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    A study of the effect of the digestibility of hay on its feeding value when given to lactating cows grazing on pasture : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science, Department of Animal Science, Massey University
    (Massey University, 1990) Sangsritavong, Sunan
    Sixteen cows with an average milk yield of 20 litres per day, were randomly allocated to two treatment groups. One group was supplemented with high digestibility hay (57 .3% DMD) while the other group was supplemented with low digestibility hay (52.0% DMD). Cows in both treatments grazed on pasture during the night time and were stall-fed with either high or low digestibility hay during the day time. The pastures were predominantly of perennial ryegrass (Lolium perene). The experiment was carried out for 28 days in September 1988. The two treatment groups were given a common pasture allowance of 11-12 kgDM per cow per 12 hour period of grazing. Hay intake (fed ad libitum), pasture intake, milk yield, milk composition, liveweight and condition score were measured. Herbage intake was estimated by the sward cutting technique and was 3.85 and 4.30 kgDM per cow per day for the high and low digestibility hay groups respectively. The difference between the groups in intake was significant (P<0.05). Daily intake of high digestibility hay (8.65 kgDM per cow) was significantly (P<0.0001) greater than the consumption of low digestibility hay (6.53 kgDM per cow). The estimated values for daily metabolisable energy intake were 115 MJ per cow and 99 MJ per cow for the high digestibility and low digestibility hay groups respectively. Residual herbage mass was slightly higher (1130 v 1100 kgDM per hectare), but not significantly, when cows were supplemented by high digestibility hay. Substitution rate for the increase in hay intake was -0.45 kgDM pasture intake for an increase of 2.12 kgDM of hay intake or 0.21 kgDM pasture per one kgDM increase in hay intake. Cows fed on the high digestibility hay produced slightly more milk than those on the low digestibility hay. The difference was significant (P<0.01) in week 1 but not significant thereafter. Yields of milk constituents were also slightly increased for cows fed on the high digestibility hay. Digestibility of hay had small and insignificant effects on the concentrations of milk fat, milk protein and milk lactose. However the concentration of milk fat and milk protein were slightly higher for cows fed low digestibility hay. Cows fed high digestibility hay gained significantly more liveweight (P<0.05) and condition score (P
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    The development and significance of fungi in poultry rearing sheds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University
    (Massey University, 1984) Mylvaganam, Indira A
    A study was conducted at the Poultry Research Centre, Massey University, to determine the numbers, types and patterns of development of fungi that occur in poultry rearing sheds. Two sheds, a broiler shed and a layer shed were analysed for the fungal population by weekly sampling of litter, feed and air. Particular emphasis was placed on the presence of Penicillium and Aspergillus as these genera contain species of potential significance to flock health as infectious or toxigenic agents. Use of the dilution plating method with modified Potato Dextrose Agar and Aspergillus Differential Medium for culture resulted in successful isolation of these genera. Further selectivity was attained with the use of a modification of the strip-bait method of Luttrell (1967}. Air sampling was by the exposed agar plate method. The poultry houses were found to contain high levels of viable fungal propagules. Of the total fungi, Penicillium, Aspergillus and Scopulariopsis were the major genera. Other genera included Rhizopus, Mucor, Cladosporium and Geotrichum. Penicillium was found throughout the trials. Scopulariopsis was present at low levels in fresh litter and feed but counts increased greatly with time. Counts of species of Aspergillus, (A. flavus and A. fumigatus) also showed increases mainly towards the end of the trials. Other genera (Geotrichum, Cladosporium etc.) were found on certain days only. As litter aged, its pH and moisture content increased and these increases were correlated to the increase in total fungal numbers during the period of housing. Patterns of fungal succession in the litter were similar to those in air. For some species the increases in numbers in litter were preceded by a similar peak in the air (eg. A. flavus) whereas for others the peak in litter was earlier than the peak in air (S. brevicaulis). The correlation between patterns in air and those in feed and litter was more obvious in the layer shed, where a more active flock created greater air movement than in the broiler shed where the birds were docile and caused very little circulation of air. A. flavus isolates were screened for the production of aflatoxin on coconut agar. Approximately 30% of all A. flavus isolates tested were toxigenic. Also, it was possible to extract the toxin after growth in semisynthetic liquid medium from isolates which had been strongly fluorescent on coconut agar, but not those which had been weakly fluorescent. Feed and litter samples tested for the presence of aflatoxin and other mycotoxins (T-2, ochratoxin and zearalenone) were negative for these mycotoxins. The fungal population of poultry houses has been shown to include species which may be of economic importance. The large amounts of A. flavus (potentially toxigenic) and A. fumigatus (infectious), in particular, should not be ignored as they may well affect poultry health and productivity.