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Item Soil nutrient enrichment in pastoral systems through shelterbelts(Elsevier Ltd, 2025-10-01) Fonseka D; Jha N; Jeyakumar PShelterbelts along pasture boundaries are a natural, cost-effective, and sustainable solution to environmental challenges such as soil degradation and nutrient losses in New Zealand's pastoral systems. However, there's limited information on how shelterbelts affect nutrient dynamics in neighbouring pasture soils. Three field study sites, two dairy farms and one beef and sheep farm, consisting of the same soil type, were selected. Shelterbelts on the sites were composed of Pinus or Macrocarpa, or a mix of Macrocarpa and Willow. Soil samples were collected from each site, both with and without shelterbelts, at three transects for six distances (1 m, 5 m, 10 m, 20 m, 40 m, 80 m) and two soil depths (0–7.5 cm and 7.5–15 cm) in late spring 2023. Shelterbelts on all four farms significantly affected soil nutrient distribution in the adjacent area. Soils within 10 m of shelterbelts had higher total and Olsen phosphorus levels by up to 65 % and 80 %, respectively; the total and nitrate nitrogen levels increased by up to 64 % relative to control (no shelterbelt) soils. Shelterbelts increased soil organic carbon by up to 75 %. The macrocarpa and willow combined shelterbelt deposited around 17 Mg more C in the area tested compared to the control. These findings indicate that the shelterbelt with grazed pastures enhances phosphorus and nitrogen availability within the immediate vicinity. The inclusion of diverse species can contribute to the accumulation of topsoil carbon. Future research should focus on comparing more diverse tree species and improved grazing practices within shelterbelts to enhance the sustainability of the grazing farming system.Item Implications of tree management on poplar and willow pasture-tree systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, Massey University, Palmerston North, New Zealand(Massey University, 2016) Maldonado Garcia, Noel MauricioWillow and poplar trees planted at wide spacing have proved their effectiveness as a biological method to control soil erosion in pastoral hill country. Due to lack of management, many trees aged 30+ years have grown very large (>60 cm diameter at breast height), resulting in excessive shading of understorey pasture. The large trees are also prone to breakage of branches and toppling during strong winds, potentially damaging farm infrastructure or injuring livestock. Management of tree size can coincide with providing edible poplar and willow foliage as a source of supplementary fodder in summer droughts. Trees can be pollarded, involving total canopy removal, but the effects of pollarding on tree root dynamics are poorly understood. This thesis evaluated the effect of the tree canopy removal on the root dynamics and root non-structural carbohydrate dynamics of pollarded mature willow and poplar trees and decapitated young willow and poplar trees grown from cuttings. Impacts of tree canopy removal when trees were at different phenological stages were also studied in pollarded mature willow trees and decapitated young willow and poplar trees. Finally, herbage accumulation under pollarded trees was contrasted with herbage accumulated under unpollarded (UP) trees and in open pasture sites (OP) away from direct tree influence. Pollarding did not impose a unique impact on the root structure of mature willow and poplar trees. However some similarities were found in both species. For instance, pollarding had its main impact in the roots closest to the trunk and above 300 mm soil depth. In these root sections disrupted by pollarding, fine root length and mass of pollarded (P) trees were, one year after above-ground removal, from 2× to 4× less than equivalent unpollarded (UP) trees. However, one year after pollarding, pollarded trees recovered or maintained the initial fine root densities recorded in the same trees prior to pollarding. The study conducted with young willow and poplar trees grown from cuttings showed that willow trees had a greater ability to recover from damage in the root structure after decapitation. Nine months after decapitation in early autumn, root mass of young willow decapitated trees was 57% greater than prior to decapitation and 64% less than non-decapitated (ND) trees. In contrast, within the same time frame, root mass of young poplar trees decapitated in early autumn was 80% less than ND trees and 52% less than the initial root mass recorded prior to decapitation. Greater resprouting ability of willow trees than poplar trees after decapitation was proposed as the cause for the greater resilience to decapitation observed in willow trees than in poplar ones. Further evidence for a greater resilience to pollarding of willow trees was found in the root starch dynamics evaluated after tree canopy removal. Pollarded or decapitated willow trees (mature or grown from cuttings) were able to replenish their root starch concentrations similarly to UP or ND trees in the growing season following tree canopy removal. In contrast, both pollarded and decapitated poplar trees (mature or grown from cuttings) had lesser root starch concentrations than intact trees one year after tree canopy removal. Pollarding (P) or decapitation (D) at dormancy (DP or DD trees) showed no clear advantages in terms of the tree root structure maintenance or recovery after above-ground removal, over pollarding or decapitating the trees towards the end of the growing season in early autumn (AP or AD trees), when trees still had leaves. With mature willow trees, annual average fine root density (fRD) recovery of DP trees relative to pre-pollarding density was greater than annual average fRD recovery of AP trees. However, this difference was attributed to record moisture restrictions that disrupted the root growth of both AP and UP trees during the growing season following early autumn pollarding. Similarly, young DD and AD willow and poplar trees showed that four and a half months after decapitation, both treatment trees were able to recover or maintain initial root mass recorded prior to decapitation. The study on herbage accumulation beneath pollarded trees, suggests that 4 years after being pollarded, P willow trees shaded pasture in a similar way to UP trees, as annual net herbage accumulation (NHA) attained in these two environments was statistically not different. Annual NHA under P and UP environments, were, respectively, 30 and 43% less than annual net herbage accumulation recorded in open pasture sites (4.9 t DM ha-1 yr -1). Ability of willow trees to recover, within the first year after pollarding or decapitation, initial root densities recorded prior to canopy removal, and to replenish root starch concentration similar to intact trees, suggests these trees could have pollarding cycles of 2 to 3 years. Short pollarding cycles could lessen herbage accumulation reductions on a pasture-tree stand level as more trees or more frequent repollarding is practised. However, results derived in this thesis from willow trees, need to be confirmed in at least two year lasting studies before recommending shorter pollarding cycles than currently advised of 3 or 4 years. In contrast, poplar trees require longer pollarding cycles or higher tree stand densities if a pollarding program is instituted, as these trees were not able to recover within the first year after canopy removal, the root values recorded prior to pollarding and/or to replenish the root starch reserves.Item Willow fodder blocks for growth and sustainable management of internal parasites in grazing lambs : a thesis presented in partial fulfilment of requirements for the degree of Master in Veterinary Science at Massey University, New Zealand(Massey University, 2005) Diaz Lira, Carolina MacarenaA rotational grazing experiment was conducted for 14 weeks in the summer/autumn of 2004/2005 on the lower eastern North Island, New Zealand, to compare the efficacy of grazing willow fodder blocks containing condensed tannins (CT), for sustainable control of internal parasites in 180 Suffolk x Romney weaned lambs. One third of the lambs grazed control perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture only, another third grazed pasture for 3 weeks followed by willow fodder blocks for 1 week (repeating the rotation; restricted access) and the last third of the lambs grazed on willow fodder blocks for the duration of the experiment (full access). All lambs were effectively treated with anthelmintics at the start of the experiment. Each group was divided into undrenched lambs and lambs regularly drenched every 4 weeks. Each of the six groups grazed separate areas at the same dry matter (DM) allowance, using rotational grazing with weekly breaks. Undrenched lambs would be trigger drenched if the faecal egg count (FEC) geometric mean of the group exceeded 1000 eggs/g wet faeces and/or liveweight gain (LWG) was reduced to zero and/or any one individual lamb exceeded 2500 eggs/g wet faeces, which never occurred. Rectal faecal samples for FEC, larval counts (LC) and visual dag formation (Dag Score; DS) were assessed initially and at two week intervals throughout the experiment. All lambs were slaughtered at the end of the experiment, fatness (GR) and carcass weight (CW) measurements were recorded and representative samples of the abomasum, small intestine and large intestine were collected in the three undrenched treatments to determine total worm burdens. Primary growth legume content in willow fodder blocks was similar to that of control pasture (20%), but willow fodder blocks secondary growth legume content (30%) was greater than in secondary growth control pasture (22%). Primary growth pre-grazing herbage mass (approximately 4800 kg DM/ha) and post-grazing herbage mass (approximately 3400 kg DM/ha) in willow fodder blocks (full and restricted access) was higher than that of control pasture (4400 and 3000 kg DM/ha respectively). Secondary growth pre and post-grazing herbage mass was similar in willow fodder blocks and control pasture (4200 and 3000 kg DM/ha respectively). Secondary growth mass of fodder trees (775 kg DM/ha) in the willow fodder block full access treatment was higher than primary growth (562 kg DM/ha). Pre-grazing herbage dead matter content was consistently higher in secondary growth (20-40%) than in primary growth (8-10%), for both control pasture and fodder blocks. Condensed tannin concentration in willow fodder block herbage was 14.5 g/kg DM compared to the CT levels (6.2 g/kg DM) detected in control pasture diet selected. However, CT concentration in willow fodder block trees was particularly high (approximately 45.5 g/kg DM). In vitro OMD, DOMD and ME concentrations were higher for selected tree browse in willow fodder blocks (0.71; 0.65 g/kg DM; 10.6 MJ/kg DM respectively) when compared to herbage selected in either willow fodder blocks or control pasture (0.65; 0.60 g/kg DM; 9.7 MJ/kg DM respectively). Regularly drenched lambs had significantly higher LWG and carcass weight gain (CWG) than undrenched lambs (p < 0,05) in all three groups. Lambs in willow fodder block full access had the highest LWG in drenched as well as undrenched lambs of 182 g/day and 154 g/day respectively. Due to hot and dry summer conditions, growth rates of all treatments declined in the second half of the experiment as herbage nutritive value declined. Undrenched willow fodder block full access had the highest CWG amongst all undrenched treatments. Carcass weight gain reduction of undrenched lambs versus drenched lambs for the full access to willow fodder block group (12 g/day) was half of the reduction between control pasture groups (24 g/day). Dag score increased with time until Day 70 of the experiment, with no differences between the six treatment groups. From Day 70 until the end of the experiment, dag scores of lambs grazing willow fodder block full access were consistently lower than lambs grazing willow fodder block restricted access or control pasture and were lower for drenched than for undrenched lambs. Drenched groups maintained low FECs throughout the experiment, whereas FECs of undrenched groups progressively increased with time. Both DS and LWG were similar for drenched lambs grazing control pasture and undrenched lambs grazing willow fodder block full access. The parasites established in greatest numbers in undrenched lambs grazing control pasture were Teladorsagia trifurcata, Nematodirus spathiger, Trichostrongylus vitrinus, Trichostrongylus colubriformis followed by Trichostrongylus axei and Teladorsagia circumcincta. At slaughter, undrenched lambs grazing on willow fodder block full access had significantly lower Nematodirus spathiger, Trichostrongylus vitrinus and Trichostrongylus colubriformis worm burdens when compared to undrenched lambs grazing control pasture (p < 0.05), but greater burdens of Haemonchus contortus (p = 0.0299). Undrenched lambs grazing willow fodder block with restricted access had significantly lower Teladorsagia circumcincta, Teladorsagia trifurcata, Trichostrongylus vitrinus and Trichostrongylus colubriformis worm burdens than undrenched lambs grazing control pasture (p < 0.05). It was concluded that parasitism restricted lamb growth in all three undrenchcd grazing systems, showing a progressive increase in FEC over time. However, the reduction in carcass weight gain was greatest for undrenched control lambs and least for undrenched lambs with full access to willow fodder blocks. Grazing undrenched lambs on restricted and full access willow fodder blocks showed lower burdens of some parasites at slaughter compared to undrenched lambs grazing control pasture, which could be due firstly to an increased CT present in both willow and in fodder block herbage and their possible effects in increasing protein absorption. Secondly, CT could have interrupted parasite life cycles and/or. thirdly, decreased L3 larval consumption could have occurred due to taller plant morphology of the trees, hence reducing the reinfection rate. There seemed to be no direct effect on killing established parasites, as if that had happened, there should have been a decrease in FEC in the first half of the experiment, before any effects of reinfection took place. CT-containing forages could be used in conjunction with live weight gain monitoring and/or body condition score for the control of gastrointestinal nematodes, but it still needs further evaluation and a close collaboration of researchers and farmers.Item The effect of grazing willow (Salix spp.) fodder blocks upon reproductive rate and management of internal parasites in mated hoggets : a thesis presented in partial fulfilment of the requirements for the degree of Master in Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2007) Musonda, KelvinA grazing experiment was conducted for 116 days from 19 January to 15 May in the late summer/autumn of 2006 at Massey University's Riverside dryland Farm, near Masterton (New Zealand) to compare the effect of grazing willow fodder blocks or control perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pasture, during the pre-mating and mating periods, on gastrointestinal parasitism control and reproductive rates in 7 months old ewe hoggets. A rotational grazing system with 348 Romney weaned hoggels was used. Hoggets were randomly allocated to three treatment groups (116/group), being: control pasture with regular anthelmintic drenching, control pasture with trigger drenching (drenched only when mean faecal egg count of each group exceeded 1000 eggs/g wet faeces) and willow fodder blocks with trigger drenching. Four replicated pasture areas and five replicated willow fodder blocks were rotationally grazed by single groups of animals, using animals as the replicates for statistical analysis. The fodder blocks contained small trees and a mixture of herbage growing under the trees. After mating, the three groups were joined together and managed as one group until the end of the experiment at weaning, on 7 January 2007. Hogget live weight (LW), dag scores, faecal egg counts (FEC) and reproductive rate at foetal ultrasound scanning, lambing, docking and weaning were measured. Ewe hogget wool production was measured at weaning. Relative to control pastures, fodder block herbage was of lower dead matter content and its legume content was slightly higher. Total N concentration (35 g/kg dry matter; DM), organic matter digestibility (OMD; 0.68) and metabolisable energy (ME; 10 MJ/kg DM) were similar for fodder block pasture and control pasture; the selected tree fodder had lower concentrations of N (24 g/kg DM) and was higher in OMD (0.74) and ME (10.4 MJ/kg DM). Tree fodder contained higher concentrations of CT (22.9 g/kg DM) compared to 1.6 g/kg DM in control pasture and herbage in willow fodder blocks. Grazing willow fodder blocks increased LWG (approximately 97 g/day vs. 86 g/day; P< 0.0001) and increased reproductive rate corrected to equal LW by approximately 17% units (P<0.05), due to increases in both oestrus activity (P<0.01) and conception rates (hoggets pregnant/100 hoggets mated; P<0.05). Calculated daily DM (1.41 kg) and ME (14 MJ) intake were similar in all groups. Calculated daily CT intake (6.0g vs. 2.1g) and CT intake/100 g CP intake (2.2 g vs. 0.7 g ) was higher for willow fodder block hoggets than for the control pasture groups; this may have increased the flow of undegraded dietary protein (UDP) to the small intestine, leading to increases in reproductive rate of this group. Grazing willow fodder blocks failed to reduce the number of anthelmintic drenches (3) needed to maintain FEC below 1000 epg wet faeces, but was successful in reducing dag score relative to grazing conventional ryegrass/white clover pastures. It was concluded that grazing willow fodder blocks can play a beneficial role in sustainable farming systems as it can sustain animal growth rates, increase reproductive rate and reduce dag formation in parasitized hoggets. These benefits were associated with reduced dead matter content and increased legume content in fodder block herbage and with increased intake of secondary compounds from the trees. However, both pasture and trees need to be managed as a tree/pasture system in order to produce herbage of higher nutritive value and more efficiently utilise willow fodder blocks as a supplementary feed. After 6 years of grazing in this manner, the survival rate of the trees was approximately 85 %Item Growth, management and nutritive value of willows (Salix spp.) and other browse species in Manawatu, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph.D.) in Plant Science at Massey University, Palmerston North, New Zealand(Massey University, 1998) Oppong, Samuel KingsleyPastoral farming in New Zealand depends mainly on the grazing of ryegrass (Lolium perenne) and white clover (Trifolium repens). These pastures yield less during dry summers and farmers are then faced with feed shortages. This study revealed the potential of deciduous willows, Salix matsudana x alba and Salix kinuyanagi as useful supplementary fodder during dry summers. The species can be managed under cut and carry or in situ browsing systems. The use of the Salix spp. as drought fodder is a viable option for pastoral farmers to assist them to overcome pasture feed shortages while maintaining their role in conserving soil. Three experiments were conducted to determine (1) the effects of cutting height and frequency on browse yield and quality of deciduous Salix spp., compared with Dorycnium rectum, a small leguminous shrub and (2) the effects of planting stocks and fertiliser use on the yield and quality of the Salix species. Experiment 1, conducted at HortResearch, Aokautere (10 km from Palmerston North) demonstrated that edible dry matter (DM) yield of the Salix spp. and D. rectum was uninfluenced by stump height and frequency of harvest. S. matsudana x alba outyielded S. kinuyanagi and D. rectum. The in vitro organic matter digestibility (OMD) and nitrogen (N) concentration of the three species were: S. matsudana x alba (670 g kgDM-1 and 21 g kgDM-1), S. kinuyanagi (613 g kgDM-1 and 18 g kgDM-1) and D. rectum (665 g kgDM-1 and 22 g kgDM-1). Experiments 2 and 3 were conducted at AgResearch Grasslands, Ballantrae (25 km from Palmerston North). Experiment 2 showed that unrooted stem cuttings produced as much foliage as rooted stem cuttings, and the former are recommended due to their cheaper establishment. S. matsudana x alba consistently outyielded S. kinuyanagi even though DM yields were lower than at Aokautere. Experiment 3 revealed that DM yields of the Salix species were unaffected by fertiliser application. The low DM yield at Ballantrae may be due to the effects of strong winds and low temperatures. At both Aokautere and Ballantrae, S. kinuyanagi (255 vs. 289 g kgDM-1) had higher total condensed tannin concentrations than S. matsudana x alba (60 vs. 154 g kg DM-1). Two experiments were conducted at AgResearch Grasslands, Palmerston North to determine (1) the leaf lifespan and effect of leaf maturation on leaf quality of the Salix spp. and the legume Chamaecytisus palmensis, (2) the appropriate time to cut the Salix spp. to optimise regrowth and browse quality for summer use, and (3) the changes in non-structural carbohydrate reserves associated with defoliation. The long leaf lifespan of the Salix spp. (6.5 months) and Chamaecytisus palmensis (5.5 months) indicated that the green standing biomass could be retained until needed in summer. The leaves of the Salix species and Chamaecytisus palmensis declined in N concentration and other nutrients at 3 months, which was longer than for those of most herbaceous species (1-2 months) during most times of the year. Leaf N concentration in all three species at each harvest met the recommended level (17 g kgDM-1) for a diet adequate for a lactating ewe rearing a lamb. S. matsudana x alba yielded 70% more DM than S. kinuyanagi when cut in mid-spring. Sucrose comprised over 90% of the total soluble carbohydrate concentration in the roots of S. matsudana x alba defoliated once and three times in the growing season. Two experiments were also conducted at Massey University to determine (1) the effect of browsing intensity and frequency on the regrowth of the Salix spp. and C. palmensis, and (2) sheep preference for these browse species at different times of the growing season. Regrowth of S. matsudana x alba and C. palmensis was similar under heavy or light browsing whereas heavy browsing in S. kinuyanagi increased regrowth in woody stem and total DM yields. S. matsudana x alba was the preferred species. Sheep biting rate, percent time spent browsing species and preference rating of species were higher in summer than autumn for S. matsudana x alba and similar for C. palmensis in both seasons. For S. kinuyanagi, these variables were higher for autumn and almost zero for summer browsing. The two Salix spp. will complement C. palmensis, when grown in moist sites, where Chamaecytisus trees have low survival. The Salix species under proper management will provide useful supplementary feed for livestock during summer.Item The effect of poplar (Populus spp.) and willow (Salix spp.) supplementation on the reproductive performance of ewes grazing low quality drought pasture during mating : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science in the Institute of Veterinary Animal and Biomedical Science, Massey University(Massey University, 2004) McWilliam, Eileen Lee HafnerA series of grazing experiments was conducted, in the summer/autumn of 2001, 2002 and 2003, to investigate the effects of poplar (Populus spp.) and/or willow (Salix spp.) supplementation, during mating, on ewe production and reproduction when grazing drought pasture. Each experiment involved a rotational grazing system with 300 mixed-age Romney ewes, divided into three groups of 100 ewes each. In each year, all ewes were offered low quality simulated drought pasture, containing more than 60% dead matter, at an allowance sufficient to provide a potential desired intake of 0.70 kg dry matter (DM)/day, for periods of 9 to 12 weeks, including two mating cycles. Mean pre-and post-grazing pasture masses averaged over the three years were 1100 and 600 kg DM/ha. The pasture consumed in all years was typical of pasture available to grazing livestock in a drought; it was high in neutral detergent fibre (NDF; approximately 600 g/kg DM), low in organic matter digestibility (OMD, approximately 0.52) and metabolisable energy (ME; approximately 7.5 MJ/kg DM) and contained approximately 20 g nitrogen (N)/kg DM. The supplementary poplar and willow diets were always superior to drought pasture consumed by the ewes, being higher in OMD (approximately 0.67), ME (approximately 10 MJ/kg DM) and total N (approximately 26 g/kg DM) and lower in NDF (approximately 383 g/kg DM). Tree fodder diets also contained substantial concentrations of the secondary compounds condensed tannin (CT; range 7 to 52 g/kg DM), salicin (approximately 2 g/kg DM) and other phenolic glycosides (approximately 21 g/kg DM), with willow (27 to 52 g/kg DM) containing greater concentrations of CT compared with poplar (7 to 19 g/kg DM). Mean diameter of the tree fodder stem consumed during the series of experiments was approximately 7 mm for poplar and 4 mm for willow with the diameter increasing over the experimental periods in four cases out of live (P<0.05). After the supplementation period, the three groups were joined together and grazed on perennial ryegrass/white clover pasture until the conclusion of each experiment at weaning. In all years, the effect of poplar and/or willow supplementation on ewe live weight (LW) and body condition score (BCS) change; the proportion of lambs (reproductive rate) at pregnancy scanning, lambing, docking and weaning; and wool production and staple length from ewe fleeces with approximately 11 months growth, were measured. Experiment 1 was designed to determine how much poplar fodder needed to be fed to increase ewe production and reproduction over a 71-day supplementation period. The experiment involved a high supplementation group, offered 1.5 kg fresh poplar/ewe/day; a low supplementation group, offered 0.75 kg fresh poplar/ewe/day; and a control group that was offered no tree fodder. Ewes in the high and low treatments lost less LW (-67 and -71 vs. -82 g/day; P<0.05) and BCS (-0.78 and -1.27 vs. -1.31 units; P<0.05) compared with unsupplemented ewes. Reproductive rate was relatively low in the control group (121 lambs born/100 ewes mated), with poplar supplementation increasing ewe reproductive rate by approximately 20% units (P<0.05) and 30% units (P<0.001) for the low and high treatment groups, respectively, at scanning, lambing, docking and weaning. The increase in reproductive rate in supplemented ewes was due to increases in both conception rate (number of ewes pregnant/100 ewes mated) and fecundity (number of lambs born/100 ewes mated). Experiment 2 was designed to determine if production and reproduction varied between ewes fed poplar versus willow at the same rate of supplementation, 1.4 kg fresh forage/ewe/day, for 87 days. Again, reproductive rate was relatively low in the control group (133 lambs born/100 ewes mated), with willow supplementation reducing L.W loss (-86 g/day vs. -103 g/day; P<0.01) and increasing reproductive rate by 15%, 17% 21% and 20% units at ultrasound scanning (P=0.097), lambing (P=0.087), docking (P<0.05) and weaning (P=0.058), respectively. The increase in reproductive rate was due to an increase in fecundity; supplementation did not affect conception rate in this experiment. Unlike the previous experiment, poplar supplementation showed no effect on reproductive rate, despite the increase in DM intake and the apparent reduction in LW loss of 9 g/day (P-0.11). It is likely that severe contamination of the poplar fodder with Melampsora larici-populina, or poplar leaf rust, confounded the results. Building on the results of the first two grazing trials, the next step was to determine the period (days) of tree fodder supplementation necessary to achieve a response in reproductive rate. Experiment 3 involved ewes fed 1.3 kg fresh willow/ewe/day for a 'long' period, 63 days including 6 weeks of mating, and a 'short' period, 31 days including 3 weeks of mating. The mating period commenced on the same day for all groups and lasted for 6 weeks. Willow supplementation for 63 days reduced ewe LW loss (-96 g/day vs. -147 g/day; P<0.05) and BCS (-0.79 VS. -1.09; P<0.05) loss, compared with unsupplemented ewes; however, it did not increase reproductive rate at scanning and lambing. The lack of response in willow-supplemented ewes was likely to be due to toxic concentrations of zearalenone (1.5 mg/kg DM), an oestrogenic mycotoxin, in the drought pasture during mating, which confounded the results by negating any potential benefits due to increased nutrient intakes. Willow supplementation for 63 days did increase reproductive rate at weaning by 13% units, due to a 9% unit (P<0.05) reduction in post-natal lamb mortality, from 17.1 to 8.4%. Supplementation for 31 days did not appear to influence ewe reproduction and production parameters. Overall, the rate of LW loss was greater in Experiment 3 compared with the first two experiments. Seven indoor in vivo digestibility experiments were conducted at the following times; early April 2001 (poplar), February, March and April 2002 (all poplar), and December, March and April 2003 (all willow). Each 14-day trial involved 6 male cryptorchid lambs, individually fed in metabolism cages. The experiments showed that the digestibility of poplar and willow tree fodder declined from late spring to autumn (P<0.05), but that the decline was much smaller than the decline in digestibility of grass-based pastures in New Zealand over the same time period. The experiments also showed that mean ME and digestibilities were generally higher for willow than for poplar. The seven in vivo digestibility coefficients were then used to develop a standard curve for in vitro prediction of in vivo digestibility, this standard was used to analyse all unknown tree fodder samples from the three grazing experiments. Results from the three grazing experiments showed that supplementing ewes grazing drought pasture during mating with poplar and willow tree fodder consistently increased DM intake by 0.25 to 0.33 kg DM/ewe/day for ewes offered 1.3 to 1.5 kg fresh willow or poplar each day and increased calculated total DM intakes from 0.67 to 1.03 kg DM/ewe/day in Experiment 1, from 0.59 to 0.86 kg DM/ewe/day in Experiment 2 and from 0.47 to 0.75 kg DM/ewe/day in Experiment 3. Supplementation also consistently reduced LW loss and loss in BCS and substantially increased lambing rate through increased conception rate and fecundity and reduced post-natal lamb mortality. The effects on LW and BCS gradually declined in the post-treatment period and were no longer evident by commencement of lambing. There was no effect of supplementation on wool production or staple length in any of the experiments. One of the unexpected results of the experiments was an average 34% reduction in post-natal lamb mortality over three years, due to willow/poplar supplementation of ewes during mating. Initial results showed that despite significant increases in fecundity in supplemented ewes in 2001 and 2002, post-natal lamb mortality was not increased. This result, combined with a statistically significant reduction in lamb mortality in Experiment 3 (P<0.05), in the absence of any differences in fecundity between the groups, suggested that tree fodder supplementation during mating may have reduced lamb mortality in all three years, but that the effect was masked by the increase in reproductive rate in the first two experiments. Therefore, data from the three field trials were combined and analysed by adjusting all mortality data to equal birth rank and sex; this showed a significant reduction due to supplementation (P<0.05) with no treatment-year interaction. The increase in ewe production and reproduction in supplemented ewes was likely due to increases in nutrient intake, through increased DM, ME and CP intakes, prior to and during mating and to increased outputs of undegradable dietary protein and microbial protein from the rumen, per unit of crude protein consumed, thus increasing amino acid absorption. An increase in ovulation rate of 1.5 % units/MJ of digestible energy consumed (Smith 1985) should result in increases in ovulation rate due to tree fodder supplementation of only 5 and 4% units in 2001 and 2002, respectively; however, the increases in scanning rate were substantially greater at 41 and 16% units. Therefore, it is possible that the majority of the increase in reproductive rate was due to increased essential amino acid absorption, which is consistent with increases found in ewes mated on CT-containing forages such as Lotus corniculatus (Birdsfoot trefoil). Gross margin analyses using actual data from unsupplemented ewes in each of the three grazing trials compared with Riverside Farm's commercial ewes from the same years showed that drought reduced scanning rates by an average of 22.4% and wool production by 20% and that this reduction decreases sheep production income by approximately $14/ewe. Further analysis showed that almost half the cost ($6/ewe) could be recovered by supplementing ewes with tree fodder in a drought. On a whole farm basis this represents $58/hectare cost benefit due to tree fodder supplementation. Fungal contamination was a significant factor in the results obtained in Experiments 2 and 3. In all years, simulated drought pasture contained metabolites of zearalenone and the trichothecenes nivalenol and deoxy-nivalenol, produced by Fusarium fungi, while in Experiment 2 the poplar was severely contaminated with Melampsora larici-populina, or poplar leaf rust. Zearalenone concentrations in pasture were at their greatest in Experiment 3 and increased to over 2 mg/kg DM during the mating period. This may explain the lack of increase in reproductive rate expected in willow-supplemented ewes in Experiment 3, which was a feature of previous experiments; however, it did not explain the much greater loss in ewe LW in Experiment 3. Nivalenol (NIV) and deoxy-nivalenol (DON) are common trichothecene toxins found in New Zealand pasture and were found in pasture samples from all three experiments, however, the concentration in Experiment 3 was three- to four-fold greater than in previous experiments. Reports have suggested that trichothecenes may be partly responsible for the reduced growth of otherwise healthy livestock grazing dry autumn pasture, often referred to as 'ill thrift'. However, based on evidence from dosing experiments, it is unlikely that the quantities of NIV and DON present in pasture in Experiment 3 accounted for all of the greater LW loss seen in this experiment. This suggests that these toxins are likely to be indicators of other more potent fungal toxins, which have a much bigger impact on livestock health and production. It is likely that fungal toxins contribute more to reduced reproduction in breeding ewes and to ill thrift in young stock grazing dry autumn pastures in East Coast regions than is currently acknowledgedItem Environmental effects of densely planted willow and poplar in a silvopastoral system : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (Ph. D.) in Agroforestry, Institute of Natural Resources, Massey University, Palmerston North, New Zealand(Massey University, 2007) Hussain, ZakerNew Zealand, having large areas of hilly landscapes, is subject to the risk of soil erosion, and summer and autumn droughts that limit pasture growth, which in turn affects the livestock-based economy. The nitrogen and phosphorus input in fertilisers coupled with livestock excreta and soil disturbance impose a serious threat to downstream water quality. The planting of trees is one option used to decrease soil erosion, increase the quantity of forage and manage runoff. To date, research has mainly focused on wide spaced poplar trees for feed quality and their effects on understorey pasture growth. However, there is increasing interest in the use of densely planted willow and poplar for fodder purpose. The effects of young (< 5 yrs old) willow and poplar planted at close spacing on runoff, soil erosion, growth of understory pasture and nutrient losses have never been studied in New Zealand. Three field trials (two at Crop and Research Unit, Moginie, Manawatu and one at Riverside Farm, Masterton) were conducted between October 2004 and November 2006 that incorporated comparative establishment and growth of densely planted willow and poplar and their effects on soil moisture, runoff, sediment load and nutrient losses from grazed and fertilised farmland. It was concluded that densely planted willow and poplar (3-4 yrs) reduced total nitrogen (TN) and dissolved reactive phosphorus (DRP) by 47 % each and sediment load by 52 %. Young trees reduced surface runoff and soil moisture more as they aged. However, due to their deciduous nature willow and poplar were not effective in reducing surface runoff in winter and early spring. Sheep preferred camping under trees, especially in late spring and summer, and this led to greater deposition of dung and urine under trees than open pasture. Sheep grazing, especially in winter, significantly increased sediment and nutrient loads in runoff water. The N and P fertiliser application increased nutrient load in runoff water well above the threshold level required to initiate algal growth to create eutrophication. Densely planted willow and poplar significantly reduced understorey pasture growth by 23 % and 9 %, respectively, in their second year at Moginie, mainly due to shade, but coupled with soil moisture deficit in summer. The pasture growth in a willow browse block was 52 % of that in open pasture as a result of shade and differences in pasture species composition. Sheep browsing reduced willow leaf area significantly. Willow and poplar survival rates were similar (P > 0.05) after two years of establishment (100 % vs 90.5 %, respectively). However, willow grew faster than poplar in height (1.90 vs 1.35 m), stem diameter (43.5 vs 32.6 mm), canopy diameter (69 vs 34 cm) and number of shoots (8.7 vs 2.3) at the age of two years, respectively. The research clearly demonstrated that densely planted young willow and poplar trees can reduce runoff, sediment load and nutrient losses from farmland to freshwater, but shade and soil moisture can limit pasture growth under trees. It is recommended that willow and poplar should be planted at wide spacing on the whole farm to minimise loss of pasture. Where blocks of trees are necessary, such as willow browse blocks, sheep browsing can be used as a tool to reduce shade to improve pasture growth. Livestock access to riparian strips should be minimal to avoid livestock camping that can have deleterious effects on water quality.