摘要:

AbstractA simple and accurate remote sensing technique for the fine‐scale mapping of grassland protein densities was developed during a study of sward quality and antelope dispersion in Kenya, East Africa. Using measures of spectral reflectance and a vehicular navigation system, estimates of protein densities were recorded at rates exceeding 1000 samples per hour. Nitrogen analyses confirmed that reflectance measures were accurate predictors of protein density for a variety of grass swards but not for two species of sedge. Because the regression coefficients linking reflectance to protein density differed significantly between sward types, good estimates using this method will require a separate calibration for each type of grassland. By monitoring and correcting for variations in ambient light levels, the method can be used under a wide range of lighting conditions and for long periods. This facilitates sampling sufficiently systematically and intensively that contour plots of protein density can be constructed and then correlated with distributions of underlying abiotic factors, foraging activity of sympatric herbivores, or prior maps to characterize successional and historical chang

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01970.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe concentration of mineral elements in herbage from permanent swards of mixed species composition (predominantlyAgrostisspp.,Holcus lanatus, Festuca rubra, Lolium perenne, Poaspp., etc.) was compared with that from sown perennial ryegrass (Lolium perenne) at two fertilizer rates (0 and 300kg N ha−1year−1, both with P and K) and withL. perennel Trifolium repens(at 0 N with P and K). The investigation was conducted over four years at sixteen contrasting sites in England and Wales. Herbage samples for mineral analysis were taken at first and fourth harvests (May and August) each year from plots under 4‐weekly cutting. There was a wide degree of variation between sites, particularly for concentrations of Ca, Mg, Na and all trace elements analysed. Herbage fromL. perennereseeds had significantly higher concentrations of Ca, Mg, Na, Co and S, but K, Mo, Zn, Cu and P were generally lower than in the permanent swards.L. perennel T. repensswards had the highest concentration of major cations, but trace element levels were generally intermediate between those for 0 N permanent andL. perenneswards. Fertilizer N reduced concentrations of Ca, Mn, Mo and S, and increased Mg, Na and Zn, with no consistent effects on K, Co and Cu. Herbage at harvest 4, compared with harvest 1, had higher Ca, Mg, Na, Mn, Zn and S. Permanent andL. perenneswards responded similarly to fertilizer N and between harvest dates. Results are discussed in relation to previous reports of botanical and fertilizer effects on mineral concentrations, and the mineral requirements of livestock. Changes in mineral concentration resulting from reseeding permanent swards are considered unlikely to increase mineral‐related livestock disorders, and in many cases could be beneficial, though problems might arise on sites where some elements, e.g. Cu and Mg,

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01971.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe productivity and persistence of prairie grass (Bromus willdenowiiKunth) cv. Grasslands Matua were compared with a similarly managed endophyte‐free tall fescue × perennial ryegrass hybrid (Festuca arundinaceaSchreb. ×Lolium perenneL.) cv. Johnstone. A field study was conducted on the Appalachian Plateau of southern West Virginia, USA (81°W, longitude; 38°N, latitude; 850m above sea level) for three consecutive years. Nitrogen totalling 0, 168, and 336 kg N ha−1year−1was applied to stands managed as hay. Annual herbage yields were similar for both species in year 1 (1989), but by year 3 (1991) Matua sown‐grass yield was about 35% of first‐year yields. Total herbage yield for Matua plots in the third year was similar to first‐year yields owing to encroachment by non‐seeded grasses and white clover (Trifolium repensL.). Matua was susceptible to powdery mildew [Blumeria graminis(DC) E. O. Speer] in this environment, and was similar in productivity (first year only) and nutritive quality to tall fescue × perennial ryegrass hybrid. Matua use may be limited to areas where low‐temperature stress and resultant winter damage

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01972.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe effects of feeding herbages fertilized with 0 (nil), 32 (low), 66 (medium) or 96 (high) kg of sodium per hectare per year to sheep on herbage digestibility and mineral availability were examined. Modified acid detergent fibre (MADF), ash, magnesium (Mg) and phosphorus (P) contents were increased by the application of sodium (Na) treatments, while potassium (K), sulphur (S) and true protein (TP) contents were reduced. Dry matter (DM) and MADF intakes were increased in the low and medium treatments and DM and MADF digestibility increased in all Na‐treated herbages. The medium‐ and high‐sodium treatments increased salivary Na content and Na/K ratio and decreased K content. Blood K content was not affected by treatment. Intake, faecal output, apparent availability, urinary output and balance of Na were increased by the application of Na treatments. Potassium intake, balance, apparent retention and urinary output were increased by the low, unaffected by the medium and reduced by the high sodium treatment. The low and medium Na treatments increased the intake and apparent availability of Mg; Mg balance and apparent retention were increased by all Na treatments. Feeding the Na‐treated herbages increased intakes, apparent availability, balance and apparent retention of Ca, P and total cations.The low and medium Na treatments increased S intake, faecal output and apparent retention. It is suggested that through increasing the balance and apparent retention of minerals, the application of sodium fertilizer to pasture will improve the mineral status of sheep, particularly at the low and medium application rates employed in this exp

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01973.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIn two changeover design experiments, fifteen early‐ and sixteen late‐lactation cows were used to investigate the effects of offering food beet withad libitumgrass silage and concentrates with different CP content on milk yield and quality. In Experiment 1 (early lactation) cows were offered no fodder beet (0) or 4 kg DM d−1(4) in conjunction with one of three concentrates containing 159, 191 or 244g CP kg−1DM (L.M.H.). Treatments were therefore 1L/0, 1L/4, 1M/0, 1M/4, 1H/0 and 1H/4. In Experiment 2 (late lactation) cows were offered the same level of fodder beet in conjunction with two concentrates containing 129 and 229 (L,H) g CP kg−1DM. Treatments were therefore 2L/0, 2L/4, 2H/0 and 2H/4.In both experiments feeding fodder beet reduced silage DM intakes (P<0·001) and increased total DM intake (P<0·05 toP<0·001). The substitution rate (r) ranged from 0·46 to 0·59kg of silage DM (kg−1fodder beet DM).In Experiment 1, fodder beet tended to increase milk yield, composition and yield of constituents, but the effect was statistically significant for milk protein content only (P<0·01). In Experiment 2, milk yields for 2L/0, 2L/4, 2H/0 and 2H/4 were 11·3, 12·1, 11·7 and 12·5 kg d−1respectively (s.e.d. 0·43, non‐significant), fat contents were 44·4, 47·3, 44·3 and 46·8g fat kg−1respectively (s.e.d. 0·73,P<0·001), protein contents were 34·3, 35·6, 35·3 and 36·2 g protein kg−1respectively (s.e.d. 0·28,P<0·001), fat yields were 494, 574, 512 and 579 g fat d−1respectively (s.e.d. 20,P<0·001) and protein yields were 385, 426, 407 and 442 g protein d−1(s.e.d. 13,P<0·01) respectively.Increasing CP in the concentrate significantly increased milk yield in Experiment 1 (23·9, 22·5, 23·5, 23·8, 26·2, 26·5kg d−1for 1L/0, 1L/4, 1M/0, 1M/4, 1H/0 and 1H/4 respectively,P<0·05). Higher CP in concentrate also resulted in significantly increased milk protein yield in early‐lactation (P<0·001) and milk protein content in late‐lactation (P<0·01) cows. There was a significant interaction between fodder beet and concentr

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01974.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to evaluate the efficiency of two inoculants of lactic acid bacteria (LAB) on grass silages. The evaluation was made in terms of silage composition, rumen fermentation, digestion and animal production. Over a 2‐year period two lots of silage were prepared in two 100‐tonne capacity clamps. In each case an untreated silage and an inoculant‐treated silage were prepared simultaneously from an identical herbage source using independent sets of silage‐making equipment. The inoculant used in the first year was Pioneer Brand 1188 (Pioneer Hi‐Bred UK), and in the second year a slightly different inoculant from the same source (Pioneer Hi‐Bred) was used. The two inoculants were essentially similar in composition, comprising a mixture ofLactobacillus plantarumandStreptococcus faecalis; the strains included in the second inoculant were selected for their capacity to tolerate higher temperatures. The fermentation of the inoculant‐treated silages appeared to be dominated by homofermentative LAB compared with the untreated silages. The use of either inoculant was associated with a change in the rumen volatile fatty acid (VFA) pattern, with a significantly greater molar proportion of propionate and a corresponding reduction in both acetate and butyrate. There was a trend indicating an enhanced efficiency of microbial protein synthesis within the rumen of the heifers for the inoculant‐treated silages, although this was only significant when concentrate was offered with the silage in one experiment. The inoculant‐treated silages had significantly greater intake characteristics than did the untreated silages, though this was not reflected in a statistically significant improvement in average daily liveweight ga

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01975.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFirst‐harvest direct‐cut, double‐chopped grass (190 and 164g DMkg−1in Experiments 1 and 2 resptectively) was ensiled without an additive or, in Experiment 1, with 30 kg t−1grass of an absorbent additive based on sugar beet pulp (Sweet ‘n’ Dry) or with 3·441 t−1grass of formic acid and, in Experiment 2, with 30, 50 and 70 kg t−1grass of Sweet ‘n’ Dry or with 50kg t−1grass of unmolassed sugar beet pulp. The preservation and nutritive value of the silage, in‐silo losses (including silage effluent production), silage intake and animal performance of adult and growing cattle were examined.In Experiment 1 all three silages were well preserved, although the formic acid‐treated silage displayed significantly lower pH, ammonia nitrogen (NH3N) [g kg−1total nitrogen (TN)] and volatile fatty acids (VFAs) than the other two silages. In Experiment 2 absorbent‐treated silages displayed significantly lower pH, buffer capacity (Bc), NH3N (gkg−1TN), CP, modified acid detergent fibre (MADF) and VFAs than untreated silage.Treatment of grass with the absorbent additives at ensiling resulted in reduced effluent production. In Experiment 1 each kilogram of Sweet ‘n’ Dry retained approximately 11 effluent, and in Experiment 2 silages made with Sweet ‘n’ Dry applied at 70kgt−1and sugar beet pulp applied at 50 kg t−1produced similar volumes of effluent and each kilogram of absorbent retained 1·0 and 1·31 of effluent respectively.In Experiment 1 sixty beef cattle [mean initial live weight (LW) 460 kg] were grouped according to LW and allocated to treatment at random. For untreated silage (unsupplemented or with 1 or 2 kg supplement head−1day−1), absorbent‐treated silage (unsupplemented or with 1 or 2 kg supplement head−1day−1) and formic acid‐treated silage (1 kg supplement head−1day−1) the daily silage DM intakes were 6·12, 6·21, 6·40, 7·65, 7·45, 7·11 and 7·85 (s.e. 0·280) kg respectively, the daily liveweight gains were 0·22, 0·56, 0·81, 0·59, 0·74, 0·81 and 0·75 (s.e. 0·071) kg respectively and daily carcass gains were 0·31, 0·47, 0·67, 0·47, 0·61, 0·70 and 0·57 (s.e. 0·043) kg respectively throughout a 75‐day feeding period.In Experiment 2, fifty‐six growing cattle (mean initial weight 312 kg) were grouped according to LW and allocated to treatment at random. For untreated silage (unsupplemented or with 1·5 kg Sweet ‘n’ Dry or 1·5 kg commercial concentrates head−1day−1), silage treated with Sweet ‘n’ Dry at 30, 50 and 70 kg t−1grass and silage treated with 50kg sugar beet pulp t−1grass the daily silage DM intakes were 5·46, 5·28, 5·33, 6·21, 6·27, 6·60 and 6·62 (s.e. 0·154) kg respectively and daily liveweight gains were 0·39, 0·75, 0·81, 0·63, 0·76, 0·94 and 1·75 (s.e. 0·052) kg respectively throughout a 122‐day feeding period. In this experiment 360g kg−1more absorbent was required when it

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01976.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFive experiments were carried out to measure the effects of seed rate and fertilizers on the establishment and early growth of reseeded grass mixtures in the Falkland Islands.Experiments 1 and 2 compared seed rates within the range 7·5‐35kg ha−1. Experiment 3 assessed the effects of three levels of each of nitrogen (N), P2O5, K2O and CaCO3applied as seedbed fertilizers. Experiments 4 and 5 were similar in intent to Experiment 3, but treatments consisted of either nil or a very heavy application of the same fertilizer elements. In all experiments, the grass seed mixtures were sown in late summer after rotavation and burning ofCortaderia pilosadominant indigenous vegetation on peaty soils. Percentage ground cover was estimated in the following spring and dry matter production through the first year was determined by sample harvests.Initially, heavier seed rates resulted in higher percentage ground cover of sown species, but dry matter production over the season following sowing showed a significant increase only between the 25 and 35 kg ha−1rates in Experiment 2. The modest levels of seedbed fertilizers applied in Experiment 3 had no significant effect on either percentage ground cover of sown species or dry matter production. Even at the higher levels used in Experiments 4 and 5, only N consistently increased dry matter yields, although a significant positive response was also obtained from CaCO3in the final harvests.The implications of the results to farmers in the Falkland Islands who may be contemplating reseeding are dis

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01977.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe consequences of controlling sward height at two levels, around 5 cm (HS) and around 3·5 cm (LS), during spring and summer by adjusting weekly the proportion of the areas grazed in response to changes in rate of herbage production and utilizing the surplus pasture areas to conserve winter fodder were studied over three complete years for Greyface ewes with their lambs at 15ha−1(SR15) and 10ha−1(SR10). The rules used to control grazed sward height resulted in acceptable sward height control in three of four treatments and, by providing supplementary feed when sward height was below target, gave rise to similar levels of individual animal performance. Total output of lamb weaned was greater for the SR15 than for the SR10 flocks (607vs477 kg live weight ha−1;P<0·001). Amounts of winter fodder produced were less for the SR15 than for the SR10 flocks [39vs213kg dry matter (DM) per ewe;P<0·001]. Significantly more supplementary feed (10·0vs4·4kg DM per ewe;P<0·01) and hay (13·7vs4·0kg DM per ewe; P7lt;0·05) were offered around mating to SR15 flocks than to SR10 flocks. It is concluded that, provided that sward height can be controlled between 3·5 and 5·0cm during the spring and summer and that supplementation is offered when the grazed sward is below 3·5 cm, flock performance will fall within acceptable and p

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01978.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractWhen grazed sward surface height was controlled within the range 3·75‐5·25 cm during spring and summer, the effects of two annual stocking rates of twenty (SR20) and twelve (SR12) Cheviot ewes per hectare with their lambs and two rates of nitrogen fertilizer, 100(N100) and 200(N200)kg Nha−1per year on animal performance and yield of silage from areas of pasture surplus to grazing requirements were measured. Decision rules for management of sward height resulted in good control of swards and consistent and satisfactory individual animal performance across treatments. Total output of lamb was greater for SR20 than for SR12 (699vs424kg live weight ha−1;P<0·001). Yield of silage was less for SR20 than for SR12 [27vs184 kg dry matter (DM) per ewe;P<0·001] and less for N100 than for N200 (65VS146 kg DM per ewe;P<0·01). Around the mating period, when sward height fell below 3·5cm, supplementary feed was offered. More concentrates were offered to the SR20 than to the SR12 ewes (12·3vs1·2kg DM per ewe;P<0·001) and to the N100 than to the N200 ewes (8·3vs5·2kg DM per ewe;P<0·01); trends in the amounts of hay offered during that pe

ISSN:0142-5242    

DOI:10.1111/j.1365-2494.1994.tb01979.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY