Massey Documents by Type
Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294
Browse
4 results
Search Results
Item Yields and quality components of maize hybrids for silage : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Agronomy at Massey University(Massey University, 1996) Villaver, Ronaldo C.Seven maize hybrids were evaluated at Frewens Block, Massey University, Palmerston North to determine the effects of hybrid and plant population on yield and yield components, nutritive value, dry matter (DM) partitioning and N%. The range of maturity of the seven hybrids varied from early to full season. The seven hybrids were P3902, Janna, CF1, Furio P3751, P3585 and CG900 each planted at 75,000; 100,000 and 140,000 plants/ha. Plant height, leaf number and yield were measured at 50% silking. Three subsequent samples were taken for estimation of yield, the final yield being at 30-35% whole crop dry matter %. "In Vitro" Digestibility and Kjeldahl N analysis was done by Animal Nutrition Laboratory, Massey University on the grain, leaf, stem and husk components for the 100,000 plants/ha population only. The effect of hybrid on crop development was closely related to relative maturity. P3902 and Janna, both early maturing hybrids were quickest to reach 50% silking and blacklayer, followed by medium (CF1, P3751, Furio) and late maturing (CG900, P3751) hybrids. Heat unit accumulation of each hybrid followed a similar pattern. Plant height and leaf number differed significantly among hybrids and was related to maturity ranking. Hybrid CF1 achieved the highest (20,046 kg/ha) whole crop DM yield at final harvest while Janna produced the lowest (15,776 kg/ha) yield. The 75,000 plants/ha plant population yielded significantly less than 100,000 and 140,000 plants/ha. There was no difference between the 100,000 and 140,000 plant populations. This study confirmed the present recommended plant population of 100,000 plants/ha for maize silage. Dry matter partitioning at final harvest revealed the highest proportion in the grain component followed by the stem, husk and leaf. Total metabolizable energy (ME) content ranged from 11.3 MJME/kg DM to 10.28 MJME/kg DM. The ME content of CF1 was significantly higher than all other hybrids. Final yield was not correlated with the relative contribution to yield in any of the components or with N % in the crop. However, total metabolisable energy content was correlated with its ME components in the grain, leaf, husk and stem. There were no significant hybrid differences in whole crop N % which ranged from 1.07 to 1.16%. Nitrogen % of total DM was strongly correlated to N% in the grain and moderately correlated to N % in the stem and in the leaf. NHI was highly correlated with % grain. CF1 was the best performing hybrid, having highest yield, metabolizable energy and N %. However, among six commercial maize silage hybrids (CF1 is excluded being a non-commercial hybrid at the time of experiment) tested, P3902, Furio, P3585 are the preferred hybrids for early, medium and full season, respectively. The performance of CF1 suggests that there is considerable potential for improving the agronomic characteristics of maize hybrids for silage production in New Zealand through local plant breeding programmes.Item Whole grain inclusion in poultry diets : effects on performance, nutrient utilisation, gut development, caecal microflora profile and coccidiosis challenge : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Institute of Veterinary, Animal and Biomedical Sciences (IVABS), Massey University, Palmerston North, New Zealand(Massey University, 2013) Singh, YashpalWhole grain feeding has recently received renewed interest in the commercial poultry industry as a mean of lowering feed manufacturing cost. Wheat is the cereal grain of choice for whole grain feeding, despite the fact that globally maize is the most commonly cereal grain. Published data on the use of whole maize in poultry diets are scant. The size of maize grain may be the major reason for the lack of interest in feeding whole maize. The first three experiments of the thesis investigated alternative feeding strategies such as pre-pelleting inclusion or minor modifications such as cracking or coarser grinding to overcome the issue of maize kernel size. Experiment four evaluated whole wheat (WW) feding and examined the interaction between pellet diameter (3.0 vs 4.76 mm) and method of wheat inclusion (ground wheat (GW) or WW pre-and post-pelleting). The intention of using a larger pellet die was to retain the larger wheat particle size in pellets. Experiment five investigated the effect of whole wheat feeding in broilers experimentally challenged with a mixed infection of Eimeria. Pre-pelleting inclusion of 0 to 600 g/kg whole maize replacing (w/w) ground maize in broiler starter diets showed that the weight gain of broilers was poorer despite improvements in gizzard development, nutrient utilisation and pellet quality (Chapter 4). Poor weight gain was due largely to reduced feed intake. Inclusion of 0 to 600 g/kg coarse maize, replacing (w/w) finely-ground maize, in broiler diets in mash form from day 11 to 35 post-hatch resulted in improvements in weight gain and gizzard weight without any negative effect on nutrient utilisation and carcass yield (Chapter 5). Increased caecal counts of beneficial bacteria Lactobacilli spp. and Bifidobacteria spp. and decreased counts of Clostridium spp., Campylobacterium spp. and Bacteroides spp. were also reported. Similarly, feeding diets containing 0 to 600 g/kg coarse maize to laying hens, from 39 to 62weeks of age, had no adverse effects on any production parameters and egg quality (Chapter 6). These results indicated that ground maize in broiler and layer diets could be completely replaced by coarsely ground maize with no adverse effects of bird performance. . Data reported in Chapter 7 showed that the effect of pellet diameter on broiler performance varied depending on the form of wheat and method of WW inclusion. Larger pellet diameter increased the weight gain and lowered feed per gain of birds fed diets with GW and post-pellet inclusion of WW. However, in birds fed diets with pre-pelleting inclusion of WW, the larger pellet diameter lowered weight gain and increased feed per gain, due largely to reduced feed intake which may be attributed partly to poorer pellet quality. Relative gizzard weight was increased by larger pellet diameter with pre-pelleting inclusion of WW, but was unaffected by diets containing GW or post pelleting inclusion of WW. Larger pellet diameter increased the apparent metabolisable energy and ileal starch digestibility, irrespective of method of WW inclusion. These results suggested that, irrespective of whether the wheat grain was milled or added whole post-pelleting, a larger diameter pellet was beneficial. On the other hand, when WW was added pre-pelleting, a smaller diameter pellet resulted in improved weight and feed per gain in broiler performance. In the final experiment (Chapter 8), broilers fed WW either pre-or post-pelleting and experimentally challenged with a mixed Eimeria infection at 21 day of age showed that mortality in challenged birds was highest in those fed diets with WW post-pelleting, followed by pre-pelleted WW and GW (58, 35, and 17%, respectively). The pattern of mortality paralleled the changes in gizzard size, which suggested that WW feeding exacerbated the severity of coccidiosis infection, possibly via a mechanism involving enhanced gizzard development.Item Lipid biosynthesis in isolated chloroplasts : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biochemistry at Massey University(Massey University, 1979) McKee, Joseph William AdairTwo notable features of previous work on lipid biosynthesis by isolated chloroplasts have been:- (a) The inability of chloroplasts to incorporate more than small amounts of acetate into the main constituent fatty acids of the chloroplast lipids, namely linoleic (18:2) and linolenic (18:3) acids. (b) The poor incorporation of fatty acids synthesized into galactolipids, which are the main chloroplast lipids. Both of these aspects of lipid biosynthesis were investigated using chloroplasts isolated from spinach, maize and sweetcorn. Initial attempts to improve the synthesis of polyunsaturated fatty acids from [1-14C]acetate were not successful. Consequently the main object of the investigation was directed towards increasing the incorporation of long chain fatty acids into galactolipids in the hope that increased galactolipid synthesis might also lead to increased desaturation of oleate to linoleate and linolenate. Factors affecting the rates of acetate incorporation into lipids by spinach, maize and sweetcorn chloroplasts were investigated. Optimum concentrations of acetate, ATP and CoA were found to be about 0.5mM-acetate (spinach somewhat higher at 0.75mM-acetate), 0.5mM-ATP and 0.25mM-CoA under the incubation conditions used in the present study. Acetate concentration had a major effect on the rate of incorporation; optimisation of ATP and CoA concentrations gave only small enhancements of acetate incorporation. The effect of divalent cations was also investigated for spinach chloroplasts. Optimum Mg++ was 3.0mM; addition of 1mM-Mn++ in the presence of 1mM-Mg++ gave a comparable stimulation of acetate incorporation. Acetate incorporation by spinach chloroplasts was also enhanced by the addition of Triton X-100, sn-glycerol-3-phosphate and UDP-galactose. Maximum incorporation rates obtained for maize and sweetcorn chloroplasts were 20-30nmol of acetate/mg chlorophyll/h which are up to 10-fold higher than previously reported rates for maize. Rates of up to 500nmol of acetate/mg chlorophyll/h were obtained for spinach chloroplasts which compare favourably with the rates obtained by other workers using chloroplasts isolated from younger leaf tissue. Oleic and palmitic acids with small amounts of stearic acid were the main fatty acids synthesized from acetate by isolated chloroplasts from all three sources. Little synthesis of linoleic and linolenic acids was achieved and changes in acetate, ATP and CoA concentrations had no significant effect on the synthesis of polyunsaturated fatty acids from acetate. Triton X-100 and divalent metal ion concentrations also had little effect on the synthesis of polyunsaturated fatty acids by spinach chloroplasts. The synthesis of diglycerides (DG) by isolated chloroplasts from spinach, maize and sweetcorn was enhanced by the adaition of sn-glycerol-3-phosphate (G-3-P). Synthesis of monogalactosyldiglyceride (MGDG) was enhanced by the addition of UDP-galactose particularly if G-3-P was also present. Triton X-100 greatly enhanced the synthesis of DG and also (in the presence of UDP-galactose) MGDG by spinach chloroplasts. Spinach chloroplasts gave higher rates of DG and KGDG synthesis than either maize or sweetcorn chloroplasts. The synthesis of MGDG from DG by spinach chloroplasts was investigated by double-labelling experiments, using [1(3)-3H]sn-glycerol-3-phosphate and [1-14C]acetate, fatty acid analysis and positional distribution of the incorporated fatty acids. The synthesis of MGDG was shown to occur without prior modification of the fatty acid composition of the DG. It was evident from the incorporation of oleate and palmitate into DG (and subsequently into MGDG) and from the positional distribution of these two fatty acids that a specific acylation of G-3-P occured synthesizing mainly 1-oleoyl, 2-palmitoyl-sn-glycerol. The effects of altering the proportions of oleate and palmitate synthesized on the relative amounts of these fatty acids incorporated into DG (and MGDG) were investigated. The results suggested that palmitate was incorporated into position 2 first followed by oleate into position 1. If there was more palmitate than oleate synthesized some palmitate could be also incorporated into position 1. The rates of DG synthesis calculated from [1 (3)-3H]-sn-glycerol-3-phosphate incorporation were conniderably greater than those calculated from [1-14c]acetate incorporation indicating that a considerable dilution of the label from [1-14c]acetate had occurred and that a major proportion of the fatty acid carbon had come from an alternative source. Bicarbonate, present in the reaction medium, was found to be utilized by spinach chloroplasts for the synthesis of fatty acids and lipids. Thus bicarbonate was probably the alternative source of fatty acid carbon. The fatty acids and lipids synthesized by spinach chloroplasts from exogenous acetate and bicarbonate were very similar. Although high rates of DG and MGDG synthesis have been achieved in the course of the present study by the addition of appropriate metabolites, stimulation of synthesis of these lipids did not alter the rates of synthesis of linoleic and linolenic acids from acetate. Other attempts to increase polyunsaturated fatty acid synthesis from acetate by isolated chloroplasts were also unsuccessful. The use of chloroplasts isolated from developing maize leaf sections had little effect on the rates of linoleic and linolenic acids synthesized from acetate. The addition of a 100,000 X g particulate preparation from leaf homogenate to isolated maize and spinach chloroplasts though stimulating overall incorporation of acetate, gave only minor increases in the proportion of linoleic and linolenic acids synthesized. The stimulation of phosphatidylcholine synthesis by the particulate fraction, in the presence of isolated chloroplasts, failed to result in any dramatic increases in the proportions of polyunsaturated fatty acids syntheisized. These findings are discussed in relation to the current understanding of fatty acid and lipid synthesis and recent in vivo and in vitro studies of plant lipid synthesis.Item Physical changes in maize (Zea mays L.) grains during postharvest drying : a thesis presented in partial fulfillment of the requirements for degree of Doctor of Philosophy in Seed Technology at Massey University(Massey University, 2000) Kim, Tae HoonStress cracking due to high temperature drying has been of concern to the maize industry because it can lead to increases in broken grain and fine material during subsequent handling. In this study, several factors affecting physical characteristics of maize grain, particularly those related to stress cracking, were investigated. In the first year (1995-1996), the effects of several preharvest factors; hybrid, nitrogen, harvest grain moisture content, and postharvest drying factors including drying temperature and relative cooling rate on physical attributes and stress cracking in grain were investigated. Grain hardness (hard to soft endosperm ratio (H/S ratio)) was significantly affected by the interaction between hybrid and nitrogen. The effect of drying temperature and harvest moisture on drying time was dominant, while drying rate was significantly affected by hybrid and drying temperature. The effect of cooling rate on stress cracking and stress crack index (SCI) stood out among the main effects. At the lowest cooling rate of 0.23 (°C/°C/min.)•10-2, checked stress cracking (checking) was minimal, and SCI was less than 100. However, at higher cooling rates from 0.55 to 1.11 (°C/°C/min.)•10-2, grains had more than 25% multiple stress cracking, regardless of the levels of hybrid, nitrogen, harvest moisture and drying temperature. The predicted SCI for the three hybrids reached a maximum around at 0.75 (°C/°C/min.)•10-2, cooling rate, irrespective of levels of nitrogen and drying temperature. In the second experiment (1996-1997), the effects of grain hardness and morphological factors (grain size and shape) at a single grain drying rate and the development stress cracking over time were investigated. The re-parameterized Morgan-Mercer-Flodin (MMF) model successfully predicted the increasing rate (κ) and the maximum value (α) of percentage checking in various sizes, shapes and hardness of grains time after drying. From the data analysis, the maximum value of checking (α) showed a significant correlation with grain length (r = -0.707), thickness (r = 0.620), roundness (r = 0.703) and the shortest diffusion pathway (SDP; r = 0.627). While, the increasing rate (κ) of percentage checking with time after drying was significantly correlated with grain bulk density (r = -0.564), hardness ratio (r = -0.611) and drying rate (r = 0.551), and to a lesser extent (r > 0.35), with the grain size parameters including hundred-grain weight, grain length, and width. Based on this result, it was suggested that removing small and rounded grains could reduce checked stress cracking by up to 40 to 50% in some dent maize hybrids. In addition, the standardized multiple regression for single grain drying rate according to H/S ratio and grain weight accounted for from 65 to 74% of the variation. Tempering grain at high temperatures reduced stress-cracked grains significantly. However, the effect of tempering on stress cracking in the hard grain hybrid was small. In the 1997-1998 experiment, a breakage tester (HT-I drop tester) was developed and single grain breakage at various grain temperatures and times after drying was determined. Both hard and soft maize hybrids had minimal breakage at high grain temperatures (78 to 110°C), while decreasing grain temperature increased breakage exponentially. This indicated that grain temperature should be considered as a co-factor for measuring grain breakage. After drying at both 60°C and 120°C, the percentage breakage measured at ambient temperature increased rapidly during cooling in air at an ambient temperature of 20°C and a relative humidity around 65-70%. Breakage reached a maximum after about 10 minutes from the start of cooling. A Mitscherlich function was used to describe the chronological development of percent grain breakage and the analysis of the function parameters for the extent (maximum) and rate of breakage indicated that there was a significant interaction between hybrid and drying temperature for the development of grain breakage after drying. In conclusion, the MMF and Mitscherlich models described stress cracking and grain breakage during drying and cooling of maize grain. These studies provide valuable information to grain industries to assist with minimizing grain damage during drying.