Massey Documents by Type
Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294
Browse
35 results
Search Results
Item A dynamical systems model for optimizing rotational grazing : a thesis presented in partial fulfilment of the requirements for the degree of Ph. D. in Mathematics at Massey University(Massey University, 1993) Woodward, SimonThis thesis considers modelling agricultural grazing using dynamical systems. It is in five chapters, some of which have been or will be published in international refereed journals. The first chapter considers grazing a two-paddock system at low pasture mass in order to maximise herbage conservation and/or herbage intake. For the latter objective, there is an optimal swap-over time which depends on the initial herbage masses and the stocking densities. In general, optimal swap-over gives only small improvements in herbage intake compared to continuous grazing or rotational grazing in which animals spend equal time in each paddock. The second chapter applies this to comparing continuous, rotational, and optimal grazing strategies over a range of stocking rates. As stocking rate increases optimal rotational grazing can increase herbage intake. The third chapter deals with grazing a multi-paddock system in order to maximise intake. Animals are shifted at regular time intervals. Stocking rate and average initial herbage have the greatest effect on herbage growth, conservation, and intake. Grazing strategy effects are less significant. However, traditional strategies of rotational grazing perform poorly in some cases, and in these cases a "greedy" grazing strategy can give imporoved production. The difficulties of finding optimal strategies are discussed. The fourth chapter examines modelling senescence in grazed grass pasture using a differential-delay equation where senescence rates are explicitly dependent on leaf age. A simple differential-delay model is formulated and appraised by comparison to data from a published grazing experiment. This simple model describes subtle features of pasture dynamics. The fifth chapter uses this delay model to make a simple comparison between rotational and continuous grazing. The average rate of senescence is higher under rotational grazing and this is exacerbated by delay effects. For this reason, production is likely to be lower under rotational grazing.Item Pasture utilization in relation to New Zealand dairy farming : a thesis presented in part fulfilment of the requirements for the Animal Husbandry section of the degree of Master of Agricultural Science at Massey University, New Zealand(Massey University, 1949) McArthur, Alistair Thomas GilesThe world shortage of food is the most serious crisis which faces mankind today. It is a crisis which has no earlier precedent and one for which remedial measures will be hard to find. The problem, first mentioned by Malthus in 1798, is one of limited food resources combined with an increasing world population. The basis of food production lies in the soil mantle of the world which is limited in extent and decreases yearly both in quantity and quality through the use of bad farming practices which lead to soil erosin. The present level of human nutrition throughout the world is far from adequate. In North .America and Australasia, the average daily consumption of calories per head is above 3000 but in the Middle East it is only 2400 while in the Far East it varies between 1700 and 2100, which is well below requirements (Fawcett (1948)). Not only are these people in need of more food energy but they also require more protein, minerals and vitamins. Livestock products are, of course, rich in these 'protective' foods and the expansion of livestock production will play an important part in raising the level of nutrition of the world's population. [From Introduction]Item Targeted duration controlled grazing - the effects of timing of grazing on nitrate leaching and treading damage : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand(Massey University, 2019) Howes, JayDuration controlled (DC) grazing is successfully employed for two main reasons: to reduce N leaching and to protect pastures and soils from treading damage in wet conditions. These two objectives are currently very important for the New Zealand (NZ) dairy industry and this will only continue to increase with changing environmental expectations and legislation. However, while there have been a number of studies showing the benefits of DC grazing, there has not been any detailed research into the means to modify or improve the management of DC grazing systems. Therefore, the overall objectives of this research were to further the understanding of the advantages of targeted cow standoff from pastures during the late-summer to early-winter period and its effect on nitrate (NO3-) leaching, and to identify the relationship between soil water deficit (SWD), grazing duration and treading damage (related to standoff in winter to early spring). Two experiments were conducted on a fine textured Tokomaru silt loam soil at Massey University’s Dairy 4 Farm near Palmerston North, Manawatu, New Zealand. One experiment was conducted to investigate the interaction of grazing duration and SWD on soil damage and pasture production, while the other experiment compared NO3- leaching under a standard dairy grazing system and a grazing system that used targeted DC grazing (i.e. during late-summer to early-winter). Irrespective of drainage season and grazing treatment, the greatest NO3- concentrations in drainage occurred in the first seven to eight drainage events, which equated to the initial 50 to 100 mm of drainage. The majority of N losses following this were in the form of total organic nitrogen (TON). The average reductions in NO3- and TN leaching following targeted DC grazing in the summer to early winter periods of 2015 and 2016 were 28% and 20% respectively. The uniform return of slurry contributed to the DC treatment maintaining similar pasture production to the standard grazing treatment. Compared with year-round DC grazing, targeted DC grazing could be relatively inexpensive and so is likely to be a good mitigation option for N leaching in many cases, particularly on free draining soils where treading damage is uncommon. Treading damage can be easy to observe; however, it can be time consuming to measure and even more difficult to quantify in a spatially aware manner. Therefore, two new and contrasting methods of assessing treading damage were developed, namely, the visual scoring method and the pugometer. The advantage of the pugometer is that it can automatically capture spatial variability rapidly, which no current method is able to do. Only minimal treading damage and no reduction in pasture production was associated with cows grazing pasture at SWD > 2 mm, and this SWD appears to be a critical value, which farmers on fine textured soils, like the Tokomaru silt loam, could use to schedule grazing to protect soils and pastures from pugging damage. However, due to the need to maintain pasture quality there will be numerous occasions when the pasture on farms practising DC grazing will need to be grazed at a SWD < 2 mm. A modelling exercise revealed that up to 60% of a farm with standoff facilities could be damaged in an average season. While the damage inflicted on pastures may look unsightly, this may have little influence on overall accumulated (annual) pasture production. However, when the SWD was less than 2 mm, there were short-term losses in pasture production of approximately 500 to 1000 kg DM/ha under the grazing regimes studied here (i.e. 4- or 8-hour grazing duration and single and repeat damage events). If there is a need to graze in wet conditions (at or near saturation), then short durations (up to 4 hours) are recommended. Targeted DC grazing management provides the opportunity to achieve improved environmental outcomes, and the effectiveness of targeted DC grazing as a multi-purpose tool is not undermined by the need to graze in wet conditions.Item Behavior changes in grazing dairy cows during the transition period are associated with risk of disease : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatū, New Zealand(Massey University, 2020) Hendriks, StaceyThere is growing interest in the use of behavior data derived from accelerometers as a potential measure of animal health, however, research determining the optimal use of these devices and the interpretation of data derived from them, is lacking, particularly in grazing systems. The aims of this thesis were to understand: 1) data management considerations that need to be taken into account when using accelerometer devices to measure behavior in a research setting; 2) environmental and other potentially-confounding variables that can influence cow behavior and, therefore, the interpretation of behavior data; 3) ‘normal’ behavior of clinically-healthy grazing dairy cows during the transition period, and; 4) changes to behavior of grazing dairy cows experiencing varying degrees of hypocalcemia and hyperketonemia. To do this, data from 4 separate parent experiments were collated to generate a database containing detailed phenotype data, including, but not limited to, measures of cow performance (e.g., milk production and composition, body weight and body condition score), cow health (e.g., energy and protein metabolites, minerals, liver enzymes, and immune markers in blood), and cow behavior (e.g., lying behavior and activity derived from triaxial accelerometers). My review of the appropriate use of leg-mounted accelerometers to monitor lying behaviors of dairy cows indicated that applying editing criteria to remove errors in lying behavior data caused by erroneous movements of the leg (e.g., scratching and kicking) can improve the accuracy of data derived from accelerometers for recording daily lying bouts (LB); however, has little to no impact on the accuracy of lying time. Lying behavior data must be edited using a suitable LB criterion where the interest is in studying both lying time and LB. My results indicated that inclement weather, parity, and physiological state are important variables that influence behavior in their own right and must be considered in subsequent analyses. Interestingly, when comparing my results with lying behaviors previously reported in housed cows, my results indicated that grazing dairy cows engage in similar lying behaviors to housed cows before and at the time of calving, while postcalving, grazing cows spend less time lying. Furthermore, grazing dairy cows displayed greater behavioral synchrony (i.e., cows engaged in the same behaviors simultaneously) compared with reports in housed cows. These postcalving differences highlight the importance of assessing behavior within the farming system of interest. My results also indicated that cows alter their behavior in response to ill health, whereby grazing dairy cows experiencing clinical hypocalcemia (without paresis) and hyperketonemia [with severe negative energy balance (NEB)] altered their behavior before, at the time of, and after disease diagnosis compared with healthy cows. My results indicated that behavioral differences between cows classified into 3 blood calcium groups [clinically-hypocalcemic (without paresis), subclinically-hypocalcemic, and normocalcemic] were transient. On the day of calving, clinically-hypocalcemic cows (without paresis), were less active, spent more time lying, and had more frequent LB compared with subclinically-hypocalcemic and normocalcemic cows; however, changes in behavior were short lived and were no longer present by 2 d postcalving. My results indicate that observed differences in behavior associated with hypocalcemia are small and may not be biologically significant as a metric to discriminate between hypocalcemic and normocalcemic cows. On the contrary, changes in behavior over time and within cow may allow differences between hypocalcemic and normocalcemic cows to be more easily discerned than using mean values of lying behavior and activity at a specific time point. My findings indicated that a relative increase in the number of steps taken within cow compared with a baseline period 2 wk precalving was positively associated with blood calcium concentrations postcalving. Further, my results indicated the behavioral differences between cows classified into 3 energy status groups [Hi–Hi = high non-esterified fatty acids (NEFA) and high β-hydroxybutyrate (BHB); Hi–Lo = high NEFA and low BHB, and; Lo–Lo = low NEFA and low BHB] occurred up to 2 wk before calving. During the 2 wk before calving, cows identified as Hi–Hi were more active, spent less time lying, and had fewer LB than the other 2 energy status groups. Interestingly, similar to the hypocalcemia work, my results indicated that a relative increase in the number of steps taken within cow during the 2 wk before calving was associated with lower odds of developing hyperketonemia with NEB; therefore, greater increases in activity before calving were associated with improved health outcomes postcalving in both studies. My results suggest that relative changes in behavior, in particular, step activity, might be an improved metric to discriminate between clinically-healthy grazing cows and cows experiencing a subclinical metabolic disease. My research provides an improved understanding of the associations between cow behavior and health, particularly for grazing dairy cows. This information provides a base for further exploring the potential for behavior and activity measures to identify cows experiencing ill health during the transition period. Future work should focus on continuing to improve our understanding of associations between behavior and disease, particularly in grazing dairy cows. Using within-cow behavior measures and determining how these data could be interpreted so that farmers could be alerted to sick animals and make actionable decisions on farm, should be the focus of future studies.Item Dietary crude protein and nitrogen utilisation in two contrasting dairy systems : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, School of Agriculture and Environment, Massey University, Palmerston North, New Zealand(Massey University, 2020) Correa-Luna, MartinThis thesis evaluated the efficiency of crude protein utilisation (ECPU) in dairy cows and nitrogen (N) utilisation efficiency (NUE) of two pasture-based dairy systems differing in intensification levels in New Zealand. During two consecutive seasons, in the low-intensity production system (LIPS), 257 cows were milked once-daily with low supplementation, and in the high-intensity production system (HIPS), 210 cows were milked twice-daily with higher supplementation. At every herd test, ECPU was calculated as protein yield (PY) divided by crude protein intake (CPI), estimated from feed intake. Milk urea (MU) was measured in early-, mid-, and late-lactation. Urinary N was estimated by back-calculation from estimated faecal N, taking into consideration N contained in milk and in body tissues. Pasture allocation represented 93% and 65% of the total intake for LIPS and HIPS cows, respectively, resulting in higher CPI for LIPS cows throughout the lactation. Compared to HIPS cows, LIPS cows produced 22% and 16% less milk and protein, with 32% higher MU, and 25% lower ECPU. Urine N was 34% higher in LIPS cows but faecal N was 5% higher for HIPS cows. A multivariate predictive model of ECPU was developed, including milk production performance, live weight variation, diet composition and quality along with climatic variables. The model accurately predicted the ECPU in an internal validation dataset (RPE = 6.96%, R2 = 0.95). Milk urea was not selected as a predictive variable of ECPU, considering that cows of higher ECPU also had higher MU. Compared with cows of high MU genetic merit, cows of lower MU genetic merit had lower milk production and similar ECPU. A whole-farm assessment of NUE, N losses and financial analysis was undertaken. On whole-farm level, LIPS produced 23% less milk and NUE was 31% lower when compared to HIPS. The lower MY along with the 35% higher N fertiliser applied on LIPS produced a higher N surplus per ha causing higher N losses when compared to HIPS. Despite the higher feed costs of HIPS, profitability was 16% higher because of milking more cows with higher MY when compared to LIPS.Item Association among pasture-level variables and grazing dairy cow responses to supplementary feeds : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Manawatū, New Zealand(Massey University, 2018) Poole, Caitlyn MarieThe milk production response to additional feed (i.e., supplement) is dependent on the relative feed deficit (RFD) of the cow. We hypothesized that the relative feed deficit could be defined by post-grazing residual (PGR), with a greater PGR indicating less of a relative feed deficit. We undertook a computerized literature review, utilising key words associated with grazing systems and supplementary feed. Approximately 70 published manuscripts were reviewed. Only those that satisfied predetermined inclusion criteria were retained. A meta-analysis was undertaken across all the studies using random coefficient regression fitted as a mixed-model. In total, we collated data from 26 experiments and 90 treatments, wherein pasture-level variables, supplementary feed variables, and milk production were reported. Due to a lack of reporting of standard errors, two analyses were undertaken; one where responses were weighted against the reciprocal of the standard error of the mean, and one where they were not. On average, pasture DM intake declined (-0.28 kg/kg supplement DM; P = 0.001) and milk, fat, and protein increased (P < 0.001) 0.65 kg, 20g, and 30g/kg supplement DM, respectively. For every kg DM supplement consumed, PGR height and mass increased by 1.4 mm and 42 kg DM/ha. These results were similar in the non-weighted analysis. Associated with every 10 mm increase in PGR height in the control treatment, marginal milk response declined (P < 0.05) by 55 ± 21.6 g. The association between PGR height and pasture DMI at zero supplementary feed intake (i.e., unsupplemented group in experiment) on the PGR and pasture DMI responses to supplementary feed, were however, inconsistent in the weighted and non-weighted analysis. These results will enable farmers to use the change in PGR when feeding supplements, to estimate likely marginal milk production response to supplementary feeds. These results are associations only and need to be tested in controlled, interventionist, experiments. Due the number of variables affecting MR, we cannot conclude that anything is causative.Item The use of simulation in the study of grazing management problems : a thesis ... Master of Agricultural Science ... Massey University of Manawatu.(Massey University, 1963) Arcus, Peter LaurenceGrazing Management is a large and integral part of farm management in New Zealand. It involves the making and implementing of all the decisions relating to the grazing of animals. This is a complex management function which necessitates the assessment and integration of a large number of factors. Grazing Management involves decisions relating to all aspects of pasture production, its utilization by grazing animals, and the efficiency with which these animals convert the pasture ingested into useful livestock products. Many factors are involved. These include soil type, pasture composition, fertilizer, type, age and number of livestock, grazing method, and the influence of season. Many of these factors interact with each other. Pasture production for instance, is influenced by the number of stock present, and the grazing method. Equally, livestock intakes and productions depend on pasture availability and composition. These interactions are a major influence in grazing management. The timing of events is also important in grazing management. Many decisions depend for their effectiveness on being made and implemented at the "right" time. Fertilizer applied in the spring or autumn, for example, is of more value in stimulating pasture growth and if applied in the slower growing periods of summer or winter. [From Introduction]Item Some aspects of grazing ecosystems : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University(Massey University, 1970) Scoffield, John ErnestThe conversion of plant material to meat and milk by ruminants is one of the main ways in which the demand for energy and more especially protein for human consumption is met. While research in soil, plant and animal sciences is all more or less relevant to this conversion process a considerable amount of the agricultural research effort in Australasia has been directed more specifically to the grazing situation. Much of this work has been concerned with specific components of the grazing ecosystem such as the factors limiting pasture production (Brougham 1968), the definition of those plant factors contributing to nutritive value (Butler et al. 1968; Minson 1968), animal nutrition (Moir 1968) and pasture establishment (Swain 1968). While such research is basic to the understanding of the processes operating within a grazing system it must be complimented by a recognition of the interactions which exist within such grazing ecosystems and the way in which such interactions can affect interpretation of evidence from isolated parts of the grazing ecosystem. For example, the adoption of defoliation systems based on evidence from experiments of which grazing animals are not an integral part is often difficult to reconcile with the reality of having to graze a more or less fixed number of animals on a fixed area of land over a long period of time (Campbell 1969). In an effort to take account of the interactions which may invalidate conclusions based on evidence from component parts of the grazing ecosystem, the "whole-farm" approach to experimentation has been evolved. However in many cases such experiments have been designed to study the importance of different management factors on animal production from a given area of land (McMeekan 1961; Willoughby 1968) rather than to study the inter-relationships occurring between the soil, plant and animal components of the ecosystem. For example there is little information available on these inter-relationships from over 150 experiments of this kind carried out in Australia, evaluation of treatments having been carried out almost entirely in terms of animal production (Allden 1968).Item The effects of grazing management on pasture and bull production over the late-autumn to early-spring period : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Applied Science at Massey University(Massey University, 1998) Coutinho, Henrique BarbieriThe Massey University Tuapaka farm has been operating a bull beef enterprise for 15 years. During this period, late autumn grazing management has been based on a rotation length of 50 days in order to save pasture for the winter. However this intent is seldom achieved, leading to low pasture cover at the end of the winter and low liveweight gain in early-spring, which in turn compromised final bull slaughter weights The objective of this research was to design and evaluate winter grazing management systems based on pasture condition targets and to compare the outcome with the normal Tuapaka management. The aim was to maximise pasture growth rate and animal liveweight gains in late-autumn in order to winter heavier bulls at higher pasture covers than the traditional Tuapaka grazing system. Wintering heavier bulls at the target pasture cover (1800-2000 kg DM/ha) the winter grazing management would focus on maintaining pasture cover around 2000 kg DM/ha throughout the winter in order to reach early-spring with an average pasture cover around 1700-1800 kg DM/ha. This way the grazing management in this period would again target sward conditions for high net pasture accumulation and liveweight gains. The trial was conducted at the Tuapaka bull unit, Massey University, from 1 April to 30 September 1997. It compared three contrasting managements, involving a total of 165 bulls stocked at 2.6 bull/ha. Treatment I followed a predetermined grazing plan based on a predicted the average pasture growth rate, the animal requirements needed to achieve performance targets, and on pre- and post-grazing pasture mass targets (2700-2800 kg DM/ha and 1500-1600 kg DM/ha for late-autumn and early-spring, and 3000-3200 kg DM/ha and 1100-1200 kg DM/ha for winter). Treatment 2 was managed according to the same pre- and post-grazing targets, except in this case post-grazing covers were monitored daily, and the bulls shifted when the post-grazing targets were achieved. No supplement was considered for Treatments 1 and 2. Treatment 3 followed traditional Tuapaka management, based on 50 day rotation over the autumn and winter, and 30 day rotation in August and bulls set stocked in September. Hay was fed as required in winter at the rate of 120.6 kg DM (pasture equivalent) per hectare. The initial pasture cover and bulls liveweight did not differ between treatments. Results showed a significant difference in average pasture cover (P <0.1) over the autumn, although no difference was found in pre and post-grazing cover, apparent daily dry matter intake, and net herbage accumulation. Over the winter, Treatments 1 and 2 pasture cover did not differ, and both were significantly (P <0.001) higher than Treatment 3. Pre-grazing cover was significantly (P <0.01) different between all treatments, while there was no difference between Treatments 1 and 3 in post-grazing cover and apparent daily dry matter intake, and both were lower (P <0.001) than Treatment 2. Net pasture accumulation of Treatment 1 did not differ from Treatments 2 and 3, however there was a significant difference (P <0.05) between these two last ones. In early-spring, Treatments 1 and 2 pasture cover and post grazing cover did not differ and were higher (P <0.001) than Treatment 3. Pre-grazing pasture cover was different (P <0.01) between all treatments. Net pasture accumulation of Treatments 1 and 2 did not differ and both were higher (P <0.05) than Treatment 3, while the average apparent dry matter intake of Treatments 1 and 3 were similar and both were different (P <0.05) from Treatment 2. The overall liveweight gain (0 84 ± 0.02, 0.87 ± 0.02, 0.74 ± 0.01 kg LW/head/day for Treatments 1, 2, 3 respectively) and liveweight (354.7 ± 3.54, 359.8 ± 3.65, 335.6 ± 3.27 kg LW) did not differ between Treatments 1 and 2 but both were significantly (P <0.001) different from Treatment 3. Total pasture production was significantly different (P <0.10) between Treatment 1 (6147 kg ± 369.34 DM/ha), Treatment 2 (7062 kg ± 319.86 DM/ha), and Treatment 3 (5277 ± 334.08 kg DM/ha). The total pasture production of Treatments 1 and 2 were 16 and 30% higher than Treatment 3. The extra pasture production per 100 kg DM/ha of increase in pasture cover was 1.64 and 3.38 kg DM/ha/day for Treatments 1 and 2 respectively. It was concluded that it is possible to improve both pasture production and bull beef performance when grazing management is based on pre and post-grazing pasture targets, and the practical implications of this were discussed.Item Studies of grazing behaviour by lactating cows during winter, spring and summer : a thesis presented in partial fulfillment of the requirements for the degree of Master of Applied Science in Animal Science at Massey University(Massey University, 1999) Watson, Lisa AThe work outlined in this thesis was intended to study the grazing behaviour of lactating cows during winter, spring and early summer, and the effects of maize silage supplementation during winter. It also derived monthly rising plate meter equations over the period of the experiments, in order to assist with the estimation of cow intake and sward characteristics. Supplementation influenced the quantity and relative proportions of grazing, ruminating and idling times. Total grazing times were 546 vs. 615-min./day, and total rumination times 403 vs. 333-min./day for supplemented and non-supplemented cows respectively. Substitution of pasture for maize silage occurred, with reductions in grazing time averaging 26-minutes per kg DM eaten as maize silage. Rumination values per kg of total DM eaten were similar at 29-minutes (supplemented) and 27-minutes (non- supplemented). Intake rate of pasture was not affected by offering maize silage as a supplement, but grazing time was reduced. Cows preferred to graze during daylight hours, spending 47-57% of daylight hours grazing irrespective of daylength. Grazing activity peaked after milkings, and before dusk. Autumn and spring calved cows were grazed together in two experiments in the spring and summer of 1998. Stage of lactation had no effect on bite rate, bite weight, and intake rate ot herbage. Grazing times were related to metabolic requirements, and grazing behaviour was similar for cows which had calved in autumn or in spring. Times for ruminating and grazing were similar for heifers and mature cows, with similar components of day and night-time grazing. Heifers have a lower intake rate (23 vs. 27-g DM/min), and smaller bite weights (423 vs. 507-mg DM/bite) without a faster bite rate (58 vs.56-bites/min). Heifers also ruminated for longer per kg DM eaten, with similar ruminating times to mature cows (380 vs. 380-min/cow/day), despite their smaller daily pasture intake (12.9 vs. 15.3-kg DM/cow). It is suggested that the grazing behaviour of heifers is influenced by social factors, such as their dominance position in a herd. Monthly rising plate meter equations were derived between July 1998 and February 1999. When used to rank pastures for grazing order, the importance of the slope rather than the intercept was demonstrated. However when the rising plate meter was being used to compare pasture with required target values (such as average farm pasture cover, and post-grazing herbage mass), the intercept was also important, to give an accurate pasture mass value.