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Item Genetic and genomic studies of production, composition, and processability characteristics of milk from dairy sheep : a thesis 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, 2024-10-20) Marshall, Ana CarolinaThe main objective of this study was to perform genetic and genomic studies of sheep milk production, composition, and processability, particularly concerning cheese-making aptitude (milk coagulation properties) of sheep milk. The milk traits were investigated in a flock of 169 lactating ewes producing on a pasture-based system in Masterton, New Zealand. The total yield during the 2021-2022 season was 86.1 kg/ewe in 130 days of milking after the suckling period. The effects of animal factors on the lactation curves, and on milk composition and processability (milk coagulation properties, individual laboratory cheese yield, and heat coagulation time) throughout the season were investigated and discussed. Stage of lactation significantly (p < 0.05) influenced processability. In late lactation, the rennet coagulation time was longer, the curd at 30 minutes after rennet addition was softer, and milk heat stability was lower. In addition, milk protein polymorphisms were shown to influence milk composition and protein composition. Particularly, heat stability was affected by β-lactoglobulin polymorphism. The milk processability traits were also significantly associated with protein composition. The heritability estimates for milk production, composition, and processability traits ranged from 0.12 to 0.48. The genetic correlations obtained indicate that genetic improvement of this flock for higher yields of fat, and protein, and for lower somatic cell score, should indirectly improve milk coagulation traits in this flock. However, other traits such as milk pH, percentage traits (protein, casein, and lactose percentages), ratio of casein to protein, calcium, and ratio of casein to calcium were more strongly correlated with processability. The genome-wide association study performed on 149 dairy sheep genotyped with 50K SNPs Bead Chips, revealed a total of 87 SNPs and 55 candidate genes across Ovis aries autosomes 2, 3, 6, 16, 18, 20, 25, and 26. The genetic architecture of milk coagulation traits was similar to that of the ratio of casein to calcium, pH, lactose, and the ratio of casein to protein. The genetic correlations and identification of potential genes associated with the control of these milk traits provide valuable insights for the selection of superior dairy sheep in New Zealand. The findings of this thesis need to be validated with a systematic large-scale recording scheme before developing a selection index for dairy sheep populations in New Zealand.Item The impact of bale vs. crop grazing over winter on the welfare of dairy cattle farmed in Southland, New Zealand : 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, 2024) Latimer, Bella RoseIntensive winter grazing of pregnant non-lactating dairy cattle in Southland New Zealand often leaves cows in wet, muddy and rainy conditions with minimal shelter. Management on winter crops, such as kale, involves using high stocking rates to maximise utilisation and encourage cows to eat down to the ground, leaving bare soil that easily turns into mud. This has led to welfare concerns, as these conditions leave cows unwilling to lay down and may impair thermoregulation. Lack of rest can result in frustration and stress, and prolonged thermoregulatory challenge can result in cold stress, which are negative experiences that can impair welfare. While it is less efficient due to lower yields of dry matter/hectare compared to crops, it is thought that bale grazing (management on pasture with access to hay bales) may alleviate some of these issues and improve the welfare status of cows over winter. Therefore, this study aimed to assess the impact on lying behaviours and thermoregulation when dairy cows are managed on a kale crop compared to bale grazing over winter. Eighty pregnant non-lactating dairy cows were managed on either a kale crop or using bale grazing (n = 40/group) for winter 2022. Data collection was divided into two stages. In stage one, lying behaviours were monitored for the first month of winter (27 days) in relation to weather conditions. After this, during stage two, 60 out of the 80 cows (20 bale grazing cows, 40 kale crop cows, n = 10 groups per treatment) went onto replicated experimental plots of either kale/bale grazing for in-depth, behavioural analysis of lying and thermoregulatory behaviours/parameters for two days. Hygiene scores (measure of coat cleanliness on a 3-point scale) were obtained before and after each stage. Live weight and body condition scores were obtained before and after stage one and again just before calving. Inferential statistics were only calculated during stage two due to the lack of treatment replication in stage one. During stage one, lying times were similar for both treatments (kale crop = 8.7 hours/day, bale grazing = 8.9 hours/day), whereas kale crop cows transitioned between lying and standing more often (15 vs. 19/day) and took more steps than bale grazing cows (2,327 vs. 2,045/cow/day) on average. Rain and/or cold temperatures reduced lying times, transitions and steps for both treatments, resulting in rebound lying behaviour when conditions improved. This was more pronounced in the kale crop cows. During stage two, conditions were cold and dry. Kale crop cows lay down less than bale grazing cows (P = 0.013) and transitioned significantly more often between lying and standing (P = 0.019) on day one. However, this was likely attributed to a very low space allowance on day one. Bale grazing cows spent more time in comfortable lying postures (P = 0.022), were observed ruminating more (P = <0.001), remained cleaner (P = 0.004), had higher rump and thigh skin temperatures (P = 0.007) and higher infrared nose temperatures when lying (P = 0.048) than the kale crop cows. The surface for the kale crop cows became more compacted (P = 0.008) and got muddier (higher mud/boot score; P = 0.051). Overall, bale grazing cows appeared more comfortable than kale crop cows, which may be attributed to the greater thermal comfort and the provision of drier lying surfaces at a lower stocking rate.Item Genetic variation in surface temperature measured using infrared thermography and genetic associations with production traits in grazing dairy cattle : a thesis presented in partial fulfilment of the requirements for the degree of Master of Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2023) Douie, Jessica SophieHeat stress negatively impacts the production and reproduction of dairy cattle, and it is likely to worsen with increasing global temperatures due to climate change. Infrared thermography measured skin temperature could potentially be used as an indicator trait for heat stress in cows since it might correspond to the amount of heat dissipation. The aim of this research was to obtain infield skin temperature measurements for the eye, muzzle, and udder in dairy cows using infrared thermography in order to determine whether there is genetic variation in the skin temperature between cows in a dairy herd. Secondly, estimates of genetic correlations between skin temperature and economically important traits like milk yield were obtained. Thermal images and herd test records were obtained for 225 cows belonging to a once-a-day, spring calving dairy herd at Massey University’s dairy farm 1 in Palmerston North, New Zealand, during the 2022-23 production season. Breed, lactation number, and predicted milk yield were determined to significantly affect the average udder temperature. Holstein-Friesian × NZ Jersey crossbreds had the greatest average udder temperature as well as cows with higher lactation numbers and higher predicted milk yields. These results may be indicative of either higher producing cattle exhibiting greater udder temperatures and/or cows with greater udder temperatures exhibiting greater heat dissipation ability. The heritability estimates for infrared thermography measured eye, muzzle and udder temperature were low to moderate at 0.20, 0.24 and 0.39 respectively. The genetic correlations between the temperature and production traits were all positive and weak to moderately strong, with the exception of eye temperature with milk and protein yield. The estimates for the genetic parameters determined in this study indicate that increased skin surface temperature could be selected for without compromising production yield. These findings, if validated in a large-scale follow-up study would enable estimation of breeding values for udder temperature that could be incorporated into a selection index aimed at improving heat tolerance in dairy cattle.Item Measurement of spatial distribution of cattle dung under high and low stocking densities using remote sensing : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Agricultural Science at Massey University, Manawatū, New Zealand(Massey University, 2023) Dewhurst, ZacharyRegenerative pasture management is increasingly being practiced in New Zealand and encompassing a range of principles which generally focus on using diverse plant species to maximise photosynthesis and strategically use grazing livestock, with an overall aim of improving soil health. An example of regenerative pasture management is undertaken on Mangarara Farm, a non-irrigated sheep and beef farm located in Elsthorpe in central Hawkes Bay. Mangarara farm focuses on having higher pre and post-grazing pasture biomass than more conventional practices and grazes these pastures at higher stocking density. In theory, this grazing practice leads to more pasture trampling into the ground and more even dung distribution than conventional grazing practices. A new measurement method was developed in this study to test whether there is a change in the spatial distribution of cattle dung under regenerative management compared to conventional management. This method used a drone fitted with a red, green and blue (RGB) camera to identify and spatially map dung patches following grazing in a defined area (cells) on Mangarara farm. The research trial compared conventional and regenerative management using low and high stocking density. The control grazing (conventional) had a low stocking density of 6 Angus heifers moved every four days. In comparison, regenerative grazing had a high stocking density of 57 Angus heifers moved multiple times daily. The novel drone method was validated against a systematic measurement approach to assess the accuracy of the drone in detecting dung patches, compared to the systematic manual marking of dung patches using a survey-grade Trimble GPS to manually mark every dung patch within the cell. The results showed that the drone detected for all cells a mean of 57% of the dung patches within the cells. Data analysis revealed that multiple key factors affected the drone accuracy, including trees, pasture height and the amount of bare soil and it is recommended that lower pasture height and less bare soil present will minimise variation in future measurements. The same drone method was then used to compare the spatial distribution of dung under regenerative and conventional management. The results showed a significant difference between the median number of dung patches/ha for regenerative and conventional management. The analysis showed that the dung was not randomly distributed throughout the cell and that the regenerative management had slightly less clustering than the conventional management, indicating that the dung was more evenly distributed through the cell under regenerative management. The results from this study have shown that a drone fitted with an RGB camera successfully detected the spatial distribution of dung. However, some key limitations were identified, including wet soil conditions, bare soil and pasture height, which made it difficult to identify the dung due to a lack of colour contrast with the pasture and/or muddy soils. Dung with a higher liquid content was also difficult to delineate as one or several dung patches. Despite these limitations, this novel drone fitted with an RGB camera method offers a cheaper alternative to the traditional labour-intensive method of measuring dung distribution via the grid method and provides scope to measure dung distribution under a range of topographies such as hill country. This new method provides an opportunity for more research on the distribution of dung under different grazing management conditions and offers the potential to improve our understanding of soil nutrient distribution and nutrient loss risk.Item The gross composition, fatty acid composition, and processability of milk from cows milked once and twice a day under New Zealand grazing conditions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, Massey University, Palmerston North, New Zealand(Massey University, 2023) Sanjayaranj, InthujaaIn New Zealand, milking once a day (OAD) is practised by some farmers, with the majority of farmers milking twice a day (TAD). Once-a-day milking provides several benefits such as reduced labour cost, improved labour efficiency, improved health and reproductive performance of cows, and additional employment opportunities for farmers. Once-a-day milking causes a reduction in milk yield and modifies milk composition by increasing the fat and protein percentages. The main aim of this thesis was to study the effect of OAD milking on the gross composition, fatty acids composition, and processability of milk. To achieve this, the milk from 232 cows from a OAD herd and 182 cows from a TAD herd were collected in a full season in early, mid-, and late lactation. The samples were analysed for milk composition and fatty acid composition using Fourier-transform mid-infrared (FT-MIR) spectroscopy. Calibration equations for individual and grouped fatty acids were developed using FT-MIR calibrator software. Milk coagulation properties (rennet coagulation time, curd firming rate, and curd firmness) were analysed using a Formagraph. In addition, a SNP (rs109421300) in the diacylglycerol acyltransferase 1 (DGAT1) region on bovine chromosome 14, which is associated with a higher fat percentage in milk, was selected to study its association with fatty acid composition. Solid fat content at 10°C (SFC₁₀), a parameter that predicts butter hardness, was calculated using an equation developed from the proportions of fatty acids. The proportions of de novo synthesised fatty acids (C8:0-C14:0) were significantly higher, and the proportions of preformed, long-chain fatty acids (mainly C16:0 and C18:0) were lower in milk from cows milked OAD compared with cows milked TAD. Milk coagulation properties were superior for Jersey cows compared with Holstein-Friesian and Holstein-Friesian × Jersey cows milked OAD and TAD. The CC genotype of SNP rs109421300 was associated with higher fat yield, fat percentage, protein percentage, and SFC₁₀. Milk from OAD cows had lower proportions of C16:0 suggesting it would produce more easily spreadable butter. Selecting cows with the CC genotype would be suitable for the New Zealand dairy industry with the current payment system, however, the CC genotype was less suitable for making more easily spreadable butter. Overall, there were some significant differences noted between milk from cows milked OAD and TAD in terms of fatty acid composition and processability.Item Understanding the variations in grazing and rumination behaviours and their associations with production parameters in individual grazing dairy cows : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Animal Science at Massey University (Manawatū) New Zealand(Massey University, 2023) Iqbal, Muhammad WasimThis thesis aimed to understand: 1) the accuracy of an accelerometer-based sensor to monitor grazing and rumination behaviours in dairy cows; 2) grazing and rumination behaviour patterns and time budgets over 24 hours; 3) potential factors to influence grazing and rumination behaviours; and 4) effects of grazing and rumination behaviours on production parameters. To do this, data including, but not limited to, grazing time, rumination time, measures of cow performance (e.g., milk production and composition, body weight and body condition score), days in milk, and breeding worth index of 162 grazing dairy cows were collected for three consecutive lactation seasons (2018-2021). The analysis was performed on individual study years and results were reported separately for each year. First, the accuracy of AfiCollar, an accelerometer sensor-based automated device to monitor and record grazing and rumination behaviours in dairy cows was evaluated for a grazing-based system. Spring-calved lactating cows (n = 48) wearing AfiCollar were continuously visually observed for 8 hours (9 am to 5 pm) to quantify minutes per hour spent grazing and rumination. The behaviours being observed were also recorded with the AfiCollar and compared with visual observations using Pearson’s correlation coefficient (r), concordance correlation coefficient (CCC), and linear regression. A strong association was found between the data collected by AfiCollar and the data obtained through visual observation for grazing time (r = 0.91, CCC = 0.71) and rumination time (r = 0.89, CCC = 0.80) with a significant linear relationship between both datasets (p<0.05). Furthermore, variations in the temporal patterns (min/h) and time budgets (% min/day) of grazing and ruminating behaviours recorded using AfiCollar were evaluated in spring calving lactating (n = 162) Holstein-Friesian (HFR), Jersey (JE), and Holstein-Friesian Jersey crossbreed (KiwiCross, KC) cows in their different lactations (1st, 2nd, 3rd, 4th), and with different breeding worth index values (103151). A repeated measure design was performed in SAS using PROC MIXED considering the fixed effects of breed and lactation, the random effect of individual cows, and hours of the day as repeated measure to evaluate their effects on hourly patterns and time budgets of grazing, rumination, and idling behaviours. Regardless of the seasonal variations and feed consumed, cows spent most of their daytime grazing (with peaks around dawn and dusk) and most of their nighttime ruminating. Grazing and ruminating patterns were similar between cows from different breeds and lactations, however, JE cows grazed slightly longer than HFR and KC cows; and first-lactation cows grazed slightly longer than mature cows in their later lactations. The onset and cessation of grazing activity by the cows were adjusted according to varying day lengths by season. In addition, a general linear (PROC GLM) mixed model was fitted to test the effects of days in milk, breeding worth, breed, lactation year, individual cow, season, feed, and their interactions on variations in grazing time, rumination time and their relationship. Results indicated that grazing time varied among breeds in Year-2 and Year-3 and among lactation years in Year-1. Rumination time differed between breeds in only Year-3, and it remained the same within lactation years. Grazing time and rumination time varied among different seasons that were related to varying supplementary feeds. Days in milk, breeding worth (except Year-3), and the individual cow had effects (P<0.05) on grazing and rumination times. Grazing time and rumination time had a negative relationship with each other that varied between different seasons but remained the same among different breeds and lactation years. The variance in grazing and rumination times was mostly explained by individual cows (up to 24%), season (up to 12%), and feed (up to 8%). Moreover, results also showed that grazing and rumination times had positive associations with milk yield, fat, protein, and solids. Grazing time had negative and rumination time had positive associations with liveweight, while both grazing time and rumination time had negative associations with body condition score. Grazing time explained up to 1%, and rumination time explained up to 7% of the variance in milk yield, milk fat, protein, and solids. AfiCollar can reliably monitor grazing and rumination behaviours in dairy cows, however, its accuracy can be improved for a grazing-based system. The animal itself, the season, and the feed are the potential sources of variation in grazing and rumination behaviours and should be considered for management decisions to address the animal’s behavioural requirements. Grazing and rumination behaviours are moderately correlated with performance parameters and explain a small proportion of variance in animal productivity.Item Identification of potential welfare indicators for commercially farmed King salmon (Hāmana, Oncorhynchus tshawytscha) : a scoping review to inform the development of a national code of welfare : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University, Manawatu, New Zealand(Massey University, 2022) Norris, Izabella MareeAquaculture – the cultivation of marine plants and animals – is one of New Zealand’s fastest growing primary industries. A major contributor to the growth of New Zealand’s aquaculture industry is the farming of King salmon (Oncorhynchus tshawytscha). Parallel to the growth of the aquaculture industry is an increasing interest in the welfare of farmed fish from people in the industry, government, and public. Under the Animal Welfare Act 1999, fish are considered sentient beings capable of experiencing positive and negative emotions. However, unlike other animals under the Act, fish do not have a Code of Welfare to formally guide farmers to meet their obligations as animal carers under the Act. In order to develop a Code of Welfare for farmed fish, there needs to be an understanding of current and future state of the New Zealand salmon farming industry along with an evaluation of potential areas within production systems that may influence fish welfare, and identification of potential indicators of farmed salmon welfare. The New Zealand salmon farming industry use freshwater and marine-based operations to farm King salmon. Juvenile salmon are reared in freshwater hatcheries until they have reached an acceptable weight and/or stage of smoltification before being transferred into grow-out cages. Smolt are grown out in net cages, situated within either freshwater hydro-canals or coastal bays of the South Island, until they reach a harvest weight of ~4kg. At harvest, farmed salmon are stunned and slaughtered using methods such as Aqui-S and carbon dioxide immersion, manual and automatic percussion, and electrical stunning. Brain spiking is also used to euthanise broodstock prior to stripping. The Five Domains Model was used as a guide to evaluate areas of potential welfare impacts within New Zealand salmon farming systems. In terms of nutritional impacts (Domain 1), management of feed withdrawal regimes and factors associated with underfeeding may negatively impact salmon welfare. Appropriate water quality parameters are crucial for the maintenance of adequate environmental living conditions (Domain 2). Water quality parameters that may influence salmon welfare include water flow rate, temperature, oxygen saturation, carbon dioxide concentration, ammonia concentration, and salinity. Impacts on salmon health (Domain 3) may arise from the contraction of infectious bacterial diseases, physical injuries, and the development of spinal deformities. Lastly, in Domain 4, salmon welfare may be impacted through interactions with humans (e.g., handling stress during handling events), other non-human animals (e.g., aggressive interaction with conspecifics or presence of predators), and the environment (e.g., limited ability to exercise agency within barren and confined environments). A scoping review of globally published literature relevant to measures of salmon welfare was conducted to identify potential indicators of farmed salmon welfare. The scoping review identified a total of 112 potential animal- and resource-based indicators of farmed salmon welfare from 60 articles. There was a clear focus on the use of survival-critical indicators reflecting welfare impacts in Domains 1-3 (nutrition, health, and physical environment). A limited number of situation-related indicators (Domain 4) were identified. Of the identified indicators, a large proportion were classified as animal-based indicators sampled post-mortem. These indicators can only provide evidence of a previous experience in the animal assessed. To create a reliable and holistic assessment of farmed salmon welfare, contextual information is required for appropriate application and interpretation of welfare indicators with regards to affective experiences and a range of indicators across Domains 1-4 should be used in combination to capture all possible welfare impacts. The 112 unique welfare indicators identified and the understanding of their collective value to the welfare of commercially farmed salmon in New Zealand presented in this review provides industry, government, and policy makers the necessary information to develop regulations and on-farm welfare assessments.Item Investigation of ewe and lamb mortality on a commercial farm in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2021) Capdevila Ospina, Kimberly GiselleOn-farm ewe mortality is an important issue that impacts the productivity and profitability of the New Zealand sheep systems. Additionally, it raises potential concerns regarding ewe welfare and consumer perception implications related to the increase of ewe deaths. Ewe mortality ranges from 2.0 to 20.8% per annum and is increasingly recognised as an important problem on New Zealand sheep farms. This thesis established the ewe mortality rates, period of risk and the association between productive parameters and ewe deaths on a commercial sheep farm in New Zealand, with further investigation into the causes of ewe and lamb mortality around lambing. This study utilised a cohort of 1789 two-tooth ewes on a commercial sheep farm located in the Waikato region. Data were collected from the start of mating (March 2019) to weaning (December 2019), a period of 262 days. Additionally, the ewes were monitored daily over a period of 24 days, both prior to and during the first weeks of lambing, by a researcher who utilised a drone for greater access when possible. Results showed that over half the ewe deaths during the study period occurred during the lambing period, hence, this was the period of highest risk for ewe death. Twin and triplet-bearing ewes had higher risk of mortality than single-bearing ewes. During the lambing period, being cast was the main cause of ewe death (66%), while other causes included vaginal prolapse and dystocia. Change of conceptus-adjusted live weight (CALW) at mating and BCS at ram removal tended to be lower in the ewes that died, however, further investigation is required to establish productive parameters associated with ewe mortality. The findings of this thesis suggest that it might be possible to reduce ewe mortality around lambing, especially in multiple-bearing ewes, by daily monitoring to identify and resolve cast ewes. If this were done it is likely that the ewe and therefore her future lambs would be saved. This study only included one farm in a single year, however, and the repeatability of these results should be evaluated in further years and in other flocks.Item Genetic and genomic studies of animal welfare and environmental traits in dairy cattle : 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) Ariyarathne, Hewa Bahithige Pavithra ChathurangiNew Zealand dairy cows graze outdoors throughout the year and are exposed to a wide range of weather conditions also their excreta are dispersed in the paddock. There is an emerging interest in whether between-cow genetic variation could contribute to environmental sustainability and improved animal welfare. The initial objectives of the study were 1) to estimate genetic parameters of rectal temperature (RT) as an indicator of heat stress (HS), 2) to identify gene regions associated with HS through genome-wide association studies (GWAS), and 3) to estimate response of genetic selection for low HS on milk production using conventional selection in grazing dairy cows of New Zealand. The genetic variance of RT estimated in 776 mixed-breed cows at two Massey University experimental dairy farms was very low due to insufficient environmental stress on sampling days. This outcome diverted the topic of study to the genetic basis of milk urea concentration (MU) and efficiency crude protein utilisation (ECPU) and their potential role in improved environmental sustainability. The new study was conducted considering MU as the trait of interest. Additionally, the possible reduction of urinary nitrogen (N) excretion by genetic selection for low milk urea N concentration (MUN) was determined. The heritability estimated for MU (from 0.27 to 0.49) and ECPU (from 0.02 to 0.41) using a random regression model in 634 mixed-breed cows indicated that these traits can be genetically manipulated by direct selection. Estimates of genetic correlations between MU and yield of milk, fat, crude protein, lactose, and liveweight (LWT) in each day of ii lactation were mostly positive and imply that selection for reduced MU would result in reduced production and LWT of cows. The GWAS identified six novel genes (GMDS, E2F7, SIAH1, SLC24A4, LGMN, ASS1) associated with MU that function in protein catabolism, urea cycle, ion transportation and N excretion. This suggests that genomic selection for MU is possible, however, the results should be validated with a larger sample size. Selection index theory was used to estimate correlated responses for different selection indices including MUN with different relative emphasis (RE). The predicted genetic responses per cow per year of the current index were 16.4 kg milk yield (MY), 2.0 kg fat yield (FY), 1.4 kg crude protein yield (CPY), -0.4 kg LWT and -0.05 mg/dl MUN. Including MUN in the selection index with 20% negative RE resulted in annual responses of 5.4 kg MY, 1.6 kg FY, 1.0 kg CPY, -1.1 kg LWT and -0.17 mg/dl MUN. The total N predicted to be excreted in the base year was 336.5 kg/ha. When stocking rate was adjusted by changes in milk production and cow feed requirements, 10 years of selection with a selection index not including MUN increased total N excretion to 338.9 kg/ha. A selection index with 20% negative RE for MUN increased total N excretion to 341.6 kg/ha, and genetic gain in production of milk protein per hectare was reduced, thereby reducing farm profits. The results of this thesis indicate that inclusion of MUN in a selection index with negative RE is not an effective pathway to reduce farm-level N leaching and carbon footprint.Item The management of miniature horses at pasture in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy (without specialisation) at Massey University, Manawatū campus, New Zealand(Massey University, 2020) Goh, Sheen YeeStudies on the demographics, feeding management and health care practices of Miniature horses in New Zealand have yet to be conducted. Thus, the aim of this study is to describe the demographics, feeding management and health care practices of Miniature horses in New Zealand. To achieve the aim of this study, an online survey was conducted using the Qualtrics Survey Software. There were 232 valid responses from respondents who kept 1,183 Miniature horses, representing approximately one third of the New Zealand Miniature horse population. Miniature horses were kept for leisure and companionship (56%), competition (35%) and for breeding (7%). The median number of Miniature horses kept by owners for leisure and companionship was significantly lower (two horses) than those kept for competition (six horses) or for breeding (ten horses) (p<0.05). The majority (79%) of Miniature horses were kept at pasture on low (<1,000 kg DM/ha) to moderate (~2,000 kg DM/ha) pasture masses across seasons. Pasture access was more commonly restricted by respondents during spring (60%), summer (60%), and autumn (55%) than in winter (43%). The majority (n=173/198, 87%) of respondents practiced pasture-restriction strategies such as strip grazing (n=118), temporary use of a paddock with little grass (n=99), confinement for part of a day in a stable or yard (n=94), turning out horses to graze in the early morning only (n=42), or fitting a grazing muzzle (n=24). Another pasture restriction strategy cited by respondents (n=15) was provision of a track system. Respondents indicated the mode daily number of hours of stabling was 7-12 hours (n=57/195, 29%). Miniature horses kept primarily for competition were stocked at a significantly higher stocking density (13 horses/ha) compared with those kept for leisure and companionship (10 horses/ha) or for breeding (12 horses/ha) (p<0.05). The overall median stocking density was 10 horses/ha, (~1,100 kg live weight/ha). Although the stocking density appeared to be high, on a live weight basis, it was comparable to the stocking density of other classes of equine livestock. In addition to feeding on pasture, most owners provided the horses with additional feed (n=194/232, 84%). Additional feedstuffs were hay (n=180), chaff (n=130), premixed concentrates (n=117), fermented forages (n=51), and other types of feed (n=33) such as oats, copra, soy, molasses, and sugar beet pulp. Respondents (n=200/214, 93%) dewormed their Miniature horses between two and four times annually as a routine preventive measure (n=156/199, 78%), and of the respondents who vaccinated their Miniature horses in the last year (n=41/199, 21%), tetanus and strangles vaccines were the most administered vaccine types (n=20/41, 49%).