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1.
The DM digestibility (DMD) and organic matter digestibility (OMD) of 36 tropical grass samples were determined both in vivo and in vitro. Regressions relating OMD to DMD were calculated. In vivo OMD=1·02 in vivo DMD+ 0·1, r=0·99. In vitro OMD=1·05 in vitro DMD—4·7, r=0.99. At the same DMD, the in vitro method predicted OMD 2·8 to 3·4 percentage units lower than the in vivo method. This difference was caused by the difference in mean apparent digestibility of the ash, in vitro 71%, in vivo 47%. In vivo DMD was correlated (r=0·92, P<0·01) with in vitro DMD and the regression relating these two factors had a residual standard deviation of ±1·42 digestibility units. This deviation was reduced to ±1·9 digestibility units when OMD was determined. For both DMD and OMD significant differences were found between grass species in the relation between in vivo and in vitro digestibility. To overcome biased estimates of OMD it was suggested that conversion equations should be avoided, and that the in vitro method be standardized with samples of known in vivo OMD as similar as possible to those being tested.  相似文献   

2.
The effect of the structure of a tropical pasture, based on Dichanthium spp., on the ingestive behaviour, in vivo digestibility of the diet and herbage intake by eight Creole tethered heifers was studied. Two levels of nitrogen fertilizer (0 and 50 kg ha?1) were applied to plots after each grazing cycle and there were 28 d between each of the three grazing cycles. Four heifers grazed individual subplots daily on each plot for 14 d in each of the successive grazing cycles. Simultaneous measurements of bite depth, bite mass, biting rate, short‐term intake rate and daily grazing time were made in two 4‐d periods at the end of each 14‐d period. The in vivo organic matter digestibility (OMD) and daily herbage organic matter intake (OMI, expressed on a kg LW0·75 basis) were also measured at the same times. Relationships among pasture characteristics and ingestive behaviour were similar to those reported in other short‐term studies: pasture height was highly correlated with bite depth, bite mass and biting rate (r = 0·91, r =0·79 and r = ?0·68, respectively, P < 0·001). Pasture variables had lower correlations with grazing time and short‐term intake rate than with bite depth, bite mass and biting rate. Pasture structure was more highly correlated with OMD than OMI: leaf mass and length and also the extended tiller length were highly correlated with OMD (r = 0·77, r = 0·76 and r = 0·72, respectively, P < 0·001) whereas the crude protein concentration of the herbage was correlated with OMI and digestible OMI (r = 0·50 and r = 0·69, respectively, P < 0·001). Ingestive behaviour variables, as well as OMD, were correlated more with pasture characteristics than was OMI.  相似文献   

3.
The effects of rate of inorganic nitrogen (N) fertilization (0, 80 or 160 kg N ha?1 per regrowth), season of harvest (regrowths 1, 2 and 3) and perennial ryegrass (Lolium perenne L.) cultivar [classified as having either a normal or elevated water soluble carbohydrate (WSC) concentration genotype] on in vitro gas production and digestibility were assessed. Increased N fertilizer application significantly decreased total gas production (TGP), methane (CH4) production and organic matter digestibility (OMD). The results suggest that the decreases in TGP and CH4 production were associated with a restriction in organic matter (OM) fermentation and an altered crude protein (CP) to structural carbohydrate ratio rather than a modification in the stoichiometry of fermentation. Season of harvest only significantly (P < 0·05) altered in vitro OMD and CH4 production at 8 h, despite altering the chemical composition of the herbage. Cultivar effects on all measured in vitro parameters were not significant presumably because the elevated WSC concentration trait was not expressed strongly in the study.  相似文献   

4.
Advancing maize crop maturity is associated with changes in ear‐to‐stover ratio which may have consequences for the digestibility of the ensiled crop. The apparent digestibility and nitrogen retention of three diets (Early, Mid and Late) containing maize silages made from maize of advancing harvest date [dry matter (DM) contents of the maize silages were 273, 314 and 367 g kg?1 for the silages in the Early, Mid and Late diets respectively], together with a protein supplement offered in sufficient quantities to make the diets isonitrogenous, were measured in six Holstein–Friesian steers in an incomplete Latin square design with four periods. Dry‐matter intake of maize silage tended to be least for the Early diet and greatest for the Medium diet (P = 0·182). Apparent digestibility of DM and organic matter did not differ between diets. Apparent digestibility of energy was lowest in the Late diet (P = 0·057) and the metabolizable energy concentrations of the three silages were calculated as 11·0, 11·1 and 10·6 MJ kg?1 DM for the Early, Medium and Late diets respectively (P = 0·068). No differences were detected between diets in starch digestibility but the number of undamaged grains present in the faeces of animals fed the Late diet was significantly higher than with the Early and Mid diets (P = 0·006). The apparent digestibility of neutral‐detergent fibre of the diets reduced significantly as silage DM content increased (P = 0·012) with a similar trend for the apparent digestibility of acid‐detergent fibre (P = 0·078). Apparent digestibility of nitrogen (N) was similar for the Early and Mid diets, both being greater than the Late diet (P = 0·035). Nitrogen retention did not differ between diets. It was concluded that delaying harvest until the DM content is above 300 g kg?1 can negatively affect the nutritive value of maize silage in the UK.  相似文献   

5.
Remote sensing of nitrogen (N) concentration and in vitro dry matter digestibility (IVDMD) in herbage can help livestock managers make timely decisions for adjusting stocking rate and managing pastures during the grazing season. Traditional laboratory analyses of N and IVDMD are time-consuming and costly. Non-destructive measurements of canopy hyperspectral reflectance of pasture may provide a rapid and inexpensive means of estimating these measures of nutritive value. Using a portable spectroradiometer, canopy reflectance was measured in eight warm-season grass pastures in the USA in June and July in 2002 and 2003 to develop and validate algorithms for estimating N concentration and IVDMD of herbage. Nitrogen concentration of herbage was linearly correlated (r = 0·82; P < 0·001) with a ratio of reflectance in the 705- and 1685-nm wavebands (R705/R1685) and IVDMD was correlated with R705/R535 (r = 0·74; P < 0·001). Compared with simple linear regressions of N concentration and IVDMD in herbage with two-waveband reflectance ratios, multiple regression, using maximum r2 improvement, band-depth analysis with step-wise regression, and partial least-squares regression enhanced the correlation between N concentration and IVDMD of herbage and canopy reflectance values (0·81 ≤ |r| ≤ 0·90; P < 0·001). Validation of the prediction equations indicated that multiple regression only slightly improved accuracy of a model for predicting N concentration and IVDMD of herbage compared with simple linear regression of reflectance ratios. Results suggest that the N concentration and IVDMD of herbage of warm-season grass pastures can be rapidly and non-destructively estimated during the grazing season using canopy reflectance in a few narrow wavebands.  相似文献   

6.
This study aimed to determine the fermentation characteristics, nutrient composition and in vitro digestibility of desert wormwood (DW, Artemisia desertorum Spreng.) silage as the sole ingredient, or mixed with high‐moisture maize (corn) straw (HMCS). Desert wormwood and HMCS were harvested and chopped (1–2 cm) then ensiled in laboratory silos (25 cm high with an internal diameter of 7·6 cm) at a density of 550 g L?1 at room temperature for 60 days. The proportions of DW in the DW/HMCS mixtures were 1, 0·75, 0·50, 0·25 and 0, based on fresh weight. The silages were analysed for fermentation characteristics, nutrient composition and in vitro digestibility. Desert wormwood ensiled with HMCS had lower pH and acetic acid concentration and higher lactic acid concentration as the proportion of DW decreased. As the proportion of DW decreased, the crude protein concentration and the in vitro digestibility of dry matter increased and the concentrations of neutral detergent fibre, acid detergent fibre and acid detergent lignin decreased. This study has indicated that mixing HMCS with DW can improve the fermentation quality and nutrient composition of these silage mixtures.  相似文献   

7.
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8.
The aim of this experiment was to study the effect of feeding level (FL) on the digestibility of unconserved forage obtained from two permanent grasslands cut at three different dates during the first cycle of growth. Forage was offered to Texel sheep (wethers), at maintenance level and at ad libitum level. Differences in voluntary intake (VI) between grasslands were also tested. Organic matter digestibility (OMD) measured at ad libitum level and at VI was 13% higher on harvested forage from grassland rich in forbs (GRF) than grassland rich in grasses (GRG) at early herbage growth stages, but these differences were no longer found at later maturity stages. In GRF, there were no differences for OMD, at either FL at the young growth stages, but at the end of the cycle the OMD obtained at ad libitum level (0·56) was higher than that at maintenance level (0·50). However, in GRG, at an early stage of forage maturity, OMD at ad libitum level (0·67) was lower than that at maintenance level (0·70), but this difference was no longer found at the end of the growth cycle. In conclusion, the effect of FL on the digestibility of unconserved forage from permanent grasslands depends on the type of grassland. These differences are mainly explained by the different botanical composition of the grassland types.  相似文献   

9.
First and second harvests of lucerne (Medicago sativa L.), perennial ryegrass (Lolium perenne L.) and a lucerne–perennial ryegrass mixture [80 or 144 g kg?1 dry matter (DM) of ryegrass] at the first and second harvests were cut and conditioned, wilted to 500 or 700 g DM kg?1 then baled and stretch‐wrapped for silage on the same dates. Lucerne bales were denser (411 kg m?3) than bales of perennial ryegrass (331 kg m?3) (P < 0·05). After an 8‐month storage period, silage made from high DM‐content forage had a higher concentration of neutral‐detergent fibre (NDF) and was less digestible than that made from low DM‐content forage. Daily DM intakes by beef steers, when the silages of the second harvest were fed ad libitum, were 31·2, 31·2 and 22·3 g kg?1 live weight for lucerne, lucerne–perennial ryegrass mixture and perennial ryegrass silages, respectively (P < 0·01), when the herbage had been wilted to 500 g kg?1. In vivo digestibility of NDF in the lucerne–perennial ryegrass mixture silage (0·587) was significantly lower than that of perennial ryegrass silage (0·763) but higher than lucerne silage (0·518). Higher intakes of baled lucerne silage tended to offset its lower digestibility values. Lucerne–perennial ryegrass mixture silage had a higher DM and NDF digestibility than lucerne silage, indicating perhaps the presence of associative effects.  相似文献   

10.
The aim of this study was to evaluate the possible effect of pre‐fermented juice (PFJ) on the fermentation quality and nutritive value of first‐cut lucerne (Medicago sativa L.) silage. The PFJs were prepared using barley (B), wheat (W) and grass herbages (G). Both fresh (PFJ‐B, PFJ‐W and PFJ‐G) and frozen (PFJ‐BF, PFJ‐WF and PFJ‐GF) PFJs were examined. Frozen PFJs were prepared by freezing fresh PFJs at ?22°C with 20% glycerol (v/v). Treatments of lucerne silage included (1) control; (2) silage treated with PFJ‐B; (3) silage treated with PFJ‐W; (4) silage treated with PFJ‐G; (5) silage treated with PFJ‐BF; (6) silage treated with PFJ‐WF; and (7) silage treated with PFJ‐GF. All the treatments consisted of five replicate silos, and they were prepared in 1·0‐L glass jar silos. Results showed that silages treated with fresh and frozen PFJs, regardless of plant material, had better fermentation quality than the control silage in terms of lower pH, butyric acid (BA) and ammonia nitrogen (NH3‐N) concentrations, as well as higher lactic acid (LA) concentration (P < 0·05) and in vitro organic matter digestibility (IVOMD), metabolizable energy (ME) content, and gas production values (P < 0·05). Results indicated that PFJ treatments enhanced the nutritive value, fermentation quality and IVOMD, ME content and gas production values of first‐cut lucerne silages.  相似文献   

11.
This study was conducted to determine the chemical composition and nutritive value of Prangos ferulacea, a plant found in the Mediterranean and Middle‐east regions, where it is used as animal fodder. Samples of mature plants were collected from S.E. Turkey. Metabolizable energy (ME) values were estimated from in vitro gas production measurements and from chemical composition. ME concentrations of the whole plant, leaves and stems were estimated to be 12·2, 11·9 and 12·7 MJ kg?1 dry matter (DM) respectively, which compares favourably with high‐quality forages commonly used in ruminant feeding. The DM degradability of the whole plant, leaves and stems increased up until 48 h of in situ incubation, 866, 915 and 784 g kg?1 DM respectively, but changed little between 48 and 72 h. In vitro DM and organic matter digestibility of the whole plant, leaves and stems were 0·769 and 0·806, 0·773 and 0·790, and 0·740 and 0·840 respectively. The results show that P. ferulacea may be regarded as a high‐energy forage, but further research is needed on its intake characteristics and the levels of animal performance that can be achieved from its inclusion in the diet.  相似文献   

12.
The chemical composition of silage consumed by cattle can influence the subsequent rumen microbial fermentation patterns and methane (CH4) emissions. The objectives of this study were to (i) evaluate the effect of ensilage on the in vitro rumen methane output of perennial ryegrass and (ii) relate the silage fermentation characteristics of grass silages with in vitro rumen methanogenesis. Three pre‐harvest herbage‐conditioning treatments and seven silage‐additive treatments were used in a laboratory‐scale silo experiment to produce a diversity of silage fermentation characteristics. Ensilage reduced (P < 0·01) the in vitro rumen CH4 output (mL CH4 g?1 dry matter (DM) disappeared). This reflected differences in the direction of rumen fermentation (lower acetic (P < 0·05) and higher propionic (P < 0·001) acid proportions in volatile fatty acids) rather than major changes in the extent of in vitro rumen fermentation (i.e. mmol VFA g?1 DM). The magnitude of the decrease in CH4 output (mL g?1 DM incubated) owing to ensilage increased as the extent of silage fermentation, and in particular the lactic acid concentration, increased. In contrast, among silages with relatively similar extents of silage fermentation (i.e. total fermentation products), an increase in the proportion of lactic acid in silage fermentation products led to a more extensive in vitro rumen fermentation and thus to a greater CH4 output (mL g?1 DM).  相似文献   

13.
Forty‐eight high‐yielding dairy cows of the Swedish Red breed were used to examine the effects of providing pea–oat silage (P), grass–clover silage (G) and a 0·50:0·50 mixture of the silages (M) ad libitum in diets with two concentrate levels (7 or 10 kg d?1). A 9‐week experiment, including a 2‐week pre‐experimental period in which the cows were all fed the same diet, and an in vivo apparent digestibility study were conducted comparing the six dietary treatments (M7, M10, P7, P10, G7, G10). Intake and digestibility of the diets and milk production and live weight of the cows were measured. The G silage [11·3 MJ ME kg?1 dry matter (DM)] was first‐cut grass herbage wilted for 24 h prior to addition of an additive, containing formic acid, propionic acid and ammonia, at 4 L t?1 fresh matter (FM). The P forage was cut when the peas were at pod fill and ensiled directly with 6 L t?1 FM of the same additive. The main hypothesis tested, that cows fed the M silage would produce more milk than the cows fed either the P or the G silages, was confirmed. The cows fed the M7 dietary treatment had similar milk yield and milk composition to cows offered the M10, G10 and P10 dietary treatments, and cows offered the G7 and P7 dietary treatments had lower milk and milk protein yields. This suggested that a mixed ration of pea–oat bi‐crop and grass–clover silage has a concentrate‐sparing effect, and that the use of pea–oat bi‐crop and grass–clover silage as a mixed ration for high‐yielding dairy cows can be recommended.  相似文献   

14.
Abstract Two experiments were carried out in consecutive years to examine the influence of cutting date and restricting fermentation by carboxylic acid treatment on the nutrient intake from grass silage by beef cattle. In year 1, four cutting dates during July and August after a primary growth harvest and, in year 2, five cutting dates of primary growth between mid‐May and early July were examined. Herbage was ensiled either untreated or treated with high levels of acid additive (‘Maxgrass’, mean 8·6 l t?1). Ninety‐six (year 1) or forty‐eight (year 2) continental cross steers were used in partially balanced changeover design experiments with each silage type either unsupplemented or supplemented with 4·5 (year 1) or 5·5 (year 2) kg concentrates head?1 d?1. Silage digestibility declined significantly between initial and final harvest dates (P < 0·001), whereas silage dry‐matter (DM) and digestible energy (DE) intakes were significantly higher in the initial compared with final harvest dates in both years of the study (P < 0·01). Similarly, silage DM and DE intakes, and total DM intakes, of acid‐treated and unsupplemented silages were greater than those of untreated and concentrate supplemented silages, respectively (P < 0·001). The results indicate that earlier cutting dates, and addition of acid to herbage before ensiling, can increase silage DM intake by beef cattle.  相似文献   

15.
An experiment was conducted to compare the nutritive value of a range of ensiled forage legumes. Silages were prepared from late second‐cut lotus (Lotus corniculatus), first‐cut sainfoin (Onobrychis viciifolia) and both early and late second‐cut red clover (Trifolium pratense) and lucerne (Medicago sativa). Each experimental silage was offered to six Suffolk‐cross wether lambs, aged 10 months, housed in metabolism crates. Voluntary intakes of dry matter ranged from 71 to 81 g kg?1 liveweight0·75 d?1. Voluntary intakes were similar on the lotus, sainfoin and late‐cut red clover silages, but the voluntary intake on the lotus silage was significantly higher than that on the lucerne silages and early‐cut red clover silage. Digestibility of organic matter in the dry matter was highest for the lotus silage (0·650), and lowest for the sainfoin silage (0·527). Although most of the N in the sainfoin silage appeared to be in an indigestible form, N digestibility was approximately 0·70 for the other legume silages. The highest loss of N in urine, 0·75 of N intake, was recorded for lambs offered the lucerne silage. Differences in N intake, N loss in faeces and N loss in urine led to statistically significant differences in the amount of N retained, with the highest and lowest N balances recorded for the lotus (16 g N d?1) and sainfoin (?2 g N d?1) silages respectively. The results confirm that these high protein forages have high intake potential. While low N digestibility appears to limit the nutritional value of sainfoin, further research could formulate feeding strategies that improve the efficiency with which the protein from red clover, lucerne and lotus is utilized.  相似文献   

16.
Dorycnium hirsutum and D. rectum are perennial legumes which may have potential for use as pastures for the control of groundwater recharge in southern Australia. Little is known about the quality of the forage of Dorycnium species for grazing livestock or how these species respond to cutting. The effect of cutting height on plant survival, production of dry matter (DM), the proportion of leaf, edible stem (approximately <5 mm diameter) and woody stem in the DM and the nutritive value of the edible components was investigated. Biomass above five cutting‐height treatments (uncut, ground level, 5–8 cm, 10–15 cm and 15–30 cm above ground level) was removed at 8‐week intervals from plots of D. hirsutum and D. rectum from September 2002 to July 2003. In both species, plants subjected to lower cutting height treatments produced less DM above the height of the cut than those cut at higher heights. DM production declined over time in all treatments. Plants cut to ground level failed to regrow after the second harvest in D. hirsutum and the fourth harvest in D. rectum. Thus, these Dorycnium species were susceptible to high severity defoliations at 8‐week intervals. Negligible inedible woody stem was present in regrowth of both species after 8 weeks but D. hirsutum regrowth had a higher proportion of leaf (0·72) than D. rectum (0·56). Plants left uncut accumulated a large proportion of inedible woody stem in the DM (0·69 in both species) by July 2003, particularly at the base of the plant. Edible DM from regrowth of D. hirsutum and D. rectum had crude protein (CP) concentrations of 120 and 150 g kg?1 DM; dry matter digestibility (DMD) values of 0·45 and 0·58; organic matter digestibility (OMD) values of 0·50 and 0·64; neutral‐detergent fibre (NDF) concentrations of 370 and 290 g kg?1 DM; and acid‐detergent fibre (ADF) concentrations of 260 and 210 g kg?1 DM, respectively. Medicago sativa, grown under similar conditions, had higher digestibility values (0·63 DMD and 0·66 OMD) and similar CP concentrations to D. rectum (140 g kg?1 DM), but higher concentrations of NDF and ADF (410 and 290 g kg?1 DM). Leaf material from both Dorycnium species had a higher nutritive value than edible stems, with DMD and OMD values of leaf of D. rectum being 0·68 and 0·74 respectively. Uncut plants had a much lower nutritive value of edible DM than the regrowth from cut treatments; older material was also of a lower nutritive value. The relatively low nutritive value of even the young regrowth of Dorycnium species suggests that forage quality is a major limitation to its use. Forage of Dorycnium species could be used during periods when other sources of forage are in short supply but infrequent grazing it is likely to produce forage of a low nutritive value.  相似文献   

17.
This experiment evaluated a bacterial inoculant based on a single strain of Lactobacillus plantarum as a silage additive. Three silages were harvested on 8 September 1989 from the second regrowth of a perennial ryegrass sward, which had received 167 kg N, 28 kg P2O5 and 45 kg K2O ha?1. Mean dry matter (DM) and water soluble carbohydrate concentrations of the herbages at ensiling were 148 g kg?1 and 78 g.(kg DM)?1 respectively. Herbages were treated with either no additive (C), formic acid (3·0 1 t?1) (F) or the inoculant (3·0 1 t?1) (I) and were ensiled in three 80-t capacity silos. For silages C, F and I respectively, pH values were 4·70, 3·77 and 4·47, ammonia-N concentrations were 192, 111 and 182 g (kg total N)?1 and butyrate concentrations were 6·8, 1·8 and 7·1 g (kg DM)?1. The silages were offered ad libitum and supplemented with 2·0 kg concentrates per head daily to thirty-six heifers (mean initial live weight 442 kg). For silages C, F and I, silage DM intakes were 12·7, 14·4 and 14·1 (s.e. 0·42) g (kg live weight)?1, metabolizable energy intakes were 155, 166 and 172 (s.e. 5·1) kJ (kg live weight)?1, and estimated carcass gains were 456, 519 and 518 (s.e. 28·1) g d?1 respectively. A further 18 similar cattle were used in studies on the digestibility of the silages, and rumen degradation of each was estimated with three mature cattle. Inoculant treatment significantly increased crude fibre (P <0·01), neutral detergent fibre (P <0·01), modified acid detergent fibre (P <0·01), hemicellulose (P <0·05) and N digestibilities (P <0·05) and tended to increase N retention from the total diet. It is concluded that although treatment of herbage that was difficult to ensile with the inoculant did not improve silage fermentation, it significantly increased digestibility, especially of the fibre fractions, and silage DM intake and tended to increase animal performance to levels similar to those achieved with a well preserved formic acid-treated silage. Increases in silage DM and metabolizable energy intakes are likely to have been attributable to the effects of the inoculant on digestibility, especially of the fibre fractions.  相似文献   

18.
Excellent winter hardiness, persistence and nutritive value of both kura clover (Trifolium ambiguum M. Bieb.) and reed canarygrass (Phalaris arundinacea L.) suggest that intercropping these species could substitute for lucerne (Medicago sativa L.). The dry matter (DM) yield and nutritive value of herbage, and silage characteristics of kura clover‐reed canarygrass (KC‐RCG) herbage, were compared to those of lucerne over two growth cycles near Arlington, WI, USA. First and second growths of lucerne and KC‐RCG herbage were sampled four times at 1‐week intervals and ensiled for 100 d. Yield of DM of the KC‐RCG was 0·23–0·57 greater than that of lucerne on sampling dates in the first growth cycle, with no differences in DM yield in the second growth cycle. The pH of lucerne silage was lower than that of KC‐RCG silage in the first growth, and the opposite occurred in second growth, which was attributed to maturity differences and the proportion of kura clover in the mixture. Lactate concentration was lower in KC‐RCG than lucerne silages in both growth cycles. The lucerne and KC‐RCG silages had similar in vitro DM digestibility except for the final sampling date in the first growth cycle when neutral‐detergent fibre concentration of KC‐RCG herbage exceeded 550 g kg?1 DM. Crude protein concentration was greater in lucerne silage than in KC‐RCG silage in both growth cycles. Overall, differences in nutritive value and silage fermentation between the two herbages were minimal across growth cycles. These results suggest that a KC‐RCG sward is a viable alternative to lucerne in northern environments of the USA where lucerne production may be limited by winter injury or edaphic factors.  相似文献   

19.
In change‐over trials, mid‐lactation dairy cows were fed concentrate‐supplemented, isonitrogenous and isofibrous perennial ryegrass–legume silage diets that satisfied energy requirements but were suboptimal with respect to metabolizable protein supply. Legumes were either birdsfoot trefoil with low levels of condensed tannins (typical for hemiboreal conditions), or white clover. Averaged over two experimental years, birdsfoot trefoil–based silage resulted in lower digestibility (P < 0·001) of dry matter (50 g kg?1), organic matter (52 g kg?1), neutral detergent fibre (120 g kg?1) and nitrogen (24 g kg?1) and lower rumen total volatile fatty acid concentration (7 mm ; P = 0·009). Milk protein yield was 36 g d?1 higher with birdsfoot trefoil silage (P = 0·002), while raw milk yield tended to be 0·8 kg d?1 higher (P = 0·06). Rumen ammonia concentration was similar between diets, but milk urea concentration (P < 0·001), urinary urea excretion (P = 0·002) and faecal‐N proportion (P = 0·001) were higher with birdsfoot trefoil silage. The results suggest that grass–birdsfoot trefoil silage produced in hemiboreal areas exhibits a protein‐sparing effect in dairy rations, despite a low condensed tannin content that is further diluted by companion grasses and ration concentrate proportion.  相似文献   

20.
Abstract An experiment was carried out over 2 years to evaluate the effects of increasing the proportion of cereal‐based concentrates in diets containing high‐digestibility and conventional medium‐digestibility grass silages on the dry‐matter (DM) intake, liveweight gain and carcass composition of beef cattle, and to examine the effects of grazed grass and the ratio of grass silage:concentrates in the diet on the fatty acid composition of selected muscle tissues. Late‐maturing steers (n = 231) were offered diets based on high‐digestibility (HD) (0·743 digestible organic matter (DOM) in DM) or medium‐digestibility (MD) (0·643 DOM in DM) grass silages supplemented with barley/soyabean meal‐based concentrates. The concentrates constituted 0·20, 0·40, 0·60 and 0·80 of total DM of the diets, which were offered ad libitum (AL). The two diets, which contained 0·80 concentrates, were also offered at 0·80 of AL intake. A further group of fourteen animals were given the medium‐digestibility silage only for 5 months and then grazed perennial ryegrass pastures for a further 5 months (silage/pasture treatment). For the diets containing HD silage and 0·20, 0·40, 0·60 and 0·80 concentrate, and 0·80 concentrate at 0·8 of AL intake, the DM intakes were 9·4, 10·2, 10·4, 10·2 and 8·1 (s.e. 0·16) kg d?1, respectively, and daily carcass gains were 0·67, 0·78, 0·77, 0·79 and 0·62 (s.e. 0·029) kg d?1, respectively; for those containing MD silage and 0·20, 0·40, 0·60 and 0·80 concentrate, and 0·80 concentrate at 0·8 of AL, the DM intakes were 8·2, 9·3, 10·1, 10·1 and 8·0 (s.e. 0·16) kg d?1, respectively, and daily carcass gains were 0·38, 0·48, 0·64, 0·77 and 0·56 (s.e. 0·029) kg d?1 respectively. Increasing the proportion of concentrates in silage‐based diets decreased the concentration of omega‐3 (ω‐3) polyunsaturated fatty acids (PUFA) (P < 0·001) and increased the concentration of ω‐6 PUFA (P < 0·001) in muscle. Cattle on the silage/pasture treatment had the highest concentration of ω‐3 PUFA in muscle (51 g kg?1 lipid), this value being over three times that for animals given diets containing MD silage and 0·80 concentrate in the diet. These results demonstrate the potential of HD silage made from perennial ryegrass relative to high concentrate diets. The consumption of pasture‐finished beef could make a significant contribution towards increasing the intake of ω‐3 PUFA in the human diet.  相似文献   

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