No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Chicory (Cichorium intybus L.), a valuable forage for ruminant livestock in temperate regions, appears highly degradable in the rumen. Fundamental reasons for the rapid breakdown of chicory cell walls in the rumen were studied. Cell walls were isolated from laminae and midribs of chicory (cv. Grasslands Puna II) leaves. The walls, which, except for the walls of xylem tracheary elements in vascular bundles, were non-lignified, were fractionated progressively with 50 mM CDTA, 50 mM Na2CO3, 1 M KOH, 4 M KOH, 4 M KOH + 3.5% H3BO3, and hot water. The polysaccharides were similar to those in nonlignified walls of other dicotyledons, but with high proportions of pectic polysaccharides (67% of the total wall polysaccharides in the laminae). These included homogalacturonans (HGs, 50% of the total wall polysaccharides in laminae) and rhamnogalacturonan I (RG I). In contrast, the proportions of cellulose, xyloglucans, heteroxylans and glucomannans were low. The locations of different pectic polysaccharides were determined using the monoclonal antibodies JIM5 and JIM7 against HGs with low and high degrees of methyl esterification, respectively, LM6 against arabinan and LM5 against galactan. All primary walls were labelled with all the antibodies used. However, the middle lamella, tricellular junctions and the corners of intercellular spaces were labelled with JIM5 and JIM7, but not with LM5. The middle lamella was labelled with LM6, but not the corners of intercellular spaces. These results support the involvement in cell adhesion of HGs with low degrees of methyl esterification. A preparation of endopolygalacturonase (endo-PG) was used to investigate cell adhesion, and its effect on forage particle breakdown was determined using weight loss, chemical analysis and immunofluorescence labelling. The preparation dramatically reduced particle size. Cell separation was accompanied by a loss of HGs with low degrees of methyl esterifcation from the middle lamella and corners of intercellular spaces. A consequential loss of cell adhesion evidently caused leaf breakdown. The degradation of fresh chicory leaves by rumen bacteria was investigated by measuring weight loss, monosaccharide release and immunocytolabelling. Two bacteria, the pectolytic Lachnospira multiparus D32 and the cellulolytic Fibrobacter succinogenes S85, effectively degraded chicory. Pectic polysaccharides were degraded faster than other wall polysaccharides, with uronic acid released faster and more completely than neutral monosaccharides. The preponderance of non-lignified primary walls and abundance of pectic polysaccharides may account, in part, for the rapid degradation of forage chicory in the rumen. The HGs in the middle lamellae and corners of intercellular spaces probably have a role in cell adhesion, and their degradation is probably responsible for the rapid reduction in the particle size of chicory leaves in the rumen.

Content removed due to copyright restrictions: Burggraaf, V.T., Kemp, P.D., Thom, E.R., Waghorn,G.C., Woodfield, D.R. & Woodward, S.L. (2004) Performance of dairy cows grazing white clover selected for increased floral condensed tannin. Preliminary report from experiments presented in Chapter 4 published in the 2004 Proceedings of the New Zealand Grassland Association. / Legumes containing 20 to 40 g of condensed tannin (CT) per kg of dry matter (DM) can improve dairy cow milk production by reducing ruminal protein degradation to ammonia and preventing bloat. White clover (Triflium repens L.) produces CT in its flower heads. High tannin (HT) white clover, bred for increased flowering and increased floral CT concentration, was evaluated under dairy grazing in Hamilton, New Zealand. Its performance in monoculture was compared to that of Grasslands Huia white clover over two years, and five short-term grazing experiments determined its effects on Friesian dairy cows. Huia and HT had similar floral CT concentrations, ranging from 15 to 77 g/kg DM over two flowering seasons. HT clover had higher flower densities than Huia until the second summer after sowing, resulting in higher clover (leaf plus flower) CT concentrations. Clover CT peaked at 12.1 g/kg DM for HT and 5.7 g/kg DM for Huia. HT swards had lower stolon growing point densities than Huia swards and annual DM yields averaged 10.0 and 11.0 t DM/ha for the respective clovers. The ingress of non-sown white clover genotypes reduced treatment differences in the last 10 months of the experiment. Mild bloat occurred in cows grazing both clovers. Cows grazing HT white clover had rumen ammonia concentrations 5 to 26% lower than that of cows grazing Huia, indicating less proteolysis in the rumen of HT cows, but there were no consistent effects on rumen soluble protein or volatile fatty acids (VFA). Differences between treatments in dietary CT concentrations were too small to affect milk production or composition. Minced mixtures of 0, 25, 50, 75 or 100% of DM as white clover flower with the remainder as white clover leaf, were incubated in vitro and rumen metabolite concentrations determined at 0, 2 ,4, 8, 12 and 24 hours. Polyethylene glycol was added to one of the 50% flower treatments to inactivate CT. Clover flowers had less soluble protein than leaves at 0 hours, and increasing the percentage of flowers from 0 to 100% reduced the net conversion of plant-N to ammonia-N from 29 to 12%. The contribution of CT to these effects was small. Increasing percentages of clover flowers did not significantly affect total VFA production but increased acetate to propionate (A:P) ratios. White clover CT decreased A:P ratios. In another in vitro experiment perennial ryegrass leaf (Lolium perenne L.) was incubated either alone or with white clover flowers or birdsfoot trefoil (Lotus corniculatus L.). Clover flowers were more effective at reducing proteolysis than birdsfoot trefoil, due largely to less release of soluble protein, but birdsfoot trefoil treatments had the lowest A:P ratios. In conclusion, HT clover had higher forage CT concentrations than Huia because of increased flowering. Increased flowering reduced the agronomic performance of HT and lowered rumen ammonia concentrations, but did not increase milk production or prevent bloat. White clover flowers reduced rumen proteolysis in vitro, but this was mainly a result of their low protein concentration. White clover CT and birdsfoot trefoil forage benefited the molar percentages of VFA, but increasing the proportion of clover flowers did not. Further increases in white clover CT concentrations may benefit ruminant performance, but this should not be implemented through increased flowering.

Content removed due to copyright restrictions: Burggraaf, V.T., Kemp, P.D., Thom, E.R., Waghorn,G.C., Woodfield, D.R. & Woodward, S.L. (2004) Performance of dairy cows grazing white clover selected for increased floral condensed tannin. Preliminary report from experiments presented in Chapter 4 published in the 2004 Proceedings of the New Zealand Grassland Association. / Legumes containing 20 to 40 g of condensed tannin (CT) per kg of dry matter (DM) can improve dairy cow milk production by reducing ruminal protein degradation to ammonia and preventing bloat. White clover (Triflium repens L.) produces CT in its flower heads. High tannin (HT) white clover, bred for increased flowering and increased floral CT concentration, was evaluated under dairy grazing in Hamilton, New Zealand. Its performance in monoculture was compared to that of Grasslands Huia white clover over two years, and five short-term grazing experiments determined its effects on Friesian dairy cows. Huia and HT had similar floral CT concentrations, ranging from 15 to 77 g/kg DM over two flowering seasons. HT clover had higher flower densities than Huia until the second summer after sowing, resulting in higher clover (leaf plus flower) CT concentrations. Clover CT peaked at 12.1 g/kg DM for HT and 5.7 g/kg DM for Huia. HT swards had lower stolon growing point densities than Huia swards and annual DM yields averaged 10.0 and 11.0 t DM/ha for the respective clovers. The ingress of non-sown white clover genotypes reduced treatment differences in the last 10 months of the experiment. Mild bloat occurred in cows grazing both clovers. Cows grazing HT white clover had rumen ammonia concentrations 5 to 26% lower than that of cows grazing Huia, indicating less proteolysis in the rumen of HT cows, but there were no consistent effects on rumen soluble protein or volatile fatty acids (VFA). Differences between treatments in dietary CT concentrations were too small to affect milk production or composition. Minced mixtures of 0, 25, 50, 75 or 100% of DM as white clover flower with the remainder as white clover leaf, were incubated in vitro and rumen metabolite concentrations determined at 0, 2 ,4, 8, 12 and 24 hours. Polyethylene glycol was added to one of the 50% flower treatments to inactivate CT. Clover flowers had less soluble protein than leaves at 0 hours, and increasing the percentage of flowers from 0 to 100% reduced the net conversion of plant-N to ammonia-N from 29 to 12%. The contribution of CT to these effects was small. Increasing percentages of clover flowers did not significantly affect total VFA production but increased acetate to propionate (A:P) ratios. White clover CT decreased A:P ratios. In another in vitro experiment perennial ryegrass leaf (Lolium perenne L.) was incubated either alone or with white clover flowers or birdsfoot trefoil (Lotus corniculatus L.). Clover flowers were more effective at reducing proteolysis than birdsfoot trefoil, due largely to less release of soluble protein, but birdsfoot trefoil treatments had the lowest A:P ratios. In conclusion, HT clover had higher forage CT concentrations than Huia because of increased flowering. Increased flowering reduced the agronomic performance of HT and lowered rumen ammonia concentrations, but did not increase milk production or prevent bloat. White clover flowers reduced rumen proteolysis in vitro, but this was mainly a result of their low protein concentration. White clover CT and birdsfoot trefoil forage benefited the molar percentages of VFA, but increasing the proportion of clover flowers did not. Further increases in white clover CT concentrations may benefit ruminant performance, but this should not be implemented through increased flowering.

Early in 1962 the Forest Research Institute of the New Zealand Forest Service became aware that stands of second crop Pinus radiata (D. Don) on some areas of the Moutere Gravel formation were showing slow growth and had a chlorotic appearance (Fig. 1.1). The second crop followed clear felling of mature P. radiata trees and were aged from 0 to 15 years (stone and Will, 1965). It was felt that the apparent reduced growth of the second generation had much in common with similar productivity decline reported especially in European forestry literature. Stone and Will (1965) postulated that the immediate cause o£ the decline was a deficiency of nitrogen highlighted by the low levels of nitrogen in the leaves of the second crop trees, especially those growing on ridge sites. Numerous field trials have been laid out but many of the trials were poorly designed and consequently could not provide statistically sound results. However, some indication of nutrient deficiencies which occur on the Moutere Gravels were obtained. Even before these trials were laid down nutrient deficiencies had been highlighted by early attempts at farming. It was the partial failure of these crops that initially led to the planting of exotic pines, in the belief that these trees thrived on a limited supply of nutrients. The first crop of pines generally fulfilled expectations but nutrient deficiencies started to appear in extensive areas of the second crop. Accordingly, the Forest Research Institute made available three scholarships to study different aspects of the problem. Work was started on a study of the soil sequence across the Moutere Gravels to determine if there was a general decline in fertility of tho soil with the age of the soil and the environmental factors, such as climate which differs in the high inland areas and the low seaside areas of the Moutere Gravels, rather than a particular decline in fertility induced by the first crop of P. radiata. In another study the major weed species Ulex europaeus and Cytisus scoparius was studied to see if its value as a nitrogen fixer would outweigh its disadvantages as a silvicultural weed. Thirdly, a study of the microbial ecology of the soils was undertaken. Whyte (1966) reported that the second rotation trees started to increase their growth rate after approximately five years to a level paralleling the estimated growth rate of the first crop. It was postulated that the residues (needles, roots and branches) remaining after clear felling could cause an increase in microbial numbers and activity with a consequent immobilization of mineral nutrients which were not initially very plentiful. For this reason an area in Tasman Forest was selected in which mature trees and regeneration up to nine years old were found together to study microbial activity and numbers, energy dissipation and nitrogen dynamics to determine if immobilization of nutrients was causing the apparent declines.