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    The effect of defoliation frequency and height on plantain and chicory-based swards
    (2021) Cranston L; Kenyon P; Morris S; Lopez-Villalobos N; Kemp P
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    The mineral content of some tropical forages commonly used in small ruminant production systems in the Caribbean - Part 2
    (University of West Indies Press, 2021-01) Cranston L
    Understanding the differences in the mineral concentrations of forages is critical as it informs on which and how species can be used to improve the mineral content of diets. Also, with the constantly changing nutritive value of forages, regulating the mineral composition through on-going forage evaluation is important as deficient minerals can be identified and supplemented. Therefore, the aim of this study was to provide information on the mineral profiles for 12 forage species used in small ruminant production systems in the Caribbean. The forage species included seven grasses (Brachiaria arrecta, Brachiaria ruziziensis x), Cynodon dactylon, Cynodon, nlemfuensis, Digitaria eriantha, Megathyrsus maximus and Pennisetum purpureum); two leguminous multipurpose tree species (LMPTs) (Gliricidia sepium and Leucaena leucocephala) and three non-leguminous multipurpose tree species (NLMPTs) (Moringa oleifera, Morus alba and Trichanthera gigantea). Overall, the calcium, phosphorus, magnesium, cobalt, manganese, and zinc were within the range required for small ruminants. Brachiaria arrecta and Digitaria eriantha were the only two species with Na concentrations that were within the range required for small ruminants (0.9626 and 4.4281 g/kg DM respectively). Brachiaria arrecta, Cynodon dactylon, Cynodon nlemfuensis, Leucaena leucocephala and Trichanthera gigantea were the only species with copper concentrations that were within the range required for small ruminants (11.50, 20.24, 11.95, 8.16 and 16.60 mg/kg DM). The concentration of potassium in Pennisetum purpureum (39.1 g/kg DM), Brachiaria arrecta (32.6 g/kg DM), and Cynodon nlemfuensis (34.0 g/kg DM), the concentration of iron in Cynodon dactylon (3340 g/kg DM) and molybdenum in both Cynodon dactylon (8.615 mg/kg DM) and Cynodon nlemfuensis (7.722 mg/kg DM) were above the maximum tolerable levels for small ruminants. The results of the study suggest that forages varied in mineral concentrations and the toxic and marginal concentrations of specific minerals in various forage species elicit the careful management of inclusion in diets, to ensure that the mineral concentrations are within the range required for small ruminants.
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    Determining the chemical composition and in vitro digestibility of forage species used in small ruminant production systems in the english speaking Caribbean - Part 1
    (University of West Indies Press, 2021-01) Cranston L
    The nutritional evaluation of tropical forages in the Caribbean is limited. Therefore, this study was done to provide information on the nutritive value of 12 forages used in regional small ruminant production systems in the Caribbean region, utilising three different methods of forage evaluation. Samples of seven grasses Brachiaria arrecta, Brachiaria ruziziensis, Cynodon dactylon, Cynodon nlemfuensis, Digitaria eriantha, Megathyrsus maximus and Pennisetum purpureum; two leguminous multipurpose tree species (LMPTs) Gliricidia sepium and Leucaena leucocephala and three non-leguminous multipurpose tree species (NLMPTs) Moringa oleifera, Morus alba and Trichanthera gigantea were collected from one of two sites located in Trinidad and Jamaica. Analysis of nutritive value was done using proximate analysis, in vitro assays and near infrared spectroscopy (NIRS). Cynodon nlemfuensis had the highest crude protein (CP, 191.2 g/kg DM) of the grasses and Leucaena leucocephala and Moringa oleifera the highest CP (263.6 and 232.5 g/kg DM respectively) of the LMPTs and NLMPTs. The NLMPTs, Moringa oleifera and Morus alba had the highest starch, highest in vitro digestible organic matter in dry matter (IVDOMD, 651 and 655 g/kg DM respectively) and metabolisable energy (ME, 10.62 and 10.68 MJ/kg DM respectively) and the lowest neutral detergent fibre (NDF) of the MPTs. There was a strong positive relationship between the IVDOMD and both the CP and starch fractions and a strong negative relationship between the IVDOMD and both the NDF and acid detergent fibre (ADF) fractions. The NIRS predicted values had a strong relationship with the gross chemical CP, NDF, IVDOMD and ME) values of tropical forage species (R2 = 0.91, 0.86, 0.70 and 0.80 respectively). Overall, the forage species were above the minimum CP, IVDOMD and ME required to be classified as intermediate to good quality forages.
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    The growth response of Pasture Brome (Bromus valdivianus Phil.) to defoliation frequency under two soil water restriction levels
    (MDPI AG, 15/02/2021) Cranston L
    Pasture brome (Bromus valdivianus Phil.) has the potential to increase current levels of herbage production and pasture persistence in New Zealand dryland, well-drained soils. However, there is little literature on the effect of defoliation management on growth of this grass under contrasting soil-water restriction levels. The growth physiology and performance of pasture brome were evaluated in pots in a glasshouse. Defoliation frequency (DF) treatments were applied based on three different accumulated growing degree-days (AGDD): 250, 500 and 1000 AGDD (high, medium, and low DF). At end of the first growing cycle (1000 AGDD), water availability was restricted to 20–25% of field capacity (FC) in half of the pots, while the other pots were maintained between 80–85% FC. Total accumulated herbage mass was positively related with the low DF and well-watered conditions (p < 0.05). At the final harvest, plants subjected to low DF had greater root mass than high and medium DF (p < 0.05). At each harvest, the leaf regrowth stage (LS) for low DF was 3.5, while for high and medium DF, the LS was 1.5 and 2.0; respectively. Tiller water-soluble carbohydrates were highest at the low DF and under 20–25% FC. Regardless of soil-water conditions, defoliation at 3.5 LS supports production, enhancing survival during a drought.