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    Influence of feed processing and enzyme supplementation on performance, nutrient utilisation and gut morphology of poultry fed barley-based diets : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Poultry Nutrition at Massey University, Palmerston North, Manawatu, New Zealand
    (Massey University, 2020) Perera, Wellawattage Nipuna Udayani
    The first experiment (Chapter 3) determined the metabolisable energy and standardised ileal digestible amino acids of two barley cultivars (NSH [normal starch hulled barley] and WSHL [waxy starch hull-less barley]) and wheat for broilers. These values were used to formulate the experimental diets in subsequent experiments that evaluated the optimum barley inclusion rate in wheat-based diets (Chapters 4 and 5), optimum barley particle size (Chapter 6) and conditioning temperature (CT; Chapter 7), and potential interaction of carbohydrases with each processing parameter. In Chapter 3, wheat and WSHL had the highest and lowest metabolisable energy and digestible amino acid contents, respectively, with NSH being intermediate. Supplemental carbohydrases increased the energy utilisation with a pronounced effect in WSHL. Data reported in Chapter 4 showed that optimum inclusion level of NSH was 283 g/kg of diet. Nutrient utilisation linearly improved with increasing inclusions of NSH. Carbohydrases improved feed per gain (F/G) and nutrient utilisation. Chapter 5 suggested that WSHL could be safely included up to 260 g/kg in a wheat-based diet with no adverse effect on growth performance. Carbohydrases improved the F/G and, starch and energy utilisation. In Chapter 6, particle size effect was preserved after pelleting and, coarse barley and carbohydrases improved the F/G and nutrient utilisation. The combination of carbohydrase and phytase produced no further improvements in nutrient utilisation. The final experiment (Chapter 7) demonstrated that better pellet quality achieved by increasing CT to 88 °C failed to ameliorate the negative impacts of high CT on nutrient utilisation and broiler performance. Carbohydrases improved weight gain, F/G and, starch and energy utilisation. The lack of interaction between the carbohydrases and CT indicated that carbohydrase had similar efficacy at each CT. The primary finding of this thesis research was that if cultivar-specific values for metabolisable energy and digestible amino acids are used in feed formulations, barley has the potential to substitute up to 50% of wheat in broiler diets. Coarse particle size (8.0 mm) and conditioning the diets up to 74 °C is recommended for the tested barley type. Supplemental carbohydrases improved the feeding value of barley for broilers.
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    Effect of differences in live weight on feed requirements of pregnant non-lactating grazing dairy cows : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University, Palmerston North, New Zealand
    (Massey University, 1994) Garćia-Muñiz, J G
    The effect of differences in live weight (LW) on feed requirements of pregnant non-lactating cows was assessed during a 41-day grazing experiment. Thirty eight dry pregnant Friesian and Jersey cows (28 Friesian cows differing in live weight and 10 Jerseys) at similar stages of pregnancy (range 190 to 230 days pregnant) and averaging 5.8 years of age were used. The cows were grouped according to their initial LW in three size-groups, i.e. Big Friesians (BF; n=14, LW = 526 kg), Small Friesians (SF; n=14, LW = 415 kg) and Jerseys (J; n=10, LW = 362 kg). Within each size-group the cows were randomly allocated to one of two levels of daily herbage dry matter (DM) allowance (HA), calculated to meet either maintenance and pregnancy (i.e. HA of 7.7 to 11.0 kg DM/cow/day), or the gain of 1 kg of maternal live weight above maintenance and pregnancy (i.e. HA of 17.1 to 22.5 kg DM/cow/day). The cows provided individual records of their daily liveweight gain (LWG, kg/cow), total liveweight gain (ΔLW) and total condition score change (ΔCS) achieved during the 41-day experimental period. Group average herbage dry matter intake (DMI) and herbage DM allowance were calculated for each treatment group from herbage mass (HM) assessed by cutting-washing-drying and weighing, and by means of two calibration equations, one for each level of feeding, relating HM to the average of 30 plate meter readings (PMR) taken every day before and after grazing. These two calibration equations were: (1) for the ad libitum level of feeding: HM (kg DM/ha) = 764.0 (s.e. 212.0) + 158.0 (s.e. 12.7) * PMR (r = 0.98; CV = 24%; r.s.d. = 548 kg DM), and (2) for the maintenance fed cows: HM (kg DM/ha) = 171.0 (s.e, 3.5) * PMR (r = 0.98; CV = 21.6%; r.s.d. = 442 kg DM). The energy content of the herbage (MJ ME/kg DM) apparently grazed by the cows and their metabolizable energy intake (MEI) were calculated from the in vitro digestibility analyses of pasture samples plucked randomly from each of the grazing areas. Least squares means were calculated for group average herbage dry matter intake (DMI), herbage DM allowance (HA), metabolizable energy intake (MEI), and for the variables derived from the animals' performance (ΔLW, LWG, ΔCS) and differences between levels of feeding and size-groups were tested for significance using analysis of variance. Differences in average live weight between the three size-groups were highly significant (P<0.001) throughout the experimental period (i.e. BF = 552 kg; SF = 442 kg; J = 377 kg). Heavier cows had: (1) significantly higher daily herbage DM allowances (BF, 16.7; SF, 14.4; J, 12.4 kg/cow/day); (2) higher daily DMI (BF, 10.2; SF, 8.6; J, 7.5 kg/cow/day); (3) higher MEI (BF, 117; SF, 100; J, 87 MJ/cow/day), and (4) lower stocking densities (BF, 240; SF, 262; J, 305 cows/ha/24 hours). However, when HA, DMI and MEI where expressed on a metabolic weight basis, none of these variables were significantly different between the three size-groups. From the least squares means of LWG, ΔCS, DMI and MEI calculated for each treatment group, feed requirements for zero ΔCS or maintenance (i.e. MEm) and feed requirements for ΔCS were calculated by means of linear regression analyses. The MEm calculated pooling the three size-groups was 0.648 MJ ME/LW0.75/day for zero ΔCS; and an average intake of 167 kg DM or 1986 MJ ME/cow above maintenance was required for the gain of one condition score unit/cow during the 41 days of experimental period, which was equivalent to a total liveweight change of 52.7 kg/cow. From these estimates it was calculated that cows heavier by 100 kg required an extra intake for maintenance of 10.5 MJ ME/cow/day or about 0.95 kg herbage dry matter intake/cow/day. The results of the present experiment were used to assess the effect of farming large-size cattle on the productive efficiency of pasture-based dairy systems.