Herbage Utilization Research Articles

Description and validation of the Teagasc Lamb Production Model

A stochastic budgetary simulation model of a sheep farm was developed to investigate the effects of changes in lamb production systems on farm profitability. Model inputs included: land, labour, capital, animal numbers, as well as, input and output prices. Model outputs were simulated on a monthly basis and included: flock sales and purchases, net energy demand, grass supply and demand, lamb growth and slaughtering pattern, as well as, land and labour utilization. Grass growth, ewe and lamb mortality, fertiliser and concentrate price along with lamb and mutton price were all included in the model as stochastic variables. Farm earnings before interest and tax and net profit, both including and excluding owner/operator labour, were calculated from total receipts from lamb, culled animals and wool less variable and fixed costs. Validation of the model was undertaken by comparing the model outputs to real farm data recorded on 20 Irish commercial sheep farms as well as comparing the model outputs to those of three individual Irish commercial sheep farms. The model outputs were similar to the real farm data indicating that the model provides a realistic representation of actual farm performance, output and profit. To demonstrate potential application of the model, two lambing date scenarios were investigated; a mid-season lambing flock, with a mean lambing date of March 1st and an early lambing flock, with a mean lambing date of January 1st. Both lambing date scenarios had the same farm area, overall herbage utilization, pregnancy scanning rate and number of lambs weaned per ewe joined to the ram, but the early lambing flock had a higher stocking rate (13.23ewes/ha versus 9.46ewes/ha for March 1st lambing) which increased due to the higher proportion of concentrate in the total flock diet compared with March 1st lambing. The annual return on investment (ROI) of the mid-season lambing flock was 0.95% with a net profit of €11,045 excluding owner/operator labour and management. The early lambing system produced a ROI of −0.70% and a net profit of −€4862. When owner/operator labour and management cost were included the ROI was −0.38% with net profits of −€5462 for March 1st lambing and a ROI of −2.46% and net profits of −€26,735 for January 1st lambing.

Defoliation, Shoot Plasticity, Sward Structure and Herbage Utilization in Pasture: Review of the Underlying Ecophysiological Processes

Sward structure affects herbage growth, pasture species dynamics, and herbage utilization. Defoliation management has a major impact on sward structure. In particular, tiller size-tiller density compensations allow for the maintenance of herbage growth. Tiller size and tiller density are determined by several major morphogenetical components. Defoliation affects these morphogenetical components, depending on its frequency and its intensity, through several direct and indirect physiological and environmental processes. Due to the implications of leaf area removal, defoliation has a direct effect on the mobilization of C and N reserves and their supply to growing leaves. In addition, defoliation has an indirect effect on leaf and tiller morphogenesis, due to its impact on the light environment within the canopy as well as plant responses to light signals (blue light, red far red ratio). Defoliation may also in some cases have a direct negative effect on leaf growth by damaging leaf meristems. Understanding the respective role of these various physiological and environmental processes requires studies where defoliation, photosynthetic active radiation and light signals are manipulated independently. Past and recent knowledge on these direct and indirect effects of defoliation on plant morphogenesis are discussed, leading to an overall integrated view of physiological and environmental processes that lead to adaptations of sward structure in response to defoliation management. Major consequences for herbage utilization efficiency are presented.

High pasture allowance does not improve animal performance in supplemented dairy cows grazing alfalfa during autumn–winter

The aim of this study was to assess the effect of three alfalfa pasture herbage allowances on milk yield and composition during autumn–winter grazing season on early autumn calving dairy cows. Eighteen multiparous Holstein dairy cows were assigned to one of three treatments in a 3×3 Latin square design: low herbage allowance (14kgDM/cow; LHA), medium herbage allowance (27kgDM/cow; MHA) and high herbage allowance (41kgDM/cow; HHA). Dry matter disappearance was lower at LHA although remained similar between MHA and HHA (P<0.05). However, as herbage allowance (HA) increased, lower grazing efficiencies (as the proportion of material removed) were registered (P<0.05). Total dry matter intake (DMI; kg/d) was also lowest for LHA and similar between the other two treatments (P<0.05). Milk yield, 4%FCM, milk fat (g/kg) and casein (g/kg) tended to increase from LHA to HHA (P<0.10). Cows at LHA tended to loss weight whilst cows at MHA and HHA had a tendency to increase BW according the season progressed (P<0.10). In summary, managing cows at HHA will allow cows to a slightly increase in individual milk production and BW gain but in detriment of herbage utilization and potentially, milk production per hectare.

Herbage utilisation efficiency of continuously stocked marandu palisade grass subjected to nitrogen fertilisation

Nitrogen fertiliser accelerates plant growth and increases herbage utilisation efficiency in continuously stocked temperate grass swards, indicating greater herbage production and harvest efficiency. There is no similar evidence, however, for tropical pastures. In this study we evaluated the morphogenetic responses, the patterns of defoliation and the efficiency of herbage utilisation of continuously stocked marandu palisade grass (Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. cv. Marandu) maintained at 30 cm by cattle and fertilised with nitrogen. Treatments corresponded to four measures of nitrogen application (0, 150, 300 and 450 kg ha–1), and were assigned to experimental units (1,200 m2 paddocks) according to a randomised complete block design, with four replications. There was a seasonal pattern of variation in the morphogenetic responses and in herbage utilisation efficiency (HUE) characterised by higher herbage growth rates and HUE during late spring and summer. Nitrogen fertilisation increased both leaf appearance and elongation rates (around 60 % between non-fertilised and swards fertilised with 450 kg ha–1, p < 0.05), requiring higher stocking rates (average of 1.6, 2.6, 2.9 and 3.1 Animal Unit (adult animal weighing 450 kg) ha–1 for 0, 150, 300 and 450 kg ha–1, respectively) to maintain the management target. Although the frequency of leaf defoliation increased (with no change in defoliation severity - 56.1 ± 1.88 %), the leaf lifespan decreased, resulting in a similar number of defoliations during the leaf lifespan (average of 0.91 ± 0.069). This resulted in increased HUE only for the 150 kg ha–1 treatment relative to non-fertilisation (37.5, 48.1, 44.0 and 44.5 ± 2.25 % for 0, 150, 300 and 450 kg ha–1 N, respectively), indicating that with nitrogen fertilisation rates above 150 kg ha–1, there are compensatory mechanisms related to morphogenetic responses that buffer changes in utilisation efficiency.

Optimising the interrelationship between intake per cow and intake per hectare

Production and profit in grazed systems remain inherently constrained by the fundamental trade-off between maximising individual herbage intake and pasture utilisation. The primary objective of this paper is to investigate the trade-off between herbage intake per cow and intake per hectare, from the perspective of economic optimisation, for an intensive pasture-based dairy farm in New Zealand (NZ). A detailed optimisation model of a dairy farm is applied, to allow the complex animal–plant–supplement dynamics underlying this relationship to be explicitly considered. Model output confirmed the existence of the fundamental inverse relationship between individual cow intake and herbage utilisation, which arises from the underlying biophysical dynamics within a grazing system, in the context of pasture-based NZ dairy farms. Results indicated that profitable management relies on increasing total pasture eaten (grazing plus pasture silage harvested on farm) through the use of a relatively high stocking rate and moderate levels of pasture intake per cow. Indeed, for 450 kg liveweight cows, optimal pasture intake per cow is 5 t dry matter (DM) per cow for per hectare intakes of 12–16 t DM/ha and 4.5 t DM/cow for a per hectare intake of 17 t DM/ha. Thus, a goal to maximise both individual intake and herbage utilisation in grazing systems is misinformed; it is the latter that is principally important to farm profit. Indeed, seeking to maximise both simultaneously is not possible, and trying to maximise individual intake can impose an enormous cost. However, while high herbage utilisation increases profit, this can also be associated with greater nutrient leaching, reinforcing the importance of considering the environmental impacts of grazing management.

Managing the herbage utilisation and intake by cattle grazing rangelands

Rangelands throughout the world provide clean water, fix solar energy in plants, sequester carbon, and offer recreational opportunities, with other ecosystem goods and services, including food from wild and domestic herbivores. Grazing rangelands with cattle requires constant management to balance the economic sustainability of the farm with other ecological services that rangelands provide. The challenges in management arise from the diversity of the rangeland forage resources at extremely large spatial and temporal scales. To be able to predict the performance of cattle grazing in extensive rangeland environments, estimating herbage intake is paramount because it quantifies energy intake and performance. Nutrient demand is the major driver of herbage intake, and characteristics of the sward and terrain of the landscape dictate how this demand is met. System models that integrate changes in weather patterns and herbage over long periods of time will allow farmers and scientist to monitor changes in herbage mass and utilisation. Dynamic models that include herbage growth components sensitive to weather patterns and animal demands are needed to predict how long-term changes in beef herd management will affect performance and range condition. Vegetation indexes captured across biomes with satellites can accurately quantify the dynamics of aboveground net primary production and changes in nutritional value with confidence. The computer software, PCRANCH, is a program for simulating cow–calf herd dynamics over long periods of time. The models within the PCRANCH software can simulate herbage growth and animal utilisation at large spatial and temporal scales needed for rangeland management and allow ranchers to evaluate the impacts of management on other ecological services. Knowing the long-term impact of management changes on swards enable ranchers to anticipate the ecological and economic benefits of improvements or demonstrate a protection of current ecological services.

Efficient economic and environmental management of pastoral systems: Theory and application

A framework for interpreting profit–environmental trade-offs in pastoral agriculture is introduced, drawing on the concepts of economic and environmental efficiency. The approach provides insights into appropriate policy mechanisms to address the environmental footprint of agricultural production. The framework is applied in the context of nitrogen leaching from pasture-based New Zealand dairy farms. This application identifies that the economic and environmental efficiency of these farms is mainly driven by imported supplement use. Grass-only farming is environmentally-efficient, with greater supplementation generating higher nutrient outflows to waterways. However, profits increase with higher supplementation within a critical range of intensification. Economic efficiency requires low use of supplement to promote herbage utilisation and reduce pasture senescence at low stocking rates, combined with high use of supplement to fill critical feed deficits at high stocking rates. Model output suggests that there exists scope for win/win solutions for private/public agents through improving the conversion of supplement to milk on New Zealand dairy farms. However, the scope to achieve such gains may be restricted in reality, given incentives for intensification, the potential cost of intensive farm planning, and personal barriers to behaviour change.

Non-destructive foliar chlorophyll measurement has the potential to predict crude protein concentration and in vitro ruminal organic matter digestibility in Bracharia decumbens herbage

Quick and accurate estimation of crude protein (CP) concentration and in vitro ruminal organic matter digestibility (IVOMD) of tropical pastures is critical to determine possible nutrient deficits prior to herbage utilization. We, therefore, investigated the potential of a non-destructive hand-held chlorophyll gun (FieldScout CM 1000 NDVI Meter) to predict lignin (sa), acid detergent fiber (ADF), CP concentration and IVOMD of growing Bracharia decumbens Cv. Basilik herbage. The average of five (5) foliar chlorophyll index measurements obtained by a “point and shoot” action from an approximate 40–45° vertical angle prior to harvesting from each sampling unit was recorded. After chlorophyll measurements, herbage samples were cut according to a stratified random sampling design from four differently managed B. decumbens Cv. Basilik pastures to leave an 11cm stubble height. Herbage sampling was synchronized with existing grazing patterns used at the study sites. The respective pastures were sampled at 14 (Brac-14), 28 (Brac-28), 11 (Brac-11) and 13 (Brac-13) days post-grazing. Relationships between chlorophyll indices (CI), pasture CP concentration and IVOMD were best described by simple linear and polynomial models, respectively. Correlation coefficients (r2) between CI and CP and IVOMD ranged from 0.70 to 0.95 and 0.69–0.85, respectively. Chlorophyll index gave the best estimates for CP concentration and IVOMD in Brac-14 and Brac-13 where CCC and R2 was high, and rMSPE and model related errors were very low. Chlorophyll gun indices accounted for 68–90% and 64–78% variance of CP and IVOMD (P<0.05), respectively, in Brac-14 and Brac-13 herbage. Prediction models for lignin (sa) and ADF were inaccurate and unreliable. We conclude that CI measurements have the potential to predict CP content and IVOMD of B. decumbens pastures. However, further calibration studies are needed to test the sensitivity of the chlorophyll gun under different growing conditions and also with pasture herbage that is sufficiently heterogeneous in chemical composition.

Intake, feed conversion efficiency and grazing behaviour of two Holstein cow strains in a pasture-based production system under organic farming in Switzerland

Better efficiency of herbage utilisation by dairy cows even under organic condition needs more attention. Therefore, Holstein-Friesian dairy cows of New Zealand (HNZ) and Swiss origin (HCH) were compared in a pasture-based, seasonal calving system on an organic farm. During the 3-year investigation intake on pasture, feed conversion efficiency, grazing behaviour and physical activity of cows were compared. The HNZ were lighter (521 vs. 608 kg, P < 0.001) and showed a higher body condition score (2.9 vs. 2.6, P < 0.001) compared to HCH. Furthermore, the HNZ produced less energy-corrected milk (18.2 vs. 21.3 kg/day/cow, P < 0.001) and had a lower total intake than HCH (14.6 vs. 16.7 kg dry matter (DM)/day/cow, P < 0.001). No differences occurred between strains concerning herbage intake (13.0 vs. 12.8 kg DM/100 kg body weight (BW)0.75/day, P = 0.50) and total intake (13.4 vs. 13.6 kg DM/100 kg BW0.75/day, P = 0.52) relative to the metabolic body weight as well as for the short-term feed conversion efficiency (1.29 vs. 1.34 kg/kg, P = 0.22). Cows of both strains grazed equally long (571 vs. 582 min/day, P = 0.25). The HNZ ruminated longer (507 vs. 474 min day−1, P < 0.001) than HCH. No differences were found between strains regarding the number of rumination boli (577 vs. 556/day, P = 0.34) and of mastications per rumination bolus (60 vs. 59, P = 0.66). Further, no differences occurred concerning physical activity. Pertaining to grazing around dung patches, no differences were observed between strains. Striking differences in grazing behaviour were not observed, except prolonged rumination per day for HNZ, but this had no apparent effect on the feed conversion efficiency.

Does post‐grazing sward height influence sward characteristics, seasonal herbage dry‐matter production and herbage quality?

AbstractExtending the grazing season through the production and utilization of high‐quality forage is a key objective in grassland‐based dairy production systems. Grazing swards to a low post‐grazing sward height (PGSH) is a strategy for improving grass utilization. A grazing experiment conducted in Ireland investigated immediate and subsequent effects of PGSH on sward production, utilization and structural characteristics. Swards were grazed to 2·7 cm (severe; S1) or 3·5 cm (moderate; M1) from 10 February to 18 April 2010 (Period 1; P1). From 19 April, each P1 paddock was halved and grazed to either 3·8 cm (S2) or 4·8 cm (M2), until 30 October (Period 2; P2). The first grazing rotation was +7 d on S1 swards compared with M1 swards (45 d), due to greater herbage utilization (+0·22). Herbage production during P1 was not affected by PGSH but a severe PGSH during this period reduced subsequent herbage production: 13·9 (S1) vs. 15·5 t dry matter (DM) ha−1 (M1) by the end of the study. Leaf proportion was increased (+0·10) on S2 swards compared with M2 swards, but M2 swards produced 1·2 t DM ha−1 more herbage during P2. Despite the relatively lower level of sward utilization obtained from moderate grazing in P1 (3·5 cm) and P2 (4·5–5·0 cm), such levels of PGSH increased DM production while maintaining sward quality, compared with severe grazing (2·7 cm in P1 and 3·5–4·0 cm in P2).

Cattle habitat selection and associated habitat characteristics under free-range grazing within heterogeneous Montane rangelands of Alberta

The integration of multiple uses on public rangeland requires reliable information on patterns of livestock use. We used GPS data and field plot utilization indices to examine cattle selection at the landscape and patch levels, respectively, within a heterogeneous Montane environment of SW Alberta, Canada. We also evaluated factors associated with patterns of summer cattle use, including topographic features, distance to water and roads, as well as forage quantity and quality. Cattle preferred lowland and upland grasslands, while avoiding conifer forests and clear cuts. Selection patterns differed markedly between the landscape and plot scales. At the landscape scale, forage use was related to abiotic factors, primarily slope (β=−0.70) but also distance to water (−0.34) and distance from roads (+0.21). The negative impact of slope was greater than that observed in previous studies, and has implications for identifying primary ranges and deriving sustainable carrying capacities in Montane landscapes. At the plot (feeding patch) scale, forage use was additionally related to biomass availability (β=+0.58), and to a lesser extent crude protein concentration (+0.16), highlighting the importance of forage characteristics in regulating cattle use. Lowland grasslands had the highest biomass and received the greatest forage use (43% utilization). Low visitation (44% of plots) and associated forage use (3% herbage utilization) by cattle within cut blocks, combined with conservative forage use across all habitats (3–43%), indicate grazing by cattle is consistent with maintaining other uses within this area, including riparian function, native grassland conservation and forest management.

The effect of stocking rate and calving date on grass production, utilization and nutritive value of the sward during the grazing season

AbstractA 2‐year whole‐farm system study compared the accumulation, utilization and nutritive value of grass in spring‐calving grass‐based systems differing in stocking rate (SR) and calving date (CD). Six treatments (systems) were compared over two complete grazing seasons. Stocking rates used in the study were low (2·5 cows ha−1), medium (2·9 cows ha−1) and high (3·3 cows ha−1), respectively, and mean CDs were 12 February (early) and 25 February (late). Each system had its own farmlet of eighteen paddocks and one herd that remained on the same farmlet area for the duration of the study. Stocking rate had a small effect on total herbage accumulation (11 860 kg DM ha−1 year−1), but had no effect on total herbage utilization (11 700 kg DM ha−1 year−1). Milk and milk solids (MS; fat + protein) production per ha increased by 2580 and 196 kg ha−1 as SR increased from 2·5 to 3·3 cows ha−1. Milk production per ha and net herbage accumulation and utilization were unaffected by CD. Winter feed production was reduced as SR increased. Increased SR, associated with increased grazing severity, resulted in swards of increased leaf content and nutritive value. The results indicate that, although associated with increased milk production per ha, grazed grass utilization and improved sward nutritive value, the potential benefits of increased SR on Irish dairy farms can only be realized if the average level of herbage production and utilization is increased.

A review of the role of excess soil moisture conditions in constraining farm practices under Atlantic conditions

AbstractThe Less Favoured Area (LFA) scheme is a major element of the EU Rural Development Policy, aimed at supporting farming in areas with natural handicaps or low soil productivity. It has been in place since 1975 and accounts for 14% of total Community funding. In 2003, the European Court of Auditors recommended that the socio‐economic criteria on which the current scheme is based be replaced by biophysical criteria. Reviews of the proposals suggest that in Atlantic climates of Northwest Europe, the new criteria do not delineate adequately areas where agricultural productivity is constrained by the biophysical environment and that such areas are instead demarcated by the occurrence of excess soil moisture conditions. In this paper, we review the impact of excess soil moisture conditions on the sustainability of farming systems and their role in constraining strategic and tactical farm management practices. In particular, we review the scientific evidence on the impact of excess soil moisture conditions on herbage growth, herbage utilization, farm operations and environmental sustainability. On the basis of this, we propose an additional biophysical criterion for the new delineation of LFAs, namely the length of time that soil water is in excess of field capacity (‘field capacity days’). While there is no clear threshold for field capacity days above which agricultural sustainability is acutely constrained, the evidence reviewed in this paper suggests that the sustainability of intensive livestock farming and tillage systems is particularly challenging in scenarios where the 80 percentile of field capacity days exceeds 220–230 days.

Effect of pasture allowance and cows’ lactation stage on perennial ryegrass sward quality, pasture dry matter intake and milk performance of Holstein-Friesian cows

Efficient exploitation of grass for cattle requires the application of appropriated grassland management strategies to maximize pasture dry matter intake (PDMI) while maintaining high sward quality by allocating cows to an adequate pasture allowance (PA). The aim of this study was to investigate the effect of two PA, low (L) vs. high (H), on sward quality, PDMI and milk performance of Holstein-Friesian cows (n=72) at two lactation stages (LS), early (E) vs. middle (M). Cows were randomly assigned to four groups (LE, LM, HE and HM) in a 2×2 factorial design. The low PA treatments completed 5 rotations, with more grazing days (+13), lower pre- (14.3) and post-grazing (5.3) sward heights (cm) and higher herbage utilization (81.7%). The low PA had higher stocking rate than the high PA treatments (4.8 vs. 3.9 cows ha-1)and lower PDMI (13.4 kg vs. 14.4 DM cow-1 day-1) with higher (p&lt;0.05) (g kg-1 DM) protein (149.1), carbohydrates (166.7) and digestibility (746.8) while lower (p&lt;0.05) DM (18.4%), acid (283.5) and neutral detergent (508.6) fibers (g kg-1 DM). Sward quality is deteriorated (p&lt;0.05) from rotation 1 to 5, lower decrease was found on low PA treatments. Milk yield (MY) was higher (p&lt;0.05) in cows at early LS (24.8 kg cow-1 day-1), with the lowest (p&lt;0.05) protein (28.9) and fat (36.9) content (g kg-1). No differences were found on MY between PA treatments, but higher protein and fat content were observed on low PA. Decreasing PA resulted in higher sward and milk quality without penalizing MY.

Effects of stocking rate, supplementation, genotype and their interactions on grazing dairy systems: a review

The main effects of, and the interactions between, stocking rate (SR), supplementation and genotype on dry matter (DM) intake, herbage utilisation, milk production and profitability of grazing dairy systems have been reviewed. The SR determines the average herbage allowance (HA) per cow and therefore has a major effect on herbage intake (HI) and on the productivity of grazing dairy systems. In this review, the effect of HA on HI is presented separately for two groups of studies: those that measured allowance at ground level and those that measured allowance at a cutting height of 3–5 cm above ground level. HI and milk yield per hectare usually increase as SR increases. However, there is generally an associated reduction in HI and milk yield per cow because of the decrease in average HA at a higher SR. The dual objectives of adequate level of feeding per cow and high herbage utilisation per hectare can be achieved through the inclusion of supplements. The milk response to supplements depends mainly on the size of the relative energy deficit between potential energy demand and actual energy supply. The relative energy deficit determines both energy partitioning within the cow and substitution rate. The relative energy deficit is increased by either a high demand for energy within the cow or by a deficit of dietary energy available to meet the demand. Cows of different genotype differ in their potential for milk yield. Cows with high genetic potential for milk yield undergo higher relative energy deficits under grazing dairy systems, resulting in lower substitution rates, higher milk responses to supplements, but also lower body condition score, which, in turn, leads to lower reproductive performance. Whole-farm experiments in many countries have demonstrated that the inclusion of supplements, with a concomitant increase in SR, can have synergistic effects in improving the productivity of grazing dairy systems. Overall, the level of supplementation required per cow and the optimum SR depend on the genetic potential of the cow, the size of the responses to supplement, the value of milk and the costs of feeding supplements.

Effect of cultivation of clover based grassland on N losses to groundwater on a clay-loam soil

Herbage utilisation is of primary importance to grassland farmers due to its strong association with profit, yet it is not assessed in routine grass evaluations. On commercial grassland farms, grazing efficiency of varieties is believed to influence their level of herbage utilisation. To understand grazing efficiency the interaction between plant and animal is critical; mechanically simulated grazing protocols are limited in the information they provide. The objective of this paper was to further understand the grazing efficiency of perennial ryegrass varieties by identifying grazing traits which can be used as selection criteria by breeders striving to develop varieties with improved herbage utilisation. Fifty-five perennial ryegrass varieties, both diploid and tetraploid with intermediate and late heading dates, were sown in plots (3 m × 7 m; 21 m2) following a randomised block design with three replicates per variety. Swards were rotationally grazed by lactating dairy cows during the 2015 and 2016 grazing seasons. Sward structural, morphological, and chemical characteristics were measured and related to grazing efficiency, as measured by post-grazing sward height. These data were analysed using the PROC MIXED procedure to test the fixed effects of traits and the GLM procedure to test their relationships with grazing efficiency. Varieties were shown to differ in their level of grazing efficiency (p < 0.001). Tetraploid varieties had significantly (p < 0.001) greater grazing efficiency than diploids recording post-grazing sward heights of 3.8 and 4.1 cm, respectively. Increased free leaf lamina (p < 0.001), tiller mass (p < 0.05) and dry matter digestibility (p < 0.01) were shown to significantly improve grazing efficiency of varieties. This study has identified free leaf lamina, tiller mass and dry matter digestibility as key selection criteria for plant breeders to base their developments upon if grazing efficiency is imported into their breeding programmes.

Yields, Quality and Suitability of Four Annual Forages for Deer Pasture in North Central Alberta

Field pea (Pisum sativum), canola (Brassica napus), turnips (Brassica rapa) and Berseem clover (Trifolium alexandrinum) were grown in north central Alberta to assess their potential yield and quality and to evaluate their utilization and preference by white-tailed deer. Herbage DM yield, crude protein (CP), neutral detergent fiber (NDF), absolute and relative herbage utilization, and dietary preference were the criteria used. The four annual forages produced over 3, 000 to 11, 000 kg ha-1 DM with canola and turnips producing higher DM yields than field pea and berseem clover. Forage CP for the four seeded forages ranged from 140 to 305 g kg-1 DM with canola and turnips having higher CP concentrations than field pea and berseem clover. NDF concentrations ranged from 246 to 480 g kg-1 DM and were lowest in turnips, intermediate in field pea, and highest in canola and berseem clover. Absolute herbage utilization remained similar (P&gt;0.05) among the four forage species. In contrast, relative herbage utilization was greater from berseem clover (66% DM) than field pea (42% DM) or canola (22% DM) or turnips (20% DM). Differences in dietary preference occurred among the four forages (berseem clover ≥ field pea ≥ turnips ≥ canola). These results suggest that annual forages, especially berseem clover and field pea, show promise for increasing forage yield and quality and suitability for late season grazing.

Performance and dietary preferences of white-tailed deer grazing chicory, birdsfoot trefoil or alfalfa in north central Alberta.

Little information exists on the performance of deer on alternative forage species in northern temperate environments during summer and fall, the period of inherent maximum growth in deer. In performance and choice experiments, we compared live weight gain (g/kg(0.75)/day), absolute [kg/ha dry matter (DM)] and relative (% DM) herbage utilization, relative preference index (RPI) as well as plant community visitation of white-tailed deer grazing alfalfa (Medicago sativa), birdsfoot trefoil (Lotus corniculatus) or chicory (Cichorium intybus) in north central Alberta, Canada. Herbage phytomass and quality was also measured on the grazed pastures. Alfalfa had higher dry matter yields and crude protein concentrations than chicory and trefoil. Chicory had lower neutral detergent fiber concentrations than the other forages. Tannin concentrations were greatest in birds foot trefoil (nearly 55 g/kg DM), well above those in the other forages (<5 g/kg DM). Live weight gain was similar among deer feeding within the paddocks seeded to birds foot trefoil and chicory, and more than two times higher (p < 0.05) than deer feeding in paddocks seeded to alfalfa. Deer spent more grazing time (about 40%) on chicory pastures than on alfalfa and birds foot trefoil pastures. RPI values were greatest for birds foot trefoil at 2.11, intermediate for chicory at 1.40, and lowest for alfalfa at <0.60. Absolute herbage utilization remained similar (p > 0.05) among the three forage species. In contrast, relative herbage utilization was greater from birds foot trefoil (52% DM) than chicory (40% DM) or alfalfa (25% DM). These results suggest that the use of alfalfa with other alternative forages may prove beneficial to deer production, rather than using alfalfa pasture alone.

How does protein supplementation affect the selectivity and performance of Charolais cows on extensively grazed pastures in late autumn?

AbstractManagement of beef cows grazing extensively grazed semi‐natural pastures in temperate regions in late autumn can require supplements to be offered. The effects of supplementation with soya bean meal on the diet selected by Charolais cows and on their subsequent performance were examined for an 8‐week period in late autumn in 2 years. Three groups of eight cows were compared: non‐supplemented dry cows (D), non‐supplemented (L) and supplemented (LS) lactating cows. The amount of soya bean meal supplement offered per cow was 250 g d−1 in year 1 and 800 g d−1 in year 2. Dietary choices were measured by direct observations and herbage intake was estimated in year 2. Supplementation affected neither diet selection (L: 0·42 vs. LS: 0·43 for the proportion of bites on green patches in year 1; 0·24 vs. 0·22 in year 2) nor daily organic matter intake of herbage (L: 15·6 vs. LS: 15·9 kg d−1), which may have resulted from an adequate crude protein concentration of herbage. The higher total dry matter intake by cows offered the supplement reduced losses in live weight (L: −1212 vs. LS: −828 g d−1; P &lt; 0·01) rather than increased milk production (L: 5·1 vs. LS: 5·0 kg d−1). This may be linked to the low milk yield potential of the Charolais cows. The use of lactating cows rather than dry cows for pasture management in late autumn would increase the utilization of herbage but a reduction in liveweight losses of cows by supplementation is unlikely to be economic.

Factors influencing tissue turnover during winter in perennial ryegrass‐dominated swards

AbstractDespite low net grass growth rates in Ireland between mid‐November and February, tissue continuously turns over as new leaves are produced and older leaves senesce. The effects of closing swards from grazing on three dates in autumn (1 September, 20 September and 10 October) on tissue turnover in a perennial ryegrass sward during the winter were examined at two sites in the north‐east and south of Ireland. Leaf extension and senescence rates were greater in the south than in the north‐east, and were greatest on the earliest closing date at both sites. Leaf appearance and extension rates at both sites were closely correlated with accumulated daily air temperature above 6°C and mean soil temperature. Site‐specific factors also influenced tissue flux, possibly including grazing intensity at closing and density of tillers of perennial ryegrass. Swards in the autumn with high herbage masses [&gt;2000 kg dry matter (DM) ha−1 approximately] and high leaf area index (LAI; about 2·5 and above) had the greatest leaf senescence rates and the greatest declines in herbage mass during the winter. Leaf senescence rates per tiller in high LAI swards were correlated positively with amount of leaf per tiller and also the proportion of green leaf in the second youngest expanding leaf lost to senescence. As potentially a complex of interactive factors influences tissue flux in winter, it is proposed that the data from this study be used in conjunction with other data to construct a dynamic model to predict more reliably optimum closing date in autumn for herbage utilization in winter.