (r = 0.51,P<0.05). There was a positive correlation between hay intake and duration of eating (r=0.64,P<0.01) but not between intake of hay and rate of eating. Daily time spent ruminating per kg hay DM eaten was negatively correlated with hay intake (r = 0.66,P<0.01). It is concluded that variation between cows in chewing time and in digestibility of cellulose may be important factors related to variation between cows in voluntary intake of

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01726.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThe relationships between eating behaviour, social dominance and voluntary intake of silage were examined in three experiments. Small groups of Friesian cattle were offered forage as a group in several different situations which caused different degrees of competition for silage. Restriction of the number of mangers available to the cows and of the amount of silage offered encouraged a marked increase in rate of eating silage. In Experiment I when the cows were changed from individual mangers to group feeding their mean eating rate of silage increased from 43 to 71 g silage dry matter min−1. Results from the second experiment provided confirmation. In both experiments submissive cows increased their rate of eating to a greater extent than dominant animals. When group‐fed there was no significant correlation between degree of dominance and variation between cows in voluntary intake of silage, but milk yield and live weight were often directly correlated with silage intake. In Experiment 3 cows and heifers ate similar amounts of silage per unit live weight when group

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01727.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

AbstractThree silages were prepared from perennial ryegrass; unwilted without additive (UW), unwilted treated with 3·5 litres commercial (85%) formic acid (UWA) and prewilted without additive (WN) with dry matter (DM) concentrations of 189, 209 and 328 g kg−1respectively. The three silages were offeredad libitumin a 348‐d feeding experiment to three groups of eight Belgian white‐blue bulls with an initial live weight (LW) of 277 kg. The concentrate (47 g digestible crude protein (CP) kg−1) supplementation was 7·5 g (kg LW)−1. Acid treatment (UWA) slightly improved digestibility of all silage nutrients except CP, whereas wilting generally slightly decreased digestibility of the nutrients except DM and ether extract. The daily LW gain averaged 912 g and was not significantly different on the three different treatments. DM intake per (kg LW)0.75was higher with the UWA silage, 69·3 g, and with the WN silage, 71·6 g, than with the UW silage, 65·8 g. However, this difference in DM intake was not reflected in either daily LW or carcase gain. The DM of UW silage was more efficiently utilized than DM of UW

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01728.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

Book reviewed in this article:Crop Improvement in Eastern and Southern Africa. Research Objectives and On‐Farm TestingEdited by R. A. Kirk

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1985.tb01729.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY