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The uneven distribution of grazing cattle on pastures and rangelands has been of concern to livestock managers since the very early days of grassland science, not least because of the effects of grazing patterns on ecosystem functions and the sustainability of farming systems. Mountainous terrain imposes additional limitations for free-range grazing animals; which may avoid using vegetation at higher altitudes, on steeper slopes, or at greater distance from drinking water. Consequently, areas that are more easily accessible might be overgrazed, potentially leading to diminished ecological functions and reduced productivity. In recent years, animal personality theory has suggested that individual animals do not behave in the same way, and instead display consistent and distinctive sets of behaviours or ‘personality’. Animal personality could explain the distinct grazing patterns reported for free-range cattle, where individual animals have preference for certain habitats over others as a result of their behaviour. Preliminary studies have also reported associations between cattle gene regions (i.e., quantitative trait loci) and indexes that describe terrain use, suggesting the potential for genes that might explain variation in the grazing personality of beef cattle. This thesis contains the following chapters: A literature review about grazing behaviour and personality (Chapter 1). While grazing lands can offer a diverse range of forages, individuals within herds appear to prefer to graze some habitats and not others. They can have consistent differences in grazing patterns and occupy specific spatial domains, whilst developing tactics and strategies for foraging that are individual specific. Accordingly, in this chapter, a new understanding of grazing personality was developed. This entailed the development of a ‘grazing personality model’ (GP-model) that accounts for the personality of individual animals and for the collective behaviour of herds. The GP-model postulates that the grazing personalities of ruminants and other large herbivores are determined genetically and tempered epigenetically in interaction with the social and biophysical environments of the cattle. They may also reflect the emotional state of animals. While the selection of one grazing personality may be adequate for homogeneous pastoral systems, the design of herds with a range of grazing personalities that are matched to the habitat diversity may be a better approach to improving the distribution of grazing animals, thus potentially enhancing ecosystem services and maximizing productivity. An investigation of whether the movement of cattle and potential measures of their grazing personalities might be determined genetically, was undertaken in chapter 2. Genetic variation within the glutamate metabotropic receptor 5 gene (GRM5 ), a ‘grazing gene’ candidate was investigated. Associations between variation in that gene and variation in grazing personality behaviours (GP-behaviours) were tested with mature cows (n = 303) under free-range management during winter grazing in the steep and rugged rangelands of New Zealand. Grazing behaviours were calculated using data from global positioning system (GPS) tracking collars and, satellite-derived data. Eight GP-behaviours were fitted into mixed models to ascertain their associations with variant sequences and genotypes of GRM5 . Three new GRM5 variants (A, B and C ) were discovered and six possible genotypes were identified in the cattle studied. The mixed models revealed that A was associated (P < 0.05) with elevation range, home range and movement tortuosity. Similarly, GRM5 genotypes were significantly associated (P < 0.05) with home range and movement tortuosity, while trends towards association (P < 0.1) were revealed for elevation range and horizontal distance travelled. Most of the GP-behaviour models were improved when corrected with the ‘cow age-class’ factor and the results suggested that grazing personality might be stable when cows reached 4 years of age. Home range and movement tortuosity were not only associated with GRM5 variation, but also negatively correlated with each other (r = -0.27, P < 0.001). Thus, there seems to be a genetically determined trade-off between home range and movement tortuosity that may be useful in beef cattle breeding programmes that aim to improve the grazing distribution and utilisation of steep and rugged rangelands. The results of Chapter 2 suggested that differences in grazing patterns are associated with nucleotide sequence variation in GRM5 . Association analyses require large datasets to detect genotype-phenotype associations, hence, most large-scale studies aiming to identify behavioural linkages with grazing genes typically apply random sampling from existing setups without a priori control over the genotypic composition of the sample. This can lead to unbalanced experiments with over or under representation of any given group analysed. An alternative approach (Chapter 3) was used to perform a discriminant analysis of a balanced dataset that was generated by under-sampling the larger dataset (n = 303) described in Chapter 2. In this analysis, a training dataset of mature cows (n = 80) that equally represented five of the six GRM5 genotypes and four farms were selected. The GP-behaviours were derived from 5-min GPS relocations measured over 15 d and the analysis aimed to select a combination of GP-behaviours that assist the identification of specific GRM5 genotypes, and to investigate behavioural differences between cows of various genotypes of this ‘grazing gene’. Two sets of grazing behaviours were selected to build quadratic discriminant models (QDMs) that achieved 87% of accuracy in ascertain GRM5 genotype with a training balanced dataset. An ‘exploration discriminant model’ built with the GP-behaviours related to elevation, slope and exploration correctly predicted the genotypes of 85% of the individuals of a testing dataset that were not included in the model’s training. MANOVA and ANOVA analyses highlighted the relative importance of GP-behaviours to discriminate between GRM5 genotypes and showed behavioural differences between cows of various GRM5 genotypes. The results extend the list of key behaviours linked to GRM5 in agreement with genotypephenotype associations between GRM5 and GP-behaviours reported in chapter 2 and in the literature. In conclusion, sets of key GP-behaviours might be useful for predicting the variation in putative ‘grazing genes’ and QDMs applied to small-scale experiments with balanced designs seems to be a promising approach for behavioural genetics. Overall, this research proposed a model for individual and collective grazing personalities for cattle. The analysis suggested consistent differences between individuals associated with GRM5 variation. Furthermore, linkages between bovine GRM5 and key grazing behaviours may characterise specific genotypes and assist with their identification. The research provides a conceptual model of grazing personality and experimental evidence suggesting possible applications of behavioural genetics to potentially optimise the distribution of beef cattle in steep and rugged terrain. More research is however needed to validate these findings.

The purpose of the work described in this thesis was to demonstrate an animal-based solution to an environmental problem currently facing the pastoral agricultural sector. High levels of nitrogen loading as a result of high concentrations of urea in the urine of dairy cows have been associated with widespread environmental degradation, such as reduced water quality and N2O emissions. Known linear relationships exist between the concentrations of urea in urine and urea in milk, with milk urea nitrogen (MUN) concentration considered a moderately heritable trait. The primary hypothesis of this research was that animals considered low for milk urea nitrogen breeding values (MUNBV) would have reductions in urinary urea nitrogen (UUN) concentration that could be associated with reductions in environmental impact. The primary objective of this research was to provide supporting evidence for the primary hypothesis. Multiple experiments were conducted, and are detailed across several chapters in this thesis, testing the primary hypothesis and providing supporting evidence as to potential physiological mechanisms that may explain any observed relationships. Chapter 3 presents an experiment using 48 lactating Holstein Friesian × Jersey cows considered divergent for MUNBV in a grazing setting and found that per unit decrease in MUNBV the concentration of UUN decreased by 0.67 ± 0.27 g/L. Chapter 6 reports the results of an experiment conducted as a metabolism crate study using 16 lactating Holstein Friesian × Jersey cows considered divergent for MUNBV. The experiment detailed in Chapter 6 reported a consistent 28% reduction in average UUN concentration between high and low MUNBV cows when consuming a ryegrass diet and was thus in agreement with the findings of the experiment presented in Chapter 3. Chapter 7 reports a plot of the diurnal pattern of the results from the experiment presented in Chapter 6 and suggests that low MUNBV cows when consuming ryegrass consistently for all hours of the day had a lower concentration of UUN than high MUNBV cows on the same diet. The results reported in Chapters 3, 6, and 7 provide supporting evidence to accept the main hypothesis of this thesis and conclude that low MUNBV cows do have reductions in UUN concentrations. Reductions in UUN concentrations from low MUNBV cows can be associated with reductions in N losses to the environment and therefore lower environmental impact from low MUNBV cows compared with high MUNBV cows when consuming ryegrass diets. The experiment presented in Chapter 4 investigated the grazing behaviour of the cows used in the experiment presented in Chapter 3. The results presented in Chapter 4 suggest that a one-unit decrease in MUNBV resulted in a 0.05 ± 0.02 increase in mastications per prehension, indicating that low MUNBV cows have a greater level of oral processing than high MUNBV cows and have altered grazing strategies and nutrient acquisition. Increased oral processing from low MUNBV cows is likely to alter rumen fermentation dynamics by resulting in faster rumen outflow rates. The hypothesised differences in rumen function as a result of different oral processing is considered the likely explanatory factor behind the observed phenotypical differences between dairy cows considered divergent for MUNBV reported in this thesis. Dietary interactions presented in Chapters 3, 6, and 7 explored the effects of grazing either a plantain (Plantago lanceolata L.) or ryegrass (Lolium perenne L.) based diet and the interactions with MUNBV. Inconsistent results were found by diet where the effects of MUNBV were detected for cows consuming ryegrass diets but not detected when cows consumed plantain diets. Chapters 4 and 7 provide evidence that the lack of effect from MUNBV on plantain diets is likely due to the ability of plantain to be easily masticated, therefore allowing the high MUNBV cows which are less efficient at oral processing to achieve similar oral processing and subsequent rumen function to the more efficient low MUNBV cows. It is speculated in Chapter 6 that the MUNBV values are based on a genetic model whose parameters are based on cows grazing predominately ryegrass white clover pastures and therefore may need re-parameterisation for different diet types. The acceptance of the main hypothesis of this thesis and identification of a likely mechanism causing the observed differences in MUNBV achieves the purpose of these studies to demonstrate an animal-based solution to an environmental problem.

The purpose of this thesis was to identify the functional changes at the rumen, individual animal and whole-farm scale when FB is used to supplement a ryegrass-based sward during lactation. A review of the literature (Chapter 2) explored the potential of FB to improve the feed base of the farm system and advance low infrastructure grazing systems which are common to New Zealand. However, the review also suggested greater biological, tactical and financial risk may be associated with growing and feeding FB on the milking platform, and the potential net advantage/disadvantage and had not been well defined in grazing dairy systems. Of primary concern was the incidence of acute and sub-acute ruminal acidosis (SARA) which has been underestimated across the herd in confinement and pastoral dairy systems worldwide. The incidence of SARA in cows transitioned to FB using industry-approved methods, and alternative FB feeding strategies to reduce SARA was highlighted as an area requiring further evaluation. In the first experiment (Chapter 3), the effect of feeding FB during early lactation on milk production and milk fatty acid composition of grazing dairy cows was explored. Sixty Friesian × Jersey cows were blocked into six groups of 10 cows, and groups randomly allocated to three replicates fed either 18 kg DM/day of ryegrass herbage (H), or 14.4 kg DM/day of ryegrass herbage + 4 kg DM of harvested FB bulbs (FBB). There was no advantage to milk production when 30% of a ryegrass-based herbage diet was substituted for FB bulb although, this also indicated that FB might provide an adequate substitute for herbage during periods of feed deficit. Supplementation of herbage with FB increased (P < 0.001) de novo synthesis of saturated fatty acids (particularly; lauric, myristic and palmitic acids) and reduced substrate availability of unsaturated fatty acids for ruminal biohydrogenation which reduced (P < 0.001) the content of long-chain and unsaturated products in milk. While the sward's chemical composition differed between treatments, the fatty acid content of herbage was not different (P > 0.1). The altered biohydrogenation end-products in milk and the high soluble-carbohydrate content of FB compared with herbage indicated altered rumen microbial communities and rumen function. The second experiment (Chapters 4 & 5) was split into two chapters to evaluate two objectives. The first objective was to assess the industry recommended method for transitioning lactating dairy cows (+ 0.5 kg DM FB/day) to moderate (40% DMI) amounts of FB on changes in rumen fermentation, pH and risk of SARA. In a cross-over design, eight rumen cannulated cows during early lactation were fed one of two diets either; herbage only (HO) or 60:40 ryegrass herbage + FB bulb (FBH). Response variables were analysed as a 3x2 factorial arrangement of FB adaptation stage (Stage 1: transition day 1-12, Stage 2: adaptation day 13-17, Stage 3: post-adaptation day 18-20) and dietary treatment. Two animals experienced severe SARA (pH < 5.6 for >180 min/d), one during each period, they were closely monitored but were able to self-correct rumen pH without intervention. Across each treatment, the FBH diet increased estimated DMI (measured by calibrating sward height with sward mass), but milk production was similar to the HO diet. Ruminal pH of cows fed FBH declined below HO between 0100 h and 1200 h each day even during stage 3 of adaptation, which may have reduced the microbial degradation of structural carbohydrates and limited the milk response to FB. The large content of water-soluble carbohydrate content of FB prevented rumen pH from stabilising within 20 days of adaptation and elevated the risk of SARA in specific individuals. An extended period of transitioning and low FB allocation may be needed to prevent the risk of SARA grazing dairy cows supplemented with FB. The objective of Chapter 5 was to evaluate the effect of supplementing spring ryegrass with moderate amounts (40% of total DMI) of FB on digestive and ingestive processing. We hypothesised that the decline of ruminal pH caused by supplementing ryegrass with FB would reduce the rumen function and microbial degradation of ryegrass. Following day 20 of adaptation (Chapter 4), the eight ruminal cannulated cows' rumen contents were removed at 0000 h, weighed and returned to the rumen and cows were fasted for ~10 h overnight before rumen contents were again removed and weighed. Samples determined particle comminution, pools of fermentation-end products and fractional neutral detergent fibre degradation between each bailing session. Minced samples of ryegrass and fodder beet were incubated separately, in sacco over 20 h on day 20 of each period (between 0400 – 0000 h), to evaluate DM disappearance. Each cow's total jaw movement was recorded on day 16 and 18 of adaptation to FB to identify changes in behaviour (grazing, ruminating and idling) and oral processing (mastication and prehension). While calibration of pasture mass form height reported in Chapter 4 indicated the FBH treatment consumed greater DMI than HO, estimation of DMI from energy output in maintenance, milk production and loss of body condition indicate DMI between treatments was similar (P > 0.10). In addition, the rumen pool of DM, ADF and NDF measured at the first (0000 h) rumen bailing, also reflected DMI when calculated from animal output and maintenance. Cows fed FBH spent 86 min/day longer ruminating and chewing intensity while ruminating increased 38% compared with those fed HO, while grazing time declined 20 min/kg DM of FB eaten. While the fractional degradation of neutral detergent fibre was similar between treatments, the FBH diet reduced the total VFA pool compared with HO following fasting (3.67 versus 4.03 mol), due to reduced ruminal concentrations of acetate and propionate. Despite greater rumination and chewing intensity, the rumen pool of large particles (> 2 mm) following fasting, declined 28% in cows fed FBH compared with those fed HO. In sacco DM disappearance of ryegrass following 20 h of incubation also declined 19% (P < 0.01) in the FBH treatment. The decline of VFA pool, reduced particle comminution and DM disappearance of ryegrass in sacco support the hypothesis that supplementing grazing dairy cows with moderate (40% of DMI) amounts of FB reduces the microbial activity of the rumen and limits the milk response to FB. The results suggest minimal advantage and high risk to rumen function and animal welfare of individual cows supplemented with FB. The third experiment (Chapter 6) evaluated the effect of a combined substrate containing ryegrass and increasing proportions of FB bulb (0, 15, 30 and 50 % of DM) on cumulative gas production and fermentation-end products in vitro. The objective of this study was to evaluate the dose-dependent response to supplementing ryegrass with FB bulb on the formation of fermentation end-products and gas production in 100 ml glass syringes. The total gas accumulated increased with the proportion of FB incubated (P < 0.05). The concentration of butyrate and propionate increased, while the concentration of acetate declined (P < 0.01), following 24-h of incubation. Production of carbon dioxide (CO2) formed from buffering VFA and methane (CH4) formed from fermentation, were calculated using stoichiometry. The percentage of CH4 declined yet, the total accumulation of CO2 and CH4 increased with the amount of FB included in the substrate. The effect of treatment on gas production diminished (P > 0.10) when the greater OM content of FB was accounted for, which indicate that while FB may reduce fractional CH4 emissions, total methane emission may increase compared with ryegrass, due to the greater fermentable organic matter content of FB bulb. Chapter 7 aimed to characterise changes of rumen pH, milk production and total discomfort from FB and define practical feeding strategies of a mixed herbage and FB diet. The deterministic, dynamic, and mechanistic model, MINDY, was used to compare a factorial arrangement of FB allowance, herbage allowance (HA), and allocation time. The FB allocations were 0, 2, 4 or 7 kg DM/cow per day (0, 2, 4 and 7FB, respectively) and HA were 18, 24 or 48 kg DM/cow per day above ground. All combinations were offered either in the morning or afternoon or split across two equal meals. Milk production from 2FB diets was similar to control but declined 4, and 16% when FB increased to 4 and 7 kg DM. MINDY predicted that 7FB would result in SARA and that rumen conditions were sub-optimal even at moderate FB allocations (pH < 5.6 for 160 and 90 min/d, 7 and 4FB respectively). Pareto Front analysis identified that splitting the 2FB diet into two equal meals fed each day alongside daily HA of 48 kg DM/cow provided the best compromise between high milk production and low total discomfort. However, due to low milk response and high risk of acidosis, we conclude that FB is a poor supplement for lactating dairy cows. In Chapter 8 a multi-component, whole-farm modelling approach was used to predict milk solids (MS) production and the economic farm surplus (EFS: operating surplus – adjustments) over two seasons (2016-2018) for an irrigated farm in Canterbury (South Island) and a non-irrigated farm in the Waikato (North Island), of New Zealand. The financial risk of the dairy business was measured using stochastic modelling in which the ratio between mean return on assets (ROA) minus an assumed 5% risk-free ROA, and the standard deviation of ROA was calculated from 300 combinations of climate, milk and feed price, land appreciation and interest rate. Four scenarios of autumn and spring supplementation of pasture were considered at each geographical location; imported maize silage (Base), maize silage crop grown on the platform (MSC), FB crop is grown on the platform (FBC) and FBAC a FB crop with an outbreak of acute (1% stock fatality) and SARA (5% decline of feed intake). Crop yield of FB increased with irrigation (21 versus 23 t DM/ha; irrigated and dryland, respectively) and was greater than maize silage (19 versus 21 t DM/ha; irrigated and dryland respectively). The DM yield of maize silage increased with the dryland system due to the warmer climate in the Waikato region of New Zealand (NZ). The MSC scenario improved EFS 5.8 % compared with Base when introduced to either the irrigated or the dryland system. The predicted response to MSC reflected a combination of greater milk production, lower feed expenses and shorter crop rotation compared with either Base, FBC or FBAC. While FBC increased EFS by 4.8% compared with Base under irrigation, EFS was similar to Base under dryland conditions ($2,711 and $2,759/ha, respectively). The limited advantage of growing FB under dryland conditions reflect reduced herbage supply due to the extended crop duration of FB compared with maize silage (14 versus 11 months between grazing of herbage). Model predictions suggest FBAC would reduce EFS by 6.5% (irrigated) and 7.1% (dryland) compared with Base, due to reduced milk production and livestock sales. In the absence of any adverse health risks, farm performance from supplementing FB crop was comparable to maize silage under irrigated conditions. However, in dryland conditions, and when the potential economic cost of acute and sub-acute ruminal acidosis is considered, there is little advantage from growing FB on the milking platform. While there is some support that minor allocation of FB with herbage will improve animal production, the novel methods of feeding and grazing FB in NZ increase animal welfare risk of individual animals within the herd, preventing the elimination of SARA risk when feeding FB to support lactation. Besides a few recent studies, previous research of FB feeding systems in NZ has focused on the herd as an experimental unit. However, the dynamics of feeding FB to individuals within the herd are variable, and the risk of SARA caused by supplementing ryegrass-pastures within commercial dairy systems of NZ may be underestimated. Further research should focus on factors responsible for individual risk to SARA such as competition, grazing and feeding behaviour, epithelial function, and morphology and rumen fermentation. Attention is needed when feeding FB to large herds in minimal infrastructure systems which prevent individualised feeding of FB as the variation of FB and herbage intake between individuals and days alter the allocation of FB to the remaining individuals within the herd. The results from this thesis suggest feeding small amounts of FB may help improve milk production and reduce feed deficits; however, the risk of SARA increases with FB allocation. Profit comparisons indicate limited financial incentive to growing FB on the milking platform to supplement ryegrass during early and late-lactation compared with lower-risk alternatives such as maize silage. In conclusion, from a rumen, individual animal and farm systems perspective, there is no advantage to supplementing grazing dairy cows with fodder beet to support lactation.

The objectives of this research were to determine the impact of supplementing pasture-based diets with forage crops, previously used to mitigate winter N losses, on dry matter intake (DMI), milk yield, milk composition, and N utilization from dairy cows. Three supplementation studies integrating fodder beet (FB, Beta vulgaris L) or oats (Avena sativa) with perennial ryegrass (Lolium perenne L.)-white-clover (Trifolium repens L.) pasture were carried out in early or late lactation. Further, modelling studies were conducted to compare the effects of these crops on the productivity and profitability of irrigated dairy farms in Canterbury, New Zealand. The aim of the first experiment was to determine the effect of FB or oats on dry matter intake (DMI), milk production and N utilisation of grazing dairy cows in early lactation. The experiment was a comparative study of four spring feeding regimes with sampling replication via animal (n = 12 cows/treatment). Forty eight early lactation dairy cows were fed 3 kg DM/cow/d of fodder beet, oats forage or oats silage as supplement + 18 kg DM/cow/d of pasture for 21 days using a completely randomized design. Total apparent DMI was greater (P < 0.001) for grazed oats forage (OF) and oats silage (OS) compared with pasture only (Control) or fodder beet (FB). Cows substituted pasture for supplement maintaining a similar metabolisable energy (ME) intake (226± 3) across treatments. Consequently, there was no effect (P = 0.865) of supplement on milk yield or milk solids yield (P = 0.436). However, supplementation with FB resulted in lower (P < 0.001) urinary N concentration (4.7 g N/L) compared with CON, OF and OS (5.9, 6.0 and 5.5g N/L) respectively. The higher urinary N concentration in CON, OF and OS is likely to be due to higher N intake (630, 725 and 657 g N/cow/day respectively) compared to FB (589 g N/cow/day). These results showed there was no increase in milk production due to high substitution rates and similar energy intake. However, low protein supplements such as fodder beet were effective at reducing N intake and improve N use efficiency for milk production. Questions remained regarding the animal response to FB or oats when supplemented to cows with a lower energy demand in late lactation. The aim of the second experiment (autumn) was to determine the effect of FB or silage (ryegrass or oat) supplementation on DMI, grazing behavior, milk production and urinary N excretion on grazing dairy cows in late lactation. Fifty-four late lactation dairy cows were supplemented 4 kg DM of fodder beet (FB), oats silage (OS) or ryegrass silage (RGS) in addition to allocation of 12 kg DM/cow/d above 1500 kg DM/ha residual as perennial ryegrass and white clover pasture. The experiment was carried out over 21 days. Total DM intake was similar across treatments (P = 0.69), but milk production for cows supplemented with OS was lowest (1.01 kg MS/cow/day) compared with the RGS (control) or FB treatment that had similar milk yield (1.11 and 1.13 kg MS/cow/day respectively). The lower milk yield of OS compared with other supplements could be explained by the low ME of the supplement as well as the greater pasture mass offered to those cows. Autumn is an important time of the year to reduce N losses and supplementing with FB in late lactation reduced (P < 0.05) apparent N intake, milk urea N, (37, 40 and 44 g/dL) and spot urine N concentration (2.8 versus 3.9 and 4.0 g/L) compared to feeding OS or RGS respectively. These results demonstrated that cows on pasture offered low CP, and high-energy supplements, such as FB, during late lactation can sustain milk production while lowering N surplus. Further considerations were needed to understand why no milk response to FB was observed and to determine whether the quality of the product (milk composition) alters even though the quantity (milk yield) does not. In the third experiment, the purpose was to more clearly understand the lack of response in the first experiment by including grazing behavior measurements as well as the the effect of milk quality. Thirty-six early lactation dairy cows were fed perennial ryegrass-white clover (control) and supplemented 3 kg DM of FB or OF for 21 days. Again, as with experiment one there was no difference observed in total DMI (16.1 ± 0.52 kg DM/cow/day) or milk solids yield (1.9 ± 0.8 kg MS/cow/d) between treatments. Cows in each treatment spent similar amount of time grazing (413 ± 38.5 minutes/cow/d). There were supplement effects on milk quality. Milk fat and lactose (%) increased by feeding FB. The increase in fat % appeared to be due to increased short chain fatty acids. Though FB reduced the more valued long chain, (and some medium chain) fatty acids compared with the RGS control. Milk protein % was unaffected by supplement, but feeding FB increased casein concentration along with the minerals calcium and phosphorus. This suggests that cows supplemented with FB in early lactation may have been Ca deficient. As with previous experiments, cows that were supplemented with FB had lower N intake and lower urinary N concentration (2.4 g N/L) compared with OF and CON (4.3 and 3.1 g N/L). This resulted in, FB cows having a higher N use efficiency (36.2%) compared with OF and CON (29.5 and 29.8%, respectively). Given that there were little apparent milk yield benefits to supplementing with FB or oats during these short term grazing studies, follow up questions arose regarding the economic value of trying to integrate winter crops on the milking platform. To determine the feasibility and profitability of including winter supplements on the milking platform, results from experiments 1,2 and 3 were incorporated into a commercial decision support tool, FARMAX. Four scenarios were compared to a baseline farm system representing a Canterbury dairy farm. The scenarios were 1. Feeding FB only in spring, 2. Feeding FB (grazed) in autumn and drilling oats after grazing FB, which is grazed in spring, 3. Feeding oat forage only in spring and the last scenario was feeding oat silage in autumn. The results of the simulation showed that FB & OF (Autumn & Spring) scenario had the highest milk production (460 kg MS/ha) compared to (422, 418, 440 and 436 kg MS/ha) for baseline, FB spring, OF and OS scenarios respectively. Also, FB & OF (Autumn & Spring) scenario had lower cost per kg MS ($3.7 kg MS). The most profitable system at a $6.00/kg MS was FB & OF (Autumn & Spring) scenario on the milking platform. Results showed that despite there being no difference in herbage diet quality, supplementing FB & OF (A & S), scenario increased total DM offered and consumed (6.2%), thereby increasing milk production with 8.3% compared to (-1.6, 4.1 and 3.2%) for FB spring, OF and OS scenarios respectively with FB spring scenario that had the lowest milk production. Resulting in an increase of 10.1% in the gross margin profit/ha for FB & OF scenario compared to (6.0 and 4.4%) for OF and OS scenarios with the FB spring scenario having the lowest. In the short term grazing studies, supplementing pasture-fed dairy cows with FB or oats did not increase total DMI in early or late lactation due to high pasture substitution rates (SR) and similar energy intake. However, supplementing FB had effects on milk quality in both spring and autumn experiments. Only FB supplement lowered N intake (in spring) and improved N use efficiency for milk production as well as consistently lowering spot urine N concentration. Oats was more likely to reduce milk production when offered ensiled and may be more appropriate as a dry cow supplement. In both short term feeding and economic modeling, integrating FB supplement has value in sustaining milk production while lowering N losses in urine

In this study, three experiments were conducted to determine factors influencing social dominance in lactating, grazing dairy cows. Additionally, we investigated the effect of separating cows, based on social dominance, on milk production and grazing behaviour. Dominance in all experiments was quantified by calculating a dominance value (DV), which was measured through observation of wins and losses between cows in social interactions. A dominant cow which won all, or most, of its interactions would have a DV range between 60-90, a mid-ranking cow a DV between 30-60 and a subordinate cow which lost all, or most, of its interactions having a DV of 0-30. In New Zealand pastoral-based dairy farm systems, no information exists on the impact of social hierarchy, and its disruption, on animal productivity. In experiment 1 (Chapter 3), an observational study was carried out to identify factors determining social dominance of grazing dairy cows and the subsequent relationship with milk production. Recognition of dominance among peers was evaluated for three groups of cows differing in stocking rate and herd size. The three groups of Friesian × Jersey cows used in this study were, a large group of 189 cows stocked at a medium stocking rate (4.2 cows/ ha; MSR), a small group of 34 cows stocked at a high stocking rate (5.0 cows/ ha; HSR), and another small group of 29 cows stocked at a low stocking rate (3.5 cows/ ha; LSR). All cows (n=252) ranged in age from 2 to 11 years old. Cow liveweight (LW) ranged from 340 kg to 648 kg. In each of the three groups, LSR, MSR and HSR, the DV was positively correlated with age (r = 0.646, 0.349, and 0.442 respectively, P

Abstract: Selection for the trait residual feed intake (RFI) is an emerging tool for cattle producers to manage feed costs within the beef industry. This study explored whether cattle habitat use and activity on extensive pasture-based systems in the dry mixedgrass of Alberta differed between cattle with divergent molecular breeding values (MBV’s) for RFI. Neither predicted RFI group (low vs. high) nor individual animal MBV score were found to explain cattle movement rates, resting time, or habitat use. Instead, timing of grazing (early, middle and late growing season grazing), pasture type (native mixedgrass, tame, or wetland plant community types), forage metrics (quantity and quality) and distance to water were the factors regulating cattle activity, habitat use, and performance. Cows had significantly higher activity levels (greater movement rates and lying bout frequency, less time spent lying down) early in the grazing season. Lying time decreased with increasing pasture size across all pasture types and native grasslands alone, and decreased with increasing biomass and exposure to better quality (less fibrous) grasses and forbs. Cow performance metrics during the growing season (weight and back fat gain, as well as calf weaning percentage) were not affected by MBV for RFI, activity measures or most habitat metrics studied. However, those cows spending less time within 200 m of water were found to wean larger calves and gain more back fat over the grazing season. I conclude that improving pasture-based cow/calf production through selection for low RFI requires more research into genetic markers that better predict RFI under these complex, native pasture environments. Our research showed that changing environmental conditions affected animal activity and habitat selection, and this consequently affected their performance. These results support that the identification of MBV markers unique to extensive production systems may be necessary to improve cow/calf production through selection using RFI.

Supplementary feeds are offered to grazing dairy cows to increase dry matter and metabolizable energy intakes; however, offering feed supplements reduces pasture dry matter intake, a phenomenon known as substitution. The objective of this research was to understand variations in grazing behaviour in pasture-fed cows and the effects of supplementation on grazing time and feeding intake rate throughout the day and to investigate humoral profiles of factors known to be associated with intake regulation in monogastric species and quantify their role in ruminant species. Grazing occurred predominately during daylight hours, with minimal grazing during the hours of darkness. Distinct grazing bouts were evident post sunrise and pre-sunset. Supplementation reduced time spent grazing; however, this was an accumulation of reduced grazing time throughout the day and was not restricted to the period following the consumption of supplement, as fundamentally, the profile of grazing behaviour in supplemented cows followed the same pattern as unsupplemented cows. The effects of supplementation on time spent grazing differed depending on the time of day. Time spent grazing linearly reduced with increasing supplement in the a.m., whereas, time spent grazing was unaffected by supplementation during the pre-sunset grazing bout, irrespective of supplement level or timing of sunset. The differences in grazing behaviour during the major post-sunrise and pre-sunset grazing events lead to the hypothesis that different factors regulate dry matter intake at these times. In the a.m., products of digestion and associated physiological factors regulate grazing behaviour. Whereas, in the p.m., environmental cues (i.e. sunset) override physiological signals that regulate grazing behaviour in the a.m. to ensure maximal grazing occurs prior to darkness, irrespective of supplementation or energy balance status. Humoral profiles of factors implicated in intake regulation in monogastric species were similar in the dairy cow. Humoral factors associated with a fasted or pre-prandial state were elevated and declined after meal initiation, whereas, factors indicating a change from a negative to a positive energy state increased after meal initiation. Despite the similar humoral profiles, the profile of plasma ghrelin during the major p.m. feeding event differed from its reported decrease in concentration after feeding, establishing a unique profile for ghrelin. Plasma ghrelin increased in the p.m. despite intensive grazing/feeding and cows being in a positive energy state prior to the p.m. feeding event, which had not been previously reported in ruminant species. The increase in ghrelin was coincident with an increase in the intensity of grazing/feeding that lead to the hypothesis that ghrelin increases in diurnal species ensuring animals maximise dry matter intake prior to darkness, which is a major environmental cue to cease grazing/feeding.

Sodium is an essential element for animal production, with >0.07% Na required in herbage DM for lactating ewes. Na however, is non essential for plant production. With Na concentrations decreasing with increasing distance from the coast, inland farming areas of New Zealand, including much of the high country are often sodium deficient for grazing livestock. In extensive grazing systems pasture quality and legume content of steep shady faces is often low due to poor pasture utilization. This project tested whether the application of salt (NaCl) could be used to attract sheep and enhance grazing, and so improve pasture utilisation, botanical composition and oversowing success of steep shady faces. Five experiments were conducted on small plots (up to 30x8 m) between December 2003 and May 2005. The aim was to determine the effects of salt, fertilizer and seed application on botanical composition and seedling establishment. All experiments were conducted on a predominantly steep (20-38°), south facing slope (600 m.a.s.l.) at Mt Grand Station, with a mean annual rainfall of 713 mm. Mt Grand Station is a sodium deficient (

Advocates of mixed grazing have argued that grazing habits of different animal species tend to be complementary rather than exclusively competitive. However there were few objective data for variation in pasture intake and diet selection among species grazing the same pasture or on the extent of variation in diet selection between animals of differing age within a species on which to base this assumption. In the three experiments in this study the objectives were to: compare species intake and diet selection in a range of sward structures; develop techniques that would enable grazing behaviour to be related to prevailing pasture conditions; test the hypothesis that the force required to sever individual bites may determine bite dimensions and resultant bite weight and intake rate, and differences in grazing strategy between animal species. Diet selection and intake of calves, lambs and kids, simultaneously, but separately, grazing four pasture masses (3000, 3800, 4500 and 5400 kgDM/ha) on a temperate ryegrass white-clover sward, were compared in the first trial. A common pasture allowance for all species was calculated at twice the interspecies mean maintenance requirement (0.5 JME/kg⁰.⁷⁵/d). Animal intake was estimated from faecal recovery using Cr₂O₃ as a marker corrected for diurnal variation. Diet composition and quality were measured in the extrusa (OE) obtained from oesophageal fistulae of four individuals of each species. A further four fistulated older goats and sheep were used to compare diet selection among animals of differing age within a species. Mean species intake rates were 77.8, 60.0 and 48.7 gDOM/kg⁰.⁷⁵/d for calves, lambs and kids respectively. Lambs were the only species where intake was not affected by pasture mass (PM). All species consumed a diet of similar quality (organic matter digestibility), however botanical composition while similar at low pasture masses differed increasingly as pasture mass increased. Dietary overlap suggested the species were more competitive than complementary when grazing intensively managed pastures. Pasture and animal measures in this trial were too imprecise and/or infrequent to enable species grazing strategies to be characterized. In the second experiment a technique involving short term grazing of pasture turfs cut from a ryegrass white clover pasture was developed to enable intake and bite variables to be related to sward structure. Two animals of each species progressively defoliated, in 4 grazing periods, 3 turfs of similar mass (4700 kgDM/ha) and composition. Intake rate (IR) of the sheep and goats was greater than that of the calves (124, 100 and 40 mgDOM/kgLW/min, respectively). Intake rate of sheep was insensitive to declining PM or pasture surface height While goat bite weight declined with both PM and surface height it did not effect IR. Goats exhibited an aversion for older vegetative leaf and preferentially consumed young leaf while cattle preferentially consumed the second to oldest leaf. Bite depths of cattle and goats were similar and shallower than sheep (2.9 and 2.7 vs 4.0cm respectively). It was concluded that this technique, with further modifications, was suitable for identifying causal relationships between sward structure, intake and bite variables. In the first trial of the final series of experiments pure perennial ryegrass turfs (surface area 0.lm² x 0.lm soil depth) were manipulated by clipping to produce 3 pasture heights (5, 10 and 15cm) x 3 pasture structures (varying in leaf to pseudostem ratio and bulk density). Six sheep grazed 4 turfs of each height and density fixed to a force plate. Mean peak bite force, bite weight, bite depth, bite area, bite volume and grazed stratum bulk density were calculated. Peak bite force increased with pasture surface height but significantly so only between 10 and 15cm. Pasture structure had no effect except on the 5cm pasture treatment with the highest grazed stratum bulk density. Bite depth and bite weight increased with pasture height and were not influenced by pasture structure at a constant height. Bite area was similar at all pasture heights, but decreased as grazed stratum bulk density increased. On short pastures (

A study was conducted to investigate partial preference for Trifolium repens and Lolium perenne, and the effect of relative heights of swards on the preference and selection of sheep and goats. Three Coopworth 1 year old ewes and three Saanen/Anglo-Nuvian male one year old goats were selected for the first experiment (November 1996) and three replacement animals of similar description for the second experiment (January 1997). The treatments consisted of a combination of 2 pasture species (grass, clover) and 3 heights (5, 9 and 13 cm), giving 12 paired contrasts, where each was a combination of two swardlets offered to one penned animal. Number of bites and dry matter removed were measured for each swardlet, as well as the total time allowed for grazing. At equal availability, both sheep and goats showed a strong preference for clover, both species removing between 67 and 78% clover from a clover/grass contrast. At varying height, within the same pasture species, both animal species preferred higher swards in grass contrasts. In clover contrasts goats had a stronger increase in intake with height than sheep, the percentage eaten from the longer sward for sheep was 56%, 59%, 81 % and for goats 54%, 72%, 88% at 13/13 cm, 9/13 cm and 5/13 cm contrasts, respectively. With combinations of pasture species and height, goats had a weaker preference for clover and stronger preference for height than sheep. In the 13 cm grass/altering clover contrasts, as clover height decreased to 9 and 5 cm, goats markedly increased the proportion of their intake from grass to 52 and 86 % respectively, while sheep only increased their intake of grass to 38 and 47 % respectively. Both sheep and goats had higher intake rates at the combinations of long clover/changing height grass than any other of the combinations tested. The trends observed in preferences were the same in both experiments, but more extreme in the second experiment. This may be related to the greater difference in digestibility between grass and clover in the second experiment. The conclusions of this study were contrary to popular belief. The within pasture species response of goats and sheep to changing height was very similar in grass monoculture. In clover monocultures goats showed a greater preference for the longer swardlet than sheep. In clover/grass and height combinations, sheep were willing to graze clover to a shorter height than goats, which switched to higher grass before sheep. The "preference for a mixture" concept was confirmed in this study for sheep and goats. It was not possible to support any given theory for selection of a mixed diet with complete confidence. It was suggested that a combination of the theories reviewed, involving the concept of "Maximum Ecological Fitness" could be a possible explanation for the behaviour observed. A model which illustrates the effect of changing grass/clover availability on ecological fitness was proposed.

The objectives of the research were to: achieve a method of grazing species comparison in which grazing behaviour would be unconfounded by stocking rate: to compare the grazing behaviour of cattle, sheep and goats under equivalent pasture conditions: to observe the interaction of animal species during periods of mixed grazing: and to define grazing strategies which would fit the observations. Three species of domestic ruminant (cattle, sheep and goats) were repeatedly observed during progressive defoliation of temperate, ryegrass/white clover pastures at an equal rate of disappearance of pasture mass (RDPM). Eight grazing experiments were conducted, each for a period of between 4 and 21 days, during winter, spring and summer. Animal intake was estimated from apparent disappearance of pasture mass and faecal recovery, using Cr₂O₃ as a marker. Diet composition and quality was measured in the extrusa (OE) obtained from oesophageal fistulae of six individuals of each species. RDPM was controlled at similar values across species (±13 kgDM/ha) in the range of 110-365 kgDM/ha/day over all experiments. It was concluded that RDPM was a suitable, if laborious, method to compare intake behaviour. Digestible organic matter intake (DOMI) of each species declined from a mean maximum, ad libitum value of 48.7 (cattle), 40.0 (sheep) and 47.3 (goats) gDOM/kgw·75 at the beginning of each experiment, to below 10 gDOM/kgW'75 at mean pasture masses (PM) of below 1300 kgDM/ha for cattle and sheep and below 2000 kgDM/ha for goats. The DOMI response was the result of a decline in both dry matter intake (DMI) and diet digestibility (DMD) during the grazing period. At PM above 1700 kgDM/ha cattle had a significantly (p

Two consecutive experiments were conducted to test a hypothesis that mixed grazing outcome is influenced by the type of stocking system applied. The objective of both experiments was to investigate the influence of co-grazing with sheep on cattle liveweight gain (LWG) under continuous (C) and rotational (R) stocking, where sheep weekly liveweight change under the two stocking systems was kept similar. In experiment I nine yearling heifers (266 ± 4.5 kg liveweight) and 27 ewe hoggets (54±0.9 kg liveweight) were continuously stocked for 19 weeks on an irrigated perennial ryegrass-white clover pasture (2.95 ha) maintained at a sward surface height (SSH) of 5cm by adding or removing additional animals in a fixed ratio (1: 1 W⁰.⁷⁵ cattle:sheep). An equal area of pasture was rotationally stocked by a similar group of animals where they received a new area of pasture daily and also had access to the grazed area over the previous 2 days. The size of the new area provided daily was such that the weekly liveweight change of rotationally co-grazed sheep was equal to that of those continuously co-grazed with cattle. Similar groups of animals were used in the second experiment with additional group of 9 heifers grazed alone on C and R pastures. Liveweight of animals was recorded weekly and final fasted weight was determined after 24-hour total feed restriction. SSH on both treatment swards was recorded daily. There were three intake measurement periods spread over the trial period. Organic matter intake (OMI) was predicted from the ratio of N-alkanes in faeces and herbage. Diet composition was determined by dissecting oesophageal extrusa samples. Grazing behaviour (bite rates and grazing time) were also recorded. The mean SSH for C pasture was 5.1±0.09 cm. Overall pre- and post-grazing SSH for R pasture was 15.9 ±0.12 and 5.6 ±0.07 cm, respectively. As determined by the protocol average daily LWG of sheep was similar between C and R (147 (±5.8) vs 138 (±6.7) g day⁻¹; (P>0.05). In contrast, cattle continuously stocked with sheep grew 200 g day⁻¹ slower than those rotationally stocked with sheep (800 (±41.6) vs 1040 (±47.7) g day⁻¹, P0.05). Differences in OMI followed a similar pattern to daily LWG. Mean daily OMI was 8.98, 6.24, 8.80 and 9.45 (±0.40) kg for CA-C, CS-C, CA-R and CS-R, respectively. Clover content of the diet of CA-C heifers was three times higher than that of CS-C heifers (30.7 vs 10.4 % OM; P

Over recent years, there has been a considerable increase in the area of lucerne grown in New Zealand, particularly that used for grazing. The total for conservation and grazing increased from 19,000 ha in 1947 to about 145,000 ha in 1968 (White, 1968) and it is expected that the figure will reach 200,000 ha by 1973. In the same manner, the proportion used for grazing rose from less than 10% in 1947 to more than 40% in 1966 and it is anticipated that this trend will continue into the foreseeable future. More recently, the importance of pure lucerne, especially in early spring, has become greater following the general trend of intensifying animal production through early weaning of lambs (Jagusch et al., 1970; Jagusch et al., 1971; Joyce et al., 1972; McConnell, 1972). One of the main aims of the trials reported in this thesis is to verify Professor K.F. O'Connor's theory that removing the apices of immature lucerne plants stimulates the growth of crown buds and at the same time enhances the growth of axillary shoots on the upper portions of the stubble. Results of such findings could prove to be valuable in future in view of the reported increase in the number of young lambs weaned on to lucerne pastures and noting also that the grazing behaviour of these animals differs markedly from that of the older stock. Further, it has been shown that leafy tops (stem apices) and immature lucerne or cool season growth are high in feed quality (Bailey et al., 1970; Jagusch et al., 1970; Smith, 1970; Jagusch et al., 1971). Although a few workers (O'Connor, 1970; Peart, 1970; McKinney et al., 1972) have attempted to provide balanced data on the performance of both animals and pastures in a grazing system, little is known about the individual plant responses to varying grazing behaviour, particularly its reactions to different periods of grazing and spelling. Lack of information on the above aspects prompted the cutting treatments described in this thesis to be designed and the experiments carried out. It is hoped that the principle of optimal growth and production or other relevant information discovered from the cutting trials could gain useful applications to a real grazing situation.