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Item Meat quality and fat characteristics of lambs finished on different summer forages : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2025-10-16) Phillips, HollyNew Zealand lamb production systems are typically based on grazing perennial ryegrass/white clover pastures; however forage quality and growth tend to be inconsistent over the summer period leading to reduced intakes and animal performance. Summer-active forage crops can be included in the farm system to provide a source of high-quality forage over this crucial finishing period. In addition to this, ensuring consistently high eating quality lamb meat is paramount to maintain and expand export markets, thus any change to production systems need to consider the impact on the meat produced. Whilst alternative forages to perennial ryegrass/white clover have been studied extensively for their agronomic characteristics and animal performance, less is known about the impact of an alternative forage on the value chain from farmer to processor and in particular characteristics that can impact the consumer such as meat quality. This is particularly the case with the relatively new forage brassica species, Raphanobrassica. This collection of studies conducted a comprehensive assessment of lambs grazing Raphanobrassica, Chicory, Perennial ryegrass/white clover (Chapters 3-7), Leafy Turnip, Red Clover and Perennial ryegrass/white clover + concentrate (Chapters 3-4). Studies utilised a replicated farmlet design and measured lamb growth, carcass production, meat quality, fat characteristics, volatile profile and conducted a consumer sensory evaluation. Lambs grazing alternative forages had increased lamb growth rates, carcass weights and dressing out percentages (Chapters 3 & 5). Using Raphanobrassica or Chicory resulted in greater per hectare lamb performance (liveweight gain and carcass weight produced per hectare) over the summer and autumn period. The two forage types had different factors driving this increase, with lambs fed Chicory having greater per head performance and Raphanobrassica able to support a larger number of grazing lambs per hectare due to superior forage growth in dry conditions (Chapter 5). Instrumental measurement of meat quality (pH, meat colour, shear force and water holding capacity) demonstrated small and inconsistent effects of forage diet (Chapters 4 & 6). Grazing alternative forages resulted in greater fat deposition (V-GR and intramuscular fat %) from faster growth and heavier carcasses. Changes in fatty acid composition were small and explained by the differences in IMF deposited (Chapters 4 & 6). Assessment of different grazing durations over summer and autumn (32, 35 or 67 days) showed that length of time grazing had a greater effect on meat quality and fat deposition than the forages themselves, with longer grazing durations associated with heavier carcasses, greater fat deposition and a fatty acid profile that was more saturated (Chapter 6). A stepwise analysis was used to assess the volatile profile of lamb meat, with 10 key volatile compounds differentiating the forage grazed and grazing duration. Aldehydes, alcohols and ketones (derived from lipid oxidation), sulphur compounds and hydrocarbons (non-lipid volatiles) were identified as potential markers for the forage treatments (Chapter 6). A consumer sensory panel identified meat from Chicory fed lamb as being less tender, however this can be explained by the larger carcass weights achieved on this forage type. Scores for overall liking for Raphanobrassica were dichotomous, potentially due to Raphanobrassica having more frequent rankings for greatest flavour intensity, indicating flavour intensity could be a stronger driver of liking for some consumers compared to others (Chapter 7). This research has shown that alternative forages to perennial ryegrass/white clover can be grazed by lambs over the summer period to improve animal production per head and per hectare without compromising the quality of meat produced for the processor or consumer.Item Bone development on the distal phalanx of New Zealand dairy cows : the link to lameness : a thesis presented in partial fulfilment of the requirements for the degree of Master of Animal Science, Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2025) Mohan, AthulClaw horn disruptions are important cause of lameness and affects cattle around world, causing major economic and welfare problems for dairy industry. Inflammation from an active CHD can lead to bone growth (exostoses) on the distal phalanx, which predisposes the animal to further CHD in future and damages the internal anatomy of the hoof. Previous quantitative studies have evaluated, using µ-CT, bone development on the distal phalanx of cows which are housed for most or all of the year, and identified that bone growth is associated with age, lifetime history of CHD and chronic lameness. The aim of the present study was to evaluate whether digital photography could be used instead of µ-CT to obtain linear measurements of exostoses and to find whether bone development was associated with age, claw type and lameness history in the lactation prior to culling in pasture-based cattle. Distal phalanxes (160) were collected from the hind feet of 40 dairy cows after slaughter. Digital photographs were then taken, and bone growth measurements were made at 4 locations near the flexor tuberosity (A to D) guided by the method using µ-CT. Modelling was then used to identify whether age, claw type and lameness history were associated with the average of the sum of measurements A to D across all four claws of an individual cow (Ave BG) and the highest sum of A to D for an individual claw within a cow (BG Max). Only minor modifications were necessary to the measurement method to account for the differences between µ-CT and digital photography, thus digital photography provides an economic alternative to the use of µ-CT to study bone development in the distal phalanx. An association was found between age and BG Max and Ave BG with a one-year increase in age being associated with BG Max increasing by 1.12 (95% CI: 1.03-1.21) times and Ave BG increasing by 1.09 times (95% CI: 1.04-1.14). Outcomes for history of lameness were also compatible with lameness increasing bone growth, with the point estimate for BG Max being 1.61 (95 CI: 0.88-2.95) (equivalent to 5 years of age effect) and for Ave BG being 1.25 (CI:0.89-1.78) (equivalent to 3 years of age effect). However, the data were also compatible with no biologically important association between lameness and bone growth. The majority of the differences between claws in BG Max and Ave BG were driven by differences in measurement D as 136/160 claws had zero values for measurements A, B and C but all claws had values > 0 mm for D. In all claws where the only measurement >0 was measurement D, the bone development appeared to be normal being smooth in appearance without any pointed edges or rough surfaces. Analysis of the effect of age on measurement D (in claws with A, B, C= 0), and on the sum of A, B and C was consistent with the hypothesis that the principal effect of age was through its impact on measurement D, as the effect of age on measurement was similar to its impact on BG max, and the analysis of age on sum of A, B and C was compatible with no effect. However, these are preliminary data, and this hypothesis needs more investigation.Item Effects of the protein source and content in milk replacers on bone and organ growth in lambs artificially reared from birth until six weeks of age : a thesis presented in partial fulfilment of the requirements for the degree of Master in Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2024) Desesquelles, Solene Nathalie StephanieThe objective of this study was to investigate if preweaning diets differing in protein source and content altered growth rates as well as bone and organ development in lambs artificially reared from birth until six weeks of age. Lambs removed within the first 48 hours from the dam were randomly allocated to one of the two rearing treatments; MP: milk-protein based milk replacer or WVP: whey and vegetable-protein based milk replacer. Four lambs from each treatment were slaughtered at two weeks of age while the remaining lambs were slaughtered at six weeks of age. Lamb live weight at two weeks of age did not differ (p > 0.05) between treatments. There were differences in bone morphology and organ growth, although milk protein-based milk replacer (MP) was associated with greater lamb live weight and average daily gain at six weeks of age (p < 0.05). From birth until six weeks of age, the type of milk replacer had no effect on stature measures and bone morphology (p > 0.05), meaning that early lamb bone growth is influenced by increases in live weight rather than the type of milk replacer used. Lamb development is driven by live weight gain however, lambs were observed only from birth until six weeks of age, which has limited the observation of live weight gain and thus, changes in bone morphology and organ weight. The differences in the preweaning diets may have altered the future developmental potential growth of bone and organs in lambs but this needs further investigation.Item An investigation of the genetic correlation of 200-, 400-, and 600- day weights between beef-on-dairy and beef calves : 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) McFarlane, Connie ElizabethThe expansion of the New Zealand dairy industry has led to an increase in the number of lower-value surplus calves. A mitigation strategy to increase the value of surplus calves is to have them enter the beef market. The aim of this thesis was to investigate the genetic connection between values generated in the dairy-beef progeny test and those generated by the beef progeny test. This was achieved, in part, by researching the genetic correlation between dairy weaning weight, 200-, 400- and 600-day weights in beef-on-dairy compared to beef calves. The data required for the research was collected in the National Dairy-Beef progeny test and the National Beef progeny test funded by Beef+Lamb NZ. Least squares mean for weaning weight, 200-day weights, 400-day weights and 600-day weights were obtained using a generalised linear model. A single-trait animal model was used to estimate genetic parameters, variance components and calculate heritabilities. A bivariate animal model was also used to estimate the genetic and phenotypic correlations between variables. The estimated heritabilities for beef-on-dairy cattle were lower than those generated from beef cattle, in particular, weaning weight (0.17 vs. 0.67) and 200-day weight (0.43 vs. 0.78). This difference may be due to maternal effects, management system differences and the focus of breeding programmes. The heritabilities for 400-day and 600-day were high in both beef and beef-on-dairy cattle, therefore, indicating that these traits are under greater genetic influence. The genetic correlations for growth traits were strong (ranging between 0.60 and 0.96) while the phenotypic correlations were generally lower than the genetic correlations (0.26 and 0.83) within beef cattle and beef-on-dairy cattle. Given these results, the study recommends using beef progeny tests to predict growth traits for both beef and beef-on-dairy systems. This will simplify the breeding process, reduce costs and will enhance the genetic merit of the calves entering the beef industry.Item Carcass and meat quality characteristics of Romney and three-quarter Wiltshire lambs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Palmerston North, New Zealand(Massey University, 2024) Rawidech, RawisaraSelf-shedding sheep breeds, like the Wiltshire, have been introduced into meat production systems in New Zealand to reduce costs such as shearing and crutching. However, there is limited information on the meat performance of Wiltshire-cross lambs. Therefore, this study aimed to assess carcass and meat quality attributes of Romney and ¾ Wiltshire lambs. Data were collected from Romney (n=11) and ¾ Wiltshire (n=12) ram lambs, managed and fed on pasture under the same conditions, and sent to slaughter, as one group when all lambs reached a minimum of 42 kg liveweight. Final on-farm liveweight, hot carcass weight and dressing-out percentage were obtained on the day of slaughter. Muscle and dissectible fat percentages, muscle-to-bone ratios for whole leg and femur, muscularity, and femur bone morphology were obtained from leg dissections. Objective meat quality assessments were conducted on a sample of the Longissimus lumborum muscle to obtain pH, colour, water-holding capacity, shear force value, intramuscular fat percentage and fatty acid composition. The start and, final on-farm liveweights and hot carcass weights of the ¾ Wiltshire lambs were heavier than Romney lambs (P<0.05). Muscle and intramuscular fat percentages, muscle-to-bone ratios and muscularity did not differ between treatments (P>0.05). The ¾ Wiltshire lambs had lower dissectible fat percentages and greater muscle weights surrounding the femur compared with the Romney lambs (P<0.05). The ¾ Wiltshire lambs had greater femur bone length, total bone content, density, cortical bone content and thickness, and bone stress strain index compared with the Romney lambs (P<0.05). However, total bone area, cortical bone density, and periosteal and endosteal circumferences of both treatments were the same (P>0.05). There was no difference between the two genetic differences in meat colour, water-holding capacity, shear force and fatty acid profile (P>0.05). The results suggest that the ¾ Wiltshire lambs produce carcass and meat quality characteristics that are comparable to Romney lambs when slaughtered at a similar age. Therefore, the use ¾ Wiltshire lambs will not negatively affect meat yield and meat quality and will not be disadvantaged when used in lamb meat production systems.Item The effect of weaning age on gastrointestinal epithelial development of calves in New Zealand : a histomorphological analysis : 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) Greig, AmeyDairy-beef calves born on New Zealand dairy farms are artificially reared and often weaned earlier than would occur under cow-calf beef production systems. Most weaning studies have focused on calves reared on concentrated diets for indoor systems and early (6-12 weeks of calf age) weaning systems. Weaning studies on artificially reared calves destined for grazing are limited and the effects of weaning age on gastrointestinal tract (GIT) development of dairy-beef calves reared on pasture are not known. This study evaluated the effects of milk-weaning at 10 (early) vs 20 (late) weeks of age on the histomorphology of the GIT of dairy-beef calves until 30 weeks of their age. The objectives of this study were to (1) evaluate differences in GIT epithelial development of early and late weaned calves and (2) evaluate whether differences (if any) persisted post-weaning. Male Hereford-Friesian calves (n=72) were sourced from two commercial dairy farms at three weeks of age and allocated to two treatments: early and late weaned. From the beginning of the study, all calves were kept outside (six calves per paddock; six paddocks per treatment) with free access to pasture (ryegrass clover mixed). A commercially purchased milk replacer (1 kg/day/calf; diluted in water to 7 L) was divided into two equal portions and fed twice daily using group feeders. Calves were weaned with a gradual reduction in milk replacer allowance beginning three weeks before designated weaning age. All calves were kept in their respective paddocks until humanely killed. Calves from each treatment were slaughtered across three different time points: 10 weeks, 20 weeks, and 30 weeks of age. At each time point 12 calves from each treatment (n=24) were slaughtered. Tissue samples from the rumen, duodenum, jejunum, and caecum were collected, processed to make histological slides, and analysed for histomorphological differences. The effect of slaughter age was significant for rumen ventral sac papillae length, duodenum villus width, jejunum crypt depth, and jejunum layer depth (essentially a combination measurement of villi length and crypt depth). The effect of weaning age was significant for caecum crypt depth, with early weaned calves having increased crypt depth across slaughter age. The interaction of weaning age and slaughter age was significant for rumen ventral sac papillae length, with early weaned calves having significantly greater papillae lengths (P<0.05) at slaughter week 20, but this difference did not persist post weaning (30 weeks). This study successfully reared and weaned calves at 10 and 20 weeks of age onto a pasture only diet without any major influence on histomorphology of their GIT observed.Item Venison and velvet production from Red and hybrid deer by one year of age : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Animal Science at Massey University, New Zealand(Massey University, 1996) Min, Byeng-RyelA grazing experiment was conducted at Massey University Deer Research Unit, Palmerston North, New Zealand during 1995, to study the effects of grazing chicory (Cichorium intybus), Lotus comiculatus and perennial ryegrass (Lolium perenne)lwhite clover (Trifolium repens) pasture upon the growth, voluntary feed intake (VFI), venison and velvet production of red and hybrid (0.75 red;0.25 elk) deer from weaning to slaughter at one year of age. The animals were randomly allocated to graze either chicory, lotus or pasture and grazed these forages during autumn and spring using a rotational grazing system, with each group balanced for genotype and sex. All groups were joined to graze pasture during winter, when chicory and lotus were dormant. 1. Few animals attained the target slaughter weight (50kg carcass or greater) when grazing pasture and spiker velvet antler weight was low at approximately 0.2 kg per stag. 2. In this study the greatest advantages obtained for specialist forages were for chicory. Carcass weight of deer grazing chicory was higher than for deer grazing pasture, due mainly to increasing autumn LWG and dressing-out percentage at slaughter, with a smaller response in spring LWG. The largest carcass weights were consistently obtained from hybrid stags grazing on chicory, with values for red deer and hybrid stags being 56.0 and 59.3 kg when grazed on chicory and 48.6 and 53.3 kg respectively when grazed on pasture. Chicory had a higher organic matter digestibility (OMO) and VFI than pasture during autumn but similar values in spring, accounting for its autumn growth stimulation. Carcass subcutaneous fat depth (GR) was higher for deer grazing chicory than pasture, but after being adjusted to equal carcass weight, there was no difference in GR measurement. Relative to deer grazing on pasture, grazing on chicory increased total spiker velvet antler production (323 v 225 g/stag), by advancing the dates of pedicle initiation (18 days), velvet antler initiation (24 days), and first velvet cutting (17 days) and increasing the rate of velvet antler length growth. Initiation of velvet growth was correlated with liveweight, with each 10 kg increase in liveweight advancing the dates of pedicle initiation, commencement of velvet growth and first velvet cutting by 10, 18 and 13 days respectively. Correction of the data to equal liveweight removed a component of the advancement produced from feeding on chicory, but an effect still remained due to chicory feeding per se. It was concluded that grazing chicory not only increased carcass weight (especially in hybrid stags), but also increased velvet antler production. This was achieved by increased VFI and increased OMO of chicory in autumn, relative to deer grazing pasture, and probably by increased absorption of protein and minerals in deer fed chicory. 3. OMO of lotus was higher than that of pasture during autumn, but not in spring. The OMO of either chicory or lotus showed little change between seasons, but pasture changed with the season, being of lowest OMO in autumn and highest OMO in spring. 4. Responses to deer grazing lotus were limited by the reduced number of grazing days that could be achieved, due to problems in lotus establishment. In spite of these problems, grazing lotus (48 gCT/kg OM) did increase the LWG of stags during autumn (248 v 176 g/day) and increased the efficiency of growth in spring, with LWG being similar to deer grazing pasture, but VFI being lower (1.53 v 2.00 kgOM/day) for lotus compared to pasture. Although deer grazing lotus had a similar carcass weight compared to deer grazing pasture, dressing-out percentages of deer grazing lotus were higher than that of deer grazing pasture (56.4 v 53.2 %). The carcass GR tissue depth of deer grazing lotus had similar values compared to pasture. There was no interaction between forage and genotype for carcass weight and dressing out percentage. Stags grazing lotus did not show any advancement in dates of pedicle initiation, velvet antler initiation and weight of velvet production compared to stags grazing pasture. 5. Total condensed tannin (CT) concentration in lotus was 48 and 13 g/kgOM in hand plucked and oesophageal fistulae (OF) extrusa samples respectively. Most CT in hand plucked lotus samples was extractable, with much smaller amounts being protein-bound or fibre-bound. Extractable CT was not detected in lotus OF extrusa samples, and the concentration of protein-bound and fibre-bound CT remained similar to hand plucked samples. Therefore, after chewing during eating, the extractable component of CT in lotus feed could not be extracted and detected by the Butanol/HCI analysis methods and may have been bound to deer salivary proteins. Total CT in both hand plucked and OF extrusa samples was 3.1 v 5.8 g/kgOM for chicory and 0.3 v 1.5 g/kgOM for pasture. As a result, chewing (in OF samples) did not reduce the CT content of pasture or chicory. This may be due to the low concentration of extractable CT (and high proportions of bound CT) in these forages, which may have limited access for the deer salivary CT-binding proteins. 6. Overall it was concluded that chicory was of very high feeding value (FV) and had excellent nutritional advantages for increasing deer production. However, crops of chicory need to have specialised grazing management to increase persistency. New chicory cultivars need to be selected to increase persistency and to reduce reproductive stem formation during summer. Effects of protein supply on initiation of pedicle and velvet antler development in weaner stags grazing fresh forages also needs to be studied. The small responses obtained in the present study give some indication that the CT content of Lotus comiculatus may have a number of values for improving the efficiency of growth in young deer. Further experiments are needed in this area.Item Utilising bioeconomic modelling to examine the impact of lambing percentages and pre-weaning lamb growth rates on farm profitability : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Agricultural Science, School of Agriculture and Environment, Massey University, Manawatu, New Zealand(Massey University, 2022) Moloney, Adam JamesSince 1980, the production and sale of sheep for meat has overtaken wool as the primary profit driver of Class 4 sheep enterprises in the Western North Island of New Zealand. While the sale of cull ewes and rams contributes to sheep enterprise production it’s the production of lamb that contributes the greatest amount. Lambs born on farm can either be grown to heavier liveweights and sent direct to the works (termed prime for slaughter) or sold as store lambs for others to finish. Therefore, the production of lamb as a profit driver is dependent on the number of lambs along with the individual liveweight of each lamb. There is, however, no recent information that directly quantifies and compares the impacts of either increased lamb numbers, increased lamb liveweights, or a combination of both which maximises farmer profit. Bio-economic modelling is a relatively recently adapted tool used in agricultural production systems such as New Zealand sheep enterprises. A bio-economic systems dynamics model has recently been created to compare changes in various sheep enterprises in New Zealand, with the model output production values found to be close to realised values. This bio-economic systems-dynamic model was identified as the most suitable model to use to complete this research. The specific objectives of this research were to update the current STELLA bio-economic system-dynamic model with more recent industry statistics before running eight scenarios with differing lambing percentage and pre-weaning growth rates to examine the impact on operating profitability. The model has six key major modules within the sheep enterprise: the purebred flock, feed supply, feed demand, feed balance, wool production, and economics. These major modules all had submodules. Model inputs were driven by recently published industry standards, ensuring model outputs would replicate realised values as closely as possible. Scenario 1 uses New Zealand average values for lambing percentage (133.5%) and lamb weaning weight. Scenarios 2, 3 and 4 use average lamb weaning weights but had lambing percentages of 140%, 150% and 160% respectively. Scenarios 5, 6 & 7 used average lambing percentage (133.5%) but has 10%, 20% & 30% greater pre-weaning lamb growth rates respectively. Scenario 8 had a lambing percentage of 140% and 10% increased pre-weaning lamb growth rates. Increasing lambing percentage from 133.5% in scenario 1 to 160% in scenario 4 increased the proportion of lambs sold store due to a greater proportion of lambs being born as multiples. This scenario increased farm cash operating surplus from ‡2 91/ha to ‡3 68/ha. Gestational energy demand limited flock size, with the number of ewes decreasing from scenario 1 to 4. Increasing pre-weaning lamb growth rates to 30% (scenario 7) above average (scenario 1) while leaving lambing percentage as average also decreased flock size but increased the farm COS from ‡2 91/ha to ‡4 44/ha. Lactational demand to meet the increased lamb growth was the factor limiting flock size. In the scenario with 140% lambing and a 10% increase in pre-weaning lamb growth rates (scenario 8) farm COS increased to ‡3 65/ha, ‡7 4/ha above scenario 1. Overall, increasing pre-weaning lamb growth was more profitable than increasing lambing percentage. Therefore the results of this research indicates that if a farmer has a lambing percentage of 140% or above, it is recommended emphasis should be placed on improving pre-weaning lamb growth rates compared to lambing percentage. There are several further considerations such as feed supply and lamb numbers, which must be considered before using these results. With the model relying solely on pasture for feed, any circumstances that leads to reduced feed supply may reduce the viability of these results.Item Modelling the role of dairy-origin cattle for young beef production in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Manawatu, New Zealand(Massey University, 2022) Addis, Addisu HailuApproximately 42% of calves produced annually in the New Zealand dairy industry are slaughtered by 2-weeks of age. This is seen as a wasted economic opportunity and has perceived welfare and ethical issues which could potentially affect both the dairy and beef trade. Young beef cattle production has been proposed to finish these calves for beef at 8 to 12-months of age. This study employed mathematical models to: 1) predict hind-leg muscle weight from young beef as an indirect indicator of saleable meat yield, 2) understand feed utilization and financial effects and 3) acceptance level of young beef cattle within the existing New Zealand beef cattle production systems. A univariate analysis using carcass weight explained 61% of variations in hind-leg muscle weight. This was improved by 6% in multivariate regression analysis using carcass weight, wither height and eye muscle area. Identifying additional traits in young beef cattle would improve the prediction accuracy and efficiency of the equations. A profit optimization model developed in this study identified selling strategies of beef cattle and sheep activities to increase farm profitability and pasture utilization on beef cattle and sheep farms. Including young beef cattle in the existing beef cattle and sheep farms increased the number of beef cattle processed per hectare, farm carcass output and pasture utilization. However, the farm earnings per hectare was lower than the optimized farm when carcasses from young beef cattle were processed under manufacturer beef price (i.e., NZ$ 4.50). Bulls (mainly Holstein-Friesian and Holstein-Frisian-Jersey cross breeds) accounted more than 50% of the total dairy-origin beef cattle processed in agent-based modelling (ABM). The uptake of Jersey breed for beef finishing was lower than 5% of the total dairy-origin beef cattle. Young beef cattle finishing under NZ$ 4.50 per kg carcass was not competitive with the traditional beef finishing systems. A 10% increase in value per kg carcass for young beef allowed them to contribute 6% of the total processed dairy-origin beef cattle. Incorporating consumers perspectives and other decision alternatives for the finisher could improve decision making on the use of young beef cattle in New Zealand.Item Growth and carcass characteristics of beef-cross-dairy-breed cattle : breed and sex effects : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science, Massey University, Palmerston North, New Zealand(Massey University, 2021) Williamson, Holly RuthApproximately two thirds of New Zealand’s annual cattle slaughter originates from the dairy industry in the form of cull cows, bobby calves and calves retained for beef finishing. Bobby calf slaughter for pet food and veal is a system of low production efficiency, making up 41.1% of the annual cattle slaughter on a per head basis, but comprising only 4.3% of the total annual carcass weight produced in New Zealand. These underutilised surplus calves provide an opportunity to increase beef production by finishing them at either the traditional slaughter age of around 24 months, or in a novel yearling system finishing cattle before 12 months. This study aimed to investigate different factors influencing the performance of beef-cross-dairy-breed cattle through two separate experiments. The objective of the first experiment (chapter 3) was to investigate the effect of dam breed from dams with varying proportions of Friesian and Jersey genetics on growth traits and carcass characteristics of their dairy-beef progeny slaughtered between 24 and 30 months of age. The primary objective of the second experiment (chapter 4) was to investigate the effect of sex on carcass and meat quality characteristics of 11- month-old Stabilizer-Friesian-Jersey heifers and steers. The first experiment involved 142 heifers and 203 steers born in the spring of 2018 to Friesian (F), Friesian-cross (FX), Friesian-Jersey (FJ) and Jersey-cross (JX) cows. Calves were artificially reared before drafting into four management herds and were slaughtered between October 2020 and March 2021. Calves from F dams took less time to reach a set weaning weight (100kg), and had greater live weights throughout the study than those from other dam breeds. Carcass weights were greater for progeny from F dams (286kg) than those from FX (297kg), FJ (275kg) and JX (276kg) dams. Yellow fat score was greatest for progeny of JX dams (3.33) than for progeny of F (3.01), FX (3.04) and FJ (3.05) dams. The frequency of yellowness scores of ≥ 5 (on a 1-9 scale) was also greatest for progeny of JX dams (17.1% compared to 2.6%, 5.6% and 9.2% for progeny of F, FX, and FJ dams, respectively). Therefore, calves from dams with a greater proportion of Jersey genetics will have lower live and carcass weights and yellower fat than those from dams with a greater proportion of Friesian genetics. The second experiment involved 24 Stabilizer-Friesian-Jersey cattle (12 heifers and 12 steers) born in the spring of 2018 and artificially reared before finishing as one herd until slaughter at 11 months of age. The Stabilizer is a four-breed composite comprising 25% each of the Angus, Hereford, Simmental and Gelbvieh breeds. Carcass weight and dressing out was greater for steers (157kg and 48.6%) than heifers (148kg and 47.1%). Heifers had a greater muscle to bone ratio (7.76) than steers (7.09). Cooking loss was greater in heifers (37.8%) than in steers (35.6%) but all other meat quality characteristics were similar between the sexes. Therefore, meat from yearling beef-cross-dairy-breed heifers and steers could be classed as one product. Aging decreased shear force of meat (4.65kg for aged compared to 5.51kg for unaged). Unaged beef was still highly tender, suggesting that aging was unnecessary to provide tender beef.